Increased production of acetyl-coenzyme a and derived products in yeasts

Abstract

The present disclosure provides a recombinant yeast host cell having a plurality of native and / or heterologous enzymes that function in an engineered metabolic pathway to convert fructose-6-phosphate to acetyl-coenzyme A. The recombinant yeast host cell can be used, for example, in a process for making acetyl-coenzyme A, acetone and / or isopropanol. The plurality of native and / or heterologous enzymes is activated, upregulated, or overexpressed. The plurality of native and / or heterologous enzymes comprises a phosphoketolase; and optionally an acetate kinase; and / or a phosphotransacetylase. The recombinant yeast host cell comprises at least one of: at least two copies of a heterologous nucleic acid molecule encoding the phosphoketolase; a native and / or heterologous enzyme that functions in an engineered non-oxidative pentose phosphate pathway, wherein the native and / or heterologous enzyme is activated, upregulated, or overexpressed; and / or a native and / or heterologous protein that functions in an engineered metabolic pathway to convert pantothenate into acetyl-coenzyme A, wherein the native and / or heterologous protein is activated, upregulated or overexpressed and comprises at least one of: FEN2 or CAB1.

Description

INCREASED PRODUCTION OF ACETYL-COENZYME A AND DERIVED PRODUCTS IN YEASTSTECHNOLOGICAL FIELD

[0001] The present disclosure concerns a recombinant yeast host cell for producing acetyl-coenzyme A as well as products derived therefrom.BACKGROUND

[0002] Production of non-ethanol chemicals during fermentation of biomass (e.g., corn, sugarcane, or lignocellulosic) derived sugars has been pursued for many years to achieve several goals, including 1 ) establishing their sourcing from renewable as opposed to fossil resources, 2) reducing the carbon intensity of these chemicals, 3) reducing the cost of production of these chemicals, and 4) increasing the diversification and economic performance of fuel and chemical ethanol fermentation facilities. Several companies are working to commercialize the fermentative production of non-ethanol chemicals. Yet, large scale production of non-ethanol chemicals from biomass remains rare.

[0003] One promising set of chemicals to produce during fermentation is acetone and isopropanol (2-propanol). These chemicals are used in very large quantities in a variety of applications as solvents and as precursors to produce polypropylene. The scale of the markets for these chemicals makes them compatible for production with the infrastructure currently used to produce fuel ethanol from corn and sugarcane. Being able to produce these compounds using this infrastructure would meet the four goals discussed above.

[0004] It would be desirable to be provided with a yeast capable of producing increased levels of acetone and / or isopropanol as well as process using same to produce acetone and / or isopropanol.SUMMARY

[0005] The present disclosure concerns a recombinant yeast host cell capable of producing a higher amount of acetyl-coenzyme A and consequently a higher amount of derived products (such as, for example acetone and / or isopropanol). Furthermore, the present disclosure concerns a recombinant yeast host cell capable of producing higher amount of acetyl-coenzyme A which produces acetone and / or isopropanol in combination with ethanol. The present disclosure also concerns processes for makinga higher amount of acetyl-coenzyme A, a higher amount of acetone and / or a higher amount of isopropanol in the presence of a biomass.

[0006] According to a first aspect, the present disclosure provides a recombinant yeast host cell having one or more of native and / or heterologous enzymes that function in an engineered metabolic pathway to convert fructose-6-phosphate to acetyl-coenzyme A, wherein the plurality of native and / or heterologous enzymes is activated, upregulated, or overexpressed. The recombinant yeast host cell comprises a phosphoketolase; and optionally an acetate kinase, and / or a phosphotransacetylase. In such embodiment, the recombinant yeast host cell comprises at least one of: (i) at least two copies of a heterologous nucleic acid molecule encoding the phosphoketolase; (ii) a native and / or heterologous enzyme that functions in an engineered non-oxidative pentose phosphate pathway, wherein the native and / or heterologous enzyme is activated, upregulated, or overexpressed; and / or (iii) a native and / or heterologous protein that functions in an engineered metabolic pathway to convert pantothenate into acetyl-coenzyme A, wherein the native and / or heterologous protein is activated, upregulated or overexpressed and comprises at least one of: FEN2 or CAB1. In an embodiment, the recombinant yeast host cell further comprises one or more of native and / or heterologous enzymes that function in an engineered metabolic pathway to convert acetate into acetyl-coenzyme A, wherein the plurality of the native and / or heterologous enzymes comprises an activated, upregulated or overexpressed ACS2; and optionally a deleted native ALD6. In another embodiment, the recombinant yeast host cell further comprises a native and / or heterologous enzyme that functions in an engineered metabolic pathway to convert acetyl-coenzyme A and acetate to acetone, wherein the native and / or heterologous enzyme is activated, upregulated, or overexpressed and comprises at least one of: a thiolase, a coenzyme A transferase, or an acetoacetate decarboxylase. In yet another embodiment, the recombinant yeast host cell further comprises a native enzyme that functions in a pathway to convert acetone to isopropanol, wherein the native enzyme comprises an alcohol dehydrogenase. In some embodiments, the alcohol dehydrogenase is a secondary alcohol dehydrogenase. In yet additional embodiments, the phosphoketolase: has the ability to convert D-xylulose 5-phosphate into D- glyceraldehyde 3-phosphate and acetyl-phosphate; has the ability to convert D- fructose 6-phosphate into D-erythrose 4-phosphate; has the ability to convert D- sedoheptulose 7-phosphate into D-ribose 5-phosphate; has single- or multiple-specificity; is of prokaryotic or eukaryotic origin; is encoded by a phk1 gene or a phk2 gene; is derived from Bifidobacterium, Lactobacillus, Leuconostoc, Penicillium, Aspergillus, Oenococcus or Neurospora species; is derived from Bifidobacterium bifidum, Bifidobacterium brevi, Bifidobacterium gallicum, Bifidobacterium animalis, Bifidobacterium adolescentis, Lactobacillus pentosum, Lactobacillus acidophilus, Lactobacillus casei, Lactiplantibacillus plantarum, Penicillium chrysogenum, Aspergillus niger, Aspergillus nidulans, Aspergillus clavatus, Neurospora crassa, Leuconostoc mesenteroides or Oenococcus oeni; has the amino acid sequence of SEQ ID NO: 4, 37, 39, 41 , 43, 45, 47, 49, 51 , 53, 55, 57, 59, 61 , 63 or 65; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 3, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62 or 64. In some additional embodiments, the recombinant yeast host cell comprises 4 copies or more of the heterologous nucleic acid molecule encoding the phosphoketolase. In yet additional embodiments, the native and / or heterologous enzyme that functions in the engineered non-oxidative pentose phosphate pathway comprises at least one of: a transaldolase, a transketolase, an epimerase, or an isomerase. In some embodiments, the transaldolase: has the ability to convert glyceraldehyde 3-phosphate into erythrose 4- phosphate; has the ability to convert sedoheptulose 7-phosphate into fructose 6- phosphate; is heterologous; is of prokaryotic or eukaryotic origin; is a TAL1 polypeptide; is encoded by a tall gene; is derived from Saccharomyces sp.; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 14; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 13. In some embodiments, the transketolase: has the ability to convert ribose 5-phosphate into glyceraldehyde 3-phosphate; has the ability to convert fructose 6- phosphate into xylulose 5-phosphate; has the ability to convert xylulose 5-phoshate into sedoheptulose 7-phosphate; has the ability to convert glyceraldehyde 3-phosphate into erythrose 4-phosphate; is heterologous; is of prokaryotic or eukaryotic origin; is a TKL1 polypeptide; is encoded by a tkl1 gene; is derived from Saccharomyces sp.; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 12; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 11. In some embodiments, the epimerase: has the ability to convert ribulose 5-phosphate into xylulose 5-phosphate; has the ability to convert xylulose 5- phosphate into ribulose 5-phosphate; is heterologous; is of prokaryotic or eukaryotic origin; is a RPE1 polypeptide; is encoded by a rpe1 gene; is derived fromSaccharomyces sp.; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 16; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 15. In some embodiments, the isomerase: has the ability to convert ribulose 5-phosphate into ribose 5-phosphate; has the ability to convert ribose 5-phosphate into ribulose 5-phosphate; is heterologous; is of prokaryotic or eukaryotic origin; is a RKI1 polypeptide; is encoded by a rki1 gene; is derived from Saccharomyces sp.; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 18; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 17. In further embodiments, the native and / or heterologous enzyme that functions in the engineered non-oxidative pentose phosphate pathway comprises at least two of the transaldolase, the transketolase, the epimerase, or the isomerase. In additional embodiments, the native and / or heterologous enzyme that functions in an engineered non-oxidative pentose phosphate pathway comprises at least three of the transaldolase, the transketolase, the epimerase, or the isomerase. In yet further embodiments, the native and / or heterologous enzyme that functions in an engineered non-oxidative pentose phosphate pathway comprises the transaldolase, the transketolase, the epimerase, and the isomerase. In some embodiments, the FEN2: is a plasma membrane proton- pantothenate symporter; is heterologous; is of prokaryotic or eukaryotic origin is encoded by a fen2 gene; is derived from Saccharomyces sp.; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 26; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 25. In some embodiments, the CAB1 : has pantothenate kinase activity; is heterologous; is of prokaryotic or eukaryotic origin; is encoded by a cab1 gene; is derived from Saccharomyces sp.; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 28; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 27. In some specific embodiments, CAB1 is CAB1W331 R. In yet additional embodiments, the native and / or heterologous protein that functions in the engineered metabolic pathway to convert pantothenate into acetyl-coenzyme A comprises FEN2. In yet further embodiments, the native and / or heterologous protein that functions in the engineered metabolic pathway to convert pantothenate into acetyl-coenzyme A comprises CAB1 . In still additional embodiments, the native and / or heterologous protein that functions in the engineered metabolic pathway to convert pantothenate into acetyl-coenzyme A comprises FEN2 and CAB1 .In some embodiments, the ACS2: has the ability to convert acetate into acetylcoenzyme A; is heterologous; is from prokaryotic or eukaryotic origin; is encoded by a acs2 gene; is derived from Saccharomyces sp.; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 2; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 1. In embodiments, the thiolase: is heterologous; is of prokaryotic or eukaryotic origin; is encoded by a thl gene, a erg10 gene or a phaA gene; is derived from derived from Saccharomyces sp.; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 10; and / or has the nucleic acid sequence of SEQ ID NO: 9. In embodiments, the coenzyme A transferase: is heterologous; is of prokaryotic or eukaryotic origin; is encoded by a ctfA gene and a ctfB gene; is encoded by a atoD and / or a atoA gene; is derived from Alkaliphilus sp.; is derived from Alkaliphilus metalliredigens', has the amino acid sequence of SEQ ID NO: 20 and / or 22; and / or has the nucleic acid sequence SEQ ID NO: 19 and / or 21. In embodiments, the acetoacetate decarboxylase is heterologous; is of prokaryotic or eukaryotic origin; is encoded by a adc gene; is derived from Paenibacillus sp.; is derived from Paenibacillus polymyxa', has the amino acid sequence of SEQ ID NO: 24; and / or has the nucleic acid sequence of SEQ ID NO: 23. In a further embodiment, the recombinant yeast host cell comprises at least two of: at least 2 copies of the heterologous nucleic acid molecule encoding the phosphoketolase, the native and / or heterologous enzyme that functions in the engineered non-oxidative pentose phosphate pathway, or the native and / or heterologous protein that functions in the engineered metabolic pathway to convert pantothenate into acetyl-coenzyme A. In still another embodiment, the recombinant yeast host cell comprises at least 2 copies of the heterologous nucleic acid molecule encoding the phosphoketolase, the native and / or heterologous enzyme that functions in the engineered non-oxidative pentose phosphate pathway, and the native and / or heterologous protein that functions in the engineered metabolic pathway to convert pantothenate into acetyl-coenzyme A In yet another embodiment, the recombinant yeast host cell is from the Saccharomyces genus. In still a further embodiment, the recombinant yeast host cell is from the Saccharomyces cerevisiae species. In yet another embodiment, the recombinant yeast host cell also produces ethanol.

[0007] In a second aspect, the present disclosure provides a process for increasing the acetyl-coenzyme A production in a recombinant yeast host cell. The process comprises contacting a biomass with the recombinant yeast host cell definedherein under conditions allowing the production of acetyl -coenzyme A. In such embodiment, the acetyl-coenzyme A production in the recombinant yeast host cell is increased when compared to a control yeast host cell lacking (i), (ii), and (iii) as defined above.

[0008] In a third aspect, the present disclosure provides a process for converting a biomass into acetone. The process comprises contacting a biomass with the recombinant yeast host cell defined herein under conditions allowing the conversion of at least part of the biomass into acetone.

[0009] In a fourth aspect, the present disclosure provides a process for converting a biomass into isopropanol. The process comprises contacting a biomass with the recombinant yeast host cell defined herein under conditions allowing the conversion of at least part of the biomass into isopropanol.DETAILED DESCRIPTION OF THE DRAWINGS

[0010] Having thus generally described the nature of the invention, reference will now be made to the accompanying drawings, showing by way of illustration, a preferred embodiment thereof, and in which:

[0011] Figure 1 provides a scheme of metabolic pathways of interest which are native and heterologous to Saccharomyces cerevisiae to increase the production of acetyl-coenzyme A and derived products such as acetone and / or isopropanol.

[0012] Figure 2 provides the metabolites profiles obtained after fermentation by strains M2390, M28452, M28256, M28258 as well as isolates T11214, T11212 and T11213. Results are shown as g / L of acetone and acetate in function of the strain / isolate tested.

[0013] Figure 3 provides a schematic of the metabolic pathway for making coenzyme A.

[0014] Figure 4 provides the metabolites profiles obtained after fermentation by strains M2390, M28452, M28707, M28256, M28701 , M28258, and M28703. Results are shown as g / L of acetone and acetic acid in function of the strain tested.

[0015] Figure 5 provides the metabolites profiles obtained after fermentation by strains M2390, and M29069 as well as isolates T12127, T12129, and T12128. Results are shown as g / L of acetone and acetic acid in function of the strain / isolate tested.

[0016] Figure 6 provides the metabolites profiles obtained after fermentation by isolates T12104, T12105, and T12106. Results are shown as g / L of acetone and acetic acid in function of the strain tested.

[0017] Figure 7 provides the metabolites profiles obtained after fermentation by strains M2390, M29069, and M30292 as well as isolates T12200-8, T12203-7 and T12199-7. Results are shown as g / L of isopropanol (IPA), acetone, and acetic acid in function of the strain / isolate tested.

[0018] Figure 8 provides a description of the biological sequences of the present disclosure.DETAILED DESCRIPTION

[0019] The present disclosure concerns a recombinant yeast host cell capable of producing a higher amount of acetyl-coenzyme A (acetyl-coA) and consequently a higher amount of derived products (such as, for example acetone and / or isopropanol). Amongst other things, the recombinant yeast host cell comprises at least one of (i) at least two copies of a heterologous nucleic acid molecule encoding the phosphoketolase, (ii) a native and / or heterologous enzyme that functions in an engineered non-oxidative pentose phosphate pathway, wherein the native and / or heterologous enzyme is activated, upregulated, or overexpressed, and / or (iii) a native and / or heterologous protein that functions in an engineered metabolic pathway to convert pantothenate into acetyl-coenzyme A, wherein the native and / or heterologous protein is activated, upregulated or overexpressed and comprises at least one of: FEN2 or CAB1. The amount of acetyl-coenzyme A (and associated derived product) observed when culturing the recombinant yeast host cell is higher than a control yeast host cell lacking at least one of (i), (ii) and / or (iii).Recombinant yeast host cell

[0020] The present disclosure provides a recombinant yeast host cell. These recombinant yeast host cells can be obtained by introducing one or more genetic modifications in a corresponding native (parental) yeast host cell. When the genetic modification is aimed at reducing or inhibiting the expression of a specific targeted gene (which is endogenous to the host cell), the genetic modifications can be made in one or all copies of the targeted gene(s). When the genetic modification is aimed at increasing the expression of a specific targeted gene, the genetic modification can be made in one or multiple genetic locations. In the context of the present disclosure,when a yeast host cell is qualified as being “genetically engineered”, it is understood to mean that it has been manipulated to either add at least one or more heterologous or exogenous nucleic acid residue and / or removed at least one endogenous (or native) nucleic acid residue. In some embodiments, the one or more nucleic acid residues that are added can be derived from a heterologous cell or the recombinant host cell itself. In the latter scenario, the nucleic acid residue(s) is (are) added at a genomic location which is different than the native genomic location. The genetic manipulations did not occur in nature and are the results of in vitro manipulations of the native yeast or bacterial host cell.

[0021] When expressed in recombinant yeast host cells, the polypeptides (including the enzymes) described herein are encoded on one or more heterologous nucleic acid molecule. The term “heterologous” when used in reference to a nucleic acid molecule (such as a promoter or a coding sequence) refers to a nucleic acid molecule that is not natively found in the recombinant host cell. “Heterologous” also includes a native coding region, or portion thereof, that is removed from the source organism and subsequently reintroduced into the source organism in a form that is different from the corresponding native gene, e.g., not in its natural location in the organism's genome or as additional copies at its natural location. The heterologous nucleic acid molecule is purposively introduced into the recombinant yeast host cell. In some embodiments, the term “heterologous” as used herein also refers to an element (nucleic acid or protein) that is derived from a source other than the endogenous source. Thus, for example, a heterologous element could be derived from a different strain of host cell, or from an organism of a different taxonomic group (e.g., different kingdom, phylum, class, order, family genus, or species, or any subgroup within one of these classifications).

[0022] When a heterologous nucleic acid molecule is present in the recombinant yeast host cell, it can be integrated in the host cell’s genome. The term “integrated” as used herein refers to genetic elements that are placed, through molecular biology techniques, into the chromosome of a yeast host cell. For example, genetic elements can be placed into the chromosome(s) of the host cell as opposed to in a vector such as a plasmid carried by the host cell. Methods for integrating genetic elements into the genome of a host cell are well known in the art and include homologous recombination. The heterologous nucleic acid molecule can be present in one or more copies in the yeast host cell’s chromosome. Alternatively, the heterologous nucleic acid moleculecan be independently replicating from the yeast host cell’s chromosome. In such embodiment, the nucleic acid molecule can be stable and self-replicating.

[0023] In some embodiments, heterologous nucleic acid molecules which can be introduced into the recombinant yeast host cells are codon-optimized with respect to the intended recipient recombinant yeast host cell. As used herein the term “codon- optimized coding region” means a nucleic acid coding region that has been adapted for expression in the cells of a given organism by replacing at least one, or more than one, codons with one or more codons that are more frequently used in the genes of that organism. In general, highly expressed genes in an organism are biased towards codons that are recognized by the most abundant tRNA species in that organism. One measure of this bias is the “codon adaptation index” or “CAI,” which measures the extent to which the codons used to encode each amino acid in a particular gene are those which occur most frequently in a reference set of highly expressed genes from an organism. The CAI of codon optimized heterologous nucleic acid molecule described herein corresponds to between about 0.8 and 1.0, between about 0.8 and 0.9, or about 1.0. In some embodiments, heterologous nucleic acid molecules which can be introduced into the recombinant host cells are codon-optimized with respect to the intended recipient recombinant host cell so as to limit or prevent homologous recombination with the corresponding native gene.

[0024] The heterologous nucleic acid molecules of the present disclosure can comprise a coding region for the one or more polypeptides (such as enzymes) to be expressed by the host cell. A DNA or RNA “coding region” is a DNA or RNA molecule which is transcribed and / or translated into a polypeptide in a cell in vitro or in vivo when placed under the control of appropriate regulatory sequences. “Suitable regulatory regions" refer to nucleic acid regions located upstream (5' non-coding sequences), within, or downstream (3' non-coding sequences) of a coding region, and which influence the transcription, RNA processing or stability, or translation of the associated coding region. Regulatory regions may include promoters, translation leader sequences, RNA processing sites, effector binding sites and stem-loop structures. The boundaries of the coding region are determined by a start codon at the 5' (amino) terminus and a translation stop codon at the 3' (carboxyl) terminus. A coding region can include, but is not limited to, prokaryotic regions, cDNA from mRNA, genomic DNA molecules, synthetic DNA molecules, or RNA molecules. If the coding region is intended for expression in a eukaryotic cell, a polyadenylation signal and transcriptionio termination sequence will usually be located 3' to the coding region. In an embodiment, the coding region can be referred to as an open reading frame. “Open reading frame" is abbreviated ORF and means a length of nucleic acid, either DNA, cDNA or RNA, that comprises a translation start signal or initiation codon, such as an ATG or AUG, and a termination codon and can be potentially translated into a polypeptide sequence.

[0025] The nucleic acid molecules described herein can comprise a non-coding region, for example a transcriptional and / or translational control regions. “Transcriptional and translational control regions” are DNA regulatory regions, such as promoters, enhancers, terminators, and the like, that provide for the expression of a coding region in a host cell. In eukaryotic cells, polyadenylation signals are control regions.

[0026] The heterologous nucleic acid molecule can be introduced in the host cell using a vector. A “vector,” e g., a “plasmid”, “cosmid” or “artificial chromosome” (such as, for example, a yeast artificial chromosome) refers to an extra chromosomal element and is usually in the form of a circular double-stranded DNA molecule. Such vectors may be autonomously replicating sequences, genome integrating sequences, phage or nucleotide sequences, linear, circular, or supercoiled, of a single- or doublestranded DNA or RNA, derived from any source, in which a number of nucleotide sequences have been joined or recombined into a unique construction which is capable of introducing a promoter fragment and DNA sequence for a selected gene product along with appropriate 3' untranslated sequence into a host cell.

[0027] In the heterologous nucleic acid molecules described herein, the promoter and the nucleic acid molecule coding for the one or more polypeptides (such as the one or more enzymes) can be operatively linked to one another. In the context of the present disclosure, the expressions “operatively linked” or “operatively associated” refers to fact that the promoter is physically associated to the nucleotide acid molecule coding for the one or more enzyme in a manner that allows, under certain conditions, for expression of the one or more polypeptides from the heterologous nucleic acid molecule. In an embodiment, the promoter can be located upstream (5’) of the nucleic acid sequence coding for the one or more polypeptide. In still another embodiment, the promoter can be located downstream (3’) of the nucleic acid sequence coding for the one or more polypeptide. In the context of the present disclosure, one or more than one promoter can be included in the heterologous nucleic acid molecule. When more than one promoters are included in the heterologousnucleic acid molecule, each of the promoters is operatively linked to the nucleic acid sequence coding for the one or more polypeptide. The promoters can be located, in view of the nucleic acid molecule coding for the one or more protein, upstream, downstream as well as both upstream and downstream.

[0028] “Promoter” refers to a DNA fragment capable of controlling the expression of a coding sequence or functional RNA. The term “expression,” as used herein, refers to the transcription and stable accumulation of sense (mRNA) from the heterologous nucleic acid molecule described herein. Expression may also refer to translation of mRNA into a polypeptide. Promoters may be derived in their entirety from a native gene, or be composed of different elements derived from different promoters found in nature, or even comprise synthetic DNA segments. It is understood by those skilled in the art that different promoters may direct the expression at different stages of development, or in response to different environmental or physiological conditions. Promoters which cause a gene to be expressed in most cells at most times at a substantial similar level are commonly referred to as “constitutive promoters”. It is further recognized that since in most cases the exact boundaries of regulatory sequences have not been completely defined, DNA fragments of different lengths may have identical promoter activity. A promoter is generally bounded at its 3' terminus by the transcription initiation site and extends upstream (5' direction) to include the minimum number of bases or elements necessary to initiate transcription at levels detectable above background. Within the promoter will be found a transcription initiation site (conveniently defined for example, by mapping with nuclease S1 ), as well as protein binding domains (consensus sequences) responsible for the binding of the polymerase.

[0029] The promoter can be heterologous to the nucleic acid molecule encoding the one or more polypeptides. The promoter can be heterologous or derived from a strain being from the same genus or species as the yeast host cell. In an embodiment, the promoter is derived from the same genus or species of the yeast host cell and the heterologous polypeptide is derived from different genus than the yeast host cell.

[0030] In some embodiments, the present disclosure concerns the expression of a heterologous polypeptide (such as a heterologous enzyme), a variant thereof or a fragment thereof in a host cell. A variant comprises at least one amino acid difference when compared to the amino acid sequence of the wild-type polypeptide. The polypeptide “variants” have at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%,95%, 96%, 97%, 98% or 99% identity to the heterologous polypeptides described herein. The term “percent identity”, as known in the art, is a relationship between two or more polypeptide sequences or two or more polynucleotide sequences, as determined by comparing the sequences. The level of identity can be determined conventionally using known computer programs. Identity can be readily calculated by known methods, including but not limited to those described in: Computational Molecular Biology (Lesk, A. M., ed.) Oxford University Press, NY (1988); Biocomputing: Informatics and Genome Projects (Smith, D. W., ed.) Academic Press, NY (1993); Computer Analysis of Sequence Data, Part I (Griffin, A. M., and Griffin, H. G., eds.) Humana Press, NJ (1994); Sequence Analysis in Molecular Biology (von Heinje, G., ed.) Academic Press (1987); and Sequence Analysis Primer (Gribskov, M. and Devereux, J., eds.) Stockton Press, NY (1991 ). Preferred methods to determine identity are designed to give the best match between the sequences tested. Methods to determine identity and similarity are codified in publicly available computer programs. Sequence alignments and percent identity calculations may be performed using the Megalign program of the LASERGENE bioinformatics computing suite (DNASTAR Inc., Madison, Wis.). Multiple alignments of the sequences disclosed herein were performed using the Clustal method of alignment (Higgins and Sharp (1989) CABIOS. 5:151 -153) with the default parameters (GAP PENALTY=10, GAP LENGTH PEN ALT Y= 10). Default parameters for pairwise alignments using the Clustal method were KTUPLB 1 , GAP PENALTY=3, WIND0W=5 and DIAGONALS SAVED=5.

[0031] The heterologous polypeptide variants exhibit the biological activity associated with the wild-type heterologous polypeptide. In an embodiment, the variant polypeptide exhibits at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% of the biological activity (which can be, in some embodiments, the enzymatic activity) of the wild-type heterologous polypeptide. The biological activity of the polypeptides can be determined by methods and assays known in the art.

[0032] The variant heterologous polypeptides described herein may be (i) one in which one or more of the amino acid residues are substituted with a conserved or non-conserved amino acid residue (preferably a conserved amino acid residue) and such substituted amino acid residue may or may not be one encoded by the genetic code, or (ii) one in which one or more of the amino acid residues includes a substituent group, or (iii) one in which the mature polypeptide is fused with another compound,such as a compound to increase the half-life of the polypeptide (for example, polyethylene glycol), or (iv) one in which the additional amino acids are fused to the mature polypeptide for purification of the polypeptide.

[0033] A “variant” of the polypeptide can be a conservative variant or an allelic variant. As used herein, a conservative variant refers to alterations in the amino acid sequence that do not adversely affect the biological functions of the enzyme. A substitution, insertion or deletion is said to adversely affect the protein when the altered sequence prevents or disrupts a biological function associated with the enzyme. For example, the overall charge, structure, or hydrophobic-hydrophilic properties of the polypeptide can be altered without adversely affecting a biological activity. Accordingly, the amino acid sequence can be altered, for example to render the polypeptide more hydrophobic or hydrophilic, without adversely affecting the biological activity of the polypeptide.

[0034] The heterologous polypeptide can be a fragment of a heterologous wildtype polypeptide or fragment of a variant polypeptide. Polypeptide “fragments” have at least at least 50, 100, 200, 300, 400, 500 or more consecutive amino acids of the polypeptide or the enzyme variant. A fragment comprises at least one less amino acid residue when compared to the amino acid sequence of the wild-type heterologous polypeptide or of the variant polypeptide. In some embodiments, the fragments corresponding to the wild-type polypeptide or variant polypeptide to which the signal sequence was removed. In some embodiments, the “fragments” have at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% identity to the wild-type polypeptides described herein. In some embodiments, fragments of the polypeptides can be employed for producing the corresponding full-length enzyme by peptide synthesis. Therefore, the fragments can be employed as intermediates for producing the full-length polypeptide.

[0035] The fragments of heterologous wild-type polypeptides or of variant polypeptides exhibit the biological activity of the heterologous wild-type polypeptide or of the variant polypeptide. In an embodiment, the fragment polypeptide exhibits at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% of the biological activity of the heterologous wild-type polypeptide or of the variant polypeptide. The biological activity of fragment polypeptides can be determined by methods and assays known in the art.

[0036] In some additional embodiments, the present disclosure also provides reducing the expression of or inactivating a gene ortholog of a gene known to encode a native enzyme. A “gene ortholog” is understood to be a gene in a different species that evolved from a common ancestral gene by speciation. In the context of the present invention, a gene ortholog encodes a polypeptide exhibiting the same biological function than the wild-type polypeptide.

[0037] In some further embodiments, the present disclosure also provides reducing the expression or inactivating a gene paralog of a gene known to encode an enzyme. A “gene paralog” is understood to be a gene related by duplication within the genome. In the context of the present invention, a gene paralog encodes a polypeptide that could exhibit the same biological function than the wild-type polypeptide.

[0038] The recombinant yeast host cell of the present disclosure has the ability to convert a biomass into one or more fermentation products (e.g., ethanol, in combination with acetone and isopropanol). In the context of the present disclosure, the recombinant yeast host cell is a fermenting yeast cell because it is capable of converting the biomass into the one or more fermentation products. Suitable fermenting yeasts and recombinant yeast host cells can be, for example, from the genus Saccharomyces, Kluyveromyces, Arxula, Debaryomyces, Candida, Pichia, Phaffia, Schizosaccharomyces, Hansenula, Kloeckera, Schwanniomyces, Komagataella or Yarrowia. Suitable yeast species can include, for example, S. cerevisiae, S. bulderi, S. barnetti, S. exiguus, S. uvarum, S. diastaticus, K. lactis, K. marxianus, K. phaffii, or K. fragilis. In some embodiments, the yeast is selected from the group consisting of Saccharomyces cerevisiae, Schizzosaccharomyces pombe, Candida albicans, Pichia pastoris, Pichia stipitis, Yarrowia lipolytica, Hansenula polymorpha, Phaffia rhodozyma, Candida utilis, Arxula adeninivorans, Debaryomyces hansenii, Debaryomyces polymorphus, Schizosaccharomyces pombe and Schwanniomyces occidentalis. In some embodiments, the host cell can be an oleaginous yeast cell. For example, the oleaginous yeast host cell can be from the genus Blakeslea, Candida, Cryptococcus, Cunninghamella, Lipomyces, Mortierella, Mucor, Phycomyces, Pythium, Rhodosporidum, Rhodotorula, Trichosporon or Yarrowia. In some alternative embodiments, the host cell can be an oleaginous microalgae host cell (e.g., for example, from the genus Thraustochytrium or Schizochytrium). In an embodiment, the fermenting yeast or recombinant yeast hostcell is from the genus Saccharomyces and, in some embodiments, from the species Saccharomyces cerevisiae.

[0039] The recombinant yeast host cell of the present disclosure has native and / or heterologous enzymes that function in an engineered metabolic pathway to convert fructose-6-phosphate to acetyl-coenzyme A. The engineered metabolic pathway to convert fructose-6-phosphate to acetyl-coenzyme A comprises a phosphoketolase, optionally in combination with an acetate kinase and / or a phosphotransacetylase. As such, the recombinant yeast host cell of the present disclosure comprises a phosphoketolase, alone or in combination with an acetate kinase, and / or a phosphotransacetylase. In some embodiments, the recombinant yeast host cell of the present disclosure comprises a phosphoketolase only. In additional embodiments, the recombinant yeast host cell of the present disclosure comprises a phosphoketolase and an acetate kinase. In further embodiments, the recombinant yeast host cell of the present disclosure comprises a phosphoketolase and a phosphotransacetylase. In yet other embodiments, the recombinant yeast host cell of the present disclosure comprises a phosphoketolase, an acetate kinase, and a phosphotransacetylase.

[0040] As used herein, the terms "phosphoketolase" and "PHK" are intended to include the enzymes capable of converting D-xylulose 5-phosphate to D- glyceraldehyde 3-phosphate and acetyl phosphate. The phosphoketolase can have a single-specificity activity (e.g., single-specificity phosphoketolase), and be only capable of converting D-xylulose 5-phosphate to D-glyceraldehyde 3-phosphate and acetyl phosphate. The phosphoketolase can have a multiple-specificity / dual-specificity (e.g., multiple-specificity or dual-specificity phosphoketolase), and be also capable of converting D-fructose 6-phosphate to D-erythrose 4-phosphate and / or D- sedoheptulose 7-phosphate into D-ribose 5-phosphate. Phosphoketolases include those enzymes that correspond to Enzyme Commission Number 4.1 .2.9 and 4.1 .2.22. The PHK is heterologous to the recombinant yeast host cell, and the recombinant yeast host cell of the present disclosure can comprise, in some embodiments, at least two copies of a heterologous nucleic acid encoding the PHK. In some embodiments, the PHK is of prokaryotic or eukaryotic origin. In other embodiments, the PHK can be encoded by a phk1 gene (e.g., PHK1 ) or a phk2 gene (e.g., PHK2). In some embodiments, the PHK is derived from Bifidobacterium sp., and in furtherembodiments from Bifidobacterium adolescentis. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 4, be a variant of the amino acid sequence of SEQ ID NO: 4 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 4 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 3 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 4 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived from Bifidobacterium sp., and in further embodiments from Bifidobacterium bifidum. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 43, be a variant of the amino acid sequence of SEQ ID NO: 43 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 43 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 42 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 43 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived from Bifidobacterium sp., and in further embodiments from Bifidobacterium gallicum. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 45, be a variant of the amino acid sequence of SEQ ID NO: 45 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 45 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 44 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 45 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived from Bifidobacterium sp., and in further embodiments from Bifidobacterium animalis. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 47, be a variant of the amino acid sequence of SEQ ID NO: 47 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 47 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, theheterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 46 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 47 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived from Bifidobacterium sp., and in further embodiments from Bifidobacterium breve. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 106, be a variant of the amino acid sequence of SEQ ID NO: 106 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 106 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 105 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 106 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived from Lactiplantibacillus sp. (previously referred to as Lactobacillus sp.), and in further embodiments from Lactiplantibacillus pentosum. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 49, be a variant of the amino acid sequence of SEQ ID NO: 49 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 49 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 48 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 49 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived from Lactiplantibacillus acidophilus. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 51 , be a variant of the amino acid sequence of SEQ ID NO: 51 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 51 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 50 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 51 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived from Lactiplantibacillus casei. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 41 , be a variant of the amino acid sequence of SEQ ID NO: 41 having PHK activity or be afragment of the amino acid sequence of SEQ ID NO: 41 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 40 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 41 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived Lactiplantibacillus plantarum. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 63 or 65, be a variant of the amino acid sequence of SEQ ID NO: 63 or 65 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 63 or 65 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 62 or 64 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 63 or 65 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived from Aspergillus sp., and in further embodiments from Aspergillus niger. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 37, be a variant of the amino acid sequence of SEQ ID NO: 37 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 37 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 36 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 37 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived from Aspergillus nidulans. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 55, be a variant of the amino acid sequence of SEQ ID NO: 55 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 55 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 54 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 55 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived from Aspergillus clavatus. In suchembodiments, the PHK can have the amino acid sequence of SEQ ID NO: 57, be a variant of the amino acid sequence of SEQ ID NO: 57 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 57 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 56 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 57 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived from Penicillium sp., and in further embodiments from Penicillium chrysogenum. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 53, be a variant of the amino acid sequence of SEQ ID NO: 53 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 53 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 52 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 53 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived from Neurospora sp., and in further embodiments from Neurospora crassa. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 39, be a variant of the amino acid sequence of SEQ ID NO: 39 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 39 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 38 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 39 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived from Leuconostoc sp., and in further embodiments from Leuconostoc mesenteroides. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 59, be a variant of the amino acid sequence of SEQ ID NO: 59 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 59 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acidsequence of SEQ ID NO: 58 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 59 (a variant thereof or a fragment thereof). In some embodiments, the PHK is derived from Oenococcus sp., and in further embodiments from Oenococcus oeni. In such embodiments, the PHK can have the amino acid sequence of SEQ ID NO: 61 , be a variant of the amino acid sequence of SEQ ID NO: 61 having PHK activity or be a fragment of the amino acid sequence of SEQ ID NO: 61 having PHK activity. The recombinant yeast host cell includes a copy (and in some embodiments at least two copies of) a heterologous nucleic acid molecule encoding the PHK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 60 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 61 (a variant thereof or a fragment thereof).

[0041] As indicated above, the recombinant yeast host cell of the present disclosure can comprise at least two copies of the heterologous nucleic acid molecule encoding the PHK per haploid genome. In some embodiments, the recombinant yeast host cell comprises two copies of the heterologous nucleic acid molecule encoding the PHK per haploid genome. In some additional embodiments, the recombinant yeast host cell of the present disclosure comprises at least three copies of the heterologous nucleic acid molecule encoding the PHK per haploid genome. In some embodiments, the recombinant yeast host cell comprises three copies of the heterologous nucleic acid molecule encoding the PHK per haploid genome. In some additional embodiments, the recombinant yeast host cell of the present disclosure comprises at least four copies of the heterologous nucleic acid molecule encoding the PHK per haploid genome. In some embodiments, the recombinant yeast host cell comprises four copies of the heterologous nucleic acid molecule encoding the PHK per haploid genome. In some additional embodiments, the recombinant yeast host cell of the present disclosure comprises at least five copies of the heterologous nucleic acid molecule encoding the PHK per haploid genome. In some embodiments, the recombinant yeast host cell comprises five copies of the heterologous nucleic acid molecule encoding the PHK per haploid genome. In some additional embodiments, the recombinant yeast host cell of the present disclosure comprises at least six copies of the heterologous nucleic acid molecule encoding the PHK per haploid genome. In some embodiments, the recombinant yeast host cell comprises six copies of the heterologous nucleic acid molecule encoding the PHK per haploid genome. In someadditional embodiments, the recombinant yeast host cell of the present disclosure comprises at least seven copies of the heterologous nucleic acid molecule encoding the PHK per haploid genome. In some embodiments, the recombinant yeast host cell comprises seven copies of the heterologous nucleic acid molecule encoding the PHK per haploid genome. In some additional embodiments, the recombinant yeast host cell of the present disclosure comprises at least eight copies of the heterologous nucleic acid molecule encoding the PHK per haploid genome. In some embodiments, the recombinant yeast host cell comprises eight copies of the heterologous nucleic acid molecule encoding the PHK per haploid genome.

[0042] The engineered metabolic pathway to convert fructose-6-phosphate to acetyl-coenzyme A can include, in some embodiments, an acetate kinase. As such, the recombinant yeast host cell of the present disclosure can include, in such embodiments, an acetate kinase. As used herein, the terms "acetate kinase" and "ACK" are intended to include the enzymes capable of converting acetate into acetylphosphate (acetyl-P). Acetate kinases include those enzymes that correspond to Enzyme Commission Number 2.72.1. The ACK can be native or heterologous to the recombinant yeast host cell. In some embodiments, the ACK is of prokaryotic or eukaryotic origin. In other embodiments, the ACK can be encoded by a ack gene (e.g., ACK). In some embodiments, the ACK is derived from Bifidobacterium sp., and in further embodiments from Bifidobacterium adolescentis. In such embodiments, the ACK can have the amino acid sequence of SEQ ID NO: 8, be a variant of the amino acid sequence of SEQ ID NO: 8 having ACK activity or be a fragment of the amino acid sequence of SEQ ID NO: 8 having ACK activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the ACK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 7, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 8 (a variant thereof or a fragment thereof). In some embodiments, the ACK is of prokaryotic or eukaryotic origin. In other embodiments, the ACK can be encoded by a ack gene (e.g., ACK). In some embodiments, the ACK is derived from Leuconostoc sp., and in further embodiments from Leuconostoc mesenteroides. In such embodiments, the ACK can have the amino acid sequence of SEQ ID NO: 71 , be a variant of the amino acid sequence of SEQ ID NO: 71 having ACK activity or be a fragment of the amino acid sequence of SEQ ID NO: 71 having ACK activity. The recombinant yeast host cell can include, a heterologous nucleic acidmolecule encoding the ACK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 70, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 71 (a variant thereof or a fragment thereof). In some embodiments, the ACK is of prokaryotic or eukaryotic origin. In other embodiments, the ACK can be encoded by a ack gene (e.g., ACK). In some embodiments, the ACK is derived from Oenococcus sp., and in further embodiments from Oenococcus oenii. In such embodiments, the ACK can have the amino acid sequence of SEQ ID NO: 73, be a variant of the amino acid sequence of SEQ ID NO: 73 having ACK activity or be a fragment of the amino acid sequence of SEQ ID NO: 73 having ACK activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the ACK. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 72, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 73 (a variant thereof or a fragment thereof). Additional sources of ACK that can be included in the recombinant yeast host cell of the present disclosure include, without limitation, Eschericia sp. (Escherichia coli), Lactiplantibacillus sp., Bacillus sp. (Bacillus subtilis), Clostridium sp. (Clostridium acetobutylicum), Salmonella sp. (Salmonella enterica), Aspergillus sp. (Aspergillus nidulans), Phytophthora sp. (Phytophthora ramorum), and Chlamydomonas sp. (Chlamydomonas reinhardtii).

[0043] The engineered metabolic pathway to convert fructose-6-phosphate to acetyl-coenzyme A can include, in some embodiments, a phosphotransacetylase. As such, the recombinant yeast host cell of the present disclosure can include, in such embodiments, a phosphotransacetylase. As used herein, the terms "phosphotransacetylase" and "PTA" are intended to include the enzymes capable of converting acetyl-phosphate into acetyl-coA. Phosphotransacetylases include those enzymes that correspond to Enzyme Commission Number 2.3.1.8. The PTA can be native or heterologous to the recombinant yeast host cell. In some embodiments, the PTA is of prokaryotic or eukaryotic origin. In other embodiments, the PTA can be encoded by a pta gene (e.g., PTA). In some embodiments, the PTA is derived from Bifidobacterium sp., and in further embodiments from Bifidobacterium adolescentis. In such embodiments, the PTA can have the amino acid sequence of SEQ ID NO: 6, be a variant of the amino acid sequence of SEQ ID NO: 6 having PTA activity or be a fragment of the amino acid sequence of SEQ ID NO: 6 having PTA activity. The recombinant yeast host cell can include, a heterologous nucleic acid moleculeencoding the PTA. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 5, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 6 (a variant thereof or a fragment thereof). In some embodiments, the PTA is derived from Leuconostoc sp., and in further embodiments from Leuconostoc mesenteroides. In such embodiments, the PTA can have the amino acid sequence of SEQ ID NO: 67, be a variant of the amino acid sequence of SEQ ID NO: 67 having PTA activity or be a fragment of the amino acid sequence of SEQ ID NO: 67 having PTA activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the PTA. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 66, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 67 (a variant thereof or a fragment thereof). In some embodiments, the PTA is derived from Oenococcus sp., and in further embodiments from Oenococcus oenii. In such embodiments, the PTA can have the amino acid sequence of SEQ ID NO: 69, be a variant of the amino acid sequence of SEQ ID NO: 69 having PTA activity or be a fragment of the amino acid sequence of SEQ ID NO: 69 having PTA activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the PTA. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 68, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 69 (a variant thereof or a fragment thereof). In some embodiments, the PTA is derived from Azetobacter sp., and in further embodiments from Azotobacter vinelandii. In such embodiments, the PTA can have the amino acid sequence of SEQ ID NO: 112, be a variant of the amino acid sequence of SEQ ID NO: 112 having PTA activity or be a fragment of the amino acid sequence of SEQ ID NO: 112 having PTA activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the PTA. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 111 , or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 112 (a variant thereof or a fragment thereof). In some embodiments, the PTA is derived from Lactobacillus sp., and in further embodiments from Lactobacillus plantarum. In such embodiments, the PTA can have the amino acid sequence of SEQ ID NO: 114, be a variant of the amino acid sequence of SEQ ID NO: 114 having PTA activity or be a fragment of the amino acid sequence of SEQ ID NO: 114 having PTA activity. Therecombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the PTA. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 113, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 114 (a variant thereof or a fragment thereof). In some embodiments, the PTA is derived from Bacillus sp., and in further embodiments from Bacillus subtilis. In such embodiments, the PTA can have the amino acid sequence of SEQ ID NO: 116, be a variant of the amino acid sequence of SEQ ID NO: 116 having PTA activity or be a fragment of the amino acid sequence of SEQ ID NO: 116 having PTA activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the PTA. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 115, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 116 (a variant thereof or a fragment thereof). In some embodiments, the PTA is derived from Salmonella sp., and in further embodiments from Salmonella enterica. In such embodiments, the PTA can have the amino acid sequence of SEQ ID NO: 118 or 120, be a variant of the amino acid sequence of SEQ ID NO: 118 or 120 having PTA activity or be a fragment of the amino acid sequence of SEQ ID NO: 118 or 120 having PTA activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the PTA. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 117 or 119, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 118 or 120 (a variant thereof or a fragment thereof). In some embodiments, the PTA is derived from Clostridium sp., and in further embodiments from Clostridium kluyveri. In such embodiments, the PTA can have the amino acid sequence of SEQ ID NO: 122, be a variant of the amino acid sequence of SEQ ID NO: 122 having PTA activity or be a fragment of the amino acid sequence of SEQ ID NO: 122 having PTA activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the PTA. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 121 , or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 122 (a variant thereof or a fragment thereof). Additional sources of PTA that can be included in the recombinant yeast host cell of the present disclosure include, without limitation, Phytophthora sp. (Phytophthora ramorum, Phytophthora cactorum, Phytophthora parasitica, Phytophthora idaei), Chlamydomonas sp. (Chlamydomonasreinhardtii), Globisporangium sp. (Globisporangium splendens), Clostridium sp. (Clostridium cellulolyticum, Clostridium phytofermentans), Bifidobacterium sp. (Bifidobacterium bifidum, Bifidobacterium animalis), Microcystis sp. (Microcystis aeruginosa), and Holophagae sp. (Holophagae bacterium).

[0044] In specific embodiments, the recombinant yeast host cell of the present disclosure comprises a native and / or heterologous enzyme that function in an engineered metabolic pathway to convert acetate into acetyl-coA. The recombinant yeast host cell of the present disclosure can include, in such embodiments, an acetylcoenzyme A synthetase. As used herein, the term "acetyl-coA synthetase" and "ACS" are intended to include the enzymes capable of converting acetate to acetyl -coA. Acetyl-coA synthetases include those enzymes that correspond to Enzyme Commission Number 6.2.1.1. The ACS can be native or heterologous to the recombinant yeast host cell. In some embodiments, the ACS is of prokaryotic or eukaryotic origin. In other embodiments, the ACS can be encoded by a acs1 gene (e.g., ACS1 ) or a acs2 gene (e.g., ACS2). In some embodiments, the ACS is derived from Saccharomyces sp., and in further embodiments from Saccharomyces cerevisiae. In such embodiments, the ACS can have the amino acid sequence of SEQ ID NO: 2 or 34, be a variant of the amino acid sequence of SEQ ID NO: 2 or 34 having ACS activity or be a fragment of the amino acid sequence of SEQ ID NO: 2 or 34 having ACS activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the ACS. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 1 or 33 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 2 or 34 (a variant thereof or a fragment thereof). In some embodiments, the ACS is derived from Zygosaccharomyces sp., and in further embodiments from Zygosaccharomyces bailii. In such embodiments, the ACS can have the amino acid sequence of SEQ ID NO: 30, be a variant of the amino acid sequence of SEQ ID NO: 30 having ACS activity or be a fragment of the amino acid sequence of SEQ ID NO: 30 having ACS activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the ACS. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 29 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 30 (a variant thereof or a fragment thereof). In some embodiments, the ACS is derived from Salmonella sp., and in further embodiments from Salmonella enterica. In suchembodiments, the ACS can have the amino acid sequence of SEQ ID NO: 32, be a variant of the amino acid sequence of SEQ ID NO: 32 having ACS activity or be a fragment of the amino acid sequence of SEQ ID NO: 32 having ACS activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the ACS. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 31 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 32 (a variant thereof or a fragment thereof). In some embodiments, the ACS is derived from Acetobacter sp., and in further embodiments from Acetobacter aceti. In such embodiments, the ACS can have the amino acid sequence of SEQ ID NO: 35, be a variant of the amino acid sequence of SEQ ID NO: 35 having ACS activity or be a fragment of the amino acid sequence of SEQ ID NO: 35 having ACS activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the ACS. In such embodiment, the heterologous nucleic acid molecule can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 35 (a variant thereof or a fragment thereof). Additional sources of ACS that can be included in the recombinant yeast host cell of the present disclosure include, without limitation, Aedes togoi, Aliivibrio fischeri, Amaranthus sp., Arabidopsis thaliana, Archaeoglobus fulgidus, Aspergillus nidulans, Aspergillus niger, Bacillus subtilis, Bos taurus, Bradyrhizobium japonicum, Cereibacter sphaeroides, Cryptosporidium parvum, Dunaliella tertiolecta, Escherichia coli, Euglena gracilis, Haloarcula marismortui, Homo sapiens, Hordeum vulgare, Ignicoccus hospitalis, Marmota monax, Methanosarcina acetivorans, Methanosarcina sp., Methanothermobacter thermautotrophicus, Methanothrix soehngenii, Methanothrix thermoacetophila (Uniprot A0B8F1 for exemple), Moorella thermoacetica, Mus musculus, Mus musculus, Oryctolagus cuniculus, Ovis aries, Pelotomaculum thermopropionicum, Penicillium chrysogenum, Phycomyces blakesleeanus, Pinus radiata, Pisum sativum, Populus trichocarpa, Pseudomonas putida (Uniprot Q6EMJ3 for example), Pyrobaculum aerophilum, Pyrococcus furiosus, Rattus norvegicus, Rhodotorula diobovata, Roseovarius sp., Saccharopolyspora erythraea, Spinacia oleracea, Streptomyces lividans, Taxus sp., and Zea mays.

[0045] In specific embodiments, the recombinant yeast host cell of the present disclosure comprises a native or heterologous enzyme that function in an engineered metabolic pathway to convert acetate into acetyl-coA. In such embodiments, the native or heterologous enzyme comprises an activated, upregulated or overexpressed acetyl-coA synthetase 2 (ACS2). In some embodiments, the ACS2 is derived from Saccharomyces sp., and in further embodiments from Saccharomyces cerevisiae. In such embodiments, the ACS can have the amino acid sequence of SEQ ID NO: 2, be a variant of the amino acid sequence of SEQ ID NO: 2 having ACS activity or be a fragment of the amino acid sequence of SEQ ID NO: 2 having ACS activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the ACS. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 1 or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 2 (a variant thereof or a fragment thereof). Additional sources of ACS2 that can be included in the recombinant yeast host cell of the present disclosure include, without limitation, Aedes togoi, Aliivibrio fischeri, Amaranthus sp., Arabidopsis thaliana, Archaeoglobus fulgidus, Aspergillus nidulans, Aspergillus niger, Bacillus subtilis, Bos taurus, Bradyrhizobium japonicum, Cereibacter sphaeroides, Cryptosporidium parvum, Dunaliella tertiolecta, Escherichia coli, Euglena gracilis, Haloarcula marismortui, Homo sapiens, Hordeum vulgare, Ignicoccus hospitalis, Marmota monax, Methanosarcina acetivorans, Methanosarcina sp., Methanothermobacter thermautotrophicus, Methanothrix soehngenii, Methanothrix thermoacetophila (Uniprot A0B8F1 for exemple), Moorella thermoacetica, Mus musculus, Mus musculus, Oryctolagus cuniculus, Ovis aries, Pelotomaculum thermopropionicum, Penicillium chrysogenum, Phycomyces blakesleeanus, Pinus radiata, Pisum sativum, Populus trichocarpa, Pseudomonas putida (Uniprot Q6EMJ3 for example), Pyrobaculum aerophilum, Pyrococcus furiosus, Rattus norvegicus, Rhodotorula diobovata, Roseovarius sp., Saccharopolyspora erythraea, Spinacia oleracea, Streptomyces lividans, Taxus sp., and Zea mays. In embodiments in which the recombinant yeast host cell comprises the native or heterologous enzyme comprises an activated, upregulated or overexpressed acetyl- coA synthetase 2, the recombinant yeast host cell optionally comprises a deletion in the native alcohol dehydrogenase 6 (ALD6) gene (in one or all copies). In Saccharomyces cerevisiae, the native ALD6 can have the amino acid sequence of SEQ ID NO: 110. In such embodiment, the recombinant yeast host cell can comprise a partial or complete deletion in the native ALD6 which encodes the polypeptide having the amino acid sequence of SEQ ID NO: 110. Still in Saccharomyces cerevisiae, the coding sequence of the native ald6 gene can have the nucleic acid sequence of SEQ ID NO: 109. In such embodiment, the recombinant yeast host cell can comprise apartial or complete deletion of the native ald6 gene having the nucleic acid sequence of SEQ ID NO: 109 (or a degenerate sequence of the ald6 gene encoding the amino acid sequence of SEQ ID NO: 110).

[0046] In some embodiments of the recombinant yeast host cell of the present disclosure, a native and / or heterologous enzyme that functions in an engineered non- oxidative pentose phosphate pathway is present. In such embodiment, the native and / or heterologous enzyme of the engineered non-oxidative pentose phosphate pathway is activated, upregulated, or overexpressed. Enzyme that functions in an engineered non-oxidative pentose phosphate pathway include, without limitations, a transaldolase, a transketolase, an epimerase, and an isomerase. The recombinant yeast host cell of the present disclosure can include one or more enzyme that functions in an engineered non-oxidative pentose phosphate pathway. In an embodiment, the recombinant yeast host cell of the present disclosure comprises a native and / or heterologous transaldolase that can optionally be in combination with a transketolase, an epimerase, and / or an isomerase. In an embodiment, the recombinant yeast host cell of the present disclosure comprises a native and / or heterologous transketolase that can optionally be in combination with a transaldolase, an epimerase, and / or an isomerase. In an embodiment, the recombinant yeast host cell of the present disclosure comprises a native and / or heterologous epimerase that can optionally be in combination with a transaldolase, a transketolase, and / or an isomerase. In an embodiment, the recombinant yeast host cell of the present disclosure comprises a native and / or heterologous isomerase that can optionally be in combination with a transaldolase, a transketolase, and / or an epimerase. In still yet another embodiment, the recombinant yeast host cell of the present disclosure comprises a native and / or heterologous transaldolase, transketolase, epimerase and isomerase. In some embodiments, the native and / or heterologous enzyme that functions in the engineered non-oxidative pentose phosphate pathway comprises at least two of the transaldolase, the transketolase, the epimerase, or the isomerase (e.g., transaldose and transketolase, transaldolase and epimerase, transaldolase and isomerase, transketolase and epimerase, transketolase and isomerase or epimerase and isomerase). In another embodiment, the native and / or heterologous enzyme that functions in an engineered non-oxidative pentose phosphate pathway comprises at least three of the transaldolase, the transketolase, the epimerase, or the isomerase (e.g., transaldolase, transketolase and epimerase; transaldolase, transketolase andisomerase; transketolase, epimerase and isomerase; transaldolase, epimerase and isomerase). In still another embodiment, the native and / or heterologous enzyme that functions in an engineered non-oxidative pentose phosphate pathway comprises the transaldolase, the transketolase, the epimerase, and the isomerase.

[0047] The native and / or heterologous enzyme that functions in an engineered non-oxidative pentose phosphate pathway can comprise a transaldolase. The recombinant yeast host cell of the present disclosure can include a transaldolase. As used herein, the terms "transaldolase" or "TAL" are intended to include the enzymes capable of converting glyceraldehyde 3-phosphate into erythrose 4-phosphate as well as those capable of converting sedoheptulose 7-phosphate into fructose 6-phosphate. Transaldolases include those enzymes that correspond to Enzyme Commission Number 2.2.1 .2. The TAL can be native or heterologous to the recombinant yeast host cell. The recombinant yeast host cell can include a native TAL and optionally in combination a heterologous TAL. In some embodiments, the TAL is of prokaryotic or eukaryotic origin. In other embodiments, the TAL can be encoded by a tai gene (e.g., TAL). In some embodiments, the TAL is derived from Saccharomyces sp., and in further embodiments from Saccharomyces cerevisiae. In such embodiments, the TAL can have the amino acid sequence of SEQ ID NO: 14, be a variant of the amino acid sequence of SEQ ID NO: 14 having TAL activity or be a fragment of the amino acid sequence of SEQ ID NO: 14 having TAL activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the TAL. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 13, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 14 (a variant thereof or a fragment thereof). Other sources TAL that can be included in the recombinant yeast host cell of the present disclosure include, without limitation Acidithiobacillus ferrooxidans, Arthrobacter sp., Bifidobacterium bifidum, Blastobotrys adeninivorans, Blastobotrys adeninivorans (Uniprot Q0E4W0 for example), Bos taurus, Carcinus maenas, Chlorella sp., Chromatium sp., Clostridium acetobutylicum, Cryptococcus neoformans, Cyberlindnera jadinii, Dictyostelium discoideum, Escherichia coli, Euglena sp., Francisella tularensis (Uniprot Q5NFX0 for example), Fusarium oxysporum, Gluconobacter oxydans (Uniprot Q76EM7 for example), Homo sapiens, Methanocaldococcus jannaschii, Moniliella megachiliensis, Mus musculus, Musca domestica, Ogataea polymorpha, Oryctolagus cuniculus, Oryza sativa,Prosthecochloris vibrioformis f. thiosulfatophilum, Rattus norvegicus, Saccharomyces pastorianus Scheffersomyces stipitis, Solanum lycopersicum, Spinacia oleracea, Tetranychus telarius, Thermodesulfobium acidiphilum (Uniprot A0A2R4VZ98 for example), Thermoplasma acidophilum, and Thermotoga maritima (Uniprot Q9WYD1 for example).

[0048] The native and / or heterologous enzyme that functions in an engineered non-oxidative pentose phosphate pathway can comprise a transketolase. The recombinant yeast host cell of the present disclosure can include a transketolase. As used herein, the terms "transketolase" and "TKL" are intended to include the enzymes capable of converting ribose 5-phosphate into glyceraldehyde 3-phosphate, fructose 6-phosphate into xylulose 5-phosphate, xylulose 5-phoshate into sedoheptulose 7- phosphate, and / or glyceraldehyde 3-phosphate into erythrose 4-phosphate. Transketolases include those enzymes that correspond to Enzyme Commission Number 2.2.1 .1 . The TKL can be native or heterologous to the recombinant yeast host cell. The recombinant yeast host cell can include a native TKL and optionally in combination a heterologous TKL. In some embodiments, the TKL is of prokaryotic or eukaryotic origin. In other embodiments, the TKL can be encoded by a tkl1 gene (e.g., TKL1 ). In some embodiments, the TKL is derived from Saccharomyces sp., and in further embodiments from Saccharomyces cerevisiae. In such embodiments, the TKL can have the amino acid sequence of SEQ ID NO: 12, be a variant of the amino acid sequence of SEQ ID NO: 12 having TKL activity or be a fragment of the amino acid sequence of SEQ ID NO: 12 having TKL activity. The recombinant yeast host cell can include, a heterologous nucleic acid molecule encoding the TKL. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 11 , or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 12 (a variant thereof or a fragment thereof). Additional sources of TKL that can be included in the recombinant yeast host cell include, without limitation, Alcaligenes faecalis, Arabidopsis thaliana, Bacillus methanolicus, Cereibacter sphaeroides, Chlamydomonas reinhardtii (Uniprot A8IAN1 for example), Chromobacterium violaceum, Craterostigma plantagineum, Cucumis sativus, Cyberlindnera jadinii, Escherichia coli, Geobacillus stearothermophilus, Homo sapiens, Lactiplantibacillus pentosus, Leishmania Mexicana, Ligilactobacillus salivarius (Uniprot Q1WQU8 for example), Moniliella megachiliensis (Uniprot A0A1 L7NSX5 or A0A1 L7NSY2 for example), Mus musculus (Uniprot P40142 forexample), Mycobacterium tuberculosis (Uniprot P9WG25), Neoporphyra haitanensis, Oryctolagus cuniculus, Saccharum officinarums, Plasmodium falciparum, Rattus norvegicus, Rhodopseudomonas palustris, Salmonella enterica subsp. enterica serovar Typhimurium, Scheffersomyces stipites, Spinacia oleracea, Sus scrofa, Triticum aestivum, and Trypanosoma brucei.

[0049] The native and / or heterologous enzyme that functions in an engineered non-oxidative pentose phosphate pathway can comprise an epimerase. The recombinant yeast host cell of the present disclosure can include an epimerase. As used herein, the terms "epimerase" and "RPE" are intended to include the enzymes capable of converting ribulose 5-phosphate into xylulose 5-phosphate and / or xylulose 5-phosphate to ribulose 5-phosphate. Epimerases include those enzymes that correspond to Enzyme Commission Number 5.1.3.1. The RPE can be native or heterologous to the recombinant yeast host cell. The recombinant yeast host cell can include a native RPE and optionally in combination a heterologous RPE. In some embodiments, the RPE is of prokaryotic or eukaryotic origin. In other embodiments, the RPE can be encoded by a rpe1 gene (e.g., RPE1 ). In some embodiments, the RPE is derived from Saccharomyces sp., and in further embodiments from Saccharomyces cerevisiae. In such embodiments, the RPE can have the amino acid sequence of SEQ ID NO: 16, be a variant of the amino acid sequence of SEQ ID NO: 16 having RPE activity or be a fragment of the amino acid sequence of SEQ ID NO: 16 having RPE activity. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 15, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 16 (a variant thereof or a fragment thereof). Additional sources of RPE that can be included in the recombinant yeast host cell include, without limitation, Bacillus methanolicus (Uniprot I3DTN4, I3DTP3, or I3DZ65, for example), Bos taurus, Capsicum annuum, Cupriavidus necator, Escherichia coli, Homo sapiens, Lacticaseibacillus casei, Oryctolagus cuniculus, Oryza sativa, Pisum sativum, Rattus norvegicus, Solanum tuberosum, Spinacia oleracea, Streptococcus pyogenes (Uniprot Q9A1 H8, for example), and Synechocystis sp. (Uniprot P74061 , for example).

[0050] The native and / or heterologous enzyme that functions in an engineered non-oxidative pentose phosphate pathway can comprise an isomerase. The recombinant yeast host cell of the present disclosure can include an isomerase. As used herein, the terms "isomerase" and "RKI" are intended to include the enzymescapable of converting ribulose 5-phosphate into ribose 5-phosphate, and / or ribose 5- phosphate into ribulose 5-phosphate. Isomerases include those enzymes that correspond to Enzyme Commission Number 5.1.3.6. The RKI can be native or heterologous to the recombinant yeast host cell. The recombinant yeast host cell can include a native RKI and optionally in combination a heterologous RKI In some embodiments, the RKI is of prokaryotic or eukaryotic origin. In other embodiments, the RKI can be encoded by a rki1 gene (e.g., RKI1 ). In some embodiments, the RKI is derived from Saccharomyces sp., and in further embodiments from Saccharomyces cerevisiae. In such embodiments, the RKI can have the amino acid sequence of SEQ ID NO: 18, be a variant of the amino acid sequence of SEQ ID NO: 18 having RKI activity or be a fragment of the amino acid sequence of SEQ ID NO: 18 having RKI activity. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 17, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 18 (a variant thereof or a fragment thereof). Additional sources of RKI that can be included in the recombinant yeast host cell include, without limitation, Acetivibrio thermocellus, Arabidopsis thaliana (Uniprot Q9ZU38, for example), Bos taurus, Chromatium sp., Clostridioides difficile (Uniprot AM1 80355, for example), Coccidioides immitis (Uniprot P0CL19, for example), Cyberlindnera jadinii, Echinococcus granulosus, Escherichia coli (Uniprot P0A7Z0, for example), Halothiobacillus neapolitanus, Homo sapiens (Uniprot P49247, for example), Klebsiella aerogenes, Leishmania donovani (Uniprot G9JM00, for example), Leishmania infantum (Uniprot A4I3S4, for example), Leishmania major (Uniprot Q4Q869, for example), Macrotyloma uniflorum, Methanocaldococcus jannaschii (Uniprot Q58998, for example), Mycobacterium tuberculosis (Uniprot P9WKD7, for example), Pediococcus pentosaceus, Pisum sativum, Plasmodium falciparum, Pseudothermotoga lettingae, Pyrococcus horikoshii (Uniprot 050083, for example), Rattus norvegicus, Rhodospirillum rubrum, Spinacia oleracea, Streptococcus mutans (Uniprot Q8DRS5 or Swissprot Q8DTT9, for example), Streptococcus pneumoniae, Sus scrofa, Synechococcus elongatus, Thermotoga maritima (Uniprot Q9X0G9, for example), Thermus thermophilus, Thiobacillus thioparus, Trypanosoma brucei, Trypanosoma cruzi (Uniprot Q4CQE2, for example), and Vibrio vulnificus (Uniprot Q7MHL9, for example).

[0051] In order to further increase the production of acetyl-coenzyme A, it is possible to engineer a metabolic pathway in the recombinant yeast host cell to convertpantothenate into coenzyme A. In order to do so, it is possible to increase or allow the expression of a pantothenate transporter, like the plasma membrane proton- pantothenate symporter FEN2. As used herein, the terms "plasma membrane proton- pantothenate symporter" and "FEN2" are intended to include the transporters capable of relaying across the cellular membrane pantothenate and protons (H+). Plasma membrane proton-pantothenate symporters include those proteins that correspond to Transporter Classification Database 2. A.1.14.18. The FEN2 can be native or heterologous to the recombinant yeast host cell. The recombinant yeast host cell can include a native FEN2 and optionally in combination a heterologous FEN2. In some embodiments, the FEN2 is of prokaryotic or eukaryotic origin. In other embodiments, the FEN2 can be encoded by a fen2 gene (e.g., FEN2). In some embodiments, the FEN2 is derived from Saccharomyces sp., and in further embodiments from Saccharomyces cerevisiae. In such embodiments, the FEN2 can have the amino acid sequence of SEQ ID NO: 26, be a variant of the amino acid sequence of SEQ ID NO: 26 having FEN2 activity or be a fragment of the amino acid sequence of SEQ ID NO: 26 having FEN2 activity. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 25, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 26 (a variant thereof or a fragment thereof).

[0052] Alternatively or in combination, the engineered metabolic pathway in the recombinant yeast host cell to convert pantothenate into coenzyme A can include, in some embodiments, a pantothenate kinase, such as CAB1 . As shown in Figure 3, the pantothenate kinase CAB1 is the first step in the conversion of pantothenate into coenzyme A. As used herein, the terms "pantothenate kinase" and "CAB1" are intended to include the enzymes capable of phosphorylating pantothenate into 4’- phosphopentothenate. Pantothenate kinases include enzymes that correspond to Enzyme Commission Number 2.7.1.33. The CAB1 can be native or heterologous to the recombinant yeast host cell. The recombinant yeast host cell can include a native CAB1 and optionally in combination a heterologous CAB1. In some embodiments, the CAB1 is of prokaryotic or eukaryotic origin. In other embodiments, the CAB1 can be encoded by a cab1 gene (e.g., CAB1 ). In some embodiments, the CAB1 is derived from Saccharomyces sp., and in further embodiments from Saccharomyces cerevisiae. In such embodiments, the CAB1 can have the amino acid sequence of SEQ ID NO: 28, be a variant of the amino acid sequence of SEQ ID NO: 28 havingCAB1 activity (such as, for example, the CAB1W331 Rvariant) or be a fragment of the amino acid sequence of SEQ ID NO: 28 having CAB1 activity. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 27, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 28 (a variant thereof or a fragment thereof). In some embodiments, the CAB1 can have the amino acid sequence of SEQ ID NO: 108, be a variant of the amino acid sequence of SEQ ID NO: 108 having CAB1 activity or be a fragment of the amino acid sequence of SEQ ID NO: 108 having CAB1 activity. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleic acid sequence of SEQ ID NO: 107, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 108 (a variant thereof or a fragment thereof). Additional sources of CAB1 that can be included in the recombinant yeast host cell include, without limitation, Arabidopsis thaliana, Aspergillus nidulans (Uniprot 093921 , for example), Bacillus anthracis (Uniprot Q81VX4, for example), Bacillus subtilis, Brassica napus, Cory nebacteri urn ammoniagenes, Drosophila melanogaster, Entamoeba histolytica (Uniprot B1 N2P3, for example), Enterococcus faecalis (Uniprot Q839J7, for example), Escherichia coli (Uniprot P0A6I3, for example), Gorilla beringei, Homo sapiens (Uniprot Q9BZ23, Q8TE04, or Q9H999, for example), Klebsiella pneumoniae (Uniprot B5XYG3 for example), Lactiplantibacillus plantarum, Micrococcus luteus, Morganella morganii, Mus musculus (Uniprot Q8K4K6, or Q8R2W9, for example), Mycobacterium tuberculosis (Uniprot P9WPA7, or P9WPA1 , for example), Orchesella cincta, Picrophilus torridus (Uniprot Q6L2I5, for example), Plasmodium falciparum (Uniprot Q8ILP4, for example), Pseudomonas aeruginosa (Uniprot Q9HWC1 , for example), Pseudomonas putida (Uniprot V5XWU6, for example), Rattus norvegicus (Uniprot Q923S8, for example), Spinacia oleracea, Staphylococcus aureus (Uniprot Q6G7I0, or A0A167Z3Z6, for example), Streptomyces peucetius (Uniprot D2K764, for example), Thermococcus kodakarensis (Uniprot Q5JHF1 , for example), and Thermotoga maritima (Uniprot Q9WZY5, for example).

[0053] In some embodiments, the recombinant yeast host cell can include a native and / or heterologous enzyme that functions in an engineered metabolic pathway to convert acetyl-coenzyme A and acetate to acetone. In such embodiment, the engineered metabolic pathway to convert acetyl-coenzyme A and acetate to acetone is activated, upregulated, or overexpressed. The engineered metabolic pathway toconvert acetyl-coenzyme A and acetate to acetone comprises at least one of a thiolase, a coenzyme A transferase, a acetoacetyl coenzyme A hydrolase or an acetoacetate decarboxylase. In some embodiments, the engineered metabolic pathway to convert acetyl-coenzyme A and acetate to acetone comprises at least two of a thiolase, a coenzyme A transferase, a acetoacetyl coenzyme A hydrolase or an acetoacetate decarboxylase (a thiolase and a coenzyme A transferase; a thiolase and acetoacetyl coenzyme A hydrolase; a thiolase and an acetoacetate decarboxylase; a coenzyme A transferase and a acetoacetyl coenzyme A hydrolase; a coenzyme A transferase and an acetoacetate decarboxylase; a acetoacetyl coenzyme A hydrolase and an acetoacetate decarboxylase). In some embodiments, the engineered metabolic pathway to convert acetyl-coenzyme A and acetate to acetone comprises at least three of a thiolase, a coenzyme A transferase, a acetoacetyl coenzyme A hydrolase or an acetoacetate decarboxylase (a thiolase, a coenzyme A transferase, and a acetoacetyl coenzyme A hydrolase; a thiolase, a acetoacetyl coenzyme A hydrolase and an acetoacetate decarboxylase; a coenzyme A transferase, a acetoacetyl coenzyme A hydrolase, and an acetoacetate decarboxylase). In some embodiments, the engineered metabolic pathway to convert acetyl-coenzyme A and acetate to acetone comprises a thiolase, a coenzyme A transferase, a acetoacetyl coenzyme A hydrolase, and an acetoacetate decarboxylase.

[0054] In some embodiments, the engineered metabolic pathway to convert acetyl-coenzyme A and acetate to acetone comprises a thiolase. As used herein, the terms "thiolase", “THL”, “ERG10” and "PHAA" are intended to include the enzymes capable of converting acetyl-coA into acetoacetyl-coA. Thiolases include enzymes that correspond to Enzyme Commission Number 2.3.1.9. The thiolase can be native or heterologous to the recombinant yeast host cell. The recombinant yeast host cell can include a native thiolase and optionally in combination a heterologous thiolase. In some embodiments, the thiolase is of prokaryotic or eukaryotic origin. In other embodiments, the thiolase can be encoded by a thl gene (e.g., THL), an erg10 gene (e.g., ERG10), or a phaA gene (e.g., PHAA). In some embodiments, the thiolase is derived from Saccharomyces sp., and in further embodiments from Saccharomyces cerevisiae. In such embodiments, the thiolase can have the amino acid sequence of SEQ ID NO: 10, be a variant of the amino acid sequence of SEQ ID NO: 10 having thiolase activity or be a fragment of the amino acid sequence of SEQ ID NO: 10 having thiolase activity. In such embodiment, the heterologous nucleic acid molecule can comprise the nucleicacid sequence of SEQ ID NO: 9, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 10 (a variant thereof or a fragment thereof). In some embodiments, the thiolase is derived from Clostridium sp., and in further embodiments from Clostridium acetobutylicum. In such embodiments, the thiolase can have the amino acid sequence of SEQ ID NO: 74, be a variant of the amino acid sequence of SEQ ID NO: 74 having thiolase activity or be a fragment of the amino acid sequence of SEQ ID NO: 74 having thiolase activity. In such embodiment, the heterologous nucleic acid molecule can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 74 (a variant thereof or a fragment thereof). In some embodiments, the thiolase is from Clostridium kluyveri. In such embodiments, the thiolase can have the amino acid sequence of SEQ ID NO: 76, be a variant of the amino acid sequence of SEQ ID NO: 76 having thiolase activity or be a fragment of the amino acid sequence of SEQ ID NO: 76 having thiolase activity. In such embodiment, the heterologous nucleic acid molecule can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 76 (a variant thereof or a fragment thereof). In some embodiments, the thiolase is derived from Cupriavidus sp., and in further embodiments from Cupriavidus necator. In such embodiments, the thiolase can have the amino acid sequence of SEQ ID NO: 75, be a variant of the amino acid sequence of SEQ ID NO: 75 having thiolase activity or be a fragment of the amino acid sequence of SEQ ID NO: 75 having thiolase activity. In such embodiment, the heterologous nucleic acid molecule can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 75 (a variant thereof or a fragment thereof). In some embodiments, the thiolase is derived from Yarrowia sp., and in further embodiments from Yarrowia Hpolytica. In such embodiments, the thiolase can have the amino acid sequence of SEQ ID NO: 77, be a variant of the amino acid sequence of SEQ ID NO: 77 having thiolase activity or be a fragment of the amino acid sequence of SEQ ID NO: 77 having thiolase activity. In such embodiment, the heterologous nucleic acid molecule can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 77 (a variant thereof or a fragment thereof). In some embodiments, the thiolase is derived from Thermoanaerobacterium sp., and in further embodiments from Thermoanaerobacterium thermosaccharolyticum. In such embodiments, the thiolase can have the amino acid sequence of SEQ ID NO: 78, be a variant of the amino acid sequence of SEQ ID NO: 78 having thiolase activity or be a fragment of the amino acidsequence of SEQ ID NO: 78 having thiolase activity. In such embodiment, the heterologous nucleic acid molecule can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 78 (a variant thereof or a fragment thereof). In some embodiments, the thiolase is derived from Saccog / ossus sp., and in further embodiments from Saccog / ossus kowalevskii. In such embodiments, the thiolase can have the amino acid sequence of SEQ ID NO: 79, be a variant of the amino acid sequence of SEQ ID NO: 79 having thiolase activity or be a fragment of the amino acid sequence of SEQ ID NO: 79 having thiolase activity. In such embodiment, the heterologous nucleic acid molecule can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 79 (a variant thereof or a fragment thereof). In some embodiments, the thiolase is derived from Strongylocentrotus sp., and in further embodiments from Strongylocentrotus purpuratus. In such embodiments, the thiolase can have the amino acid sequence of SEQ ID NO: 80, be a variant of the amino acid sequence of SEQ ID NO: 80 having thiolase activity or be a fragment of the amino acid sequence of SEQ ID NO: 80 having thiolase activity. In such embodiment, the heterologous nucleic acid molecule can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 80 (a variant thereof or a fragment thereof). In some embodiments, the thiolase is derived from Paenibacillus sp., and in further embodiments from Paenibacillus polymyxa. In such embodiments, the thiolase can have the amino acid sequence of SEQ ID NO: 81 , be a variant of the amino acid sequence of SEQ ID NO: 81 having thiolase activity or be a fragment of the amino acid sequence of SEQ ID NO: 81 having thiolase activity. In such embodiment, the heterologous nucleic acid molecule can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 81 (a variant thereof or a fragment thereof). Additional sources of the thiolase that can be included in the recombinant yeast host cell include, without limitation, Arabidopsis thaliana (Uniprot Q8S4Y1 or Q9FIK7, for example), Aspergillus fumigates (Uniprot B0XMC1 , for example), Bacillus subtilis, Bacopa monnieri (Uniprot D9U856, for example), Bos taurus, Bradyrhizobium japonicum, Candida tropicalis, Catharanthus roseus, Caulobacter vibrioides, Clonorchis sinensis (Uniprot G7YHN5, for example), Dictyostelium discoideum (Uniprot Q86AD9, for example), Enterococcus faecalis, Escherichia coli (Uniprot P76461 , for example), Euphorbia helioscopia (Uniprot A0A0M4F9H9, for example), Gallus gallus (Uniprot F1 NT20, for example), Ginkgo biloba (Uniprot A0A1 S6KJS1 , for example),Halobacterium sp., Haloferax mediterranei (Uniprot I3R3D1 , I3R3D0, I3RA72, or I3RA71 , for example), Helianthus annuus (Uniprot D2IH11 , for example), Homo sapiens (Uniprot Q9BWD1 , for example), Medicago sativa (Uniprot D0EUY6, for example), Metallosphaera sedula (Uniprot A4YEH9, for example), Methanothermococcus thermolithotrophicus (Uniprot A0A384E138, for example), Mycolicibacterium smegmatis, Ostrinia scapulalis (Uniprot B7XEI5, for example), Pyricularia oryzae, Pyrobaculum neutrophilum (Uniprot B1YB71 , for example), Rattus norvegicus, Rhizobium sp., Sanghuangporus baumii, Therm us thermophilus, Vitis vinifera x Vitis riparia, and Zoogloea ramigera (Uniprot P07256 or P07097, for example).

[0055] In some embodiments, the engineered metabolic pathway to convert acetyl-coenzyme A and acetate to acetone comprises a coenzyme A transferase. As used herein, the terms "coenzyme A transferase", “coA transferase”, “CFTA / CTFB”, and “ATOA / ATOD” are intended to include the enzymes (or enzyme moieties) capable of converting acetoacetyl-coA and acetate into acetyl-coA and acetoacetate. Coenzyme A transferases include enzymes that correspond to Enzyme Commission Number 2.8.3.8. The coA transferase can be a monomer or a dimer. The coA transferase can be native or heterologous to the recombinant yeast host cell. The recombinant yeast host cell can include a native coA transferase and optionally in combination a heterologous coA transferase. In some embodiments, the coA transferase is of prokaryotic or eukaryotic origin. In other embodiments, the coA transferase can be encoded by the ctfa and ctfb genes (e.g., CTFA / CTFB), or by the atoA and atoD genes (e.g., ATOA / ATOD). In some embodiments, the coA transferase is derived from Alkaliphilus sp., and in further embodiments from Alkaliphilus metalliredigens. In such embodiments, the coA transferase can include a first polypeptide (CTFA) having the amino acid sequence of SEQ ID NO: 20, being a variant of the amino acid sequence of SEQ ID NO: 20 having coA transferase activity (in the presence of CFTB) or being a fragment of the amino acid sequence of SEQ ID NO: 20 having coA transferase activity (in the presence of CFTB). In such embodiment, the heterologous nucleic acid molecule encoding this first polypeptide can comprise the nucleic acid sequence of SEQ ID NO: 19, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 20 (a variant thereof or a fragment thereof). Alternatively or in combination, the coA transferase can include a second polypeptide (CTFB) having the amino acid sequence of SEQ ID NO: 22, being a variantof the amino acid sequence of SEQ ID NO: 22 having coA transferase activity (in the presence of CFTA) or being a fragment of the amino acid sequence of SEQ ID NO: 22 having coA transferase activity (in the presence of CFTA). In such embodiment, the heterologous nucleic acid molecule encoding this second polypeptide can comprise the nucleic acid sequence of SEQ ID NO: 21 , or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 22 (a variant thereof or a fragment thereof). In some embodiments, the coA transferase is derived from Clostridium sp., and in further embodiments from Clostridium acetobutylicum. In such embodiments, the coA transferase can include a first polypeptide (CTFA) having the amino acid sequence of SEQ ID NO: 82, being a variant of the amino acid sequence of SEQ ID NO: 82 having coA transferase activity (in the presence of CFTB) or being a fragment of the amino acid sequence of SEQ ID NO: 82 having coA transferase activity (in the presence of CFTB). In such embodiment, the heterologous nucleic acid molecule encoding this first polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 82 (a variant thereof or a fragment thereof). Alternatively or in combination, the coA transferase can include a second polypeptide (CTFB) having the amino acid sequence of SEQ ID NO: 83, being a variant of the amino acid sequence of SEQ ID NO: 83 having coA transferase activity (in the presence of CFTA) or being a fragment of the amino acid sequence of SEQ ID NO: 83 having coA transferase activity (in the presence of CFTA). In such embodiment, the heterologous nucleic acid molecule encoding this second polypeptide a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 83 (a variant thereof or a fragment thereof). In some embodiments, the coA transferase is derived from Thermosipho sp., and in further embodiments from Thermosipho melanesiensis. In such embodiments, the coA transferase can include a first polypeptide (CTFA) having the amino acid sequence of SEQ ID NO: 84, being a variant of the amino acid sequence of SEQ ID NO: 84 having coA transferase activity (in the presence of CFTB) or being a fragment of the amino acid sequence of SEQ ID NO: 84 having coA transferase activity (in the presence of CFTB). In such embodiment, the heterologous nucleic acid molecule encoding this first polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 84 (a variant thereof or a fragment thereof). Alternatively or in combination, the coA transferase can include a second polypeptide (CTFB) having the amino acid sequence of SEQ ID NO: 85, being a variant of the amino acid sequence of SEQ ID NO: 85 having coAtransferase activity (in the presence of CFTA) or being a fragment of the amino acid sequence of SEQ ID NO: 85 having coA transferase activity (in the presence of CFTA). In such embodiment, the heterologous nucleic acid molecule encoding this second polypeptide a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 85 (a variant thereof or a fragment thereof). In some embodiments, the coA transferase is derived from Escherichia sp., and in further embodiments from Escherichia coli. In such embodiments, the coA transferase can include a first polypeptide (CTFA) having the amino acid sequence of SEQ ID NO: 86, being a variant of the amino acid sequence of SEQ ID NO: 86 having coA transferase activity (in the presence of CFTB) or being a fragment of the amino acid sequence of SEQ ID NO: 86 having coA transferase activity (in the presence of CFTB). In such embodiment, the heterologous nucleic acid molecule encoding this first polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 86 (a variant thereof or a fragment thereof). Alternatively or in combination, the coA transferase can include a second polypeptide (CTFB) having the amino acid sequence of SEQ ID NO: 87, being a variant of the amino acid sequence of SEQ ID NO: 87 having coA transferase activity (in the presence of CFTA) or being a fragment of the amino acid sequence of SEQ ID NO: 87 having coA transferase activity (in the presence of CFTA). In such embodiment, the heterologous nucleic acid molecule encoding this second polypeptide a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 87 (a variant thereof or a fragment thereof). In some embodiments, the coA transferase is derived from Paenibacillus sp., and in further embodiments from Paenibacillus polymyxa. In such embodiments, the coA transferase can include a first polypeptide (CTFA) having the amino acid sequence of SEQ ID NO: 88, being a variant of the amino acid sequence of SEQ ID NO: 88 having coA transferase activity (in the presence of CFTB) or being a fragment of the amino acid sequence of SEQ ID NO: 88 having coA transferase activity (in the presence of CFTB). In such embodiment, the heterologous nucleic acid molecule encoding this first polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 88 (a variant thereof or a fragment thereof). Alternatively or in combination, the coA transferase can include a second polypeptide (CTFB) having the amino acid sequence of SEQ ID NO: 89, being a variant of the amino acid sequence of SEQ ID NO: 89 having coA transferase activity (in the presence of CFTA) or being a fragment of the amino acid sequence of SEQ ID NO: 89 having coAtransferase activity (in the presence of CFTA). In such embodiment, the heterologous nucleic acid molecule encoding this second polypeptide a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 89 (a variant thereof or a fragment thereof). In some embodiments, the coA transferase is derived from Clostridium sp., and in further embodiments from Clostridium beijerinckii. In such embodiments, the coA transferase can include a first polypeptide (CTFA) having the amino acid sequence of SEQ ID NO: 90, being a variant of the amino acid sequence of SEQ ID NO: 90 having coA transferase activity (in the presence of CFTB) or being a fragment of the amino acid sequence of SEQ ID NO: 90 having coA transferase activity (in the presence of CFTB). In such embodiment, the heterologous nucleic acid molecule encoding this first polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 90 (a variant thereof or a fragment thereof). Alternatively or in combination, the coA transferase can include a second polypeptide (CTFB) having the amino acid sequence of SEQ ID NO: 91 , being a variant of the amino acid sequence of SEQ ID NO: 91 having coA transferase activity (in the presence of CFTA) or being a fragment of the amino acid sequence of SEQ ID NO: 91 having coA transferase activity (in the presence of CFTA). In such embodiment, the heterologous nucleic acid molecule encoding this second polypeptide a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 91 (a variant thereof or a fragment thereof). In some embodiments, the coA transferase is derived from Clostridium saccharoperbutylacetonicum. In such embodiments, the coA transferase can include a first polypeptide (CTFA) having the amino acid sequence of SEQ ID NO: 92, being a variant of the amino acid sequence of SEQ ID NO: 92 having coA transferase activity (in the presence of CFTB) or being a fragment of the amino acid sequence of SEQ ID NO: 92 having coA transferase activity (in the presence of CFTB). In such embodiment, the heterologous nucleic acid molecule encoding this first polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 92 (a variant thereof or a fragment thereof). Alternatively or in combination, the coA transferase can include a second polypeptide (CTFB) having the amino acid sequence of SEQ ID NO: 93, being a variant of the amino acid sequence of SEQ ID NO: 93 having coA transferase activity (in the presence of CFTA) or being a fragment of the amino acid sequence of SEQ ID NO: 93 having coA transferase activity (in the presence of CFTA). In such embodiment, the heterologous nucleic acid molecule encoding this second polypeptide a degenerate nucleic acidsequence encoding the amino acid sequence of SEQ ID NO: 93 (a variant thereof or a fragment thereof). In some embodiments, the coA transferase is derived from Acetoanaerobium sp., and in further embodiments from Acetoanaerobium sticklandii. In such embodiments, the coA transferase can include a first polypeptide (CTFA) having the amino acid sequence of SEQ ID NO: 94, being a variant of the amino acid sequence of SEQ ID NO: 94 having coA transferase activity (in the presence of CFTB) or being a fragment of the amino acid sequence of SEQ ID NO: 94 having coA transferase activity (in the presence of CFTB). In such embodiment, the heterologous nucleic acid molecule encoding this first polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 94 (a variant thereof or a fragment thereof). Alternatively or in combination, the coA transferase can include a second polypeptide (CTFB) having the amino acid sequence of SEQ ID NO: 95, being a variant of the amino acid sequence of SEQ ID NO: 95 having coA transferase activity (in the presence of CFTA) or being a fragment of the amino acid sequence of SEQ ID NO: 95 having coA transferase activity (in the presence of CFTA). In such embodiment, the heterologous nucleic acid molecule encoding this second polypeptide a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 95 (a variant thereof or a fragment thereof). In some embodiments, the coA transferase is derived from Brevibacillus sp., and in further embodiments from Brevibacillus laterosporus. In such embodiments, the coA transferase can include a first polypeptide (CTFA) having the amino acid sequence of SEQ ID NO: 96, being a variant of the amino acid sequence of SEQ ID NO: 96 having coA transferase activity (in the presence of CFTB) or being a fragment of the amino acid sequence of SEQ ID NO: 96 having coA transferase activity (in the presence of CFTB). In such embodiment, the heterologous nucleic acid molecule encoding this first polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 96 (a variant thereof or a fragment thereof). Alternatively or in combination, the coA transferase can include a second polypeptide (CTFB) having the amino acid sequence of SEQ ID NO: 97, being a variant of the amino acid sequence of SEQ ID NO: 97 having coA transferase activity (in the presence of CFTA) or being a fragment of the amino acid sequence of SEQ ID NO: 97 having coA transferase activity (in the presence of CFTA). In such embodiment, the heterologous nucleic acid molecule encoding this second polypeptide a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 97 (a variant thereof or a fragment thereof).Additional sources of coA transferase that can be included in the recombinant yeast host cell include, without limitation, Acetobacter aceti (Uniprot B3EY95, for example), Anaerobutyricum hallii (Uniprot Q2QIH1 or D2WEY8, for example), Anaerostipes caccae (Uniprot Q2QB27 or B0MC58, for example), Butyricicoccus porcorum, Butyrivibrio fibrisolvens (Uniprot D2WEY7, for example), Coprococcus sp.;Faecalibacterium prausnitzii (Uniprot Q2QIH0, A8SFP6, C7H5K4, or D2WEZ2, for example), Megasphaera elsdenii, Roseburia hominis (Uniprot Q2TME9, for example), Roseburia intestinalis (Uniprot C7GB37, for example), Roseburia inulinivorans (Uniprot D2WEY6, for example), Thermoanaerobacterium saccharolyticum, Trypanosoma brucei, Eubacterium nodatum, and Eubacterium rectale (Uniprot D2WEY1 , for example).

[0056] In some embodiments, the engineered metabolic pathway to convert acetyl-coenzyme A and acetate to acetone comprises a hydroxymethylglutaryl- coenzyme A synthase and a hydroxymethylglutaryl-coenzyme A lyase. As used herein, the terms “hydroxymethylglutaryl-coenzyme A synthase” or “HMG-CoA synthase” are intended to include the enzymes capable of converting acetyl-coenzyme A and acetoacetyl-coenzyme A into (S)-3-hydroxy-3-methylglutaryl-coenzyme A and coenzyme A. Hydroxymethylglutaryl-coenzyme A synthases include enzymes that correspond to Enzyme Commission Number 2.3.3.10. The hydroxymethylglutaryl- coenzyme A synthase can be native or heterologous to the recombinant yeast host cell. The recombinant yeast host cell can include a native hydroxymethylglutaryl- coenzyme A synthase and optionally in combination with a heterologous hydroxymethylglutaryl-coenzyme A synthase. In some embodiments, the hydroxymethylglutaryl-coenzyme A synthase is of prokaryotic or of eukaryotic origin. In some embodiments, the hydroxymethylglutaryl-coenzyme A synthase is derived from Saccharomyces sp., and in further embodiments, from Saccharomyces cerevisiae. In such embodiments, the hydroxymethylglutaryl-coenzyme A synthase can include a polypeptide having the amino acid sequence of SEQ ID NO: 124, be a variant of the amino acid sequence of SEQ ID NO: 124 having HMG-CoA synthase activity or be a fragment of the amino acid sequence of SEQ ID NO: 124 having HMG- CoA synthase activity. In such embodiment, the heterologous nucleic acid molecule encoding this polypeptide can comprise the nucleic acid sequence of SEQ ID NO: 123, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 124 (a variant thereof or a fragment thereof). As used herein, the terms“hydroxymethylglutaryl-coenzyme A lyase” and “HMG-CoA lyase” are intented to include the enzymes capable of converting (S)-3-Hydroxy-3-methylglutaryl-coenzyme A in acetyl-coenzyme A and acetoacetate. Hydroxymethylglutaryl-coenzyme A lyases include enzymes that correspond to Enzyme Commission Number 4.1.3.4. The hydroxymethylglutaryl-coenzyme A lyase can be native or heterologous to the recombinant yeast host cell. The recombinant yeast host cell can include a native hydroxymethylglutaryl-coenzyme A lyase and optionally in combination with a heterologous hydroxymethylglutaryl-coenzyme A lyase. In some embodiments, the hydroxymethylglutaryl-coenzyme A lyase is of prokaryotic or of eukaryotic origin. In some embodiments, the hydroxymethylglutaryl-coenzyme A lyase is derived from Danio sp., and in further embodiments, from Danio reiro. In such embodiments, the hydroxymethylglutaryl-coenzyme A lyase can include a polypeptide having the amino acid sequence of SEQ ID NO: 126, be a variant of the amino acid sequence of SEQ ID NO: 126 having HMG-CoA lyase activity or be a fragment of the amino acid sequence of SEQ ID NO: 126 having HMG-CoA lyase activity. In such embodiment, the heterologous nucleic acid molecule encoding this polypeptide can comprise the nucleic acid sequence of SEQ ID NO: 125, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 126 (a variant thereof or a fragment thereof).

[0057] In some embodiments, the engineered metabolic pathway to convert acetyl-coenzyme A and acetate to acetone comprises an acetoacetate decarboxylase. As used herein, the terms “acetoacetate decarboxylase”, and “ADC” are intended to include the enzymes capable of converting acetoacetate to acetone and carbon dioxide. Acetoacetate decarboxylases include enzymes that correspond to Enzyme Commission Number 4.1.1.4. The acetoacetate decarboxylase can be native or heterologous to the recombinant yeast host cell. The recombinant yeast host cell can include a native acetoacetate decarboxylase and optionally in combination a heterologous acetoacetate decarboxylase. In some embodiments, acetoacetate decarboxylase is of prokaryotic or eukaryotic origin. In other embodiments, the acetoacetate decarboxylase can be encoded by an adc gene (e.g., ADC). In some embodiments, the acetoacetate decarboxylase is derived from Paenibacillus sp., and in further embodiments from Paenibacillus polymyxa. In such embodiments, the acetoacetate decarboxylase can include a polypeptide having the amino acid sequence of SEQ ID NO: 24, be a variant of the amino acid sequence of SEQ ID NO:24 having ADC activity or be a fragment of the amino acid sequence of SEQ ID NO: 24 having ADC activity. In such embodiment, the heterologous nucleic acid molecule encoding this polypeptide can comprise the nucleic acid sequence of SEQ ID NO: 23, or a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 24 (a variant thereof or a fragment thereof). In some embodiments, the acetoacetate decarboxylase is derived from Clostridium sp., and in further embodiments from Clostridium acetobutylicum. In such embodiments, the acetoacetate decarboxylase can include a polypeptide having the amino acid sequence of SEQ ID NO: 98, be a variant of the amino acid sequence of SEQ ID NO: 98 having ADC activity or be a fragment of the amino acid sequence of SEQ ID NO:98 having ADC activity. In such embodiment, the heterologous nucleic acid molecule encoding this polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 98 (a variant thereof or a fragment thereof). In some embodiments, the acetoacetate decarboxylase is derived from Clostridium beijerinckii. In such embodiments, the acetoacetate decarboxylase can include a polypeptide having the amino acid sequence of SEQ ID NO: 99, be a variant of the amino acid sequence of SEQ ID NO: 99 having ADC activity or be a fragment of the amino acid sequence of SEQ ID NO: 99 having ADC activity. In such embodiment, the heterologous nucleic acid molecule encoding this polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO:99 (a variant thereof or a fragment thereof). In some embodiments, the acetoacetate decarboxylase is derived from Bacillus sp., and in further embodiments from Bacillus amyloliquefaciens. In such embodiments, the acetoacetate decarboxylase can include a polypeptide having the amino acid sequence of SEQ ID NO: 100, be a variant of the amino acid sequence of SEQ ID NO: 100 having ADC activity or be a fragment of the amino acid sequence of SEQ ID NO: 100 having ADC activity. In such embodiment, the heterologous nucleic acid molecule encoding this polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO:100 (a variant thereof or a fragment thereof). In some embodiments, the acetoacetate decarboxylase is derived from Rhizobium sp., and in further embodiments from Rhizobium leguminosarum bv. trifolii. In such embodiments, the acetoacetate decarboxylase can include a polypeptide having the amino acid sequence of SEQ ID NO: 101 , be a variant of the amino acid sequence of SEQ ID NO: 101 having ADC activity or be a fragment of the amino acid sequence of SEQ ID NO: 101 having ADCactivity. In such embodiment, the heterologous nucleic acid molecule encoding this polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 101 (a variant thereof or a fragment thereof). In some embodiments, the acetoacetate decarboxylase is derived from Bradyrhizobium sp., and in further embodiments from Bradyrhizobium japonicum. In such embodiments, the acetoacetate decarboxylase can include a polypeptide having the amino acid sequence of SEQ ID NO: 102, be a variant of the amino acid sequence of SEQ ID NO: 102 having ADC activity or be a fragment of the amino acid sequence of SEQ ID NO:102 having ADC activity. In such embodiment, the heterologous nucleic acid molecule encoding this polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 102 (a variant thereof or a fragment thereof). In some embodiments, the acetoacetate decarboxylase is derived from Tetrahymena sp., and in further embodiments from Tetrahymena thermophila. In such embodiments, the acetoacetate decarboxylase can include a polypeptide having the amino acid sequence of SEQ ID NO: 103, be a variant of the amino acid sequence of SEQ ID NO:103 having ADC activity or be a fragment of the amino acid sequence of SEQ ID NO:103 having ADC activity. In such embodiment, the heterologous nucleic acid molecule encoding this polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 103 (a variant thereof or a fragment thereof). In some embodiments, the acetoacetate decarboxylase is derived from Aspergillus sp., and in further embodiments from Aspergillus niger. In such embodiments, the acetoacetate decarboxylase can include a polypeptide having the amino acid sequence of SEQ ID NO: 104, be a variant of the amino acid sequence of SEQ ID NO:104 having ADC activity or be a fragment of the amino acid sequence of SEQ ID NO: 104 having ADC activity. In such embodiment, the heterologous nucleic acid molecule encoding this polypeptide can comprise a degenerate nucleic acid sequence encoding the amino acid sequence of SEQ ID NO: 104 (a variant thereof or a fragment thereof). Additional sources of ADC that can be included in the recombinant yeast host cell include, without limitation, Chromobacterium violaceum (Uniprot Q7NSA6, for example), Pseudomonas putida, and Ruminiclostridium cellulolyticum.

[0058] In some embodiments, the engineered metabolic pathway to convert acetyl-coenzyme A and acetate to acetone further comprises one or more native enzyme that function in a pathway to convert acetone to isopropanol. The one or more native enzyme comprises one or more native alcohol dehydrogenase. As used herein,the terms “alcohol dehydrogenase”, and “ADIT are intended to include the enzymes capable of converting an alcohol into an aldehyde (primary alcohol dehydrogenase) or a ketone (secondary alcohol dehydrogenase). Alcohol dehydrogenases include enzymes that correspond to Enzyme Commission Number 1.1.1.1. In some embodiments, the one or more native enzyme that function in a pathway to convert acetone to isopropanol comprises one or more native secondary alcohol dehydrogenase.Process of using the recombinant yeast host cell

[0059] The present disclosure provides a process for increasing acetyl-coA production (e.g., the intracellular production) in the recombinant yeast host cell when compared to a control yeast host cell lacking at least one of: (i) at least two copies of a heterologous nucleic acid molecule encoding the phosphoketolase; (ii) a native and / or heterologous enzyme that functions in an engineered non-oxidative pentose phosphate pathway, wherein the native and / or heterologous enzyme is activated, upregulated, or overexpressed; and / or (iii) a native and / or heterologous protein that functions in an engineered metabolic pathway to convert pantothenate into acetylcoenzyme A (e.g., at least one of: FEN2 or CAB1 ). It may not be possible to directly determine the increase in acetyl-coA production in the recombinant yeast host cell, however it can be inferred that an increase in acetyl-coA did occur in the recombinant yeast host cell by directly measuring one or more products derived from acetyl-coA (like acetone and / or isopropanol for example).

[0060] Broadly, the process of the present disclosure comprises contacting the recombinant yeast host cell with the biomass under conditions to allow the conversion of at least in part of the biomass into acetyl-coA (e.g., fermenting step). In some embodiments, the contacting step occurs under conditions to allow the conversion of at least in part of the biomass into acetone. Alternatively, or in combination, the contacting step occurs under conditions to allow the conversion of at least in part of the biomass into isopropanol. The process can optionally include a step of isolating the acetone and / or the isopropanol from the fermented biomass (using distillation for example).

[0061] In some embodiments, the process of the present disclosure comprises a plurality of fermentations in which the biomass is recycled between two rounds of fermentations. In some embodiments, the recombinant yeast host cells are only exogenously added in the initial fermentation cycle and are then recycled in furtherfermentation cycles. Each fermentation cycle of the process includes contacting a fermentation medium (comprising a fermentable carbohydrate) with a fermenting population under conditions so as to allow the conversion of the fermentable carbohydrate in a fermentation product (e.g., fermentation). At the end of the fermentation, the fermenting population present in the fermented fermentation medium is substantially isolated from the fermented fermentation medium and use to initiate another fermentation cycle. It is understood that, in such embodiments, the initial fermenting population consists essentially in the recombinant yeast host cells of the present disclosure and that, during the plurality of the fermentation cycles, the recycled fermenting population can include some contaminating wild (non-genetically modified) yeasts. The plurality of fermentation cycles can include at least one continuous fermentation. The plurality of fermentation cycles can only include continuous fermentations. The plurality of fermentation cycles can include at least one batch fermentation. The plurality of fermentation cycles can only include batch fermentations. The processes of the present disclosure can include an initial fermentation cycle at least one, two, three, four, five, six, seven, eight, nine, 10, 15, 20, 25, 30, 35, 40,45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200 or more further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 39 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 49 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 59 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 69 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 79 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 89 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 99 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 109 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 119 further fermentation cycles. In specific embodiments, the processes of the present disclosureinclude an initial fermentation cycle at least 129 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 139 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 149 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 159 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 169 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 179 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 189 further fermentation cycles. In specific embodiments, the processes of the present disclosure include an initial fermentation cycle at least 199 further fermentation cycles.

[0062] The biomass that can be fermented with the recombinant yeast host cells described herein includes any type of biomass known in the art and described herein. For example, the biomass can include, but is not limited to, starch, sugar and lignocellulosic materials comprising lignocellulosic fibers. Starch materials can include, but are not limited to, mashes such as com, wheat, rye, barley, rice, or milo. The starch present in the biomass can be totally or in part in a raw form or in a gelatinized form. When the biomass comprises or is derived from com, it can include a com mash. Sugar materials can include, but are not limited to, sugar beets, artichoke tubers, sweet sorghum, molasses or cane. The terms “lignocellulosic material”, “lignocellulosic substrate” and “cellulosic biomass” mean any type of biomass comprising cellulose, hemicellulose, lignin, or combinations thereof, such as but not limited to woody biomass, forage grasses, herbaceous energy crops, non-woody-plant biomass, agricultural wastes and / or agricultural residues, forestry residues and / or forestry wastes, paper-production sludge and / or waste paper sludge, waste -water-treatment sludge, municipal solid waste, com fiber from wet and dry mill com ethanol plants and sugar-processing residues. The terms “hemicellulosics”, “hemicellulosic portions” and “hemicellulosic fractions” mean the non-lignin, non-cellulose elements of lignocellulosic material, such as but not limited to hemicellulose (i.e., comprising mannan, glucomannan and galactoglucomannan), pectins (e.g., homogalacturonans, rhamnogalacturonan I and II, and xylogalacturonan) and proteoglycans (e.g., arabinogalactan-protein). In some embodiments, the biomass can include and / or besupplemented with citric acid (especially when acetic acid or acetate is the first metabolic product).

[0063] In a non-limiting example, the lignocellulosic material can include, but is not limited to, woody biomass, such as recycled wood pulp fiber, sawdust, hardwood, softwood, and combinations thereof; grasses, such as switch grass, cord grass, rye grass, reed canary grass, miscanthus, or a combination thereof; sugar-processing residues, such as but not limited to sugar cane bagasse; sugar cane must; agricultural wastes, such as but not limited to rice straw, rice hulls, barley straw, corn cobs, cereal straw, wheat straw, canola straw, oat straw, oat hulls, and corn fiber; stover, such as but not limited to soybean stover, corn stover; succulents, such as but not limited to, agave; and forestry wastes, such as but not limited to, recycled wood pulp fiber, sawdust, hardwood (e.g., poplar, oak, maple, birch, willow), softwood, or any combination thereof. Lignocellulosic material may comprise one species of fiber; alternatively, lignocellulosic material may comprise a mixture of fibers that originate from different lignocellulosic materials. Other lignocellulosic materials are agricultural wastes, such as cereal straws, including wheat straw, barley straw, canola straw and oat straw; com fiber; stovers, such as corn stover and soybean stover; grasses, such as switch grass, reed canary grass, cord grass, and miscanthus; or combinations thereof.

[0064] Substrates for cellulose activity assays can be divided into two categories, soluble and insoluble, based on their solubility in water. Soluble substrates include cellodextrins or derivatives, carboxymethyl cellulose (CMC), or hydroxyethyl cellulose (HEC). Insoluble substrates include crystalline cellulose, microcrystalline cellulose (Avicel), amorphous cellulose, such as phosphoric acid swollen cellulose (PASC), dyed or fluorescent cellulose, and pretreated lignocellulosic biomass. These substrates are generally highly ordered cellulosic material and thus only sparingly soluble.

[0065] It will be appreciated that suitable lignocellulosic material may be any feedstock that contains soluble and / or insoluble cellulose, where the insoluble cellulose may be in a crystalline or non-crystalline form. In various embodiments, the lignocellulosic biomass comprises, for example, wood, corn, corn stover, sawdust, bark, molasses, sugarcane, leaves, agricultural and forestry residues, grasses such as switchgrass, ruminant digestion products, municipal wastes, paper mill effluent, newspaper, cardboard or combinations thereof.

[0066] Paper sludge is also a viable feedstock for lactate or acetate production. Paper sludge is solid residue arising from pulping and paper-making and is typically removed from process wastewater in a primary clarifier. The cost of disposing of wet sludge is a significant incentive to convert the material for other uses, such as conversion to ethanol. Processes provided by the present invention are widely applicable. Moreover, the saccharification and / or fermentation products may be used to produce ethanol or higher value-added chemicals, such as organic acids, aromatics, esters, acetone and polymer intermediates.

[0067] The fermentation step of the process can be performed at temperatures of at least about 25°C, about 28°C, about 30°C, about 31 °C, about 32°C, about 33°C, about 34°C, about 35°C, about 36°C, about 37°C, about 38°C, about 39°C, about 40°C, about 41 °C, about 42°C, or about 50°C. In some embodiments, the process can be conducted at temperatures above about 30°C, about 31 °C, about 32°C, about 33°C, about 34°C, about 35°C, about 36°C, about 37°C, about 38°C, about 39°C, about 40°C, about 41 °C, about 42°C, or about 50°C.

[0068] In some embodiments, prior to fermentation, a step of liquefying starch can be included in the process. In such embodiment, the liquefied starch is then submitted to a following fermentation step. The liquefaction of starch can be performed at a temperature of between about 70°C-105°C to allow for proper gelatinization and hydrolysis of the starch. In an embodiment, the liquefaction occurs at a temperature of at least about 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C or 105°C. Alternatively or in combination, the liquefaction occurs at a temperate of no more than about 105°C, 100°C, 95°C, 90°C, 85°C, 80°C, 75°C or 70°C. In yet another embodiment, the liquefaction occurs at a temperature between about 80°C and 85°C (which can include a thermal treatment spike at 105°C).

[0069] During fermentation, the pH of the biomass can be equal to or below 5.5, 5.4, 5.3, 5.2, 5.1 , 5.0, 4.9, 4.8, 4.7., 4.6, 4.5, 4.4, 4.3, 4.2, 4.1 , 4.0 or lower. In an embodiment, the pH of the fermentation medium (during fermentation) is between 4.0 and 5.5.

[0070] In the process described herein, it is possible to add an exogenous source (e.g., to dose) of an enzyme to facilitate saccharification or improve fermentation yield. As such, the process can comprise including one or more dose of one or more exogenous enzyme during the liquefaction / saccharification and / or the fermentation step. The exogenous enzyme can be provided in a purified form or incombination with other enzymes (e.g., a cocktail). In the context of the present disclosure, the term “exogenous” refers to a characteristic of the enzyme, namely that it has not been produced during the saccharification or the fermentation step, but that it was produced prior to the saccharification or the fermentation step. The exogenous enzyme that can be used during the saccharification / fermentation process can include, without limitation, an alpha-amylase, a glucoamylase, a protease, a phytase, a pullulanase, a cellulase, a xylanase, a trehalase, or any combination thereof.

[0071] In the process described herein, it is possible to add a nitrogen source (usually urea or ammonia) to facilitate liquefaction / saccharification or improve fermentation yield. As such, the process can comprise including one or more amount of the nitrogen source prior to or during the saccharification and / or the fermentation step.

[0072] The invention now being generally described, it will be more readily understood by reference to the following examples, which are included merely for purposes of illustration of certain aspects and embodiments of the present invention and are not intended to limit the invention.EXAMPLE I - Up-Regulation of Pentose Phosphate Pathway Enzymes to Increase Acetyl -Coenzyme A Production and Derived Compounds

[0073] Table 1 provides a description of the genetic modifications introduced in Saccharomyces cerevisiae strains / isolates of Example I.Table 1. Genetic modifications of the strains / isolates characterized in Example I. Strains are identified with a M* isolates are identified with a T*. All the strains and isolates were derived from a non-genetically modified Saccharomyces cerevisiae strain (e.g., M2390).

[0074] Description of the heterologous proteins / genes presented in Table 1. Heterologous ERG10 has the amino acid sequence of SEQ ID NO: 10 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 9. Heterologous CTFA has the amino acid sequence of SEQ ID NO: 20 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 19. Heterologous CTFB has the amino acid sequence of SEQ ID NO: 22 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 21. Heterologous ADC has the amino acid sequence of SEQ ID NO: 24 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 23. Heterologous PHK has the amino acid sequence of SEQ ID NO: 4 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 3. Heterologous ACK has the amino acid sequence of SEQ ID NO: 8 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 7. Heterologous TAL1 has the amino acid sequence of SEQ ID NO: 14 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 13. Heterologous TKL1 has the amino acid sequence of SEQ ID NO: 12 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 11. Heterologous RPE1 has the amino acid sequence of SEQ ID NO: 16 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 15. Heterologous RKI1 has the amino acid sequence of SEQ ID NO: 18 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 17.

[0075] Lab-scale fermentation conditions. An overnight culture in a YPD40 medium of the yeast strains / isolates was inoculated (1 % v / v) in a YPD120 / VD medium (comprising 10 g / L of yeast extract, 20 g / L of peptone, 120 g / L of dextrose, 1X Verduyn trace elements / vitamins solution, pH adjusted to 5.5). The fermentations were conducted in a fermentation volume of 30 mL in 60 mL serum bottles. The fermentations were conducted at a temperature of 32°C as well as under agitation (150 rpm). The fermentations lasted about 67 hours. The amount of metabolites present in the fermented medium were determined by HPLC.

[0076] It was first determined if the upregulation in the expression of the non- oxidative pentose phosphate pathway (PPP) in conjunction with the heterologous expression of a phosphoketolase (PHK) would facilitate the conversion of fructose-6- phosphate into acetyl-phosphate. In yeasts, the non-oxidative PPP consists of four enzymes, transketolase (TKL1 ), transaldolase (TAL1 ), ribulose-5-P 3-epimerase(RPE1 ), and ribose-5-P isomerase (RKI1 ). The genes involved in the non-oxidative pentose phosphate pathway were up regulated within three acetone production strains: M28256 (one copy of PHK), M28258 (one copy of PHK and one copy of ACK), and M28452 (two copies of PHK and one copy of ACK). The resulting strains were screened for acetate and acetone production in lab scale fermentations as indicated above. When compared to the strains lacking the heterologous genes involved in the non-oxidative PPP, the strains having the heterologous genes involved in the non- oxidative PPP did not significantly increase their production of acetone (Figure 2). However, isolates T11212, T11213, and T11214, which comprises two copies of the heterologous gene encoding PHK, produced an acetate titer increased by two-fold, suggesting that flux towards acetyl-phosphate was enhanced. The results shown in Figure 2 indicate that the combination of the non-oxidative PPP enzymes with PHK is important for increasing flux from fructose-6-phosphate towards acetyl-phosphate, and eventually towards acetyl-coA and downstream products.EXAMPLE II - Up-Regulation of Coenzyme A Synthesis to increase Acetyl- Coenzyme A Production and Derived Compounds

[0077] Table 2 provides a description of the genetic modifications introduced in Saccharomyces cerevisiae strains of Example II.Table 2. Genetic modifications of the strains characterized in Example II. All the strains were derived from a non-genetically modified Saccharomyces cerevisiae strain (e.g., M2390).

[0078] Description of the heterologous proteins / genes presented in Table 2. Heterologous CAB1 has the amino acid sequence of SEQ ID NO: 28 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 27.

[0079] Lab-scale fermentation conditions. An overnight culture in a YPD40 medium of the yeast strains / isolates was inoculated (1 % v / v) in a YPD120 / VD medium (comprising 10 g / L of yeast extract, 20 g / L of peptone, 120 g / L of dextrose, 1X Verduyn trace elements / vitamins solution, pH adjusted to 5.5). The fermentations were conducted in a fermentation volume of 30 mL in 60 mL serum bottles. The fermentations were conducted at a temperature of 32°C as well as under agitation (150 rpm). The fermentations lasted about 66 hours. The amount of metabolites present in the fermented medium were determined by HPLC.

[0080] It was then determined if the overexpression of the pantothenate kinase CAB1 could have an impact on the amount of acetyl-coenzyme A produced. The generation of acetyl-coenzyme A requires adequate levels of cytosolic coenzyme A and the pantothenate kinase encoded by CAB1 is responsible for the first step in the conversion of pantothenate to coenzyme A (Figure 3). Consequently, a CAB1 overexpression cassette was introduced into strains M28707, M28701 , and M28703 which vary in their copy numbers of PHK and ACK (see Table 2 as well as the legend in Figure 4). Increasing CAB1 expression led to increase acetone production in all of the strain backgrounds, resulting in a 30-43% increase in titer (Figure 4). In addition to the increased acetone titers, overexpression of CAB1 also significantly reduced the amount of residual acetate produced by the strains confirming that conversion of acetate to acetyl-coA was improved (Figure 4). The data presented in Figure 4 suggested that increasing the availability of the coenzyme A co-factor via overexpression of CAB1 lead to improved flux of glucose to acetyl-coenzyme A and eventually to acetone via the PHK-dependent pathway.EXAMPLE III - Overexpression of CAB1 and FEN2 in Corn Mash Fermentation

[0081] Table 3 provides a description of the genetic modifications introduced in Saccharomyces cerevisiae strains of Example III.Table 3. Genetic modifications of the strains and isolates characterized in Example III. Strains are identified with a M* isolates are identified with a T*. All the strains and isolates were derived from a non-genetically modified Saccharomyces cerevisiae strain (e.g., M2390).

[0082] Description of the heterologous proteins / genes presented in Table 3. Heterologous ERG10 has the amino acid sequence of SEQ ID NO: 10 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 9. Heterologous CTFA has the amino acid sequence of SEQ ID NO: 20 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 19. Heterologous CTFB has the amino acid sequence of SEQ ID NO: 22 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 21. Heterologous ADC has the amino acid sequence of SEQ ID NO: 24 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 23. Heterologous PHK has the amino acid sequence of SEQ ID NO: 4 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 3. Heterologous ACK has the amino acid sequence of SEQ ID NO: 8 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 7. Heterologous TAL1 has the amino acid sequence of SEQ ID NO: 14 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 13. Heterologous TKL1 has the amino acid sequence of SEQ ID NO: 12 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 11. Heterologous RPE1 has the amino acid sequence of SEQ ID NO: 16 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 15.Heterologous RKI1 has the amino acid sequence of SEQ ID NO: 18 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 17. Heterologous PTA has the amino acid sequence of SEQ ID NO: 6 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 5. Heterologous FEN2 has the amino acid sequence of SEQ ID NO: 26 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 25. Heterologous CAB1 has the amino acid sequence of SEQ ID NO: 28 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 27. Heterologous CAB1W331Rhas the amino acid sequence of SEQ ID NO: 108 and is encoded by a heterologous nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 107.

[0083] Lab-scale corn mash fermentation conditions. An overnight culture in a YPD40 medium of the yeast strains / isolates was inoculated (0.06 g / L) in a corn mash medium (comprising 0.45 Agu / g of total solids of Alcolase 146, 130 ppm of urea as well as antibiotics). The fermentations were conducted in a fermentation volume of 30 mL in 60 mL serum bottles. The fermentations were conducted at a temperature of 33°C for the first 24 hours and at a temperature of 31 °C thereafter. The fermentations lasted about 70 hours. The amount of metabolites present in the fermented medium were determined by HPLC.

[0084] It was then determined if FEN2, the native pantothenate transporter in S. cerevisiae, might further improve the supply of coenzyme A in addition to the heterologous expression of CAB1. Strain M29069 was used as a control strain and compared to isolates T12127, T12129, and T12128. Upregulation of FEN2 alone resulted in a 23% increase in acetone (see results obtained with isolate T12127 in Figure 5), upregulation of CAB1 alone increased acetone titer by 31 % (see results obtained with isolate T12129 in Figure 5), and the FEN2 / CAB1 combination by 45% (see results obtained with isolate T12128 in Figure 5). The data presented in Figure 5 further supported that increasing the supply of the coenzyme A co-factor can lead to improved production of acetyl-coenzyme A and downstream product acetone via the PHK dependent pathway.

[0085] Lab-scale YPD fermentations conditions. An overnight culture in a YPD40 medium of the yeast strains / isolates was inoculated (5 mL) in a YPD120 medium. The fermentations were conducted in a fermentation volume of 30 mL in 60 mL serum bottles. The fermentations were conducted at a temperature of 32°C for about 67hours. The amount of metabolites present in the fermented medium were determined by HPLC.

[0086] It was further determined if the mutant version of CAB1 (e.g., CAB1W331 R) could further increase acetone production. To do so, strains M2390, M30291 as well as isolate T12267 were used to conduct a fermentation in a YPD120 medium. As shown in Table 4 below, the production of acetone was further increased by isolate T12267 (expressing CAB1W331R) when compared to strain M30291 (expressing wild-type CAB1 ). The difference in acetone production between isolate T12267 and strain M30291 is statistically significant.Table 4. Acetic acid and acetone yield obtained using strains M2390, M30291 as well as isolate T12267 after fermentation in a YPD120 medium. Results were obtained for n=2 (for strains M2390 and M30291 ) or of n=6 (for isolate T12267). Results are provided as g / L ± SD for each of the metabolites.EXAMPLE IV - Increased Phosphoketolase Activity to increase Acetyl -coA Production and Derived Compounds

[0087] Table 5 provides a description of the genetic modifications introduced in Saccharomyces cerevisiae strains of Example IV.Table 5. Genetic modifications of the strains and isolates characterized in Example IV. Strains are identified with a M* isolates are identified with a T*. All the strains and isolates were derived from a non-genetically modified Saccharomyces cerevisiae strain (e.g., M2390).

[0088] Description of the heterologous proteins / genes presented in Table 5. Heterologous ERG10 has the amino acid sequence of SEQ ID NO: 10 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 9. Heterologous CTFA has the amino acid sequence of SEQ ID NO: 20 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 19. Heterologous CTFB has the amino acid sequence of SEQ ID NO: 22 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 21. Heterologous ADC has the amino acid sequence of SEQ ID NO: 24 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 23. Heterologous PHK has the amino acid sequence of SEQ ID NO: 4 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 3. Heterologous TAL1 has the amino acid sequence of SEQ ID NO: 14 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 13.Heterologous TKL1 has the amino acid sequence of SEQ ID NO: 12 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 11. Heterologous RPE1 has the amino acid sequence of SEQ ID NO: 16 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 15. Heterologous RKI1 has the amino acid sequence of SEQ ID NO: 18 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 17. Heterologous ACS2 has the amino acid sequence of SEQ ID NO: 2 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 1 .

[0089] Lab-scale corn mash fermentation conditions. An overnight culture in a YPD40 medium of the yeast strains / isolates was inoculated (0.06 g / L) in a corn mash medium (comprising 0.45 Agu / g of total solids of Alcolase 146, 130 ppm of urea as well as antibiotics). The fermentations were conducted in a fermentation volume of 30 mL in 60 mL serum bottles. The fermentations were conducted at a temperature of 33°C for the first 24 hours and at a temperature of 31 °C thereafter. The fermentations lasted about 70 hours. The amount of metabolites present in the fermented medium were determined by HPLC.

[0090] It was determined how the expression level of heterologous PHK might impact the production of acetyl-coenzyme A, three isolates (T12104, T12105, and T12106) were constructed in the background strain of M29071 , which itself already contained two copies of heterologous PHK. As shown in Figure 5, increasing the copy number of heterologous PHK resulted in increased acetone and acetate production. This result indicated that PHK activity is important in the production of acetyl-coenzyme A and downstream products.EXAMPLE V - Combination of Pathway Modifications for Enhanced Production of Acetyl-coA and Derived Products

[0091] Table 6 provides a description of the genetic modifications introduced in Saccharomyces cerevisiae strains characterized of Example V.Table 6. Genetic modifications of the strains and isolates characterized in Example V. Strains are identified with a M* isolates are identified with a T*. All the strains and isolates were derived from a non-genetically modified Saccharomyces cerevisiae strain (e.g., M2390).

[0092] Description of the heterologous proteins / genes presented in Table 6. Heterologous PHK has the amino acid sequence of SEQ ID NO: 4 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 3. Heterologous ACK has the amino acid sequence of SEQ ID NO: 8 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 7. Heterologous TAL1 has the amino acid sequence of SEQ ID NO: 14 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 13. Heterologous TKL1 has the amino acid sequence of SEQ ID NO: 12 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 11. Heterologous RPE1 has the amino acid sequence of SEQ ID NO: 16 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 15. Heterologous RKI1 has the amino acid sequence of SEQ ID NO: 18 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 17. Heterologous FEN2 has the amino acid sequence of SEQ ID NO: 26 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 25. Heterologous CAB1 has the amino acid sequence of SEQ ID NO: 28 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 27. Heterologous ACS2 has the amino acid sequence of SEQ ID NO: 2 and is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 1 .

[0093] Lab-scale corn mash fermentation conditions. An overnight culture in a YPD40 medium of the yeast strains / isolates was inoculated (0.06 g / L) in a corn mash medium (comprising 0.45 Agu / g of total solids of Alcolase 146, 236 ppm of urea as well as antibiotics). The fermentations were conducted in a fermentation volume of 30 mL in 60 mL serum bottles. The fermentations were conducted at a temperature of 33°C for the first 24 hours and at a temperature of 31 °C thereafter. The fermentations lasted about 66 hours. The amount of metabolites present in the fermented medium were determined by HPLC.

[0094] To test the impact of bringing together several modifications for the production of acetyl-coA and derived products, several strains / isolates were constructed as shown above in Table 6. The results in Figure 7 show that the heterologous expression of ACS2 along with PHK (in strain M30292) provide a significant increase in acetone and isopropanol production and a reduction in acetate as compared with the parental strain M29069. The heterologous expression of FEN2 and CAB1 along with another copy of the heterologous non-oxidative PPP enzymes as well as another copy of a heterologous PHK (in isolates T12200-8, T12203-7, and T12199-7) led to a further substantial increase in acetone production (Figure 7). Further decreases in acetate were also observed (Figure 7). Together these results showed that the functioning of the PHK dependent pathway to produce acetyl-co enzyme A and derived products can be substantially enhanced by increasing heterologous PHK activity, activity of heterologous enzymes of the oxidative pentose phosphate pathway, and heterologous enzymes associated with the supply of the coenzyme A co-factor.

Claims

WHAT IS CLAIMED IS :

1. A recombinant yeast host cell having one or more of native and / or heterologous enzymes that function in an engineered metabolic pathway to convert fructose-6- phosphate to acetyl-coenzyme A, wherein the plurality of native and / or heterologous enzymes is activated, upregulated, or overexpressed and comprises: a phosphoketolase; and optionally an acetate kinase, and / or a phosphotransacetylase; and wherein the recombinant yeast host cell comprises at least one of:(i) at least two copies of a heterologous nucleic acid molecule encoding the phosphoketolase;(ii) a native and / or heterologous enzyme that functions in an engineered non- oxidative pentose phosphate pathway, wherein the native and / or heterologous enzyme is activated, upregulated, or overexpressed; and / or(iii) a native and / or heterologous protein that functions in an engineered metabolic pathway to convert pantothenate into acetyl-coenzyme A, wherein the native and / or heterologous protein is activated, upregulated or overexpressed and comprises at least one of: FEN2 or CAB1 .

2. The recombinant yeast host cell of claim 1 , further comprising one or more of native and / or heterologous enzymes that function in an engineered metabolic pathway to convert acetate into acetyl-coenzyme A, wherein the plurality of the native and / or heterologous enzymes comprises an activated, upregulated or overexpressed ACS2; and optionally a deleted native ALD6.

3. The recombinant yeast host cell of claim 1 or 2, further comprising a native and / or heterologous enzyme that functions in an engineered metabolic pathway to convert acetyl-coenzyme A and acetate to acetone, wherein the native and / or heterologous enzyme is activated, upregulated, or overexpressed and comprises at least one of: a thiolase, a coenzyme A transferase, or an acetoacetate decarboxylase.

4. The recombinant yeast host cell of claim 3, further comprising a native enzyme that functions in a pathway to convert acetone to isopropanol, wherein the native enzyme comprises an alcohol dehydrogenase.

5. The recombinant yeast host cell of claim 4, wherein the alcohol dehydrogenase is a secondary alcohol dehydrogenase.

6. The recombinant yeast host cell of any one of claims 1 to 5, wherein the phosphoketolase:has the ability to convert D-xylulose 5-phosphate into D-glyceraldehyde 3-phosphate and acetyl-phosphate; has the ability to convert D-fructose 6-phosphate into D-erythrose 4- phosphate; has the ability to convert D-sedoheptulose 7-phosphate into D-ribose 5- phosphate; has single- or multiple-specificity; is of prokaryotic or eukaryotic origin; is encoded by a phk1 gene or a phk2 gene; is derived from Bifidobacterium, Lactobacillus, Leuconostoc, Penicillium, Aspergillus, Oenococcus or Neurospora species; is derived from Bifidobacterium bifidum, Bifidobacterium brevi, Bifidobacterium gallicum, Bifidobacterium animalis, Bifidobacterium adolescentis, Lactobacillus pentosum, Lactobacillus acidophilus, Lactobacillus casei, Lactiplantibacillus plantarum, Penicillium chrysogenum, Aspergillus niger, Aspergillus nidulans, Aspergillus clavatus, Neurospora crassa, Leuconostoc mesenteroides or Oenococcus oenr, has the amino acid sequence of SEQ ID NO: 4, 37, 39, 41 , 43, 45, 47, 49, 51 , 53, 55, 57, 59, 61 , 63 or 65; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 3, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62 or 64.

7. The recombinant yeast host cell of any one of claims 1 to 6 comprising 4 copies or more of the heterologous nucleic acid molecule encoding the phosphoketolase.

8. The recombinant yeast host cell of any one of claims 1 to 7, wherein the native and / or heterologous enzyme that functions in the engineered non-oxidative pentose phosphate pathway comprises at least one of: a transaldolase, a transketolase, an epimerase, or an isomerase.

9. The recombinant yeast host cell of claim 8, wherein the transaldolase: has the ability to convert glyceraldehyde 3-phosphate into erythrose 4- phosphate;has the ability to convert sedoheptulose 7-phosphate into fructose 6- phosphate; is heterologous; is of prokaryotic or eukaryotic origin; is a TAL1 polypeptide; is encoded by a tall gene; is derived from Saccharomyces sp.; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 14; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO:

13. The recombinant yeast host cell of claim 8 or 9, wherein the transketolase: has the ability to convert ribose 5-phosphate into glyceraldehyde 3- phosphate; has the ability to convert fructose 6-phosphate into xylulose 5-phosphate; has the ability to convert xylulose 5-phoshate into sedoheptulose 7- phosphate; has the ability to convert glyceraldehyde 3-phosphate into erythrose 4- phosphate; is heterologous; is of prokaryotic or eukaryotic origin; is a TKL1 polypeptide; is encoded by a tkl1 gene; is derived from Saccharomyces sp.; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 12; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO:

11. The recombinant yeast host cell of any one of claims 8 to 10, wherein the epimerase: has the ability to convert ribulose 5-phosphate into xylulose 5-phosphate; has the ability to convert xylulose 5-phosphate into ribulose 5-phosphate; is heterologous;is of prokaryotic or eukaryotic origin; is a RPE1 polypeptide; is encoded by a rpe1 gene; is derived from Saccharomyces sp.; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 16; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 15.

12. The recombinant yeast host cell of any one of claims 8 to 11 , wherein the isomerase: has the ability to convert ribulose 5-phosphate into ribose 5-phosphate; has the ability to convert ribose 5-phosphate into ribulose 5-phosphate; is heterologous; is of prokaryotic or eukaryotic origin; is a RKI1 polypeptide; is encoded by a rki1 gene; is derived from Saccharomyces sp. ; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 18; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 17.

13. The recombinant yeast host cell of any one of claims 1 to 12, wherein the native and / or heterologous enzyme that functions in the engineered non-oxidative pentose phosphate pathway comprises at least two of the transaldolase, the transketolase, the epimerase, or the isomerase.

14. The recombinant yeast host cell of any one of claims 1 to 12, wherein the native and / or heterologous enzyme that functions in an engineered non-oxidative pentose phosphate pathway comprises at least three of the transaldolase, the transketolase, the epimerase, or the isomerase.

15. The recombinant yeast host cell of any one of claims 1 to 12, wherein the native and / or heterologous enzyme that functions in an engineered non-oxidative pentose phosphate pathway comprises the transaldolase, the transketolase, the epimerase, and the isomerase.

16. The recombinant yeast host cell of any one of claims 1 to 15, wherein the FEN2: is a plasma membrane proton-pantothenate symporter; is heterologous; is of prokaryotic or eukaryotic origin; is encoded by a fen2 gene; is derived from Saccharomyces sp. ; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 26; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 25.

17. The recombinant yeast host cell of any one of claims 1 to 16, wherein the CAB1 : has pantothenate kinase activity; is heterologous; is of prokaryotic or eukaryotic origin; is encoded by a cab1 gene; is derived from Saccharomyces sp. ; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 28; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 27.

18. The recombinant yeast host cell of claim 17, wherein the CAB1 is CAB1W331R.

19. The recombinant yeast host cell of any one of claims 1 to 18, wherein the native and / or heterologous protein that functions in the engineered metabolic pathway to convert pantothenate into acetyl-coenzyme A comprises FEN2.

20. The recombinant yeast host cell of any one of claims 1 to 18, wherein the native and / or heterologous protein that functions in the engineered metabolic pathway to convert pantothenate into acetyl-coenzyme A comprises CAB1 .21 . The recombinant yeast host cell of any one of claims 1 to 18, wherein the native and / or heterologous protein that functions in the engineered metabolic pathway to convert pantothenate into acetyl-coenzyme A comprises FEN2 and CAB1 .

22. The recombinant yeast host cell of any one of claims 2 to 21 , wherein the ACS2: has the ability to convert acetate into acetyl-coenzyme A;is heterologous; is from prokaryotic or eukaryotic origin; is encoded by an acs2 gene; is derived from Saccharomyces sp.; is derived from Saccharomyces cerevisiae', has the amino acid sequence of SEQ ID NO: 2; and / or is encoded by a nucleic acid molecule having the nucleic acid sequence of SEQ ID NO: 1.

23. The recombinant yeast host cell of any one of claims 3 to 22, wherein the thiolase:- is heterologous;- is of prokaryotic or eukaryotic origin;- is encoded by a thl gene, an erg10 gene or a phaA gene;- is derived from derived from Saccharomyces sp.;- is derived from Saccharomyces cerevisiae',- has the amino acid sequence of SEQ ID NO: 10; and / or- has the nucleic acid sequence of SEQ ID NO: 9.

24. The recombinant yeast host cell of any one of claims 3 to 23, wherein the coenzyme A transferase:- is heterologous;- is of prokaryotic or eukaryotic origin;- is encoded by a ctfA gene and a ctfB gene;- is encoded by a atoD and / or an atoA gene;- is derived from Alkaliphilus sp. ;- is derived from Alkaliphilus metalliredigens',- has the amino acid sequence of SEQ ID NO: 20 and / or 22; and / or- has the nucleic acid sequence SEQ ID NO: 19 and / or 21 .

25. The recombinant microorganism of any one of claims 3 to 24, wherein the acetoacetate decarboxylase:- is heterologous;- is of prokaryotic or eukaryotic origin;- is encoded by an adc gene;- is derived from Paenibacillus sp.;- is derived from Paenibacillus polymyxa',- has the amino acid sequence of SEQ ID NO: 24; and / or- has the nucleic acid sequence of SEQ ID NO: 23.

26. The recombinant yeast host cell of any one of claims 1 to 25, comprising at least two of: at least 2 copies of the heterologous nucleic acid molecule encoding the phosphoketolase, the native and / or heterologous enzyme that functions in the engineered non-oxidative pentose phosphate pathway, or the native and / or heterologous protein that functions in the engineered metabolic pathway to convert pantothenate into acetyl-coenzyme A.

27. The recombinant yeast host cell of any one of claims 1 to 26, comprising at least 2 copies of the heterologous nucleic acid molecule encoding the phosphoketolase, the native and / or heterologous enzyme that functions in the engineered non-oxidative pentose phosphate pathway, and the native and / or heterologous protein that functions in the engineered metabolic pathway to convert pantothenate into acetyl-coenzyme A.

28. The recombinant yeast host cell of any one of claims 1 to 27 being from the Saccharomyces genus.

29. The recombinant yeast host cell of claim 28 being from the Saccharomyces cerevisiae species.

30. The recombinant yeast host cell of claims 1 to 29 wherein the recombinant yeast host cell also produces ethanol.31 . A process for increasing the acetyl-coenzyme A production in a recombinant yeast host cell, the process comprising contacting a biomass with the recombinant yeast host cell defined in any one of claims claim 1 to 30 under conditions allowing the production of acetyl-coenzyme A, wherein the acetyl-coenzyme A production in the recombinant yeast host cell is increased when compared to a control yeast host cell lacking (i), (ii), and (iii) as defined in claim 1.

32. A process for converting a biomass into acetone, the process comprising contacting a biomass with the recombinant yeast host cell defined in any one of claims claim 3 to 30 under conditions allowing the conversion of at least part of the biomass into acetone.

33. A process for converting a biomass into isopropanol, the process comprising contacting a biomass with the recombinant yeast host cell defined in any one of claims4 to 30 under conditions allowing the conversion of at least part of the biomass into isopropanol.

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