Variant rhodospirillum microorganism with improved glucose assimilation capacity and uses thereof

Abstract

The present invention is directed to an improved microorganism of the genus Rhodospirillum for the production of biomass or other products such as amino acids, vitamins and proteins. In particular, a genetic variant microorganism of the genus Rhodospirillum is provided wherein the expression or activity of one or more genes or gene products of the xylitol assimilation gene cluster is modified as compared to the expression or activity of said one or more genes or gene products in a non-modified Rhodospirillum microorganism. Also the use of said microorganism and a method to produce biomass or other products using said microorganism are provided.

Description

[0001] VARIANT RHODOSPIRILLUM MICROORGANISM WITH IMPROVED GLUCOSE ASSIMILATION CAPACITY AND USES THEREOF FIELD

[0002] The invention is broadly in the field of microbiology, and in particular relates to microorganisms of the genus Rhodospirillum useful for the production of biomass or other products such as amino acids, vitamins and proteins. Also the use of said microorganisms and a method to produce biomass or other products using said microorganisms are provided.

[0003] BACKGROUND

[0004] Rhodospirillum (Rs) rubrum is a species of purple non-sulphurous bacterium (PNSB) known for its great metabolic versatility. Due to its capacity to grow on a large variety of carbon sources, PNSB-based processes are currently evolving rapidly and have a broad range of applications, including hydrogen, polyhydroxyalkanoates (PHA) and microbial protein production as well as the production of high-value components such as carotenoids or coenzyme Q10 (coQlO). Integrating these processes into a circular economy based on resource recovery offers outstanding prospects for environmental sustainability, enhancing the production of high-value products while minimizing climate and environmental impact.

[0005] PNSB microbial biomass is currently gaining increasing attention as a food alternative thanks to its excellent nutritional properties. This biomass is rich in high quality proteins and essential amino acids as well as in vitamins and carotenoids. Various carbon sources, including volatile fatty acids, alcohols, and carbohydrates, have been explored for being assimilated phototrophically by PNSBs. The use of co-products (starch residues, molasses, pomace, etc.) as well as food-grade effluents rich in carbohydrates are particularly favoured to produce microbial biomass because they are easily assimilated by several microorganism and they are abundant. Phototrophic metabolism, as utilized by PNSBs, presents a specific asset as in this case, carbohydrates would be used exclusively for biomass production and not for energy production, leading to a much higher carbon conversion factor. However, despite this asset, the development of PNSB-based processes at an industrial scale has not yet been implemented mainly because improvements are needed to reach techno-economically feasibility.

[0006] Studies have been carried out using sugar-rich products to promote the growth of PNSB. However, the range of sugars that can be assimilated and their metabolic pathways differ among PNSBs. Forexample, in Rhodobacter capsulatus and Rhodobacter sphaeroides, glucose is assimilated via the Entner-Doudoroff pathway, whereas in Rhodopseudomonas palustris, limited growth on glucose is observed, likely due to a lack of enzymes and transporters involved in glucose assimilation. On the other hand, Rs. rubrum is not capable of assimilating glucose. The reason for this inability to utilise glucose remains unclear. Given that Rs. rubrum is unable to assimilate glucose, process development is focusing on optimising growth and product formation by Rs. rubrum using other sources of carbon present in co-products, such as fructose. However, given that a large proportion of the co-products and waste water from the agri-food industries generally contains large quantities of glucose (as monosaccharide, disaccharide or polysaccharide), this represents a major limitation. Understanding how PNSBs photometabolize different carbon sources, and specifically carbohydrates, is thus fundamental to optimise bioprocesses for greater yield.

[0007] It is therefore an objective of the present invention to address the limitations of the current state of the art, in particular to address the limitations of the Rs. rubrum in glucose assimilation.

[0008] SUMMARY

[0009] The present invention is at least in part based on the inventors' insights that a variant microorganism of the genus Rhodospirillum, in particular a variant Rhodospirillum rubrum (Rs. rubrum) strain, is able to assimilate glucose whereas a non-variant, or unmodified or wild-type Rs. rubrum strain is unable to assimilate glucose. In particular, the inventors found that modifying the expression or activity of one or more genes or gene products of the xylitol assimilation gene cluster resulted in improved glucose assimilation in a Rs. rubrum strain as compared to the unmodified, non-variant, or wild-type strain. The inventors in particular found that upregulation of one or more of the proteins encoded by the xylitol assimilation gene cluster resulted in improved glucose assimilation in the microorganism. More specifically, genetically modifying one or more of the genes encoding for the proteins selected from Lacl transcriptional regulator, inner-membrane translocator, ABC transporter and / or xylulokinase resulted in an improved glucose assimilation capacity of the Rs. rubrum strain. Even further, a missense mutation in the gene encoding the Lacl transcriptional regulator, which is part of the xylitol assimilation gene cluster, significantly improved the glucose assimilation capacity of the variant or modified Rs. rubrum as compared to the unmodified, non-variant or wild-type Rs. rubrum. Also, a missense mutation in the gene encoding the inner-membrane translocator, which is also part of the xylitol assimilation gene cluster, improved the glucose assimilation capacity of the genetic variant or modified Rs. rubrum ascompared to the unmodified, non-variant or wild-type Rs. rubrum. The inventors further show that, in contrast to the wild-type Rs. rubrum strain, no accumulation of glucose occurs in a culture of the variant or modified Rs. rubrum microorganism when cultured in the presence of molassescontaining medium. As such, with the present invention, modified or variant Rhodospirillum microorganisms are provided that show an improved glucose assimilation capacity and that can be used for the production of useful products, such as biomass, extracts of said biomass, amino acids, vitamins, proteins, co-enzyme Q10, and / or carotenoids. Also methods for the production of these products comprising culturing the variant or modified microorganisms such as in a bioreactor are provided.

[0010] A first aspect of the invention provides a genetic variant microorganism of the genus Rhodospirillum, wherein the expression or activity of one or more genes or gene products of the xylitol assimilation gene cluster is modified as compared to the expression or activity of said one or more genes or gene products in a non-modified Rhodospirillum microorganism. The one or more genes of the xylitol assimilation gene cluster are selected from the Rru_A0247 gene, the Rru_A0248 gene, the Rru_A0249 gene and the Rru_0250 gene, which are the genes encoding for the proteins selected from the Lacl transcriptional regulator, the inner membrane translocator, the ABC transporter and xylulokinase. Typical for the genetic variant microorganism is that glucose assimilation is increased as compared to the non-variant or wild-type Rhodospirillum microorganism.

[0011] In some embodiments, a wild-type, non-modified or non-variant microorganism is modified by directed evolution, natural adaptation, or selection to obtain the genetic variant microorganism. In some embodiments, a wild-type, non-variant or -non-modified microorganism is modified by genetic engineering to obtain the genetic variant microorganism.

[0012] In some embodiments, the genetic variant microorganism comprises a genetic modification in one or more genes of the xylitol assimilation gene cluster, such as in one or more genes selected from the genes encoding for the proteins selected from the Lacl transcriptional regulator, the inner membrane translocator, the ABC transporter and / or xylulokinase, compared to a wild-type or non-variant microorganism. In certain embodiments, the genetic modification is a mutation, in particular a missense mutation.

[0013] In some embodiments, the genetic modification such as a mutation is in the Rru_A0247 gene encoding for the Lacl transcriptional regulator.In some embodiments, the genetic modification such as a mutation is in one or more genes selected from the Rru_A0248 gene encoding for the inner membrane translocator, the Rru_A0249 gene encoding for the ABC transporter and / or the Rru_A0250 gene encoding for xylulokinase.

[0014] In some further embodiments, the genetic modification such as a mutation is in the Rru_A0248 gene encoding for the inner membrane translocator.

[0015] In some embodiments, the expression or activity of the Rru_A0247 gene encoding for the Lacl transcriptional regulator or of the gene product Lacl transcriptional regulator is increased in the genetic variant microorganism as compared to the expression or activity of said gene or gene product in the non-variant or non-modified Rhodospirillum microorganism.

[0016] In some embodiments, the Lacl transcriptional regulator protein of the genetic variant microorganism has diminished ability to bind to the xylitol assimilation gene cluster operator as compared to the Lacl transcription regulator protein of the non-variant, wild-type or non-modified microorganism.

[0017] In some embodiments, the Lacl transcriptional regulator protein in the genetic variant microorganism comprises an amino acid substitution at position 43 as compared to the Lacl transcription regulator protein in the non-variant or non-modified Rhodospirillum microorganism wherein the Lacl transcription regulator protein of the non-modified Rhodospirillum microorganism comprises the amino acid sequence as presented in SEQ ID NO 2.

[0018] In some embodiments, the expression or activity of the Rru_A0248 gene encoding for the inner-membrane translocator protein or of the gene product inner-membrane translocator protein is increased in the genetic variant microorganism as compared to the expression or activity of said gene or gene product in the non-variant or non-modified Rhodospirillum microorganism.

[0019] In some embodiments, the inner-membrane translocator protein in the genetic variant microorganism comprises an amino acid substation at position 320 as compared to the inner-membrane translocator protein of the non-variant or non-modified Rhodospirillum microorganism wherein the inner-membrane translocator protein of the non-modified Rhodospirillum microorganism comprises the amino acid sequence as presented in SEQ ID NO 4.

[0020] In some embodiments, the genetic variant microorganism is a Rhodospirillum rubrum (Rs. rubrum) species.In some embodiments, the genetic variant microorganism is a Rs. rubrum strain as deposited under the Budapest Treaty at the Belgian Coordinated Collections of Micro-organisms (BCCM) on March 13, 2025 under Accession no. LMG P-34001 or a functional mutant thereof. In some further embodiments, the genetic variant microorganism is a Rs. rubrum strain as deposited under the Budapest Treaty at the Belgian Coordinated Collections of Micro-organisms (BCCM) on March 13, 2025 under Accession no. LMG P-34001.

[0021] Another aspect provides a microorganism that is a Rs. rubrum strain as deposited under the Budapest Treaty at the Belgian Coordinated Collections of Micro-organisms (BCCM) on March 13, 2025 under Accession no. LMG P-34001 or a functional mutant thereof. In some embodiments, a microorganism is provided that is a Rs. rubrum strain as deposited under the Budapest Treaty at the Belgian Coordinated Collections of Micro-organisms (BCCM) on March 13, 2025 under Accession no. LMG P-34001.

[0022] Further provided is a method of producing a genetic variant microorganism from a starting nonvariant or wild-type Rhodospirillum microorganism. The method comprises the steps of:

[0023] a) generating a population of genetic variant microorganisms from a starting non-variant or wild-type Rhodospirillum microorganism; and

[0024] b) selecting from said population a genetic variant microorganism which exhibits said increased glucose assimilation capacity as compared to the starting microorganism, wherein the genetic variant microorganism has modified expression or activity of one or more genes or gene products of the xylitol assimilation gene cluster as compared to the starting microorganism, and wherein the genes of the xylitol assimilation gene cluster are selected from the Rru_A0247 gene, the Rru_A0248 gene , the Rru_A0249 gene and the Rru_0250 gene, which are the genes encoding for the proteins selected from the Lacl transcriptional regulator, inner-membrane translocator, ABC transporter, and / or xylulokinase.

[0025] Another aspect of the invention provides a method to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation by introducing a genetic modification, in particular a mutation, more in particular a missense mutation, in one or more genes of the xylitol assimilation gene cluster. In some embodiments, the genes of the xylitol assimilation gene cluster are selected from the Rru_A0247 gene encoding for the Lacl transcriptional regulator, the Rru_A0248 gene encoding for the inner-membrane translocator, the Rru_A0249 gene encoding for the ABC transporter and the Rru_A0250 gene encoding for xylulokinase.In some embodiments, a method is provided to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation by introducing a genetic modification, in particular a mutation, more particular a missense mutation, in the Rru_A0247 gene that encodes for the Lacl transcriptional regulator.

[0026] In some embodiments, a method is provided to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation by introducing a genetic modification, in particular a mutation, more particular a missense mutation, in the Rru_A0248 gene that encodes for the inner-membrane translocator.

[0027] In some embodiments, a method is provided to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation by introducing a genetic modification, in particular a mutation, more particular a missense mutation, in the Rru_A0249 gene that encodes for the ABC transporter.

[0028] In some embodiments, a method is provided to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation by introducing a genetic modification, in particular a mutation, more particular a missense mutation, in the RrU_A0250 gene that encodes for the xylulokinase.

[0029] In some embodiments, a method is provided to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation by introducing a genetic modification, in particular a mutation, more particular a missense mutation, in the Rru_A0247 gene that encodes for the Lacl transcriptional regulator, and in one or more genes selected from the Rru_A0248 gene that encodes for the inner-membrane translocator, the Rru_0A249 gene that encodes for the ABC transporter and / or the Rru_A0250 gene that encodes for xylulokinase. In some further embodiments, a method is provided to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation by introducing a genetic modification, in particular a mutation, more particular a missense mutation, in the Rru_A0247 gene that encodes for the Lacl transcriptional regulator, in the Rru_A0248 gene that encodes for the inner-membrane translocator, the Rru_A0249 gene that encodes for the ABC transporter and the Rru_A0250 gene that encodes for xylulokinase.

[0030] In some embodiments of the methods disclosed herein, modification is performed via directed evolution, natural adaptation, or selection. In some embodiments, modification is done by genetic engineering.

[0031] Further provided is the useof the genetic variant microorganism disclosed herein for the production of amino acids, vitamins, proteins, biomass, and / or bioethanol.A further aspect provides a method for the production of one or more products, such as of amino acids, vitamins, proteins, biomass or extracts of biomass, co-enzyme Q10, carotenoids, and / or bioethanol, comprising culturing the genetic variant microorganism according to any of the aspects or embodiments of the invention in a substrate comprising carbohydrates and a culture medium under conditions that are suitable for growth of the genetic variant microorganism and for production of the one or more products, whereby said genetic variant microorganism produces the one or more products. Advantageously, the genetic variant microorganism may be cultured in a bioreactor which comprises the substrate and culture medium.

[0032] In some embodiments, the substrate in the above method for the production of one or more products comprises sucrose, fructose and / or glucose; in particular wherein the substrate comprises glucose.

[0033] Also provided is biomass obtainable by the above method for the production of biomass.

[0034] A further aspect provides a feed or nutritional product comprising biomass or extracts of said biomass, co-enzyme Q10, carotenoids, amino acids, vitamins, and / or proteins produced by the genetic variant microorganism according to any of the embodiments of the invention.

[0035] Another aspect provides a method for identifying, in a sample, the presence or prior use of a genetic variant microorganism as disclosed herein. Said method comprises:

[0036] - analysing a nucleic acid from the sample to detect:

[0037] i) at least one mutation in the Rru_A0247 gene encoding for the Lacl transcriptional regulator, optionally wherein the wild-type form of said gene comprises the nucleotide sequence as set forth in SEQ ID NO: 1;

[0038] ii) at least one mutation in the Rru_A0248 gene encoding for the inner-membrane translocator, optionally wherein the wild-type form of said gene comprises the nucleotide sequence as set forth in SEQ ID NO: 3; and

[0039] - identifying the presence or prior use of the genetic variant microorganism in the sample if said mutations are detected.

[0040] A further aspect provides a kit for identifying, in a sample, the presence or prior use of a genetic variant microorganism as disclosed herein. The kit comprises at least one reagent capable of detecting a mutation in the Rru_A0247 gene encoding for the Lacl transcriptional regulator, optionally wherein the wild-type form is said gene comprises the nucleotide sequence as set forthin SEQ ID NO: 1, and at least one reagent capable of detecting a mutation in the Rru_A0248 gene encoding for the inner-membrane translocator, optionally wherein the wild-type form of said gene comprises the nucleotide sequence as set forth in SEQ ID NO: 3.

[0041] In some embodiments, the sample is a food sample.

[0042] These and further aspects and preferred embodiments of the invention are described in the following sections and in the appended claims. The subject-matter of the appended claims is hereby specifically incorporated in this specification.

[0043] BRIEF DESCRIPTION OF DRAWINGS

[0044] The following description of the figures of specific embodiments of the invention is merely exemplary in nature and is not intended to limit the present teachings, their application or uses. Throughout the description and the accompanying figures, functionally similar features are referred to with like reference numerals incremented by 100.

[0045] Fig. 1 illustrates the monitoring of growth of the Rs. Rubrum wild-type (WT) strain cultivated in a glucose-containing medium. Xylitol was added in the medium after approximately 70h. Circle and square represent the evolution of glucose and xylitol concentration, respectively. N = 5. Results are represented as the mean ± SD.

[0046] Fig. 2 illustrates the monitoring of growth of the Rs. rubrum wild-type (WT) strain (A) ortheglucose-assimilated modified Rs. rubrum strain LMG P-34001 (MG strain) (B) in medium containing fructose (square), glucose (circle), or a mix of fructose and glucose (triangle) as carbon sources. N = 3. Results are represented as the mean ± SD.

[0047] Fig. 3 illustrates the monitoring of growth (inverted triangle) of the modified Rs. rubrum strain LMG P-34001 (MG strain) cultivated in a medium containing sucrose. Circle, square and triangle represent the evolution of glucose, fructose and sucrose concentration in the medium, respectively. N = 5. Results are represented as the mean ± SD.

[0048] Fig. 4 illustrates the growth of the Rs. rubrum wild-type (WT) strain (A) or the glucose-assimilated modified Rs. rubrum strain LMG P-34001 (MG strain) (B) in the presence of molasses. Growth isrepresented by the inversed triangle, whereas square, circle and triangle signs represent the fructose, glucose and sucrose concentration in the medium respectively.

[0049] DESCRIPTION OF EMBODIMENTS

[0050] As used herein, the singular forms "a", "an", and "the" include both singular and plural referents unless the context clearly dictates otherwise.

[0051] The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes", "containing", or "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. The terms also encompass "constituted of", "consists in", "consisting of", and "consists of", and also the terms "consisting essentially of", "consisting essentially in" and "consists essentially of", which enjoy well-established meanings in patent terminology.

[0052] The recitation of numerical ranges by endpoints includes all intervening values between the lower and upper endpoints, as well as the recited endpoints. Intervening values may be integers or, where applicable, fractions, i.e., more broadly any real numbers such as any rational numbers. This applies to numerical ranges irrespective of whether they are introduced by the expression "from... to..." or the expression "between... and..." or another expression. Any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, each sub-range between any stated value in a stated range and any other stated value in that stated range is also specifically disclosed. Each sub-range between any stated value in a stated range and either the lower endpoint or the upper endpoint of the stated range is also specifically disclosed. The stated value may be an isolated value or an endpoint of a range subsumed by or overlapping with the stated range. For example, for a stated range with lower endpoint LI and upper endpoint U1 (i.e., stated range Ll-Ul) and a stated sub-range nested within the stated range with lower endpoint L2 and upper endpoint U2 (i.e., stated sub-range L2-U2), also specifically disclosed are the subranges L1-L2, Ll-U2, L2-U1, and U2-U1.

[0053] The terms "about" or "approximately" as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, are meant to encompass variations of and from the specified value, such as variations of + / -10% or less, preferably + / -5% or less, more preferably + / -1% or less, and still more preferably + / -0.1% or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention. It is to be understoodthat the value to which the modifier "about" or "approximately" refers is itself also specifically, and preferably, disclosed.

[0054] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order, unless specified. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. Whereas the terms "one or more" or "at least one", such as one or more members or at least one member of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any >3, >4, >5, >6 or >7 etc. of said members, and up to all said members. In another example, "one or more" or "at least one" may refer to 1, 2, 3, 4, 5, 6, 7 or more.

[0055] As used herein, the term "and / or" when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a list is described as comprising group A, B, and / or C, the list can comprise A alone, B alone, C alone, A and B in combination, A and C in combination, B and C in combination, or A, B, and C in combination.

[0056] The discussion of the background to the invention herein is included to explain the context of the invention. This is not to be taken as an admission that any of the material referred to was published, known, or part of the common general knowledge in any country as of the priority date of any of the claims.

[0057] Throughout this disclosure, various publications, patents and published patent specifications are referenced by an identifying citation. All documents cited in the present specification are hereby incorporated by reference in their entirety. In particular, the teachings or sections of such documents herein specifically referred to are incorporated by reference.

[0058] Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the invention. When specific terms are defined in connection with a particular aspect of the invention or a particular embodiment of the invention, such connotation ormeaning is meant to apply throughout this specification, i.e., also in the context of other aspects or embodiments of the invention, unless otherwise defined.

[0059] In the following passages, different aspects or embodiments of the invention are defined in more detail. Each aspect or embodiment so defined may be combined with any other aspect(s) or embodiment(s) unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

[0060] Reference throughout this specification to "one embodiment", "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the appended claims, any of the claimed embodiments can be used in any combination.

[0061] Similarly, it should be appreciated that in the description of illustrative embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects.

[0062] In the present description of the invention, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration only of specific embodiments in which the invention may be practiced. Parenthesized or emboldened reference numerals affixed to respective elements merely exemplify the elements by way of example, with which it is not intended to limit the respective elements. Unless otherwise indicated, all figures and drawings in this document are not to scale and are chosen for the purpose of illustrating different embodiments of the invention. In particular the dimensions of the various components are depicted in illustrative terms only, and no relationship between the dimensions of the various components should be inferred from the drawings, unless so indicated.The present invention provides microorganisms of the genus Rhodospirilllum, such as Rs. rubrum, which are modified in such a manner that they can efficiently assimilate glucose.

[0063] Glucose is generally a preferred carbon source for microorganisms. It is the most commonly used sugar in fermentation media and in most bacteria it is efficiently converted to produce carbon molecules, such as fats, carbohydrates, proteins and nucleic acids. However, the range of sugars, including glucose, that can be assimilated and their metabolic pathways differ among different purple non-sulphurous bacteria such as bacteria of the Rhodospirillum genus. For example, the Rs. rubrum species is not capable of assimilating glucose and therefore process development so far has been focusing on optimising growth and product formation by Rs. rubrum using other sources of carbon than glucose present in co-products, such as fructose. Still, given that a large proportion of the co-products and wastewater from agri-food industries generally contains large quantities of glucose, this is a large limitation. The present application here discloses microorganisms of the genus Rhodospirillum that are able to assimilate glucose in a highly efficient manner.

[0064] As corroborated by the experimental section, which illustrates certain representative embodiments of the present invention, the inventors found that long-term exposure under phototrophic and anaerobic conditions acclimated a Rhodospirillum rubrum species to glucose assimilation. The modified or genetic variant Rs. rubrum strain has a glucose assimilation rate that is five times higher than the unmodified, non-variant, or wild-type Rs. rubrum strain. Genomic analyses revealed that genetic modifications in a gene cluster involved in xylitol assimilation are leading to the increased glucose assimilation capacity in the modified or variant Rs. rubrum strain. In particular, the modified or genetic variant Rs. rubrum strain comprises mutations in two genes that are part of the xylitol assimilation gene cluster, namely the Rru_A0247 gene encoding for the Lacl transcriptional regulator and the Rru_A0248 gene encoding for the inner-membrane translocator. Proteomic analyses revealed that the proteins encoded by this xylitol assimilation gene cluster were largely upregulated in the modified Rs. rubrum strain as compared to the non-modified Rhodospirillum microorganism.

[0065] Accordingly, a first aspect of the invention provides a genetic variant microorganism of the genus Rhodospirillum, wherein the expression or activity of one or more genes or gene products of the xylitol assimilation gene cluster is modified as compared to the expression or activity of said one or more genes or gene products in a non-variant, non-modified or wild-type Rhodospirillum microorganism, wherein the genes of the xylitol assimilation gene cluster are selected from theRru_A0247 gene encoding for the Lacl transcriptional regulator, the Rru_A0248 gene encoding for the inner-membrane translocator, the Rru_A0249 gene encoding for the ABC transporter and the Rru_A0250 gene encoding for xylulokinase. The genetic variant microorganism is typically characterized in that glucose assimilation is increased as compared to the non-variant or wild-type Rhodospirillum microorganism.

[0066] In some embodiments, the expression of one or more genes or gene products of the xylitol assimilation gene cluster is modified in the microorganism of the genus Rhodospirillum as compared to the expression of said one or more genes or gene products in a non-modified, or wild-type Rhodospirillum microorganism. In some embodiments, the activity of one or more genes or gene products of the xylitol assimilation gene cluster is modified in the microorganism of the genus Rhodospirillum as compared to the activity of said one or more genes or gene products in a nonmodified or wildtype Rhodospirillum microorganism. In some embodiments, the expression and activity of one or more genes or gene products of the xylitol assimilation gene cluster are modified in the microorganism of the genus Rhodospirillum as compared to the expression and activity of said one or more genes or gene products in a non-variant, non-modified or wildtype Rhodospirillum microorganism.

[0067] In some embodiments, a wild-type, non-modified or non-variant microorganism is modified by directed evolution, natural adaptation, or selection to obtain the genetic variant microorganism. In some embodiments, a wild-type, non-variant or -non-modified microorganism is modified by genetic engineering to obtain the genetic variant microorganism.

[0068] In some embodiments, the microorganism is a purple non-sulfur bacterium, in particular a bacterium of the genus Rhodospirillum. As non-limiting examples, the bacterial species may be selected among the group consisting of Rs. rubrum, Rs. centenum, Rs. photometricum, Rs. molischianum, Rs.fulvum, and Rs. salinarum. In a preferred embodiment, the microorganism is of the species Rs rubrum.

[0069] In a preferred embodiment, the genetic variant microorganism is a Rhodospirillum rubrum bacterial strain as deposited under the Budapest Treaty at the Belgian Coordinated Collections of Microorganisms (BCCM) on March 13, 2025 under Accession no. LMG P-34001, or a functional mutant thereof.

[0070] In some further embodiments, the genetic variant microorganism is a Rhodospirillum rubrum bacterial strain as deposited under the Budapest Treaty at the Belgian Coordinated Collections of Micro-organisms (BCCM) on March 13, 2025 under Accession no. LMG P-34001, or a functionalmutant thereof. In some embodiments, the genetic variant microorganism is a Rhodospirillum rubrum bacterial strain as deposited under the Budapest Treaty at the Belgian Coordinated Collections of Micro-organisms (BCCM) on March 13, 2025 under Accession no. LMG P-34001. Also provided is a microorganism that is a Rhodospirillum rubrum bacterial strain as deposited under the Budapest Treaty at the Belgian Coordinated Collections of Micro-organisms (BCCM) on March 13, 2025 under Accession no. LMG P-34001, or a functional mutation thereof. In some embodiments, the microorganism is a Rhodospirillum rubrum bacterial strain as deposited under the Budapest Treaty at the Belgian Coordinated Collections of Micro-organisms (BCCM) on March 13, 2025 under Accession no. LMG P-34001.

[0071] Preferably, the non-variant, or herein also referred to as the wildtype, non-modified, or parental, microorganism is selected from the microorganisms listed herein. In a particular embodiment, the non-modified or parental microorganism is selected from the Rs. rubrum, Rs. centenum, Rs. photometricum, Rs. molischianum, Rs. fulvum, and Rs. salinarum. More preferably, the nonmodified or parental microorganism is a Rs. rubrum species. In a particular embodiment, the nonmodified or parental microorganism is the Rs. Rubrum SIH strain; preferably the Rs. Rubrum SIH strain with ATCC number ATCC 25903.

[0072] As used herein, the term "microorganism" refers to all types of unicellular organisms, including prokaryotic organisms like bacteria, and eukaryotic organisms like yeasts and fungi, that can generally be found in nature. In the context of the present invention, the microorganism is preferably a bacterium, more preferably a heterotrophic bacterium.

[0073] As used herein, "bacterium", "bacteria", or "bacterial" refers in general to any prokaryotic organism, and may refer to an organism from Kingdom Eubacteria (Bacteria). In some cases, bacterial genera have been reassigned due to various reasons (such as, but not limited to, the evolving field of whole genome sequencing), and it is understood that such nomenclature reassignments are within the scope of any claimed genus.

[0074] As used herein, "bacterial strain" (which may be abridged to "strain" where context makes clear that a bacterial strain is meant) refers to any of the prokaryotic microorganism belonging to the same class of species, including the species. The term "strain" as a basic operational unit of microbial taxonomy, such as bacterial taxonomy, is frequently used to denote a population made up of the descendants of a single isolation in pure culture, usually made up of a succession ofcultures ultimately derived from an initial single colony. Where a species encompasses two or more distinct isolates, the term "strain" may be used to refer to an isolate or group of isolates that can be distinguished from other isolates of the same genus and species by phenotypic characteristics or genotypic characteristics or both.

[0075] As used herein, "functional mutant" or "functional homologue" refers to a microorganism of the genus Rhodospirillum that shares sufficient functional characteristics with the genetic variant microorganism as disclosed herein such that it retains the same biological properties of said microorganism, in particular such that the functional mutant or homologue microorganism is also able to assimilate glucose, more in particular such that the Lacl transcriptional regulator protein of the functional mutant or homologue microorganism also has diminished ability to bind to the xylitol assimilation gene cluster operator. In some embodiments, the functional homologue or mutant is a microorganism of the genus Rhodospirillum wherein the presence of one or more of the proteins selected from the Lacl transcriptional regulator, the inner-membrane translocator, the ABC transporter and xylulokinase is increased as compared to a non-variant microorganism. The functional homologue or mutant can be directly or indirectly obtained by further genetic modification (such as by random mutagenesis or by targeted genetic modification) of the genetic variant microorganism of the invention. The genetic modification of a functional homologue or mutantt can be achieved through any means, such as, but not limited to, chemical mutagens, ionizing radiation, transposon-based mutagenesis, or via conjugation, transduction, or transformation using the referenced microorganisms as either the recipient or donor of genetic material.

[0076] The term "genetic variant microorganism" or "variant microorganism" or "modified microorganism" refers to a microorganism or a strain of a microorganism that has been modified as compared to the wildtype or parental microorganism. This means, according to the usual meaning of these terms, that the microorganism of the invention is not found in nature and is modified when compared to a "non-modified" or "non-variant" or "wild-type" or "parental" microorganism, from which it is derived. The "non-modified", "wild-type", "non-variant", or "parental" microorganism may occur in nature (i.e. a wild-type microorganism) or may have been previously modified, but does not comprise the genetic modifications that are present in the genetic variant microorganism as disclosed herein. Accordingly, the genetic variant microorganisms of the invention have been modified so that the expression and / or activity of one or more genes or gene products of the xylitol assimilation gene cluster is modified as compared to the expression or activity of said one or more genes or gene products in a non-modified microorganism.In some embodiments, the genetic variant microorganism is modified as compared to the nonvariant microorganism by spontaneous mutations, such as by directed evolution or natural adaptation or selection.

[0077] In some embodiments, the genetic variant microorganism is a genetically modified microorganism. The term "genetically modified microorganism", also referred to as "recombinant microorganism", "genetically engineered microorganism", "bioengineered microorganism", or "biotechnologically enhanced microorganism" refers to a microorganism wherein one or more genes and / or the activity or expression of one or more genes or proteins are modified through genetic engineering.

[0078] A variety of genetic modifications may be made to the genetic variant microorganism of the invention, in particular wherein the expression or activity of one or more genes or gene products of the xylitol assimilation gene cluster is modified as compared to the expression or activity of said one or more genes or gene products in a non-modified microorganism. Such genetic modifications can be done by directed evolution, natural adaptation, or selection, or by genetic engineering. As a non-limiting example, endogenous genes can be attenuated, deleted, or over-expressed in the modified or variant microorganism, while exogenous genes can be introduced, carried by a plasmid, or integrated into the genome of the strain, for expression within the cell. Such modifications can be performed, for example, by adaptation (e.g. adaptive laboratory evolution), wherein a microorganism is cultured such that a specific stress is applied on the microorganism thereby inducing mutagenesis, or by forcing the development and evolution of new metabolic pathways by combining directed mutagenesis and evolution under specific selection pressure. Such modifications can also be performed by genetic engineering, such as site-specific mutagenesis, electroporation to introduce foreign DNA into the microorganism, or by gene editing (e.g. CRISPR-Cas9 mediated gene editing).

[0079] The term "gene" is well-known in the art and in general refers to a locatable region of genomic sequence, corresponding to a unit of inheritance, which is associated with regulatory genes, transcribed regions and / or other functional sequence regions. Genes typically comprise a coding sequence encoding a gene product, such as an RNA molecule or a polypeptide.

[0080] The term "protein" as used throughout this specification generally encompasses macromolecules comprising one or more polypeptide chains, i.e., polymeric chains of amino acid residues linked by peptide bonds. The term may encompass naturally, recombinantly, semi-synthetically, or synthetically produced proteins. The term also encompasses proteins that carry one or more co- or post-expression-type modifications of the polypeptide chain(s), such as, without limitation,glycosylation, acetylation, phosphorylation, sulfonation, methylation, ubiquitination, signal peptide removal, N-terminal Met removal, conversion of pro-enzymes or pre-hormones into active forms, etc. The term further also includes protein variants or mutants which carry amino acid sequence variations vis-a-vis a corresponding native protein, such as, e.g., amino acid deletions, additions and / or substitutions. The term contemplates both full-length proteins and protein parts or fragments, e.g. naturally-occurring protein parts that ensue from processing of such full-length proteins.

[0081] The term "polypeptide" as used throughout this specification generally encompasses polymeric chains of amino acid residues linked by peptide bonds. Hence, especially when a protein is only composed of a single polypeptide chain, the terms "protein" and "polypeptide" may be used interchangeably herein to denote such a protein. The term is not limited to any minimum length of the polypeptide chain. Without limitation, protein, polypeptides or peptides can be produced recombinantly by a suitable host or host cell expression system and isolated therefrom (e.g., a suitable bacterial, yeast, fungal, plant or animal host or host cell expression system), or produced recombinantly by cell-free transcription and / or translation, or non-biological protein, polypeptide or peptide synthesis.

[0082] The term "amino acid" as used herein refers to an organic compound containing both an amino group (-NH2) and a carboxyl group (-COOH), which serves as the fundamental building block of proteins. Unless otherwise specified, the term includes both natural and synthetic amino acids, as well as their derivatives, analogs, salts, esters, and modified forms. The definition encompasses both a-amino acids, as commonly found in peptides and proteins, and other amino acids with variations in their molecular structure.

[0083] The term "nucleic acid" as used throughout this specification typically refers to a polymer (preferably a linear polymer) of any length composed essentially of nucleoside units. A nucleoside unit commonly includes a heterocyclic base and a sugar group. Heterocyclic bases may include inter alia purine and pyrimidine bases such as adenine (A), guanine (G), cytosine (C), thymine (T) and uracil (U) which are widespread in naturally-occurring nucleic acids, other naturally-occurring bases (e.g., xanthine, inosine, hypoxanthine) as well as chemically or biochemically modified (e.g., methylated), non-natural or derivatised bases. The term "nucleic acid" further preferably encompasses DNA, RNA and DNA / RNA hybrid molecules, specifically including hnRNA, pre-mRNA, mRNA, cDNA, genomic DNA, amplification products, oligonucleotides, and synthetic (e.g., chemically synthesised) DNA, RNA or DNA / RNA hybrids. RNA is inclusive of RNAi (inhibitory RNA),dsRNA (double stranded RNA), siRNA (small interfering RNA), mRNA (messenger RNA), miRNA (micro-RNA), tRNA (transfer RNA, whether charged or discharged with a corresponding acylated amino acid), and cRNA (complementary RNA). A nucleic acid can be naturally occurring, e.g., present in or isolated from nature, can be recombinant, i.e., produced by recombinant DNA technology, and / or can be, partly or entirely, chemically or biochemically synthesized. A naturally occurring variant of a given sequence refers to all variants of the sequence which encode the same functional protein and that are present in or can be isolated from nature. Typically, this includes all variants of the sequence encountered in mammals, more particularly humans. It will be understood that variants from closely related species will have a higher sequence identity than variants from evolutionary more distant species. In particular embodiments, the natural variant of a given sequence has at least 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%; 90% or 95% sequence identity with the given sequence.

[0084] Without limitation, nucleic acids can be produced recombinantly by a suitable host or host cell expression system and isolated therefrom (e.g., a suitable bacterial, yeast, fungal, plant or animal host or host cell expression system), or produced recombinantly by cell-free transcription, or non-biological nucleic acid synthesis. A nucleic acid can be double-stranded, partly double-stranded, or single-stranded. Where single-stranded, the nucleic acid can be the sense strand or the antisense strand. In addition, the nucleic acid can be circular or linear.

[0085] The reference to any peptide, polypeptide, or nucleic acid, corresponds to the peptide, polypeptide, protein, or nucleic acid, commonly known under the respective designations in the art. The terms encompass such peptides, polypeptides, proteins, or nucleic acids, of any organism where found, and particularly of animals, preferably warm-blooded animals, more preferably vertebrates, yet more preferably mammals, including humans and non-human mammals, still more preferably of humans.

[0086] As used herein, a "genetic modification" refers to any alteration of the genetic material of an organism, including but not limited to the introduction, deletion, substitution, or rearrangement of nucleic acid sequences, whether induced by direct genetic engineering techniques or by adaptive evolution through prolonged exposure to specific environmental conditions. Such modifications may result from spontaneous mutations, selection pressure, genome rearrangements, horizontal gene transfer, or epigenetic changes that confer a stable and heritable phenotypic advantage. Direct genetic engineering techniques may be selected from recombinant DNA technology, genome editing using CRISPR, Transcription Activator-Like Effector Nucleases (TALENs), zinc finger Nucleases(ZFNs), or other molecular biology techniques. Genetic modifications may be introduced to achieve specific functional changes, such as enhanced expression of a gene, knockdown or knockout of a target gene, modification or regulatory elements, or the introduction of exogenous genetic material from the same or different species. Genetic modifications may be intentionally induced through laboratory-directed evolution, selective cultivation, or controlled environmental adaptation. Genetic modifications may also be intentionally induced through genetic engineering.

[0087] As used herein, the term "mutation" refers to any change in the nucleotide sequence of an organism's genetic material, including substitutions, deletions or rearrangements of nucleotides. Mutations may arise spontaneously due to errors in DNA replication or external factors such as radiation, chemicals, or prolonged environmental stress. They can be classified as point mutations, frameshift mutations, gene duplications, or chromosomal alterations. Mutation may lead to functional changes in gene expression, protein structure, or cellular processes, and can be either beneficial, neutral, or deleterious to the organism.

[0088] As used herein, the term "missense mutation" refers to a type of point mutation in which a single nucleotide change results in the substitution of one amino acid for another in the encoded protein. This alteration may affect protein function by modifying its structure, stability, or activity. Depending on the nature of the amino acid substitution, a missense mutation can have no significant impact, reduce enzymatic efficiency, or enhance biological activity.

[0089] In the context of the present invention, the expression and / or activity of one or more genes or gene products of the xylitol assimilation gene cluster is modified in the genetic variant microorganism as compared to the expression and / or activity of said one or more genes or gene products in a nonvariant Rhodospirillum microorganism.

[0090] In some embodiments, the expression of one or more genes or gene products of the xylitol assimilation gene cluster is modified in the genetic variant microorganism. In some embodiments, the activity of one or more gene products of the xylitol assimilation gene cluster is modified in the genetic variant microorganisms. In some embodiments, the expression and activity of one or more genes or gene products of the xylitol assimilation gene cluster is modified in the genetic variant microorganism as compared to the expression and activity of said one or more genes or gene products in a non-variant Rhodospirillum microorganism.

[0091] The "xylitol assimilation gene cluster" as used herein refers in general to a group of genes responsible for enabling bacteria to metabolize xylitol, a sugar alcohol commonly found in fruits and plants. Xylitol is metabolized via specific pathways that allows its use as a carbon and energysource. The genes in the xylitol assimilation gene cluster typically encode enzymes and transporters involved in xylitol uptake and conversion into intermediates that can enter central metabolic pathways like glycolysis or the pentose phosphatase pathway. Generally, the xylitol assimilation gene cluster includes at least a gene encoding for a xylitol transporter, a gene coding for a xylitol dehydrogenase, a gene coding for xylulose kinase, and one or more regulatory genes. In some embodiments, such as in the Rs rubrum species, the xylitol assimilation gene cluster comprises a transcriptional regulator gene (e.g., a Lacl transcriptional regulator gene), a xylitol dehydrogenase gene (xdh or similar), a xylulose kinase gene (e.g. D-xylulose kinase gene XylB or similar), one or more transporter genes (e.g. a D-xylose ABC transporter gene, a major facilitator family (MFS) transporter gene or a phosphortransferase system (PTS) transporter gene), and a translocator gene (e.g. inner-membrane translocator gene).

[0092] The xylitol assimilation gene cluster as described herein comprises at least the genes selected from the Rru_A0247 gene encoding for the protein Lacl transcriptional regulator, the Rru_A0248 gene encoding for the protein inner-membrane translocator, the Rru_A0249 gene encoding for the protein ABC transporter, and the Rru_A0250 gene encoding for the protein xylulokinase.

[0093] In some embodiments, in the genetic variant microorganism as disclosed herein, the expression or activity of one or more genes or gene products encoding for the proteins Lacl transcriptional regulator, inner-membrane translocator, ABC transporter, and / or xylulokinase is modified as compared to the expression or activity of said genes or gene products in a non-variant microorganism.

[0094] In some embodiments, in the genetic variant microorganism as disclosed herein, the expression or activity of the gene or gene product encoding for the protein Lacl transcriptional regulator is modified, optionally in combination with modification of the expression or activity of the gene or gene product encoding for one or more genes encoding for the proteins inner-membrane translocator, ABC transporter and / or xylulokinase.

[0095] In some embodiments, in the genetic variant microorganism as disclosed herein, the expression or activity of the gene or gene product encoding for the protein Lacl transcriptional regulator is modified, in combination with modification of the expression or activity of the gene or gene product encoding for one or more genes encoding for the proteins inner-membrane translocator, ABC transporter and / or xylulokinase.

[0096] In some embodiments, in the genetic variant microorganism as disclosed herein, the expression or activity of the gene or gene product encoding for the protein Lacl transcriptional regulator ismodified, in combination with modification of the expression or activity of the gene or gene product encoding for the proteins inner-membrane translocator, ABC transporter and xylulokinase.

[0097] In some embodiments, the expression or activity of the gene encoding for the Lacl transcriptional regulator (Rru_A0247 gene) or of the Lacl transcriptional regulator protein is modified as compared to a non-variant microorganism. In some particular embodiments, the expression of the gene encoding for the Lacl transcriptional regulator (Rru_A247 gene) is modified as compared to the expression of said gene in a non-variant microorganism. In some embodiments, the activity of the Lacl transcriptional regulator protein is modified as compared to said protein in a non-variant microorganism. In some embodiments, the wild-type form of the Rru_A0247 gene comprises the nucleotide sequence as set forth in SEQ ID NO: 1.

[0098] As used herein, the "Lacl transcriptional regulator", also referred to as the "Lacl-type transcriptional regulator", "periplasmic binding protein", or shortly "Lacl", is commonly associated with metabolic gene clusters in bacteria, including the xylitol assimilation gene cluster. Lacl transcriptional regulators typically function as repressors or activators that control expression of metabolic genes. In the absence of xylitol, the Lacl transcription regulator protein binds to the operator region of the gene cluster, thereby blocking transcription. When xylitol is present, it may act as an inducer, binding to the Lacl transcriptional regulator protein causing a conformational change that reduces its affinity for the operator, thereby allowing transcription of the gene cluster.

[0099] By means of further guidance, the gene encoding for the Lacl transcriptional regulator protein disclosed herein is annotated and available in the KEGG database as Rru_A0247 gene, which is the gene encoding the Lacl transcriptional regulator (or periplasmic binding protein) in an non-variant Rs rubrum strain, in particular in the non-variant Rs. rubrum SIH strain (ATCC 25903) or the non-variant Rs. rubrum strain ATCC11170. The reference nucleotide sequence of the Rru_A0247 gene is by means of example reproduced below (SEQ ID NO: 1): atgaagaagcttcttcttaccgcctgcgccgccgccgccctgctctcggcctcggccgcgatggccgccgacgcccccaaggcgcgcatcgcc gtgctgatgtatggcaataaggccgaattcgtccagttgatggagcgctatggcaaggagcatcccgccgtgaaggccgggatcgccgagg tgacgttctatgacggacgctatgacgccgccgtccagaacgatcaggcgcagatggcgatcaacaccaagcaggacgccatcgtcgtcaa cccgatggactatgaagccaacatcgatatcgccaccaacgccaagatggccgggatcccggtggtggtgaccaacgcccgcctcaacacc gacgagatgaccgccgaagtggtctccgacgacgtgctcggcggctatctggaagccaaggacgtgctgaccaagcttggctgcaagggca acgtcgtgatcatcgaggggccgaagggcggctcgggcgagatccagcgtggtcagggcaacgaaaaggccctggccgaatgcccggccg gcgcggtgaaggtgctcgagcgcaagaccgccaattggtcgcgcgccgaggcccttgatctgatgcagaactggctgagcaagcacccggg caagatcaacggcgtcatcggccagaacgatgaaatggcgctcggcgccatcgaggcgatcaaggccgccgacctcaacgtcaaggatttcgccatcgccggcatcgacggcgtgaccgatgccctgcacgcggtcaaggccggcgagatgacctcgatccttcaggacgcccgtggccaga tccagggcagcatcgacgtcgccctgcgcgccgtgaagggccccgactacaagccgatgtcgccgatctgggaacagtacaaggccgacct cgcctgggccgatggccagtccaagcgctatgacatcccctggaccgtggtgaccacggccaatgtcgacgagctgctgaaagaccgcaat taa (SEQ ID NO: 1).

[0100] The protein encoded by the Rru_A0247 gene is the Lacl transcriptional regulator protein. The reference Lacl transcriptional regulator protein sequence is annotated under NCBI Genbank accession number ABC21052. The amino acid sequence of the Lacl transcriptional regulator protein of the non-variant Rs. rubrum strain with accession number ABC21052 is annotated in Uniprot (www.uniprot.or ) under accession number Q2RXU3, and is by means of example reproduced below (SEQ ID NO: 2):

[0101] MKKLLLTACAAAALLSASAAMAADAPKARIAVLMYGNKAEFVQLMERYGKEHPAVKAGIAEVTFYDGRYDAA VQNDQAQMAINTKQDAIVVNPMDYEANIDIATNAKMAGIPVVVTNARLNTDEMTAEVVSDDVLGGYLEAKD VLTKLGCKGNVVIIEGPKGGSGEIQRGQGNEKALAECPAGAVKVLERKTANWSRAEALDLMQNWLSKHPGKIN GVIGQNDEMALGAIEAIKAADLNVKDFAIAGIDGVTDALHAVKAGEMTSILQDARGQIQGSIDVALRAVKGPDY KPMSPIWEQYKADLAWADGQSKRYDIPWTVVTTANVDELLKDRN (SEQ ID NO: 2).

[0102] In some embodiments, the expression or activity of the gene encoding for the inner-membrane translocator protein (Rru_A248 gene) or of the inner-membrane translocator protein is modified as compared to a non-variant microorganism. In some particular embodiments, the expression of the gene encoding for the inner-membrane translocator (Rru_A0248 gene) is modified as compared to the expression of said gene in a non- variant microorganism. In some embodiments, the activity of the inner-membrane translocator protein is modified as compared to said protein in a non- variant microorganism. In some embodiments, the wild-type form of the Rru_A0248 gene comprises the nucleotide sequence as set forth in SEQ ID NO: 3.

[0103] As used herein, the inner-membrane translocator protein is a translocator responsible for the uptake of xylitol across the bacterial cell membrane. It is a protein embedded in the inner membrane that facilitates the transport of xylitol from the external environment into the cytoplasm.

[0104] By means of further guidance, the gene encoding for the inner-membrane translocator protein disclosed herein is annotated and available in the KEGG database as Rru_A0248 gene, which is thegene encoding the inner-membrane translocator in an non-modified Rs. rubrum strain, in particular in the non-modified Rs. rubrum SIH strain (ATCC 25903) or the non-variant Rs. rubrum strain ATCC11170. The reference nucleotide sequence of the Rru_A0248 gene is by means of example reproduced below (SEQ ID NO: 3): atgcacatcacccagccggccgccaaggccccgatctccttgcgaaagtacggaatcgtcttcgcatttctcgggctctgcgtgttggtcagc gcgctctgccagctcaaggtggtccagggcgcctggcccgagaacaccttcctgaccgtcaataatctgatgctgatcttgcatcagatatcg gtgaacggcgtccttgccgtcggcatgaccttcgtcgtcatctcggccggcatcgatttgtcggtgggctcggtcctggccttttccgggatgat ggccgcctcgatggccacccgctcggtcggggtgacgccatggagcgacacctatccggtgatcttcccgatcatcgccgccctgggcgtcg gcgcgctgtgcggcggcttaagcggctggatcatcgcccgtttccgcatccaggccttcatcgccaccctgggcatgctgctggcggcgcgcg gcttcaccatgtcggtcaccggcggcaatccgatttcgggcctaagcccggatttccgctggttcggcacgggcaagctgttcgaggtgatcc cggtgccggtggtcatcctcgccctggtcttccttctggcctgggtgatcctcaataaaacggtctttggccgctacgtctatgccgttggcggc aacgagaagagcgcgcgcacctcgggcatcaacaccggggcgatcctcatctgggtctatgtggtcgccggcttcctggccggcgtggccgg ggtgatcctgaccgccaagaccgggtcggcccagaccagcgccggcagttcctatgaacttgacgccatcgccgccgtggtcatcggcggcg ccagcctggccggcggcgtcggccggctgacgggtacgtttttcggggccctgatcatcggcgtgatgaacaacggcctcgatatcctgggg gtccagagcttctaccagctcatcatcaaaggcggactgatcgttgtcgccgtgatcctcgacccctcaagaaaacaggctggttga (SEQ ID NO: 3)

[0105] The protein encoded by the Rru_A0248 gene is the inner-membrane translocator protein. The reference inner-membrane protein sequence is annotated under NCBI Genbank accession number ABC21053. The amino acid sequence of the inner-membrane translocator protein of the nonvariant Rs. rubrum strain with accession number ABC21053 is annotated in Uniprot (www.uniprot.org) under accession number Q2RXU2, and is by means of example reproduced below (SEQ ID NO: 4):

[0106] MHITQPAAKAPISLRKYGIVFAFLGLCVLVSALCQLKVVQGAWPENTFLTVNNLMLILHQISVNGVLAVGMTFV VISAGIDLSVGSVLAFSGMMAASMATRSVGVTPWSDTYPVIFPIIAALGVGALCGGLSGWIIARFRIQAFIATLG MLLAARGFTMSVTGGNPISGLSPDFRWFGTGKLFEVIPVPVVILALVFLLAWVILNKTVFGRYVYAVGGNEKSAR TSGINTGAILIWVYVVAGFLAGVAGVILTAKTGSAQTSAGSSYELDAIAAVVIGGASLAGGVGRLTGTFFGALIIGV MNNGLDILGVQSFYQLIIKGGLIVVAVILDPSRKQAG (SEQ ID NO: 4).

[0107] In some embodiments, the expression or activity of the gene encoding for xylulokinase (Rru_A250 gene) or of the xylulokinase protein is modified as compared to a non-variant microorganism. Insome particular embodiments, the expression of the gene encoding for xylulokinase (Rru_A250 gene) is modified as compared to the expression of said gene in a non-variant microorganism. In some embodiments, the activity of xylulokinase protein is modified as compared to said protein in a non-variant microorganism.

[0108] As used herein, xylulokinase is also present in the xylitol assimilation gene cluster. Xylulokinase plays a crucial role in the pathway catalyzing the phosphorylation of D-xylulose, produced from xylitol by xylitol dehydrogenase, to D-xylulose-5-phosphate, which can then enter the pentose phosphate pathway.

[0109] By means of further guidance, the xylulokinase protein disclosed herein is encoded by the D-xylulose kinase gene (e.g. xylB). The gene encoding for the xylulokinase protein disclosed herein is annotated and available in the KEGG database as Rru_A0250 gene, which is the gene encoding the xylulokinase in a non-variant Rs. rubrum strain, in particular in the non-variant Rs. rubrum SIH strain (ATCC 25903) or the non-variant Rs. rubrum strain ATCC11170. The reference nucleotide sequence of the Rru_A0250 gene is by means of example reproduced below (SEQ. ID NO: 5):

[0110] ATGTTTCTTGGCATCGACTGCGGAACCCAGGGCACCAAGGCCCTGATCCTTGACGACAGCGGCGCCATCCG CGGCGTCGGCCATGCCGCGCACCGCTTGATCGAGCGCGAAAGCGGGGCGCGCGAACAAGATCCGGCGTG GTGGGTGCAAGCCGCCATCGGCGCGGTCAAGGGCGCCCTGGCCGAGGCCGGGATCGACGGATCGGCGGT GCGCGCCCTGGCCTTTTCCGGCCAGCAGCACGGGCTGGTGGTTCTGGGCAAGGACGGCCAGCCGCTGCGC CCGGCCAAGCTGTGGAACGATACGGAAACGGCGGCGCAGAACGCCGTCCTGGTCGAGCGCCTGGGCGGC GCCGAGGCCTGGGGCGAGCGGCTGGGCATCGTGCCGCTGACCGGCTATACGGTTTCCAAGCTGTTGTGGC TGAAGGACAACGAGCCCGAGGCCTTCGCCCGGATCGACGCCATCCTGCTGCCCCATGATTACCTGAATTTC TGGGCGACCGGTCGGCGGGTCGCCGAAGCCGGCGACGCCTCGGGCACGGCGTTCTTCGATATCCGCGCCC GCCGCTGGTCCGAAGAGGTGTTGGCCCTGATCGATGGCGGCAGCGGCCATCTGGCCCGCGCCCTGCCCGA GTTGATCGGTCCCGACGCCATCGTCGGCCCGCTGCGCCCCGAAGCCGCCACCGCCCTTGGTCTGTCCCCCA CCTGTCTGGTGGCGGCGGGGGGCGGCGACAACATGATGGGCGCCATCGGCACCGGCAACGTCCGCGAAG GCGTGGTGACGCTGAGCATCGGCACCTCGGCCGCCGTCTATTCCTATAGTGACACCCCCGTCGTCGACCCG CGCGGCCGGGTCGCGGCGTTTTGTTCAAGCAGCGGCGGCTGGTTGCCGCTGGTCTGCACCATGAACGCCA CCAATGTCACCGGTCGCGCCGCCACCTTGGTCGGCGACGATGTCGGAGCGATCGACCGCGCCCTGGCCGA CAGCCCGCCGGGCGCCGAGGGCATCACCGTTCTGCCCTTCCTCAATGGCGAGCGCACCCCCGATCTGCCCG CCGCGCGCGGCAGCGTGCTTGGTCTGTCGGTCACCAACATGACCGCACCCAATCTGCTGCGCGCCATGACC GAGGGCGTCAGCTTCGGCATGTTGGCCGGGCTGAAGCTGGTGCTAGCCGGCCGCCAGCCCGAGCGGGTCT TCGTCATCGGCGGCGGGGCGCGCAGCGGCGAATGGCGCAAGATGATCGCCGATGCCAGCGGCGCGGAAATCGTCGTGCCGATGACCGAAGAGGCCGGCAGCCTTGGCGCGGCGATCCAGGCCCAATGGGCGTGGAGCG GCGAGAGCGGCGCGCCGATCGCCCTTGGCGATCTGACCGACAGGGCGGTGCGCGTTGACGAGACCAAGG GCGCCCTGCCCCGTCCCGAGCGCCGCGCCGCCTATGACGAGGCCTTCGGCCGCTACCGGGAAAGCCTGAT GCGCTTGCATGGCGTCGACGCCCTTTGA (SEQ ID NO : 5)

[0111] The protein encoded by the Rru_A0250 gene is the xylulokinase protein. The reference xylulokinase protein sequence is annotated under NCBI Genbank accession number ABC21055. The amino acid sequence of the xylulokinase protein, of the non-variant Rs. rubrum strain with accession number ABC21055 is annotated in Uniprot (www.uniprot.org) under accession number Q2RXU0, and is by means of example reproduced below (SEQ ID NO: 6):

[0112] MFLGIDCGTQGTKALILDDSGAIRGVGHAAHRLIERESGAREQDPAWWVQAAIGAVKGALAEAGIDGSAVRAL AFSGQQHGLVVLGKDGQPLRPAKLWNDTETAAQNAVLVERLGGAEAWGERLGIVPLTGYTVSKLLWLKDNEP EAFARIDAILLPHDYLNFWATGRRVAEAGDASGTAFFDIRARRWSEEVLALIDGGSGHLARALPELIGPDAIVGPL RPEAATALGLSPTCLVAAGGGDNMMGAIGTGNVREGVVTLSIGTSAAVYSYSDTPVVDPRGRVAAFCSSSGG WLPLVCTMNATNVTGRAATLVGDDVGAIDRALADSPPGAEGITVLPFLNGERTPDLPAARGSVLGLSVTNMTA PNLLRAMTEGVSFGMLAGLKLVLAGRQPERVFVIGGGARSGEWRKMIADASGAEIVVPMTEEAGSLGAAIQA QWAWSGESGAPIALGDLTDRAVRVDETKGALPRPERRAAYDEAFGRYRESLMRLHGVDAL (SEQ ID NO : 6)

[0113] In some embodiments, the expression or activity of the gene encoding for the ABC transporter (Rru_A0249 gene) or of the ABC transporter protein is modified as compared to a non-variant microorganism. In some particular embodiments, the expression of the gene encoding for the ABC transporter (Rru_A0249 gene) is modified as compared to the expression of said gene in a non-variant microorganism. In some embodiments, the activity of the ABC transporter protein is modified as compared to said protein in a non-variant microorganism.

[0114] By means of further guidance, the ABC transporter protein disclosed herein is encoded by the ABC transporter gene (Rru_A0249). The gene encoding for the ABC transporter protein disclosed herein is annotated and available in the KEGG database as Rru_A0249 gene, which is the gene encoding the ABC transporter in a non-variant Rs. rubrum strain, in particular in the non-variant Rs. rubrum SIH strain (ATCC 25903) or the non-variant Rs. rubrum strain ATCC11170. The reference nucleotide sequence of the Rru_A0249 gene is by means of example reproduced below (SEQ ID NO: 7): atgtcctcccctcttctgacgatgcgcggtatccgcaagagctatgccggggttcatgccctggtcgatggcaatctcgacctggaacgcggg cagatccatgcgctttgcggtggcaatggcgcggggaaatcgaccatcctcggcatcttgatgggcttcacccgccccgattgcggcgagatccgcatcgagggcaagccggtcagcttcgccaatccgacccaggccctgcaggccggcatcgccatcgtccagcaggaactgagcggcgtcc cccacctgacggtggccgagaacatctatctcggcgccgaaccgcgccgccgcggcttcgtcgacttcccgcaattgaaccgtcaggccgag gagctgctggcctcgcttggcttcgacatcgatccccgcgtccccttggcctcgctcagcatcgcctcgcagcagttgatcgagatcgccaagg ctttatcgcggcgcgatgccgatatcctcatcttcgacgaaccgacctcggccatcggcgagaaggacaccctgcgcctgttcgaggtgctgc gcgatctggcggcggcgggcaagggcatcatctatgtcacccaccgtctggccgaggtcttcaccatcgccgacagctatacggtgttcaag gacggggcgcggatcgaaaccggccgggtcgccgacatcacccgcgaaaagctgatcgaatcgatgatcggcggcgccatcgaaggcga atacgtcaaagagaacgtgcccagcgaccggcctttgctcgatgtgcgcggcctcagccgggcgccgtggttcgatcgggtgagtttcaccct gcatgccggcgagatcctcggcatctatggtctggtcggctcgggccgcagccagcttcttgataccatctacggcctttatcccgccgatgcg ggaacggtgtgggtggaggggcgcgagatccgcccgggacgggtgcgcgcggccctgggcgcggggatctcctatgtcaccgaggaccgc aagcatagcggtctggtgctctgcgcttcggtcggcgacaatctttcgctgtcgcaactgccccatatccagcgcttcggcttcatccgcaccg ccctggaacgggcgggcatcgacgattcgatcgccaagatgcggatcaaaacgccggggcccgagcagatcgtgcgcaacctcagcggcg gcaatcagcaaaaggtcgtcttcggccgctgcacctcgatcggccccaaggttctgctgcttgatgaaccgacgcgcggcgtcgatgtcggc gccaaaaaggaaatctaccgcttcgtctccgatttcaccaaagccggcggcgcggttctgatggtgtcttcggaactcgacgagatcaccgg catgagcgatcgcatcatcgtcatcaaaaagggcgcccatgtcgccgaattcccccgggaagagacgacgcagaaggccctgatgatggcc gccgtctaa (SEQ ID NO: 7)

[0115] The protein encoded by the Rru_A0249 gene is the ABC transporter protein. The reference ABC transporter protein sequence is annotated under NCBI Genbank accession number ABC21054. The amino acid sequence of the ABC transporter protein, of the non-variant Rs. rubrum strain with accession number ABC21054 is annotated in Uniprot (www.uniprot.org) under accession number Q2RXU1, and is by means of example reproduced below (SEQ ID NO: 8):

[0116] MSSPLLTMRGIRKSYAGVHALVDGNLDLERGQIHALCGGNGAGKSTILGILMGFTRPDCGEIRIEGKPVSFANPT QALQAGIAIVQQELSGVPHLTVAENIYLGAEPRRRGFVDFPQLNRQAEELLASLGFDIDPRVPLASLSIASQQLIEI AKALSRRDADILIFDEPTSAIGEKDTLRLFEVLRDLAAAGKGIIYVTHRLAEVFTIADSYTVFKDGARIETGRVADITR EKLIESMIGGAIEGEYVKENVPSDRPLLDVRGLSRAPWFDRVSFTLHAGEILGIYGLVGSGRSQLLDTIYGLYPADA GTVWVEGREIRPGRVRAALGAGISYVTEDRKHSGLVLCASVGDNLSLSQLPHIQRFGFIRTALERAGIDDSIAKM RIKTPGPEQIVRNLSGGNQQKVVFGRCTSIGPKVLLLDEPTRGVDVGAKKEIYRFVSDFTKAGGAVLMVSSELDEI TGMSDRIIVIKKGAHVAEFPREETTQKALMMAAV (SEQ ID NO: 8)

[0117] In some embodiments, the genetic variant microorganism as disclosed comprises a genetic modification, preferably a mutation, more preferably a missense mutation, in one or more genes of the xylitol assimilation gene cluster that comprises the genes encoding for the Lacl transcriptionalT1

[0118] regulator, the inner-membrane translocator, the ABC transporter, and xylulokinase, as compared to the non-variant or wild-type Rhodospirillum microorganism.

[0119] In some embodiments, the genetic variant microorganism comprises a genetic modification, preferably a mutation, more preferably a missense mutation, in the Rru_A0247 gene encoding for the Lacl transcriptional regulator.

[0120] In some embodiments, the genetic variant microorganism comprises a genetic modification, preferably a mutation, more preferably a missense mutation, in the Rru_A248 gene encoding for the inner-membrane translocator.

[0121] In some embodiments, the genetic variant microorganism comprises a genetic modification, preferably a mutation, more preferably a missense mutation, in the Rru_A0249 gene encoding for the ABC transporter.

[0122] In some embodiments, the genetic variant microorganism comprises a genetic modification, preferably a mutation, more preferably a missense mutation, in the Rru_A0250 gene encoding for xylulokinase.

[0123] In some embodiments, the genetic variant microorganism comprises a genetic modification, preferably a mutation, more preferably a missense mutation, in the Rru_A0249 gene encoding for the Lacl transcriptional regulator, and in one or more genes of the Rru_A0248 gene encoding for the inner-membrane translocator, the Rru_A0249 gene encoding for the ABC transporter and the Rru_A0250 gene encoding for xylulokinase.

[0124] In some embodiments, the genetic variant microorganism comprises a genetic modification, preferably a mutation, more preferably a missense mutation, in the Rru_A0247 gene encoding for the Lacl transcriptional regulator and in the Rru_A0248 gene encoding for the inner-membrane translocator.

[0125] In some embodiments, the genetic variant microorganism comprises genetic modifications, preferably mutations, more preferably missense mutations, in the Rru-_A0247 gene encoding for the Lacl transcriptional regulator, in the Rru_0248 gene encoding for the inner-membrane translocator, in the Rru_0249 gene encoding for the ABC transporter and in the Rru_0250 gene encoding for xylulokinase.

[0126] In some embodiments, the genetic variant microorganism comprises a Lacl transcriptional regulator protein with an amino acid substitution at position 43 as compared to the Lacl transcriptionalregulator protein in the non-variant Rhodospirillum microorganism, wherein the amino acid sequence of the Lacl transcriptional regulator protein in the non-variant Rhodospirillum is represented by SEQ ID NO: 2. In some embodiments, the genetic variant microorganism comprises a single amino acid substitution at position 43 as compared to the Lacl transcriptional regulator protein in the non-variant Rhodospirillum. In some embodiments, the genetic variant microorganism comprises a proline at the amino acid position corresponding to amino acid position 43 of SEQ NO: 2. In some embodiments, the Lacl transcriptional regulator protein in the genetic variant microorganism comprises an amino acid sequence as in SEQ ID NO: 9.

[0127] In some embodiments, the genetic variant microorganism comprises a gene for encoding the Lacl transcriptional regulator wherein the gene comprises a polynucleotide sequence as defined in SEQ ID NO: 10.

[0128] In some embodiments, the genetic variant microorganism comprises an inner-membrane translocator protein with an amino acid substitution at position 320 as compared to the inner-membrane translocator protein in the non-modified Rhodospirillum microorganism, wherein the amino acid sequence of the inner-membrane translocator protein in the non-modified Rhodospirillum is represented by SEQ ID NO: 4. In some embodiments, the genetic variant microorganism comprises a single amino acid substitution at position 320 as compared to the inner-membrane translocator protein in the non-variant Rhodospirillum. In some embodiments, the genetic variant microorganism comprises a glutamic acid at the amino acid position corresponding to amino acid position 320 of SEQ NO: 4. In some embodiments, the inner-membrane translocator protein in the genetic variant microorganism comprises as amino acid sequence as in SEQ ID NO: 11.

[0129] In some embodiments, the genetic variant microorganism comprises a gene for encoding the inner-membrane translocator wherein the gene comprises a polynucleotide sequence as defined in SEQ ID NO: 12.

[0130] In some embodiments, the genetic variant microorganism comprises a gene for encoding the Lacl transcriptional regulator wherein the gene comprises a polynucleotide sequence as defined in SEQ ID NO: 10, and a gene for encoding the inner-membrane translocator wherein the gene comprises a polynucleotide sequence as defined in SEQ ID NO: 12.

[0131] In some embodiments, the genetic variant microorganism comprises a Lacl transcriptional regulator protein that comprises an amino acid sequence as in SEQ ID NO: 9, and an inner-membrane translocator protein that comprises as amino acid sequence as in SEQ ID NO: 11.In some embodiments, the genetic variant microorganism may further comprise a genetic modification, preferably a mutation, more preferably a missense mutation, in one or more of the genes listed in Table 1. In some embodiments, the genetic variant microorganism may further comprise a genetic modification, preferably a mutation, more preferably a missense mutation, in all genes listed in Table 1.

[0132] In some embodiments, the genetic variant microorganism may comprise a mutation in the gene with KEGG Gene ID Rru_A0008, in particular the genetic variant may comprise a gene with KEGG Gene ID Rru_A0008 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 13. In some embodiments, the genetic variant microorganism may comprise a mutation in the ABC transporter gene with KEGG Gene ID Rru_A0011, in particular the genetic variant may comprise an ABC transporter gene with KEGG Gene ID Rru_A0011 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 14.

[0133] In some embodiments, the genetic variant microorganism may comprise a mutation in the CRISPR-associated endonuclease Csnl gene with KEGG Gene ID Rru_A0453, in particular the genetic variant may comprise a CRISPR-associated endonuclease Csnl gene with KEGG Gene ID Rru_A0453 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 15.

[0134] In some embodiments, the genetic variant microorganism may comprise a mutation in the TPR repeat-containing gene with KEGG Gene ID Rru_A1817, in particular the genetic variant may comprise a TPR repeat-containing gene with KEGG Gene ID Rru_A1817 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 16.

[0135] In some embodiments, the genetic variant microorganism may comprise a mutation in the phosphohistidine phosphatase Six A gene with KEGG Gene ID Rru_A2162, in particular the genetic variant may comprise a phosphohistidine phosphatase Six A gene with KEGG Gene ID Rru_A2162 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 17.

[0136] In some embodiments, the genetic variant microorganism may comprise a mutation in the gene with KEGG Gene ID Rru_A2588, in particular the genetic variant may comprise a gene with KEGG Gene ID Rru_A2588 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 18. In some embodiments, the genetic variant microorganism may comprise a mutation in the DEAD / DEAH box helicase gene with KEGG Gene ID Rru_A2718, in particular the genetic variant may comprise a DEAD / DEAH box helicase gene with KEGG Gene ID Rru_A2718 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 19.In some embodiments, the genetic variant microorganism may comprise one or more mutations in the chemotaxis sensory transducer gene with KEGG Gene ID Rru_A3241, in particular the genetic variant may comprise a chemotaxis sensory transducer gene with KEGG Gene ID Rru_A3241 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 20.

[0137] Table 1. Additionally mutated genes in some embodiments of the genetic variant microorganism of the invention.

[0138] Gene name Gene ID in KEGG Protein description NCBI Protein ID UniProt ID database

[0139] Uncharacterized Rru_A0008 Hypothetical protein ABC20813 Q2RYI2 gene

[0140] ABC transporter Rru_A0011 ABC transporter protein ABC20816 Q2RYH9 component

[0141] CRISPR-associated Rru_A0453 CRISPR-associated ABC21258 Q2RX87 endonuclease Csnl endonuclease Csnl family

[0142] protein

[0143] TPR repeat Rru_A1817 TPR repeat-containing ABC22617 Q2RTC8

[0144] protein

[0145] Phosphohistidine Rru_A2162 Phosphohistidine ABC22962 Q2RSD3 phosphatase gene phosphatase, Six A

[0146] Hypothetical gene Rru_A2588 Hypothetical protein ABC23385 Q2RR60 DEAD / DEAH box Rru_A2718 DEAD / DEAH box helicase ABC23515 Q2RQT0 helicase gene

[0147] Chemotaxis Rru_A3241 Chemotaxis sensory ABC24036 Q2RPA9 sensory transducer transducer protein

[0148] gene

[0149]

[0150] In some further embodiments, the genetic variant microorganism comprises a gene with KEGG Gene ID Rru_A0008 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 13, an ABC transporter gene with KEGG Gene ID Rru_A0011 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 14, a CRISPR-associated endonuclease Csnl gene with KEGG Gene ID Rru_A0453 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 15, a TPR repeatcontaining gene with KEGG Gene ID Rru_A1817 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 16, a phosphohistidine phosphatase Six A gene with KEGG Gene ID Rru_A2162 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 17, a gene with KEGG Gene ID Rru_A2588 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 18, a DEAD / DEAH box helicase gene with KEGG Gene ID Rru_A2718 wherein said gene comprises a nucleotidesequence as in SEQ ID NO: 19, and a chemotaxis sensory transducer gene with KEGG Gene ID Rru_A3241 wherein said gene comprises a nucleotide sequence as in SEQ ID NO: 20.

[0151] Table 2. Nucleotide or amino acid sequences of SEQ ID NO.9 to 20.

[0152] SEQ Nucleotide or amino acid sequence

[0153] ID NO

[0154] 9 MKKLLLTACAAAALLSASAAMAADAPKARIAVLMYGNKAEFVPLMERYGKEHPAVKAGIAEVTF

[0155] YDG RYDAAVQN DQAQM Al NTKQDAI VVN PM DYEAN 1 DI ATN AKM AGI PVVVTN ARLNTDEMTAE VVSDDVLGGYLEAKDVLTKLGCKGNVVIIEGPKGGSGEIQRGQGNEKALAECPAGAVKVLERKT ANWSRAEALDLMQNWLSKHPGKINGVIGQNDEMALGAIEAIKAADLNVKDFAIAGIDGVTDAL HAVKAGEMTSILQDARGQIQGSIDVALRAVKGPDYKPMSPIWEQYKADLAWADGQSKRYDIP WTVVTTANVDELLKDRN

[0156] 10 CAAGGCGCGCATCGCCGTGCTGATGTATGGCAATAAGGCCGAATTCGTCCCGTTGATGGAG CGCTATGGCAAGGAGCATCCCGCCGTGAAGGCCGGGATCG

[0157] 11 MHITQPAAKAPISLRKYGIVFAFLGLCVLVSALCQLKVVQGAWPENTFLTVNNLMLILHQISVNG VLAVGMTFVVISAGIDLSVGSVLAFSGMMAASMATRSVGVTPWSDTYPVIFPIIAALGVGALCG GLSGWIIARFRIQAFIATLGMLLAARGFTMSVTGGNPISGLSPDFRWFGTGKLFEVIPVPVVILAL VFLLAWVILNKTVFGRYVYAVGGNEKSARTSGINTGAILIWVYVVAGFLAGVAGVILTAKTGSAQ TSAGSSYELDAIAAVVIGGASLAGGVGRLTGTFFGALIIGVMNNGLDILGVQSFYQLIIEGGLIVV AVILDPSRKQAG

[0158] 12 ACAACGGCCTCGATATCCTGGGGGTCCAGAGCTTCTACCAGCTCATCATCGAAGGCGGACTGATCGTTGTCGCCGTG ATCCTCGACCCCTCAAGAAAACAG

[0159] 13 AAGGCGCCCTTCGATGTGCGCATCGCCGGCCTGTCGGACGACCTGCGCCGGAAGACCATCGAACTGTATTTCGAATC CGCCGAGGATCTCACGGCCTTCAA

[0160] 14 GCCCCGGGACGAACCGGCGACCCCGGCGGCGACGCCCGCGCGCGAGGACGCGCCGCCGCGCCCCCTGCCCTTCGGA CTGGCCGCCGTCGGCCTGGGCAAAC

[0161] 15 TGGCCGATGACCTGGATCGCGGCCAACCGGTGCGCATGCGCTATAACCAACGCGACCGCGACGGCGTGGTCGCCCC CACCCGCGCCCTGATCGCCGAGGAA

[0162] 16 GCAACCAAGTATTAAAAGCTGCCTTTGTAGCTAGTCGTGATGCCAACAATTAGATAGTTCAAATCTATCTGAAGGAGG CCATCCCGGAAATGCCCGGGGCA

[0163] 17 CAAGACCCAGAAGTCGACGATTTCGATCGACCACTCTCGGCGCGCGGCCGGCGCGCCGGCCGCCTGATCGGTTTGTC CCTGGCGAGGCGGACCGACCCGCC

[0164] 18 GCCGCCGCCCGATGAAACGCCCGACCTGCGCGCCGCCCTGGCCGAGCGCGCGGCCGAGGTGGCGGCCCTGAACGCC CGGCTGGCCGCCAGTCAGGCCCGCC

[0165] 19 AGGAAGCCCTGGCCGATGCCGGTTTGCTGGTCGAAGCCGAAGAGCCCGAACACGACTCCGACTTCGTCCCCGCCCCC GGCCTTGCCGCCCGCGAGATCGAG

[0166] 20 AATGACCACGGTGACCCAGGCGGCCGAAGAGACCGGCGGCGCGGCGCGCCCGCGTCGTGACGGCCTCGACGGCCT GGGTCACAAATCGGCGCGCCTAACCA

[0167]

[0168] In some embodiments, the expression or activity of one or more genes or gene products of the xylitol assimilation gene cluster in the genetic variant microorganism of the invention is increased as compared to the expression or activity of said one or more genes or gene products in a nonvariant Rhodospirillum microorganism.

[0169] In some embodiments, the expression or activity of one or more genes or gene products of the xylitol assimilation gene cluster in the genetic variant microorganism as disclosed herein is increased as compared to the expression or activity of said one or more genes or gene products in a non-variant or wild-type Rhodospirillum microorganism.

[0170] In some embodiments, the expression or activity of the Rru_A0247 gene encoding for the Lacl transcriptional regulator or the expression of the Lacl transcriptional regulator protein is increased in the genetic variant microorganism of the invention as compared to the expression or activity of said gene or gene product in a non-variant or wild-type microorganism. In some further embodiments, the genetic variant microorganism of the invention comprises increased protein levels of the Lacl transcriptional regulator as compared to a non-variant or wild-type microorganism.

[0171] In some embodiments, the expression or activity of the Rru_A0248 gene encoding for the inner-membrane translocator or the expression of the inner-membrane translocator protein is increased in the genetic variant microorganism of the invention as compared to the expression or activity of said gene or gene product in a non-variant or wild-type microorganism. In some further embodiments, the genetic variant microorganism of the invention comprises increased protein levels of the inner-membrane translocator protein as compared to a non-variant or wild-type microorganism.

[0172] In some embodiments, the expression or activity of the Rru_A0247 gene encoding for the Lacl transcriptional regulator or the expression of the Lacl transcriptional regulator protein is increased together with expression or activity of the Rru_A0248 gene encoding for the inner-membrane translocator or the expression of the inner-membrane translocator protein in the genetic variant microorganism of the invention as compared to the expression or activity of said genes or gene products in a non-variant or wild-type microorganism. In some further embodiments, the genetic variant microorganism of the invention comprises increased protein levels of the Lacl transcriptional regulator and the inner-membrane translocator protein as compared to a non-variant or wild-type microorganism.In some embodiments, the expression or activity of the Rru-A0249 gene encoding for the ABC transporter or the expression of the ABC transporter protein is increased in the genetic variant microorganism of the invention as compared to the expression or activity of said gene or gene product in a non-variant or wild-type microorganism. In some further embodiments, the genetic variant microorganism of the invention comprises increased protein levels of the ABC transporter protein as compared to a non-variant or wild-type microorganism.

[0173] In some embodiments, the expression or activity of the Rru_A0250 gene encoding for xylulokinase or the expression of the xylulokinase protein is increased in the genetic variant microorganism of the invention as compared to the expression or activity of said gene or gene product in a non-variant or wild-type microorganism. In some further embodiments, the genetic variant microorganism of the invention comprises increased protein levels of the xylulokinase protein as compared to a non-variant or wild-type microorganism.

[0174] In some embodiments, the expression or activity of the Rru_A0247 gene encoding for the Lacl transcriptional regulator or the expression of the Lacl transcriptional regulator protein is increased together with expression or activity of the Rru_A0248 gene encoding for the inner-membrane translocator or the expression of the inner-membrane translocator protein, the expression or activity of the Rru-A0249 gene encoding for the ABC transporter or the expression of the ABC transporter protein, and the expression or activity of the Rru_A0250 gene encoding for xylulokinase or the expression of the xylulokinase protein, in the genetic variant microorganism of the invention as compared to the expression or activity of said genes or gene products in a non-variant or wildtype microorganism. In some further embodiments, the genetic variant microorganism of the invention comprises increased protein levels of the Lacl transcriptional regulator, the inner-membrane translocator protein, the ABC transporter, and xylulokinase, as compared to a non-variant or wild-type microorganism.

[0175] In some embodiments, the expression or activity of the Rru_A0251 gene encoding for the transcriptional regulator AraC family or the expression of the transcriptional regulator AraC family is increased in the genetic variant microorganism of the invention as compared to the expression or activity of said gene or gene product in a non-variant or wild-type microorganism. In some further embodiments, the genetic variant microorganism of the invention comprises increased protein levels of the transcriptional regulator AraC family protein as compared to a non-variant or wild-type microorganism.In some embodiments, the expression or activity of the Rru_A0243 gene encoding for the tRNA / rRNA cytosine C5 methylase or the expression of the tRNA / rRNA cytosine C5 methylase is increased in the genetic variant microorganism of the invention as compared to the expression or activity of said gene or gene product in a non-variant or wild-type microorganism. In some further embodiments, the genetic variant microorganism of the invention comprises increased protein levels of the tRNA / rRNA cytosine C5 methylase protein as compared to a non-variant or wild-type microorganism.

[0176] In some embodiments, the expression or activity of the Rru_0241 gene encoding for the DNA methylase N-4 / N-6 or the expression of the DNA methylase N-4 / N-6 is increased in the genetic variant microorganism of the invention as compared to the expression or activity of said gene or gene product in a non-variant or wild-type microorganism. In some further embodiments, the genetic variant microorganism of the invention comprises increased protein levels of the the DNA methylase N-4 / N-6 protein as compared to a non-variant or wild-type microorganism.

[0177] Table 3. Overview of increased expression of proteins in some embodiments of the genetic variant microorganism of the invention.

[0178] Protein description Uniprot ID Locus tag Xylulokinase Q2RXU0 Rru_A0250

[0179] ABC transporter component Q2RXU1 Rru_A0249

[0180] Inner-membrane translocator Q2RXU2 Rru_A0248 Periplasmic binding protein / Laci transcriptional regulator Q2RXU3 Rru_A0247 Transcriptional regulator, AraC family Q2RXT9 Rru_A0251 tRNA / rRNA cytosine C5-methylase Q2RXU7 Rru_A0243

[0181] DNA methylase N-4 / N-6 Q2RXU9 Rru_A0241

[0182]

[0183] Any meaningful extent of increased expression and / or activity of a gene or gene product or protein in envisaged. Hence, the terms "increase", "increased", "upregulate", upregulated", "elevate", "elevate", "enhance", "enhanced", may in appropriate contexts, denote a statistically significant increase relative to a reference, in particular wherein the reference is represented by the expression and / or activity in a non-variant Rhodospirillum microorganism. For example, such increase may fall outside of error margins for the reference (as expressed, for example, by standard deviation or standard error, or by a predetermined multiple thereof, e.g. ±lxSD, ±2xSD, ±lxSE, ±2xSE). By means of illustration, the expression and / or activity of a particular gene or gene productor protein may be considered increased when it is increased by at least 10%, such as by at least 20% or by at least 30%, preferably by at least 40%, such as by at least 50% or by at least 60%, more preferably by at least 70%, such as by at least 80% or by at least 90% or more, as compared to the reference, up to and includes a 100% increase, or a 200% increase, or even more.

[0184] In some embodiments, the genetic variant microorganism is characterized in that the Lacl transcriptional regulator has diminished ability to bind to the xylitol assimilation gene cluster operator as compared to the Lacl transcriptional regulator of the non-variant microorganism. As corroborated in the experimental section, the Lacl transcriptional regulator of the genetic variant microorganism that was evaluated in the examples was found to have an altered protein function and impaired capacity to bind to the operator of the xylitol assimilation gene cluster, as compared to the Lacl transcriptional regulator of a non-variant microorganism.

[0185] As used herein, the terms "diminished", "diminish", "reduce", "reduced", "decease" or "decreased" may in appropriate contexts denote a statistically significant decrease relative to a reference, in particular wherein the reference is represented by in a non-variant Rhodospirillum microorganism. For example, such a decrease may fall outside of error margins for the referenced (as expressed, for example, by standard deviation or standard error, or by a predetermined multiple thereof, e.g. ±lxSD, ±2xSD, ±lxSE, ±2xSE). By means of illustration, the ability of a protein to bind to an operator may be considered diminished when it is reduced by at least 10%, such as by at least 20% or by at least 30%, preferably by at least 40%, such as by at least 50% or by at least 60%, more preferably by at least 70%, such as by at least 80% or by at least 90% or more, as compared to the reference, up to and includes a 100% decrease (i.e., no ability to bind to the operator as compared to the non-variant microorganism).

[0186] An aspect of the invention further provides a method of producing a genetic variant microorganism of the genus Rhodospirillum having increased glucose assimilation capacity, the method comprising the steps of:

[0187] a) generating a population of genetic variant microorganisms from a starting non-variant or wild-type Rhodospirillum microorganism; and

[0188] b) selecting from said population a genetic variant microorganism which exhibits said increased glucose assimilation capacity as compared to the starting microorganism, wherein the genetic variant microorganism has modified expression or activity of one or more genes or gene products of the xylitol assimilation gene cluster as compared to the starting microorganism, and wherein the genes of the xylitol assimilation gene cluster are selected from theRru_A0247 gene, the Rru_A0248 gene , the Rru_A0249 gene and the Rru_0250 gene, which are the genes encoding for the proteins selected from the Lacl transcriptional regulator, inner-membrane translocator, ABC transporter, and / or xylulokinase.

[0189] In some embodiments, the genetic variant microorganism is generated by introducing a genetic modification; in particular a mutation; more in particular a missense mutation; in the Rru_A0247 gene that encodes the Lacl transcriptional regulator and in the Rru_A0248 gene that encodes the inner-membrane translocator, and wherein the wild-type form of the Rru_A0247 gene comprises the nucleotide sequence as set forth in SEQ ID NO: 1 and the wild-type form of the Rru_A0248 gene comprises the nucleotide sequence as set forth in SEQ ID NO: 3.

[0190] In some embodiments, the genetic variant microorganism is produced by directed evolution, natural adaptation, natural selection, or genetic engineering of a wild-type, non-variant Rhodospirillum microorganism.

[0191] Also provided is a method to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation by introducing a genetic modification in one or more genes of the xylitol assimilation gene cluster. In some embodiments, said genetic modification is a mutation. In some further embodiments, said genetic modification is a mutation, in particular a missense mutation. In the methods disclosed herein, the genes of the xylitol assimilation gene cluster are selected from the genes encoding for the proteins selected form Lacl transcriptional regulator, inner-membrane translocator, ABC transporter and xylulokinase.

[0192] In some embodiments, the methods are provided to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation or to produce a genetic variant microorganism, by introducing a genetic modification, in particular a mutation, more particular a missense mutation, in the Rru_A0247 gene that encodes for the Lacl transcriptional regulator.

[0193] In some embodiments, the methods are provided to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation or to produce a genetic variant microorganism, by introducing a genetic modification, in particular a mutation, more particular a missense mutation, in the Rru_A0248 gene that encodes for the inner-membrane translocator.

[0194] In some embodiments, the methods are provided to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation or to produce a genetic variant microorganism, by introducing a genetic modification, in particular a mutation, more particular a missense mutation, in the Rru_A0249 gene that encodes for the ABC transporter.In some embodiments, the methods are provided to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation or to produce a genetic variant microorganism, by introducing a genetic modification, in particular a mutation, more particular a missense mutation, in the Rru_A0250 gene that encodes for the xylulokinase.

[0195] In some embodiments, the methods are provided to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation or to produce a genetic variant microorganism, by introducing a genetic modification, in particular a mutation, more particular a missense mutation, in the Rru_A0247 gene that encodes for the Lacl transcriptional regulator, and in one or more genes selected from the Rru_A0248 gene that encodes the inner-membrane translocator, the Rru_A0249 gene that encodes the ABC transporter and the Rru_A250 gene that encodes xylulokinase. In some further embodiments, methods are provided to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation or to produce a genetic variant microorganism, by introducing a genetic modification, in particular a mutation, more particular a missense mutation, in the Rru_A0247 gene that encodes for the Lacl transcriptional regulator, in the Rru_A0248 gene that encodes the inner-membrane translocator, and optionally in the Rru_A0249 gene that encodes the ABC transporter and in the Rru_A0250 gene that encodes xylulokinase.

[0196] In some embodiments, methods are disclosed to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation, or to produce a genetic variant microorganism, by introducing a mutation, in particular a missense mutation, in the Rru_A0247 gene that encodes the Lacl transcriptional regulator. In some embodiments, a method is disclosed to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation or to produce a genetic variant microorganism by introducing a mutation such the Rru_A0247 gene that encodes the Lacl transcriptional regulator comprises a polynucleotide sequence as defined in SEQ ID NO: 10. In some embodiments, methods are disclosed to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation or to produce a genetic variant microorganism, by introducing a mutation, in particular a missense mutation, in the Rru_A0248 gene that encodes the inner-membrane translocator. In some embodiments, a method is disclosed to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation or to produce a genetic variant microorganism, by introducing a mutation such the Rru_A0248 gene that encodes the inner-membrane translocator comprises a polynucleotide sequence as defined in SEQ ID NO: 12.In some further embodiments, methods are disclosed to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation, or to produce a genetic variant microorganism, by introducing a mutation, in particular a missense mutation, in the Rru_A0247 gene that encodes the Lacl transcriptional regulator and in the Rru_A0248 gene that encodes the inner-membrane translocator. In some embodiments, a method is disclosed to modify a microorganism of the genus Rhodospirillum to increase its glucose assimilation or to produce a genetic variant microorganism by introducing at least two mutations such the Rru_A0247 gene that encodes the Lacl transcriptional regulator comprises a polynucleotide sequence as defined in SEQ ID NO: 10 and the Rru_A0248 gene that encodes the inner-membrane translocator comprises a polynucleotide sequence as defined in SEQ ID NO: 12.

[0197] Genetic modification of a microorganism to increase its glucose assimilation can be done by any method known to induce genetic modifications in a microorganism. In some embodiments, the method includes direct genetic engineering of the microorganism. Direct genetic engineering techniques may be selected from recombinant DNA technology, genome editing using CRISPR, Transcription Activator-Like Effector Nucleases (TALENs), zinc finger Nucleases (ZFNs), or other molecular biology techniques. In some embodiments, the method includes adaptive evolution through prolonged exposure to specific environmental conditions, such as long-term exposure of the Rhodospirillum microorganism to glucose, leading to spontaneous mutations.

[0198] Another aspect provides the use of the genetic variant microorganism according to any of the embodiments disclosed herein for the production of amino acids, vitamins, proteins, biomass or an extract thereof, co-enzyme Q10, carotenoids, and / or bioethanol.

[0199] A further aspect provides a method for the production of amino acids, vitamins, proteins, biomass, and / or bioethanol, said method comprising culturing a genetic variant microorganism as disclosed herein in a substrate comprising carbohydrates, and in a culture medium, under conditions that are suitable for growth of the genetic variant microorganism and for production of amino acids, vitamins, proteins, biomass, and / or bioethanol, wherein said genetic variant microorganism produces amino acids, vitamins, proteins, biomass, and / or bioethanol. In particular embodiments, the substrate comprises sucrose, fructose, and / or glucose. In some further embodiments, the substrate comprises glucose. In some embodiments, the method can be performed in a bioreactor. The culture medium used for the culture of the microorganisms disclosed herein may be a usual medium that contains a carbon substrate, as well as other organic components if necessary. Carbonsubstrates for use in accordance with the invention include carbohydrates (including monosaccharides, disaccharides, trisaccharides, and polysaccharides). Examples of carbon substrates that can be used in accordance with the invention include, but are not limited to, starches (such as corn, oat, wheat, rye, rice, barley, millet, quinoa, potato, and the like); sugars (such as glucose, fructose, mannose, galactose, maltose, lactose, cellobiose, gentiobiose, melibiose, sucrose, trehalose, manitriose, rabinose, rhamnose, raffinose); starch hydrolysate; alcohols (such as glycerol or sorbitol); or organic acids (such as fumaric acid, citric acid, or succinic acid). The modified microorganisms of the present invention are preferably grown on mediums of glucose. As used herein "bioreactor" refers to an enclosure or partial enclosure in which cells, such as bacteria, are cultured, optionally in suspension. Bioreactors can be configured to flow culture media through the bioreactor throughout the time period during which the bacteria reproduce and increase in number. In some embodiments media can be infused into the bioreactor after inoculation but before the cells reach a desired density. In some embodiments, a bioreactor is filled with culture media at the beginning of a culture and no more culture media is infused after the culture is inoculated. In other words, the bacterial biomass or other products are cultured in aqueous medium for a period of time during which the bacteria reproduce and increase in number. Bioreactors typically allow for the control of culture conditions such as temperature, pH, oxygen tension, and carbon dioxide levels. For example, bioreactors are typically configurable, for example, using ports attached to tubing, to allow gaseous components, like oxygen or nitrogen, to be bubbled through a liquid culture.

[0200] The method for the production of amino acids, vitamins, proteins, biomass, and / or bioethanol according to the invention is preferably executed by using a bioreactor suitable for use in an industrial setting. A bioreactor suitable for use in an industrial setting adheres to standard requirements in the field of industrial fermentation of microorganism.

[0201] As used herein, the term "biomass" refers to material produced by growth and / or propagation of cells, such as bacteria. Biomass may contain cells and / or intracellular contents as wells as extracellular material, which includes but is not limited to, compounds secreted by a cell.

[0202] Further disclosed is biomass obtainable by the method for the production of biomass as disclosed herein and according to any of its disclosed embodiments;

[0203] The biomass produced or obtained by the genetic variation microorganisms of the invention or by any of the methods disclosed herein can be used to feed or provide nutrition to one or more organisms. The agricultural industry typically uses similar feed in organisms such as fish,crustaceans, molluscs, poultry, pigs, and cattle. Therefore, the present invention also relates to the use of the biomass produced or obtained by any of the methods disclosed herein to feed or provide nutrition to, for example, fish, crustaceans, molluscs, poultry, pigs, and cattle.

[0204] Also provided is a feed or nutritional product comprising biomass, amino acids, vitamins and / or proteins produced by the genetic variant microorganism according to any of its disclosed embodiments. Also provided is a feed or nutritional product comprising biomass, amino acids, vitamins and / or proteins produced by any of the methods disclosed herein. In some embodiments, said feed or nutritional product is a feed or nutritional product to feed or provide nutrition to, for example, fish, crustaceans, molluscs, poultry, pigs, and cattle.

[0205] Further provided is a method for identifying, in a sample, the presence or prior use of a genetic variant microorganism as disclosed, the method comprising

[0206] - analysing a nucleic acid from the sample to detect:

[0207] i) at least one mutation in the Rru_A0247 gene encoding for the Lacl transcriptional regulator, optionally wherein the wild-type form of said gene comprises the nucleotide sequence as set forth in SEQ ID NO: 1;

[0208] ii) at least one mutation in the Rru_A0248 gene encoding for the inner-membrane translocator, optionally wherein the wild-type form of said gene comprises the nucleotide sequence as set forth in SEQ ID NO: 3; and

[0209] - identifying the presence or prior use of the genetic variant microorganism in the sample if said mutations are detected.

[0210] In some embodiments, in step i) of said method the nucleic acid is analysed for the presence of the nucleotide sequence as set forth in SEQ ID No: 9, and in step ii) the nucleic acid is analysed for the presence of the nucleotide sequence as set forth in SEQ ID NO: 11.

[0211] In some embodiments, the method may further comprise analysing the nucleic acid from the sample to detect any mutation that is disclosed herein.

[0212] Another aspect provides a kit for identifying, in a sample, the presence or prior use of a genetic variant microorganism as disclosed herein, the kit comprising:

[0213] - at least one reagent capable of detecting a mutation in the Rru_A0247 gene encoding for the Lacl transcriptional regulator, optionally wherein the wild-type form is said gene comprises the nucleotide sequence as set forth in SEQ ID NO: 1 and- at least one reagent capable of detecting a mutation in the Rru_A0248 gene encoding for the inner-membrane translocator, optionally wherein the wild-type form of said gene comprises the nucleotide sequence as set forth in SEQ. ID NO: 3.

[0214] In some embodiments, the kit may further comprise one or more reagents capable of one or more mutations as described herein.

[0215] In some embodiments, the sample is a food sample, such as a sample derived from a food product. In some further embodiments, the food product is a nutritional product to feed or provide nutrition to humans, fish, crustaceans, molluscs, poultry, pigs, and / or cattle.

[0216] The herein disclosed aspects and embodiments of the invention are further supported by the following non-limiting examples.

[0217] EXAMPLES

[0218] Materials and methods

[0219] Bacterial strains, medium composition, and culture conditions

[0220] Bacterial strain Rs. rubrum SIH (ATCC 25903) and the glucose-acclimated strain, named MG strain and as deposited under accession no. LMG P-34001, were cultivated under photoheterotrophic conditions. The glucose-acclimated strain (referred herein as MG strain) is a Rs. Rubrum strain as deposited under the Budapest Treaty at the Belgian Coordinated Collections of Micro-organisms (BCCM) on March 13, 2025 under Accession No. LMG P-34001.

[0221] For small scale cultivation experiments, the culture medium's carbon source consisted of sucrose, glucose, fructose or a combination of fructose and glucose, all at a carbon equivalent concentration of 120 mM. Nitrogen was supplied as ammonium chloride (35 mM), and biotin (0.06 pM) was added as a vitamin source. Cultures were initiated under photoheterotrophic conditions in 50 mL serum bottles with a working volume of 40 mL. For sterilisation, the medium containing glucose or fructose were previously filtered on 0.22 pm whereas the sucrose-containing medium was previously autoclaved to partially hydrolyse sucrose into fructose and glucose. Stock cultures were grown in a supplemented malate-ammonium medium, called SMN medium, which is enriched in yeast extract and peptone. After inoculation, oxygen was removed from the gas phase by purging with sterile nitrogen and the bottles were sealed to create an anaerobic environment for bacterial growth.Cultures were incubated at 30°C with agitation at 170 rpm. Illumination was provided at a light intensity of 177 pmol photons m“2s-1using halogen lamps (10 W, 100 Im; 2650 K; Sencys). The illumination intensity was adjusted to correct for detector bias (Apogee Quantum Flux MQ-200) using an in-house developed app (https: / / github.com / damien-dumont / LightConverter). Bacterial growth was monitored daily by measuring OD680. To determine biomass content for Rs. rubrum, OD680 were converted to dry cell weight (DCW, mg / ml) using a correlation curve.

[0222] Photobioreactor (PBR) inocula were prepared in lOOmL serum flasks in SMN medium or in a glucose-containing medium for the wild-type and the glucose-acclimated strains, respectively. After inoculation, oxygen was removed from the gas phase by purging with sterile nitrogen and the bottles were sealed to create an anaerobic environment for bacterial growth. For the sequential batch (PBR) experiments, the wild-type and MG strains of Rs. rubrum were cultivated in a 2L-glass vessel (Biostat®, Sartorius AG, Germany) in a molasses-containing medium (6g / L) issued from ISCAL®, a sugar factory based in Fontenoy (Belgium) and supplemented with ammonium chloride (35mM). The medium was sterilised through autoclaving procedure. Following sterilisation, NaHCO3 (20mM), biotin (0.06pM), trace elements and invertase at 16U / L of medium (E1103, Merck®, 2400U / mL) were added to the medium. Invertase concentration was optimised to yield the hydrolysis of 1 mmol of sucrose into fructose and glucose in 1 hour. Starting biomass concentration was set at ~0.24g / L corresponding to an OD680 of 0.4 as determined by the calibration curve. The cultures were illuminated continuously with a 20W light source (201 lumens, 2700K, Sencys®) surrounding the PBR, providing an intensity of ±400 pmol photons m“2s-1(LI-205A, Li-Cor BioSciences) at the centre of the PBR. Agitation was set to 100 rpm. Light intensity was adjusted for detector bias using a custom app (https: / / github.com / damien-dumont / LightConverter), with halogen lamp emission spectra. To conduct sequential batch, 90% of the culture was replaced by fresh medium as soon as a stationary phase (i.e. 2 consecutive points with similar optical density at 680nm) was observed. Axenicity of the photobioreactors was checked after each sequential batch through plating of the culture on SMN agar plates.

[0223]

[0224] of the consum

[0225] Biomass was eliminated by centrifugation at 10,000 g for 10 minutes. Sucrose, fructose and glucose were subsequently analysed in the culture supernatant using liquid chromatography-mass spectrometry. To separate sugars, an HPLC system (Sciex, ExionLCTM Series UHPLC, Shimadzu model) equipped with an XBridge BEH Amide column (130 A, 2.1 x 150 mm, 5 pm) (WatersCorporation, 186006590) was used. Sugar separation was performed in isocratic mode, with a flow rate of 0.6 ml / min at a temperature of 80°C. The separation was finalised in 7 minutes with an injection volume of lpl. The mobile phase was composed of 15% (v / v) acetonitrile and 5 mM ammonium formate at pH 7. Eluting components were analysed online with a ZenoTOF mass spectrometer (ZenoTOF 7600 system, Sciex). The detection range was between 20 and 400 m / z. Ionisation was conducted in negative mode at an ion source temperature of 250°C, a capillary voltage of -4500 V, a declustering potential of -80 V, and a collision energy of -5 V.

[0226] The quantification of sugars was performed using Sciex OS software (version 2.1.6.59781), applying a targeted identification and quantitation approach. Glucose, fructose, and sucrose were quantified by integrating their respective peaks in the XIC at 179.056 Da for glucose and fructose and at 341.109 Da for sucrose in MS spectra. These compounds were observed at retention times of 1.867 min (glucose), 1.483 min (fructose), and 3.447 min (sucrose). Quantifications were carried out using a calibration curve based on standard solutions.

[0227] Comparative analyses by proteomic analyses

[0228] Sample preparation and MS data acquisition were carried out as previously described. Comparative analyses were conducted using data-independent (DIA, SWATH) acquisition modes. For SWATH analyses, 100 incremental steps were set up as windows of variable m / z values within a 400-1250 m / z mass range. Each window was analysed for 50 ms, resulting in a 5-second duty cycle per complete cycle. For each peptide, the ion chromatogram of the top six fragments was extracted and integrated to determine the area under the curve. A DDA acquisition mode was employed to create a MS / MS library using ProteinPilot software (version 4.5, AB Sciex, USA). Both wildtype and MG strains samples obtained from culture performed with carbohydrate as carbon sources were included for the spectral library creation.

[0229] Skyline software was employed for processing SWATH data and quantifying proteins identified with a false discovery rate (FDR) below 0.95%, as determined by ProteinPilot. Only proteins quantified by two or more peptides, exhibiting a fold change greater than 1.5 or less than 0.66, and with a p-value below 0.05 were further considered.

[0230] 16S sequencing and whole-genome analysis

[0231] For 16S sequencing, MG strain samples were collected at the end of the bacterial growth. Genomic DNA was extracted from 1 mL of bacterial culture using the DNeasy® PowerSoil® Pro Kit (Quiagen, 47014), following the manufacturer's instructions. DNA concentration was determined using the QuantiFluor® One dsDNA Dye (Promega, E489A). To verify the culture axenicity, a 16S sequencingwas performed using the 16S Barcoding Kit 24 V14 (Oxford Nanopore Technologies, SQK-16S114.24). The entire "'1,500 bp 16S rRNA gene was amplified by PCR using specific barcoded 16S primers and 10 ng of genomic DNA. The barcoded samples were then quantified, pooled and cleaned before loading them on a MinlON and GridlON flow cell (FLO-MIN114.8). Downstream analyses were performed using the EPI2ME Labs 16S workflow to classify the 16S amplicons and identify organisms present in the samples using the following parameters: classification method: minimap2, database: NCBI-16S-18S, taxonomic rank: genus, minimum reads length: 1200 pb, maximum reads length: 1800 pb, minimum score quality: 9, minimum percentage identity: 95, minimum reference coverage: 90.

[0232] In order to identify potential mutations in the genome of the MG strain, whole-genome sequencing analysis was conducted by Eurofins Genomics (eurofinsgenomics.com). DNA was extracted as described above on samples of the MG strain and on the WT strain. Whole-genome sequencing was performed using the Illumina method, by generating reads with a length of 2 x 150 base pairs. Alignment was conducted against the reference genome of Rhodospirillum rubrum ATCC 11170 (Gen Bank ID: NC_007643.1). After sequencing, the WT strain and MG strain genomes were aligned to detect potential mutations.

[0233] Results

[0234] Long-term glucose exposure induced an acclimation in Rhodospirillum rubrum SIH

[0235] As it has been shown that the xylitol assimilation gene cluster is involved in glucose assimilation by Rs. rubrum, we aimed to determine whether glucose assimilation capacity could be triggered by xylitol assimilation. We first cultivated wild-type Rs. rubrum in a glucose-containing medium (Figure 1). As typically observed, Rs. rubrum did not grow in this medium. After approximately 70 hours, xylitol was added. As soon as xylitol was introduced into the culture medium, glucose consumption by Rs. rubrum began and continued even after the complete assimilation of xylitol (Figure 1). However, the glucose assimilation rate was significantly lower— approximately ten times slower— than that observed in the acclimated strain. This suggests that while the expression of proteins involved in xylitol assimilation is essential, it is not sufficient to achieve the assimilation rate observed in the acclimated strain, likely due to the mutations found in the xylitol assimilation gene cluster in the acclimated strain.

[0236] We previously showed that Rs. rubrum, although described in the literature as unable to assimilate glucose, was able to grow using this carbon source when this carbon source was provided withfructose (Gilson et al., in preparation). However, the productivity was more than 5 times lower during the glucose assimilation phase that followed the fructose assimilation phase (0.07 g / L / day and 0.45 g / L / day, respectively). In order to select for glucose assimilation capacity, we exposed Rs. rubrum to a medium containing only glucose as carbon source for two months. After two months, a purple biomass was obtained at a concentration of 3.12 ± 0.32 mg / ml DCW, as determined by OD measurement at 680nm. An inoculum from this culture was transferred to fresh media containing either glucose, fructose or a mixture of glucose and fructose as carbon sources, each at 120 mM carbon equivalent. Cultures of the wild-type strain of Rs. rubrum were started in parallel in the same conditions.

[0237] Results showed that the acclimated strain, named MG strain for Molasses-Glucose strain, grew up reaching a maximum OD680nm of 5.06 ± 0.32 (3.04 ± 0.19 mg / ml DCW) in the presence of fructose, 4.67 ± 0.24 (2.8±0.14 mg / ml DCW) in the presence of glucose and 4.7 ± 0.12 (2.82 ± 0.07 mg / ml DCW) in the presence of glucose and fructose (Figure 2B). In contrast, the wild-type strain grew up reaching a maximum OD680nm of 5.42 ± 0.34 (3.25 ± 0.2 mg / ml DCW) in the presence of fructose and 2.84 ± 0.09 (1.7 ± 0.05 mg / ml DCW) in the presence of glucose and fructose (Figure 2A). The growth observed for the wild-type strain in the presence of glucose only was very slow and reached an OD680nm of 0.55 ± 0.07 (0.33 ± 0.04 mg / ml DCW) in 7.3 days. The productivity of the MG strain in presence of glucose or fructose were similar, being at 0.72 g / L.day and 0.78 g / L.day, respectively. At the end of the growth, to control that the culture was free of any contamination that might explain the high glucose assimilation rate, 16S sequencing and a MS method previously developed in our laboratory (Gilson et al., in preparation) were conducted to confirm microbial composition. Analyses showed that the culture was free of any contamination and only composed of Rs. rubrum, which confirms our strain acquired, through long term exposure to glucose, the capacity to grow in the presence of this carbon source only (data not shown).

[0238] To test the reversibility of the MG strain's ability to assimilate glucose, the latter was grown in a medium containing succinate as the sole carbon source for 3 consecutive batches (+ / - 15 generations). At the end of each batch, the MG strain was cultivated again in a glucose-containing medium. No changes in growth rate was observed after cultivation in succinate, showing a productivity of 0.9 g / L / day, 1.1 g / L / day and 1 g / L / day after the first, the second and the third batch in succinate, respectively (data not shown). These results suggest a stable modification of Rs. rubrum in the MG strain, different to what was observed previously by our group for an acetate-acclimated strain arising from genomic island duplication.In a previous study (Gilson et al., in preparation), we showed that fructose and glucose were sequentially assimilated, with fructose being first assimilated in the WT strain. To test whether fructose also constitutes a preferred carbon source for the MG strain, we cultivated the latter in a medium containing sucrose that was previously autoclaved, leading to the partial hydrolysis of sucrose into glucose and fructose. Results showed that, despite an identical initial concentration, fructose and glucose were sequentially assimilated (Figure 3). Fructose was fully assimilated after 23 hours while glucose was fully assimilated only after 47 hours of cultivation, showing that, even in the MG strain, fructose is preferentially assimilated over glucose.

[0239] Rs. Rubrum SIH glucose-acclimated strain characterisation

[0240] To characterise the glucose-acclimated strain and identify the origine of the gain of function, we first performed a whole-genome sequencing analysis using the Illumina method. The sequencing results revealed 12 missense mutations in the MG strain genome compared with the WT strain (Table 4). Two of these missense mutations are located in two genes from a gene cluster involved in the transport and catabolism of xylitol in Rs. rubrum. The first, found at position 308176 of the genome, is located within the gene Rru_A0247 and this mutation leads to an amino-acid switch from a glutamine to a proline in position 43 of the protein. The second mutation, found at position 308419 of the genome, is located within gene Rru_A0248 and leads to an amino-acid switch from a lysine to a glutamic acid in position 320 of the protein.

[0241] We completed the characterisation of the MG strain with a proteomic approach to compare the proteome of the MG strain to the proteome of the WT strain, both grown in glucose-containing medium. Sampling time is indicated by a black arrow on figure IB for the MG strain. Our proteomic analysis revealed a higher abundance of seven proteins from a gene cluster in the glucose-acclimated strain compared to the wild-type strain (Table 5). Interestingly, four proteins from this gene cluster are involved in the transport and catabolism of xylitol in Rs. rubrum and two of these are encoded in genes where mutations were detected (Rru_A0247 and Rru_A0248). Indeed, the ABC transporter component (Rru_A0249, FC 29.85), the periplasmic binding protein / LacI transcriptional regulator (Rru_A0247, FC 16.65) and the inner-membrane translocator (Rru_A0248, FC 9.12) are all three described on KEGG as being involved in xylitol transport in Rs. rubrum. Xylulokinase (Rru_A0250, FC 43.52) is involved in the first steps of xylitol assimilation in Rs. rubrum, by phosphorylating D-xylulose to D-xylulose-5P. The genes coding for these 4 proteins are positioned consecutively within the genome (Figure 4A). It is important to mention that such fold changes are very high and represent a rather absent / present variation for these proteins.Table 4. Missense mutations observed in the MG strain genome in comparison with the WT strain. Missense mutations observed in the cluster of genes involved in xylitol metabolism are highlighted in greyscale.

[0242] Position in Reference Allele Total Allele Gene ID Protein description the genome base / depth(a|Depth(b|frequency

[0243] observed (%)M

[0244] base

[0245] 9292 G / C 57 410 13.90 Rru_A0008 Hypothetical protein 12786 T / G 66 388 17.01 Rru_A0011 ABC transporter protein 308176 T / G 61 419 14.56 Rru_A0247 Periplasmic binding protein /

[0246] Lacl transcriptional regulator 308419 T / C 258 382 67.54 Rru_A0248 Inner-membrane translocator 533622 T / G 53 273 19.41 Rru_A0453 CRISPR-associated endonuclease Csnl family protein

[0247] 1628057 A / C 39 175 22.29 / Non-coding region 2113937 C / A 233 359 64.90 Rru_A1817 TPR repeat-containing protein 2511970 T / G 64 305 20.98 Rru_A2162 Phosphohistidine phosphatase SixA

[0248] 3008470 T / G 45 257 17.51 Rru_A2588 Hypothetical protein 3143387 A / C 54 357 15.13 Rru_A2718 DEAD / DEAH box helicase 3737799 A / C 41 294 13.95 Rru_A3241 Chemotaxis sensory transducer

[0249] 3737802 T / G 36 292 12.33 Rru_A3241 Chemotaxis sensory transducer

[0250]

[0251] (a) Allele depth is described as the number of reads supporting each observed allele at a specific genomic site.

[0252] (b) Total depth refers to the total number of reads covering the analysed DNA site.

[0253] (c) Allele freguency is calculated as the ratio of allele depth to total depth.Table 5. Differential protein abundance in the MG strain.

[0254] Uniprot acc. Locus tag Glucose-acdimated strain / No. of description

[0255] no. WT strain identified

[0256] Rvalue Protein fold peptides(b|

[0257] change<al

[0258] Q2RXT9 Rru_A0251 2.83E-03 3.77 5 Transcriptional regulator, AraC family

[0259] Q2RXU0 Rru_A0250 2.13E-05 43.52 11 Xylulokinase

[0260] Q2RXU1 Rru_A0249 7.01E-08 29.85 4 ABC transporter component Q2RXU2 Rru_A0248 3.85E-04 9.12 2 Inner-membrane translocator Q2RXU3 Rru_A0247 2.61E-04 16.65 17 Periplasmic binding protein /

[0261] Lacl transcriptional regulator Q2RXU7 Rru_A0243 1.26E-02 2.13 4 tRNA / rRNA cytosine-C5- methylase

[0262] Q2RXU9 Rru_A0241 5.11E-08 6.97 2 DNA methylase N-4 / N-6

[0263]

[0264] (a) The protein fold change is defined as the ratio of the abundance of a protein under two different conditions.

[0265] (b) The number of identified peptides used for quantitative analysis are with a higher confidence than 95%.

[0266] Members of the Lacl family are transcription factors (TFs) that are well-known regulators of sugar metabolism in bacteria. By sensing the presence of various sugars, this family of TFs controls the expression of genes involved in sugar metabolism. Most of these TFs act as transcription repressors by binding to a DNA operator upstream of the gene cluster, preventing RNA polymerase from initiating transcription. Lacl family members are also known as regulators of their own operon. It is thus likely that, in the WT strain, the Lacl family member protein encoded by the Rru_A0247 gene (the periplasmic binding protein / LacI transcriptional regulator) regulates the gene cluster involved in xylitol assimilation. It acts as a transcriptional repressor by binding to a DNA region upstream of the gene cluster. In the MG strain, the mutation observed in the Rru_A0247 gene may have altered the protein function and impairing its capacity to bind to DNA. The genes involved in xylitol assimilation would then be constitutively expressed (Figure 4B). The structural similarity between xylitol and glucose may explain the ability of proteins involved in xylitol transport and phosphorylation to equivalently process glucose.

[0267] Lab demonstration and bioindustrial applications

[0268] In order to further characterise the MG strain and its potential for bioindustrial application, we decided to investigate its capacity to grow in the presence of molasses, a sucrose-rich sugar factory by product. The investigation of the molasses assimilation by the MG strain is of major interest as molasses represents an abundant (70 million tons) by-products in the world that is nowadaysmainly valorised through the production of bioethanol or as a feed ingredient. Therefore, the production of protein-rich Rs. rubrum biomass based on molasses would represent an up-cycling, converting sucrose in protein and health-promoting components such carotenoids, vitamins and Co-enzyme Q10. To study molasses utilisation by Rs. rubrum, we cultivated both the WT strain and the MG strain in the presence of a medium containing molasses (6 g / L) under sequential batch. Both strains were cultivated during two batches in the presence of molasses. As shown on Figure 4, we observe a decrease in sucrose concentration attesting that, considering Rs. rubrum is not capable to hydrolyse sucrose, invertase is active in the molasses-containing medium and that no inhibitory compounds are present in this co-product. As already observed during flask experiments, a biphasic growth is observed for the WT strain whereas no or minor biphasic growth is observed for the MG strain. Moreover, confirming flask experiments, sequential assimilation of fructose and glucose is observed for both strains suggesting that fructose constitutes the easiest assimilable carbon source for Rs. rubrum even if for the glucose-acclimated strain. Moreover, as shown by the monitoring of glucose concentration in the culture medium, an accumulation of glucose is observed in the supernatant of the WT strain whereas only minor glucose accumulation is observed in the presence of the glucose acclimated strain further attesting that the glucose acclimated strain is more efficient than the wild-type strain to assimilate this carbon source. As expected, the computed productivity of the MG strain is significantly almost twice higher (WT strain: 0.174 ± 0.008 g / L.D; MG strain: 0.285 ± 0.022 g / L.D ; p-value <0.05) than the productivity of the wild-type strain further attesting its interest for bio-industrial applications.

[0269] DEPOSIT OF BIOLOGICAL MATERIAL

[0270] Table 6 summarizes the requisite indications relating to this deposited microorganism.

[0271] Table 6

[0272] Accession number given by LMG P-34001

[0273] depositary institution

[0274] Identification reference given SIH MG

[0275] by the depositor

[0276] Name of depositary institution Belgian Coordinated Collections of Micro-organisms (BCCM)

[0277] Laboratorium voor Microbiologie - Bacterienverzameling (LMG) Address of depositary Universiteit Gent

[0278] institution K.L. Ledeganckstraat 35

[0279] 9000 Gent

[0280] Belgium

[0281] Date of deposit 13 / 03 / 2025

[0282] Depositor University of Mons

[0283] Address of depositor Place du Parc 20

[0284] 7000 Mons

[0285]

[0286] Belgium

Claims

1. CLAIMS1. A genetic variant microorganism of the genus Rhodospirillum, wherein:- the expression or activity of one or more genes or gene products of the xylitol assimilation gene cluster is modified as compared to the expression or activity of said one or more genes or gene products in a non-variant or wild-type Rhodospirillum microorganism,- the genes of the xylitol assimilation gene cluster are selected from the Rru_A0247 gene encoding for the Lacl transcriptional regulator, the Rru_A0248 gene encoding for the inner-membrane translocator, the Rru_A0249 gene encoding for the ABC transporter and the Rru_A0250 gene encoding for xylulokinase; and- glucose assimilation in the genetic variant microorganism is increased as compared to the non-variant or wild-type Rhodospirillum microorganism.

2. The genetic variant microorganism of claim 1, wherein the microorganism comprises a genetic modification; in particular a mutation; more in particular a missense mutation; in one or more genes of the xylitol assimilation gene cluster as compared to the non-variant or wild-type Rhodospirillum microorganism.

3. The genetic variant microorganism of claim 1 or 2, wherein the microorganism comprises a genetic modification; in particular a mutation; more in particular a missense mutation; in the Rru_A0247 gene encoding for the Lacl transcriptional regulator, and wherein the wild-type form of said gene comprises the nucleotide sequence as set forth in SEQ ID NO: 1.

4. The genetic variant microorganism of any one of claims 1 to 3, wherein the microorganism comprises a genetic modification; in particular a mutation; more in particular a missense mutation; in the Rru_A0248 gene encoding for the inner-membrane translocator, and wherein the wild-type form of said gene comprises the nucleotide sequence as set forth in SEQ ID NO:

3. .

5. The genetic variant microorganism of claim 3 or 4, wherein the microorganism comprises a genetic modification; in particular a mutation; more in particular a missense mutation; in the Rru_0247 gene encoding for the Lacl transcriptional regulator and in the Rru_A0248 gene encoding for the inner-membrane translocator.

6. The genetic variant microorganism of any one of claims 1 to 5, wherein the expression or activity of the Rru_A0247 gene encoding for the Lacl transcriptional regulator or of the gene product Lacl transcriptional regulator is increased in the genetic variant microorganism as compared to theexpression or activity of said gene or gene product in the non-variant or wild-type Rhodospirillum microorganism.

7. The genetic variant microorganism of any one of claims 1 to 6, wherein the Lacl transcriptional regulator of the genetic variant microorganism has diminished ability to bind to the xylitol assimilation gene cluster operator as compared to the Lacl transcriptional regulator of the nonvariant or wild-type Rhodospirillum microorganism.

8. The genetic variant microorganism of any one of claims 1 to 7 , wherein the Lacl transcriptional regulator protein in the genetic variant microorganism comprises an amino acid substitution at position 43 as compared to the Lacl transcriptional regulator protein (SEQ ID NO: 2) in the nonvariant or wild-type Rhodospirillum microorganism; in particular wherein the genetic variant microorganism comprises a single amino acid substitution; more in particular a proline, at position 43 of SEQ ID NO: 2.

9. The genetic variant microorganism of any one of claims 1 to 8, wherein the expression or activity of the Rru_A0248 gene encoding for the inner-membrane translocator protein or of the gene product inner-membrane translocator protein is increased in the genetic variant microorganism as compared to the expression or activity of said gene or gene product in the non-variant or wild-type Rhodospirillum microorganism.

10. The genetic variant microorganism of any one of claims 1 to 9, wherein the expression or activity of the Rru_A0247 gene encoding for the Lacl transcriptional regulator and of the Rru_A0248 gene encoding for the inner-membrane translocator protein, or of the gene products Lacl transcriptional regulator and inner-membrane translocator protein is increased in the genetic variant microorganism as compared to the expression or activity of said genes or gene products in the non-variant or wild-type Rhodospirillum microorganism.

11. The genetic variant microorganism of any one of claims 1 to 10, wherein the inner-membrane translocator protein in the genetic variant microorganism comprises an amino acid substitution at position 320 as compared to the inner-membrane translocator protein (SEQ ID NO: 4) in the non-variant or wild-type Rhodospirillum microorganism; in particular wherein the genetic variant microorganism comprises a single amino acid substitution; more in particular a glutamic acid, at position 320 of SEQ ID NO: 4.

12. The genetic variant microorganism of any one of claims 1 to 11, wherein the expression or activity of the gene products ABC transporter and xylulokinase are increased as compared to theexpression or activity of said gene products in the non-variant or wild-type Rhodospirillum microorganism.

13. The genetic variant microorganism of any one of claims 1 to 12, wherein the genetic variant microorganism comprises:- a mutation; more in particular a missense mutation; in the Rru_A0247 gene encoding for the Lacl transcriptional regulator;- a mutation; more in particular a missense mutation; in the Rru_A0248 gene encoding for the inner-membrane translocator;- increased expression of the gene products Lacl transcriptional regulator, the inner-membrane translocator, the ABC transporter and xylulokinase, as compared to the expression of said gene products in the non-variant or wild-type Rhodospirillum microorganism.

14. The genetic variant microorganism of any one of claims 1 to 13, wherein the genetic variant microorganism is a Rhodospirillum rubrum species.

15. The genetic variant microorganism of any one of claims 1 to 14, wherein the genetic variant microorganism is a Rhodospirillum rubrum strain as deposited under the Budapest Treaty at the Belgian Coordinated Collections of Micro-organisms (BCCM) on March 13, 2025 under Accession no. LMG P-34001 or a functional mutant thereof.

16. A microorganism that is a Rhodospirillum rubrum strain as deposited under the Budapest Treaty at the Belgian Coordinated Collections of Micro-organisms (BCCM) on March 13, 2025 under Accession no. LMG P-34001 or a functional mutant thereof.

17. A method of producing a genetic variant microorganism of the genus Rhodospirillum having increased glucose assimilation capacity, the method comprising the steps of:a) generating a population of genetic variant microorganisms from a starting non-variant or wild-type Rhodospirillum microorganism; andb) selecting from said population a genetic variant microorganism which exhibits said increased glucose assimilation capacity as compared to the starting microorganism, wherein the genetic variant microorganism has modified expression or activity of one or more genes or gene products of the xylitol assimilation gene cluster as compared to the starting microorganism, and wherein the genes of the xylitol assimilation gene cluster are selected from the Rru_A0247 gene, the Rru_A0248 gene , the Rru_A0249 gene and the Rru_0250 gene, which are thegenes encoding for the proteins selected from the Lacl transcriptional regulator, inner-membrane translocator, ABC transporter, and / or xylulokinase.

18. The method of claim 17, wherein the genetic variant microorganism is generated by introducing a genetic modification; in particular a mutation; more in particular a missense mutation; in the Rru_A0247 gene that encodes the Lacl transcriptional regulator and in the Rru_A0248 gene that encodes the inner-membrane translocator, and wherein the wild-type form of the Rru_A0247 gene comprises the nucleotide sequence as set forth in SEQ ID NO: 1 and the wild-type form of the Rru_A0248 gene comprises the nucleotide sequence as set forth in SEQ ID NO: 3.

19. The method of claim 17 or 18, wherein the genetic variant microorganism is produced by directed evolution, natural adaptation, natural selection, or genetic engineeringof a wild-type, nonvariant Rhodospirillum microorganism.

20. Use of the genetic variant microorganism of any one of claims 1 to 16 for the production of amino acids, vitamins, proteins, biomass or any extract of the biomass, co-enzyme Q10, carotenoids, and / or bioethanol.

21. A method for the production of amino acids, vitamins, proteins, biomass or any extract of the biomass, carotenoids, co-enzyme Q10, and / or bioethanol, comprising culturing the genetic variant microorganism of any one of claims 1 to 16 in a substrate comprising carbohydrates, and in a culture medium, under conditions that are suitable for growth of the genetic variant microorganism and for production of amino acids, vitamins, proteins, biomass or any extract of the biomass, carotenoids, co-enzyme Q10, and / or bioethanol, wherein said genetic variant microorganism produces amino acids, vitamins, proteins, biomass or any extract of the biomass, carotenoids, coenzyme Q10, and / or bioethanol; in particular wherein the substrate comprises sucrose, fructose and / or glucose; more in particular wherein the substrate comprises glucose.

22. A feed or nutritional product comprising biomass, amino acids, vitamins, and / or proteins produced by the genetic variant microorganism of any one of claims 1 to 16.

23. A method for identifying, in a sample, the presence or prior use of a genetic variant microorganism according to any of the claims 1 to 16, the method comprising- analysing a nucleic acid from the sample to detect:i) at least one mutation in the Rru_A0247 gene encoding for the Lacl transcriptional regulator, optionally wherein the wild-type form of said gene comprises the nucleotide sequence as set forth in SEQ ID NO: 1;ii) at least one mutation in the Rru_A0248 gene encoding for the inner-membrane translocator, optionally wherein the wild-type form of said gene comprises the nucleotide sequence as set forth in SEQ ID NO: 3; and- identifying the presence or prior use of the genetic variant microorganism in the sample if said mutations are detected.

24. The method of claim 23, wherein in step i) the nucleic acid is analysed for the presence of the nucleotide sequence as set forth in SEQ ID No: 9, and in step ii) the nucleic acid is analysed for the presence of the nucleotide sequence as set forth in SEQ ID NO: 11.

25. A kit for identifying, in a sample, the presence or prior use of a genetic variant microorganism according to any of the claims 1 to 16, the kit comprising:- at least one reagent capable of detecting a mutation in the Rru_A0247 gene encoding for the Lacl transcriptional regulator, optionally wherein the wild-type form is said gene comprises the nucleotide sequence as set forth in SEQ ID NO: 1 and- at least one reagent capable of detecting a mutation in the Rru_A0248 gene encoding for the inner-membrane translocator, optionally wherein the wild-type form of said gene comprises the nucleotide sequence as set forth in SEQ ID NO: 3.

26. The method of claim 23 or 24, or the kit of claim 25 wherein the sample is a food sample.

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