Biocatalytic process for the production of aroma chemicals

Abstract

The present invention relates to a biocatalytic process for the production of aroma chemicals by carboligation using a transketolase (EC 2.2.1.1) as shown for transketolase from Geobacillus stearothermophilus and several sequence variants to catalyse the conversion of a donor molecule selected from 2-oxobutanoic acid and 3-methyl-2-oxopentanoic acid and an acceptor molecule selected from propanal and 2-methylbutanal, two identical or different donor molecules, or two identical or different acceptor molecules, thereby obtaining a coupling product in the presence of coenzyme thiamine diphosphate, the products being 3-hydroxy-5-methyl-heptan-4-one, 4-hydroxy-5-methyl-heptan-3-one, 5-hydroxy-3,6-dimethyl-octan-4-one and 4-hydroxy-hexan-3-one as precursor for filbertone.

Description

[0001] BIOCATALYTIC PROCESS FOR THE PRODUCTION OF AROMA CHEMICALS FIELD OF THE INVENTION The present invention relates to a biocatalytic process for the production of aroma chemicals. More particularly, the process comprises a transaldolase or transketolase catalyzed conversion of a donor molecule and an acceptor molecule, two identical or different donor molecules, or two identical or different acceptor molecules, thereby obtaining a coupling product. The present invention also provides an aroma composition comprising said coupling product. The present invention further relates to a product supplemented with said coupling product. The present invention further relates to the use of said coupling product as an aroma chemical. BACKGROUND OF THE INVENTION Filbertone (5-methyl-2-hepten-4-one, (1)) is the principal flavour compound of hazelnut (Figure 1) [1,2],and is used principally for its nutty, warm and slightly fruity scent. It adds depth and richness to fragrances, often used in conjunction with other ingredients to create aromatic blends. The threshold for detection of 1 is at 5*10-6ppm resulting in a soft, buttery sensation [2]. Interestingly, filbertone isolated from hazelnut is not enantiomerically pure, but depending on its source has reported varying excess of the S-enantiomer [1]. The enantiomeric composition of natural filbertone varies according to the origin of the nut, the extraction conditions, the cooking state (raw or roasted), etc [3]. In order to become independent from hazelnut producers and the connected economic challenges synthetic access to filbertone is industrially relevant. The first synthesis of filbertone has been established in the 1930s [4]. Several routes have been described, which however are based on multistep total synthesis routes which do not allow for the natural label [1,2,6,7]. For example, starting from optically active (2S)-2-methylbutan-1-ol oxidation to the respective aldehyde is followed by coupling with propyllithium to yield methylheptinol. The C-C triple bond can then be reduced with LiAlH4 to give methylheptenol that is finally oxidised with MnO2 resulting in 1. DE3345784 describes the preparation of 1 by reacting 2-butylmagnesium bromide and crotonaldehyde followed by oxidation of 5-methyl-2-heptene-4-ol in a mixuture of sodium dichromate and sulfuric acid. WO2022214180 describes the synthesis of 1 in a more sustainable fashion since it is using environmentally benign methods, less toxic chemicals and claims to produce less waste [5]. Even though 1 from this novel route does not yet fulfil all requirements for a European natural claim [8], these recent activities underline the demand for natural filbertone in the aroma industry. Therefore, a problem to be solved by the invention relates to the provision of novel approaches for providing access to filbertone, and, in particular, filbertone precursors in an industrially sustainable fashion. Further problems to be solved by the present invention will become apparent from a closer consideration of the following sections. SUMMARY OF THE INVENTION The above-mentioned problem could be solved by the provision of a synthetic route allowing access to filbertone precursor, 3-hydroxy-5-methylheptan-4-one (6), from a simple starting material i.e. methyloxopentanoic acid (5a) and α-keto butyrate (4a) (Figure 2). Enzymatic or chemical dehydration of 3-hydroxy-5-methyl-heptan-4-one to 5- methyl-hept-2-ene-4-one would then provide access to 1. Employing amino acids as starting material and the use of further enzyme catalysts might allow the production of natural filbertone in a multi-enzyme cascade. DESCRIPTION OF FIGURES Figure 1 shows the chemical structure of both enantiomers of filbertone. Figure 2 illustrates the process of the invention for the enzymatic production of 3- hydroxy-5-methylheptan-4-one (4a) (Figure 2). Figure 3 illustrates the catalytic mechanism of TPP dependent TK with 5a as donor and 4a as acceptor substrates

[0020] . Figure 4 shows an SDS-PAGE of partially purified mTKgst. Known mTKgstmigrate as 73 kDa. Lane 1: SpectraTM Multicolor Broad Range Protein Ladder (Thermo Scientific), lane 2: crude extract mTKgstexpressed in BASF (10 µg), lane 3: crude extract mTKgstexpressed in TU Darmstadt (10 µg), lane 4: crude extract mTKgstwith a STOP codon in position 435 (10 µg) should migrate as 48,6 kDa, lane 5: insoluble fraction mTKgstexpressed in BASF (10 µg), lane 6: inclusion bodies mTKgstexpressed in TU Darmstadt (10 µg), lane 7: inclusion bodies mTKgstwith a STOP codon in position 435 (10 µg). Figure 5 shows the GC-chromatogram of a reaction using 5a and 4b as catalysed by TKgst102L / L118I / H474S. Figure 6 shows a diagram summarising the results of GC analytics of TK products obtained at different concentrations of the substrates propanal and MOPA. Figure 7 shows the GC data of the conversion of a mixture of Propanal (4b) and 2- Methylbutanal (5b). Figure 8 shows the GC data of the conversion of a mixture of alpha-Ketobutyrate (4a) and MOPA (5a). ABBREVIATIONS aa: amino acid AT: branched chain acid aminotransferase AHIAR: acetohydroxy acid isomeroreductase AHAS: acetohydroxy acid synthase DAAO: D-amino acid oxidase DHAD: Dihydroxy acid dehydratase GC: gas chromatography HPLC: High-performance liquid chromatography IPTG: Isopropyl β-d-1-thiogalactopyranoside ^-KB: alpha ketobutyrate or 2-oxobutanoic acid Km: kanamycin LB: Luria-Bertani Mbutanal: methyl butanal MOPA: 3-Methyl-2-oxovaleric acid MS: mass spectrometry mTKgst: modified transketolase from Geobacillus stearothermophilus OD: Optical density ON: overnight PDC: Pyruvate decarboxylase Prop: propanal rcf: relative centrifugal force rpm: revolutions per minute TEA: triethanolamine TD: threonine dehydrogenase thrDH: threonine dehydratase TPP: thiamine diphosphate TK: transketolase TKgstor gstTK: transketolase from Geobacillus stearothermophilus TKecoor ecoTK: transketolase from Escherichia coli DETAILED DESCRIPTIN OF THE INVENTION 1. DEFINITIONS a) General Definitions For the descriptions herein and the appended claims, the use of “or” means “and / or” unless stated otherwise. Similarly, “comprise”, “comprises”, “comprising”, “include”, “includes”, and “including” are interchangeable and not intended to be limiting. It is to be further understood that where descriptions of various embodiments use the term "comprising," those skilled in the art would understand that in some specific instances, an embodiment can be alternatively described using language "consisting essentially of" or "consisting of”. The terms "purified", "substantially purified", and "isolated" as used herein refer to the state of being free of other, dissimilar compounds with which a compound of the invention is normally associated in its natural state, so that the "purified", "substantially purified", and "isolated" subject comprises at least 0.1%, 0.5%, 1%, 5%, 10%, or 20%, or at least 50% or 75% of the mass, by weight, of a given sample. In one embodiment, these terms refer to the compound of the invention comprising at least 95, 96, 97, 98, 99 or 100%, of the mass, by weight, of a given sample. As used herein, the terms "purified," "substantially purified," and "isolated" when referring to a nucleic acid or protein, or nucleic acids or proteins, also refers to a state of purification or concentration different than that which occurs naturally, for example in an prokaryotic or eukaryotic environment, like, for example in a bacterial or fungal cell, or in the mammalian organism, especially human body. Any degree of purification or concentration greater than that which occurs naturally, including (1) the purification from other associated structures or compounds or (2) the association with structures or compounds to which it is not normally associated in said prokaryotic or eukaryotic environment, are within the meaning of "isolated”. The nucleic acid or protein or classes of nucleic acids or proteins, described herein, may be isolated, or otherwise associated with structures or compounds to which they are not normally associated in nature, according to a variety of methods and processes known to those of skill in the art. The term “about” indicates a potential variation of ± 25% of the stated value, in particular ± 15%, ± 10 %, more particularly ± 5%, ± 2% or ± 1%. The term "substantially" describes a range of values of from about 80 to 100%, such as, for example, 85-99.9%, in particular 90 to 99.9%, more particularly 95 to 99.9%, or 98 to 99.9% and especially 99 to 99.9%. A “main product” in the context of the present invention designates a single com pound or a group of at least 2 compounds, like 2, 3, 4, 5 or more, particularly 2 or 3 com pounds, which single compound or group of compounds is “predominantly” prepared by a reaction as described herein, and is contained in said reaction in a predominant proportion based on the total amount of the constituents of the product formed by said reaction. Said proportion may be a molar proportion, a weight proportion or, particularly based on chromatographic analytics, an area proportion calculated from the corresponding chromatogram of the reaction products. A “side product” in the context of the present invention designates a single compound or a group of at least 2 compounds, like 2, 3, 4, 5 or more, particularly 2 or 3 compounds, which single compound or group of compounds is not “predominantly” prepared by a reaction as described herein. Because of the reversibility of enzymatic reactions, the present invention relates, unless otherwise stated, to the enzymatic or biocatalytic reactions described herein in both directions of reaction. “Yield" and / or the "conversion rate" of a reaction according to the invention is determined over a defined period of, for example, 4, 6, 8, 10, 12, 16, 20, 24, 36 or 48 hours, in which the reaction takes place. In particular, the reaction is carried out under precisely defined conditions, for example at “standard conditions” as herein defined. The different yield parameters ("Yield" or YP / S; "Specific Productivity Yield"; or Space-Time-Yield (STY)) are well known in the art and are determined as described in the literature. "Yield" and "YP / S" (each expressed in mass of product produced / mass of material consumed) are herein used as synonyms. The term “aroma chemical” denotes a substance which is used to obtain a sensory or organoleptic impression. The term "olfactory impression" or “note” denotes an odor impression without any positive or negative judgement. The term “aroma composition”, as used herein, refers to a composition which induces an aroma. The term aroma composition comprises at least the aroma chemical as defined herein, possibly together with other substances which overall define an “odor composition” and / or “flavor composition”. An odor composition being a composition, which predominately induces an odor impression, a flavor composition being a composition, which predominantly induces a taste impression. If the present disclosure refers to features, parameters and ranges thereof of different degree of preference (including general, not explicitly preferred features, parameters and ranges thereof) then, unless otherwise stated, any combination of two or more of such features, parameters and ranges thereof, irrespective of their respective degree of preference, is encompassed by the disclosure of the present description. b) (Bio)chemical definitions The term "biocatalytic process” within the meaning of the present disclosure refers to any process carried out in the presence of catalytic activity of at least one enzyme according to the invention, i.e. processes in the presence of raw, or purified, dissolved, dispersed or immobilized enzyme, or in the presence of whole microbial living, or resting or inactivated, disrupted cells, which have or express such enzyme activity. Biocatalytic processes therefore include both enzymatic and microbial processes. An “enzyme” as described herein can be a native or recombinantly produced enzyme, it may be the wild type enzyme or genetically modified by suitable mutations or by C- and / or N-terminal amino acid sequence extensions, like His-tag containing sequences. The enzyme can basically be mixed with cellular, for example protein impurities, but particularly is in pure form. Suitable methods of detection are described for example in the experimental section given below or are known from the literature. "Immobilization" means, according to the invention, the covalent or noncovalent binding of a biocatalyst used according to the invention on a solid, i.e. essentially insoluble in the surrounding liquid medium, carrier material. According to the invention, whole cells, such as the recombinant microorganisms used according to the invention, can correspondingly also be immobilized by means of such carriers. As used herein, the term “acceptor molecule” refers to a chemical entity capable of accepting lone electron pairs from a donor as defined herein during the course of an enzymatically catalyzed reaction, particularly a transaldolase or transketolase catalyzed reaction. Typical acceptor molecules according to the present invention are propanal and 2-methylbutanal. As used herein, the term “donor molecule” refers to a chemical entity capable of donating lone electron pairs to an acceptor molecule as defined herein during the course of an enzymatically catalyzed reaction, particularly a transaldolase or transketolase catalyzed reaction. Typical donor molecules according to the present invention are α-KB and MOPA. As used herein, the term “carboligation reaction “ refers to the transaldolase or transketolase catalyzed coupling reaction between a donor and an acceptor molecule as defined herein above to afford the corresponding coupling products. As used herein, the term “carboligation product” and “coupling product” are to be understood as synonyms and refer to the reaction product of the carboligation reaction as defined herein above. In the following Table 1, structures and designations of donors, acceptors and coupling products are summarized: Table 1: structures and designations of donors, acceptors and products Donor (designation) (5a) (4a) (5a) (4a) Acceptor (designation) (4b) (5b) (5b) (4b) Product (designation) (6) (7) (10) (8) IUPAC name 3-Hydroxy-5- 4-Hydroxy-5- 5-Hydroxy-3,6- methyl-heptan-4- methyl-3- dimeth 4-Hydroxy-3- of product yl-4- one heptanone octanone hexanone As used herein, the term “transaldolase” generally refers to those enzymes capable of catalyzing the reversible interconversion between the pair sedoheptulose-7- phosphate and glyceraldehyde-3-phosphate and the pair erythrose-4-phosphate and fructose-6-phosphate. More particularly said transaldolase refers to enzymes belonging to EC 2.2.1.2. Suitable enzymes are obtainable for example from Thermoplasma acidophilum. As used herein, the term “transketolase” generally refers to those enzymes capable of catalyzing the reversible conversion between sedoheptulose-7-phosphate and D-glyceraldehyde-3-phosphate to D-ribose-5-phosphate and D-xylulose-5- phosphate and / or those enzymes capable of reversibly converting D-fructose-6- phosphate and D-glyceraldehyde-3-phosphate to D-xylulose-5-phosphate and erythrose-4-phosphate. More particularly said transketolase refers to enzymes belonging to EC 2.2.1.1. Suitable enzymes are obtainable for example from Geobacillus in particular Geobacillus stearothermophilus and present an amino acid sequence corresponding to SEQ ID NO: 2 or mutants thereof presenting the following amino acid substitutions: H68G, H102M, H28T, D470S, D470T, H102L / H474N, L118F / H474N, H102Y / H474N, H102L / L118I, L382N / D470S, L382D / D470S, L382N / D470T, L382E / D470T, H102L / L118I / H474S or H102V / L118F / H474D. Further examples are enzymes obtainable from or Escherichia, in particular Escherichia coli and present an amino acid sequence corresponding to SEQ ID NO: 34 or mutants thereof presenting the following mutations: H26T, H66A, H66G, H100L, H100L / L116I or H100L / L116I / H473S. As used herein, the term “Threonine dehydratase” generally refers to those enzymes capable of catalyzing the reversible interconversion between threonine and α- KB. More particularly said threonine dehydratase refers to enzymes belonging to EC 4.3.1.19. Suitable enzymes are obtainable for example from Escherichia coli str. K-12 and present an amino acid sequence corresponding to SEQ ID NO: 48. As used herein, the term “D-amino acid oxidase “generally refers to those enzymes capable of catalyzing the reversible interconversion between D-isoleucine and MOPA. More particularly said D-amino acid oxidase refers to enzymes belonging to EC 1.4.3.3. Suitable enzymes are obtainable for example from Rhodotorula gracilis and present an amino acid sequence corresponding to SEQ ID NO: 50. As used herein, the term “racemase” refers to an enzyme which catalyzes the stereochemical inversion around the asymmetric carbon atom in a substrate having one center of asymmetry. Particularly, within the context of the present disclosure the term racemase is to be interpreted as to “amino acid racemase”, namely as an enzyme which catalyzes the reversible of an L-amino acid to a D- amino acid, more particularly of L- threonine to D-threonine and belong to EC 5.1.1.10 or 5.1.1.21. Suitable enzymes are obtainable for example from Lentilactobacillus buchneri. The term "domain" refers to a set of amino acids or a partial sequence of amino acids residues conserved at specific positions along an alignment of sequences of evolutionarily related proteins. While amino acids at other positions can vary between protein homologues, amino acids that are highly conserved at specific positions of such domain indicate amino acids that are likely essential in the structure, stability or function of a protein. Identified by their high degree of conservation in aligned sequences of a family of protein homologues, they can be used as identifiers to determine if any polypeptide in question belongs to a previously identified polypeptide family. The term "motif" or “consensus sequence" or "signature" refers to a short conserved region in the sequence of evolutionarily related proteins. Motifs are frequently highly conserved parts of domains, but may also include only part of the domain. A “protein family” is defined as a group of proteins that share a common evolutionary origin reflected by their related functions, similarities in sequence, or similar primary, secondary or tertiary structure. Proteins within protein families are usually homologous and have similar structure of conserved functional domains and motifs. Specialist databases exist for the identification of domains, for example, SMART (Schultz et al. (1998) Proc. Natl. Acad. Sci. USA 95, 5857-5864; Letunic et al. (2002) Nucleic Acids Res 30, 242-244), InterPro (Mulder et al., (2003) Nucl. Acids. Res. 31, 315-318), Prosite (Bucher and Bairoch (1994), A generalized profile syntax for biomolecular sequences motifs and its function in automatic sequence interpretation. (In) ISMB-94; Proceedings 2nd International Conference on Intelligent Systems for Molecular Biology. Altman R., Brutlag D., Karp P., Lathrop R., Searls D., Eds., pp 53-61, AAAI Press, Menlo Park; Hulo et al., Nucl. Acids. Res.32:D134-D137, (2004)), or Pfam (Bateman et al., Nucleic Acids Research 30(1): 276-280 (2002)). Domains or motifs may also be identified using routine techniques, such as by sequence alignment. 2. PARTICULAR EMBODIMENTS The present invention relates to the following particular embodiments: 1. A biocatalytic process the production of aroma chemicals, which process comprises an enzyme catalyzed conversion, i.p. carboligation, of a) a donor molecule (D) selected from 2-oxobutanoic acid (α-KB) and 3- methyl-2-oxopentanoic acid (MOPA) and an acceptor molecule (A) selected from propanal and 2-methylbutanal, optionally in the presence of catalytic amounts of the coenzyme TPP; or b) two identical or different donor molecules (D) selected from α-KB and MOPA; or c) two identical or different acceptor molecules (A) selected from propanal and 2-methylbutanal; and the subsequent isolation of the obtained conversion, i.p. carboligation product. 2. The biocatalytic process of embodiment 1, wherein said carboligation reaction is catalyzed by a transaldolase (TA) (EC 2.2.1.2) or transketolase (TK) (EC 2.2.1.1) 3. The biocatalytic process of embodiment 1 or 2, wherein coupling product is selected from 3-hydroxy-5-methyl-heptan-4-one, 4-hydroxy-5-methyl-heptan-3- one, 5-hydroxy-3,6-dimethyl-octan-4-one, and 4-hydroxy-hexan-3-one or a combination of at least two thereof, each either in stereoisomerically pure form or as a mixture of stereoisomers. 4. The biocatalytic process of anyone of the preceding embodiments, which further comprises the enzymatic or chemical dehydration of 3-hydroxy-5-methyl-heptan- 4-one to 5-methyl-hept-2-ene-4-one, either in stereoisomerically pure form or as a mixture of stereoisomers. In particular, the dehydration step could be performed in the presence of catalytic amounts of an acid, in particular with sulfuric acid, in an acid-catalysed dehydratation reaction. 5. The biocatalytic process of embodiment 4, wherein the obtained product is filbertone (5-methyl-(E)-2-heptene-4-one) either in stereoisomerically pure form or as a mixture of stereoisomers. 6. The biocatalytic process of anyone of the preceding embodiments, wherein a TK isolated from microorganisms of the genus Geobacillus or Escherichia, in particular Geobacillus stearothermophilus or Escherichia coli. or an enzyme mutant, derived therefrom, is applied. 7. The biocatalytic process of embodiment 6, wherein said enzyme mutant is selected from single, double or triple mutants of the G. stearothermophilus TK wild-type sequence according to SEQ ID NO:51; or of the E. coli. TK wild-type sequence according to SEQ ID NO: 56. 8. The biocatalytic process of embodiment 6 or 7, wherein the G. stearothermophilus TK mutant is selected from single mutants H68G, H102M, H28T, D470S and D470T double mutants H102L / H474N, L118F / H474N; H102Y / H474N, H102L / L118I, L382N / D470S; L382D / D470S; L382N / D470T and L382E / D470T; and triple mutants H102L / L118I / H474S and H102V / L118F / H474D each derived from a TK sequence of SEQ ID NO:51, either with or without an N- terminal or C-terminal His tag motif, or a sequence having a degree of sequence identity of at least 70% while retaining TK activity. 9. The biocatalytic process of embodiment 6 to 7, wherein said TK mutant is selected from a) proteins comprising a polypeptide with an amino acid sequence as per SEQ ID NO: 51; b) proteins obtained by single or multiple deletion, insertion, substitution, addition, inversion or a combination thereof, comprising a polypeptide with a sequence identity of at least 45%, 50%, 55%, 60%, 65%, 70%, in particular at least 75% or 80%, preferably at least 85%, such as, for example, at least 90, 91, 92, 93, 94, 95, 96, 97, 98 or 99%, to the amino acid sequence as per SEQ ID NO: 51; and c) proteins which are functionally equivalent to a) or b) and which are able to catalyze an enzyme catalyzed reaction of an acceptor and donor molecule as defined herein above. 10. The biocatalytic process of embodiment 6 or 7, wherein the E.coli TK mutant is selected from single mutants H26T, H66A, H66G and H100L double mutant H100L / L116I; and triple mutant H100L / L116I / H473S each derived from a TK sequence of SEQ ID NO:56, either with or without an N- terminal or C-terminal His tag motif, or a sequence having a degree of sequence identity of at least 70% while retaining TK activity. Any mutation position as referred to hereinabove relates to the sequence position of the respective wild-type enzyme without His-Tag 11. The biocatalytic process of embodiment 6 or 7, wherein said TK mutant is selected from a) proteins comprising a polypeptide with an amino acid sequence as per SEQ ID NO: 51 or 56; b) proteins obtained by single or multiple deletion, insertion, substitution, addition, inversion or a combination thereof, comprising a polypeptide with a sequence identity of at least 45%, 50%, 55%, 60%, 65%, 70%, in particular at least 75% or 80%, preferably at least 85%, such as, for example, at least 90, 91, 92, 93, 94, 95, 96, 97, 98 or 99%, to the amino acid sequence as per SEQ ID NO: 51 or 56; and c) proteins which are functionally equivalent to a) or b) and which are able to catalyze an enzyme catalyzed reaction of an acceptor and donor molecule as defined herein above. The biocatalytic process of anyone of the embodiments 6 to 11, wherein a TK mutant is applied , which is selected from mutants having an amino acid sequence according to SEQ ID Nos: 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 36, 38, 40, 42, 44, or 46, each either with or without an N-terminal or C-terminal His tag motif, and amino acid sequences having a degree of sequence identity of at least 70% thereto, while retaining the respective mutation position or mutation positions and retaining the ability to catalyze anyone of the above identifies TK-catalyzed carboligation reactions. The biocatalytic process of embodiments 6 to 12, wherein said TK mutant is selected from among a) proteins comprising a polypeptide with an amino acid sequence as per any of SEQ ID Nos: 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 36, 38, 40, 42, 44, or 46; b) proteins obtained by single or multiple deletion, insertion, substitution, addition, inversion or a combination thereof, comprising a polypeptide with a sequence identity of at least 45%, 50%, 55%, 60%, 65%, 70%, in particular at least 75% or 80%, preferably at least 85%, such as, for example, at least 90, 91, 92, 93, 94, 95, 96, 97, 98 or 99%, to the amino acid sequence as per any of SEQ ID Nos: 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 36, 38, 40, 42, 44, or 46; and c) proteins which are functionally equivalent to a) or b) and which are able to catalyze an enzyme catalyzed reaction of an acceptor and donor molecule as defined herein above. The biocatalytic process of anyone of the preceding embodiments, further comprising the step of simultaneous or non-simultaneous enzyme catalyzed formation of anyone of the donor molecules (D). The biocatalytic process of anyone of the preceding embodiments, wherein 2- oxobutanoic acid (α-KB) is formed from (D / L)-threonine by the enzymatic action of a Threonine Dehydratase (ThrDH) (EC 4.3.1.19), in particular, having an amino acid sequence according to SEQ ID NO: 48, or a sequence having a degree of sequence identity of at least 70% thereto; and 3-methyl-2- oxopentanoic acid (MOPA) is formed from D-isoleucine by the enzymatic action of a D-Amino Acid Oxidase (DAAO) (EC 1.4.3.3), in particular, having an amino acid sequence according to SEQ ID NO: 50, or a sequence having a degree of sequence identity of at least 70% thereto. The biocatalytic process of embodiment 15, wherein said D-isoleucine is formed from L-isoleucine via enzymes catalyzed racemization through the action of an amino acid racemase (EC 5.1.1.10 or 5.1.1.21) The biocatalytic process of embodiment 16, wherein said L-isoleucine is enzymatically formed from L-threonine in the presence of (stoichiometric amounts of) pyruvate in an enzyme-catalyzed multistep reaction sequence (such as) as described in the scheme Below (Yin et al, Metabolic engineering, 14 (2012) 542– 550): Scheme 1: enzyme-catalyzed multistep reaction sequence for the synthesis of L-isoleucine from L-threonine. L Threonine is converted to 2-KB under catalysis of a threonine dehydrogenase (TD).2-KB is then reacted with pyruvate under catalysis of a converted to 2-Aceto- 2-hydroxybutyrrate under catalysis of an acetohydroxy acid synthase (AHAS).2- Aceto-2-hydroxybutyrrate can be reacted under catalysis of an acetohydroxy acid isomeroreductase (AHIAR), thereby affording to 2,3-dihydroxy-3-methylvalereate. The latter can then be converted to 2-keto-3-methylvalerate by reaction with a Dihydroxy acid dehydratase (DHAD). Finally, L-isoleucine can be generated by reacting 2-keto-3-methylvalerate in presence of a branched chain acid aminotransferase (AT). 18. The biocatalytic process as per any of the preceding embodiments, wherein the conversion is carried out in one-phase aqueous systems or in two-phase aqueous-organic or solid-liquid systems, in particular in one-phase aqueous systems. 19. The biocatalytic process as per any of the preceding embodiments, wherein the conversion is carried out at a temperature in the range from 0 to 60°C, in particular from 10 to 55°C, more particularly from 45 to 55°C and / or a pH value in the range of from 4 to 8, in particular from 6 to 7.5. 20. A nucleic acid molecule encoding at least one TK mutant as defined in embodiment 7, 8, 9 or 10. 21. The nucleic acid molecule of embodiment 20 comprising a nucleotide sequence selected from SEQ ID NOs: 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 35, 37, 39, 41, 43 or 45 and nucleotide sequences having a degree of sequence identity of at least 70% thereto, while retaining the respective mutation position or mutation positions of the encoded TK mutant and retaining the ability of said mutant to catalyze anyone of the above identifies TK-catalyzed carboligation reactions. 22. An expression construct comprising under the control of at least one regulatory element the coding sequence for at least one TK mutant as defined in anyone of the embodiments 20 and 21. A recombinant vector comprising at least one nucleic acid or expression construct of anyone of the embodiments 20 to 22. The expression construct of embodiment 22 or the recombinant vector of embodiment 23 further comprising under the control of at least one regulatory element the coding sequence for a ThrDH and / or a DAAO as defined in embodiment 15 and optionally a racemase as defined in embodiment 16. A recombinant non-human host carrying at least one recombinant vector of embodiment 23 or at least one nucleic acid or expression construct of anyone of the embodiments 20 to 22. A biocatalytic process of anyone of embodiments 1 to 19, which comprises the cultivation of at least one recombinant host of embodiment 25 under conditions allowing the TK catalyzed production of at least one carboligation product of embodiment 2 and isolating the same from the production medium. A combination of compounds comprising more than one compound as defined in anyone of the embodiments 3 to 5. A composition supplemented with at least one compound of anyone of the embodiments 3 to 5 or a combination of compounds of embodiment 27. Use of a compound as defined in embodiments 3 to 5 as an aroma chemical, in particular, to impart an aroma impression to a composition. A method of imparting an aroma impression to a composition comprising at least the step of adding at least one compound of anyone of the embodiments 3 to 5 or the combination of embodiment 27 to a composition. The use or method according to any of the embodiments 29 or 30, wherein the aroma impression is selected from the group consisting of a hazelnut note, sweet note, chocolatey note, nutty note, roasted note, gourmand note, forest tree note and natural note. The use or method according to any of the embodiments 29 to 31, wherein the at least one compound of anyone of the embodiments 3 to 5 or the combination of compounds of embodiment 22 is present in the range of ≥ 0.01 wt.% to ≤ 70.0 wt.%, based on the total weight of the composition. The use or method according to embodiment 29 to 32, wherein the composition is selected from perfume compositions, body care compositions, hygiene articles, cleaning compositions, textile detergent compositions, compositions for scent dispensers, foods, food supplements, pharmaceutical compositions and crop protection compositions. A composition comprising at least one compound of anyone of the embodiments 3 to 5 or a combination of compounds of embodiment 27 and (i) at least one aroma chemical (X) other than the compound of the embodiments 3 to 5 or the combination of compounds of embodiment 27 or (ii) at least one non-aroma chemical carrier, or (iii) both of (i) and (ii). The composition according to embodiment 34, wherein the compound of anyone of the embodiments 3 to 5 or a combination of compounds of embodiment 27 are present in a total amount in the range of ≥ 0.01 wt.% to ≤ 70.0 wt.%, based on the total weight of the composition. The composition according to embodiment 34, wherein the at least one non-aroma chemical carrier (ii) is selected from the group consisting of surfactants, oil components, antioxidants, deodorant-active agents and solvents. The composition according to any of the embodiments 34 to 36, wherein the composition is selected from the group consisting of perfume compositions, body care compositions, hygiene articles, cleaning compositions, textile detergent compositions, compositions for scent dispensers, foods, food supplements, pharmaceutical compositions and crop protection compositions. FURTHER ASPECTS AND EMBODIMENTS OF THE INVENTION 1. Proteins or Enzymes The present invention is not limited to the concretely disclosed proteins or enzymes with or mutants thereof, but rather also extends to functional equivalents thereof. The present invention also relates to "functional equivalents" (also designated as “analogs” or “functional mutations”) of the polypeptides specifically described herein. For example, "functional equivalents" refer to polypeptides which, in a test used for determining enzymatic activity display at least a 1 to 10 %, or at least 20 %, or at least 50 %, or at least 75 %, or at least 90 % higher or lower activity, as that of the polypeptides specifically described herein. "Functional equivalents”, according to the invention, also cover particular mutants, which, in at least one sequence position of an amino acid sequences stated herein, have an amino acid that is different from that concretely stated one, but nevertheless possess one of the aforementioned biological activities, as for example enzyme activity. "Functional equivalents" thus comprise mutants obtainable by one or more, like 1 to 20, in particular 1 to 15 or 5 to 10 amino acid additions, substitutions, in particular conservative substitutions, deletions and / or inversions, where the stated changes can occur in any sequence position, provided they lead to a mutant with the profile of properties according to the invention. Functional equivalence is in particular also provided if the activity patterns coincide qualitatively between the mutant and the unchanged polypeptide, i.e. if, for example, interaction with the same agonist or antagonist or substrate, however at a different rate, (i.e. expressed by a EC50 or IC50 value or any other parameter suitable in the present technical field) is observed. Examples of suitable (conservative) amino acid substitutions are shown in the following table: Original residue Examples of substitution Ala Ser Arg Lys Asn Gln; His Asp Glu Cys Ser Gln Asn Glu Asp Gly Pro His Asn ; Gln Ile Leu; Val Leu Ile; Val Lys Arg ; Gln ; Glu Met Leu ; Ile Phe Met ; Leu ; Tyr Ser Thr Thr Ser Trp Tyr Tyr Trp ; Phe Val Ile; Leu "Functional equivalents" in the above sense are also "precursors" of the polypeptides described herein, as well as "functional derivatives" and "salts" of the polypeptides. "Precursors" are in that case natural or synthetic precursors of the polypeptides with or without the desired biological activity. The expression "salts" means salts of carboxyl groups as well as salts of acid addition of amino groups of the protein molecules according to the invention. Salts of carboxyl groups can be produced in a known way and comprise inorganic salts, for example sodium, calcium, ammonium, iron and zinc salts, and salts with organic bases, for example amines, such as triethanolamine, arginine, lysine, piperidine and the like. Salts of acid addition, for example salts with inorganic acids, such as hydrochloric acid or sulfuric acid and salts with organic acids, such as acetic acid and oxalic acid, are also covered by the invention. "Functional derivatives" of polypeptides according to the invention can also be produced on functional amino acid side groups or at their N-terminal or C-terminal end using known techniques. Such derivatives comprise for example aliphatic esters of carboxylic acid groups, amides of carboxylic acid groups, obtainable by reaction with ammonia or with a primary or secondary amine; N-acyl derivatives of free amino groups, produced by reaction with acyl groups; or O-acyl derivatives of free hydroxyl groups, produced by reaction with acyl groups. ”Functional equivalents” naturally also comprise polypeptides that can be obtained from other organisms, as well as naturally occurring variants. For example, areas of homologous sequence regions can be established by sequence comparison, and equivalent polypeptides can be determined on the basis of the concrete parameters of the invention. "Functional equivalents" also comprise “fragments”, like individual domains or sequence motifs, of the polypeptides according to the invention, or N- and or C-terminally truncated forms, which may or may not display the desired biological function. Particularly such “fragments” retain the desired biological function at least qualitatively. "Functional equivalents" are, moreover, fusion proteins, which have one of the polypeptide sequences stated herein or functional equivalents derived there from and at least one further, functionally different, heterologous sequence in functional N-terminal or C-terminal association (i.e. without substantial mutual functional impairment of the fusion protein parts). Non-limiting examples of these heterologous sequences are e.g. signal peptides, histidine anchors or enzymes. “Functional equivalents” which are also comprised in accordance with the invention are homologs to the specifically disclosed polypeptides. These have at least 60%, particularly at least 75%, in particular at least 80 or 85%, such as, for example, 90, 91, 92, 93, 94, 95, 96, 97, 98 or 99%, homology (or identity) to one of the specifically disclosed amino acid sequences, calculated by the algorithm of Pearson and Lipman, Proc. Natl. Acad, Sci. (USA) 85(8), 1988, 2444-2448. A homology or identity, expressed as a percentage, of a homologous polypeptide according to the invention means in particular an identity, expressed as a percentage, of the amino acid residues based on the total length of one of the amino acid sequences described specifically herein. The identity data, expressed as a percentage, may also be determined with the aid of BLAST alignments, algorithm blastp (protein-protein BLAST), or by applying the Clustal settings specified herein below. In the case of a possible protein glycosylation, "functional equivalents" according to the invention comprise polypeptides as described herein in deglycosylated or glycosylated form as well as modified forms that can be obtained by altering the glycosylation pattern. Functional equivalents or homologues of the polypeptides according to the invention can be produced by mutagenesis, e.g. by point mutation, lengthening or shortening of the protein or as described in more detail below. Functional equivalents or homologs of the polypeptides according to the invention can be identified by screening combinatorial databases of mutants, for example shortening mutants. For example, a variegated database of protein variants can be produced by combinatorial mutagenesis at the nucleic acid level, e.g. by enzymatic ligation of a mixture of synthetic oligonucleotides. There are a great many methods that can be used for the production of databases of potential homologues from a degenerated oligonucleotide sequence. Chemical synthesis of a degenerated gene sequence can be carried out in an automatic DNA synthesizer, and the synthetic gene can then be ligated in a suitable expression vector. The use of a degenerated genome makes it possible to supply all sequences in a mixture, which code for the desired set of potential protein sequences. Methods of synthesis of degenerated oligonucleotides are known to a person skilled in the art. In the prior art, several techniques are known for the screening of gene products of combinatorial databases, which were produced by point mutations or shortening, and for the screening of cDNA libraries for gene products with a selected property. These techniques can be adapted for the rapid screening of the gene banks that were produced by combinatorial mutagenesis of homologues according to the invention. The techniques most frequently used for the screening of large gene banks, which are based on a high- throughput analysis, comprise cloning of the gene bank in expression vectors that can be replicated, transformation of the suitable cells with the resultant vector database and expression of the combinatorial genes in conditions in which detection of the desired activity facilitates isolation of the vector that codes for the gene whose product was detected. Recursive Ensemble Mutagenesis (REM), a technique that increases the frequency of functional mutants in the databases, can be used in combination with the screening tests, in order to identify homologues. An embodiment provided herein provides orthologs and paralogs of polypeptides disclosed herein as well as methods for identifying and isolating such orthologs and paralogs. A definition of the terms “ortholog” and “paralog” is given below and applies to amino acid and nucleic acid sequences. The polypeptides of the invention include all active forms, including active subsequences, e.g., catalytic domains or active sites, of an enzyme of the invention. In one aspect, the invention provides catalytic domains or active sites as set forth below. In one aspect, the invention provides a peptide or polypeptide comprising or consisting of an active site domain as predicted through use of a database such as Pfam (http: / / pfam.wustl.edu / hmmsearch.shtml) (which is a large collection of multiple sequence alignments and hidden Markov models covering many common protein families, The Pfam protein families database, A. Bateman, E. Birney, L. Cerruti, R. Durbin, L. Etwiller, S. R. Eddy, S. Griffiths-Jones, K. L. Howe, M. Marshall, and E. L. L. Sonnhammer, Nucleic Acids Research, 30(1):276-280, 2002) or equivalent, as for example InterPro and SMART databases (http: / / www.ebi.ac.uk / interpro / scan.html, http: / / smart.embl-heidelberg.de / ). The invention also encompasses “polypeptide variant” having the desired activity, wherein the variant polypeptide is selected from an amino acid sequence having at least 50%.55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99%, sequence identity to a specific, in particular natural, amino acid sequence as referred to by a specific SEQ ID NO and contains at least one substitution modification relative said SEQ ID NO ,and in particular also retains the respective activity of the related wild-type polypeptide . 2. Nucleic acids The invention also relates to nucleic acid sequences that code for polypeptides as disclosed herein. In particular, the invention also relates to nucleic acid sequences (single-stranded and double-stranded DNA and RNA sequences, e.g. cDNA, genomic DNA and mRNA), coding for one of the above polypeptides and their functional equivalents, which can be obtained for example using artificial nucleotide analogs. The invention relates both to isolated nucleic acid molecules, which code for polypeptides according to the invention or biologically active segments thereof, and to nucleic acid fragments, which can be used for example as hybridization probes or primers for identifying or amplifying coding nucleic acids according to the invention. The present invention also relates to nucleic acids with a certain degree of “identity” to the sequences specifically disclosed herein. "Identity" between two nucleic acids means identity of the nucleotides, in each case over the entire length of the nucleic acid. The “identity” between two nucleotide sequences (the same applies to peptide or amino acid sequences) is a function of the number of nucleotide residues (or amino acid residues) or that are identical in the two sequences when an alignment of these two sequences has been generated. Identical residues are defined as residues that are the same in the two sequences in a given position of the alignment. The percentage of sequence identity, as used herein, is calculated from the optimal alignment by taking the number of residues identical between two sequences dividing it by the total number of residues in the shortest sequence and multiplying by 100. The optimal alignment is the alignment in which the percentage of identity is the highest possible. Gaps may be introduced into one or both sequences in one or more positions of the alignment to obtain the optimal alignment. These gaps are then taken into account as non-identical residues for the calculation of the percentage of sequence identity. Alignment for the purpose of determining the percentage of amino acid or nucleic acid sequence identity can be achieved in various ways using computer programs and for instance publicly available computer programs available on the world wide web. Particularly, the BLAST program (Tatiana et al, FEMS Microbiol Lett., 1999, 174:247-250, 1999) set to the default parameters, available from the National Center for Biotechnology Information (NCBI) website at ncbi.nlm.nih.gov / BLAST / bl2seq / wblast2.cgi, can be used to obtain an optimal alignment of protein or nucleic acid sequences and to calculate the percentage of sequence identity. In another example the identity may be calculated by means of the Vector NTI Suite 7.1 program of the company Informax (USA) employing the Clustal Method (Higgins DG, Sharp PM. ((1989))) with the following settings: Multiple alignment parameters: Gap opening penalty 10 Gap extension penalty 10 Gap separation penalty range 8 Gap separation penalty off % identity for alignment delay 40 Residue specific gaps off Hydrophilic residue gap off Transition weighing 0 Pairwise alignment parameter: FAST algorithm on K-tuple size 1 Gap penalty 3 Window size 5 Number of best diagonals 5 Alternatively the identity may be determined according to Chenna, et al. (2003), the web page: http: / / www.ebi.ac.uk / Tools / clustalw / index.html# and the following settings DNA Gap Open Penalty 15.0 DNA Gap Extension Penalty 6.66 DNA Matrix Identity Protein Gap Open Penalty 10.0 Protein Gap Extension Penalty 0.2 Protein matrix Gonnet Protein / DNA ENDGAP -1 Protein / DNA GAPDIST 4 All the nucleic acid sequences mentioned herein (single-stranded and double- stranded DNA and RNA sequences, for example cDNA and mRNA) can be produced in a known way by chemical synthesis from the nucleotide building blocks, e.g. by fragment condensation of individual overlapping, complementary nucleic acid building blocks of the double helix. Chemical synthesis of oligonucleotides can, for example, be performed in a known way, by the phosphoamidite method (Voet, Voet, 2nd edition, Wiley Press, New York, pages 896-897). The accumulation of synthetic oligonucleotides and filling of gaps by means of the Klenow fragment of DNA polymerase and ligation reactions as well as general cloning techniques are described in Sambrook et al. (1989), see below. The nucleic acid molecules according to the invention can in addition contain non-translated sequences from the 3' and / or 5' end of the coding genetic region. The invention further relates to the nucleic acid molecules that are complementary to the concretely described nucleotide sequences or a segment thereof. The nucleotide sequences according to the invention make possible the production of probes and primers that can be used for the identification and / or cloning of homologous sequences in other cellular types and organisms. Such probes or primers generally comprise a nucleotide sequence region which hybridizes under "stringent" conditions (as defined herein elsewhere) on at least about 12, particularly at least about 25, for example about 40, 50 or 75 successive nucleotides of a sense strand of a nucleic acid sequence according to the invention or of a corresponding antisense strand. “Homologous” sequences include orthologous or paralogous sequences. Methods of identifying orthologs or paralogs including phylogenetic methods, sequence similarity and hybridization methods are known in the art and are described herein. “Paralogs” result from gene duplication that gives rise to two or more genes with similar sequences and similar functions. Paralogs typically cluster together and are formed by duplications of genes within related plant species. Paralogs are found in groups of similar genes using pair-wise Blast analysis or during phylogenetic analysis of gene families using programs such as CLUSTAL. In paralogs, consensus sequences can be identified characteristic to sequences within related genes and having similar functions of the genes. “Orthologs”, or orthologous sequences, are sequences similar to each other because they are found in species that descended from a common ancestor. For instance, plant species that have common ancestors are known to contain many enzymes that have similar sequences and functions. The skilled artisan can identify orthologous sequences and predict the functions of the orthologs, for example, by constructing a polygenic tree for a gene family of one species using CLUSTAL or BLAST programs. A method for identifying or confirming similar functions among homologous sequences is by comparing of the transcript profiles in host cells or organisms, such as plants or microorganisms, overexpressing or lacking (in knockouts / knockdowns) related polypeptides. The skilled person will understand that genes having similar transcript profiles, with greater than 50% regulated transcripts in common, or with greater than 70% regulated transcripts in common, or greater than 90% regulated transcripts in common will have similar functions. Homologs, paralogs, orthologs and any other variants of the sequences herein are expected to function in a similar manner by making the host cells, organism such as plants or microorganisms producing enzymes of the invention. The term “selectable marker” refers to any gene which upon expression may be used to select a cell or cells that include the selectable marker. Examples of selectable markers are described below. The skilled artisan will know that different antibiotic, fungicide, auxotrophic or herbicide selectable markers are applicable to different target species. A nucleic acid molecule according to the invention can be recovered by means of standard techniques of molecular biology and the sequence information supplied according to the invention. For example, cDNA can be isolated from a suitable cDNA library, using one of the concretely disclosed complete sequences or a segment thereof as hybridization probe and standard hybridization techniques (as described for example in Sambrook, (1989)). In addition, a nucleic acid molecule comprising one of the disclosed sequences or a segment thereof, can be isolated by the polymerase chain reaction, using the oligonucleotide primers that were constructed on the basis of this sequence. The nucleic acid amplified in this way can be cloned in a suitable vector and can be characterized by DNA sequencing. The oligonucleotides according to the invention can also be produced by standard methods of synthesis, e.g. using an automatic DNA synthesizer. Nucleic acid sequences according to the invention or derivatives thereof, homologues or parts of these sequences, can for example be isolated by usual hybridization techniques or the PCR technique from other bacteria, e.g. via genomic or cDNA libraries. These DNA sequences hybridize in standard conditions with the sequences according to the invention. "Hybridize" means the ability of a polynucleotide or oligonucleotide to bind to an almost complementary sequence in standard conditions, whereas nonspecific binding does not occur between non-complementary partners in these conditions. For this, the sequences can be 90-100 % complementary. The property of complementary sequences of being able to bind specifically to one another is utilized for example in Northern Blotting or Southern Blotting or in primer binding in PCR or RT-PCR. Short oligonucleotides of the conserved regions are used advantageously for hybridization. However, it is also possible to use longer fragments of the nucleic acids according to the invention or the complete sequences for the hybridization. These “standard conditions” vary depending on the nucleic acid used (oligonucleotide, longer fragment or complete sequence) or depending on which type of nucleic acid – DNA or RNA – is used for hybridization. For example, the melting temperatures for DNA:DNA hybrids are approx.10 ºC lower than those of DNA:RNA hybrids of the same length. For example, depending on the particular nucleic acid, standard conditions mean temperatures between 42 and 58 °C in an aqueous buffer solution with a concentration between 0.1 to 5 x SSC (1 X SSC = 0.15 M NaCl, 15 mM sodium citrate, pH 7.2) or additionally in the presence of 50 % formamide, for example 42 °C in 5 x SSC, 50 % formamide. Advantageously, the hybridization conditions for DNA:DNA hybrids are 0.1 x SSC and temperatures between about 20 °C to 45 °C, particularly between about 30 °C to 45 °C. For DNA:RNA hybrids the hybridization conditions are advantageously 0.1 x SSC and temperatures between about 30 °C to 55 °C, particularly between about 45 °C to 55 °C. These stated temperatures for hybridization are examples of calculated melting temperature values for a nucleic acid with a length of approx.100 nucleotides and a G + C content of 50 % in the absence of formamide. The experimental conditions for DNA hybridization are described in relevant genetics textbooks, for example Sambrook et al., 1989, and can be calculated using formulae that are known by a person skilled in the art, for example depending on the length of the nucleic acids, the type of hybrids or the G + C content. A person skilled in the art can obtain further information on hybridization from the following textbooks: Ausubel et al. (eds), (1985), Brown (ed) (1991). "Hybridization" can in particular be carried out under stringent conditions. Such hybridization conditions are for example described in Sambrook (1989), or in Current Protocols in Molecular Biology, John Wiley & Sons, N.Y. (1989), 6.3.1-6.3.6. As used herein, the term hybridization or hybridizes under certain conditions is intended to describe conditions for hybridization and washes under which nucleotide sequences that are significantly identical or homologous to each other remain bound to each other. The conditions may be such that sequences, which are at least about 70%, such as at least about 80%, and such as at least about 85%, 90%, or 95% identical, remain bound to each other. Definitions of low stringency, moderate, and high stringency hybridization conditions are provided herein. Appropriate hybridization conditions can be selected by those skilled in the art with minimal experimentation as exemplified in Ausubel et al. (1995, Current Protocols in Molecular Biology, John Wiley & Sons, sections 2, 4, and 6). Additionally, stringency conditions are described in Sambrook et al. (1989, Molecular Cloning: A Laboratory Manual, 2nd ed., Cold Spring Harbor Press, chapters 7, 9, and 11). As used herein, defined conditions of low stringency are as follows. Filters containing DNA are pretreated for 6 h at 40ºC in a solution containing 35% formamide, 5x SSC, 50 mM Tris-HCl (pH 7.5), 5 mM EDTA, 0.1% PVP, 0.1% Ficoll, 1% BSA, and 500 µg / ml denatured salmon sperm DNA. Hybridizations are carried out in the same solution with the following modifications: 0.02% PVP, 0.02% Ficoll, 0.2% BSA, 100 µg / ml salmon sperm DNA, 10% (wt / vol) dextran sulfate, and 5-20x10632P-labeled probe is used. Filters are incubated in hybridization mixture for 18-20 h at 40ºC, and then washed for 1.5 h at 55ºC. In a solution containing 2x SSC, 25 mM Tris-HCl (pH 7.4), 5 mM EDTA, and 0.1% SDS. The wash solution is replaced with fresh solution and incubated an additional 1.5 h at 60ºC. Filters are blotted dry and exposed for autoradiography. As used herein, defined conditions of moderate stringency are as follows. Filters containing DNA are pretreated for 7 h at 50ºC. in a solution containing 35% formamide, 5x SSC, 50 mM Tris-HCl (pH 7.5), 5 mM EDTA, 0.1% PVP, 0.1% Ficoll, 1% BSA, and 500 µg / ml denatured salmon sperm DNA. Hybridizations are carried out in the same solution with the following modifications: 0.02% PVP, 0.02% Ficoll, 0.2% BSA, 100 µg / ml salmon sperm DNA, 10% (wt / vol) dextran sulfate, and 5-20x10632P-labeled probe is used. Filters are incubated in hybridization mixture for 30 h at 50ºC, and then washed for 1.5 h at 55ºC. In a solution containing 2x SSC, 25 mM Tris-HCl (pH 7.4), 5 mM EDTA, and 0.1% SDS. The wash solution is replaced with fresh solution and incubated an additional 1.5 h at 60ºC. Filters are blotted dry and exposed for autoradiography. As used herein, defined conditions of high stringency are as follows. Prehybridization of filters containing DNA is carried out for 8 h to overnight at 65ºC in buffer composed of 6x SSC, 50 mM Tris-HCl (pH 7.5), 1 mM EDTA, 0.02% PVP, 0.02% Ficoll, 0.02% BSA, and 500 µg / ml denatured salmon sperm DNA. Filters are hybridized for 48 h at 65ºC in the prehybridization mixture containing 100 µg / ml denatured salmon sperm DNA and 5-20x106 cpm of32P-labeled probe. Washing of filters is done at 37ºC for 1 h in a solution containing 2x SSC, 0.01% PVP, 0.01% Ficoll, and 0.01% BSA. This is followed by a wash in 0.1x SSC at 50ºC for 45 minutes. Other conditions of low, moderate, and high stringency well known in the art (e.g., as employed for cross-species hybridizations) may be used if the above conditions are inappropriate (e.g., as employed for cross-species hybridizations). A detection kit for nucleic acid sequences encoding a polypeptide of the invention may include primers and / or probes specific for nucleic acid sequences encoding the polypeptide, and an associated protocol to use the primers and / or probes to detect nucleic acid sequences encoding the polypeptide in a sample. Such detection kits may be used to determine whether a plant, organism, microorganism or cell has been modified, i.e., transformed with a sequence encoding the polypeptide. To test a function of variant DNA sequences according to an embodiment herein, the sequence of interest is operably linked to a selectable or screenable marker gene and expression of said reporter gene is tested in transient expression assays, for example, with microorganisms or with protoplasts or in stably transformed plants. The invention also relates to derivatives of the concretely disclosed or derivable nucleic acid sequences. Thus, further nucleic acid sequences according to the invention can be derived from the sequences specifically disclosed herein and can differ from it by one or more, like 1 to 20, in particular 1 to 15 or 5 to 10 additions, substitutions, insertions or deletions of one or several (like for example 1 to 10) nucleotides, and furthermore code for polypeptides with the desired profile of properties. The invention also encompasses nucleic acid sequences that comprise so-called silent mutations or have been altered, in comparison with a concretely stated sequence, according to the codon usage of a special original or host organism. According to a particular embodiment of the invention variant nucleic acids may be prepared in order to adapt its nucleotide sequence to a specific expression system. For example, bacterial expression systems are known to more efficiently express polypeptides if amino acids are encoded by particular codons. Due to the degeneracy of the genetic code, more than one codon may encode the same amino acid sequence, multiple nucleic acid sequences can code for the same protein or polypeptide, all these DNA sequences being encompassed by an embodiment herein. Where appropriate, the nucleic acid sequences encoding the polypeptides described herein may be optimized for increased expression in the host cell. For example, nucleic acids of an embodiment herein may be synthesized using codons particular to a host for improved expression. The invention also encompasses naturally occurring variants, e.g. splicing variants or allelic variants, of the sequences described therein. Allelic variants may have at least 60 % homology at the level of the derived amino acid, particularly at least 80 % homology, quite especially particularly at least 90 % homology over the entire sequence range (regarding homology at the amino acid level, reference should be made to the details given above for the polypeptides). Advantageously, the homologies can be higher over partial regions of the sequences. The invention also relates to sequences that can be obtained by conservative nucleotide substitutions (i.e. as a result thereof the amino acid in question is replaced by an amino acid of the same charge, size, polarity and / or solubility). The invention also relates to the molecules derived from the concretely disclosed nucleic acids by sequence polymorphisms. Such genetic polymorphisms may exist in cells from different populations or within a population due to natural allelic variation. Allelic variants may also include functional equivalents. These natural variations usually produce a variance of 1 to 5 % in the nucleotide sequence of a gene. Said polymorphisms may lead to changes in the amino acid sequence of the polypeptides disclosed herein. Allelic variants may also include functional equivalents. Furthermore, derivatives are also to be understood to be homologs of the nucleic acid sequences according to the invention, for example animal, plant, fungal or bacterial homologs, shortened sequences, single-stranded DNA or RNA of the coding and noncoding DNA sequence. For example, homologs have, at the DNA level, a homology of at least 40 %, particularly of at least 60 %, especially particularly of at least 70 %, quite especially particularly of at least 80 % over the entire DNA region given in a sequence specifically disclosed herein. Moreover, derivatives are to be understood to be, for example, fusions with promoters. The promoters that are added to the stated nucleotide sequences can be modified by at least one nucleotide exchange, at least one insertion, inversion and / or deletion, though without impairing the functionality or efficacy of the promoters. Moreover, the efficacy of the promoters can be increased by altering their sequence or can be exchanged completely with more effective promoters even of organisms of a different genus. 3. Constructs for expressing polypeptides of the invention “Expression of a gene” encompasses “heterologous expression” and “over- expression” and involves transcription of the gene and translation of the mRNA into a protein. Overexpression refers to the production of the gene product as measured by levels of mRNA, polypeptide and / or enzyme activity in transgenic cells or organisms that exceeds levels of production in non-transformed cells or organisms of a similar genetic background. “Expression vector” as used herein means a nucleic acid molecule engineered using molecular biology methods and recombinant DNA technology for delivery of foreign or exogenous DNA into a host cell. The expression vector typically includes sequences required for proper transcription of the nucleotide sequence. The coding region usually codes for a protein of interest but may also code for an RNA, e.g., an antisense RNA, siRNA and the like. An “expression vector” as used herein includes any linear or circular recombinant vector including but not limited to viral vectors, bacteriophages and plasmids. The skilled person is capable of selecting a suitable vector according to the expression system. In one embodiment, the expression vector includes the nucleic acid of an embodiment herein operably linked to at least one “regulatory sequence”, which controls transcription, translation, initiation and termination, such as a transcriptional promoter, operator or enhancer, or an mRNA ribosomal binding site and, optionally, including at least one selection marker. Nucleotide sequences are “operably linked” when the regulatory sequence functionally relates to the nucleic acid of an embodiment herein. An “expression system” as used herein encompasses any combination of nucleic acid molecules required for the expression of one, or the co-expression of two or more polypeptides either in vivo of a given expression host, or in vitro. The respective coding sequences may either be located on a single nucleic acid molecule or vector, as for example a vector containing multiple cloning sites, or on a polycistronic nucleic acid, or may be distributed over two or more physically distinct vectors. As a particular example there may be mentioned an operon comprising a promotor sequence, one or more operator sequences and one or more structural genes each encoding an enzyme as described herein As used herein, the terms "amplifying" and "amplification" refer to the use of any suitable amplification methodology for generating or detecting recombinant of naturally expressed nucleic acid, as described in detail, below. For example, the invention provides methods and reagents (e.g., specific degenerate oligonucleotide primer pairs, oligo dT primer) for amplifying (e.g., by polymerase chain reaction, PCR) naturally expressed (e.g., genomic DNA or mRNA) or recombinant (e.g., cDNA) nucleic acids of the invention in vivo, ex vivo or in vitro. “Regulatory sequence” refers to a nucleic acid sequence that determines expression level of the nucleic acid sequences of an embodiment herein and is capable of regulating the rate of transcription of the nucleic acid sequence operably linked to the regulatory sequence. Regulatory sequences comprise promoters, enhancers, transcription factors, promoter elements and the like. A “promoter”, a “nucleic acid with promoter activity” or a “promoter sequence” is understood as meaning, in accordance with the invention, a nucleic acid which, when functionally linked to a nucleic acid to be transcribed, regulates the transcription of said nucleic acid. “Promoter” in particular refers to a nucleic acid sequence that controls the expression of a coding sequence by providing a binding site for RNA polymerase and other factors required for proper transcription including without limitation transcription factor binding sites, repressor and activator protein binding sites. The meaning of the term promoter also includes the term “promoter regulatory sequence”. Promoter regulatory sequences may include upstream and downstream elements that may influences transcription, RNA processing or stability of the associated coding nucleic acid sequence. Promoters include naturally-derived and synthetic sequences. The coding nucleic acid sequences is usually located downstream of the promoter with respect to the direction of the transcription starting at the transcription initiation site. In this context, a “functional” or “operative” linkage is understood as meaning for example the sequential arrangement of one of the nucleic acids with a regulatory sequence. For example the sequence with promoter activity and of a nucleic acid sequence to be transcribed and optionally further regulatory elements, for example nucleic acid sequences which ensure the transcription of nucleic acids, and for example a terminator, are linked in such a way that each of the regulatory elements can perform its function upon transcription of the nucleic acid sequence. This does not necessarily require a direct linkage in the chemical sense. Genetic control sequences, for example enhancer sequences, can even exert their function on the target sequence from more remote positions or even from other DNA molecules. Preferred arrangements are those in which the nucleic acid sequence to be transcribed is positioned behind (i.e. at the 3’- end of) the promoter sequence so that the two sequences are joined together covalently. The distance between the promoter sequence and the nucleic acid sequence to be expressed recombinantly can be smaller than 200 base pairs, or smaller than 100 base pairs or smaller than 50 base pairs. In addition to promoters and terminator, the following may be mentioned as examples of other regulatory elements: targeting sequences, enhancers, polyadenylation signals, selectable markers, amplification signals, replication origins and the like. Suitable regulatory sequences are described, for example, in Goeddel, Gene Expression Technology: Methods in Enzymology 185, Academic Press, San Diego, CA (1990). The term “constitutive promoter” refers to an unregulated promoter that allows for continual transcription of the nucleic acid sequence it is operably linked to. As used herein, the term “operably linked” refers to a linkage of polynucleotide elements in a functional relationship. A nucleic acid is “operably linked” when it is placed into a functional relationship with another nucleic acid sequence. For instance, a promoter, or rather a transcription regulatory sequence, is operably linked to a coding sequence if it affects the transcription of the coding sequence. Operably linked means that the DNA sequences being linked are typically contiguous. The nucleotide sequence associated with the promoter sequence may be of homologous or heterologous origin with respect to the plant to be transformed. The sequence also may be entirely or partially synthetic. Regardless of the origin, the nucleic acid sequence associated with the promoter sequence will be expressed or silenced in accordance with promoter properties to which it is linked after binding to the polypeptide of an embodiment herein. The associated nucleic acid may code for a protein that is desired to be expressed or suppressed throughout the organism at all times or, alternatively, at a specific time or in specific tissues, cells, or cell compartment. Such nucleotide sequences particularly encode proteins conferring desirable phenotypic traits to the host cells or organism altered or transformed therewith. More particularly, the associated nucleotide sequence leads to the production of the product or products of interest as herein defined in the cell or organism. Particularly, the nucleotide sequence encodes a polypeptide having an enzyme activity as herein defined. The nucleotide sequence as described herein above may be part of an “expression cassette”. The terms “expression cassette” and “expression construct” are used synonymously. The (particularly recombinant) expression construct contains a nucleotide sequence which encodes a polypeptide according to the invention and which is under genetic control of regulatory nucleic acid sequences. In a process applied according to the invention, the expression cassette may be part of an “expression vector”, in particular of a recombinant expression vector. An “expression unit” is understood as meaning, in accordance with the invention, a nucleic acid with expression activity which comprises a promoter as defined herein and, after functional linkage with a nucleic acid to be expressed or a gene, regulates the expression, i.e. the transcription and the translation of said nucleic acid or said gene. It is therefore in this connection also referred to as a “regulatory nucleic acid sequence”. In addition to the promoter, other regulatory elements, for example enhancers, can also be present. An “expression cassette” or “expression construct” is understood as meaning, in accordance with the invention, an expression unit which is functionally linked to the nucleic acid to be expressed or the gene to be expressed. In contrast to an expression unit, an expression cassette therefore comprises not only nucleic acid sequences which regulate transcription and translation, but also the nucleic acid sequences that are to be expressed as protein as a result of transcription and translation. The terms “expression” or “overexpression” describe, in the context of the invention, the production or increase in intracellular activity of one or more polypeptides in a microorganism, which are encoded by the corresponding DNA. To this end, it is possible for example to introduce a gene into an organism, replace an existing gene with another gene, increase the copy number of the gene(s), use a strong promoter or use a gene which encodes for a corresponding polypeptide with a high activity; optionally, these measures can be combined. Particularly such constructs according to the invention comprise a promoter 5’- upstream of the respective coding sequence and a terminator sequence 3’-downstream and optionally other usual regulatory elements, in each case in operative linkage with the coding sequence. Nucleic acid constructs according to the invention comprise in particular a sequence coding for a polypeptide for example derived from the amino acid related SEQ ID NOs as described therein or the reverse complement thereof, or derivatives and homologs thereof and which have been linked operatively or functionally with one or more regulatory signals, advantageously for controlling, for example increasing, gene expression. In addition to these regulatory sequences, the natural regulation of these sequences may still be present before the actual structural genes and optionally may have been genetically modified so that the natural regulation has been switched off and expression of the genes has been enhanced. The nucleic acid construct may, however, also be of simpler construction, i.e. no additional regulatory signals have been inserted before the coding sequence and the natural promoter, with its regulation, has not been removed. Instead, the natural regulatory sequence is mutated such that regulation no longer takes place and the gene expression is increased. A preferred nucleic acid construct advantageously also comprises one or more of the already mentioned “enhancer” sequences in functional linkage with the promoter, which sequences make possible an enhanced expression of the nucleic acid sequence. Additional advantageous sequences may also be inserted at the 3’-end of the DNA sequences, such as further regulatory elements or terminators. One or more copies of the nucleic acids according to the invention may be present in a construct. In the construct, other markers, such as genes which complement auxotrophisms or antibiotic resistances, may also optionally be present so as to select for the construct. Examples of suitable regulatory sequences are present in promoters such as cos, tac, trp, tet, trp-tet, lpp, lac, lpp-lac, lacIq, T7, T5, T3, gal, trc, ara, rhaP (rhaPBAD)SP6, lambda-PR or in the lambda-PL promoter, and these are advantageously employed in Gram-negative bacteria. Further advantageous regulatory sequences are present for example in the Gram-positive promoters amy and SPO2, in the yeast or fungal promoters ADC1, MFalpha, AC, P-60, CYC1, GAPDH, TEF, rp28, ADH. Artificial promoters may also be used for regulation. For expression in a host organism, the nucleic acid construct is inserted advantageously into a vector such as, for example, a plasmid or a phage, which makes possible optimal expression of the genes in the host. Vectors are also understood as meaning, in addition to plasmids and phages, all the other vectors which are known to the skilled worker, that is to say for example viruses such as SV40, CMV, baculovirus and adenovirus, transposons, IS elements, phasmids, cosmids and linear or circular DNA or artificial chromosomes. These vectors are capable of replicating autonomously in the host organism or else chromosomally. These vectors are a further development of the invention. Binary or cpo-integration vectors are also applicable. Suitable plasmids are, for example, in E.coli pLG338, pACYC184, pBR322, pUC18, pUC19, pKC30, pRep4, pHS1, pKK223-3, pDHE19.2, pHS2, pPLc236, pMBL24, pLG200, pUR290, pIN-III113-B1, λgt11 or pBdCI, in Streptomyces pIJ101, pIJ364, pIJ702 or pIJ361, in Bacillus pUB110, pC194 or pBD214, in Corynebacterium pSA77 or pAJ667, in fungi pALS1, pIL2 or pBB116, in yeasts 2alphaM, pAG-1, YEp6, YEp13 or pEMBLYe23 or in plants pLGV23, pGHlac+, pBIN19, pAK2004 or pDH51. The abovementioned plasmids are a small selection of the plasmids which are possible. Further plasmids are well known to the skilled worker and can be found for example in the book Cloning Vectors (Eds. Pouwels P. H. et al. Elsevier, Amsterdam-New York- Oxford, 1985, ISBN 0444904018). In a further development of the vector, the vector which comprises the nucleic acid construct according to the invention or the nucleic acid according to the invention can advantageously also be introduced into the microorganisms in the form of a linear DNA and integrated into the host organism’s genome via heterologous or homologous recombination. This linear DNA can consist of a linearized vector such as a plasmid or only of the nucleic acid construct or the nucleic acid according to the invention. For optimal expression of heterologous genes in organisms, it is advantageous to modify the nucleic acid sequences to match the specific “codon usage” used in the organism. The “codon usage” can be determined readily by computer evaluations of other, known genes of the organism in question. An expression cassette according to the invention is generated by fusing a suitable promoter to a suitable coding nucleotide sequence and a terminator or polyadenylation signal. Customary recombination and cloning techniques are used for this purpose, as are described, for example, in T. Maniatis, E.F. Fritsch and J. Sambrook, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (1989) and in T.J. Silhavy, M.L. Berman and L.W. Enquist, Experiments with Gene Fusions, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (1984) and in Ausubel, F.M. et al., Current Protocols in Molecular Biology, Greene Publishing Assoc. and Wiley Interscience (1987). For expression in a suitable host organism, the recombinant nucleic acid construct or gene construct is advantageously inserted into a host-specific vector which makes possible optimal expression of the genes in the host. Vectors are well known to the skilled worker and can be found for example in “cloning vectors” (Pouwels P. H. et al., Ed., Elsevier, Amsterdam-New York-Oxford, 1985). An alternative embodiment of an embodiment herein provides a method to “alter gene expression” in a host cell. For instance, the polynucleotide of an embodiment herein may be enhanced or overexpressed or induced in certain contexts (e.g. upon exposure to certain temperatures or culture conditions) in a host cell or host organism. Alteration of expression of a polynucleotide provided herein may also result in ectopic expression which is a different expression pattern in an altered and in a control or wild-type organism. Alteration of expression occurs from interactions of polypeptide of an embodiment herein with exogenous or endogenous modulators, or as a result of chemical modification of the polypeptide. The term also refers to an altered expression pattern of the polynucleotide of an embodiment herein which is altered below the detection level or completely suppressed activity. In one embodiment, provided herein is also an isolated, recombinant or synthetic polynucleotide encoding a polypeptide or variant polypeptide provided herein. In one embodiment, several polypeptide encoding nucleic acid sequences are co-expressed in a single host, particularly under control of different promoters. In another embodiment, several polypeptide encoding nucleic acid sequences can be present on a single transformation vector or be co-transformed at the same time using separate vectors and selecting transformants comprising both chimeric genes. Similarly, one or polypeptide encoding genes may be expressed in a single plant, cell, microorganism or organism together with other chimeric genes. 4. Generation of functional mutants A person skilled in the art is familiar with processes for generating functional mutants of enzymes according to the invention. Depending on the technique used, a person skilled in the art can introduce entirely random or else more targeted mutations into genes or else noncoding nucleic acid sections (which are, for example, important for regulating expression) and subsequently construct the gene libraries. The methods of molecular biology which are required for this purpose are known to a person skilled in the art and described, for example, in Sambrook and Russell, Molecular Cloning. 3rd ed., Cold Spring Harbor Laboratory Press 2001. Methods of modifying genes and thus of modifying the proteins encoded by them have long been known to a person skilled in the art, such as, for example, • site-specific mutagenesis, where individual or multiple nucleotides of a gene are replaced in a targeted manner (Trower MK (Ed.) 1996; In vitro mutagenesis protocols. Humana Press, New Jersey), • saturation mutagenesis, where a codon for any amino acid may be replaced or added at any gene locus (Kegler-Ebo DM, Docktor CM, DiMaio D (1994) Nucleic Acids Res 22:1593; Barettino D, Feigenbutz M, Valcárel R, Stunnenberg HG (1994) Nucleic Acids Res 22:541; Barik S (1995) Mol. Biotechnol.3:1), • error-prone polymerase chain reaction (error-prone PCR), where nucleotide sequences are mutated by erroneously working DNA polymerases (Eckert KA, Kunkel TA (1990) Nucleic Acids Res.18:3739); • the SeSaM method (sequence saturation method), where preferential substitutions are prevented by the polymerase. Schenk et al., Biospektrum, vol.3, 2006, 277-279 • the passaging of genes in mutator strains, in which, for example, an increased mutation rate of nucleotide sequences takes place on account of defective DNA repair mechanisms (Greener A, Callahan M, Jerpseth B (1996) An efficient random mutagenesis technique using an E. coli mutator strain. In: Trower MK (Ed.) In vitro mutagenesis protocols. Humana Press, New Jersey), or • DNA shuffling, where a pool of closely related genes is formed and digested and the fragments are used as templates for a polymerase chain reaction, in which mosaic genes of full length are finally produced by repeated strand separation and reannealing (Stemmer WPC (1994) Nature 370:389; Stemmer WPC (1994) Proc. Natl. Acad. Sci. USA 91:10747). Using “directed evolution” (described, inter alia, in Reetz MT and Jaeger K-E (1999), Topics Curr. Chem.200:31; Zhao H, Moore JC, Volkov AA, Arnold FH (1999), Methods for optimizing industrial enzymes by directed evolution, In: Demain AL, Davies JE (Ed.) Manual of industrial microbiology and biotechnology. American Society for Microbiology), a person skilled in the art can also generate functional mutants in a selective manner and also on a large scale. Here, in a first step, gene libraries of the respective proteins are initially produced, it being possible to employ, for example, the methods indicated hereinabove. The gene libraries are expressed in a suitable manner, for example by bacteria or by phage display systems. The relevant genes of host organisms that express functional mutants with properties which largely correspond to the desired properties may be subjected to a further round of mutation. The steps of mutation and selection or screening may be repeated iteratively until the functional mutants present possess the desired properties in an adequate measure. As a result of this iterative procedure, a limited number of mutations, such as, for example, 1, 2, 3, 4 or 5 mutations, may be performed stepwise, and assessed and selected for their effect on the respective enzyme property. Then, the selected mutant may be subjected to a further mutation step in the same manner. The number of individual mutants to be studied may be significantly decreased thereby. The results according to the invention also provide important information with respect to structure and sequence of the respective enzymes, which are required for generating, in a targeted fashion, further enzymes with desired modified properties. In particular, it is possible to define so-called “hot spots”, i.e. sequence segments which are potentially suitable for modifying an enzyme property via the introduction of targeted mutations. Likewise, information is derivable in respect of amino acid sequence positions in whose surroundings mutations may be carried out which will presumably have little effect on the enzymatic activity and which may be referred to as potential “silent mutations”. 5. Microorganisms Depending on context, the term "microorganism" means the starting (wild-type) microorganism or a genetically modified, recombinant microorganism, or both. Using the vectors according to the process of the invention, recombinant microorganisms can be produced, which for example have been transformed with at least one vector according to the invention and can be used for producing the polypeptides according the process of the invention. Advantageously, the recombinant constructs described above are introduced into a suitable host system and expressed. Preferably, common cloning and transfection methods known by a person skilled in the art are used, for example coprecipitation, protoplast fusion, electroporation, retroviral transfection and the like, to bring about expression of the stated nucleic acids in the respective expression system. Suitable systems are described for example in Current Protocols in Molecular Biology, F. Ausubel et al., Publ., Wiley Interscience, New York 1997, or Sambrook et al. Molecular Cloning: A Laboratory Manual. 2nd ed., Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1989. A review of bacterial expression systems for the heterologous expression of proteins is also provided for example by Terpe, K. Appl. Microbiol. Biotechnol. (2006) 72: 211-222. In principle, all prokaryotic or eukaryotic organisms may come into consideration as recombinant host organisms for the nucleic acid according to the invention or the nucleic acid construct. Advantageously, microorganisms such as bacteria, fungi or yeasts are used as host organisms. Advantageously, Gram-positive or Gram-negative bacteria are used, preferably bacteria of the families Enterobacteriaceae, Pseudomonadaceae, Rhizobiaceae, Streptomycetaceae or Nocardiaceae, especially preferably bacteria of the genera Escherichia, Pseudomonas, Streptomyces, Nocardia, Burkholderia, Salmonella, Agrobacterium, Clostridium, Saccharomyces, Rhodobacter or Rhodococcus. The genus Escherichia and Saccharomyces and the species Escherichia coli and Saccharomyces cerevisiae are quite especially preferred. Further advantageous bacteria can be found, moreover, in the group of alpha-proteobacteria, beta- proteobacteria or gamma-proteobacteria. The host organism or the host organisms according to the invention preferably contain at least one of the nucleic acid sequences, nucleic acid constructs or vectors of this invention, which code for the enzymes used in the process of the invention according to the above definition. Such organisms are grown or cultured in a manner known by a person skilled in the art, depending on the host organism. Microorganisms are as a rule grown in a liquid medium, which contains a carbon source generally in the form of sugars, a nitrogen source generally in the form of organic nitrogen sources such as yeast extract or salts such as ammonium sulfate, trace elements such as iron, manganese, magnesium salts and optionally vitamins, at temperatures between 0°C and 100°C, preferably between 10°C and 60°C with oxygen aeration. The pH of the liquid nutrient medium can be maintained at a fixed value, i.e. during growing it may or may not be regulated. Culture can be batchwise, semi- batchwise or continuous. Nutrients can be supplied at the start of fermentation or can be replenished semi-continuously or continuously. 6. Enzyme immobilization In the process described herein, the enzymes according to the process of the invention can be used free or immobilized. An immobilized enzyme is to be understood as an enzyme that is fixed to an inert support. Suitable support materials and the enzymes immobilized thereon are known from EP-A-1149849, EP-A-1069183 and DE- OS 100193773 and from the literature references cited therein. Regarding this, full reference is made to the disclosure of these documents. Suitable support materials include for example clays, clay minerals, such as kaolinite, diatomaceous earth, perlite, silicon dioxide, aluminium oxide, sodium carbonate, calcium carbonate, cellulose powder, anion exchanger materials, synthetic polymers, such as polystyrene, acrylic resins, phenol-formaldehyde resins, polyurethanes and polyolefins, such as polyethylene and polypropylene. For preparing the supported enzymes, the support materials are usually used in a finely-divided, particulate form, with porous forms being preferred. The particle size of the support material is usually not more than 5 mm, especially not more than 2 mm (particle-size distribution curve). Support materials are for example Ca-alginate, and carrageenan. Enzymes as well as cells can also be crosslinked directly with glutaraldehyde (crosslinking to CLEAs). Corresponding and further methods of immobilization are described for example in J. Lalonde and A. Margolin "Immobilization of Enzymes" and in K. Drauz and H. Waldmann, Enzyme Catalysis in Organic Synthesis 2002, Vol.III, 991-1032, Wiley-VCH, Weinheim. The invention will now be explained in more detail by means of the following, non- limiting examples. 7. Aroma Compositions In an embodiment, the presently claimed invention relates to a composition comprising at least one compound of anyone of the above embodiments 3 to 5 or a combination of compounds of embodiment 27 and (i) at least one aroma chemical (X) other than the compound of anyone of the above embodiments 3 to 5 or a combination of compounds of embodiment 27 or (ii) at least one non-aroma chemical carrier, or (iii) both of (i) and (ii). Preferably in this embodiment, the composition comprising compound (I), wherein the amount of at least one compound (I), is in the range of ≥ 0.01 wt.% to ≤ 70.0 wt.%, based on the total weight of the composition. Preferably, the composition is an aroma composition, more preferable a fragrance composition. a) Aroma chemicals different from the compounds of anyone of the above embodiments 3 to 5 or a combination of compounds of embodiment 27 In one embodiment, the mixture comprises one aroma chemical which is different from the compound of anyone of the above embodiments 3 to 5 or a combination of compounds of embodiment 27; said aroma chemical is also referred to as aroma chemical (X). By virtue of their physical properties, the compounds prepared according to the present invention are well combinable with aroma chemicals which are different therefrom and other customary ingredients in aroma compositions, in particular fragrance compositions. This allows, e.g., the creation of aroma compositions (preferably fragrance compositions) which have novel advantageous sensory profiles. For example, the compounds can provide a booster effect for other aroma chemicals (such as fragrances). The aroma chemical (X) is preferably selected from the group consisting of: Geranyl acetate, alpha-hexylcinnamaldehyde, 2 phenoxyethyl isobutyrate, dihydromyrcenol, methyl dihydrojasmonate , 4,6,6,7,8,8 hexamethyl-1,3,4,6,7,8-hexa- hydro¬cyclopenta[g]benzopyran, tetrahydrolinalool, ethyllinalool, benzyl salicylate, 2 methyl-3-(4-tert-butylphenyl)propanal, cinnamyl alcohol, 4,7 methano-3a,4,5,6,7,7a- hexahydro-5 indenyl acetate and / or 4,7 methano-3a,4,5,6,7,7a-hexahydro-6-indenyl acetate, citronellol, citronellyl acetate, tetrahydrogeraniol, vanillin, linalyl acetate, styryl acetate, octahydro-2,3,8,8-tetramethyl-2-acetonaphthone and / or 2 acetyl-1,2,3,4,6,7,8- octahydro-2,3,8,8-tetramethylnaphthalene, hexyl salicylate, 4 tert-butylcyclohexyl acetate, 2-tert-butylcyclohexyl acetate, alpha-ionone, alpha-methylionone, alpha-iso- methylionone, coumarin, terpinyl acetate, 2 phenylethyl alcohol, 4-(4-hydroxy-4- methylpentyl)-3-cyclohexene-carboxaldehyde, alpha-amylcinnamaldehyde, ethylene brassylate, (E) and / or (Z)-3-methylcyclopentadec-5 enone, 15-pentadec-11-enolide and / or 15-pentadec-12-enolide, 15-cyclo¬pentadecanolide, 1-(5,6,7,8-tetrahydro- 3,5,5,6,8,8-hexamethyl-2-naphthalenyl)ethanone, 2-isobutyl-4-methyltetrahydro-2H pyran-4-ol, 2-ethyl-4-(2,2,3-trimethyl-3-cyclopenten-1-yl)-2-buten-1-ol, cis-3-hexenyl acetate, trans-3-hexenyl acetate, trans-2 / cis-6-nonadienol, 2,4-dimethyl-3- cyclohexenecarboxaldehyde, 2,4,4,7-tetramethyloct-6-en-3-one, 2,6-dimethyl-5-hepten- 1-al, borneol, 3 (3 isopropylphenyl)butanal, 2-methyl-3-(3,4-methylenedioxyphenyl)- propanal, 3-(4-ethylphenyl)-2,2-dimethylpropanal, 7-methyl-2H 1,5-benzodioxepin- 3(4H)-one, 3,3,5-trimethylcyclohexyl acetate, 2,5,5 trimethyl-1,2,3,4,4a,5,6,7- octahydronaphthalen-2-ol, 3-(4-tert-butylphenyl)-propanal, ethyl 2-methylpentanoate, ethoxymethoxycyclododecane, 2,4-dimethyl-4,4a,5,9b-tetrahydroindeno[1,2- d][1,3]dioxine, (2-tert-butylcyclohexyl) acetate and 3-[5,5,6-trimethylbicyclo[2.2.1]hept- 2-yl]cyclohexan-1-ol. In a preferred embodiment, the at least one aroma chemical (X) is selected from the group consisting of methyl benzoate, benzyl acetate, geranyl acetate, 2-isobutyl-4- methyltetrahydro-2H-pyran-4-ol, linalool, 2-isobutyl-4-methyltetrahydro-2H-pyran-4-ol and methyl benzoate. In another preferred embodiment, the at least one aroma chemical (X) is selected from the group consisting of ethylvanillin, vanillin, 2,5-dimethyl-4-hydroxy-2H-furan-3-one (furaneol) and 3-hydroxy-2-methyl-4H-pyran-4-one (maltol). Further aroma chemicals with which the compound of formula can be combined to give a composition according to the presently claimed invention can be found, e.g., in S. Arctander, Perfume and Flavor Chemicals, Vol. I and II, Montclair, N. J., 1969, self- published or K. Bauer, D. Garbe and H. Surburg, Common Fragrance and Flavor Materials, 4th Ed., Wiley- VCH, Weinheim 2001. Specifically, mention may be made of: - extracts from natural raw materials such as essential oils, concretes, absolutes, resins, resinoids, balsams, tinctures such as e.g. - ambergris tincture; amyris oil; angelica seed oil; angelica root oil; aniseed oil; valerian oil; basil oil; tree moss absolute; bay oil; mugwort oil; benzoin resin; bergamot oil; beeswax absolute; birch tar oil; bitter almond oil; savory oil; buchu leaf oil; cabreuva oil; cade oil; calmus oil; camphor oil; cananga oil; cardamom oil; cascarilla oil; cassia oil; cassia absolute; castoreum absolute; cedar leaf oil; cedar wood oil; cistus oil; citronella oil; lemon oil; copaiba balsam; copaiba balsam oil; coriander oil; costus root oil; cumin oil; cypress oil; davana oil; dill weed oil; dill seed oil; Eau de brouts absolute; oak moss absolute; elemi oil; tarragon oil; eucalyptus citriodora oil; eucalyptus oil; fennel oil; pine needle oil; galbanum oil; galbanum resin; geranium oil; grapefruit oil; guaiacwood oil; gurjun balsam; gurjun balsam oil; helichrysum absolute; helichrysum oil; ginger oil; iris root absolute; iris root oil; jasmine absolute; calmus oil; camomile oil blue; roman camomile oil; carrot seed oil; cascarilla oil; pine needle oil; spearmint oil; caraway oil; labdanum oil; labdanum absolute; labdanum resin; lavandin absolute; lavandin oil; lavender absolute; lavender oil; lemongrass oil; lovage oil; lime oil distilled; lime oil pressed; linalool oil; litsea cubeba oil; laurel leaf oil; mace oil; marjoram oil; mandarin oil; massoia bark oil; mimosa absolute; musk seed oil; musk tincture; clary sage oil; nutmeg oil; myrrh absolute; myrrh oil; myrtle oil; clove leaf oil; clove flower oil; neroli oil; olibanum absolute; olibanum oil; opopanax oil; orange blossom absolute; orange oil; origanum oil; palmarosa oil; patchouli oil; perilla oil; peru balsam oil; parsley leaf oil; parsley seed oil; petitgrain oil; peppermint oil; pepper oil; pimento oil; pine oil; pennyroyal oil; rose absolute; rose wood oil; rose oil; rosemary oil; Dalmatian sage oil; Spanish sage oil; sandalwood oil; celery seed oil; spike-lavender oil; star anise oil; styrax oil; tagetes oil; fir needle oil; tea tree oil; turpentine oil; thyme oil; tolubalsam; tonka absolute; tuberose absolute; vanilla extract; violet leaf absolute; verbena oil; vetiver oil; juniper berry oil; wine lees oil; wormwood oil; winter green oil; hyssop oil; civet absolute; cinnamon leaf oil; cinnamon bark oil, and fractions thereof, or ingredients isolated therefrom; - individual fragrances from the group of hydrocarbons, such as e.g. 3 carene; alpha-pinene; beta-pinene; alpha-terpinene; gamma-terpinene; p-cymene; bisabolene; camphene; caryophyllene; cedrene; farnesene; limonene; longifolene; myrcene; ocimene; valencene; (E,Z)-1,3,5-undecatriene; styrene; diphenylmethane; - aliphatic alcohols such as e.g. hexanol; octanol; 3-octanol; 2,6-dimethylheptanol; 2-methyl-2-heptanol; 2-methyl-2-octanol; (E)-2-hexenol; (E)- and (Z)-3-hexenol; 1 octen-3-ol; mixture of 3,4,5,6,6-pentamethyl-3 / 4-hepten-2-ol and 3,5,6,6- tetramethyl-4-methyleneheptan-2-ol; (E,Z)-2,6-nonadienol; 3,7-dimethyl-7- methoxyoctan-2-ol; 9-decenol; 10-undecenol; 4-methyl-3-decen-5-ol; - aliphatic aldehydes and acetals thereof such as e.g. hexanal; heptanal; octanal; nonanal; decanal; undecanal; dodecanal; tridecanal; 2-methyloctanal; 2- methylnonanal; (E)-2-hexenal; (Z)-4-heptenal; 2,6-dimethyl-5-heptenal; 10- undecenal; (E)-4-decenal; 2-dodecenal; 2,6,10-trimethyl-9-undecenal; 2,6,10 trimethyl-5,9-undecadienal; heptanal diethylacetal; 1,1-dimethoxy-2,2,5 trimethyl-4-hexene; citronellyloxyacetaldehyde; (E / Z)-1-(1-methoxypropoxy)- hex-3-ene; the aliphatic ketones and oximes thereof such as e.g.2-heptanone; 2-octanone; 3-octanone; 2-nonanone; 5-methyl-3-heptanone; 5-methyl-3 heptanone oxime; 2,4,4,7-tetramethyl-6-octen-3-one; 6-methyl-5-hepten-2-one; - aliphatic sulfur-containing compounds such as e.g. 3-methylthiohexanol; 3- methylthiohexyl acetate; 3-mercaptohexanol; 3-mercaptohexyl acetate; 3- mercaptohexyl butyrate; 3-acetylthiohexyl acetate; 1-menthene-8-thiol; - aliphatic nitriles such as e.g.2-nonenenitrile; 2-undecenenitrile; 2 tridecenenitrile; 3,12-tridecadienenitrile; 3,7-dimethyl-2,6-octadienenitrile; 3,7-dimethyl-6 octenenitrile; - esters of aliphatic carboxylic acids such as e.g. (E) and (Z)-3-hexenyl formate; ethyl acetoacetate; isoamyl acetate; hexyl acetate; 3,5,5-trimethylhexyl acetate; 3 methyl-2-butenyl acetate; (E)-2-hexenyl acetate; (E) and (Z)-3-hexenyl acetate; octyl acetate; 3-octyl acetate; 1-octen-3-yl acetate; ethyl butyrate; butyl butyrate; isoamyl butyrate; hexyl butyrate; (E) and (Z)-3-hexenyl isobutyrate; hexyl crotonate; ethyl isovalerate; ethyl 2-methylpentanoate; ethyl hexanoate; allyl hexanoate; ethyl heptanoate; allyl heptanoate; ethyl octanoate; ethyl (E,Z)- 2,4-decadienoate; methyl 2-octinate; methyl 2-noninate; allyl 2-isoamyloxy acetate; methyl-3,7-dimethyl-2,6-octadienoate; 4-methyl-2-pentyl crotonate; - acyclic terpene alcohols such as e.g. geraniol; nerol; linalool; lavandulol; nerolidol; farnesol; tetrahydrolinalool; 2,6-dimethyl-7-octen-2-ol; 2,6- dimethyloctan-2-ol; 2-methyl-6-methylene-7-octen-2-ol; 2,6-dimethyl-5,7- octadien-2-ol; 2,6-dimethyl-3,5-octadien-2 ol; 3,7-dimethyl-4,6-octadien-3-ol; 3,7-dimethyl-1,5,7-octatrien-3-ol; 2,6-dimethyl-2,5,7-octatrien-1-ol; and the formates, acetates, propionates, isobutyrates, butyrates, isovalerates, pentanoates, hexanoates, crotonates, tiglinates and 3-methyl-2 butenoates thereof; - cyclic terpene aldehydes and ketones such as e.g. geranial; neral; citronellal; 7 hydroxy-3,7-dimethyloctanal; 7 methoxy-3,7-dimethyloctanal; 2,6,10-trimethyl-9 undecenal; geranyl acetone; as well as the dimethyl and diethylacetals of geranial, neral, 7-hydroxy-3,7-dimethyloctanal; the cyclic terpene alcohols such as e.g. menthol; isopulegol; alpha-terpineol; terpine-4-ol; menthan-8-ol; menthan-1-ol; menthan-7-ol; borneol; isoborneol; linalool oxide; nopol; cedrol; ambrinol; vetiverol; guajol; and the formates, acetates, propionates, isobutyrates, butyrates, isovalerates, pentanoates, hexanoates, crotonates, tiglinates and 3- methyl-2-butenoates thereof; - cyclic terpene aldehydes and ketones such as e.g. menthone; isomenthone; 8 mercaptomenthan-3-one; carvone; camphor; fenchone; alpha-ionone; beta- ionone; alpha-n-methylionone; beta-n-methylionone; alpha-isomethylionone; beta-isomethylionone; alpha-irone; alpha-damascone; beta-damascone; beta- damascenone; delta-damascone; gamma-damascone; 1-(2,4,4-trimethyl-2- cyclohexen-1-yl)-2-buten-1-one; 1,3,4,6,7,8a-hexahydro-1,1,5,5-tetramethyl-2H- 2,4a-methano¬naphthalene-8(5H)-one; 2-methyl-4-(2,6,6-trimethyl-1- cyclohexen-1-yl)-2-butenal; nootkatone; dihydronootkatone; 4,6,8- megastigmatrien-3-one; alpha-sinensal; beta-sinensal; acetylated cedar wood oil (methyl cedryl ketone); - cyclic alcohols such as e.g. 4-tert-butylcyclohexanol; 3,3,5- trimethylcyclohexanol; 3-isocamphylcyclohexanol; 2,6,9-trimethyl-Z2,Z5,E9- cyclododecatrien-1-ol; 2-isobutyl-4-methyltetrahydro-2H-pyran-4-ol; - cycloaliphatic alcohols such as e.g. alpha-3,3-trimethylcyclohexylmethanol; 1 (4- isopropylcyclohexyl)ethanol; 2-methyl-4-(2,2,3-trimethyl-3-cyclopent-1- yl)butanol; 2-methyl-4-(2,2,3 trimethyl-3-cyclopent-1-yl)-2-buten-1-ol; 2-ethyl-4- (2,2,3-trimethyl-3 cyclopent-1-yl)-2-buten-1-ol; 3-methyl-5-(2,2,3 trimethyl-3- cyclopent-1-yl)pentan-2 ol; 3-methyl-5-(2,2,3-trimethyl-3-cyclopent-1-yl)-4- penten-2-ol; 3,3-dimethyl-5-(2,2,3-trimethyl-3-cyclopent-1-yl)-4-penten-2-ol; 1- (2,2,6-trimethylcyclohexyl)pentan-3-ol; 1-(2,2,6-trimethylcyclohexyl)hexan-3-ol; - cyclic and cycloaliphatic ethers such as e.g. cineol; cedryl methyl ether; cyclododecyl methyl ether; 1,1-dimethoxycyclododecane; (ethoxymethoxy)cyclo- dodecane; alpha-cedrene epoxide; 3a,6,6,9a- tetramethyldodecahydronaphtho[2,1-b]furan; 3a-ethyl-6,6,9a- trimethyldodecahydro-naphtho[2,1-b]furan; 1,5,9-trimethyl-13-oxabicyclo- [10.1.0]trideca-4,8-diene; rose oxide; 2-(2,4-dimethyl-3-cyclohexen-1-yl)-5- methyl-5-(1-methylpropyl)-1,3-dioxane; - cyclic and macrocyclic ketones such as e.g. 4-tert-butylcyclohexanone; 2,2,5 trimethyl-5-pentylcyclopentanone; 2-heptylcyclopentanone; 2-pentylcyclo- pentanone; 2-hydroxy-3-methyl-2-cyclopenten-1-one; 3-methyl-cis-2-penten-1- yl-2 cyclopenten-1-one; 3-methyl-2-pentyl-2-cyclopenten-1-one; 3-methyl-4- cyclopenta-decenone; 3-methyl-5-cyclopentadecenone; 3- methylcyclopentadecanone; 4-(1-ethoxyvinyl)-3,3,5,5- tetramethylcyclohexanone; 4-tert-pentylcyclohexanone; 5-cyclohexadecen-1- one; 6,7-dihydro-1,1,2,3,3-pentamethyl-4(5H)-indanone; 8-cyclo-hexadecen-1- one; 7-cyclohexadecen-1-one; (7 / 8)-cyclohexadecen-1-one; 9 cyclo- heptadecen-1-one; cyclopentadecanone; cyclohexadecanone; - cycloaliphatic aldehydes such as e.g.2,4-dimethyl-3-cyclohexenecarbaldehyde; 2 methyl-4-(2,2,6-trimethylcyclohexen-1-yl)-2-butenal; 4-(4-hydroxy-4- methylpentyl)-3 cyclohexene carbaldehyde; 4-(4-methyl-3-penten-1-yl)-3- cyclohexenecarbaldehyde; - cycloaliphatic ketones such as e.g. 1-(3,3-dimethylcyclohexyl)-4-penten-1-one; 2,2 dimethyl-1-(2,4-dimethyl-3-cyclohexen-1-yl)-1-propanone; 1-(5,5-dimethyl-1 cyclo-hexen-1-yl)-4-penten-1-one; 2,3,8,8-tetramethyl-1,2,3,4,5,6,7,8- octahydro-2-naphthalenyl methyl ketone; methyl 2,6,10-trimethyl-2,5,9- cyclododecatrienyl ketone; tert-butyl (2,4-dimethyl-3-cyclohexen-1-yl) ketone; - esters of cyclic alcohols such as e.g. 2-tert-butylcyclohexyl acetate; 4-tert- butylcyclohexyl acetate; 2-tert-pentylcyclohexyl acetate; 4-tert-pentylcyclohexyl acetate; 3,3,5-trimethylcyclohexyl acetate; decahydro-2-naphthyl acetate; 2- cyclopentylcyclopentyl crotonate; 3-pentyltetrahydro-2H-pyran-4-yl acetate; decahydro-2,5,5,8a-tetramethyl-2-naphthyl acetate; 4,7-methano-3a,4,5,6,7,7a- hexahydro-5 or 6-indenyl acetate; 4,7-methano-3a,4,5,6,7,7a-hexahydro-5 or 6 indenyl propionate; 4,7-methano-3a,4,5,6,7,7a-hexahydro-5 or 6-indenyl isobutyrate; 4,7 methanooctahydro-5 or 6-indenyl acetate; - esters of cycloaliphatic alcohols such as e.g.1-cyclohexylethyl crotonate; - esters of cycloaliphatic carboxylic acids such as e.g. allyl 3-cyclohexylpropionate; allyl cyclohexyloxyacetate; cis and trans-methyl dihydrojasmonate; cis and trans- methyl jasmonate; methyl 2-hexyl-3-oxocyclopentanecarboxylate; ethyl 2-ethyl- 6,6 dimethyl-2-cyclohexenecarboxylate; ethyl 2,3,6,6-tetramethyl-2 cyclohexene- carboxylate; ethyl 2-methyl-1,3-dioxolane-2-acetate; - araliphatic alcohols such as e.g. benzyl alcohol; 1-phenylethyl alcohol, 2 phenylethyl alcohol, 3-phenylpropanol; 2-phenylpropanol; 2-phenoxyethanol; 2,2-dimethyl-3-phenylpropanol; 2,2-dimethyl-3-(3-methylphenyl)propanol; 1,1- dimethyl-2 phenylethyl alcohol; 1,1-dimethyl-3-phenylpropanol; 1-ethyl-1-methyl- 3-phenylpropanol; 2-methyl-5-phenylpentanol; 3-methyl-5-phenylpentanol; 3- phenyl-2-propen-1-ol; 4-methoxy¬benzyl alcohol; 1-(4-isopropylphenyl)ethanol; - esters of araliphatic alcohols and aliphatic carboxylic acids such as e.g. benzyl acetate; benzyl propionate; benzyl isobutyrate; benzyl isovalerate; 2-phenylethyl acetate; 2-phenylethyl propionate; 2-phenylethyl isobutyrate; 2 phenylethyl isovalerate; 1 phenylethyl acetate; alpha-trichloromethylbenzyl acetate; alpha,alpha-dimethylphenylethyl acetate; alpha,alpha-dimethylphenylethyl butyrate; cinnamyl acetate; 2-phenoxyethyl isobutyrate; 4-methoxybenzyl acetate; - araliphatic ethers such as e.g.2-phenylethyl methyl ether; 2 phenylethyl isoamyl ether; 2-phenylethyl 1-ethoxyethyl ether; phenylacetaldehyde dimethyl acetal; phenylacetaldehyde diethyl acetal; hydratropaaldehyde dimethyl acetal; phenylacetaldehyde glycerol acetal; 2,4,6-trimethyl-4-phenyl-1,3-dioxane; 4,4a,5,9b-tetrahydroindeno[1,2-d]-m-dioxine; 4,4a,5,9b-tetrahydro-2,4- dimethylindeno[1,2-d]-m dioxine; - aromatic and araliphatic aldehydes such as e.g. benzaldehyde; phenylacetaldehyde; 3-phenylpropanal; hydratropaaldehyde; 4- methylbenzaldehyde; 4 methylphenylacetaldehyde; 3-(4-ethylphenyl)-2,2- dimethylpropanal; 2-methyl-3-(4-isopropylphenyl)propanal; 2-methyl-3-(4-tert- butylphenyl)propanal; 2-methyl-3-(4-isobutylphenyl)propanal; 3-(4-tert- butylphenyl)propanal; cinnamaldehyde; alpha-butylcinnamaldehyde; alpha- amylcinnamaldehyde; alpha-hexylcinnamaldehyde; 3 methyl-5-phenylpentanal; 4-methoxybenzaldehyde; 4-hydroxy-3 methoxy-benzaldehyde; 4-hydroxy-3- ethoxybenzaldehyde; 3,4-methylenedioxybenzaldehyde; 3,4- dimethoxybenzaldehyde; 2-methyl-3-(4-methoxyphenyl)propanal; 2-methyl-3-(4- methylenedioxyphenyl)propanal; - aromatic and araliphatic ketones such as e.g. acetophenone; 4- methylacetophenone; 4-methoxyacetophenone; 4-tert-butyl-2,6-dimethylaceto- phenone; 4-phenyl-2-butanone; 4-(4-hydroxyphenyl)-2-butanone; 1-(2- naphthalenyl)-ethanone; 2-benzofuranylethanone; (3-methyl-2- benzofuranyl)ethanone; benzophenone; 1,1,2,3,3,6-hexamethyl-5-indanyl methyl ketone; 6-tert-butyl-1,1 dimethyl-4 indanyl methyl ketone; 1-[2,3-dihydro- 1,1,2,6-tetramethyl-3-(1-methylethyl)-1H-5 indenyl]ethanone; 5^,6^,7^,8^- tetrahydro-3^,5^,5^,6^,8^,8^-hexamethyl-2-acetonaphthone; - aromatic and aliphatic carboxylic acids and esters thereof such as e.g. benzoic acid; phenylacetic acid; methyl benzoate; ethyl benzoate; hexyl benzoate; benzyl benzoate; methyl phenylacetate; ethyl phenylacetate; geranyl phenylacetate; phenylethyl phenylacetate; methyl cinnamate; ethyl cinnamate; benzyl cinnamate; phenylethyl cinnamate; cinnamyl cinnamate; allyl phenoxyacetate; methyl salicylate; isoamyl salicylate; hexyl salicylate; cyclohexyl salicylate; cis-3- hexenyl salicylate; benzyl salicylate; phenylethyl salicylate; methyl 2,4-dihydroxy- 3,6-dimethylbenzoate; ethyl 3-phenylglycidate; ethyl 3-methyl-3-phenylglycidate; - nitrogen-containing aromatic compounds such as e.g.2,4,6-trinitro-1,3-dimethyl- 5 tert-butylbenzene; 3,5-dinitro-2,6-dimethyl-4-tert-butylacetophenone; cinnamonitrile; 3 methyl-5-phenyl-2-pentenonitrile; 3-methyl-5- phenylpentanonitrile; methyl anthranilate; methyl-N-methylanthranilate; Schiff bases of methyl anthranilate with 7 hydroxy-3,7-dimethyloctanal, 2-methyl-3-(4- tert-butylphenyl)propanal or 2,4 dimethyl-3-cyclohexenecarbaldehyde; 6- isopropylquinoline; 6-isobutylquinoline; 6-sec-butylquinoline; 2-(3- phenylpropyl)pyridine; indole; skatole; 2-methoxy-3 isopropyl-pyrazine; 2- isobutyl-3-methoxypyrazine; - phenols, phenyl ethers and phenyl esters such as e.g. estragole; anethole; eugenol; eugenyl methyl ether; isoeugenol; isoeugenyl methyl ether; thymol; carvacrol; diphenyl ether; beta-naphthyl methyl ether; beta-naphthyl ethyl ether; beta-naphthyl isobutyl ether; 1,4-dimethoxybenzene; eugenyl acetate; 2- methoxy-4-methylphenol; 2 ethoxy-5-(1-propenyl)phenol; p-cresyl phenylacetate; - heterocyclic compounds such as e.g.2,5-dimethyl-4-hydroxy-2H-furan-3-one; 2 ethyl-4-hydroxy-5-methyl-2H-furan-3-one; 3-hydroxy-2-methyl-4H-pyran-4-one; 2 ethyl-3-hydroxy-4H-pyran-4-one; - lactones such as e.g. 1,4-octanolide; 3-methyl-1,4-octanolide; 1,4-nonanolide; 1,4-decanolide; 8-decen-1,4-olide; 1,4-undecanolide; 1,4-dodecanolide; 1,5- decanolide; 1,5-dodecanolide; 4-methyl-1,4-decanolide; 1,15-pentadecanolide; cis and trans-11-pentadecen-1,15-olide; cis and trans-12-pentadecen-1,15- olide; 1,16-hexadecanolide; 9-hexadecen-1,16-olide; 10-oxa-1,16- hexadecanolide; 11-oxa-1,16-hexadecanolide; 12-oxa-1,16-hexadecanolide; ethylene 1,12-dodecanedioate; ethylene 1,13-tridecanedioate; coumarin; 2,3- dihydrocoumarin; octahydrocoumarin. The aroma chemical (X) used in the composition are obtained from known commercial sources and procured from Germany. In a preferred embodiment, the composition comprises at least one compound of anyone of the above embodiments 3 to 5 and at least one aroma chemical (X). b) Non-aroma chemical carrier: The non-aroma chemical carrier in the composition of the invention is preferably selected from the group consisting of surfactants, oil components antioxidants, deodorant-active agents and solvents. Preferably the at least one non-aroma chemical carrier is a compound, a mixture of compounds or other additives, which has / have no or no noteworthy sensory properties. The non-aroma chemical carrier can serve for the dilution and / or the fixing of the compounds of anyone of the above embodiments 3 to 5 and – optionally the at least one aroma chemical (X), as defined above, if comprised in the composition. The non-aroma chemical carrier in the composition of the invention is preferably selected from the group consisting of surfactants, oil components, solvents or any mixture of two or more of the aforementioned. c) Solvent In the context of the presently claimed invention, a "solvent" serves for the dilution of the compounds of anyone of the above embodiments 3 to 5 to be used according to the invention without having its own aroma. The amount of solvent(s) is selected depending on the composition. Preferably, the solvent is present in the composition in a total amount of 0.01 wt.% to 99.0 wt.%, more preferably in a total amount of 0.05 wt.% to 95.0 wt.%, yet more preferably in a total amount of 0.1 wt.% to 80.0 wt.%, most preferably 0.1 wt.% to 70.0 wt.%, particularly in a total amount of 0.1 wt.% to 60.0 wt.%, based on the total weight of the composition. In a preferred embodiment, the composition comprises 0.05 wt.% to 10 wt.%, more preferably 0.1 wt.% to 5 wt.%, yet more preferably 0.2 wt.% to 3 wt.% total solvent(s), based on the total weight of the composition. In yet another preferred embodiment of the invention, the composition comprises 20 wt.% to 70 wt.%, more preferably 25 wt.% to 50 wt.% of total solvent(s), based on the total weight of the composition. Preferred solvents are selected from the group consisting of ethanol, isopropanol, diethylene glycol monoethyl ether, glycerol, propylene glycol, 1,2 butylene glycol, dipropylene glycol, triethyl citrate, isopropyl myristate and any mixture of two or more of the aforementioned. In a preferred embodiment, the composition comprises at least one compound of anyone of the above embodiments 3 to 5 and at least one solvent and optionally at least one aroma chemical (X). d) Oil component Preferably, the total oil components are present in an amount of 0.1 to 80 wt.%, more preferably 0.5 to 70 wt.%, yet more preferably 1 to 60 wt.%, even more preferably 1 to 50 wt.%, particularly 1 to 40 wt.%, more particularly 5 to 25 wt.% and specifically 5 to 15 wt.%, based on the total weight of the composition. Preferably the oil components are selected from Guerbet alcohols based on fatty alcohols containing 6 to 18, preferably 8 to 10, carbon atoms and other additional esters, such as myristyl myristate, myristyl palmitate, myristyl stearate, myristyl isostearate, myristyl oleate, myristyl behenate, myristyl erucate, cetyl myristate, cetyl palmitate, cetyl stearate, cetyl isostearate, cetyl oleate, cetyl behenate, cetyl erucate, stearyl myristate, stearyl palmitate, stearyl stearate, stearyl isostearate, stearyl oleate, stearyl behenate, stearyl erucate, isostearyl myristate, isostearyl palmitate, isostearyl stearate, isostearyl isostearate, isostearyl oleate, isostearyl behenate, isostearyl oleate, oleyl myristate, oleyl palmitate, oleyl stearate, oleyl isostearate, oleyl oleate, oleyl behenate, oleyl erucate, behenyl myristate, behenyl palmitate, behenyl stearate, behenyl isostearate, behenyl oleate, behenyl behenate, behenyl erucate, erucyl myristate, erucyl palmitate, erucyl stearate, erucyl isostearate, erucyl oleate, erucyl behenate and erucyl erucate. Also suitable are esters of C18-C38 alkyl-hydroxycarboxylic acids with linear or branched C6- C22 fatty alcohols, more especially dioctyl malate, esters of linear and / or branched fatty acids with polyhydric alcohols (for example propylene glycol, dimer dial or trimer triol), triglycerides based on C6-C10 fatty acids, liquid mono-, di- and triglyceride mixtures based on C6-C18 fatty acids, esters of C6-C22 fatty alcohols and / or Guerbet alcohols with aromatic carboxylic acids, more particularly benzoic acid, esters of dicarboxylic acids with polyols containing 2 to 10 car­ bon atoms and 2 to 6 hydroxyl groups, vegetable oils, branched primary alcohols, substituted cyclohexanes, linear and branched C6-C22 fatty alcohol carbonates such as, for example, dicaprylyl carbonate (Cetiol® CC), Guerbet carbonates based on fatty alcohols containing 6 to 18, preferably 8 to 10, carbon atoms, esters of benzoic acid with linear and / or branched C6-C22 alcohols (for example Finsolv® TN), linear or branched, symmetrical or nonsymmetrical dialkyl ethers containing 6 to 22 carbon atoms per alkyl group such as, for example, dicaprylyl ether (Cetiol® OE), ring opening products of epoxidized fatty acid esters with polyols and hydrocarbons or mixtures thereof. In a preferred embodiment, the composition comprises at least one compound of anyone of the above embodiments 3 to 5, at least one oil component and optionally at least one aroma chemical (X). e) Antioxidants It is to be understood that antioxidants are able to inhibit or prevent the undesired changes in the compositions to be protected caused by oxygen effects and other oxidative processes. The effect of the antioxidants consists in most cases in them acting as free-radical scavengers for the free radicals which arise during autoxidation. In a preferred embodiment, the antioxidant is selected from the group consisting of • amino acids (for example glycine, alanine, arginine, serine, threonine, histidine, tyrosine, tryptophan) and derivatives thereof, • imidazoles (e.g. urocanic acid) and derivatives thereof, • peptides, such as D,L-carnosine, D-carnosine, L-carnosine (=β-Alanyl-L-histidine) and derivatives thereof • carotenoids, carotenes (e.g. alpha-carotene, beta-carotene, lycopene, lutein) or derivatives thereof, • chlorogenic acid and derivatives thereof, • lipoic acid and derivatives thereof (for example dihydrolipoic acid), • auro-thioglucose, propylthiouracil and other thiols (for example thioredoxin, glutathione, cysteine, cystine, cystamine and the glycosyl, N-acetyl, methyl, ethyl, propyl, amyl, butyl and lauryl, palmitoyl, oleyl, gamma-linoleyl, cholesteryl and glyceryl esters thereof) and salts thereof, • dilauryl thiodipropionate, distearyl thiodipropionate, thiodipropionic acid and derivatives thereof (esters, ethers, peptides, lipids, nucleotides, nucleosides and salts), • sulfoximine compounds (for example buthionine sulfoximines, homocysteine sulfoximine, buthionine sulfones, penta-, hexa-, heptathionine sulfoximine), • (metal) chelating agents (e.g. alpha-hydroxy fatty acids, palmitic acid, phytic acid, lactoferrin), • alpha-hydroxy acids (for example citric acid, lactic acid, malic acid), • humic acid, bile acid, bile extracts, bilirubin, biliverdin, boldin (= alkaloid from the plant Peumus boldus, boldo extract, • EDTA, EGTA and derivatives thereof, • unsaturated fatty acids and derivatives thereof (e.g. gamma-linolenic acid, linoleic acid, oleic acid), • folic acid and derivatives thereof, • ubiquinone and ubiquinol and derivatives thereof, • vitamin C and derivatives (for example ascorbyl palmitate, Mg ascorbyl phosphate, ascorbyl acetate), • tocopherols and derivatives (for example vitamin E acetate), • vitamin A and derivatives (for example vitamin A palmitate), • coniferyl benzoate of gum benzoin, rutic acid and derivatives thereof, alpha- glycosylrutin, ferulic acid, furfurylideneglucitol, • butylhydroxytoluene (BHT), butylhydroxyanisole (BHA) • nordihydroguaiacic acid, nordihydroguaiaretic acid, trihydroxybutyrophenone, uric acid and derivatives thereof, mannose and derivatives thereof, • superoxide dismutase, • zinc and derivatives thereof (for example ZnO, ZnSO4), • selenium and derivatives thereof (for example selenomethionine), • stilbenes and derivatives thereof (e.g. stilbene oxide, trans-stilbene oxide) and mixtures of two or more of the aforementioned. In a preferred embodiment, the anti-oxidant is selected from the group consisting of pentaerythrityl, tetra-di-t-butyl-hydroxyhydrocinnamate, nordihydroguaiaretic acid, ferulic acid, resveratrol, propyl gallate, butylhydroxytoluene (BHT), butylhydroxyanisole (BHA), ascorbyl palmitate, tocopherol and mixtures of two or more of the aforementioned. Preferably, the compositions according to the presently claimed invention comprise the anti-oxidant in a total amount of 0.001 to 25 wt.-%, preferably 0.005 to 10 wt.-%, more preferably 0.01 to 8 wt.-%, yet more preferably 0.025 to 7 wt.-%, even more preferably 0.05 to 5 wt.-%, based on the total weight of the composition. In a preferred embodiment, the composition comprises at least one compound of anyone of the above embodiments 3 to 5, at least one antioxidant and optionally at least one aroma chemical (X). f) Deodorant-active agents Deodorizing compositions (deodorants and antiperspirants) counteract, mask or eliminate body odors. Body odors are formed through the action of skin bacteria on apocrine perspiration which results in the formation of unpleasant-smelling degradation products. Preferably the deodorant-active agent is selected from the groups consisting of anti- perspirants, esterase inhibitors, antibacterial agents and mixtures of two or more of the aforementioned. Suitable antiperspirants are selected from the group consisting of salts of aluminum, zirconium or zinc. Examples are aluminum chloride, aluminum chlorohydrate, aluminum dichlorohydrate, aluminum sesquichlorohydrate and complex compounds thereof, for example with 1,2-propylene glycol, aluminum hydroxyallantoinate, aluminum chloride tartrate, aluminum zirconium trichlorohydrate, aluminum zirconium tetrachlorohydrate, aluminum zirconium pentachlorohydrate and complex compounds thereof, for example with amino acids, such as glycine. Aluminum chlorohydrate, aluminum zirconium tetrachlorohydrate, aluminum zirconium pentachlorohydrate and complex compounds thereof are preferably used. Preferably, the anti-perspirant is selected from the group consisting of aluminum chloride, aluminum chlorohydrate, aluminum dichlorohydrate, aluminum sesquichlorohydrate, aluminum hydroxyallantoinate, aluminum chloride tartrate, aluminum zirconium trichlorohydrate, aluminum zirconium tetrachlorohydrate aluminum zirconium pentachlorohydrate and mixtures of two or more of the aforementioned. Where perspiration is present in the underarm region, extracellular enzymes-esterases, mainly proteases and / or lipases are formed by bacteria and split the esters present in the perspiration, releasing odors in the process. Suitable esterase inhibitors are for example trialkyl citrates, such as trimethyl citrate, tripropyl citrate, triisopropyl citrate, tributyl citrate and, in particular, triethyl citrate. Esterase inhibitors inhibit enzyme activity and thus reduce odor formation. The free acid is probably released by the cleavage of the citric acid ester and reduces the pH value of the skin to such an extent that the enzymes are inactivated by acylation. Other esterase inhibitors are sterol sulfates or phosphates such as, for example, lanosterol, cholesterol, campesterol, stigmasterol and sitosterol sulfate or phosphate, dicarboxylic acids and esters thereof, for example glutaric acid, glutaric acid monoethyl ester, glutaric acid diethyl ester, adipic acid, adipic acid monoethyl ester, adipic acid diethyl ester, malonic acid and malonic acid diethyl ester, hydroxycarboxylic acids and esters thereof, for example citric acid, malic acid, tartaric acid or tartaric acid diethyl ester, zinc glycinate and mixtures of two or more of the aforementioned. Preferably, the esterase inhibitor is selected from the group consisting of trimethyl citrate, tripropyl citrate, triisopropyl citrate, tributyl citrate triethyl citrate, lanosterol, cholesterol, campesterol, stigmasterol, sitosterol sulfate, sitosterol phosphate, glutaric acid, glutaric acid monoethyl ester, glutaric acid diethyl ester, adipic acid, adipic acid monoethyl ester, adipic acid diethyl ester, malonic acid, malonic acid diethyl ester, citric acid, malic acid, tartaric acid, tartaric acid diethyl ester zinc glycinate and mixtures of two or more of the aforementioned. Preferably, the compositions according to the presently claimed invention comprise the esterase inhibitor in a total amount in the range of 0.01 to 20 wt.-%, preferably 0.1 to 10 wt.-% and more particularly 0.5 to 5 wt.-%, based on the total weight of the composition. The term “anti-bacterial agents” as used herein encompasses substances which have bactericidal and / or bacteriostatic properties. Typically these substances act against gram-positive bacteria such as, for example, 4-hydroxybenzoic acid and salts and esters thereof, N-(4-chlorophenyl)-N'-(3,4-dichlorophenyl)-urea, 2,4,4'-trichloro-2'- hydroxydiphenylether (triclosan), 4-chloro-3,5-dimethylphenol, 2,2'-methylene-bis-(6- bromo-4-chlorophenol), 3-methyl-4-(1-methylethyl)-phenol, 2-benzyl-4-chlorophenol, 3- (4-chlorophenoxy)-propane-1,2-diol, 3-iodo-2-propinyl butyl carbamate, chlorhexidine, 3,4,4'-trichlorocarbanilide (TTC), phenoxyethanol, glycerol monocaprate, glycerol monocaprylate, glycerol monolaurate (GML), diglycerol monocaprate (DMC), salicylic acid-N-alkylamides such as, for example, salicylic acid-n-octyl amide or salicylic acid-n- decyl amide. Preferably, the antibacterial agent is selected from the group consisting of chitosan, phenoxyethanol, 5-chloro-2-(2,4-dichlorophenoxy)-phenol, 4-hydroxybenzoic acid and salts and esters thereof, N-(4-chlorophenyl)-N'-(3,4-dichlorophenyl)-urea, 2,4,4'- trichloro-2'-hydroxydiphenylether (triclosan), 4-chloro-3,5-dimethylphenol, 2,2'- methylene-bis-(6-bromo-4-chlorophenol), 3-methyl-4-(1-methylethyl)-phenol, 2-benzyl- 4-chlorophenol, 3-(4-chlorophenoxy)-propane-1,2-diol, 3-iodo-2-propinyl butyl carbamate, chlorhexidine, 3,4,4'-trichlorocarbanilide (TTC), phenoxyethanol, glycerol monocaprate, glycerol monocaprylate, glycerol monolaurate (GML), diglycerol monocaprate (DMC), salicylic acid-N-alkylamides and mixtures of two or more of the aforementioned. Preferably, the composition according to the presently claimed invention comprises the antibacterial agent(s) in a total amount in the range of 0.01 to 5 wt.% and preferably 0.1 to 2 wt.-%, based on the total weight of the composition. In a preferred embodiment, the composition comprises at least one compound of anyone of the above embodiments 3 to 5, at least one deodorant active agent and optionally at least one aroma chemical (X). g) Surfactants Preferably, the surfactant is selected from the group consisting of anionic, non­ionic, cationic, amphoteric, zwitterionic surfactant and a mixture of two or more of the aforementioned. More preferably, the surfactant is an anionic surfactant. Preferably, the compositions according to the invention contain the surfactant(s), in a total amount of 0 to 40 wt.%, more preferably 0 to 20 wt.%, more preferably 0.1 to 15 wt.%, and particularly 0.1 to 10 wt.%, based on the total weight of the composition. Preferable nonionic surfactants are fatty alcohol polyglycol ethers, alkylphenol polyglycol ethers, fatty acid polyglycol esters, fatty acid amide polyglycol ethers, fatty amine polyglycol ethers, alkoxylated triglycerides, mixed ethers and mixed formals, optionally partly oxidized alk(en)yl oligoglycosides or glucuronic acid derivatives, fatty acid-N-alkyl glucamides, protein hydrolysates (particularly wheat-based vegetable products), polyol fatty acid esters, sugar esters, sorbitan esters, polysorbates and amine oxides. If the nonionic surfactants contain polyglycol ether chains, they may have a conventional homolog distribution, although they preferably have a narrow-range homolog distribution. Zwitterionic surfactants are surface-active compounds which contain at least one quaternary ammonium group and at least one COO(-) or SO3(-) group in the molecule. Particularly suitable zwitterionic surfactants are the so-called betaines, such as the N- alkyl-N,N-dimethyl ammonium glycinates, for example, cocoalkyl dimethyl ammonium glycinate, N-acylaminopropyl-N,N-dimethyI ammonium glycinates, for example, cocoacylaminopropyl dimethyl ammonium glycinate, and 2-alkyl-3-carboxymethyl-3- hydroxyethyl imidazolines, containing 8 to 18 carbon atoms in the alkyl or acyl group, and cocoacylaminoethyl hydroxyethyl carboxymethyl glycinate. The fatty acid amide derivative known under the CTFA name of Cocamidopropyl Betaine is particularly preferred. Ampholytic surfactants are also suitable, particularly as co-surfactants. Ampholytic surfactants are surface-active compounds which, in addition to a C8 -C18 alkyl or acyl group, contain at least one free amino group and at least one -COOH or -SO3H group in the molecule and which are capable of forming inner salts. Examples of suitable ampholytic surfactants are N-alkyl glycines, N-alkyl propionic acids, N-alkylaminobutyric acids, N-alkyliminodipropionic acids, N-hydroxyethyl-N-alkylamidopropyl glycines, N- alkyl taurines, N-alkyl sarcosines, 2-alkylaminopropionic acids and alkylaminoacetic acids containing around 8 to 18 carbon atoms in the alkyl group. Particularly preferred ampholytic surfactants are N-cocoalk-ylaminopropionate, cocoacylaminoethyl aminopropionate and acyl sarcosine. Anionic surfactants are characterized by a water­solubilizing anionic group such as, for example, a carboxylate, sulfate, sulfonate or phosphate group and a lipophilic group. Dermatologically safe anionic surfactants are known to the practitioner in large numbers from relevant textbooks and are commercially available. They are, in particular, alkyl sulfates in the form of their alkali metal, ammonium or alkanolammonium salts, alkylether sulfates, alkylether carboxylates, acyl isethionates, acyl sarcosinates, acyl taurines containing linear C12-C18 alkyl or acyl groups and sulfosuccinates and acyl glutamates in the form of their alkali metal or ammonium salts. Particularly suitable cationic surfactants are quaternary ammonium compounds, preferably ammonium halides, more especially chlorides and bromides, such as alkyl trimethyl ammonium chlorides, dialkyl dimethyl ammonium chlorides and trialkyl methyl ammonium chlorides, for example, cetyl trimethyl ammonium chloride, stearyl trim ethyl ammonium chloride, distearyl dimethyl ammonium chloride, lauryl dimethyl ammonium chloride, lauryl dimethyl benzyl ammonium chloride and tricetyl methyl ammonium chloride. In addition, the readily biodegradable quaternary ester compounds, such as, for example, the dialkyl ammonium methosulfates and methyl hydroxyalkyl dialkoyloxyalkyl ammonium methosulfates marketed under the name of Stepantexe and the corresponding products of the Dehyquart® series, may be used as cationic surfactants. “Esterquats” are generally understood to be quaternized fatty acid triethanolamine ester salts. They can provide the compositions with particular softness. They are known substances which are prepared by the relevant methods of organic chemistry. Other cationic surfactants suitable for use in accordance with the invention are the quaternized protein hydrolysates. Due to the characteristic sensory property of the compound of formula (I) and its substantivity, tenacity as well as stability, it can especially be used to provide an odor, preferably a fragrance impression to surfactant-containing compositions such as, for example, cleaners (in particular laundry care products and all-purpose cleaners). It can preferably be used to impart a long-lasting rose note, rhubarb note, grapefruit note, sweet note, powdery note, sandalwood note to a surfactant comprising composition. In a preferred embodiment, the composition comprises at least one compound of anyone of the above embodiments 3 to 5 and at least one surfactant and optionally at least one aroma chemical (X). Suitable compositions are for example perfume compositions, body care compositions (including cosmetic compositions and products for oral and dental hygiene), hygiene articles, cleaning compositions (including dishwashing compositions), textile detergent compositions, compositions for scent dispensers, foods, food supplements, pharmaceutical compositions and crop protection compositions. Perfume compositions can be selected from fine fragrances, air fresheners in liquid form, gel-like form or a form applied to a solid carrier, aerosol sprays, scented cleaners, perfume candles and oils, such as lamp oils or oils for massage. Examples for fine fragrances are perfume extracts, Eau de Parfums, Eau de Toilettes, Eau de Colognes, Eau de Solide and Extrait Parfum. Body care compositions include cosmetic compositions and products for oral and dental hygiene, and can be selected from after-shaves, pre-shave products, splash colognes, solid and liquid soaps, shower gels, shampoos, shaving soaps, shaving foams, bath oils, cosmetic emulsions of the oil-in-water type, of the water-in-oil type and of the water-in- oil-in-water type, such as e.g. skin creams and lotions, face creams and lotions, sunscreen creams and lotions, after-sun creams and lotions, hand creams and lotions, foot creams and lotions, hair removal creams and lotions, after-shave creams and lotions, tanning creams and lotions, hair care products such as e.g. hairsprays, hair gels, setting hair lotions, hair conditioners, hair shampoo, permanent and semi-permanent hair colorants, hair shaping compositions such as cold waves and hair smoothing compositions, hair tonics, hair creams and hair lotions, deodorants and antiperspirants such as e.g. underarm sprays, roll-ons, deodorant sticks and deodorant creams, products of decorative cosmetics such as e.g. eye-liners, eye-shadows, nail varnishes, make-ups, lipsticks and mascara, and products for oral and dental hygiene, such as toothpaste, dental floss, mouth wash, breath fresheners, dental foam, dental gels and dental strips. Hygiene articles can be selected from joss sticks, insecticides, repellents, propellants, rust removers, perfumed freshening wipes, armpit pads, baby diapers, sanitary towels, toilet paper, cosmetic wipes, pocket tissues, dishwasher and deodorizer. Cleaning compositions, such as e.g. cleaners for solid surfaces, can be selected from perfumed acidic, alkaline and neutral cleaners, such as e.g. floor cleaners, window cleaners, dishwashing compositions both for handwashing and machine washing use, bath and sanitary cleaners, scouring milk, solid and liquid toilet cleaners, powder and foam carpet cleaners, waxes and polishes such as furniture polishes, floor waxes, shoe creams, disinfectants, surface disinfectants and sanitary cleaners, brake cleaners, pipe cleaners, limescale removers, grill and oven cleaners, algae and moss removers, mold removers, facade cleaners. Textile detergent compositions can be selected from liquid detergents, powder detergents, laundry pre-treatments such as bleaches, soaking agents and stain removers, fabric softeners, washing soaps, washing tablets. Food means a raw, cooked, or processed edible substance, ice, beverage or ingredient used or intended for use in whole or in part for human consumption, or chewing gum, gummies, jellies, and confectionaries. A food supplement is a product intended for ingestion that contains a dietary ingredient intended to add further nutritional value to the diet. A dietary ingredient may be one, or any combination, of the following substances: a vitamin, a mineral, an herb or other botanical, an amino acid, a dietary substance for use by people to supplement the diet by increasing the total dietary intake, a concentrate, metabolite, constituent, or extract. Food supplements may be found in many forms such as tablets, capsules, soft gels, gel caps, liquids, or powders. Pharmaceutical compositions comprise compositions which are intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease as well as articles (other than food) intended to affect the structure or any function of the body of man or other animals. Crop protection compositions comprise compositions which are intended for the managing of plant diseases, weeds and other pests (both vertebrate and invertebrate) that damage agricultural crops and forestry. Preferably, the compositions according to the invention further comprises at least one auxiliary agent selected from the group consisting of preservatives, abrasives, anti-acne agents, agents to combat skin aging, anti-cellulite agents, antidandruff agents, anti- inflammatory agents, irritation-preventing agents, irritation-alleviating agents, astringents, sweat-inhibiting agents, antiseptics, anti-statics, binders, buffers, carrier materials, chelating agents, cell stimulants, care agents, hair removal agents, emulsifiers, enzymes, essential oils, fibres, film formers, fixatives, foam formers, foam stabilizers, substances for preventing foaming, foam boosters, fungicides, gelling agents, gel-forming agents, hair care agents, hair shaping agents, hair smoothing agents, moisture-donating agents, moisturizing substances, humectant substances, bleaching agents, strengthening agents, stain removal agents, optical brighteners, impregnating agents, soil repellents, friction-reducing agents, lubricants, moisturizing creams, ointments, opacifiers, plasticizers, covering agents, polish, shine agents, polymers, powders, proteins, refatting agents, exfoliating agents, silicones, skin-calming agents, skin-cleansing agents, skin care agents, skin-healing agents, skin lightening agents, skin-protective agents, skin-softening agents, cooling agents, skin-cooling agents, warming agents, skin-warming agents, stabilizers, UV-absorbent agents, UV filters, fabric softeners, suspending agents, skin-tanning agents, thickeners, vitamins, waxes, fats, phospholipids, saturated fatty acids, mono or polyunsaturated fatty acids, alpha hydroxy acids, polyhydroxy fatty acids, liquefiers, dyes, color-protection agents, pigments, anti-corrosives, polyols, electrolytes and silicone derivatives. h) Preparation of compositions and methods to impart an aroma impression to a composition. One embodiment of the invention is directed to a method of preparing a composition of compound of anyone of the above embodiments 3 to 5 comprising: (i) at least one aroma compound (X) other than compounds according to the present invention or (ii) at least one non-aroma chemical carrier, or both of (i) and (ii). The invention is also directed to a method for boosting the aroma impression of a composition, wherein the method comprises incorporating at least one compound of anyone of the above embodiments 3 to 5 into a composition. In particular, the invention is directed to a method of preparing a perfume composition, body care composition, hygiene article, cleaning composition, textile detergent composition, composition for scent dispensers, food, food supplement, pharmaceutical composition or crop protection composition, comprising including at least one compound of anyone of the above embodiments 3 to 5 in a perfume composition, body care composition, hygiene article, cleaning composition, textile detergent composition, composition for scent dispensers, food, food supplement, pharmaceutical composition or crop protection composition. In one embodiment the invention is directed to a method for imparting a note reminiscent of balsamic note, camphoraceous note, beeswax like note, floral note, citrus note, watery note, gourmand note, fresh note, herbal note natural note or combination of two or more note elements to a perfume composition, body care composition, hygiene article, cleaning composition, textile detergent composition, composition for scent dispensers, food, food supplement, pharmaceutical composition or crop protection composition, which comprises including at least one compound of anyone of the above embodiments 3 to 5 in a perfume composition, body care composition, hygiene article, cleaning composition, textile detergent composition, composition for scent dispensers, food, food supplement, pharmaceutical composition or crop protection composition. i) Amounts Generally, the total amount of compounds of formula (I) in the compositions, methods and uses according to the present invention is typically adapted to the particular intended use or the intended application and can, thus, vary over a wide range. As a rule, the customary standard commercial amounts for aroma chemicals, preferably for scents are used. Preferably the compositions according to the invention comprise compounds of anyone of the above embodiments 3 to 5 in a total amount of 0.001 to 99.9 wt.%, based on the total weight of the composition. Particularly, the compositions comprise compounds of anyone of the above embodiments 3 to 5 in a total amount of 0.001 to 99.5 wt.%, preferably of 50 to 99 wt.%, more preferably of 80 to 95 wt.% and in particular of 90 to 95 wt.%, based on the total weight of the composition. More particularly, the compositions comprise compounds of anyone of the above embodiments 3 to 5 in a total amount of 0.005 to 80 wt.%, preferably of 0.1 to 30 wt.%, more preferably of 1 to 20 wt.%, and in particular of 5 to 15 wt.%, based on the total weight of the composition. Even more particularly, the compositions comprise the compounds of anyone of the above embodiments 3 to 5 in a total amount of 0.001 to 20 wt.%, preferably of 0.005 to 6 wt.%, more preferably of 0.05 to 4 wt.%, and in particular of 0.1 to 3 wt.%, based on the total weight of the composition. EXPERIMENTAL PART 1. Reagents and buffers Commercially available reagents and solvents were purchased and used without further purification. The substrates were obtained from the following sources: 4a: Sodium 2-oxobutyrate >98,0% TCI Deutschland GmbH 5a: 3-Methyl-2-oxopentanoic acid ≥98% Sigma-Aldrich 4b: Propionaldehyd 97% Sigma-Aldrich 5b: 2-Methylbutyraldehyde ≥95%, FG Sigma-Aldrich 2. DNAs and cloning 2.1 Sequences Gst-TK libraries were obtained from W.D. Fessner, TU Darmstadt. Enzyme used for the enzymatic carboligation of different acids and aldehydes using transketolase as catalyst were recombinantly produced in Escherichia coli. The coding sequence for the TKgst [9,10] cloned after a His-tag in pGEN768, along with the previous other variants, was obtained from Prof. Hecquet (University of Clermont Auvergne, UCA). The gene is under control of the T7 promotor, leading to its overexpression. TKgst was chosen as potential catalyst for filbertone due to its thermostability and well characterisation. In analogy TKecowas cloned into pGSJ427 as described by P. Asztalos, C. Parthier, R. Golbik, M. Kleinschmidt, G. Hübner, M. S. Weiss, R. Friedemann, G. Wille, K. Tittmann, Biochemistry 2007, 46, 12037–12052. 2.2 Library screening Selection of potential enzyme candidates for these experiments was done based on a pre-screen of 384 variants using 5a and 4b or 4a and 5b substrates and a medium throughput pH assay

[0011] . Top screening mutants from these efforts were analysed by LC-MS / MS and GC-MS, investigating potential acyloin formation. 2.3 Preparation of biocatalyst In order to prepare the biocatalyst, the plasmid was transformed via heat-shock

[0013] to E. coli BL21(DE3)Gold competent cells (Agilent Technologies) and incubated at 37 ºC overnight (ON).Transformants were used to inoculate a 3 mL pre-culture (LB medium with 50 µg·mL-1kanamycin) which was grown overnight at 37ºC. The preculture was used to inoculate 50 mL LB main culture containing 50 µg·mL-1kanamycin. Isopropyl β- D-1-thiogalactopyranoside (IPTG) at 0.1 mM was introduced when the OD range was 0.7-0.8 to induce TKgst gene expression. The cells were grown overnight (20 h) at 30 ºC, 180 rpm, 25 mm deflection, and harvested by centrifugation 11,850 rcf for 10‘. The pellets from the same mutants were collected in the same Falcon tube and resuspended with 45 mL of triethanolamine (TEA) buffer 2 mM pH 7.5. The cell pellets resuspended in TEA buffer were transferred to a 100 mL round bottom flask. Lysis with lysozyme (10,000 U / mL) and benzonase (4 U / mL), preceded the heat-shock purification[9]. Afterwards, the crude extract was transferred to a Falcon tube, centrifuged at 10,015 rcf for 30 min RT, and the supernatant was lyophilized for 48 h. 2.3.1 Protein analysis Protein concentration was determined by Bradford assay

[0014] . Different samples (plus controls) were taken during the biocatalyst preparation and analysed in SDS-PAGE

[0015] (NuPAGETM 4-12% Bis-Tris Gel 1,5 mm x 10 well from Invitrogen) using Serva Blue R for staining. 3. Biocatalytic conversions 3.1 Reaction mixtures and process conditions 3.1.1 Reaction mixture 1 The preparative scale volumes and concentrations are reported below (adapted from

[0016] ): A 2 mL reaction (all the solutions are prepared in TEA 2 mM pH 7.5): Constituent Final concentration V from stock MgCl29.4 mM TPP 2.4 mM 1 mL TK variant 0.5 mg / mL Donor Substrates 4a, 5a 50 mM 500 µL Acceptor Substrates 4b, 5b 50 mM 500 µL 4a = αKB; 5a = MOPA; 4b = Propanal; 5b = 2-Methylbutanal The cofactors, MgCl2 and TPP, were mixed to a final volume of 1 mL TEA buffer 2 mM pH 7.5 and the pH was adjusted to about 7. Preincubation was done (50ºC, 750 rpm, 30 min) and afterwards the substrates (500 mM, pH ~7) were added to a final volume of 2 mL TEA buffer 2 mM pH 7.5. After 18h the reaction was stopped by centrifugation (18,213 rcf, 10 min, 4 ºC) and acetonitrile addition. Since temperature optimum of transketolase was at 50ºC

[0016] , reactions were carried out at this temperature. The tested substrates have been: 5a (as donor) with 4b (as acceptor), and 4a (as donor) with 5b(as acceptor). Reaction mixtures were analysed by LC-MS / MS and GC-MS. 3.1.2 Reaction mixture 2 This mixture is used to examine reactivity between two different acceptor molecules as enzyme substrates: All the solutions are prepared in TEA 2 mM pH 7.5: Constituent Final concentration MgCl29.4 mM TPP 2.4 mM TK variant 2 mg / mL Acceptor Substrate 4b 25 mM Acceptor Substrate 5b 100 or 200 mM 4b = Propanal; 5b= 2-Metylbutanal The reaction was carried out as described above for reaction mixture 1. 3.1.3 Reaction mixtures 3 These mixtures were used in experiments investigating an increase of yield of 3- hydroxy-5-methyl-heptan-4-one (6). All the solutions are prepared in TEA 2 mM pH 7.5: Constituent Final concentration MgCl2 9.4 mM TPP 2.4 mM TK variant 0.5 mg / mL? Donor Substrate 5a 10 to 100 mM Acceptor Substrate 4b 100 or 200 mM 4b = Propanal; 5a = MOPA The reaction was carried out as described above for reaction mixture 1. 3.1.4 Reaction mixtures 4 These reaction mixtures were used in an experiment to investigate carboligation of two different donor acids αKB (4a) and MOPA (5a). All the solutions are prepared in TEA 2 mM pH 7.5: Constituent Final concentration MgCl29.4 mM TPP 2.4 mM TK variant gstTK47 3 mg / mL Donor Substrates 4a 25 mM Donor Substrates 5a 100mM or 200 mM 4a = αKB; 5a = MOPA; The reaction was carried out as described above for reaction mixture 1. 3.2 Analytics 3.2.1 HPLC-MS Achiral Method Device: Thermo Fisher "Vanquish" with MS-Detector "ISQEC" Chromatographic conditions Separation column: Phenomenex Kinetex C18, 100x2.1mm Eluent: Eluent A: 0.1% formic acid in H2O Eluent B: 0.1% formic acid in acetonitrile The elution gradient is reported below: Time Eluent Eluent B (min) A 0 100% 0% 1 100% 0% 5 50% 50% 6 0% 100% 7 0% 100% 7.5 100% 0% 10 100% 0% Flow: 0.5 mL / min Temperature: 40 ºC Injection volume: 1 µL or 10 µL Detector: 212 nm (UV) MS Settings MS Detection: SIM 101.10 neg SIM 117.20 pos. SIM 127.20 pos SIM 129.15 neg SIM 145.20 pos SIM 173.25 pos Full Scan 60-600 pos Full Scan 60-600 neg Source CID Voltage: 30V 3.2.2 HPLC-MS / MS Device: Thermo Vanquish Flex UHPLC system Chromatographic conditions Separation column: Acquity BEH C18, 510 x 2.1 mm, 1.7 µm column (Waters, Germany) Eluent: Eluent A: 0.1% formic acid in H2O Eluent B: 0.1% formic acid in acetonitrile The elution gradient is reported below: Time Eluent Eluent (min) A B 0 85% 15% 0.5 85% 15% 6.5 25% 75% 7 5% 95% 9 5% 95% 9.1 85% 15% 13.5 85% 15% Flow: 400 µL / min Oven temperature: 45 ºC Injection volume: 5 µL Detector: 190 to 680 nm (DAD) MS Settings Scan 50 m / z Begin: Scan End: 1550 m / z Ion Positive polarity: Scan Mode MS Spectrum Settings Rate Mode: Spectra Rate Rate Value: 20.00 Hz MS 1 x Averaging: Source Source Type: ESI End Plate 500 V 1 nA Offset: Capillary: 4500 V 0 nA Nebulizer: 1.5 Bar 0.5 Bar Dry gas: 2.5 L / min 2.5 L / min Dry Temp 200 ºC 201 ºC Transfer Deflection 1 70.0 V Delta: Funnel 1 RF: 200.0 Vpp isCID Energy: 0.0 eV Funnel 2 RF: 200.0 Vpp Multipole RF: 200.0 Vpp Collision Cell Collision 7.0 eV Energy: Collision RF: 1250.0 Vpp Quadrupole Ion Energy: 3.0 eV Low Mass: 70.00 m / z Focus Pre TOF Transfer Time: 80.0 µs Pre Pulse Storage: 5.0 µs Detection High Sensitivity Detection – Low x Sample Amount Focus Mode: √ Sweeping Collision RF Collision Energy Time [%] Transfer Time [µs] [Vpp] [%] 1 0 200.0 20.0 100.0 2 25 200.0 20.0 250.0 3 50 1250.0 80.0 250.0 4 75 1250.0 80.0 100.0 3.2.3 GC Device: Agilent 7890B Gas chromatograph with SSL-Injector and FID detector Chromatographic conditions Separation column: TG-WAX MS 30m x 0.25mm x 0.25µm Carrier gas: Hydrogen Carrier liquid 0,6mL / min; const. Flow Injector temperature: 280°C Split: 1:10 Injection volume: 1µL Detector: FID Detector temperature: 320 °C The oven program is reported below: Heating Holding Temperature rate time [ºC] [ºC / min] [min] Initial 40 2 Ramp A 10 240 10 Run time: 32.0 min 3.2.4 GC-MS Device: Agilent 7890B Gas chromatograph with SSL-Injector and FID detector Chromatographic conditions Separation column: StabilWax 30m x 0.32 mm x 0.5µm Carrier gas: Helium Carrier liquid: 1.6mL / min; const. Flow Split: 1:10 in case of split mode Injection volume: 1µL Detector: FID or EI Oven program: Heating Holding Temperature rate time [ºC] [ºC / min] [min] Initial 40 2 Ramp A 10 230 20 Run time: 41.0 min MS FI Conditions splitless Ionization Mode FI+ Tune Counter Electrode [V] -10000 Acquisition m / z [25.00] [800.00] MS EI conditions Scan Parameters Low Mass: 25 High Mass: 785 MS Zones MS Source: 300 ºC maximum 350 ºC MS Quad: 150 ºC maximum 200 ºC Timed Events Trace Ion Detection is OFF. Emission: 34.593 Energy: 70.007 4. Results and Discussion 4.1 Biocatalysts Thiamine diphosphate (TPP) is the water-soluble vitamin B1 which is an essential coenzyme in all living beings. The negatively charged C2 atom from the thiazolium ring attacks the carbonyl carbon of the substrate

[0017] . This inversion of polarity (“umpolung“) is the unique feature of this reaction. The carbanion configuration that is in resonance with the enamine formed after the binding of the donor to the mentioned carbon (Figure 3) is crucial for the C-C-bond formation. The carbanion attacks the carbonyl of the acceptor aldehyde creating the new bond. Proton abstraction and electron shuffling back to the positively charged nitrogen atom results in liberation of the acyloin product and regeneration of the TPP-cofactor. The transketolase that has been tested is obtained from Geobacillus stearothermophilus (TKgst), a thermophilic organism, with a temperature optimal of 50ºC[9]. Its thermostability facilitates the up- and downstream processing, provides better resistance against conditions that can destabilize proteins, along with implying a correlation with mutational robustness and organic cosolvent stability[9,18]. Moreover, its tk gene is orthologous to Bacillus anthracis tk1 gene whose structure has high homology with the mainly Transketolase genes for biocatalysis[9]. All these reasons in addition to the high sequence similarity between the TKgst to well characterised transketolases[9,16,19], generate a great interest in the choice of this thermostable enzyme. In a first medium throughput screening TKgst libraries have been screened with the pH assay

[0011] . In total 27 hits were obtained: 18 of them apparently converting 5a, 4b and 9 active on 4a and 5b. Variants of TKgst with most prominent activity on filbertone precursors in the pH-assay were sequenced. In parallel the following mutations were found as interesting hot-spots

[0021] : • mutation at L118 since it is one of the 3 aa that have structurally equivalent positions when superposing TKecoand Pyruvate decarboxylase (PDC) in addition to • mutation at H28 since this position is close (below 2 Å) to I477 in PDC; a conserved residue among PDCs from different organisms with an important role in substrate recognition and enantioselectivity. H68, H263 are also aa nearby I477. Further mutations; H102L,L118I and H474S

[0012] , in mTKgst lead to the mutant used in the current work. Variants for detailed investigation were chosen by pH assay performance and state of the art in literature: H28T, H68G, H102Y / H474N, H102L / 118I

[0012] , H102L / L118I / H474S

[0012] , L382N / D470T

[0016] . 4.2 Production of transketolase Wild type TK[9], along with a variant that codes for a stop-codon in the middle of the sequence as negative control, was expressed in E. coli BL21(DE3) Gold strain and purified by heat-shock[9](Figure 4). 4.3 Preliminary characterisation and product identification The pH-assay used in the initial screening at the TU Darmstadt indicates enzymatic activity only by detection of the CO2 release. In order to get more insight additional analytical tools were used to characterize the enzyme reaction. 4.3.1 Identification of reaction products: 3-hydroxy-5-methyl-heptan-4-one and 4-Hydroxy-5-methyl-3-heptanone This experiment was performed with different variants of the biocatalyst (Table 2), leading to the C-C bond formation due to condensation of an aldehyde and an α-keto acid. As expected carboligation of α-keto acid and aldehyde would be detected. In addition to this it was also observed that TKgst is capable of forming homocoupling of 4b as well as of 5b resulting in the respective 8 and 10 acyloins, respectively. A similar homocoupling of aldehyde moieties has been observed with the related TPP dependent pyruvate decarboxylase

[0022] .

[0002] Table 2: Overview of different analytical methods for the detection of different transketolase products Donor 5a 4a 5a 4a Substrates Acceptor 4b 4b 5b 5b Structure Products 6 7 10 8 Name 3-hydroxy-5-methyl- 4-Hydroxy-5- 5-Hydroxy-3,6- 4-Hydroxy-3- heptan-4-one methyl-3-heptanone dimethyl-4-octanone hexanone Analytical LC-MS √ √ √ √ techniques with which LC- MS / MS n.t. √ n.t. √ the compound GC √ √ n.d. √ was detected GC-MS √ √ n.d. √ n.d: non-detected. n.t.: non-tested

[0003] Table 3: Sum-up table of all the different compounds detected using different analytical methods. For HPLC-MS (cf.3.2.1), HPLC-MS / MS (cf.3.2.2), GC (cf.3.2.3), GC-MS (cf. 3.2.4). Donor 5a 4a 5a 4a Substrates Acceptor 4b 4b 5b 5b Structure Products 6 7 10 8 3-hydroxy-5- 4-Hydroxy-5- 5-Hydroxy-3,6- Name methyl-heptan-4- methyl-3- dimethyl-4- 4-Hydroxy-3- one heptanone octanonehexanoneAnalyticalmethod WT + + n.t. n.t. LC-MS H28T + + n.d. - GC H68G + + n.d. - GC H102L / L118I + + n.d. - GC H102L LC-MS / L118I + + n.d. + GC / H474S GC-MS TKgst H102M + - n.d. - GC variants used for H102L / H47 + + n.d. + GC the 4N preparative L118F / H474N + + n.d. + GC synthesis of H102V filbertone / L118F + + n.d. - GC precursor / H474D – product H102Y analysis / H474N + - n.d. - GC via GC L382N / D470S + + n.t. n.t. LC-MS L382D / D470S + + n.t. n.t. LC-MS LC-MS L382N + + n.d. LC- / D470T + MS / MS GC L382E / D470T + + n.t. n.t. LC-MS D470S + + n.t. n.t. LC-MS Donor 5a 4a 5a 4a Substrates Acceptor 4b 4b 5b 5b Structure Products 6 7 10 8 3-hydroxy-5- 4-Hydroxy-5- 5-Hydroxy-3,6- Name methyl-heptan-4- methyl-3- dimethyl-4- 4-Hydroxy-3- one heptanone octanonehexanoneAnalyticalmethod D470T + + n.t. n.t. LC-MS WT - - n.d. - GC TKeco H26T - - n.d. - GC variants H66A - - n.d. - GC used for the H66G - - n.d. - GC preparative synthesis H100L + - n.d. - GC of filbertone H100L recursor / + + n.d. + GC p L116 H100L / L116 - - n.d. - GC / H473S n.d: non-detected. n.t.: non-tested So far, all the obtained data are qualitative (GCs) or semiquantitative at most 5 (LC-MS), however some semi-quantitative estimations have been assessed. From the LC-MS results, the mutants tested at that moment, were compared based on the area under the curve and the best one was chosen for further LC-MS / MS analysis. Once more mutants were obtained, these were also analysed by LC-MS. Since variant L382N / D470T of those gave even higher area under the curve, this variant was chosen0 for finding a more suitable detection method. Initial attempts to analyse products by TLC or NMR were not successful, however GC runs with a wax column does show the product peaks (corroborated via GC-MS 3.2.4). Therefore, this method, up to now, has been established as the main screening technique. When comparing the GC peak height, it can be seen that the main product is the C6-acyloin 4-hydroxyhexan-3-one (8), coming from the homocoupling of propanal (4b), followed by the C7-acyloin 3-hydroxy-5-methyl-heptan-4-one (6), and – to a lesser extent - the C7-acyloin 7 (4-hydroxy-5-methylheptan-3-one). Also it is worth mentioning that not all enzyme variants perform homocoupling of 4b. Summary Screening of TKgst libraries identified several transketolase variants, that show enzymatic activity on α-ketobutyric acid and 2-methylbutanal as well as 3-methyl-2- oxopentanoic acid and 2-methylbutanal. Besides cross-coupled products 3-hydroxy-5- methyl-heptan-4-one (6) and 4-hydroxy-5-methyl-3-heptanone (7) also homocoupling leading to 5-hydroxy-3,6-dimethyl-4-octanone and 4-hydroxy-3-hexanone, respectively has been observed. Elimination of water from (6) would finally yield the target molecule filbertone (1). The reaction products were be identified by mass spectroscopy. 4.4 Investigating the influence of different MOPA / Propanal concentrations on the yield of 3-hydroxy-5-methyl-heptan-4-one (6) Reaction media were prepared as described above in section 3.1.3 containing MOPA and propanal in different proportions. The carboligation reaction was catalysed by the triple mutant gstTK47. Composition of the obtained reaction mixture was analysed by GC. The results are shown in the Table 4 below. Table 4 RT (min) Area (pA*min) 867 Homocoupling 1stpeak 2ndpeak 1stpeak 2ndpeak 12.7 stg super 1 50 mM MOPA small in the -E 50 mM Propanal - others nothing - - - at 12.73 100 mM MOPA 12’ 12.73’ 12.96’ 13.14’ 13.63’ 2 100 mM Propanal 0.679 0.32 0.380 0.020 0.026 75 mM MOPA 12’ 12.73’ 12.96’ 13.14’ 13.63’ 3 75 mM Propanal 0.7 0.392 0.444 0.025 0.026 50 mM MOPA 12’ 12.73’ 12.96’ 13.14’ 13.63’ 4 50 mM Propanal 0.228 0.2 0.195 0.012 0.014 25 mM MOPA 12.01’ 12.73’ 12.96’ 13.13’ 13.64’ 5 25 mM Propanal 0.063 0.067 0.052 0.002 0.003 10 mM MOPA 12.0’ 12.74’ 12.96’ 6 n.d. n.d. 10 mM Propanal 0.048 0.052 0.028 50 mM MOPA 12’ 12.73’ 12.96’ 13.14’ 13.63’ 7 25 mM Propanal 0.065 0.12 0.1 0.006 0.008 25 mM MOPA 12’ 12.73’ 12.96’ 13.14’ 13.63’ 8 50 mM Propanal 0.224 0.117 0.105 0.006 0.007 25 mM MOPA 12’ 12.73’ 12.96’ 13.13’ 13.63’ 9 100 mM Propanal 1.109 0.153 0.157 0.010 0.010 100 mM MOPA 12’ 12.73’ 12.96’ 13.13’ 13.63’ 10 25 mM Propanal 0.038 0.148 0.136 0.009 0.010 pA = picoAmperes A corresponding graphical illustration is presented in attached Figure 6. For compounds 6 and 7, the sum of the 1stand 2ndpeak corresponding to the respective 2 different diastereomers is depicted. As can be seen, and excess of MOPA favors the formation of a compound (6), and excess of propanal favors the formation of compound (8). 4.5 Investigating the conversion of mixtures of Propanal (4b) and 2- Methylbutanal (5b) Reaction media were prepared as described above in section 3.1.2 containing 2- methylbutanal and propanal in different proportions. The carboligation reaction was catalysed by the triple mutant gstTK47. Composition of the obtained reaction mixture was analysed by GC. In each case the homocoupling product (8) and a heterocoupling product (6 and 7) was obtained. GC data are shown in Figure 7. 4.6 Investigating the conversion of mixtures of alpha-Ketobutyrate (4a) and MOPA (5a) Reaction media were prepared as described above in section 3.1.4 containing the donor acids alpha-ketobutyrate and MOPA in different proportions. The carboligation reaction was catalysed by the triple mutant gstTK47. Composition of the obtained reaction mixture was analysed by GC. In each case the homocoupling product (8) and a heterocoupling product (6 and 7) was obtained. GC data are shown in Figure 8 Herein above the following short names as depicted in Table 5 were used to designate the respective transketolase mutants of different origin: Table 5: Short name Mutation gstTK1 H68G gstTK7 H102M gstTK12 H28T gstTK20 H102L H474N gstTK21 L118F H474N gstTK24 H102V L118F H474D gstTK27 H102Y H474N gstTK28 "-" gstTK29 L382N / D470S gstTK30 L382D / D470S gstTK31 L382N / D470T gstTK32 L382E / D470T gstTK33 D470S gstTK34 D470T gstTK47 H102L / L118I / H474S gstTK48 H102L / L118I ecTK1 - ecTK6 H100L / L116I ecTK7 H100L / L116I / H473S ecTK8 H26T ecTK9 H66A ecTK10 H66G ecTK11 H100L Table 6: Assignment of SEQ ID NOs: SEQ ID NO: Description Type 1 gstTK WT NA 2 gstTK (N-His Tag) WT AA 3 gstTK H28T NA 4 gstTK (N-His Tag) H28T AA 5 gstTK H68G NA 6 gstTK (N-His Tag) H68G AA 7 gstTK H102L / L118I NA 8 gstTK (N-His Tag) H102L / L118I AA SEQ ID NO: Description Type 9 gstTK H102L / L118I / H474S NA 10 gstTK (N-His Tag) H102L / L118I / H474S AA 11 gstTK H102M NA 12 gstTK (N-His Tag) H102M AA 13 gstTK H102L / H474N NA 14 gstTK (N-His Tag) H102L / H474N AA 15 gstTK L118F / H474N NA 16 gstTK (N-His Tag) L118F / H474N AA 17 gstTK H102V / L118F / H474D NA 18 gstTK (N-His Tag) H102V / L118F / H474D AA 19 gstTK H102Y / H474N NA 20 gstTK (N-His Tag) H102Y / H474N AA 21 gstTK L382N / D470S NA 22 gstTK (N-His Tag) L382N / D470S AA 23 gstTK L382D / D470S NA 24 gstTK (N-His Tag) L382D / D470S AA 25 gstTK L382N / D470T NA 26 gstTK (N-His Tag) L382N / D470T AA 27 gstTK L382E / D470T NA 28 gstTK (N-His Tag) L382E / D470T AA 29 gstTK D470S NA 30 gstTK (N-His Tag) D470S AA 31 gstTK D470T NA 32 gstTK (N-His Tag) D470T AA 33 ecTK1 WT - NA 34 ecTK1 (His tag C term) WT AA 35 ecTK1 H26T NA 36 ecTK1 (His tag C term) AA 37 ecTK1 H66A NA 38 ecTK1 (His tag C term) AA 39 ecTK1 H66G NA 40 ecTK1 (His tag C term) AA 41 ecTK1 H100L NA 42 ecTK1 (His tag C term) AA 43 ecTK1 H100L / L116I NA 44 ecTK1 (His tag C term) AA 45 ecTK1 H100L / L116I / H473S NA 46 ecTK1 (His tag C term) AA 47 Thr DH E. coli (strain K12) NA 48 Thr DH E. coli (strain K12) AA 49 DAAO Rhodotorula gracilis WT NA 50 DAAO Rhodotorula gracilis WT AA 51 gskTK WT AA 52 Transaldolase WT of Thermoplasma acidophilum NA 53 Transaldolase WT of Thermoplasma acidophilum AA 54 Isoleucine racemase Lentilactobacillus buchneri NA 55 Isoleucine racemase Lentilactobacillus buchneri AA 56 ecTK1 WT - AA AA = amino acid sequence NA = nucleic acid sequence WT = wild type

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Claims

Claims 1. A biocatalytic process the production of aroma chemicals, which process comprises an enzyme catalyzed carboligation of a donor molecule (D) selected from 2-oxobutanoic acid (α-KB) and 3-methyl-2- oxopentanoic acid (MOPA) and an acceptor molecule (A) selected from propanal and 2-methylbutanal, in the presence of catalytic amounts of the coenzyme TPP; and the subsequent isolation of the obtained carboligation product, wherein said carboligation reaction is catalyzed by a transketolase (TK) (EC 2.2.1.1) 2. The biocatalytic process of claim 1, wherein said carboligation product is selected from 3-hydroxy-5-methyl-heptan-4-one, 4-hydroxy-5-methyl-heptan-3-one, 5- hydroxy-3,6-dimethyl-octan-4-one, and 4-hydroxy-hexan-3-one or a combination of at least two thereof, each either in stereoisomerically pure form or as a mixture of stereoisomers.

3. The biocatalytic process of anyone of the preceding claims, which further comprises the chemical dehydration of 3-hydroxy-5-methyl-heptan-4-one to 5- methyl-hept-2-ene-4-one in the presence of catalytic amounts of an acid, either in stereoisomerically pure form or as a mixture of stereoisomers.

4. The biocatalytic process of anyone of the claims 1 to 3, wherein a transketolase mutant is applied, wherein said mutant is selected from single, double or triple mutants of the G. stearothermophilus TK wild-type sequence according to SEQ ID NO:51; or of the E. coli. TK wild-type sequence according to SEQ ID NO:

56.

5. The biocatalytic process of claim 4, wherein the G. stearothermophilus TK mutant is selected from single mutants H68G, H102M, H28T, D470S and D470T double mutants H102L / H474N, L118F / H474N; H102Y / H474N, H102L / L118I, L382N / D470S; L382D / D470S; L382N / D470T and L382E / D470T; and triple mutants H102L / L118I / H474S and H102V / L118F / H474D, each derived from a TK sequence of SEQ ID NO:51, either with or without an N- terminal or C-terminal His tag motif, or a sequence having a degree of sequenceidentity of at least 70% thereto while retaining TK activity; or wherein the E.coli TK mutant is selected from single mutant H100L and double mutant H100L / L116I; each derived from a TK sequence of SEQ ID NO:56, either with or without an N- terminal or C-terminal His tag motif or a sequence having a degree of sequence identity of at least 70% thereto while retaining TK activity.

6. The biocatalytic process of anyone of the claims 4 or 5, wherein a TK mutant is applied which is selected from mutants having an amino acid sequence according to SEQ ID Nos: 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, , 42 or 44, , each either with or without an N-terminal or C-terminal His tag motif, and amino acid sequences having a degree of sequence identity of at least 70% to SEQ ID Nos: 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 42 or 44,, while retaining the respective mutation position or mutation positions and retaining the ability to catalyze anyone of the above identifies TK-catalyzed carboligation reactions.

7. The biocatalytic process of anyone of the preceding claims, further comprising the step of simultaneous or non-simultaneous enzyme catalyzed formation of anyone of the donor molecules (D), wherein 2-oxobutanoic acid (α-KB) is formed from (D / L)-threonine by the enzymatic action of a Threonine Dehydratase (ThrDH) (EC 4.3.1.19); and 3-methyl-2-oxopentanoic acid (MOPA) is formed from D-isoleucine by the enzymatic action of a D-Amino Acid Oxidase (DAAO) (EC 1.4.3.

3.

8. The biocatalytic process of claim 7, wherein said ThrDH comprises an amino acid sequence according to SEQ ID NO: 48, or a sequence having a degree of sequence identity of at least 70% thereto; and wherein said DAAO comprises an amino acid sequence according to SEQ ID NO: 50, or a sequence having a degree of sequence identity of at least 70% thereto.

9. A nucleic acid molecule encoding at least one TK mutant as defined in claim 5 or 6.

10. The nucleic acid molecule of claim 9 comprising a nucleotide sequence selected from SEQ ID Nos: 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 41 or 43 and nucleotide sequences having a degree of sequence identity of at least 70% to SEQ ID Nos: 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 41 or 43, while retaining the respective mutation position or mutation positions of the encoded TK mutant and retaining the ability of said mutant to catalyze anyone of the above identifies TK-catalyzed carboligation reactions.

11. An expression construct or a recombinant vector comprising under the control of at least one regulatory element the coding sequence for at least one TK mutant as defined in anyone of the claims 9 or 10.

12. The expression construct or the recombinant vector of claim 11 further comprising under the control of at least one regulatory element the coding sequence for a ThrDH and / or a DAAO and optionally a racemase.

13. A recombinant non-human host carrying at least one recombinant vector or at least one nucleic acid or at least one expression construct of anyone of the claims 9 to 12.

14. A biocatalytic process of anyone of claims 1 to 8, which comprises the cultivation of at least one recombinant host of claim 13 under conditions allowing the TK- catalyzed production of at least one carboligation product of claim 2 and isolating the same from the production medium.

15. Use of a compound as defined in claims 2 or 3 as an aroma chemical, in particular, to impart an aroma impression to a composition.