158 results about "Corynebacterium glutamicum" patented technology

The invention belongs to the technical field of synthetic biology, and particularly relates to recombinant escherichia coli for efficiently producing O-acetyl-L-homoserine as well as a construction method and application of the recombinant escherichia coli. According to the invention, CRISPR-Cas9 gene editing is combined with metabolic modification, so as to precisely integrate OAH biosynthesis key nodes: introducing and overexpressing a mutant metX gene at a genome pseudogene site to enhance the expression of homoserine acetyltransferase, knocking out byproducts such as poxB and mgsA to synthesize genes, and carrying out high-yield synthesis of OAH. Corynebacterium glutamicum thrA (anti-feedback inhibition), aspB and bacillus subtilis acsA-acuA genes (construction of an acetic acid switch) are introduced, gene expression of gltA, tpiA and the like is optimized to increase supply of precursors such as acetyl CoA and the like, and finally a stable strain without plasmids, antibiotics and inducers is obtained. The production cost is effectively reduced, and the method has the advantage of high genetic stability and shows a good application prospect in OAH industrial production.

The application discloses an Escherichia coli probiotic with high beta-alanine yield and application thereof, and the recombinant genetically engineered bacterium takes a wild-type Escherichia coli probiotic as a starting strain and is subjected to one or more gene edits, including Trc promoter strengthening of a panD gene, an aspC gene, an sdhC gene and a ppc gene, overexpression of a panD gene from Bacillus subtilis, an aspB gene from Corynebacterium glutamicum, an aspA gene and a pyc gene from Corynebacterium glutamicum on a plasmid pTrc99a, and knockout of a cycA gene. 600 Compared with an existing reported Escherichia coli probiotic beta-alanine production strain, the OD of the recombinant genetically engineered bacterium is 4.4 times that of the existing reported strain, and the beta-alanine yield is 6 times that of the existing reported strain, so that the recombinant genetically engineered bacterium has great industrial application potential.

The invention relates to the technical field of synthesis of natural dyes by a biological method, in particular to an antibiotic-demand-free ornamental blue high-yield strain as well as construction and application of the antibiotic-demand-free ornamental blue high-yield strain. Corynebacterium glutamicum is used as an initial strain, a tricarboxylic acid circulating gene is regulated and interfered, and the copy number of exogenous blue pigment synthetase BpsA in a genome is adjusted, so that the ornamental blue high-yield strain is obtained. The strain does not need to use antibiotics in the fermentation process, the yield is stable, the product production capacity equivalent to the level when antibiotics are used can still be achieved through fermentation under the antibiotic-free condition, and the growth performance of the strain is kept. The method for producing the ornamental blue by using the strain provided by the invention ensures that the ornamental blue product is natural and green, also improves the efficient production capacity of the strain, solves the contradiction between green environmental protection and stable high yield of the ornamental blue dye, is green and environment-friendly, and has a remarkable industrial application prospect.

The invention discloses a rigorous induction system for corynebacterium glutamicum and application of the rigorous induction system, and belongs to the fields of genetic engineering and microbiology. The system can be strictly regulated when an inducer is not added, and can express only after the inducer is added. More specifically, the invention relates to the reduction of leak expression of Cre recombinase by comprising a logic gate, repression regulation and RNA regulation elements, and the use thereof for mediating SCRaMbLE to produce large-scale genome random rearrangement in Corynebacterium glutamicum synthetic genomes. Particularly, the method is used for reducing the leakage expression level of Cre recombinase and keeping the moderate expression level after induction. More importantly, the rigorous induction system disclosed by the invention can be applied to genome rearrangement to obtain rearranged strains with highly diversified genotype sequences, so that the purpose of increasing the yield of target products or enhancing the stress resistance of the strains is achieved.

The invention relates to the field of synthetic biology, metabolic engineering and fermentation engineering, and discloses a genetically engineered bacterium and application thereof in production of alpha-ketoglutaric acid.The genetically engineered bacterium comprises the steps that the genetically engineered strain with escherichia coli BW25113 or corynebacterium glutamicum ATCC13032 as a host is constructed; overexpression type isocitrate dehydrogenase genes are integrated through chromosomes, alpha-ketoglutarate dehydrogenase complex genes are knocked out, NADPH invertase is overexpressed through plasmids, and exogenous AKG transporter protein is introduced, so that metabolic flux directional regulation and control and product efflux enhancement are realized; meanwhile, a staged fermentation process is adopted and comprises dynamic gradient adjustment of inorganic phosphorus concentration and two-stage pH control. According to the method, the AKG yield of 78.2 g / L can be obtained under the 5L tank scale, the sugar acid conversion rate reaches 0.68, and the method has the advantages of being high in yield, low in byproduct and controllable in cost. The obtained AKG is suitable for a plurality of fields such as medical intermediates, functional foods and cell culture additives, and has wide industrial application prospects.

The invention provides a strain for producing L-2-aminobutyric acid as well as a construction method and application of the strain. According to the strain, E.coli W3110 is taken as a chassis strain, tdh, rhtA and ilvE genes are knocked out, the transcriptional levels of ppc, aspC, thrAfbrBC, ilvAfbr, tdcB, yaS and pntAB genes are up-regulated, an ilvI gene is weakened, bcd and gdh genes derived from bacillus subtilis B.subtilis 168 and a cysK gene derived from Corynebacterium glutamicum K051 are introduced in a heterologous manner, and the L-2-aminobutyric acid producing strain is obtained through screening and screening. The strain does not contain plasmids, is stable in heredity, does not need induction, does not need to add resistant substances, efficiently synthesizes L-2-aminobutyric acid from the beginning by taking glucose as a substrate, and has good L-2-aminobutyric acid synthesis capability, stable performance and high acid production efficiency.

The invention discloses a screening and expression platform construction method for non-essential gene loci of corynebacterium glutamicum, and belongs to the technical field of biology. The center sites CGLRS02940, CGLRS03085, CGLRS08555, CGLRS09020 and CGLRS13560 of the corynebacterium glutamicum identified by the invention have the remarkable advantages that when gene knockout or knockin operation is carried out, the sites do not interfere with the normal physiological metabolism process of strains, and stable expression of exogenous genes can be guaranteed; meanwhile, the gene editing efficiency is relatively high, and an editing target with high universality and high reliability is provided for genetic engineering modification of corynebacterium glutamicum.

The present invention relates to a Corynebacterium glutamicum mutant strain having increased L-citrulline productivity, and a method of producing L-citrulline using the same. The Corynebacterium glutamicum mutant strain is capable of producing L-citrulline in high yield and high concentration while inhibiting the production of by-products, because the activity of the protein that is expressed by the NCgl2657 gene therein has been weakened or inactivated.

This invention relates to the fields of microbial genetic engineering and fermentation biomanufacturing technology, specifically disclosing a recombinant Corynebacterium glutamicum with high 5-aminolevulinic acid (ALA) production and its applications. Addressing the problems of existing strains such as crude enzyme activity regulation, inhibited cell growth, the need for external inhibitors, and low yield, this invention uses Corynebacterium glutamicum as a host and removes the gdhA gene without scarring to reduce precursor competitive metabolism. Site-directed mutations of the endogenous hemB gene (S288A, D128E, R231K) are performed to moderately reduce dehydratase activity. A high-expression plasmid pXMJ19-hemA containing the hemA gene from Rhodopsinus capsulatum is constructed and introduced into the modified strain to obtain a recombinant strain with optimized triple metabolism. This strain reduces product degradation without the need for external dehydratase inhibitors, does not affect cell growth, and achieves a yield up to 4.30 times higher than the control after 42 hours of fermentation, with ALA accumulation exceeding 8.9 g / L. The strain exhibits stable characteristics, the process is simple, and it has good industrial application value.

This invention relates to a pyridoxal phosphate-responsive biosensor and its application, belonging to the field of synthetic biology biosensor technology. This invention is the first to discover and identify the relationship between pyridoxal phosphate and Cgl1185-P. cgl2838 The transcriptional regulation and response relationship between these factors was investigated, and this relationship was used as the basis for constructing a biosensor responsive to pyridoxal. The transcription factor regulatory system Cgl1185-P derived from Corynebacterium glutamicum was used. cgl2838 A biosensor for the specific detection of pyridoxal phosphate was constructed by assembling a reporter gene as the main component onto a plasmid, enabling effective detection of pyridoxal phosphate concentrations in intracellular or culture environments. This biosensor possesses advantages such as clear structure, high sensitivity, and good host adaptability, and can be used for fermentation process monitoring, cofactor metabolism research, and screening of relevant strains, showing promising application prospects in the fields of cofactor concentration monitoring and metabolic regulation.

The application discloses a construction method and application of a genetically engineered corynebacterium glutamicum for synthesizing a bacteriochlorophyllide amino acid shinorine, and belongs to the field of genetic engineering and fermentation technology. The genetically engineered corynebacterium glutamicum is constructed by taking corynebacterium glutamicum ATCC 13032 as a host strain, knocking out a competitive pathway gene, integrating a key enzyme gene in multiple copies on a genome, knocking out an acid production pathway gene and a serine dehydrogenase gene, and expressing a gene cluster for synthesizing shinorine on a plasmid, so that the synthesis yield of shinorine in a microbial cell is improved. The strain can produce shinorine in a flask, and 1.12 g / L of shinorine can be accumulated in 72 hours. In fed-batch fermentation in a 50 L fermenter, the strain can be cultured to 8.6 g / L.

The invention relates to Corynebacterium glutamicum with high indigo yield as well as a construction method and application thereof, and belongs to the technical field of gene recombination fermentation. The recombinant corynebacterium glutamicum can be used for overexpression of the following genes: a D-glucose-6-phosphate dehydrogenase gene zwf, a II type deoxyarabinose type heptulose phosphate synthase gene aroG and a flavin-containing monooxygenase gene CcFMO. The recombinant corynebacterium glutamicum can weaken the following genes: a pyruvate kinase gene pyk and a tryptophan synthase gene trpB. The corynebacterium glutamicum is used for overexpressing a zwf gene, an aroG gene and a CcFMO gene, weakening a pyk gene and a trpB gene and enhancing the expression quantity of an indole synthetic pathway related enzyme gene, so that the yield of the corynebacterium glutamicum at a shake flask stage reaches 619mg / L in a fermentation production process of indigo under the condition of not additionally adding tryptophan. The invention provides the recombinant corynebacterium glutamicum with high indigo yield, which is low in production cost, good in stability and high in synthesis efficiency, and is suitable for practical popularization and application.

The invention discloses a genetically engineered bacterium for efficiently producing D-pantothenic acid as well as a construction method and application of the genetically engineered bacterium, the construction method comprises the following steps: (a) taking corynebacterium glutamicum DPA2 as a chassis bacterium, enhancing the expression of at least one pantothenic acid main pathway gene in a chassis bacterium genome, and introducing plasmid pEC-XK99E-panBCilvC to obtain an engineered strain for modifying the pantothenic acid main pathway gene; (b) knocking out at least one heteroacid pathway gene in the engineering strain obtained in the step (a), carrying out in-situ integration on a panBCC gene at an alaT gene locus, and introducing a plasmid pEC-XK99E-panBCilvC to obtain a heteroacid pathway modified engineering strain; and (c) knocking out the pyruvic acid shunt gene pyc in the heteroacid pathway modified strain obtained in the step (b), enhancing the expression of an odx gene, and introducing a plasmid pEC-XK99E-panBCilvC to obtain the engineering strain for regulating and controlling the pyruvic acid shunt. The genetically engineered bacterium has the beneficial effects that the genetically engineered bacterium for efficiently producing D-pantothenic acid is obtained, and the yield and the conversion rate are higher; the level of the modified strain in the aspect of fermentation production of D-pantothenic acid is obviously improved.

The invention relates to a method for efficiently synthesizing lysine by corynebacterium glutamicum based on multi-level metabolism reconstruction, and belongs to the technical field of metabolic engineering. The method is not limited to single gene or single path transformation, but carries out system integrated regulation and control from multiple levels of lysine main synthesis pathway, central carbon metabolism redistribution, by-product synthesis inhibition and lysine transport and tolerance mechanism, and constructs a ''flux-energy-tolerance'' synergistically matched integral metabolism network; the method is a fundamental technical framework for realizing 240g / L high yield. On the premise that genetic stability of engineering bacteria and controllability of the fermentation process are guaranteed, stable and efficient synthesis of lysine under the high-density fermentation condition is achieved, the final fermentation concentration of lysine stably reaches 240 g / L or above, meanwhile, high carbon source conversion efficiency and low by-product generation level are both considered, and the method is suitable for industrial production. Therefore, the technical bottleneck that the existing lysine biological manufacturing technology is limited to the platform stage of yield of about 200 g / L for a long time is broken through.

The present application provides a novel protein or polynucleotide variant, a Corynebacterium glutamicum strain containing the protein or polynucleotide variant, and a method for producing L-lysine using the strain.

Methods for producing organosulfur compounds from a prokaryotic cell comprising enzymes involved in the production of cysteamine, hypotaurine, and taurine. Said prokaryote may comprise a vanin selected from vanin-1 (vnn-1), vanin-2 (vnn-2), or vanin- 3 (vnn-3), a cysteamine dioxygenase (ado), and / or a flavin-containing monooxygenase 1 (fmo1). Methods include the expression of organosulfur compounds in Corynebacterium glutamicum with incubation conditions to promote compound production.

The invention discloses genetically engineered corynebacterium glutamicum and an application of the genetically engineered corynebacterium glutamicum in preparation of ectoine, and the genetically engineered corynebacterium glutamicum contains an L-diaminobutyric acid transaminase gene ectB, an L-diaminobutyric acid acetyltransferase gene ectA and an ectoine synthetase gene ectC, the invention relates to an aspartic acid transferase gene aspB, an aspartic acid kinase gene lysC and an aspartic acid semialdehyde dehydrogenase gene asd, wherein the nucleotide sequences of the gene aspB, the gene lysC and the gene asd are respectively as shown in SEQ ID NO.4, SEQ ID NO.5 and SEQ ID NO.6. The invention further discloses a preparation method of the aspartic acid transferase gene aspB, the aspartic acid kinase gene lysC and the aspartic acid semialdehyde dehydrogenase gene asd. After the recombinant corynebacterium glutamicum constructed by the invention is fermented for 60 hours, the yield of ectoine can reach 50g / L. The genetically engineered corynebacterium glutamicum disclosed by the invention has important practical significance on industrial production and large-scale application of ectoine.

The invention relates to a hyaluronic acid high-yield strain based on metabolic flow optimization as well as a construction method and application thereof, and belongs to the technical field of genetic engineering. According to the corynebacterium glutamicum, sources of key rate-limiting enzymes UDP-glucose dehydrogenase and glutamine-fructose-6-phosphate aminotransferase are screened, and heterologous expression of hyaluronic acid synthase and overexpression of endogenous inositol permease and glucokinase are combined, so that the corynebacterium glutamicum capable of highly producing hyaluronic acid is constructed in a form of optimizing metabolic flux; according to the invention, the hyaluronic acid is used as a substrate, polyhydroxybutyrate synthase clusters are further overexpressed in the substrate, the glucose uptake and utilization efficiency of a host are improved, the metabolic coupling of cofactors is realized, the yield of the hyaluronic acid reaches 45g / L, the production intensity is 1.25 g / L / h, a brand new tool is provided for the production of the hyaluronic acid, and the method has an excellent application prospect.

The invention belongs to the technical field of synthetic biology and fermentation engineering, and discloses an engineering bacterium for producing Indigoidine based on membrane vesicle engineering reinforced corynebacterium glutamicum and application of the engineering bacterium. According to the invention, the ncp1 gene of corynebacterium glutamicum is knocked out through a CRISPR-Cas12a gene editing technology, connection between cell walls and cell membranes is relieved, and a chassis strain of high-yield extracellular membrane vesicles (OMVs) is constructed; meanwhile, a recombinant expression vector is introduced, indigo synthetase BpsA is positioned and displayed on membrane vesicles by utilizing PorB anchoring protein, and activating enzyme Sfp is co-expressed. In fermentation production, a staged feeding and IPTG (isopropyl-beta-d-thiogalactoside) and Tween-80 dual induction strategy is adopted to promote thalli to express zymoprotein and release a large number of membrane vesicles at the same time. According to the method, the membrane vesicles are used as an extracellular microreactor, so that the'simultaneous synthesis and secretion 'of the indissolvable indigo is realized, the problems of cytotoxicity and metabolic inhibition caused by intracellular precipitation of the product are effectively solved, and the yield and extraction efficiency of the indigo are remarkably improved.

This invention discloses a method for the efficient synthesis of gastrodin using recombinant Corynebacterium glutamicum, belonging to the fields of genetic engineering, fermentation engineering, and synthetic biology. This invention uses Corynebacterium glutamicum as the host bacterium and knocks out… pobA The gene was expressed, and the engineered strain WN01 / pB6 was constructed using the expression plasmid pEC-XK99E to express cladoid-pyruvate lyase, carboxylic acid reductase, and glycosyltransferase, achieving heterologous synthesis of gastrodin. Further overexpression was then performed. aroG Genes, overexpression of protein-coding genes that activate carboxylic acid reductase sfp The engineered strain WN05 / pB6 was able to synthesize 7.37 g / L of gastrodin at the shake flask level, and the gastrodin yield reached 17.77 g / L at 72 h of batch fermentation in a 5-L fermenter, with a yield of 0.247 g / L / h. This provides a brand-new biomanufacturing platform for the industrial production of gastrodin.

The present invention provides recombinant Corynebacterium glutamicum genetically engineered to introduce the N-acetylmannosamine (ManNAc) synthesis pathway, and genetically engineered to express an exogenous N-acetylneuraminic acid synthetase, an exogenous CMP-N-acetylneuraminic acid synthetase, an exogenous lactose transporter, and an exogenous sialyltransferase. The invention also provides a method for producing sialic acid lactose by using the recombinant corynebacterium glutamicum.

The invention discloses a nitrilase mutant and an application technology thereof in synthesis of nicotinic acid, and belongs to the technical fields of gene engineering, enzyme engineering and biological catalysis. The nitrilase mutant disclosed by the invention is obtained by mutating nitrilase from a source of Pseudomonas putida CGMCC (China General Microbiological Culture Collection Center) 3830, and the heterologous expression of the nitrilase mutant in corynebacterium glutamicum is successfully realized. The optimal mutant can efficiently catalyze a substrate 3-cyanopyridine to synthesize 550.68 g / L of nicotinic acid, and the conversion rate is 91.37%.

The invention discloses a genetically engineered bacterium for producing D-pantothenic acid based on a corynebacterium glutamicum CPSPC system as well as a construction method and application of the genetically engineered bacterium. Wild type C.glutamicum ATCC 13032 is taken as a chassis strain, and a functional combination of a glycine ribosome switch BsGR from bacillus subtilis and a promoter Ptuf / Ph36 is verified through fluorescent protein mCherry; a GCS system of escherichia coli and bacillus subtilis is introduced to the strain DPAg-15, genes related to synthesis of 5, 10-dimethyltetrahydrofolic acid are tested, it is found that serA delta197GTG / ATG significantly increases the yield of D-pantothenic acid, the yield of D-pantothenic acid of the constructed strain DPAj-2-tuf is increased to 23.06 g / L (63 h), the yield is 0.37 g / L / h, and the conversion rate is 0.17 g / g; the engineering strain DPAj-2-tuf is obtained by dynamically regulating and controlling a D-pantothenic acid synthesis path through a CPSPC system and combining plasmid overexpression serA delta197GTG / ATG, the yield of the engineering strain DPAj-2-tuf is increased by 2.1 times compared with that of a traditional method, and an efficient technical scheme is provided for producing D-pantothenic acid through a microbial fermentation method.

This invention provides an engineered bacterium for producing ectoine, its preparation method, and its application. The engineered bacterium is prepared using a method comprising the following steps: using *Corynebacterium glutamicum* as the starting strain, feedback inhibition by aspartate kinase LysC is relieved, the activity of the gene lysE encoding lysine efflux permease is reduced, and the ectoine synthesis gene cluster ectABC is expressed. Based on this, the activity of any one or at least two of the following—diaminobutyrate acetyltransferase EctA, pyruvate carboxylase Pyc, or aspartate kinase LysC—is enhanced, and / or the activity of any one or at least two of the following—maloquinone oxidoreductase Mqo or homoserine dehydrogenase Hom—is reduced to further increase ectoine yield.

The application discloses an expression vector of a biosynthetic metabolic pathway gene of 2-azacyclohexanone and a synthesis method of 2-azacyclohexanone. The expression vector comprises a first promoter and, sequentially inserted downstream of the first promoter, davA-davB genes or davB-davA genes, a Pb promoter or a mutant thereof, an act gene or an orf26 gene or a caiC gene, a ChnR gene or a mutant thereof. The expression vector is further transferred into glutamic acid corynebacterium with high lysine yield, and is subjected to fermentation culture to efficiently synthesize 2-azacyclohexanone. The application synthesizes 2-azacyclohexanone in glutamic acid corynebacterium for the first time, and utilizes an optimized 2-azacyclohexanone molecular probe system to start the expression of key genes in the 2-azacyclohexanone biosynthetic metabolic pathway for the first time, so that high yield of 2-azacyclohexanone is realized. The synthesis method reduces the production cost required by using lysine as a synthesis raw material, eliminates a rate-limiting step, and greatly improves the biosynthesis yield of 2-azacyclohexanone.

The invention provides a compound microbial agent for water treatment as well as a preparation method and application thereof, and belongs to the technical field of circulating cooling water treatment. The compound microbial agent for water treatment is prepared from the following components in parts by weight: 10 to 30 parts of bacillus subtilis bacterial liquid, 50 to 70 parts of corynebacterium glutamicum bacterial liquid and 20 to 40 parts of lactobacillus rhamnosus bacterial liquid. The bacillus subtilis liquid, the corynebacterium glutamicum liquid and the lactobacillus rhamnosus liquid are utilized, so that the corrosion rate can be reduced, the corrosion inhibition rate can be remarkably improved, the corrosion inhibition rate reaches 81.71%, the scale inhibition efficiency on CaCO3 reaches 100%, the dirt deposition rate during circulating cooling water treatment can be remarkably reduced, and good corrosion inhibition performance and scale inhibition performance are achieved. The corrosion and scale inhibition method for the circulating cooling water is simple and easy to operate. The invention lays a foundation for treating circulating cooling water by applying a biological method on a large scale.

The present application relates to the technical field of genetic engineering, and discloses a genetically engineered bacterium for high-yield D-pantothenic acid, a construction method and application.The genetically engineered bacterium for high-yield D-pantothenic acid is obtained by knocking out an ilvA gene in Corynebacterium glutamicum ATCC 13032 to reduce the consumption of pyruvic acid for isoleucine generation, overexpressing a 3-methyl-2-oxobutyric acid hydroxymethyltransferase gene panB and a pantothenate synthetase gene panC in a pantothenic acid synthesis pathway, and heterologously overexpressing a pantothenate reductase panE from Escherichia coli to further improve the yield of D-pantothenic acid in the Corynebacterium glutamicum ATCC 13032.

The invention discloses a method for reducing the molecular weight of gamma-PGA based on a polycistron expression vector, which comprises the following steps: cloning a gamma-polyglutamic acid synthetase gene cluster pgsBCA of bacillus licheniformis into corynebacterium glutamicum F343 with high yield of glutamic acid in a polycistron expression mode for exogenous expression to obtain a recombinant strain pBCA; compared with a recombinant strain pBpCpA expressed by a monocistron, the recombinant strain pBCA carrying a polycistron expression system has the advantage that the molecular weight of gamma-PGA generated by the recombinant strain pBCA is reduced by 15.98%. Therefore, the polycistron expression system is an effective method for reducing the molecular weight of the gamma-PGA.

The application discloses a method for increasing 2-pyrrolidone synthesis and belongs to the technical field of bioengineering. tacm The CoA transferase from Butyricicoccus faecihominis is expressed in the coryneform bacterium glutamicum, and the CoA transferase is secreted and expressed by means of P The promoter and the NS signal peptide strengthen the secretory expression of the CoA transferase, so that the constructed strain can ferment 2-pyrrolidone in a glucose carbon source and in a pH 7.0 environment, and the yield of the 2-pyrrolidone can reach 12.13 g / L in 96 h of flask fermentation.

The present application relates to a kind of acetolactate synthase and its application, belong to enzyme engineering and metabolic engineering technical field.The present application is based on the wild-type acetolactate synthase from Corynebacterium glutamicum (Corynebacterium glutamicum) Corynebacterium glutamicum ) ATCC13032, the encoding gene ilvBN Of it is carried out error-prone PCR, screening obtains acetolactate synthase mutant IlvBN M1 And IlvBN M2 , above-mentioned mutant removes L-valine, L-leucine and L-isoleucine on its feedback inhibition, under the condition that L-valine, L-leucine and L-isoleucine concentration is 0-30 mmol / L respectively, enzyme activity has no obvious change, can be widely used in the synthesis of L-valine, L-leucine and L-isoleucine.