48 results about "Pyruvate formate lyase" patented technology

The invention discloses an XZ-A26 bacterial strain for producing L-alanine with high yield, which has a preservation number of CGMCC (China General Microbiological Culture Collection Center) No.4036 and has the capacity of generating high-concentration L-alanine through fermentation. The XZ-A26 bacterial strain is constructed by the steps of: integrating an L-alanine dehydrogenase gene on thermophilic fatty bacillus chromosome on lactic dehydrogenase position on an escherichia coli ATCC8739 chromosome, then sequentially knocking out a pyruvate formate lyase gene, an alcohol dehydrogenase gene, an acetokinase gene, a fumaric acid reductase gene and an alanine racemase gene of the escherichia coli chromosome, and then carrying out continuous cell culture in a fermenting tank for obtaining agenetic engineering strain. The invention also relates to a construction method of the XZ-A26 bacterial strain and an application of the XZ-A26 bacterial strain in preparation of the L-alanine. According to the invention, the escherichia coli with the preservation number of CGMCC No.4036 for generating the high-concentration L-alanine through fermentation can be constructed by using a metabolic engineering method, and the yield of the L-alanine generated by using the XZ-A26 bacterial strain reaches up to 115g / L. The XZ-A26 bacterial strain is suitable for industrially producing the L-alanine.

Provided are novel rumen bacterial mutants resulted from the disruption of a lactate dehydrogenase gene (ldhA) and a pyruvate formate-lyase gene (pfl) from rumen bacteria; a novel bacterial mutant (Mannheimia sp. LPK7) having disruptions of a ldhA, a pfl,a phosphotransacetylase gene (pta), and a acetate kinase gene (ackA); a novel bacterial mutant (Mannheimia sp. LPK4) having disruptions of a ldhA, a pfl, and a phosphoenolpyruvate carboxylase gene (ppc) involved in the immobilization of CO2 in a metabolic pathway of producing succinic acid; and a method for producing succinic acid, characterized by culture of the above mutants in anaerobic conditions. The bacterial mutants have the property of producing succinic acid at high concentration while producing little or no organic acids, as compared to the prior wild-type strains of producing various organic acids. Thus, the bacterial mutants are useful as strains for the industrial production of succinic acid.

Mutants of lactic acid bacteria including Lactococcus lactis which are defective in pyruvate formate-lyase production and / or in their lactate dehydrogenase (Ldh) production and methods of isolating such mutants or variants are provided. The mutants are useful in the production of food products or in the manufacturing of compounds such as diacetyl, acetoin and acetaldehyde and as components of food starter cultures.

A thermophilic microorganism lacks lactate dehydrogenase activity and preferably contains an active pyruvate formate lyase pathway. The thermophilic microorganism contains a gene encoding an NAD-linked formate dehydrogenase. The gene encoding an NAD-linked formate dehydrogenase is preferably a codon optimised version of the gene encoding a thermostable NAD-linked formate dehydrogenase. DNA constructs allow stable expression of the gene encoding an NAD-linked formate dehydrogenase in the thermophilic microorganism. The DNA constructs are based upon use of an insertion sequence to achieve stable expression or recombination to insert the gene encoding an NAD-linked formate dehydrogenase into the lactate dehydrogenase gene, thus achieving gene knockout and new functionality in a single step. The microorganisms are useful in fermentation of sugars to produce ethanol.

The invention discloses a genetic engineering bacterium for synthesizing pyruvic acid and D-alanine as well as a construction method and application thereof. Recombinant escherichia coli of the invention is obtained by knocking out apyruvate dehydrogenase complex achEF gene, a pyruvate lyase pflB gene, a pyruvate oxidase poxB gene, a phosphoenolpyruvate synthase pps gene and a lactic dehydrogenaseldhA gene in escherichia coli BL21 (DE3), blocking a key pathway of further metabolism of pyruvic acid and knocking out genes btsT and cstA for encoding a pyruvic acid transport protein. For the genetic engineering bacterium disclosed by the invention, L-amino acid deaminase pm1 is utilized to catalyze D, L-alanine, so that L-alanine can be converted to the pyruvic acid and can be separated to obtain D-alanine at the same time, and a new idea and method is provided to chiral separation of the D, L-alanine; and the recombinant escherichia coli capable of efficiently synthesizing the pyruvic acid and the D-alanine is obtained through modification, the yield of the pyruvic acid reaches 32.0g / L, the conversion rate of the L-alanine reaches up to 80 percent, and the separation rate of the D / L-alanine reaches up to 80 percent.

The present invention relates to bacterial strains, capable of utilizing glycerol as a carbon source for the fermentative production of succinic acid, wherein said strains are genetically modified so that they comprise a deregulation of their endogenous pyruvate-formate-lyase enzyme activity, as well as to methods of producing organic acids, in particular succinic acid, by making use of such microorganism. The present invention also relates to the downstream processing of the produced organic acids by cation exchange chromatography.

A thermophilic microorganism lacks lactate dehydrogenase activity and preferably contains an active pyruvate formate lyase pathway. The thermophilic microorganism contains a gene encoding an NAD-linked formate dehydrogenase. The gene encoding an NAD-linked formate dehydrogenase is preferably a codon optimised version of the gene encoding a thermostable NAD-linked formate dehydrogenase. DNA constructs allow stable expression of the gene encoding an NAD-linked formate dehydrogenase in the thermophilic microorganism. The DNA constructs are based upon use of an insertion sequence to achieve stable expression or recombination to insert the gene encoding an NAD-linked formate dehydrogenase into the lactate dehydrogenase gene, thus achieving gene knockout and new functionality in a single step. The microorganisms are useful in fermentation of sugars to produce ethanol.

The invention discloses an XZ-A26 bacterial strain for producing L-alanine with high yield, wherein the preservation number is CGMCC No.4036. The XZ-A26 bacterial strain has the ability of fermenting to produce high-concentration L-alanine and is genetic engineering bacteria prepared by integrating the L-alanine dehydrogenase gene on Escherichia Coli chromosome of a lipase gene from Geobacillus Stearothermophilus at the lactic dehydrogenase of Escherichia coli ATCC 8739 chromosome, then sequentially removing a pyruvate formate-lyase gene, an ethanol dehydrogenase gene, an acetokinase gene, a fumarate reductase gene and an alanine racemase gene of the escherichia coli chromosome and then continuously subculturing in a fermentation tank. The invention also relates to a construction method of the bacterial strain and the application of the bacterial strain in preparing the L-alanine. According to the metabolic engineering method, the escherichia coli CGMCC No.4036 capable of fermenting to produce the high-concentration L-alanineis constructed, and the yield of the L-alanine produced by fermenting the bacterial strain is as high as 115g / L. The invention is suitable for the industrial production of L-alanine.

The invention discloses a recombination strain for an enterobacterium and application of the recombination strain for the enterobacterium. The recombination strain provided by the invention is a recombination strain obtained after deactivation of a pyruvate formate-lyase gene in the enterobacterium. As shown by experiments, the amount of by-product CO2 produced during the fermentation process of the recombination strain is obviously reduced and the amount of target products is obviously improved compared with the control. For example, the amount of lactic acid, the amount of succinic acid and the amount of 2, 3-butanediol produced by fermentation of klebsiella oxytoca are respectively improved by 30 percent, 9 percent and 23 percent compared with the control, and the amount of the CO2 produced is only 8.04 percent compared with the control. The recombination strain helps to release the pressure of the greenhouse effect, has important function in the actual industrial production,not only can greatly reduce the yield of the CO2, but also can improve the conversion rate of converting substrates into products, and has wide application prospect.

Mutants of lactic acid bacteria including Lactococcus lactis which are defective in pyruvate formate-lyase production and / or in their lactate dehydrogenase (Ldh) production and methods of isolating such mutants or variants are provided. The mutants are useful in the production of food products or in the manufacturing of compounds such as diacetyl, acetoin and acetaldehyde and as components of food starter cultures. In particular, Lactococcus lactis DN223 deposited under the accession No. DSM 11036.

Microorganisms that co-consume glucose with non-glucose carbohydrates, such as xylose, and methods of using same. The microorganisms comprise modifications that reduce or ablate the activity of a phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system (PTS) protein or modifications that reduce or ablate the activity of a phosphoglucose isomerase and a GntR. The PTS protein may be selected from an enzyme I (EI), an HPr, an FPr, and an enzyme IIGlc (EIIGlc). Additional modifications include reduction or ablation of the activity of a pyruvate formate lyase, a lactate dehydrogenase, and a fumarate reductase and inclusion of recombinant pyruvate decarboxylase and alcohol dehydrogenase genes. The microorganisms are particularly suited to co-consuming glucose and xylose in media containing these substrates and producing ethanol therefrom.

The invention discloses a genetic engineering strain capable of producing succinic acid at a low pH value. The classification name of the genetic engineering strain is Escherichia coli BA601, and the collection number is CCTCCNO: M2014210. The invention further discloses a method for producing succinic acid by using the strain. According to the strain disclosed by the invention, an Escherichia coli AFP111 which is lack of lactate dehydrogenase (LDH) genes and has activity of pyruvate formate lyase (PFL) genes and ptsG spontaneous mutation of a phosphotransferase system is taken as a starting strain for over-expression of acid-resistant genes gadBC. The method of enabling the Escherichia coli AFP111 which can not grow under low-pH (pH 5.6) conditions originally and can not produce acid by fermentation to efficiently utilize glucose to produce succinic acid through a biological and microbial acclimation means is not disclosed before, and the application can greatly promote the progress and development of the succinic acid industry.

An isolated microorganism is disclosed being genetically modified to express pyruvate formate lyase (PFL) or 2-ketobutyrate formate lyase, wherein acetyl-CoA of the microorganism is converted to pyruvate in the presence of formate in a single step reaction, wherein the net flux of the reaction is in the direction of pyruvate synthesis.Uses of the microorganism and products comprising same are also disclosed.

Fermentation processes for production of ethanol include supplying a thermophilic microorganism lacking lactate dehydrogenase activity with sugars under conditions in which they metabolise them predominantly by the pyruvate-formate lyase pathway. Importantly, the processes also include supplying sufficient glycerol to convert all of the sugars to ethanol. A further embodiment of the invention includes supplying additional glycerol sufficient to convert the exogenous acetate present in biomass hydrolysates into ethanol. Any type of fermentation system can be used for these processes, but a preferred embodiment includes continuous cultures at high temperatures in which ethanol is removed continuously by vacuum evaporation.

The invention discloses escherichia coli for producing isobutanol and ethanol and a preparation method of the escherichia coli. The invention provides a method for constructing recombinant bacteria for producing isobutanol and / or ethanol, wherein the method comprises the following steps: 1) expressing an ethanol dehydrogenase adhE and a pyruvate formate-lyase coding gene pflB in the escherichia coli AS108, so as to obtain a recombinant bacterium which is named as A; and 2) reducing enzymatic activity of ethanol dehydrogenase in the recombinant bacterium which is named as A and / or improving enzymatic activity of glucose-6-phosphate dehydrogenase in the recombinant bacterium which is named as A, so as to obtain a recombinant bacterium which is named as B. Experiments prove that excessive NADH can be consumed through a mode of introducing ethanol production in the AS108 strain based upon researches, so that toxicity to cells due to accumulation of the NADH is relieved; and meanwhile, NADPH supply can be promoted by activating a pentose phosphate pathway (PPP), so that an isobutanol production capacity is improved.

The present invention relates to a mutant microorganism, which is selected from the group consisting of genus Mannheimia, genus Actinobacillus and genus Anaerobiospirillum, producing homo-succinic acid and a method for producing homo-succinic acid using the same, and more particularly to a mutant microorganism producing succinic acid at a high concentration while producing little or no other organic acids in anaerobic conditions, which is obtained by disrupting a gene encoding lactate dehydrogenase (ldhA), a gene encoding phosphotransacetylase (pta), and a gene encoding acetate kinase (ackA), without disrupting a gene encoding pyruvate formate lyase (pfl), as well as a method for producing succinic acid using the same. The inventive mutant microorganism has the property of having a high growth rate and succinic acid productivity while producing little or no organic acids, as compared to the prior strains producing succinic acid. Thus, the inventive mutant microorganism is useful to produce succinic acid for industrial use.

Methods of enhancing the growth rate and / or controlling the metabolic activity of lactic acid bacteria and of improving the shelf life and / or the quality of an edible product using lactic acid bacterial organisms which are defective in their pyruvate metabolism. There is also provided starter culture compositions comprising such defective lactic acid bacteria as helper organisms and lactic acid bacterial starter culture strains. Useful helper organisms are Lactococcus strains which are defective with respect to pyruvate formate lyase (Pfl) and / or lactate dehydrogenase (Ldh) activity. The helper organisms may overexpress a gene coding for an NAD<+ >regenerating enzyme such as NADH oxidase encoded by nox gene.