Bacterium having enhanced 2-oxoglutarate dehydrogenase activity
View Patent ↗Provided is a bacterium which is capable of producing an organic acid and is modified so as to have an enhanced 2-oxoglutarate dehydrogenase activity as compared with that of an unmodified strain. An organic acid such as succinic acid can be produced by culturing the bacterium.
1. A coryneform bacterium having succinic acid-producing ability, wherein said bacterium is modified so that 2-oxoglutarate dehydrogenase activity is enhanced as compared with the corresponding unmodified bacterium by placing a gene encoding 2-oxoglutarate dehydrogenase under the control of a strong heterologous promoter or by increasing the copy number of said gene,
wherein said gene encoding 2-oxoglutarate dehydrogenase has a nucleotide sequence not less than 95% homologous to SEQ ID NO: 3, and
wherein the bacterium is further modified so that lactate dehydrogenase activity is decreased by introducing a deletion or insertion in a gene encoding lactate dehydrogenase, and pyruvate carboxylase activity is enhanced by placing a gene encoding pyruvate carboxylase under the control of a strong heterologous promoter or by increasing the copy number of said gene.
2. A coryneform bacterium having succinic acid-producing ability, wherein said bacterium is modified so that acetic acid production is decreased by decreasing
(a) one of or both of acetate kinase activity and phosphotransacetylase activity,
(b) acetyl-CoA hydrolase activity, and
(c) pyruvate oxidase activity,
by introducing a deletion or insertion in a gene encoding each enzyme, and 2-oxoglutarate dehydrogenase activity is enhanced as compared with the corresponding unmodified bacterium by placing a gene encoding 2-oxoglutarate dehydrogenase under the control of a strong heterologous promoter or by increasing the copy number of said gene, and
wherein said gene encoding 2-oxoglutarate dehydrogenase has a nucleotide sequence not less than 95% homologous to SEQ ID NO: 3, and
wherein the bacterium is further modified so that lactate dehydrogenase activity is decreased by introducing a deletion or insertion in a gene encoding lactate dehydrogenase.
3. The coryneform bacterium according to claim 2 , wherein the bacterium is further modified so that pyruvate carboxylase activity is enhanced by placing a gene encoding pyruvate carboxylase under the control of a strong heterologous promoter or by increasing the copy number of said gene.
4. A method for producing succinic acid, comprising:
allowing the coryneform bacterium according to any one of claims 1 , 2 and 3 or a treated cell thereof to act on an organic raw material under anaerobic atmosphere in a reaction solution containing a carbonate ion, a bicarbonate ion, or carbon dioxide gas to thereby produce succinic acid; and
collecting the succinic acid.
5. The method according to claim 4 , wherein the organic raw material is glucose or sucrose.
6. A method for producing a succinic acid-containing polymer, comprising:
producing succinic acid by the method according to claim 4 ; and
subjecting the obtained succinic acid as a raw material to a polymerization reaction.