Method for producing an acidic substance having a carboxyl group

Abstract

An acidic substance having a carboxyl group is produced by culturing in a medium a microorganism which has been modified to enhance expression of the ybjL gene, and collecting the acidic substance having a carboxyl group from the medium.

1 . A microorganism that has an ability to produce an acidic substance having a carboxyl group and has been modified to enhance expression of the ybjL gene. 
     
     
         2 . The microorganism according to  claim 1 , wherein said enhanced expression is obtained by a method selected from the group consisting of: A) increasing copy number of the ybjL gene, B) modifying an expression control sequence of the ybjL gene, and C) combinations thereof. 
     
     
         3 . The microorganism according to  claim 1 , wherein the ybjL gene encodes a protein selected from the group consisting of:
 (A) a protein comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 2, 4, and 87;   (B) a protein comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 2, 4, and 87, but wherein one or several amino acid residues are substituted, deleted, inserted or added, and the protein improves the ability of the microorganism to produce an acidic substance having a carboxyl group when expression of the gene encoding the protein is enhanced in the microorganism.   
     
     
         4 . The microorganism according to  claim 1 , wherein the ybjL gene encodes for a protein selected from the group consisting of SEQ ID NO: 5 and 88. 
     
     
         5 . The microorganism according to  claim 1 , wherein the microorganism is a bacterium belonging to the family Enterobacteriaceae. 
     
     
         6 . The microorganism according to  claim 5 , wherein the bacterium belongs to a genus selected from the group consisting of  Escherichia, Enterobacter, Raoultella, Pantoea , and  Klebsiella.    
     
     
         7 . The microorganism according to  claim 1 , wherein the microorganism is a rumen bacterium. 
     
     
         8 . The microorganism according to  claim 7 , wherein the microorganism is  Mannheimia succiniciproducens.    
     
     
         9 . The microorganism according to  claim 1 , wherein the acidic substance is an organic acid selected from the group consisting of succinic acid, fumaric acid, malic acid, oxalacetic acid, citric acid, isocitric acid, α-ketoglutaric acid, and combinations thereof. 
     
     
         10 . The microorganism according to  claim 1 , wherein the acidic substance is L-glutamic acid and/or L-aspartic acid. 
     
     
         11 . A method for producing an acidic substance having a carboxyl group comprising culturing the microorganism according to  claim 1  in a medium to produce and accumulate the acidic substance having a carboxyl group in the medium, and collecting the acidic substance having a carboxyl group from the medium. 
     
     
         12 . The method according to  claim 11 , wherein the acidic substance is an organic acid selected from the group consisting of succinic acid, fumaric acid, malic acid, oxalacetic acid, citric acid, isocitric acid, α-ketoglutaric acid, and combinations thereof. 
     
     
         13 . The method according to  claim 11 , wherein the acidic substance is L-glutamic acid and/or L-aspartic acid. 
     
     
         14 . A method for producing an acidic substance having a carboxyl group comprising:
 A) allowing a substance to act on an organic raw material in a reaction mixture containing carbonate ions, bicarbonate ions, or carbon dioxide gas, wherein said substance is selected from the group consisting of:
 i) the microorganism according to  claim 1 , 
 ii) a product obtained by processing the microorganism of i), and 
 iii) combinations thereof, and 
   B) collecting the acidic substance having a carboxyl group.   
     
     
         15 . The method according to  claim 14 , wherein the acidic substance is an organic acid selected from the group consisting of succinic acid, fumaric acid, malic acid, oxalacetic acid, citric acid, isocitric acid, α-ketoglutaric acid, and combinations thereof. 
     
     
         16 . A method for producing a polymer comprising succinic acid, comprising:
 A) producing succinic acid by the method according to  claim 12 , and   B) polymerizing the obtained succinic acid.