Method for producing L-amino acid

Abstract

A bacterium belonging to the genus Escherichia which has an ability to produce an L-amino acid, wherein the ability to produce the L-amino acid is increased by increasing expression of an L-amino acid excretion protein is described. A method for producing the L-amino acid using the bacterium is also described.

1 . A method for producing an L-amino acid selected from the group consisting of L-glutamic acid, L-proline, and L-lysine comprising: 
 cultivating a bacterium in a culture medium,    and recovering the L-amino acid from the medium,    wherein said bacterium belongs to the genus  Escherichia  and wherein expression of at least one protein selected from the group consisting of:    (A) a protein having an amino acid sequence shown in SEQ ID NO: 10; and    (B) a protein which is encoded by a DNA which hybridizes with a polynucleotide having the nucleotide sequence shown in SEQ ID NO: 9 under stringent conditions comprising 60° C., 1×SSC, and 0.1% SDS, and which has an activity of producing L-proline, L-lysine, and L-glutamic acid,    is increased relative to the expression of said protein in a wild-type strain by increasing the copy number of a DNA coding for said protein in said bacterium or by replacing the native promoter with a stronger promoter.    
     
     
         2 . The method of  claim 1 , wherein the copy number of a DNA coding for said protein in a bacterium is increased.  
     
     
         3 . The method of  claim 2 , wherein said DNA is carried on a multicopy vector in the bacterium.  
     
     
         4 . The method of  claim 2 , wherein said DNA is carried on a transposon in the bacterium.  
     
     
         5 . The method of  claim 1 , wherein production of said protein of (A) is increased.  
     
     
         6 . The method of  claim 1 , wherein production of said protein of (B) is increased.  
     
     
         7 . The method of  claim 1 , wherein the L-amino acid is L-glutamic acid.  
     
     
         8 . The method of  claim 1 , wherein the L-amino acid is L-proline.  
     
     
         9 . A method for producing an L-amino acid selected from the group consisting of L-glutamic acid, L-proline, and L-lysine comprising 
 cultivating a bacterium in a culture medium,    and recovering the L-amino acid from the medium,    wherein said bacterium belongs to the genus  Escherichia  and wherein expression of at least one protein selected from the group consisting of:    (A) a protein having an amino acid sequence shown in SEQ ID NO: 10; and    (B) a protein which is encoded by a DNA which hybridizes with a polynucleotide having the nucleotide sequence shown in SEQ ID NO: 9 under stringent conditions comprising 60° C., 1×SSC, and 0.1% SDS, and which has at least an activity of producing an L-amino acid selected from the group consisting of L-glutamic acid, L-proline, and L-lysine,    is increased relative to the expression of said protein in a wild-type strain by increasing the copy number of a DNA coding for said protein in said bacterium or by replacing the native promoter with a stronger promoter.    
     
     
         10 . The method of  claim 9 , wherein the copy number of a DNA coding for said protein in a bacterium is increased.  
     
     
         11 . The method of  claim 10 , wherein said DNA is carried on a multicopy vector in the bacterium.  
     
     
         12 . The method of  claim 10 , wherein said DNA is carried on a transposon in the bacterium.  
     
     
         13 . The method of  claim 9 , wherein production of said protein of (A) is increased.  
     
     
         14 . The method of  claim 9 , wherein production of said protein of (B) is increased.  
     
     
         15 . The method of  claim 9 , wherein the L-amino acid is L-glutamic acid.  
     
     
         16 . The method of  claim 9 , wherein the L-amino acid is L-proline.