L-Amino Acid-Producing Bacterium and Method for Producing L-Amino Acid

Abstract

An L-amino acid is produced by culturing a Methylophilus bacterium which can grow by using methanol as the main carbon source and has L-amino acid-producing ability, for example, a Methylophilus bacterium in which dihydrodipicolinate synthase activity and aspartokinase activity are enhanced by transformation of cells with a DNA coding for dihydrodipicolinate synthase that is desensitized to feedback inhibition by L-lysine and a DNA coding for aspartokinase that is desensitized to feedback inhibition by L-lysine, or a Methylophilus bacterium which is casamino acid auxotrophic, in a medium containing methanol as a main carbon source, to produce and accumulate an L-amino acid in culture, and collecting the L-amino acid from the culture.

What is claimed is: 
     
         1 . A method for producing L-lysine comprising culturing a  Methylophilus  bacterium in a medium containing methanol to produce and accumulate L-lysine in the medium, and collecting L-lysine from the medium, wherein said  Methylophilus  bacterium has been modified to have enhanced activities of dihydrodipicolinate synthase and aspartokinase by transformation with a DNA from  Escherichia coli  that encodes dihydrodipicolinate synthase resistant to feedback inhibition by L-lysine and with a DNA from  Escherichia coli  that encodes aspartokinase resistant to feedback inhibition by L-lysine. 
     
     
         2 . The method according to  claim 1 , wherein said DNA from  Escherichia coli  that encodes dihydrodipicolinate synthase encodes dihydrodipicolinate synthase comprising replacement of histidine at position 118 in SEQ ID NO: 2 with tyrosine. 
     
     
         3 . The method according to  claim 1 , wherein said DNA from  Escherichia coli  that encodes aspartokinase encodes aspartokinase comprising replacement of threonine at position 352 in SEQ ID NO: 4 with isoleucine.