L-amino acid-producing bacterium and a method for producing an L-amino acid

摘要

A bacterium belonging to the family Enterobacteriaceae, which has an ability to produce an amino acid such as L-cysteine and has been modified to have specific mutation in the yeas gene, is cultured in a medium, and the L-amino acid is collected from the medium.

主权项

1. A method for producing an L-amino acid comprising:
a) culturing in a medium a bacterium belonging to the family Enterobacteriaceae, which is able to produce an L-amino acid, and has been modified to have a mutation in a yeaS gene selected from the group consisting of:
(I) replacing the amino acid residue at position 28 of SEQ ID NO: 2 with an amino acid residue other than threonine,(II) replacing the amino acid residue at position 137 of SEQ ID NO: 2 with an amino acid residue other than phenylalanine residue,(III) replacing the amino acid residue at position 188 of SEQ ID NO: 2 with an amino acid residue other than leucine, and,(IV) combinations thereof; and b) collecting the L-amino acid from the medium; wherein the yeaS gene without said mutation encodes a protein selected from the group consisting of: (A) a protein comprising the amino acid sequence of SEQ ID NO: 2, and (B) a protein comprising the amino acid sequence of SEQ ID NO: 2, but wherein 1 to 10 amino acid residues are substituted, and the protein has an activity of improving an L-cysteine-producing ability in the bacterium belonging to the family Enterobacteriaceae as compared to a non-modified bacterium when expression of the protein is increased in the bacterium.