Method for producing L-amino acids
The invention is directed to a process for producing an L-amino acid by fermenting a microorganism, wherein the expression of a lysC gene encoding a feed back resistant aspartokinase is enhanced by cloning a strong promoter/ribosome binding sequence.
1 . An isolated microorganism comprising within its genome a nucleotide sequence encoding a feedback resistant aspartokinase enzyme, operably linked to a sequence selected from the group consisting of SEQ ID NO:1 -SEQ ID NO:20.
2 . The isolated microorganism of claim 1 , wherein said feedback resistant aspartokinase enzyme comprises the amino acid sequence of SEQ ID NO:22 except that a proteinogenic L-amino acid other than L-serine is present at position 301.
3 . The isolated microorganism of claim 1 , wherein said microorganism is produced by homologous recombination.
4 . The isolated microorganism of claim 2 , wherein said microorganism is a coryneform bacterium.
5 . The isolated microorganism of claim 4 , wherein said coryneform bacterium is C. glutamicum.
6 . A process for the fermentative production of an L-amino acid comprising:
a) culturing the coryneform bacterium of claim 1 in a fermentation medium;
b) allowing said fermentation medium or said coryneform bacterium to become enriched in said L-amino acid; and
c) isolating said L-amino acid.
7 . The process of claim 6 , wherein some or all of the constituents of said fermentation medium and/or the biomass of said coryneform bacterium are isolated with said L-amino acid.
8 . The process of claim 6 , wherein said L-amino acid is selected from the group consisting of L-lysine, L-methionine and L-serine.
9 . The process of claim 6 , wherein said L-amino acid is L-lysine.
10 . The process of claim 9 , wherein said coryneform bacterium is C. glutamicum.