Method for fermentative production of amino acids and amino acid derivatives of the phosphoglycerate family
A microorganism strain suitable for fermentative production of amino acids of the phosphoglycerate family or derivatives thereof and producible from a starting strain, is based upon a starting strain having an increased activity of a yfiK-gene product or of a gene product of a yfiK homologue. The microorganism strain is a member of the family Enterobacteriaceae and is a member of the species E. coli. A plasmid has a Yfik-gene with a promoter and a genetic element for the deregulation of cysteine metabolism coding for a serine O-acetyl transferase and being subject tot a reduced feedback inhibition by L-cysteine.
1 . A method for preparing an amino acid selected from the group consisting of O-acetyl-L-serine, N-acetyl-L-serine, L-cysteine, and LL-cystine, which comprises using a microorganism strain having an increased cellular activity of the Yfik-gene product or of a gene product of a Yfik-homologue having more than 30% Aa sequence identity to SEQ ID NO: 2 in a fermentation mixture; and removing the amino acid produced from the fermentation mixture.
2 . The method as claimed in claim 1 , wherein the microorganism strain is grown in a fermenter as a culture selected from the group consisting of a continuous culture, a batch culture, and a fed-batch culture.
3 . The method as claimed in claim 1 , wherein a carbon source is continuously-metered in during fermentation.
4 . The method as claimed in claim 3 , wherein the carbon source used is selected from the group consisting of a sugar, a sugar alcohol and an organic acid.
5 . The method as claimed in claim 1 , wherein the carbon source is metered in, in a way so as to ensure that a content of the carbon source in a fermenter is kept in a range from 0.1-50 g/l, during fermentation.
6 . The method as claimed in claim 5 , wherein the carbon source in the fermenter is kept in a range from 0.5-10 g/l, during fermentation.
7 . The method as claimed in claim 1 , wherein a nitrogen source is used and is selected from the group consisting of ammonia, an ammonium salt and a protein hydrolysate.
8 . The method as claimed in claim 1 , wherein fermentation is carried out under aerobic growth conditions.