Patent ID: 7666634

Claim:
A fermentation process suitable for the preparation of a desired L-amino acid selected from the group consisting of L-threonine, L-isoleucine, L-valine, and L-lysine, wherein the following steps are carried out: a) fermentation of an E. coli strain in a fermentation broth for producing the desired L-amino acid, wherein the endogenous ytfP-yjfA gene region of E.coli is inactivated by one or more methods of mutagenesis selected from the group consisting of deletion, insertional mutagenesis due to homologous recombination, and transition or transversion mutagenesis with incorporation of a non-sense mutation in the ytfP-yjfA gene region, and b) concentration of the fermentation broth to eliminate water and increase the concentration of said L-amino acid, and c) isolation of the L-amino acid.