Patent ID: 6916637

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, the process comprising: a) fermentation of an E. coli strain in a fermentation broth for producing the desired L-amino acid, wherein the endogenous gene encoding phosphoenolpyruvate (PEP) carboxykinase (pckA gene) 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 pckA gene, and b) elimination of water from the fermentation broth to increase the concentration of said L-amino acids; and c) isolation of the L-amino acids.