Patent ID: 6344347
Filing Date: 2002-02-05
Classification: C12N,C12P,C12R,Y10S

Abstract:
A method for producing L-histidine, which comprises:(a) subjecting a microorganism belonging to the genus Escherichia and having an ability to produce an L-amino acid as a parent strain to a mutation treatment selected from ultraviolet irradiation and treatment with mutagen to obtain mutant strains; (b) culturing the resulting mutant strains on an agar plate medium containing a DNA gyrase inhibitor at a concentration at which the parent strain cannot grow or at which the parent strain grows poorly and whereby mutant strains that have a resistance to the gyrase inhibitor produce colonies that grow more rapidly than the parent strain or colonies that are larger than that of the parent strain; (c) selecting colonies that grow more rapidly than the parent strain or colonies that are larger than that of the parent strain from among colonies on the agar plate medium to obtain a microorganism belonging to the genus Escherichia having an ability to produce L-histidine and having resistance to a DNA gyrase inhibitor; (d) culturing in a culture medium said microorganism; (e) producing and accumulating L-histidine in the culture medium; and (f) recovering L-histidine from the culture medium.