Method of producing L-glutamic acid by fermentation

A method of producing L-glutamic acid by fermentation, comprising the steps of

• culturing a mutant of an L-glutamic acid-producing microorganism of the species Corynebacterium glutamicum which has an .alpha.-ketoglutaric acid dehydrogenase activity which is between 1/5 and 1/500 of that of the wild strain from which said mutant is derived, in a liquid culture medium comprising biotin at a concentration of at least 10 .mu.g/l in the absence of a biotin activity-suppressing substance selected from the group consisting of penicillin G, penicillin F, penicillin K, penicillin O, penicillin V, penicillin X, sucrose monopalmitate, and polyoxyethylene sorbitan monopalmitate;
• producing and accumulating L-glutamic acid in said culture medium in an amount greater than that produced by said wild strain;
• and
• recovering said L-glutamic acid from said culture medium;
• whereby the accumulation of L-glutamic acid is not inhibited by any concentration of biotin in the culture medium within he range of 10 to 1,000 .mu.g/l.