GB954552A - Production of l (+)-glutamic acid - Google Patents

Abstract

L(+)-glutamic acid is prepared by aqueous aerobic fermentation of a nutrient medium containing sources of carbon and nitrogen, with a biotin-requiring, glutamic acid producing microorganism, the medium containing biotin in excess of the amount required for optimum production of the glutamic acid, an inhibitor being added to the fermenting medium subsequent to inoculation of the medium with the micro-organism, the inhibitor and the amount of it being such as to decrease, as fermentation proceeds, the intracellular L(+)-glutamic acid to a level less than half of that of a fermentation carried out without inhibitor and to increase the ratio of extracellular to intracellular L(+) glutamic acid to a value greater than 50, the amount of biotin, however, not being greater than 1 gram per litre of liquid medium. The inhibitor may be an antibiotic e.g., a penicillin, including Penicillin G, a -phenoxyethyl penicillin and a -phenoxymethyl penicillin which penicillins may be used in the form of a procaine, dibenzyl ethylenediamine, calcium, sodium, potassium or other salt thereof, cephalosporin C, oxamycin, novobiocin, tetracycline, oxytetracycline, chlortetracycline, streptomycin, dihydrostreptomycin sulphate, bacitracin, chloramphenicol and neomycin sulphate; phenol, resorcinol, sodium propionate and cetyl trimethyl ammonium bromide. The inhibitor is preferably added when the micro-organism has grown to the extent that would occur in the presence of about 1 to 5.0 parts of biotin per thousand million of medium. The amount of penicillin inhibitor is suitably 0.05-10 units per mol. of broth. The micro-organism may be a suitable strain of Bacillus subtilis, Escherichia coli, Micrococcus glutamicus, Bacillus-megaterium-Bacillus cereus intermediate type, Brevibacterium divaricatum, Brevibacterium aminagenes, Arthrobacter globiforme, Bacillus megaterium, Brevibacterium alanicum and Brevibacterium lactofermentus. The nutrient medium may comprise for example 20-37.5 parts of biotin per thousand million parts of broth. The carbon source may be dextrose, dextrin, beet molasses, cane molasses, corn syrup, black-strap molasses or hi-test molasses, some of which also provide the excess of biotin. The nitrogen source may be urea, ammonia, an ammonium salt or corn-steep liquor. The nutrient medium usually also comprises phosphates, sulphates, and magnesium, manganese, potassium and, may be, iron salts. The fermentation is preferably effected at a pH of 6.0 to 8.5, suitably accomplished by addition of urea, ammonia or an alkali metal hydroxide. Examples are given wherein Micrococcus glutamicus is used as micro-organism with excess of biotin and various of the above mentioned inhibitors or, comparatively in the absence of an inhibitor, or with inhibitor and biotin not in excess. Specifications 788,335, 826,097, 839,597, 844,910 and 849,280 are referred to.