Production of l -Glutamine by a Penicillin-Resistant Mutant of Flavobacterium rigense

Abstract

To establish a practical method for the fermentative production of l -glutamine, cultural conditions for the accumulation of a large amounts of l -glutamine were investigated by using Flavobacterium rigense 703, which was previously reported by us as a l -glutamine-producing mutant. As a result, a yield of 25 mg of l -glutamine per ml was obtained after a 48-h cultivation in a medium containing glucose, yeast extract, (NH 4 ) 2 -fumarate, KH 2 PO 4 , K 2 HPO 4 , MgSO 4 .7H 2 O, and CaCO 3 (pH 6.4). Accumulation of l -glutamine was dependent upon the concentration of (NH 4 ) 2 -fumarate, and a suboptimum growth at a relatively high concentration of (NH 4 ) 2 -fumarate was essential for the maximum production of l -glutamine. At the optimum conditions, glutamic acid was formed as a by-product at a concentration of less than 1 mg/ml, but accumulation of the other amino acids was negligible. The product was isolated from the culture broth and readily purified by anion-exchange chromatography. The pure crystals of l -glutamine obtained in an 80% yield were optically and chromatographically pure.

Mechanism of l -Glutamine Production by an l -Glutamine-Producing Mutant of Flavobacterium rigense

“…As described in previous papers (6,7), we found that a penicillin-resistant mutant of Flavobacterium rigense, strain 703, produces 25 g of L-glutamine per liter in a culture medium containing mainly 5% glucose and 7% (NH4)2fumarate. The existence of 0.9 to 1.6% ammonia and 5.5% fumaric acid in a medium is essential for the accumulation of large amounts of L-glutamine.…”

“…3556) (17) were used. The conditions for stock culture were described previously (6). L-Glutamine production medium (basal medium) contained 5% glucose, 1.5% yeast extract, 7% (NH4)2-fumarate, 0.1% KH2PO4, 0.1% K2HPO4, 0.05% MgSO4.…”

“…Cultivation was carried out in a 500-ml flask containing 50 ml of medium for 48 h at 30°C on a reciprocal shaker operating at 140 strokes per min with a 7-cm amplitude. Cell growth was determined as described previously (6).…”

“…Analytical methods. Unless otherwise stated, analytical methods were the same as described previously (6,7).…”

Characteristics and Efficiency of Glutamine Production by Coupling of a Bacterial Glutamine Synthetase Reaction with the Alcoholic Fermentation System of Baker’s Yeast

“…Glutamine is one of the most important compounds in nitrogen metabolism; it is not only a constituent of proteins but is also a donor of the amino (amido) moiety in the biosynthesis of other amino acids, purines, pyrimidines, pyridine coenzymes, and complex carbohydrates. Glutamine is also used in the treatment of gastric ulcers and has been produced commercially by direct fermentation with certain bacteria (6)(7)(8)(9)(10).…”