Formation of Glutamine by Combination of Bifidobacterial Sugar Fermentation and Bacterial Glutamine Synthetase

Abstract

Glutamine formation was observed by coupling the reaction of bacterial glutamine synthetase with the sugar fermentation system of Bifidobacterium pseudolongum c. About 5 mM glutamine was formed in 1 hr of incubation at 37°C with 15 mM glutamate, 15 mM NH₄Cl, 30 mM potassium phosphate buffer (pH 7.0), 10 mM glucose, 3.4 mg/ml toluol-treated B. pseudolongum c cells and 50 units/ml glutamine synthetase. The reaction proceeded in autoclaved swine feces without the addition of NH₄Cl. In the toluol-treated fresh feces of a breast-fed infant where bifidobacterial growth occurred preferentially, glutamine formation proceeded without the addition of bifidobacterial cells, NH₄Cl, or phosphate, however glutamate was necessary. Based on these results, ammonia detoxification in the intestine by bifidobacteria was discussed.