Glutamine synthetase and glutamate synthase activities during growth and sporulation in Bacillus subtilis.

Glutamine synthetase in Bacillus subtilis 168 was repressed to a greater extent by L-glutamine or L-arginine than by ammonia when each was used as sole nitrogen source. It was derepressed when either L-glutamate or nitrate was used as nitrogen source. Glutamate synthase was repressed by L-glutamate or L-arginine and, to a lesser extent, by L-glutamine but was derepressed during growth with ammonia or nitrate. Glutamine synthetase activity was unaltered during the onset of sporulation. Glutamate synthase activity, however, underwent a small and apparently transient increase in bacteria induced to sporulate by nitrogen limitation.