Influence of nitrogen source and growth status on glutamine synthetase and glutamate synthase activity in...

An investigation was made of the activity of glutamine synthetase and glutamate synthase from batch-cultured cells of Mycobacterium avium. The bacteria were grown in medium with ammonium chloride concentrations of 0, 0.1, 0.25, 1, 5, or 25 mumol/mL or with glutamine at 0.1 or 1 mumol/mL. The specific activity of the two enzymes was determined at 0, 22, 45, and 70 h of incubation. Regardless of the ammonia concentration in the medium, glutamate synthase specific activity was two to five times higher in extracts from elongating cells, incubated 22 h, than in those from shortened cells, incubated 45 or 70 h. In contrast, there was no apparent difference in glutamine synthetase specific activity with regard to culture age; however, glutamine synthetase specific activity varied inversely with the concentration of ammonium chloride in the medium. Cells grown in glutamine had high activity of glutamine synthetase.