Interrelationships between amino-acids in the growth of coliform organisms

SUMMARY: Three hundred and fifty-six strains of Bacterium coli, which were capable of growing on a simple salt medium containing ammonia as sole nitrogen source and glucose, were tested for inhibition of growth by added amino-acids. Inhibitions by certain amino-acids were found, and each inhibition could be prevented by the simultaneous presence of one or more other amino-acids. It was not possible to correlate these inhibitions with any other biochemical property of the strains. There was, however, a remarkably high proportion of serine-inhibited strains amongst those which had been isolated from cases of infantile gastro-enteritis. There are numerous reports in the literature concerning the inhibitory effects of naturally occurring amino-acids on the growth of various organisms under special conditions. A classic example is the study by Gladstone (1939) of the growth of several Bacillus anthracis strains in defined amino-acid media; when leucine or valine separately were added in concentrations as low as 1 pg./ml. growth did not occur; when both amino-acids were simultaneously present or were both absent the organisms grew well