Pesticins. I. Pesticinbacterium interrelationships, and environmental factors influencing activity.

Brubaker, Robert R. (U. S. Army Biological Laboratories, Fort Detrick, Frederick, Md.) and Michael J. Surgalla. Pesticins. I. Pesticin-bacterium interrelationships, and environmental factors influencing activity. J. Bacteriol. 82: 940-949. 1961-A second bacteriocin-like substance produced by all tested strains of Pasteurella pestis and P. pseudotuberculosis is described. This activity, termed pesticin II, is active against the two avirulent P. pestis strains, A12 and Java. These strains do not produce pesticin I, which inhibits the growth of type I strains of P. pseudotuberculosis. Pesticin I was also found to be active against certain strains of Escherichia coli, strain A12, but not strain Java, and some P. pestis isolates which also produce pesticin I. A number of E. coli strains produce a substance which also inhibits the growth of strains A12 and Java; the activity of this substance is dependent upon the presence of high concentrations of Ca(++). The activity of both pesticins is inhibited under anaerobic conditions or in the presence of antiserum. The activity of pesticin I, but not pesticin II, is suppressed by Fe(+++), hemin, certain hemin-containing proteins, Mg(++), and inorganic phosphate. Suppression of pesticin I activity by Fe(+++) can be reversed by the addition of either Ca(++) or Sr(++) or by metal chelating agents. All tested strains of P. pestis and P. pseudotuberculosis produce a metabolite which suppresses the activity of pesticin I. The activity of this substance, termed pesticin I inhibitor, is enhanced by Fe(+++), and to a lesser extent by Mg(++) or by inorganic phosphate; its activity is suppressed by Mn(++) and by protamine sulfate.