EFFECT OF SOME ANTIMETABOLITES ON THE PRODUCTION OF STREPTOLYSIN S

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Abstract
The production of streptolysin S[image] by resting cells of Streptococcus pyogenes, strain C203S, was studied. Below 0.05 mg/ml of active fraction (AF), the maximum yield of hemolysin was dependent upon the concentration of AF. Among 10 amino acid analogues tested, [image]-DL-phenylserine was the most potent inhibitor. Fifty per cent inhibition was obtained by IX 10-3 [image] of the antagonist which could be completely reversed by DL-phenylalanine. Benzimidazole caused 84% inhibition at 1 X 10-2 [image]. Freshly harvested cells contained about 1.5% (dry weight) of endogenous amino acid pool which was partially depleted by incubation in a nitrogen-free medium. The AF did not appreciably enhance the overall uptake of the intracellular amino acids. Under optimum conditions of the production of streptolysin S[image], the ratio of the yields of extracellular to intracellular hemolysin was 70:1. The effect of streptomycin, chloramphenicol, Aureomycin, Terramycin and tetracycline was tested. The last 3 antibiotics were extremely potent inhibitors. Penicillin-G and azaserine were inactive. These data support Bernheimer''s view that the appearance of hemolytic activity in the suspension medium of resting cocci involves a synthetic process.