Mode of Action of Pesticin

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Abstract
The mode of action of pesticin, a bacteriocin produced by many strains ofPasturella pestis, was studied. Pesticin action on macromolecular synthesis of a sensitive strain ofEscherichia coli, strain φ, was found to have features similar to those of colicin E2-317 acting on the same strain. After exposure to pesticin, deoxyribonucleic acid synthesis was arrested and ribonucleic acid was degraded, but little effect was observed on protein synthesis. Pesticin, like colicin E2-317, induced lysogenicE. coliφ (P1), but, unlike the colicin, was active in the presence of dinitrophenol. Trypsin was found to reverse pesticin action up to 15 min after its addition at 40 C toE. coliφ. Pesticin action was studied on three sensitive bacterial strains,P. pestis2C,P. pseudotuberculosis, andE. colistrain φ, which vary widely in their optimal growth temperature.P. pestisgrows best at 29 C,P. pseudotuberculosisat 37 C, andE. coliφ at 40 C. It was found that pesticin action on all three strains was optimal at 40 C. Whereas the titer of pesticin was the same on all three strains when determined on agar,E. coliφ was the most sensitive to pesticin action in broth. No action of pesticin in broth onP. pseudotuberculosiswas observed unless Ca ions were added. The effect was not immediate; that is, the cells had to be grown in a medium containing Ca++before they displayed sensitivity to pesticin.

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