TEMPERATURE-SENSITIVE REPRESSION OF STAPHYLOCOCCAL PENICILLINASE.

In eight highly inducible strains of Staphylococcus aureus repression of the formation of penicillinase was temperature-sensitive under conditions suggesting direct thermal inactivation of the repressor. Restoration of repression required protein synthesis. These strains were resistant to benzylpenicillin and to many other antibiotics. One auxotrophic mutant had gredtly reduced temperature sensitivity but was still normally inducible. Six strains were relatively poorly inducible, exhibited a proportionately smaller increase in enzyme after exposure to elevated temperature, and were sensitive to antibiotics other than benzylpenicillin. Temperature sensitivity may be a useful character in studies of the physiology and genetics of the repression of staphylococcal penicillinase.