EDEMA FACTOR AND PHOSPHOLIPASE RELEASE BY A STRAIN OF BACILLUS CEREUS

After ultraviolet light irradiation, strain 6464 of Bacillus cereus lysed, resulting in the release of toxin, phospholipase, and mature phage particles. Small amounts of toxin and phospholipase produced by non-induced cultures were correlated with the infrequent spontaneous release of bacteriophage. Stationary incubation following ultraviolet induction results in a greater yield of toxin and phospholipase than post irradiation incubation on a shaker. Postirradiation incubation at temperatures below 37° either reduced (30°) or prevented (26°) toxin and phospholipase production. A clone was obtained which was sensitive to the phage from the parent strain and was presumably no longer lysogenic for it. This cured strain still exhibited ultraviolet-induced optical density decline accompanied by release of toxin and phospholipase. Mitomycin C would induce strain 6464 and the cured strain derived from it and both released toxin and phospholipase during mitomycin C induced lysis. The induced lysis of the cured strain could be prevented by postinduction treatment with inhibitors of synthesis of protein (chloramphenicol), RNA (actinomycin D), or DNA (5-fluorouracil deoxyriboside).