METABOLIC CONTROL OF PENICILLINASE BIOSYNTHESIS IN BACILLUS CEREUS.

Yip, Lily C. (University of Cincinnati, Cincinnati, Ohio), Ramesh Shah, and Richard A. Day. Metabolic control of penicillinase biosynthesis in Bacillus cereus. J. Bacteriol. 88:297-308. 1964.-Penicillinase production in strains 5 and 5/B of Bacillus cereus in response to treatment by 6-aminopenicillanic acid (APA), penicillin G, (6-N-alpha-(p-benzyloxyphenoxy)-propionylamino-penicillanic acid, and cephalosporin C (CC) was found to be analogous to that seen in constitutive strains. Strain 5 did not release penicillinase into the medium to any great extent. Penicillinase production and the effect of the above penicillins on it were found to decline with increasing density of the culture. The penicillins were shown to accelerate or retard the production of penicillinase activity in strain 5 cells during pretreatment at 0 C and during incubation at 37 C. Strains 5 and 5/B gave qualitatively similar responses to penicillin treatment. At 0 C, the specific activity of penicillinase in strain 5 passes through a period of rapid increase at 0 hr and a period of little change at approximately 1 hr, followed by an increased rate of change towards 2 hr. The effect of APA or CC on specific activity of strain 5 cells during treatment at 0 C could not be reversed by one another, but Hg could reverse the increase caused by CC to some extent and the repression caused by APA. The production of penicillinase in the microconstitutive strain 5 of Bacillus cereus in response to treatment with CC was influenced by various inhibitors. 8-Azaguanine inhibited the production of the enzyme both during a pretreatment of the cells with CC at 0 C and during the subsequent incubation at 37 C. Actinomycin D, 6-azauracil, 6-thioguanine, and 2-thiocytosine inhibit the increase in penicillinase arising after the pretreatment at 0 C. 6-Azathymine has very little effect on the change of penicillinase activity. The CC-induced change occurring during the 0 C period was postulated to be a process at the level of protein biosynthesis itself; change at 37 C, constituting a delayed response, was considered a process at the level of messenger ribonucleic acid synthesis.