Immunological properties of exopenicillinase synthesized by Bacillus cereus 569/H in the presence of amino acid analogues

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Abstract
Addition of canavanine to cultures of Bacillus cereus growing exponentially in fully synthetic amino acid media, lacking arginine, leads to complete inhibition of growth and exopenicillinase formation after incubation for about 90 min. in the presence of the analogue. The differential rate of exopenicillinase formation is, however, markedly inhibited before growth ceases completely. Addition of p-f luorophenylalanine to cultures growing exponentially in a fully synthetic medium lacking phenylalanine leads to impaired growth which nevertheless continues in an approximately linear manner for 4-5 hr. During this period the differential rate of exopenicillinase synthesis is increasingly inhibited, falling to about half normal after 90 min. incubation in the presence of the analogue. Comparison of the immunological neutralization of exopenicillinase formed in the presence of canavanine or p-fluorophenylalanine with normal exopenicillinase suggests that the abnormal enzyme preparations may have impaired specific enzyme activity and lowered efficiency of reaction with specific anti-exopenicillinase serum. The appearance of the abnormal material may be induced in the inducible (569) strain of B. cereus under the conditions necessary for induction of penicillinase in normal cultures. The immunological "abnormality" of exopenicillinase preparations obtained from cultures increases as incubation in the presence of the amino acid analogues is prolonged.