Detection and Study of Cosynthesis of Tetracycline Antibiotics by an Agar Method

Abstract

SUMMARY: Pairs of non-tetracycline-producing mutants of Streptomyces rimosus or S. aureofaciens were grown side by side on agar. Their ability to produce antibiotic by cosynthesis was tested by placing a strip of agar cut from the combined culture on plates containing Bacillus subtilis. The activity was revealed as an inhibition halo formed on B. subtilis, opposite one or other mutant strain. The strain surrounded by the halo was considered as a converter of an intermediate product secreted by the other strain. Two types of mutants were observed: a rare type probably affecting the main pathway of antibiotic biosynthesis, and a more frequent type probably affecting some regulatory process.