[Formation of A-factor-type regulators by representatives of the genus Micromonospora].

It is known that substances similar in their chemical structure and biological action to A-factor, a regulator of Streptomyces griseus differentiation are widely observed in streptomycetes. The present paper is concerned with studies on capacity for producing A-factor-like regulators in 13 strains belonging to 11 species of genus Micromonospora. It was shown that 7 strains had an A-factor-deficient test mutant effect analogous to the effect of A-factor. Relation of A-factor-like substance production to biosynthesis of sisomicin and sporogenesis was investigated in M. fusca var. sisomicini, strain RIA 1572. A-Factor-like substances were isolated from submersion culture of strain 1572 on the 6th-8th day of the culture growth. By the time it corresponded to the highest number of the spores in the medium. The highest levels of sisomicin were detected on the 3rd day of the fermentation process. After that period its concentration markedly lowered. Exogenic addition of A-factor had no effect on sisomicin biosynthesis but resulted in increased numbers of the spores.