Induced variability of Streptomyces galbus

A-factor, a regulating substance is an obligatory participant of streptomycin biosynthesis by Str. griseus. Str. galbus also synthesizes streptomycin but without participation of A-factor. Mutant with various morphological properties were obtained under the effect of ethylenimine. No correlation between spore formation and streptomycin synthesis was found in the mutants of Str. galbus unlike Str. griseus. Correlation between a decrease in the capacity for production of a dark brown pigment and an increase in the level of streptomycin biosynthesis was shown: the mutants with the dark brown pigment did not synthesize streptomycin, while the mutants without the pigment synthesized streptomycin in the amounts 10-14 times higher than those in the initial strain. The same as the initial strain, the mutants of Str. galbus had no A-factor and did not respond to its addition into the medium by changing their properties and streptomycin synthesis.