[Toxic action of the polyene antibiotic levorin on the superproducer Streptomyces levoris].

Along with an increase in the activity of a superproductive strain of Str. levoris there was observed in its population an increase in the number of low active cells sensitive to high concentrations of the own antibiotic. Levorin had an especially high toxic action on viability and antibiotic activity of the low productive strain 78/19 as compared to the highly productive strain 78/72. Resistance of the levorin-producing organism to its own antibiotic was associated with composition and properties of the cytoplasmic membrane. Acridine orange had no effect on survival and morphological variation of the strains studied. It had either no effect on the antibiotic production by the low active strain 78/19. However, under the effect of the dye there was induced marked variation in the highly productive strain 78/72 with respect to the antibiotic production property: decreasing of the population activity due to elimination of highly productive variants and accumulation of low productive variants. The data suggested the presence of plasmid genes in the levorin-producing organism determining biosynthesis of the antibiotic and resistance to it.