[Mutagenic effect of mitomycin C on different strains of oleandomycin producer Streptomyces antibioticus].

Mitomycin C, a DNA-tropic antibiotic, was shown to have a lethal effect on spore sprouts of two strains of Streptomyces antibioticus, an organism producing oleandomycin. When the time of exposure to the antibiotic increased there was an almost equal decrease in the survival rate. The mutagen action on the morphological variation and antibiotic production of the two closely related strains were diverse due to their genetic differences.

[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.

[Intergeneric hydridization of the actinomycetes Streptoverticillium mycoheptinicum and Streptomyces coelicolor].

Intergeneric crossing of the actinomycetes Streptoverticillium mycoheptinicum and Streptomyces coelicolor yielded recombinants which were mostly nonviable and unstable despite a relatively high frequency (10(-2)-10(-4)) at which their colonies appeared. The rare viable and stable recombinants were prototrophs. The structure of antibiotics in the hybrid cell may be modified as follows from the differences in the antibiotic activity of the LIA-973 hybrid and the parent strains.

[Auxotrophic mutants of the producer of the antibiotic mycoheptin Streptoverticillium mycoheptinicum].

The lethal and mutagenic effects of N-nitrozo-N-methyl biuret (NMB), N-nitrozo-N-methyl urea (NMU) and UV light on Streptoverticillium mycoheptinicum, strains O883 and 852, were studied. The concentrations of NMB were 0.005, 0.