[Streptonigron--a minor component of bruneomycin complex]. / Streptonigron--minornyi komponent bruneomitsinovogo kompleksa.

A mutant strain of the bruneomycin-producing culture which produced up to 10% of the minor component was selected. The component was identified as streptonigrone. It was isolated and its physicochemical properties and antibacterial activity were investigated. Trimethylsilyl derivatives of streptonigrone and bruneomycin were prepared. Their PMR spectra and electron impulse mass spectra were studied. Streptonigrone was shown to have antibacterial and cytotoxic activities which was 1 to 2 orders of magnitude lower than that of bruneomycin.

[Mutagenesis in Streptomycete cultures exposed to bleomycin]. / Mutagenez v kul'turakh streptomitsetov pri deistvii bleomitsina.

Mutagenic properties of bleomycin, an antitumor antibiotic were studied with respect to 2 species of streptomycetes producing practically important antibiotics. A multifold increase in the frequency of prototrophic revertants among the survivors of strains His- and Met- of Actinomadura carminata exposed to bleomycin was observed. Bleomycin was effective in induction of various morphological mutants, and auxotrophs at a high survival rate of the spores of Str. cremeus var. tobramycini, a tobramycin-producing organism. It was shown with the method of subsequent mutagenesis that the efficacy of induction of morphological and auxotrophic mutants in germinating spores of Actinomadura carminata, a carminomycin-producing organism by bleomycin in a concentration of 100 micrograms/ml and an exposure time of 5 minutes was much higher that in the latent spores. The mutagenic effect of bleomycin is comparable with that of ionizing radiation.

[Action of acridine dyes on antibiotic, pigment and aerial mycelium formation in streptomycete producers of multicomponent antibiotics]. / Deistvie akridinovykh krasitelei na obrazovanie antibiotika, pigmenta i vozdushnogo mitseliia u streptomitsetov--prudutsentov mnogokomponentnykh antibiotikov.

The ability of 5 streptomycetous species synthesizing multicomponent antibiotic to produce the antibiotic and water-soluble pigment and to form the aerial mycelium in the presence of acridine dyes was studied. It was found that the character of the produced complex changed, when acridine dyes were added to the medium under conditions not affecting the culture growth and the temperature was elevated. Colonies deficient with respect to formation of the aerial mycelium and with changed pigment and antibiotic production were detected in the monospore cultures of the streptomycetes treated with acridine dyes, when the spore survival was equal to 100 percent, the frequency of the colonies being about 40 per cent.

Auxotrophic mutants in the selection of the rubomycin producer, Actinomyces coeruleorubidus. / Auksotropnye mutanty v selektsii produtsenta rubomitsina----Actinomyces coeruleorubidus.

A total of 351 auxotrophic mutants with different antibiotic activity, including several mutants with activity higher than that of the parent prototrophic strains were obtained under the effect of gamma-rays from 3 prototrophic strains of Act. coeruleorubidus. It was shown that most of the auxotrophic mutants did not preserve the property of biochemical insufficiency on passages on complete media. A mutant strain 1059-32 with activity 2 times higher than that of the prototrophic strain 2-39 and the parent auxotrophic culture was obtained from the revertants. Requirements in 29 growth factors including 17 amino acids, 4 nitrous bases, 8 vitamins and coenzymes were determined in 46 stable auxotrophic mutants isolated. The effect of the specific and non-specific growth factors on the culture antibiotic production was studied.

[Subsequent mutagenesis under the action of UV rays in a culture of Actinomadura carminata, a producer of carminomycin]. / Posledovatel'nyi mutagenez pod deistviem UF-luchei v kul'ture Actinomadura carminata produtsenta karminomitsina

The succession of some markers on the chromosomes of Actinomadura carminata was shown with the method of successive mutagenesis based on the preferable effect of the mutagen on DNA in the site of replication. The spore germination was synchronized by selection of the spores of the definite size and maintenance at a temperature of 0 degrees. The periods of formation of the highest numbers of morphological and auxotrophic mutants were compared with the time of DNA replication.