[Selection of active strains of Actinomadura carminata, the producer of carminomycin]. / Selektsiia aktivnykh shtammov Actinomadura carcminata--produtsenta karminomitsina.

The method of selecting active strains among a definite group of analogue-resistant mutants was used on the basis of studying the dependence of the carminomycin-producing organism growth and the antibiotic synthesis level on some metabolites. As a result, gamma-ray induced mutants 4 times more active than the parent strains were obtained.

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.

[Spontaneous and induced variability in Actinomyces rubiginosohelvolus, a new producer of the antibiotic rubomycin]. / Spontannaia i indutsirovannaia izmenchivost' Actinomyces rubiginosohelvolus--novogo produtsenta antibiotika rubomitsina.

Mutants possessing 3 times higher activity as compared to the initial culture were obtained as a result of selection of active variants of Act. rubiginosonelvolus, a new organism producing rubomycin against the background of variation induced by N-methyl-N1-nitro-N-nitrozoguinidine, diethylsulphate and their combinations. Further selection among the mutants stable to 6-mercaptopurine and riboflavine resulted in obtaining an active culture No. 3912 at least 7 times more active with respect to rubomycin production than the initial soil culture.