[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.

[Developmental cycle and the cytomorphological characteristics of the oleandomycin producer Streptomyces antibioticus].

The developmental cycle and cytomorphological features of the industrial strain OL-1 and its variant 0968 of the oleandomycin-producing organism were studied. Variant 0968 was obtained as a result of exposure of the spores of strain OL-1 to UV light. When grown under submerged conditions in flasks with the rich medium, the strains were characterized by a complete developmental cycle consisting of three generations of the hyphae.

[Morphological and biochemical characteristics of Streptomyces hygroscopicus mutants induced by streptomycin and hygromycin B].

Under the effect of streptomycin and hygromycin B there were obtained morphological mutants of Str. hygroscopicus differing in their capacity for synthesis of the antibiotic and a complex of proteolytic enzymes, as well as their resistance to high concentrations of the antibiotics. The mutation of resistance to the aminoglycosides with preservation of the initial phenotype did not result in significant changes in biosynthesis of hygromycin B and the enzyme.

[Morphological and biochemical characteristics of Streptomyces hygroscopicus mutants obtained under the action of acridine orange and mitomycin C].

The purpose of this work was to study the action of acridine orange and mitomycin C on the production of mutants of Streptomyces hygroscopicus, strain 0681. The mutagen activity of mitomycin C was shown to be high. The vegetative culture grown for 24 hours produced more mutants under the action of mitomycin C than spores did.

[Action of mitomycin C on the variability of Actinomyces hygroscopicus in forming a proteolytic complex of hygrolytin enzymes and the antibiotic, hygromycin B].

The lethal and mutagenic effect of mitomycin C in doses of 10 and 15 micrograms/ml on the spores and 24-hour culture of Act. hygroscopicus, strain O878 producing hygrolytin, a proteolytic enzyme and hygromycin B, an antibiotic was studied. It was found that mitomycin C had a high lethal effect on the organism.

[Use of antibiotics in selecting a nystatin producer].

The lethal and mutagenic effect of streptomycin and nystatin on Act. noursei, strain 408 producing nystatin was studied. The survival of the spores of strain 408 on the medium with streptomycin decreased with an increase in the antibiotic concentration.

[Postradiation effect of caffeine on the producer of mycoheptin, Streptoverticillium mycoheptinicum].

The modifying effect of caffeine on irradiated spores of Streptoverticillium mycoheptinicum, producing mycoheptin was found. Postradiation treatment of the strain O883: spores with caffeine resulted in decreased survival of the spores proportionally to the radiation dose increase and postradiation caffeine treatment. An increase in the frequency of the morphologically changed colonies, as well as the low and highly active variants with respect to mycoheptin production was observed.

[Lethal and mutagenic action of N-nitroso-N-methylbiuret on the producers of levorin, amphotericin and mycoheptin].

The lethal and mutagenic effect of N-nitrozo-N-methylbiuret (NMB) on the organisms producing levorin, amphotericin B and mycoheptin was studied. The mutagen effect depended on the dose, culture and physiological state of the spores. NMB had a low mutagenic effect on the levorin-producing organism characterized by high activity and genetic homogenicity with respect to the colony morphology and antibiotic production.

[DNA content in Streptoverticillium mucoheptinicum spores in the period of their germination].

Changes in the DNA content were studied in the spores of Streptoverticillium mycoheptinicum. The content of DNA increased in the spores when they were incubated in a liquid nutrient medium at 28 degrees C for 5 hours. Changes in the DNA content during germination of spores corresponded to individual stages: at the stage of activation, the replication of DNA only commenced; at the stage of initiation, the content of DNA doubled in the majority of spores in the population.

[Selective action of novobiocin on Act. levoris, the producer of levorin and levoristatin].

The effect of sodium novobiocin on Act. levoris, strain LIA 0868 producing levorin and levoristatin was studied. High lethal effect of the antibiotic on Act.

[Dependence of the lethal and mutagenic effect of mitomycin C and UV rays on the Streptoverticillium mucoheptinicum spore germination process].

The lethal and mutagenic effects of the DNA-tropic antibiotic mithomycin C and UV-light on Streptoverticillium mycoheptinicum during the period of the spore replication were studied. The spores were more stable to the effect of the mutagens during DNA replication after 120 minutes of incubation. The mutagenic activity of mithomycin C and UV-light was closely connected with the quantitative changes in the genetic material of the pores.

[Lipid makeup of the initial and selected strains of Actinomyces levoris and Streptoverticillium mycoheptinicum in the process of antibiotic synthesis].

The study of the lipid composition showed that the rate of the changes in the fatty acid composition of neutral lipids and phospholipids in the selected strains was higher than that in the initial strains. The medium composition had the decisive effect on the fractional and fatty acid spectrum of the mycelium lipids. When the antibiotic-producing organisms were grown on the synthetic medium the phospholipids were the predominating fractions (70--90 per cent of the total lipids), while with the use of organic medium they amounted only to 30--40 per cent.

[Variability of Act. noursei, the producer of nystatin, under the influence of the separate and combined actions of hydrogen peroxide and UV rays].

The lethal and mutagenic effect of hydrogen dioxide used alone and in combination with UV light on the nystatin-producing strain 408 of Act. noursei was studied. The spore survival decreased with an increase in the hydrogen dioxide concentration and the irradiation dose.

[Action of hygromycin B on the producers of levorin and mycoheptin].

The effect of hygromycin B on survival and variation of the levorin and mycoheptinproducing organisms, i.e. Act levoris, strains 28 and PR-52/67 and streptoverticcium mycoheptincium, strain 44B/I was studied.

[Production in an Actinomyces levoris culture under the action of an actinophage specific to it of variants with stable preservation of its resistance to the phage].

Act. levoris 28, an organism producing levorin was treated with an actinophage virulent to it. Variants of the organism were isolated from the secondary growth of the culture.

[Variability of the levorin producer, Actinomyces levoris Krass].

Natural variation of the levorin-producing organism Act. levoris, strain 28 was studied with respect to the colony morphology and production of levorin and levoristatin. The population of strain 28 consisted of 3 morphological colony types, the main type amounting to 99.