[Spontaneous and induced variability of Streptomyces aureofaciens--chlortetracycline producer]. / Spontanna ta indukovana minlyvist' Streptomyces aureofaciens--produtsenta khlortetratsyklinu.

Spontaneous and induced variability of Streptomyces aureofaciens strain T[symbol: see text] 633 [symbol: see text] and its variants has been investigated. Correlative relation between the antibiotic formation and colonies morphology was observed. Combined effect of nitrosoguanidine and UV-beams resulted in the obtaining of 27 variants which exceeded activity of strain T[symbol: see text] 633 [symbol: see text] by 30-35% and were stable as to antibiotic biosynthesis during 7-10 generations.

[The induction of mutations in Streptomyces aureofaciens by UV rays and nitrosoguanidine and the identification of the mutants obtained]. / Induktsiia mutatsii u Streptomyces aureofaciens UF-promenniamy i nitrozohuanidynom ta identyfikatsiia oderzhanykh mutantiv.

Streptomyces aureofaciens 019(8), chlortetracycline producent was subjected to the effect of UV-light and nitrosoguanidine and after that its 121520 colonies have been analyzed by the methods of replicas and 57 mutants were isolated: sensitive to the effect of UV radiation--14; auxotrophs--30; antibiotic-inactive --13. The induction frequency of mutations is within the limits of 0.016 to 0.067%. Auxotrophic mutants manifested genetic instability. Mutants with a block chlortetracyclin biosynthesis are stable.

Mutagénesis con luz ultravioleta (UV) de una cepa del género streptomyces productora de antibiótico / Ultraviolet utagenesis of an antibiotic-producing straing of the genre streptomyces

Se aíslan 6 mutantes auxotróficos por la técnica de plaqueo por réplica después de la mutagénesis con luz ultravioleta (UV). Se señala que en la caracterización todos resultaron alterados en la vía de síntesis de la arginina. Se aíslan 4 revertantes espontáneos de 3 de los mutantes. Se informa que la aplicación del método de Kelner de difusión en agar para determinar la producción antibiótica a mutantes y revertantes y el procesamiento estadístico de los resultados obtenidos, evidenció que no existen diferencias significativas entre la cepa parental y los mutantes, pero sí entre la cepa parental y los revertantes, y produce uno de ellos, el 28-2, significativamente menos que la cepa RA-2. Se indica que el cálculo del coeficiente de variación para los mutantes evidenció una mayor estabilidad de los mutantes 20, 25, 26, y 28 en relación con la cepa parental, y el 25 es 5 veces más estable que éste

Mutagénesis con luz ultravioleta (UV) de una cepa del género streptomyces productora de antibiótico / Ultraviolet mutagenesis of an antibiotic-producing straing of the genre streptomyces

Se aíslan 6 mutantes auxotróficos por la técnica de plaqueo por réplica después de la mutagénesis con luz ultravioleta (UV). Se señala que en la caracterización todos resultaron alterados en la vía de síntesis de la arginina. Se aíslan 4 revertantes espontáneos de 3 de los mutantes. Se informa que la aplicación del método de Kelner de difusión en agar para determinar la producción antibiótica a mutantes y revertantes y el procesamiento estadístico de los resultados obtenidos, evidenció que no existen diferencias significativas entre la cepa parental y los mutantes, pero sí entre la cepa parental y los revertantes, y produce uno de ellos, el 28-2, significativamente menos que la cepa RA-2. Se indica que el cálculo del coeficiente de variación para los mutantes evidenció una mayor estabilidad de los mutantes 20, 25, 26, y 28 en relación con la cepa parental, y el 25 es 5 veces más estable que éste

[Action of chemical and physical mutagenic factors on the tetracycline producer Streptomyces aureofaciens]. / Izuchenie deistviia khimicheskikh i fizicheskikh mutagennykh faktorov na produtsent tetratsiklina Streptomyces aureofaciens.

The mutagenic effects of N-nitrozomethylbiuret (N-NMB), N-nitrozomethylurea (N-NMU), N-nitrozodimethylurea (N-NDMU), ethylene imine and UV light on Str. aureofacients producing tetracycline was studied comparatively. It was shown that N-NMU and N-NMB had a higher toxicity and mutagenic activity as compared to N-NDMU. The toxicity levels of N-NMU and N-NMB were similar. Still, by the number of the morphological mutations induced by them N-NMU was more effective.

Induction of mutations in antibiotic-producing microorganisms by fast neutrons from the U-120 cyclotron.

The purpose of this study was to investigate the activity of fast neutrons from a U-120 cyclotron in the induction of mutations in streptomycetes, resulting in strains with enhanced antibiotic production. Three streptomycete strains producing the antibiotics: lincomycin, moenomycin, and demethylchlorotetracycline were used. Correlation between the survival rate of spores of the examined strains and neutron dose was determined. Several morphological and physiological features (particularly production of antibiotics for 1543 variants derived from the parent strains) and their distribution within the population were also studied. The survival rate of the streptomycetes spores after irradiation with fast neutrons was found to be an individual strain property. Several variants with considerably increased antibiotic yield were isolated. The results are compared with those obtained after treatment with other mutagens. Several variants of one of the strains with a strongly enhanced antibiotic yield (200--220%) were isolated. No such variants were found after UV irradiation.