Selection and Improvement of Antibiotic Activity in Streptomyces Erythreus E—29 Strain after the Action of Mutagenic Agents

Streptomyces erythreus E-29 strain was selected by treatment with ultraviolet irradiation, ethylenimiitne and 1,4-diepo xyfoutan e as mutagenic agents. The most effective in improving of the erythromycin yields was ethylenimine in concentration of 0.1 per cent. After 60 min. of treatment with the mentioned mutagen a new strain EE-17 was isolated. On fermentation this strain showed 106 per cent higher yields than the initial one. By ultraviolet irradiation of the strain, 2.06 per cent plus variants were induced. The best isolate was 52 per cent more active in antibiotic activity than the initial strain. As a result of 1,4-diepoxybutane treatment of strain E-29 the maximum frequency of plus variants was 2.66 per cent. It has turned out that at this concentration of mutagen, the frequency of minus variants (33 per cent) greatly exceeded the frequency of the same variants in comparison to the ultraviolet irradiation and ethylenimine treatment. The best variant was 26 per cent more active than the initial strain