[Possibility of the early identification of polyene antibiotic producers]. / O vozmozhnosti rannei identifikatsii produtsentov polienovykh antibiotikov

A method for identification of polyenic antibiotics at early stages of their screening was developed using the known fact of high affinity of polygens and steroids. It was found that addition of cholesterol or ergosterol to the nutrient medium in a concentration of 100 gamma/ml eliminated the inhibitory effect of the polyenic antibiotics. Screening of the antibiotic-producing actinomycetes simultaneously on 2 media, i.e. with and without cholesterol using the yeast test-organisms provided identification of actinomycetes producing polyenic antibiotics. The selective capacity of 3 yeast cultures, i.e. Sacch. cerevisiae, Cand. albicans and Tor. globosa 11-3 as test-organisms for screening polyenic antibiotics was compared. It was shown that mitochondrial mutant 11-3 of Tor. globosa was a highly sensitive model for identification of actinomycetes producing polyenic antibiotic, since 23% of the actinomycetes possessing an activity against that organism produced substances of the polyenic nature. All the strains of the actinomycetes screened with the help of Cand. albicans and Sacch. cerevisia were the same as those detected with the help of mutant 11-3 of Tor. globosa.

[Determination of the biological activity of heliomycin by a method of diffusion in agar]. / Opredelenie biologicheskoi aktivnosti geliomitsina metodom diffuzii v agar

A biological method for determination of geliomycin activity using agar diffusion is described. A nutrient medium containing Hottinger broth up to 35 mg per cent of amine nitrogen, 1.5 percent of agar-agar, tap water, pH 7.8 to 8.0 was used. Bacillus subtilis ATCC 6633 served as the test-culture. Geliomycin was dissolved in 0.1 N sodium hydroxide solution.