Spontaneous and induced variability inStreptomyces nogalater producing nogalamycin

Abstract
Variability in the production of nogalamycin byStreptomyces nogalater var.nogalater was followed in untreated and mutagenized populations of the standard strainNRRL 3035 and its spontaneous variant K-18 using the method of agar blocks with subsequent tests under submerged conditions. In both strains the most active variants were obtained by natural selection without mutagenic treatment; in this way productivity increased by 108% after two selection steps. Treatment with UV-radiation did not yield variants with a highly increased activity. Gamma-radiation extended the variability but, at the same time, substantially increased the number of non-producing and low-producing isolates. Relatively high yields of (+)-variants were obtained after treatment with nitrous acid but their activity did not reach that observed in the most active spontaneous variants.