Ultraviolet mutagenesis in Streptomyces coelicolor: induction of reversions in a polyauxotrophic strain.

UV irradiation of the aerial spores of Streptomyces coelicolor pro arg hom cys strain A677 causes the induction of Arg+ and Cys+ revertants. Both phenotypic classes of revertants are induced according to approximately dose-squared kinetics. Some 30% of the induced Cys+ revertants were shown by direct genetic tests to be due to suppressor mutations. Indirect evidence, based on the fact that a high proportion of the UV-induced Arg+ revertants were also simultaneously Hom+, indicates that suppressors are probably also responsible for the Arg+ phenotype of many revertants.