Genetic relatedness between streptomycin-producing and non-producing strains of Streptomyces griseus, studied by means of DNA-DNA hybridization

Abstract

DNA-DNA hybridization was studied in order to determine the genetic relatedness between a streptomycin-producing and a non-producing mutant of Streptomyces griseus. The latter strain of short vegetative life cycle had been developed from the streptomycin-producing strain by means of nitrogen mustard treatment. Since the two strains differ in several features, we were prompted to examine the sequence homology between their DNAs. Hybridization experiments carried out with the membrane filter method yielded 73.8% and 67.3% DNA homology values, respectively. The results indicate that there is a significant, but not very close, relatedness between the DNA sequences that corresponds to the similarities and differences observed between the phenotypes of the two strains. Further aspects of established homology are also discussed.