New antibiotic-producing streptomycetes, selected by antibiotic resistance as a marker. I. New antibiotic production generated by protoplast fusion treatment between Streptomyces griseus and S. tenjimariensis.

A novel antibiotic was found after performing an interspecific fusion treatment between Streptomyces griseus and S. tenjimariensis by the selection of clones with a unique antibiotic resistance. Nonantibiotic-producing mutants of streptomycin (SM)-producing S. griseus SS-1198 with resistance to SM and istamycin (IS)-producing S. tenjimariensis SS-939 with resistance to kanamycin (KM) were protoplasted, mixed with polyethyleneglycol and regenerated. Resistant clones to both SM and KM were found among spores of the regenerated culture at a frequency of 10(-6). Their growth appearance was identical with that of S. griseus. Antibiotic productivity was found only in clones resistant to both 20 approximately 50 micrograms/ml of KM and 400 micrograms/ml of SM. The antibiotic produced by a selected strain, SK2-52, proved to be different from SM and IS.