Interspecific protoplast fusion among macrolide-producing streptomycetes

From auxotrophic and idiotrophic mutants of Streptomyces fradiae (tylosin producer) and Streptomyces sp. AM 4900 (pikromycin producer) or Streptomyces narbonensis (narbomycin producer), prototrophic fusants were obtained at a low frequency by the protoplast fusion technique. In the cross of S. fradiae 261-27E (mycaminose-idiotroph, ilv) and Streptomyces sp. AM 4900 N3-4, (pikronolide-idiotroph, arg), an unstable prototrophic fusant, strain No. 14, produced a macrolide antibiotic which was not produced by the wild type, parent strains, and the productivity was lost within a few times transfer. It was concluded that the fusant was not a recombinant, but a heterokaryon. On the other hand, relatively stable fusants were obtained from the cross of S. fradiae TBM (mycaminose-idiotroph, met) and S. narbonensis NA12US3 (narbonolide-idiotroph, his, str) at a frequency of 3.2 X 10(-5). One of the prototrophic fusants produced narbomycin, which is believed to be due to a result of interspecific recombination.