[Fertility mutants of the turimycin-producing Streptomyces hygroscopicus IMET JA 6599].

In a continuing search for fertility mutants of the turimycin-producer, Streptomyces hygroscopicus, strain IMET JA 6599, from more than 683 pairs of auxotrophic mutants 19 pairs were found to develop colonies after replica plating on selective media. The frequency of recombinant production in mixed cultures on complex medium varies from 10(-6) to 10(-2) in different combinations of S. hygroscopicus mutants. Typical frequencies representing the proportion of recombinant colonies (from spores and/or fragments of substrate mycelium) and a visual indication of the different fertility levels using the familial fertility test method are given in Tables and Figures. Additionally, reversion rates of markers and different types of colonies of fertility mutants used in some S. hygroscopicus crosses will be shown.