The antibiotic YA-56 complex: taxonomy and production of the producing strain.

A new complex of phleomycin-bleomycin group antibiotics, YA-56, was isolated from the culture broth of a streptomycete designated as strain MCRL 0387 and identified as a new variety of Streptomyces humidus Nakazawaand Shibata in Imamura et al.9 1956. Ultra-violet irradiation of strain MCRL0387 gave a high-yielding mutant which formed blue aerial mycelium instead of the grayish aerial mycelium of the original strain. Fermentative production of the antibiotics YA-56 complex is described.