The Antibiotic Ya-56 Complex: Taxonomy and Production of the Producing Strain

Abstract

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. Ultraviolet 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. In the course of screening for new antibiotics, a complex of antibacterial and antitumor antibiotics was obtained from the culture broth of a streptomycete. This complex, named YA-56, consisted of two main components designated YA-56 X and XA-56Y and at least three other minor components. Further investigation indicated these belonged to the phleomycin-bleomycin group. The present paper deals with the taxonomy and antibiotic production of the producing strain. Isolation and characterization of the main components of the antibiotic YA-56 complex will be reported in a succeeding paper. The antibiotic YA-56 complex-producing strain was characterized by the formation of hygroscopic masses of smooth-walled spores in coils on aerial mycelia. As a result of taxonomic study, the strain was considered as a new variety of Streptomyces humidus, for which the name Streptomyces humidus var. antitumoris Furumai and Okuda var. nov. is proposed. The type strain has been deposited in the Northern