Isolation of chromomycin A3 from a new subspecies of Streptomyces

A streptomycete contaminant in a marine fungal culture was found to exhibit antibiotic activity against gram-positive bacteria and mycobacteria. The active principle was determined to be a mixture of as many as 12 components which exhibited properties characteristic of the aureolic acid group of antibiotics. Chromatographic comparisons using reference materials revealed the major and second components of the antibiotic mixture to be indistinguishable from chromomycins A3 and A2, respectively. The major component was isolated using a series of column chromatographic and preparative tlc separations. Confirmation of the identity of the major antibiotic as chromomycin A3 was based on elemental analysis, optical rotation, spectral (uv, ir and nmr) characteristics, and properties of an acetate derivative.