Polyketomycin, a new antibiotic from Streptomyces sp. MK277-AF1. I. Taxonomy, production, isolation, physico-chemical properties and biological activities.

A new antibiotic designated polyketomycin was isolated from the culture broth of Streptomyces sp. MK277-AF1. It was purified by ethyl acetate extraction, Sephadex LH-20 column chromatography and centrifugal partition chromatography (CPC). It inhibited growth of Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA). Its MICs were less than 0.2 microgram/ml. Polyketomycin exhibited cytotoxic activity against nine tumor cell lines at concentrations of 0.9-5.2 micrograms/ml.