Pseudomonas fluorescens S272 newly isolated from a soil sample produced a considerable amount of pyoluteorin and 2,4-diacetylphloroglucinol when grown on ethanol as a single carbon source, The coproduction of approximately 150 mu g/ml of pyoluteorin and approximately 500 mu g/ml of 2,4-diacyl-phloroglucinol was achieved by flask cultutivation in a medium containing approximately 2% ethanol. A high C/N ratio and inorganic phosphate limitation in the medium were also important factors to be considered for optimization of production of the antibiotics.