Oxygenase is useful when oxygen Is to be introduced at a nonactivated carbon-hydrogen bond to give an optically active center. To obtain such an enzyme from microorganisms, we screened soil samples for organisms that assimilated methylethylketone as their sole carbon source. Yeasts and molds that converted ethylbenzene and propylbenzene into their respective oxygenated products during incubation together as resting cells were isolated. One particularly potent strain was identified as Fusarium moniliforme. The fungus oxidized the side chains of ethylbenzene and propylbenzene selectively at the benzylic position. The products were found to be 1-phenylethanol and 1-phenylpropanol, respectively, by CC-MS and HPLC with a chiral column, with 100% enantiomeric excess of the (R)-(+)-form.