Polycyclic aromatic hydrocarbons were oxidized with a wild type bacterium Bacillus cereus to afford hydroxylated compounds. After incuvation the bacteria was collected by centrifuge and the oxidation was carried out by the addition of the substrate (720 mu M) at 30 degrees C for 24 h (pH 7). The substrates such as naphthalene, methylnaphthalene, dimethylnaphthalene and biphenyl were regioselectively oxidized to give naphthols, naphthylmethanol, (methylnaphtyl) methanol and biphenylols, respectively, in 5-26% yields. The toxicity of the products saturated the yield. The addition of an anion-exchange resin improved the yield of 1-naphthol. Also, 1-naphthol was isolated automatically by using dialysis system with a membrane tube.