DEGRADATION OF PHENOL BY YEAST RHODOTORULA

The effect of phenol on the growth and oxygen uptake rate was studied in several strains in the genus Rhodotorula, and the degradation route of phenol by two yeast strains of Rhodotorula rubra was examined. Rhodotorula rubra IFO 0870, 0889, 0892, 1100 and 1101 grew well in medium containing 250 mg/l phenol. Rhodotorula rubra IFO 0870 still showed a small growth even in medium containing 1,000 mg/l phenol. It was found that oxidation of phenol in the cells of Rhodotorula rubra was partially inhibited by bipyridyl. Phenol metabolites were separated and identified using high performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS). The two phenol metabolites were identified as catechol and cis,cis-muconic acid. These findings suggest that phenol is hydroxylated prior to ring-cleavage and that a catechol branch in beta-ketoadipate pathway exists in the yeast strains. Catechol may be oxidized by the "ortho type" of ring fission.