Transformation of diphenyl ethers by Trametes versicolor and characterization of ring cleavage products

The white-rot fungi Trametes versicolor SBUG 1050, DSM 11269 and DSM 11309 are able to oxidize diphenyl ether and its halogenated derivatives 4-bromo- and 4-chlorodiphenyl ether. The products formed from diphenyl ether were 2 - and 4-hydroxydiphenyl ether. Both 4-bromo- and 4-chlorodiphenyl ether wer e transformed to the corresponding products hydroxylated at the non-halogen ated ring. Additionally, ring-cleavage products were detected by high perfo mance liquid chromatography and characterized by gas chromatography/mass sp ectrometry and proton nuclear magnetic resonance spectroscopy. Unhalogenate d diphenyl ether was degraded to 2-hydroxy-4-phenoxymuconic acid and 6-carb oxy-4-phenoxy-2-pyrone. Brominated derivatives of both these compounds were formed from 4-bromodiphenyl ether, and 4-chlorodiphenyl ether was transfor med in the same way to the analogous chlorinated ring cleavage products. Ad ditionally, 4-bromo- and 4-chlorophenol were detected as intermediates from 4-bromo- and 4-chlorodiphenyl ether, respectively. In the presence of the cytochrome-P450 inhibitor 1-aminobenzotriazole, no metabolites were formed by cells of Trametes versicolor from the diphenyl ethers investigated. Cell -free supernatants of whole cultures with high laccase and manganese peroxi dase activities were not able to transform the unhydroxylated diphenyl ethe rs used.