Involvement of 3,4-dichlorophenol hydroxylase in degradation of 3,4-dichlorophenol by the white rot fungus Phanerochaete chrysosporium

Phanerochaete chrysosporium was able to grow in a C-limited medium containing 3,4-dichlorophenol. In comparison with cultures without 3,4-dichlorophenol, we observed about 30% reduction of the biomass together with the lack of Lignin peroxidase and manganese peroxidase production. A weak dechlorination was observed but only methylated dichloroaromatic products such as 3,4-dichloroanisole, 4,5-dichloroguaiacol, and 4,5-dichloroveratrole were identified as chlorinated metabolites showing that methylation, but also hydroxylation reactions occurred. To confirm this hydroxylation reaction we have studied the degradation of 3,4-dichlorophenol, and of several chlorinated metabolites by mycelial pellets of P. chrysosporium lacking peroxidase activity. Under these conditions the degradation and the dechlorination of 3,4-dichlorophenol increased strongly and the amount of chloride recovered was 80% of the stoichiometric amount recoverable. We observed similar results with 4,5-dichlorocatechol. An NADPH-dependent 3,4-dichlorophenol hydroxylase was detected in cell free extracts and 4,5-dichlorocatechol was identified as hydroxylation product. (C) 1998 Elsevier Science B.V. All rights reserved.