Fungal hydroxylation of polychlorinated naphthalenes with chlorine migration by wood rotting fungi.

Biodegradation of the polychlorinated naphthalenes (PCNs) 1,4-dichloronaphthalene (1,4-DCN), 2,7-dichloronaphthalene (2,7-DCN), and 1,2,3,4-tetrachloronaphthalene (1,2,3,4-TCN), by the white-rot fungus Phlebia lindtneri was investigated. 1,4-DCN was metabolized to form six metabolites by the fungus. It was estimated from GC-MS fragment patterns that the metabolites were four putative hydroxylated and two dihydrodihydroxylated compounds. One of the hydroxylated products was identified as 2,4-dichloro-1-naphthol by GC-MS analysis using an authentic standard. This intermediate indicated chlorine migration in a biological system of P. lindtneri. 2,7-DCN was metabolized to five hydroxylated metabolites and a dihydrodihydroxylated metabolite. Significant inhibition of the degradation of DCNs and formation of their metabolic products was observed in incubation with the cytochrome P-450 monooxygenase inhibitor piperonyl butoxide. The formation of the dihydrodiol-like metabolites, chlorine migration and the experiment with P-450 inhibitor suggested that P. lindtneri provides hydroxyl metabolites via benzene oxide intermediates of DCNs by a cytochrome P450 monooxygenase. In addition, P. lindtneri degraded 1,2,3,4-TCN; two hydroxylated compounds and a dihydrodihydroxylated compound were formed.