Bioconversion of Heptachlor Epoxide by Wood-Decay Fungi and Detection of Metabolites

Abstract

Although heptachlor epoxide is one of the most persistent organic pollutants (POPs) that cause serious environmental problems, there is very limited information of the biodegradation of heptachlor epoxide by microorganisms, and no systematic study on the metabolic products and pathway of endrin by microorganisms has been conducted. Wood-decay fungi can degrade a wide spectrum of recalcitrant organopollutants, including polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated biphenyls (PCBs). In this study, 18 wood-decay fungi strains of genus Phlebia were investigated for their ability to degrade heptachlor epoxide, and Phlebia acanthocystis, Phlebia brevispora, Phlebia lindtneri and Phlebia aurea removed about 16, 16, 22 and 25% of heptachlor epoxide, respectively, after 14 days of incubation. Heptachlor diol and 1-hydroxy-2,3-epoxychlordene were detected in these fungal cultures as metabolites by gas chromatography and mass spectrometry (GC/MS), suggesting that the hydrolysis reaction in the epoxide ring and substitution of chlorine atom with hydroxyl group in C1 position occur in bioconversion of heptachlor epoxide by selected wood-decay fungi, respectively. This is the first report describing the metabolites of heptachlor epoxide by microorganisms.