A New Metabolic Pathway of Heptachlor Epoxide Biotransformation by Cordyceps brongniartii ATCC66779

Abstract

Although heptachlor epoxide (HE) is the major metabolite of organochlorine pesticide heptachlor in soil, there is very limited information on the biodegradation of HE by microorganisms, and no systematic study on the metabolic products and pathways for HE transformation by fungi has been conducted. In this study, the metabolism of HE was performed with Cordyceps brongniartii ATCC66779, which is capable of degrading polychlorinated dibenzo-p-dioxin. This fungus removed about 27% and 21% of HE in PDB and BSM medium, respectively, after 20 days of incubation. Three hydroxylated products including heptachlor diol, 1,2-dihydroxydihydrochlordene and trihydroxychlordene were detected as metabolites of HE using GC/MS analysis, suggesting that HE was metabolized to hydrophilic products via hydrolysis, dechlorination and hydroxylation.