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The ability of certain white-rot fungi (WRF) inocula to transform heptachlor and heptachlor epoxide and its application in artificially contaminated soil were investigated. Fungal inoculum of Pleurotus ostreatus eliminated approximately 89 % of heptachlor after 28 days of incubation, and chlordene was detected as the primary metabolite. The fungal inoculum of Pleurotus ostreatus had the highest ability to degrade heptachlor epoxide; approximately 32 % were degraded after 28 days of incubation, and heptachlor diol was detected as the metabolite product. Because Pleurotus ostreatus transformed heptachlor into a less toxic metabolite and could also effectively degrade heptachlor epoxide, it was then selected to be applied to artificially contaminated soil. The spent mushroom waste (SMW) of Pleurotus ostreatus degraded heptachlor and heptachlor epoxide by approximately 91 and 26 %, respectively, over 28 days. This finding indicated that Pleurotus ostreatus SMW could be used to bioremediate heptachlor- and heptachlor epoxide-contaminated environments.

Abstract: The ability of Pleurotus ostreatus to transform heptachlor as well as heptachlor epoxide was investigated. Heptachlor was eliminated completely by this fungus in potato dextrose broth (PDB) and high nitrogen (HN) media during a 14 d incubation period. Heptachlor epoxide was detected as the main metabolite besides chlordene and 1-hydoxychlordene. Based on identification of the metabolites, transformation of heptachlor was proposed which was initially metabolized by epoxidation, dechlorination and hydrolysis. This fungus was also capable of degrading heptachlor epoxide which is a recalcitrant metabolite of heptachlor. Approximately 9%, 8% and 31% of heptachlor epoxide was eliminated by P. ostreatus in low nitrogen (LN), HN, and PDB media during 14 days of incubation, respectively. After acetylation, the metabolite, 2,3-dihydroxyheptachlor (Heptachlor diol), was detected in the PDB medium cultures, suggesting the hydrolysis reaction occurred in the epoxide ring. This indicated that P. ostreatus is a potential source for transformation of heptachlor as well as heptachlor epoxide. [Copyright &y& Elsevier]