Biodegradation and bioconversion of endrin by white rot fungi,Phlebia acanthocystis and Phlebia brevispora

Endrin is persistent organic pollutants that contaminate soil in many parts of the world. In this study, endrin was used as the substrate for a degradation experiment with the white rot fungi of the genus Phlebia. The results of tolerance test showed that the tolerance level of Phlebia acanthocystis and Phlebia brevispora to endrin was higher than that of other fungi, and the tolerance coefficient of both strains to 1.0 mg/L endrin exceeded 0.9 in solid PDA medium. P. acanthocystis and P. brevispora could degrade endrin efficiently in pure culture, especially P. acanthocystis had the highest degradability of more than 80% after 20 d incubation. Compared with low-nitrogen medium, PDB medium is more suitable for the biodegradability of two fungi. Several hydroxylated products such as 8-hydroxyendrin and two monohydroxyendrin were detected, indicating that endrin was initially branched to different monohydroxylated products in fungal degradation. Moreover, a carboxylic acid product was obtained from P. acanthocystis culture, suggesting that the carboxylation reaction occurred in bioconversion of endrin. The fungal cytochrome P450 enzymes play significant role in the in the initial hydroxylation process on endrin degradation. This is the first report that endrin is converted to hydroxylated and carboxylated metabolites by microorganisms.