Biodegradation of Dieldrin by Cordyceps Fungi and Detection of Metabolites

Abstract

Twelve strains belonging to the genus Cordyceps were investigated for their ability to degrade organochlorine pesticide dieldrin. Based on the screening results, we further investigated Cordyceps militaris KS-92 and Cordyceps brongniartii ATCC66779 to determine their degradation capacity and metabolic products towards dieldrin. C. militaris KS-92 and C. brongniartii ATCC66779 removed about 45% and 36% of dieldrin in PDB medium, respectively, after 28 days of incubation. A hydrolysis product, 6,7-dihydroxydihydroaldrin, was detected as a initial metabolite of dieldrin in both fungal cultures using GC/MS analysis. C. militaris KS-92 particularly can degrade dieldrin to dihydrochlordenedicarboxylic acid through oxidation of 6,7-dihydroxydihydroaldrin or directly oxidation of dieldrin. The results suggested that dieldrin was metabolized to hydrophilic/low-toxicity products by selected fungi.