Biotransformation of 1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane (4,4 '-DDT) on a Sandy Loam Soil using aerobic bacterium Corynebacterium sp.

摘要

1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane (4,4'-DDT) is an organochlorine pesticide known for its health and environmental hazards and recalcitrance. The objective of this study was to investigate the biodegradation potential of 4,4'-DDT in sandy loam soil using the aerobic bacterium Corynebacterium sp. over a full year. Two separate conditions were evaluated 35 mg/kg aged for 60 days and 18 mg/kg aged for 200 days. Destructive samples of the soil and aqueous phase were analyzed at 7, 14, 28 days, 3, 6, 9 months and 1 year. The total DDT degradation results for the inoculated experiments at 35 +/- 9 mg/kg (60 day aged) and 18 +/- 2 mg/kg (200 days aged) concentrations were 7.7 and 5.7 %, respectively. This corresponded to 0.225 and 0.086 mg/year DDT degradation, with the main metabolites observed being DDD (1,1-dichloro-2,2-bis(p-chlorophenyl) ethane) and DDE (1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene). Metabolite formation was minimal, in the interval of 0.008-0.064 mg/year DDE and 0.081-0.302 mg/year DDD. DDT was seen to remain mostly in the soil, while the metabolites were measured only in the aqueous phase. This is believed to be the first documented evidence of Corynebacterium sp. (ATCC 49955) actively facilitating partial DDT degradation.