Biodegradation Kinetics of DDT in Soil under Different Environmental Conditions by Laccase Extract from White Rot Fungi

Abstract

Biodegradation of 2,2-bis( p-chlorophenyl)-1,1,1-trichloroethane (DDT) in soil by laccase extract from white rot fungi under different experimental conditions was investigated. DDTs, which stands for the sum of p,p′-DDE, o,p′-DDT, p,p′-DDD and p,p′-DDT in soil was degraded efficiently, and the residue decreased rapidly during the first 15 days and then slowly during the period of 16-25 days. The biodegradation of DDTs in soil fitted the pseudo-first-order kinetics. For 5, 10, 15 and 25 days of incubation with laccase, the residue of DDTs in soil under different atmospheres was decreased by 20%-33%, 34%-52%, 41%-61% and 41%-69% respectively, under different flooding conditions that was decreased by 12%-17%, 17%-30%, 30%-45% and 35%-52% respectively, and for different soils that was decreased by 25%-34%, 39%-53%, 44%-58% and 47%-62% respectively. The half-life of DDTs in soil ranged from 15.07 to 32.95 days under O 2, air or N 2 atmospheres, 23.07 to 40.71 days under different flooding conditions, and 18.78 to 28.88 days for different soils. Laccase is an efficient and safe agent for bioremediation of DDT-contaminated soil.