Microbial degradation of DDT and its residues—A review

Abstract

Microbial degradation of DDT residues is one mechanism for loss of DDT from soil. In this review pathways for biodegradation of DDT, DDD, and DDE by bacteria and fungi are described. Biodegradation of DDT residues can proceed in soil, albeit at a slow rate. To enhance degradation in situ a number of strategies are proposed. They include the addition of DDT-metabolising microbes to contaminated soils and/or the manipulation of environmental conditions to enhance the activity of these microbes. Ligninolytic fungi and chlorobiphenyl degrading bacteria are promising candidates for remediation. Flooding of soil and the addition of organic matter can enhance DDT degradation. As biodegradation may be inhibited by lack of access of the microbe to the contaminant, the soil may need to be pre-treated with a surfactant. Unlike DDT, little is known about the biodegradation of DDE, and this knowledge is crucial as DDE can be the predominant residue in some soils.

Field Validation of Anaerobic Degradation Pathways for Dichlorodiphenyltrichloroethane (DDT) and 13 Metabolites in Marine Sediment Cores from China

“…The high relative abundances of p,p 0 -DDD (20À56%; Figure 4) suggested that DDD was the major degradation product of DDT under anaerobic conditions, similar to the results reported previously. 1,24 Furthermore, p,p 0 -DDE, p,p 0 -DDMU, p,p 0 -DDNU, and p,p 0 -DDNS peaked around 1995 where the relative abundance of p,p 0 -DDT reached the lowest value, corroborating the likelihood for transformation of p,p 0 -DDT into p,p 0 -DDE, p,p 0 -DDMU, p,p 0 -DDNU and p,p 0 -DDNS. On the other hand, the relative abundance of p,p 0 -DDMS did not show such a pattern, probably indicating that it may undergo a different degradation pathway compared to other metabolites.…”

“…1,4 All these transformations involve reductive dechlorination and have been ratified as the predominant mechanism for DDT transformation under anaerobic conditions. 10 Besides, the present study also favored the degradation pathways of p,p 0 -DDMU to p,p 0 -DDMS and p,p 0 -DDNU to p,p 0 -DDNS through reductive hydrogenation (solid red lines in Figure 3), which have been demonstrated by previous studies.…”

Organic contamination in the greenhouse soils from Beijing suburbs, China

“…This may be attributed to the banned usage of industrial HCHs and DDTs in China for nearly 30 years. However, the half-life of p,p'-DDT in soil is longer than 15 years 28 and DDT together with its metabolites may act as endocrine disruptors, 29 then it is necessary to monitor the status of DDTs in the region continuously.…”

Studies on dechlorination of DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) using magnesium/palladium bimetallic system

“…The isomers of this pesticide are released into the environment during manufacture, formulation and usage. "DDT-residues" (DDTr) that collectively represent the different isomers of DDT, DDD, and DDE are now present at numerous sites all around the world [1]. Low solubility, tendency to partition preferentially into 1 lipophilic phase and presence of chlorine atoms make DDTr highly ecotoxic especially to higher organisms [2].…”

“…"DDT-residues" (DDTr) that collectively represent the different isomers of DDT, DDD, and DDE are now present at numerous sites all around the world [1]. Low solubility, tendency to partition preferentially into 1 lipophilic phase and presence of chlorine atoms make DDTr highly ecotoxic especially to higher organisms [2]. Major mode of toxicity is the attack on central nervous system, interruption with the functions of respiratory system, DNA damage in blood cells and disruption of synthesis and metabolism of endogenous hormones [3][4][5][6].…”