Study Of Applying Bacteria Strain JW2 And NS In Remediation Of Endosulfan-contaminated Soil

The object of the paper is endosulfan. It studied the applying of endosulfan-degrading bacteria JW2 and NS in situ remediation of endosulfan-contaminated soil. The degaradation of endosulfan by JW2 and NS, the colonization of JW2 and NS in soils, the toxicity of endosulfan after degradation and the metabolites were studied. The results were as follows:(1) The degradation of endosulfan by JW2 and NS in situ remediation. The degrading bacteria JW2 and NS were isolated by our laboratory. The research had four treatments of natural soils(CK), natural soil with endosulfan(NE), natural soil with endosulfan and JW2(NEJ),natural soil with endosulfan and NS(NEN). The soil samples were collected at 0?10?20?30?40?50?60?70?80 and 90 d to extract the residual endosulfan in soil. The results showed that the half-life of ?-endosulfan in NE, NEJ, NEN were 43.4?24.6 and 21.9d;the half-life of ?-endosulfan were 95.7?38.0 and 37 d.It appears that JW2 and NS was able to degrade ?- and ?-endosulfan and promoted this degradation. Moreover, the degradation of endosulfan by JW2 was faster than that by NS.(2) The way of PCR-DGGE was applied in investigating the colonization of strain JW2 and NS in soil. The study investigated the survival of strain JW2 and NS in 10,40,70,90 d.The results showed that the target bands of JW2 and NS were clear and bright,indicating that JW2 and NS could successfully colonize in the natural soils.(3) The study used comet assay and micronucleus test to determine the toxicity of endosulfan after degradation. The comet assay was used to demonstrate the degree of DNA damage induced by endosulfan. The micronucleus test was applied to evaluate the damage of chromosome induced by endosulfan. The Eisenia foetida was choosed as experimental material and the method of extraction by organic solvent was used. Through exposure of the filter paper method, earthworms degree of DNA damage were detected by comet assay. The effect of endosulfan on earthworm was tested on the 10,40,70 and 90 d. The results show that the olive tail moment(OTM) of the treatment with strain was shorter than that of the treatment without strain.The genetic toxicity of the soil significantly reduced after inoculation of JW2 and NS.(4) In our research, endosulfan metabolites were identified by GC-MS. In the NE treatment, endosulfan ether and endosulfan sulfate were the metabolites. The results show that endosulfan lactone and endosulfan ether was detected as the end product, with the intermediate metabolite endosulfan sulfate in the NEJ and NEN treatment.The results suggest that strain JW2 and NS might degrade endosulfan by oxidation and hydrolysis pathway and they were able to degrading endosulfan sulfate.