Abstract

Bioaccumulation, toxicity and long-range transport of persistent organic pollutants (POPs) is a threat to soil and other ecosystems, therefore removal of such pollutants from soil is required. This study thus aimed to isolate and identify bacteria capable of biodegrading a persistent organic pollutant; dichlorodiphenyltrichloroethane (DDT) from a former DDT production unit. The soil was sampled, transported to Japan through standard protocols and bacteria were isolated and assayed for dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE) degradation. The concentration of DDTs in a composite soil sample was 0.7 mg kg⁻¹. Twenty-four bacterial strains were isolated from DDT-contaminated soil, and one of them, strain 885, showed degradation of DDT but could not degrade DDE after 14 days of incubation. This strain also showed significant degradation of 15.6 µM DDD (degradation rate 55.9%) after 28 days incubation. Further metabolites of DDT including 2,2-bis(p-chlorophenyl) ethanol (DDOH) and 4,4-dichlorobenzophenone (DBP) were detected from a 14-day incubation culture with DDD as initial substrate. Strain 885 also showed degradation of metabolites of DDT including those of DDOH, and DBP. In conclusion, strain 885 successfully degraded DDT; therefore, it can be used for remediation of DDT-contaminated soil.

摘要

持久性有机污染物 (POPs) 的生物积累、毒性和远距离迁移对土壤和其他生态系统构成威胁，因此需要从土壤中去除此类污染物。因此，本研究旨在分离和鉴定能够生物降解持久性有机污染物的细菌；二氯二苯基三氯乙烷 (DDT) 来自一个前 DDT 生产单位。对土壤进行取样，通过标准协议运输到日本，分离细菌并分析二氯二苯二氯乙烷 (DDD) 和二氯二苯二氯乙烯 (DDE) 的降解情况。复合土壤样品中滴滴涕的浓度为 0.7 mg kg ^-1. 从受 DDT 污染的土壤中分离出 24 株细菌菌株，其中一种菌株 885 显示出 DDT 的降解，但在孵育 14 天后不能降解 DDE。该菌株在培养 28 天后也显示出 15.6 µM DDD 的显着降解（降解率 55.9%）。从以 DDD 为初始底物的 14 天孵育培养物中检测到DDT 的其他代谢物，包括 2,2-双（对氯苯基）乙醇 (DDOH) 和 4,4-二氯二苯甲酮 (DBP)。菌株 885 还显示出 DDT 代谢物的降解，包括 DDOH 和 DBP 的代谢物。综上所述，菌株 885 成功降解了 DDT；因此，可用于DDT污染土壤的修复。