一株DDT降解菌的筛选及其降解特性

以DDT为目标污染物，通过筛选获得了一株效果稳定的DDT降解菌，并对其进行形态学观察，生理生化特性及16S rRNA测序鉴定.经鉴定，该菌株属于甲基菌属（Methylovorus），命名为Methylovorus sp. XLL03.菌株在pH值为7，温度30℃，外加碳源浓度0.5%，初始DDT浓度20mg/L时生长量最大.在pH值为6，温度30℃下，外加碳源（葡萄糖）浓度0.1%，初始DDT浓度20mg/L时对DDT的降解率最大.在优化条件下，4d后菌株XLL03对DDT最高降解率可达50.4%.利用GC-MS对DDT的降解中间产物进行定性分析，初步推断在菌株XLL03中，DDT最初分别通过脱氯和脱氯化氢生成DDD和DDE，随后DDD和DDE进一步脱氯得到DDMU，最终DDMU开环后又经过一系列反应被彻底矿化.在DDT的代谢过程中，未发现代谢中间产物的积累，表明菌株XLL03在修复受DDT污染的水或土壤中具有一定的应用前景.

Screening and degradation characteristics of a DDT-degrading bacteria

DDT was used as the target pollutant, and a strain capable of degrading DDT was obtained by isolation and the identification of the strain was carried out through morphological observation, experiments on physiological and biochemical characteristics and 16S rRNA sequencing. The strain was identified as Methylovorus, and named as Methylovorus sp. XLL03. The best growing condition for the strain was as follow:pH of 7, 30℃, external carbon source concentration of 0.5%, and initial DDT concentration of 20mg/L. The best degradation condition for the strain was as follow:pH of 6, 30℃, external carbon source(glucose) concentration of 0.1%, and initial DDT concentration of 20mg/L. Under the optimized conditions, the highest degradation rate of DDT by strain XLL03 was 50.4% 4 days later. The qualitative analysis of degradation intermediates of DDT was carried out by GC-MS. It was initially concluded that DDT could first be transformed into DDD and DDE via dechlorination and dehydrochlorination respectively, subsequently both DDD and DDE converted to DDMU by further dechlorination, and then after ring opened, DDMU went through a series of reactions was completely mineralized. No metabolic intermediates was found during the metabolism of DDT, which indicating that strain XLL03 has potential application prospects in repairing DDT-contaminated water or soil.