【作者】 蒋金会；

【导师】 朱鲁生；

【作者基本信息】 山东农业大学 ， 环境科学， 2010， 硕士

【摘要】 本文以有机氯杀虫剂DDT及其初级降解产物DDE作为研究对象,采用富集分离法筛选出一株能够同时降解DDT和DDE的细菌——寡氧单胞菌（Stenotrophomonas sp.）DXZ9,并对该菌株进行了形态学、生理生化及16S rDNA鉴定,还对降解微生物的富集分离、环境条件对DXZ9菌株降解能力的影响以及该菌的降解特性等方面进行了系统的讨论,主要研究内容如下:1.介绍了DDT和DDE的理化性质,国内外应用DDT概况,以及由于其广泛应用所带来的环境污染问题;在对前人工作总结分析的基础上,对DDT和DDE在环境介质中的残留动态、降解代谢、生态毒理及微生物降解进行了全面系统的综述;进而提出了作者要研究的问题。2.通过富集培养法和直接培养法分离出数株DDT和DDE的降解菌,同时研究本实验室内已有的菌株对DDT和DDE的降解能力,最终获得4株DDT的高效降解细菌和2株DDE的高效降解细菌。DDT的降解菌在30℃、中性条件下,5d内对10mg·L^-1的DDT的降解率均达到45%以上,其中以DXZ9、DXZ27、DXZ31对DDT的降解率最高;DDE的2株降解菌在相同条件下对DDE的降解率达到35%以上,其中以DXZ9最高。通过比较最终选定高效降解细菌DXZ9作为下一步深入研究的菌株,通过对其形态、生理生化特征及16S rDNA的分析,最终经过鉴定此菌株属于寡氧单胞菌属（Stenotrophomonas sp.）。3.测定了不同时间、pH、温度及底物浓度对细菌降解能力和生长量的影响。结果表明,该菌株5d内对10mg·L^-1DDT的降解率高达55.0%,对10mg·L^-1DDE的降解率高达39.88%;pH 6.0⁸.0时降解率达到最大,细菌的生长量在中性和偏碱性的条件下较大;在底物浓度为10mg·L^-1时降解率最大,该菌具有较强的耐受能力,当DDT和DDE浓度达到150mg·L^-1时仍能生长;细菌的生长和降解需要适宜的温度,30℃培养时,降解率和生长量最大。4. DDT和DDE初步代谢产物的分析:本研究中通过GC-MS分析,使用PE自带数据库分析系统,结合人工物质解析。初步确定菌株DXZ9对p,p′-DDT的代谢产物可能为p,p′-DDE、p,p′-DDD、1-Hexyl-2- Nitrocyclohexane、9-Methylidenefluorene,DXZ9对DDE的代谢产物可能为1-Hexyl-2-Nitrocyclohexane、9-Methylidenefluorene。更多还原

【Abstract】 In this dissertation, taking DDT and DDE as a model pollutant, a strain of bacterium DXZ9 capable of highly degrading DDT and DDE was screened from the soil sample collected from a pesticide plant after taming and enrichment. Based on analysis of phenotype, physiological and biochemical characters and 16S rDNA, DXZ9 was identified as Stenotrophomonas sp. Degrading-bacteria enrichment and isolation, characterization of biodegradation were studied systematically. The results could be summarized as follows:1. The author introduced the use situation, pollution, mobility in environment, degradation and metabolism, ecological toxicological characteristics and pollutant management of DDT and DDE, which has been applied extensively in the world and recently in China; accordingly author presents the issues that would be investigated.2. DDT and DDE degrading-bacteria were isolated by direct way and selective enrichment from soil exposed to pesticides and soil of pesticides production, and then researched on the bacteria in our laboratory conservation. Four high efficiently degrading DDT strains and two high efficiently degrading DDE strains were isolated by selective enrichment, and the high efficiently degrading DDT strains degrading rates under the condition of 30℃、pH 6.0 8.0 in culture media containing 10mg·L^-1 of DDT in 5d were all above 45%, the high efficiently degrading DDE strains degrading rates were all above 35% in the same condition. In contrast, we choose the strain DXZ9 for further study. We identified DXZ9 as Stenotrophomonas sp. based on analysis of phenotype, physiological and biochemical characters and 16S rDNA.3. The effects of time, pH, temperature and DDT DDE concentration on degradation was determined. The results showed that the degradation rate of DDT by DXZ9 was 55.0% in 5 days, and DDE was 39.88%. The biodegradation rates were the highest when pH value was 6.0⁸.0, DDT and DDE concentration was 10mg·L^-1 and cultivated temperature was 30℃. The growth of bacteria higher with pH from 6.0 to 10.0, and the highest when temperature was 30℃, DDT or DDE concentration was 10mg·L^-1.The strain could survive when DDT or DDE concentration was 150mg·L^-1 and the removed amount of DDT DDE increased with DDT or DDE concentration.4. Analysis of the extracted metabolites. In our research, DDT and DDE metabolites were identified in the test culture medium.更多还原