TCE reductive dehalogenation by a microbial community

微生物群落的 TCE 还原脱卤

• 批准号: 6577810
• 负责人: Margaret Romine
• 金额: $ 10.08万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2003-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6577810
• 关键词: biotransformation; chemical kinetics; chlorine; environmental contamination; environmental toxicology; enzyme activity; ethylenes; gene expression; ground water; halobiphenyl /halotriphenyl compound; halogenation; hazardous substances; hydrolase; microorganism culture; polymerase chain reaction; trichloroethylene; waste treatment

Tetrachloroethene (PCE) and trichloroethene (TCE) are common groundwater contaminants. Under anaerobic conditions these solvents are are transformed by biological reductive dechlorination to dichloroethene isomers (DCEs), vinyl chloride (VC) and sometimes ethene. The original contaminants and their intermediate metabolites are all CERCLA listed hazardous chemicals that are neurotoxic or carcinogenic. Determining the extent of dechlorination under different conditions would be helpful for evaluating the human health risk at individual sites. Ideally, the conditions which promote complete dechlorination to ethene should be ascertained. These conditions are currently unclear and it is this gap in scientific knowledge which this project is designed to address. This project will utilize an enrichment culture developed by Jim Gossett and Steve Zinder at Cornell University, which is known to completely dechlorinate high concentrations of PCE (0.55 mM) and other chlorinated ethenes to ethene. A specific aim of this project is to develop molecular probes that target 16S rRNA genes and reductive dehalogenase genes present in the culture. These probes will be useful for study of the dynamics of the bacterial community and the expression of the dehalogenases in the culture, as electron donors/acceptors and other nutrients are varied. The goal is to find the optimum conditions for dechlorination of PCE, TCE, DCE and especially VC, which accumulates due to its slow rate of dechlorination. The members of the community will be phylogenetically characterized by 16S rRNA typing. Syntrophic relationships between the dechlorinator, Dehalococcoides ethenogenes, and other species will be established by experimentally combining defined members of the community. Presumably, the syntrophic organisms supply electron donor (hydrogen) and nutrients to D. ethenogenes, so these studies will help further define the conditions which produce optimal dechlorination. The presence of other dechlorinators in the Cornell enrichment culture and the anaerobic enrichment culture from Corvalis, Oregon will be assessed by restriction fragment analysis of amplified 16S rRNA, sequencing of selected clones and searching for homology with known dechlorinators. This may lead to the discovery of organisms which dechlorinate VC at a faster rate, or dechlorinate other substrates under different conditions than are optimal for D. ethenogenes.

四氯乙烯 (PCE) 和三氯乙烯 (TCE) 是常见的地下水污染物。在厌氧条件下，这些溶剂通过生物还原脱氯转化为二氯乙烯异构体（DCE）、氯乙烯（VC），有时还转化为乙烯。原始污染物及其中间代谢物均为 CERCLA 列出的具有神经毒性或致癌性的危险化学品。确定不同条件下的脱氯程度将有助于评估各个地点的人类健康风险。理想情况下，应确定促进完全脱氯为乙烯的条件。目前这些情况尚不清楚，该项目旨在解决科学知识方面的这一差距。该项目将利用康奈尔大学 Jim Gossett 和 Steve Zinder 开发的富集培养物，该培养物可将高浓度的四氯乙烯 (0.55 mM) 和其他氯化乙烯完全脱氯为乙烯。该项目的具体目标是开发针对培养物中存在的 16S rRNA 基因和还原脱卤酶基因的分子探针。这些探针将有助于研究细菌群落的动态和培养物中脱卤酶的表达，因为电子供体/受体和其他营养物质是多种多样的。目标是找到四氯乙烯、三氯乙烯、二氯乙烯，特别是由于脱氯速度慢而积累的 VC 的最佳脱氯条件。社区成员将通过 16S rRNA 分型进行系统发育表征。脱氯者、Dehalococcoides ethenogenes 和其他物种之间的互养关系将通过实验组合群落的特定成员来建立。据推测，互养生物为 D.ethenogenes 提供电子供体（氢）和营养物质，因此这些研究将有助于进一步确定产生最佳脱氯的条件。将通过对扩增的 16S rRNA 进行限制性片段分析、对所选克隆进行测序并寻找与已知脱氯剂的同源性来评估康奈尔大学富集培养物和来自俄勒冈州科瓦利斯的厌氧富集培养物中是否存在其他脱氯剂。这可能会导致发现以更快的速度对 VC 进行脱氯的生物体，或者在与 D.ethenogenes 最佳条件不同的条件下对其他底物进行脱氯的生物体。