Collaborative Research: Stable isotope-based differentiation of vinyl chloride assimilators from cometabolizers in contaminated groundwater

合作研究：基于稳定同位素区分受污染地下水中的氯乙烯同化剂和共代谢剂

• 批准号: 1233087
• 负责人: Timothy Mattes
• 金额: $ 21.43万
• 依托单位: University of Iowa
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2017-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1233087&HistoricalAwards=false
• 关键词: Collaborative; Research; Stable; isotope; based

1233087/1233154Mattes/CupplesVinyl chloride (VC) is a known human carcinogen and a common groundwater contaminant. This research project focuses on identifying and characterizing the key microorganisms involved in VC bioremediation at field sites. VC plumes are generated under anaerobic conditions via reductive dechlorination of chlorinated solvents, but often escape into downgradient aerobic groundwater zones. Aerobic, growth-coupled VC-oxidizing (i.e. VC assimilating) bacteria are readily isolated from VC-contaminated sites, supporting the idea that they play a role in the degradation. However, direct evidence that VC-assimilating bacteria are present and active in situ remains elusive. Further, it is unclear if VC-assimilating isolates are the dominant microbes in the subsurface or if their cultivation is a result of enrichment bias. Also, VC-assimilators cannot be distinguished from the larger related group of ethene-oxidizers, which are fortuitous VC oxidizers. To address these knowledge gaps, this research will use stable isotope probing (SIP) to differentiate VC-assimilating bacteria from bacteria that fortuitously oxidize VC (i.e. the cometabolizers). SIP involves microbial assimilation of 13C labeled substrates into nucleic acids during growth-coupled biodegradation. Following this, 13C labeled nucleic acids are analyzed to identify the organisms responsible for contaminant degradation. The central hypothesis is that SIP techniques, when used in conjunction with existing molecular tools, will differentiate between etheneotrophs and VC-assimilators in both laboratory and field-based applications. The research involves the following specific aims: i) to use soil and/or groundwater samples from VC-contaminated sites andapply DNA-SIP to reveal the presence, identity, and activity of VC-assimilating microorganisms, ii) to use both VC-assimilating and cometabolizing laboratory cultures to develop a SIP-based assay that differentiates between these closely related microbial groups and iii) to provide direct evidence that VC-assimilating bacteria are present and active in situ. Groundwater contamination by toxic pollutants is a major societal problem that threatens human health and the environment. In situ bioremediation practice hold promise for restoring groundwater to pre-contamination levels. Studies aimed at better understanding the presence, abundance and activity of biodegrading microbial communities will serve to bridge fundamental science and the practice of bioremediation. The long-term goal of this research is to advance the bioremediation field by developing molecular tools to characterize pollutant-degrading microorganisms in the environment. The research will involve the training of undergraduate and graduate environmental engineering students to apply molecular biology tools to environmental problems. The work will increase the number of underrepresented minority students and will also involve the development of K-12 outreach activities. The research will benefit society by addressing anthropogenic deterioration of water quality by groundwater pollutants.

1233087/1233154Mattes/Cupples 氯乙烯 (VC) 是一种已知的人类致癌物和常见的地下水污染物。该研究项目的重点是鉴定和表征现场 VC 生物修复所涉及的关键微生物。 VC 羽流是在厌氧条件下通过氯化溶剂的还原脱氯产生的，但通常逃逸到梯度下降的需氧地下水区域。需氧、生长耦合的 VC 氧化（即 VC 同化）细菌很容易从 VC 污染位点中分离出来，这支持了它们在降解中发挥作用的观点。然而，证明 VC 同化细菌存在且原位活跃的直接证据仍然难以捉摸。此外，尚不清楚 VC 同化菌株是否是地下的主要微生物，或者它们的培养是否是富集偏差的结果。此外，VC 同化剂无法与更大的相关乙烯氧化剂组区分开来，乙烯氧化剂是偶然的 VC 氧化剂。为了解决这些知识差距，本研究将使用稳定同位素探测 (SIP) 来区分 VC 同化细菌和偶然氧化 VC 的细菌（即共代谢菌）。 SIP 涉及在生长耦合生物降解过程中微生物将 13C 标记底物同化为核酸。随后，对 13C 标记的核酸进行分析，以确定负责污染物降解的生物体。中心假设是，SIP 技术与现有分子工具结合使用时，将在实验室和现场应用中区分乙烯营养菌和 VC 同化菌。该研究涉及以下具体目标：i) 使用来自 VC 污染地点的土壤和/或地下水样本，并应用 DNA-SIP 来揭示 VC 同化微生物的存在、身份和活性，ii) 使用 VC 同化和共代谢实验室培养物来开发基于 SIP 的检测方法，以区分这些密切相关的微生物群，以及 iii) 提供直接证据： VC 同化细菌存在并在原位活跃。有毒污染物污染地下水是威胁人类健康和环境的重大社会问题。原位生物修复实践有望将地下水恢复到污染前的水平。旨在更好地了解生物降解微生物群落的存在、丰度和活性的研究将有助于架起基础科学和生物修复实践的桥梁。这项研究的长期目标是通过开发分子工具来表征环境中污染物降解微生物，从而推进生物修复领域。该研究将涉及培训环境工程本科生和研究生将分子生物学工具应用于环境问题。这项工作将增加代表性不足的少数族裔学生的数量，还将涉及开展 K-12 外展活动。该研究将通过解决地下水污染物造成的人为水质恶化问题造福社会。