Dynamics of Reductive Dehalogenating Communities Associated with Dehalorespiration Under Conditions of Competition for Hydrogen

氯化脂肪烃，如四氯乙烯（PCE）和三氯乙烯（TCE）是美国含水层中最丰富的地下水污染物。虽然通过还原性脱卤微生物对这些污染物进行生物修复在许多地点取得了成功，但在许多地点，成功有限。这种有限的成功往往是由于缺乏了解的原位微生物还原脱卤和复杂的生物地球化学过程。Mccartyi（Dhc）是PCE和TCE完全脱氯生成无害乙烯的最重要微生物。作为稀有的缓慢生长的生物圈的成员，Dehalococcoides sp.是严格的厌氧微生物，对还原脱卤高度适应，难以在纯培养中分离，并且以未知的方式代谢整合到支持微生物群落中。这种合作，跨学科的工程和科学研究将提供一个基本的了解缓慢增长，还原脱卤微生物，他们的人口，以及相关的微生物群落在氯乙烯还原脱卤在波动的低浓度的氢，他们的首选电子供体的动态。一个更好的理解将实现由实验确定的分子和有机体的性质的脱卤社区的不同微生物的氢的竞争和开发一个预测的数学模型来模拟微生物群落之间的氢的竞争的组合方法。 预期的结果是一个更深层次的系统水平的理解如何在一个自然的微生物生态系统中，动态变化的不同电子供体和替代电子受体引起的微生物群落和脱卤微生物种群的组成变化。更广泛的影响。 本研究的广泛影响将在三个层面上：1）成功的微生物还原脱卤工程的生物修复与氯乙烯污染的地下水。跨学科的合作研究将为工程更有效的生物修复系统所需的关键数据和建模提供见解。这种结合了分子/实验、统计和数学的方法预计可转用于其他高度优先的环境污染物的工程补救，如氟代烃、重金属或放射性核素; 2）将获得对Dehalococcoides sp.的（生态）生理动态和自然种群结构的基本见解，Dehalococcoides sp.是高度生态位适应的成员，稀有，缓慢生长的生物圈这些研究将使科学家们能够开始构建和回答关于这些微生物的生物学和一般低生长条件下的生命的一些关键问题; 3）参与该项目的学生将接受微生物生理学和分子方法、分子信息分析统计方法、环境工程和生物或地球化学系统数学建模方面的培训。学生将学习工程或微生物学的基础知识作为他们的核心学科，并将接受使用统计方法和建模的培训，以教育下一代合作微生物学家和环境工程师。

Chlorinated aliphatic hydrocarbons, such as tetrachloroethene (PCE) and trichloroethene (TCE) are the most abundant groundwater contaminants of US aquifers. While bioremediation of these pollutants via reductively dehalogenating microorganisms has been successful at many sites, there are numerous sites where the success has been limited. This limited success is frequently due to a lack of understanding of in situ microbial reductive dehalogenation and complex biogeochemical processes. Dehalococcoides mccartyi (Dhc) species appear to be the most important microbes for complete dechlorination of PCE and TCE to the harmless ethene. As members of the rare, slow growing biosphere, Dehalococcoides sp. are strictly anaerobic microbes, are highly niche-adapted to reductive dehalogenation, are difficult to isolate in pure culture, and are metabolically integrated in unknown ways into a supporting microbial community. This collaborative, interdisciplinary engineering and science research will provide a fundamental understanding of the dynamics of slow growing, reductively dehalogenating microbes, their populations, and the associated microbial communities during reductive dehalogenation of chloroethenes at fluctuating low concentrations of hydrogen their preferred electron donor. A better understanding will be achieved by a combined approach consisting of experimentally determining molecular and organismal properties of the competition for hydrogen by different microbes of a dehalogenating community and of developing a predictive mathematical model to simulate the competition for hydrogen among the microbial community. The expected outcome is a deeper systems-level understanding of how in a natural microbial ecosystem, dynamically changing diverse electron donors and alternate electron acceptors cause shifts in composition of the microbial community and populations of dehalogenating microbes. Broader Impacts. The broader impacts of this research will be on three levels: 1) Successful engineering of microbial reductive dehalogenation for bioremediation of groundwater contaminated with chloroethenes. The collaborative interdisciplinary research will provide insights into crucial data and modeling needed for engineering more efficient bioremediation systems. This type of combined molecular/experimental, statistical and mathematical approach is expected to be transferable for engineering the remediation of other high priority environmental contaminants, such fluorohydrocarbons, heavy metals, or radionuclides; 2) Fundamental insights will be obtained into the (eco) physiological dynamics and natural population structure of Dehalococcoides sp. which are members of the highly-niche adapted, rare, slow growing biosphere. Studies will enable scientists to begin to frame and answer some crucial questions on the biology of such microbes and on life under low-growth conditions in general; 3) The students involved in this project will be trained in microbial physiology and molecular methods, statistical methods for the analysis of molecular information, in environmental engineering and in mathematical modeling of biological or geochemical systems. The students will learn the fundamentals either in engineering or microbiology as their core discipline, and will also be trained in using statistical methods and modeling to educate the next generation of collaborative microbiologists and environmental engineers.