Halorespiration of a Natural Organochlorine and Trichloroethylene in a Historically-Uncontaminated Soil

在未来30年内，美国环保署估计，美国将有35万个受污染的场地需要修复，预计成本为2500亿美元。卤化污染物是这些场所最常见的污染源之一。已确定称为卤呼吸器（去卤呼吸器）的微生物可以利用氯代有机物作为生长和能量的电子受体，将有毒的氯代有机物还原为毒性较小或无毒的化合物。虽然halorespirers已被证明是边际有效的生物修复在一些污染的网站，这些微生物持有的潜力仍然没有实现。PI最近发现，在未受污染的土壤中存在大量的Dehalococcoides样微生物，它们在环境中的浓度与存在的天然氯化有机物的数量在统计上相关。这一发现提出了关于未受污染和受污染环境之间联系的问题。本文提出的研究将开始，以解决这些联系，通过检查在未污染的土壤中的生物体halorespire不同的氯化物的能力，调查还原脱卤酶（rdh）基因的转录从未污染的土壤在halorespiration过程中，并确定如何rdh基因，基因转录本，和细菌群落在未污染的土壤中暴露于人为氯化物的变化。据推测，来自未受污染的土壤中的halorespirers可以呼吸氯氧杂蒽酮和三氯乙烯，这两种不同的化合物的呼吸还原脱卤酶是同源的。这项研究将进一步加深我们对盐呼吸的理解，特别是在未污染的环境中。这对修复领域、生态学和地球化学循环具有重要意义。拟议的研究将为一名研究生和一名本科生提供直接的教育效益，培养他们的实验和批判性思维能力，并帮助他们发展为工程师/科学家。此外，在这项研究中获得的结果将被纳入几个类的讲义，包括介绍环境工程，本科土木工程师在明尼苏达大学的必修课，和环境微生物学，一个高层次的本科和低层次的研究生实验室课程。特别是，从这个项目的结果将被纳入生物修复和元素循环的讲座材料。最后，如果成功的话，这项研究可以通过发现用于污染场地生物强化和生物刺激的天然制剂，实现更迅速和更成功的补救。

NovakCBET-0966559Over the next 30 years, the EPA has estimated that 350,000 contaminated sites in the United States will require remediation at a projected cost of $250 billion. Halogenated pollutants are one of the most common sources of contamination at these sites. Microorganisms, called (de)halorespirers, have been identified that can reduce toxic chlorinated organics to less- or non-toxic compounds using chlorinated organics as electron acceptors for growth and energy. Although halorespirers have been shown to be marginally effective for bioremediation at some contaminated sites, the potential that these microorganisms hold remains unrealized. The PI recently discovered that Dehalococcoides-like microorganisms exist in uncontaminated soils at high numbers and that their concentration in the environment statistically correlates to the amount of natural chlorinated organic matter present. This discovery raises questions regarding the links between uncontaminated and contaminated environments. The research proposed herein will begin to address these links by examining the ability of organisms in uncontaminated soils to halorespire different chlorinated compounds, investigating the transcription of reductive dehalogenase (rdh) genes from uncontaminated soils during halorespiration, and determining how the rdh genes, gene transcripts, and bacterial communities change in uncontaminated soils upon exposure to anthropogenic chlorinated compounds. It is hypothesized that halorespirers from uncontaminated soils can respire both chlorinated xanthones and trichloroethylene and that the reductive dehalogenase enzymes used for the respiration of these two different compounds are homologous. This research will further our understanding of halorespiration, particularly in uncontaminated environments. This has critical implications for the remediation field, ecology, and geochemical cycling. The proposed research will provide a direct educational benefit for one graduate student and one undergraduate student, developing their experimental and critical thinking skills and helping them develop as engineers/scientists. In addition, results obtained in this research will be incorporated into the lecture notes of several classes, including Introduction to Environmental Engineering, a required course for undergraduate Civil Engineers at the University of Minnesota, and Environmental Microbiology, an upper-level undergraduate and lower-level graduate laboratory course. In particular, results from this project will be incorporated into lecture material on bioremediation and elemental cycling. Finally, if successful, this research could result in more rapid and successful remediation through the discovery of natural agents for use in bioaugmentation and biostimulation at contaminated sites.