Role of Protistan Predation in TCE Biodegradation

摘要/ abstract摘要：作者：Nancy E. kinner提案号：CBET - 1033128机构：University of New hampshih标题：原生生物捕食在TCE生物降解中的作用知识价值环境工程从业者面临的最令人困惑的问题之一是TCE污染地下水场地的生物降解停滞。尽管注入合适的电子供体和微生物（例如KB-1）能够将TCE矿化为CO2，但有时氯化溶剂仍然存在。PI最近的研究表明，本地地下水原生生物（即2-3个ìm纳米鞭毛虫）可以捕食微生物群落的成员，潜在地阻止它们在原位建立足够的丰度来完成完整的TCE矿化。拟议的研究将确定原生生物是否以及在什么条件下可以选择性地捕食关键细菌物种，从而阻止群落完成矿化TCE及其后代所需的一系列生物降解反应。具体而言，研究将确定：(1)原生生物捕食和有机碳有效性对微生物群落结构的影响；(2)原生生物对tce降解菌群中关键物种的选择性放牧，如果是，其速率是多少（水中细菌/原生生物的净除率？h）；(3) TCE和/或其后代在环境相关浓度（10-1000 ìg/L）时，对本地原生生物有抑制作用；(4) tce污染含水层的微生物群落结构也发生了类似的变化；(5)其他tce污染地点原生生物分布相似。本研究的最终目标是制定策略，以避免任何不利影响的捕食对TCE的生物修复。拟进行的研究将使用：(1)微观世界和分子技术；(2)批量进料实验；(3)经典原体毒性试验和连续流动非原位扩散室。PI项目帮助开发了用于研究今天使用的含水层捕食者-猎物关系的主要技术。利用这些资源来解决原生生物捕食关键细菌物种是否会破坏原位TCE生物修复/生物增强的问题，有可能极大地增加我们对地下水生态系统动力学的理解，并提出可能的捕食者避免策略以防止失速（例如，表面关联，改变细胞表面特征以限制猎物偏好）。更广泛的影响该项目将培养一名硕士？将包括两名本科生助理和最多十名本科生完成与本研究相关的个人项目，以满足他们的毕业项目要求。该项目还将包括最多四名中学生，他们将学习环境工程如何依赖多学科科学家团队（微生物学家、水文学家和工程师）在实验设计、数据分析和问题解决方面相互补充技能和方法。（中学生将包括女孩、西班牙裔和/或非裔美国学生）。这项研究将导致建立一个包括真核生物和原核生物在内的受tce污染的地下水含水层分子数据库。这将作为未来TCE污染含水层社区图书馆的基础，并将代表使用分子技术表征TCE污染含水层中原生生物群落的首次尝试之一。本地微生物和受污染沉积物的来源是新罕布什尔州朴茨茅斯的皮斯国际贸易港（原皮斯空军基地），这是一个含有TCE羽流的断裂基岩含水层。尽管已发展出化学和生物改良剂来促进就地生物修复，但对宝贵地下水资源的三氯乙烯污染仍然是一个问题。这一建议是基于最近关于地下水中普遍存在的自然原生生物影响的发现，旨在解决一些受TCE污染的含水层中可能出现的失速原因。

ABSTRACTPI: Nancy E. KinnerProposal Number: CBET - 1033127Institution: University of New HampshireTitle: Role of Protistan Predation in TCE BiodegradationIntellectual Merit One of the most perplexing problems facing environmental engineering practitioners is stalls in biodegradation at TCE-contaminated groundwater sites. In spite of injection of a suitable electron donor and a microbial consortium (e.g., KB-1) able to mineralize TCE to CO2, sometimes the chlorinated solvents persist. The PI's recent research has shown that indigenous groundwater protists (i.e., 2-3 ìm nanoflagellates) can prey upon members of the microbial consortia, potentially preventing them from establishing a sufficient abundance in situ to accomplish complete TCE mineralization. The proposed research will determine if, and under what conditions, the protists can selectively prey upon key bacterial species, preventing the consortia from accomplishing the series of biodegradation reactions necessary to mineralize TCE and its progeny. Specifically, the research will determine if: (1) protistan predation and organic carbon availability have an influence on the microbial community structure; (2) protists selectively graze on key species in the TCE-degrading consortia, and if so, at what rates (nL of water cleared of bacteria/protist?h); (3) TCE and/or its progeny, at environmentally-relevant concentrations (10-1000 ìg/L), inhibit indigenous protists; (4) similar changes in the microbial community structure are observed in a TCE-contaminated aquifer; and (5) similar distributions of protists are observed in other TCE-contaminated sites. The ultimate goal of the research is to develop strategies to avoid any adverse effects of predation on TCE bioremediation. The proposed research will be conducted using: (1) microcosms and molecular techniques; (2) batch feeding experiments; (3) classic protistan toxicity tests and continuous flow ex situ diffusion chambers. The project PI has helped to develop the primary techniques used to study aquifer predator-prey relationships that are used today. Bringing these resources to bear on the question of whether protistan predation of key bacterial species can disrupt in situ TCE bioremediation/bioaugmentation has the potential to greatly increase our understanding of groundwater ecosystem dynamics and suggest possible predator avoidance strategies to prevent stalling (e.g., surface association, change in cell surface characteristics of consortia to limit prey preference). Broader Impacts The project will result in the training of one master?s student and will include two undergraduate assistants and up to ten undergraduates completing individual projects related to this research to fulfill their capstone senior project requirement. This project will also include up to four middle-school students who will learn how environmental engineering depends upon multidisciplinary teams of scientists (microbiologists, hydrologists, and engineers) complementing each others skills and approaches to experimental design, data analysis and problem solving. (The middle-schoolers will include girls and Hispanic and/or African-American students). The research will result in the development of a molecular database for TCE-contaminated groundwater aquifers that will include eukaryotes and prokaryotes. This will serve as the foundation for future community libraries for TCE contaminated aquifers, and will represent one of the first attempts to characterize the protistan community in TCE-contaminated aquifers using molecular techniques. The source of the indigenous microbes and contaminated sediments is Pease International Tradeport (Formerly Pease Air Force Base) in Portsmouth, NH, a fractured bedrock aquifer containing a TCE plume. TCE contamination of precious groundwater resources continues to be a problem in spite of development of chemical and biological amendments to stimulate in situ bioremediation. This proposal, building on recent findings regarding the impact of ubiquitous naturally-occurring protists in groundwater, aims to address a likely cause of stalling in some TCE contaminated aquifers.