Collaborative Research: Microbial chain-elongation mediated dehalogenation and carbon transformation

合作研究：微生物链延长介导的脱卤和碳转化

• 批准号: 2221828
• 负责人: Matthew Scarborough
• 金额: $ 21.44万
• 依托单位: University of Vermont & State Agricultural College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2221828&HistoricalAwards=false
• 关键词: Collaborative; Research; Microbial; chain; elongation

Chlorinated solvents consist of a large family of chlorinated hydrocarbons that have been used worldwide in large quantities to support various industrial applications. Chlorinated solvents such as perchloroethylene (PCE) and trichloroethylene (TCE) are among the most ubiquitous groundwater contaminants in the United States and worldwide. Bioremediation using Dehalococcoides mccartyi has emerged as a promising technology to treat groundwater contaminated by PCE and TCE. Dehalococcoides mccartyi are anaerobic microorganisms that can reduce and convert PCE and TCE to ethene which can subsequently be mineralized to carbon dioxide by other anerobic and/or aerobic microorganisms present in groundwater. However, Dehalococcoides mccartyi require the use of hydrogen (H2) as a sole electron donor to convert PCE and TCE to ethene. The overarching goal of this project is to investigate the use of microbial chain elongation-mediated dehalogenation as a novel groundwater bioremediation process that leverages the ability of a consortium of anaerobic microorganisms to produce the amount of H2 required to carry out the reduction and conversion of PCE/TCE to ethene using organic substrates such as lactic acids, molasses, and vegetable oil. The successful completion of this project will benefit society through the generation of new fundamental knowledge to advance the development and implementation of more efficient and cost-effective bioremediation technologies for the treatment of groundwater contaminated by chlorinated solvents. Additional benefits to society will be achieved through education and outreach activities including the mentoring of two graduate students and two undergraduate students at Arizona State University and the University of Vermont.Dehalococcoides mccartyi are organohalide-respiring bacteria that utilize halogenated compounds as terminal electron acceptors in an anaerobic respiration process to generate the energy required for their growth using electron donors such as hydrogen (H2). During the last two decades, Dehalococcoides mccartyi have emerged as the most promising microorganisms with capability to carry out the reductive dehalogenation of chlorinated hydrocarbons such as perchloroethylene (PCE) and trichloroethylene (TCE) in contaminated groundwater. However, competing microorganisms (e.g., iron or sulfate reducing bacteria) in groundwater that utilize H2 as electron donor can adversely impact the rate and extent of PCE/TCE dehalogenation and conversion to ethene by Dehalococcoides mccartyi. This competition has been consistently linked to slow rates of PCE/TCE dehalogenation and/or the accumulation of toxic intermediates such as vinyl chloride. Building upon the results of promising preliminary studies, the Principal Investigators (PIs) of this project propose to explore the coupling of microbial chain elongation with reductive dehalogenation with the goal of identifying a consortium of anaerobic microorganisms that can reduce and convert PCE/TCE to ethene while using chain elongation to generate the amount of H2 required to carry out this conversion. To advance this goal, the PIs propose to carry out an integrated experimental and modeling research program to 1) uncover critical metabolic pathways and ecological interactions that govern microbial chain elongation-mediated dehalogenation, and 2) develop and validate computational metabolic models of microbial chain elongation coupled with dehalogenation. The specific objectives of the research are to: 1) Characterize the growth and inhibition kinetics and metabolic networks of a consortium of organo-halide respiring and chain-elongating bacteria that has shown promising potential to convert PCE/TEC to ethene and 2) Unravel the interactions of microbial chain elongation with the competing metabolic pathways of methanogenesis and homoacetogenesis in organo-halide respiring microbial communities. The successful completion of this research has the potential for transformative impact through the generation of new fundamental knowledge and computational metabolic models to advance the development and deployment of groundwater bioremediation by microbial chain elongation-mediated dehalogenation. To implement the educational and training goals of this project, the PIs propose to leverage existing programs at their respective institutions to integrate the findings from this research into an RET (Research Experience for Teachers) program at Arizona State University and an extension program (4-H) at the University of Vermont (UVM) to teach and inspire high school teachers and students to explore the use of microorganisms in environmental remediation. In addition, the PIs plan to leverage existing REU (Research Experiences for Undergraduates) programs at ASU and UVM to recruit undergraduate students from underrepresented groups to work on the project.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

氯化溶剂由一大类氯化碳氢化合物组成，它们已在世界各地大量使用，以支持各种工业应用。四氯乙烯(PCE)和三氯乙烯(TCE)等氯化溶剂是美国和世界范围内最普遍的地下水污染物之一。利用麦卡氏嗜盐球藻生物修复技术已成为治理四氯乙烯和三氯乙烯污染地下水的一种很有前途的技术。麦卡提脱卤球菌属厌氧微生物，可将四氯乙烯和三氯乙烯还原并转化为乙烯，随后可被地下水中存在的其他厌氧和/或好氧微生物矿化为二氧化碳。然而，麦卡提脱卤球藻需要使用氢(H2)作为唯一的电子供体来将PCE和TCE转化为乙烯。该项目的总体目标是研究微生物链延长介导的脱卤化作为一种新的地下水生物修复工艺的使用，该工艺利用一组厌氧微生物的能力，利用乳酸、糖蜜和植物油等有机基质将PCE/TCE还原并转化为乙烯所需的氢气。这一项目的成功完成将使社会受益，因为它将产生新的基本知识，推动开发和实施更有效和更具成本效益的生物修复技术，以处理受氯化溶剂污染的地下水。还将通过教育和外展活动为社会带来更多好处，包括指导亚利桑那州立大学和佛蒙特州大学的两名研究生和两名本科生。麦卡提脱卤球菌属有机卤化物呼吸细菌，它在厌氧呼吸过程中利用卤化物作为终端电子受体，利用氢(H2)等电子供体产生生长所需的能量。在过去的二十年里，麦卡提脱卤球菌属是最有前途的微生物，能够对受污染的地下水中的四氯乙烯(PCE)和三氯乙烯(TCE)等氯代烃进行还原脱卤化。然而，地下水中以氢为电子供体的竞争微生物(例如，铁或硫酸盐还原细菌)可能会对麦卡提嗜盐球藻对PCE/TCE脱卤化和转化为乙烯的速度和程度产生不利影响。这种竞争一直与PCE/TCE脱卤化速度缓慢和/或氯乙烯等有毒中间体的积累有关。在有希望的初步研究结果的基础上，该项目的首席调查人员建议探索微生物链延长与还原脱卤化的耦合，目标是确定一个厌氧微生物联合体，可以减少PCE/TCE并将其转化为乙烯，同时利用链延长来产生进行这一转化所需的氢气量。为了推进这一目标，PIS建议开展一项综合的实验和模拟研究计划，以1)揭示支配微生物链延长介导的脱卤化的关键代谢途径和生态相互作用，以及2)开发和验证微生物链延长与脱卤化耦合的计算代谢模型。这项研究的具体目标是：1)表征有机卤化物呼吸和链长杆菌的生长和抑制动力学和代谢网络，该细菌已显示出将PCE/TEC转化为乙烯的良好潜力；2)揭示有机卤化物呼吸微生物群落中微生物链延长与甲烷生成和同乙酰化竞争代谢途径的相互作用。这项研究的成功完成有可能通过产生新的基础知识和计算代谢模型来促进地下水生物修复的开发和部署，从而通过微生物链延长介导的脱卤化作用产生变革性的影响。为了实现该项目的教育和培训目标，PIS建议利用各自机构的现有计划，将这项研究的结果整合到亚利桑那州立大学的RET(教师研究体验)计划和佛蒙特州大学(UVM)的推广计划(4-H)中，以教授和激励高中教师和学生探索在环境修复中使用微生物。此外，PIS计划利用亚利桑那州立大学和密歇根州立大学现有的REU(本科生研究经验)计划，从代表不足的群体中招募本科生参与该项目。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。