OCE-PRF Uncovering the Genetic Basis of Novel Oxidative Extracellular Electron Transfer Mechanisms in an Electrochemically Active Marine Bacterial Consortium

OCE-PRF 揭示电化学活性海洋细菌群落中新型氧化细胞外电子转移机制的遗传基础

• 批准号: 2126677
• 负责人: Joshua Sackett
• 金额: $ 29.84万
• 依托单位: University of Cincinnati Main Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2126677&HistoricalAwards=false
• 关键词: OCE; PRF; Uncovering; Genetic; Basis

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Recently, it was discovered that some microbes are capable of respiring (‘breathing’) or deriving energy (‘eating’) from solid-phase minerals located outside the cell. This is facilitated by extracellular electron transfer (EET): the process by which some microbes shuttle electrons into and out of their cells from/to solid materials. EET can be evaluated in a laboratory setting, in which microbes are grown on electrodes and the generation of biological current – the flow of electrons to/from the electrode – can be measured. In these experiments, the electrodes are poised at specific voltages (redox potentials) that function as proxies for mineral surfaces. Much of our knowledge of EET has been obtained from just a few model organisms capable of respiratory mineral reduction, in which electrons are transferred out of the cell onto oxidized solid-phase materials, such as iron and manganese oxides, which are prevalent in freshwater and marine sediments. However, little is known about the mechanism or ecological implications of oxidative EET, the process by which electrons are transferred from reduced minerals into the cell as a source of energy (‘eating’). Evidence from microbial community surveys suggests that organisms inhabiting a wide variety of habitats, including both freshwater and marine environments, may be capable of EET. This project will expand upon our understanding of the genetic basis of oxidative EET in microbes isolated from marine sediments grown individually and in a co-culture consortium. Further, this information will provide insight into the role of EET in global elemental cycling and may inform alternative clean energy generation, bioremediation, and wastewater treatment efforts using electrochemically active organisms. This project will provide educational and training opportunities to undergraduate students, who will be recruited to aid with research tasks. Community outreach activities, particularly in underserved areas of Cincinnati, will be organized to provide middle-school aged children with hands-on educational opportunities focused around electromicrobiology and bioenergy production.The discovery of extracellular electron transfer (EET) has important implications for a wide range of biogeochemically important processes. In marine subsurface sediments, where microbial biomass is estimated to account for 0.6% of the total biomass on Earth, lithotrophic metabolisms are difficult to detect since the genetic basis of oxidative EET remains largely unknown and uncharacterized, and ‘omics’ studies fail to identify genes or proteins involved in this process. This significant knowledge gap, coupled with direct measurements of microbial metabolism in the ‘deep’ and ‘dark’ ocean far exceeding the expected models based on the influx of organic carbon to the system, strongly suggest that the importance of lithotrophic metabolisms, and the mechanisms by which these metabolisms operate, has been overlooked and understanding and detection of these processes in nature is crucial. Furthermore, the ecology of EET in polymicrobial communities is poorly understood, but a variety of data imply that diverse microbial communities are important for stable and processive environmental function. Thus, the overarching goal of this project is to gain insight into the genetic basis of EET in oxidative processes, and into the ecological implications of these processes, in two genetically tractable, electrode-oxidizing lithotrophic marine sediment bacteria in pure culture and in co-culture. Cutting-edge, targeted high-throughput sequencing techniques will be used to identify genes putatively involved in oxidative EET and genes that facilitate interspecies electron transfer in co-cultures. Gene deletion mutants will be constructed, and mutant strains will be assayed for their capacity for oxidative EET and interspecies electron transfer. Not only will this allow for a better understanding of microbial community ecology in marine systems, but this study will also provide insight into oxidative EET in a wide array of habitats, including marine and terrestrial subsurface environments and engineered environments where reduced electron sources are prevalent. From an applied and biotechnological standpoint, results from this work will enhance the capacity for evaluating microbe-electrode interactions in genetically tractable organisms, and may inform industrial applications of electrochemically active organisms, such as clean energy generation, wastewater treatment, and electrosynthesis.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.

该奖项全部或部分由2021年美国救援计划法案（公法117-2）资助。最近，人们发现一些微生物能够从细胞外的固相矿物质中呼吸（“呼吸”）或获取能量（“进食”）。这是由细胞外电子转移（EET）促进的：一些微生物将电子从固体材料穿梭进出其细胞的过程。EET可以在实验室环境中进行评估，其中微生物在电极上生长，并且可以测量生物电流的产生-电子流向/来自电极的流动。在这些实验中，电极处于特定的电压（氧化还原电位），作为矿物表面的代表。我们对EET的大部分知识都是从少数能够进行呼吸性矿物质还原的模式生物中获得的，其中电子被转移到细胞外的氧化固相材料上，如铁和锰的氧化物，这些物质在淡水和海洋沉积物中普遍存在。然而，人们对氧化EET的机制或生态学意义知之甚少，EET是电子从还原矿物质转移到细胞中作为能量来源（“进食”）的过程。来自微生物群落调查的证据表明，栖息在各种生境（包括淡水和海洋环境）的生物可能具有EET能力。该项目将扩大我们对从单独生长的海洋沉积物和共培养财团中分离的微生物中氧化EET的遗传基础的理解。此外，这些信息将提供深入了解EET在全球元素循环中的作用，并可能为使用电化学活性生物体的替代清洁能源发电，生物修复和废水处理工作提供信息。该项目将为本科生提供教育和培训机会，他们将被招募来协助研究任务。社区外展活动，特别是在辛辛那提服务不足的地区，将组织提供中学年龄的儿童与实践的教育机会，重点围绕电微生物学和生物能源production.The细胞外电子转移（EET）的发现具有重要意义的广泛的地球化学的重要过程。在海洋地下沉积物中，微生物生物量估计占地球总生物量的0.6%，岩石营养代谢很难检测，因为氧化EET的遗传基础在很大程度上仍然未知且未表征，并且“组学”研究未能确定参与这一过程的基因或蛋白质。这一重大的知识差距，再加上直接测量微生物代谢的“深”和“暗”的海洋远远超过预期的模型的基础上涌入的有机碳的系统，强烈表明，石养代谢的重要性，这些代谢的运作机制，已被忽视和理解和检测这些过程中的性质是至关重要的。此外，EET在多微生物群落的生态学知之甚少，但各种数据表明，不同的微生物群落是重要的稳定和进行性的环境功能。因此，该项目的总体目标是深入了解EET在氧化过程中的遗传基础，以及这些过程的生态影响，在两个遗传上易于处理的，电极氧化石养海洋沉积物细菌的纯培养和共培养。尖端的，有针对性的高通量测序技术将被用来确定参与氧化EET和基因，促进种间电子转移共培养的基因puridine。将构建基因缺失突变体，并测定突变菌株的氧化EET和种间电子转移能力。这不仅可以更好地了解海洋系统中的微生物群落生态，而且这项研究还将深入了解各种栖息地中的氧化EET，包括海洋和陆地地下环境以及电子源减少的工程环境。从应用和生物技术的角度来看，这项工作的结果将提高评估遗传易处理生物体中微生物-电极相互作用的能力，并可能为电化学活性生物体的工业应用提供信息，如清洁能源发电，废水处理，该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值评估的支持和更广泛的影响审查标准。