Collaborative Research: Adaptive response of microbial communities and Fe biomineralization pathways to anaerobic redox cycling of Fe and N in sediments

EAR-0525510/EAR-0525069合作研究：微生物群落和铁的生物矿化途径对沉积物中铁和氮的厌氧氧化还原循环的适应性响应本项目将探索厌氧沉积物中微生物催化的铁(Fe)氧化还原循环的机制。铁是地壳中第四丰富的元素，其氧化还原循环对水生和陆地生态系统中各种有机和无机化合物的行为产生了强烈的影响。因此，近地表环境中与铁氧化还原循环相关的微生物群落的结构和功能是环境微生物学和生物地球化学的重要课题。该项目涉及与现代底土和浅层地下水环境中的铁氧化还原循环和生物矿化有关的微生物群落结构和生理学的几个独特方面。这些环境是天然和人为物质(如城市和农业系统的径流)的主要接受者，微生物在地下生物地球化学过程中发挥关键作用。拟议的研究将探索微生物种群和群落从铁氧化还原循环中获取能量的新策略，并将检查此类活动的矿物学特征。实验反应运输系统将被用来模拟自然的地下环境，在这种环境中，电子供体和受体的输入的时间变化预计将强烈影响微生物群落的发展和铁的生物矿化模式。实验系统将支持来自淡水湿地表层沉积物或大西洋沿岸浅海平原含水层沉积物的微生物群落。我们假设，从铁和氮氧化还原相互作用中获得的能量将导致微生物种群和/或群落的发展，这些微生物种群和/或群落专门适应于利用氧化还原振荡期间可用的能量。此外，我们预计，在稳定的氧化还原条件下，受氧化还原波动影响的沉积物的铁矿物学将向一套结晶度相对较低、活性较高的亚稳矿物演化。本研究将开发的反应器系统代表了新的研究技术，用于检查微生物生理学、群落结构、生物地球化学反应动力学和铁生物矿化之间的联系。从这些模型系统获得的地球微生物和生物地球化学信息将被纳入基于微生物能量学的数值模拟框架中，这将使我们的实验研究结果能够转移到各种地表和地下沉积环境。该项目将培训两名博士生，学习多学科生物地球化学研究方法以及沉积物中生物地球化学过程和微生物种群动力学的数值模拟技术。一名本科生实习生将在伊利诺伊州大学参与微生物培养和分离。华盛顿大学的博士生将参加教师暑期研究体验(RET)研究员的培训。RET研究员将进行原创性研究，并前往科学会议，在项目的最后两年展示他或她的研究。这位密歇根大学的博士生还将参加由国家科学基金会赞助的密歇根大学研究、培训和学习一体化中心(CIRTL)计划，该计划提供课程和协调实习计划，为更广泛的社区提供实践经验。除了这些活动外，印第安纳大学还将与富布赖特科学与技术学院(FAST)开展一项新的合作，旨在提高公众对环境微生物学重要性的理解。我们将与FAST合作开发演讲模块，由FAST成员在美国各地选定的地点进行演讲。一般性演讲将涵盖公众当前感兴趣的主题，如细菌在温室气体新陈代谢中的作用、污染物的降解以及土壤和沉积物中的养分循环(特别是N和Fe)。

EAR-0525510/EAR-0525069Collaborative Research: Adaptive response of microbial communities and Fe biomineralization pathways to anaerobic redox cycling of Fe and N in sedimentsThis project will explore mechanisms of microbially-catalyzed iron (Fe) redox cycling in anaerobic sediments. Iron is the fourth most abundant element in the Earth's crust, and its redox cycling exerts a strong influence on the behavior of various organic and inorganic compounds in both aquatic and terrestrial ecosystems. The structure and function of microbial communities associated with Fe redox cycling in near-surface environments is therefore an important topic in environmental microbiology and biogeochemistry. This project addresses several unique aspects of microbial community structure and physiology related to Fe redox cycling and biomineralization in modern subsoils and shallow groundwater environments. Such environments are primary receptors of both natural and anthropogenic materials (e.g. run-off from urban and agricultural systems), and microorganisms play a key role in subsurface biogeochemical processes.The proposed research will explore novel strategies that microbial populations and communities may utilize to derive energy from Fe redox cycling, and will examine the mineralogical signatures of such activities. Experimental reactive transport systems will be used to mimic natural subsurface environments in which temporal variations in the input of electron donors and acceptors are expected to strongly influence microbial community development and patterns of Fe biomineralization. The experimental systems will support microbial communities from either a freshwater wetland surface sediment or shallow Atlantic Coastal plain aquifer sediment. We hypothesize that the energy available from Fe and nitrogen redox interactions will lead to the development of microbial populations and/or communities specifically adapted to take advantage of the energy available during redox oscillations. In addition, we anticipate that the Fe mineralogy of sediments subject to redox fluctuations will evolve toward a suite of metastable minerals of relative low crystallinity and high reactivity relative to those in sediments under stable redox conditions. The reactor systems to be developed in this study represent novel research techniques for examining linkages between microbial physiology, community structure, biogeochemical reaction dynamics, and Fe biomineralization. The geomicrobiological and biogeochemical information gained from these model systems will be incorporated into a microbial energetics-based numerical simulation framework that will allow the results of our experimental studies to be transferred to a variety of surface and subsurface sedimentary environments.The project will train two Ph.D. students in multidisciplinary biogeochemical research methodologies as well as techniques for numerical simulation of biogeochemical processes and microbial population dynamics in sediments. An undergraduate intern will participate in microbial culturing and isolation at IU. The UW Ph.D. student will participate in the training of a summer Research Experience for Teachers (RET) fellow. The RET fellow will conduct original research, and travel to scientific meetings to present his or her research during the last two years of the project. The UW Ph.D. student will also participate in the NSF-sponsored Center for Integration of Research, Training, and Learning (CIRTL) program at UW, which offers courses and coordinates internship programs that provide practical experience in bringing science to the broader community. In addition to these activities, IU will undertake a novel collaboration with the Fulbright Academy of Science and Technology (FAST) aimed at increasing public understanding about the importance of environmental microbiology. We will work with FAST to develop presentation modules that will be offered by FAST members at selected locations around the U.S. The general presentations will cover topics of current interest to the public such as the role of bacteria in the metabolism of greenhouse gases, degradation of pollutants, and nutrient cycling (specifically N and Fe) in soils and sediments.