Collaborative Research: Microbially Mediated Anaerobic Carbon Cycling in Limnologically Contrasting Perennially Ice-Covered Antarctic Lakes

智力优势：厌氧微生物过程在缺氧土壤、沉积物和水生系统中调节有机碳矿化。麦克默多干谷(MCM)的湖泊常年被冰覆盖，是这片极度干旱的极地沙漠中生命的主要避难所。拟议的研究重点是两个在地球化学上不同的干谷湖泊Fryxell(FRX)和Vanda(VAN)的底层水和沉积物中的厌氧微生物介导的碳循环。以往的研究和初步数据表明，这些湖泊硫酸盐还原和产甲烷的关键厌氧过程是不同的。在VAN中，厌氧代谢以硫酸盐还原为主，而在FRX中以产甲烷为主。该研究计划将详细研究全球相关的生物地球化学过程--甲烷厌氧氧化(AOM)，这几乎肯定得到FRX代谢新机制的支持；万达湖中AOM的潜力尚不清楚。该研究计划将解决以下主要问题：什么因素控制着缺氧和高度稳定的极地湖泊水域和沉积物中的终端碳代谢？在这些独特的湖泊中，哪些新的微生物群落对AOM负有责任，哪些电子受体(S)支持AOM？具体地说，这项工作将确定(1)缺氧底层水和沉积物中厌氧碳和硫循环的速率和/或机制；(2)硫酸盐在FRX和VAN中驱动厌氧碳/硫循环的作用；(3)FRX缺氧硫酸盐枯竭的底层水和沉积物中AOM的机制；(4)VAN富含硫酸盐的底层水和沉积物中AOM的存在和机制；(5)参与AOM和这些湖泊中其他甲烷和硫循环过程的微生物的特性和多样性。更广泛的影响：该项目将雇用博士后、研究生和本科生，并将补充现有的NSF资助的项目、MCM长期生态研究(LTER)和微生物观测站(MO)项目。PIS将为学生和教职员工提供集中的、实践的生物地球化学和微生物学研究体验，同时促进我们对常年结冰湖泊中的微生物学和生物地球化学的理解。数据分发和外联工作将通过一个专门的网站来完成，该网站链接到国际和平协会的主页和长期监测机制的网站、新闻稿、在国家和国际会议上的介绍以及同行评议的出版物

Intellectual Merit: Anaerobic microbial processes mediate organic carbon mineralization in anoxic soils, sediments, and aquatic systems. The lakes of the McMurdo Dry Valleys (MCM) are perennially ice-covered and are the primary refuge for life in this hyperarid polar desert. The focus of the proposed research is on anaerobic microbially mediated carbon cycling in the bottom water and sediments of two geochemically contrasting Dry Valley lakes, Fryxell (FRX) and Vanda (VAN). Previous studies and preliminary data indicate that the key anaerobic processes of sulfate reduction and methanogenesis are distinct these lakes. In VAN, anaerobic metabolism is dominated by sulfate reduction while methanogenesis dominates in FRX. The research plan will study in detail a globally relevant biogeochemical process, the anaerobic oxidation of methane (AOM), which is almost certainly supported by a metabolically novel mechanism in FRX; the potential for AOM in Lake Vanda is unknown. The research program will address the following overarching questions: What factors control terminal carbon metabolism in anoxic and highly stable polar lake waters and sediments? What novel microbial communities are responsible for AOM and which electron acceptor(s) support AOM in these unique lakes? Specifically, the work will determine (1) The rates and/or mechanisms of anaerobic carbon and sulfur cycling in anoxic bottom waters and sediments; (2) The role of sulfate in driving anaerobic carbon/sulfur cycling in FRX and VAN; (3) The mechanism of AOM in the anoxic sulfate-depleted bottom waters and sediments of FRX; (4) The existence and mechanism of AOM in the sulfate-rich bottom waters and sediments of VAN; (5) The identity and diversity of the microorganisms involved in AOM and other methane- and sulfur-cycling processes in these lakes. Broader Impacts: The project will employ post-doctoral, graduate, and undergraduate students, and will complement existing NSF-funded projects, the MCM Long Term Ecological Research (LTER) and Microbial Observatory (MO) projects. The PIs will provide a focused, hands-on research experience in biogeochemistry and microbiology to students and staff while simultaneously advancing our understanding of microbiology and biogeochemistry in perennially ice covered lakes. Data distribution and outreach will be accomplished via a dedicated web site linked to the PI's home page and to the MCM LTER web site, press releases, presentations at national and international conferences, and publication in peer-reviewed