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

学术成就：厌氧微生物过程介导缺氧土壤、沉积物和水生系统中的有机碳矿化。麦克默多干谷（MCM）的湖泊常年被冰雪覆盖，是这片极度干旱的极地沙漠中生命的主要避难所。拟议研究的重点是厌氧微生物介导的碳循环在底层水和沉积物的两个地球化学对比干谷湖泊，弗里克塞尔（FRX）和万达（货车）。以往的研究和初步数据表明，这些湖泊的硫酸盐还原和甲烷生成的关键厌氧过程是不同的。在货车中，厌氧代谢以硫酸盐还原为主，而在FRX中甲烷生成占主导地位。该研究计划将详细研究一个全球相关的生物地球化学过程，甲烷的厌氧氧化（AOM），这几乎可以肯定是由FRX中的一种新的代谢机制支持的;万达湖AOM的潜力尚不清楚。该研究计划将解决以下首要问题：什么因素控制缺氧和高度稳定的极地湖泊沃茨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负责AOM，哪些电子受体支持AOM？具体而言，本工作将确定（1）缺氧底层沃茨和沉积物中厌氧碳硫循环的速率和/或机制;（2）硫酸盐在FRX和货车中驱动厌氧碳硫循环的作用;（3）缺氧硫酸盐耗尽的FRX底层沃茨和沉积物中AOM的机制;（4）货车富硫酸盐底沃茨和沉积物中AOM的存在及其机制;（5）这些湖泊中参与AOM和其他甲烷、硫循环过程的微生物的同一性和多样性。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。PI将为学生和工作人员提供一个专注的，动手的微生物学和微生物学研究经验，同时推进我们对常年冰封湖泊中微生物学和微生物化学的理解。将通过与PI主页和MCM LTER网站链接的专用网站、新闻稿、在国家和国际会议上的介绍以及同行评审的出版物来完成数据分发和推广。

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