Characterizing the contribution of bacteria from the SUP05 clade to autotrophic and heterotrophic carbon cycling across ocean gradients

海洋里的生命是由各种各样的微生物群落主导的，它们以藻类的残骸为燃料。不同微生物群落成员的相对活动可以决定海洋捕获温室气体、营养物质回收和食物生产的程度。目前，我们在量化这些过程之间的平衡的能力上存在一个关键的差距。我们理解微生物玩家的一个主要障碍是我们无法在实验室中培养甚至是最丰富的生物体并研究它们的生理学。随着最近对海洋中常见的三种细菌的培养，我们有可能在了解它们对海洋过程的贡献以及它们在未来如何变化方面取得重大进展。该项目将在培养中描述这三种细菌的特征，以开发工具来确定它们在野外的活动。由于这些细菌在低氧环境中很常见，因此这项工作特别适合解决微生物群落对缺氧水的反应。该项目将通过与华盛顿大学研究生综合教育和研究培训计划、气候变化计划和华盛顿大学教育推广计划合作，在一个重要的研究领域培养研究生和本科生。研究结果将在国家和国际会议上提出，并通过出版物提出。所有数据将通过生物和化学海洋数据管理办公室（BCO-DMO）免费提供。自养和异养之间的平衡决定了海洋碳汇的大小以及食物链中可用的物质和能量的通量。尽管努力确定主要细菌和古细菌谱系对碳通量的贡献，但对决定控制碳通量的潜在代谢的环境条件知之甚少。硫氧化γ -变形菌的SUP05分支的成员在黑暗的海洋中大量存在，并且可以控制扩展的缺氧和缺氧区域，在那里它们具有产生和消耗有机物的潜力。最近对SUP05支系3个代表的培养显示了支系内惊人的代谢多样性。这些分离物提供了一个前所未有的机会来阐明碳限制、能量限制和氧张力对一组关键海洋细菌生产和消耗有机物的影响。这里提出的工作将1)确定在不同环境条件下不同培养代表的自养碳固定和异养有机质同化之间的平衡2)确定促进自养的反应动力学3)沿着不同环境条件诱导的自养和异养生产梯度表征生物标志物4)在野外检测这些分子标记以及细胞丰度以确定在横过北太平洋氧最低带的野外站点上，自养、异养、硫氧化和反硝化对SUP05代谢的贡献。该项目将促进对SUP05的理解，SUP05是中上层生物元素循环的驱动因素，中上层是地球上最大的栖息地之一，正在经历巨大的气候驱动变化，包括氧气最小带的扩大。

Life in the ocean is dominated by diverse communities of microorganisms that are fueled by the remains of algae. The relative activity of different microbial community members can determine the extent of greenhouse gas capture, recycling of nutrients and food production by the ocean. Currently, there is a critical gap in our ability to quantify the balance between these processes. A major roadblock in our ability to understand the microbial players is our inability to grow even the most abundant organisms in the lab and study their physiology. With the recent cultivation of three bacteria common to the ocean, the possibility exists to make major advances in our understanding of their contribution to ocean processes and how they might change in the future. This project will characterize these three bacteria in culture to develop tools to determine their activities in the field. Because these bacteria are common in low oxygen environments, this work is particularly well poised to address how microbial communities respond to oxygen-depleted waters. This project will train graduate and undergraduate students in an important research area through collaboration with the University of Washington Integrative Graduate Education and Research Traineeship program, the Program for Climate change and the University of Washington's Educational Outreach Program. Results will be presented at national and international meetings and through publication. All data will be freely available through the Biological and Chemical Oceanographic Data Management Office (BCO-DMO).The balance between autotrophy and heterotrophy determines the size of the ocean's carbon sink and the flux of material and energy available to food chains. Despite efforts to identify the contributions of major bacterial and archaeal lineages to carbon fluxes, little is known about the environmental conditions that determine the underlying metabolisms controlling carbon flux. Members of the SUP05 clade of sulfur oxidizing gamma-proteobacteria are abundant in the dark ocean and can dominate expanding suboxic and anoxic zones, where they have the potential to both produce and consume organic matter. The recent cultivation of 3 representatives from the SUP05 clade has revealed striking metabolic diversity within the clade. These isolates represent an unprecedented opportunity to elucidate the effects of carbon limitation, energy limitation and oxygen tension on the production and consumption of organic matter by a critical group of marine bacteria. The work proposed here would 1) determine the balance between autotrophic carbon fixation and heterotrophic organic matter assimilation in diverse cultured representatives under varying environmental conditions 2) determine the kinetics of reactions fueling autotrophy 3) characterize biomarkers along gradients of autotrophic and heterotrophic production induced by varying environmental conditions and 4) detect these molecular markers in the field along with cell abundances to determine the contribution of autotrophy, heterotrophy, sulfur oxidation and denitrification to SUP05 metabolism in a field site that transects an oxygen minimum zone in the North Pacific Ocean. This project will advance understanding of SUP05, a biological driver of elemental cycling in the mesopelagic, one of the largest habitats on earth and one that is experiencing large climate driven changes, including expansion of oxygen minimum zones.