COLLABORATIVE RESEARCH: Microbiology and Biogeochemistry of Autotrophic Microbes in the Subsurface at Hydrothermal Vents: Filamentous-Sulfur Producing Bacteria

合作研究：热液喷口地下自养微生物的微生物学和生物地球化学：丝状产硫细菌

• 批准号: 0452410
• 负责人: Roger Summons
• 金额: $ 13.08万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-01 至 2009-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0452410&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Microbiology; Biogeochemistry; Autotrophic

The recent discovery of microbial populations beneath the deep ocean floor has far reaching implications in biology and has a potentially strong influence on a variety of biogeochemical processes. Hydrothermal fluid flowing through cracks and pores within the oceanic crust provides a potentially rich environment for subseafloor biological communities. Several recently published observations of .microbial eruptions point to the existence of a subseafloor biosphere that might contribute considerably to the productivity of these hydrothermal systems: Extensive discharges from so-called blizzard or snowblower vents (e.g., 9 deg N East pacific Rise) released large amounts of white flocculent material which accumulated into mats of 5 cm thickness. This material has since been identified as filamentous sulfur produced by novel microbes of the genus Arcobacter. The PIs plan an integrated microbiological and geochemical study of the abundance, distribution, and diversity of these filamentous-S producing microbes, and assessment of their ecological role at 9deg N EPR. Previous observations and the high likelihood for observing eruptive events with output of subsurface biomass mean that this site is well suited to address these questions. The proposed studies will test the following general hypotheses: 1) The prime habitat of filamentous-S-forming microbes is the shallow subsurface, i.e., that part of the subsurface characterized by the active mixing of hydrothermal fluid with seawater, and snowblower vents represent a snapshot sample of that persistent biosphere. 2) A significant portion of CO2-fixation in the subsurface is carried out by epsilon proteobacteria related to Candidatus Arcobacter sulfidicus by means of the reductive TCA cycle, which has significant implications for primary production estimates and interpretation of stable carbon isotope measurements. 3) The organisms forming filamentous-S produce a distinctive geochemical signature (biomarker, isotope) that is deposited and becomes part of the geological record. The project will involve: sampling at various vent habitats with a new device for uncontaminated in situ microbial sampling; deployment and recovery of devices to provide new surfaces for quantifying in situ colonization by microbes; shipboard culturing to assess function; molecular methods to assess the composition of the microbial community in relation to environmental conditions; stable isotope and radiotracer studies to identify autotrophic subseafloor microorganisms and measure their rates of CO2-fixation; and lipid biomarker studies to provide an independent assessment of the diversity and relative abundances of microbes in this system. Stable isotope ratios of bulk organic carbon, specific lipid biomarkers and dissolved inorganic carbon will provide information on the carbon-fixation physiologies employed by specific types of vent microbes and the transfer of carbon within the system. The broader impacts of this project include establishment of an inter-disciplinary collaboration between two institutions in the field of geobiology. It is expected that results will be integrated into coursework and web pages existing either in the PI.s labs or at the respective institutions. The project will support training of one graduate student in the emerging field of geobiology and encourage participation of minority and female students in these roles. Through the Dive and Discover project, the PIs will also target middle-school students (Grades 6-8) and the general public. A BIOLIPID website will be created to disseminate results on this and several closely related projects to researchers and the wider community.

最近在深海海底发现的微生物种群对生物学具有深远的影响，并对各种生物地球化学过程具有潜在的强大影响。流经洋壳内裂缝和孔隙的热液流体为海底生物群落提供了潜在丰富的环境。最近发表的一些微生物喷发观测结果表明，海底生物圈的存在可能对这些热液系统的生产力做出重大贡献：所谓的暴风雪或吹雪机喷口（例如，北纬 9 度东太平洋海隆）的大量排放释放了大量的水。大量白色絮状物质堆积成 5 厘米厚的垫子。此后，这种材料被鉴定为由弓形杆菌属新型微生物产生的丝状硫。 PI 计划对这些丝状硫微生物的丰度、分布和多样性进行综合微生物学和地球化学研究，并评估它们在北纬 9 度 EPR 的生态作用。之前的观测结果以及观测到喷发事件并输出地下生物量的高可能性意味着该地点非常适合解决这些问题。拟议的研究将检验以下一般假设：1）丝状S形成微生物的主要栖息地是浅层地下，即以热液与海水主动混合为特征的地下部分，吹雪机通风口代表了该持久生物圈的快照样本。 2) 地下二氧化碳固定的很大一部分是由与硫化弓形杆菌相关的ε变形菌通过还原TCA循环进行的，这对初级生产估计和稳定碳同位素测量的解释具有重要意义。 3) 形成丝状-S的生物体产生独特的地球化学特征（生物标记、同位素），该特征被沉积并成为地质记录的一部分。该项目将包括： 使用一种新的未受污染的原位微生物采样装置在不同的喷口栖息地进行采样；部署和回收设备以提供新的表面来量化微生物的原位定殖；船上培养以评估功能；评估与环境条件相关的微生物群落组成的分子方法；稳定同位素和放射性示踪剂研究，以识别自养海底微生物并测量其二氧化碳固定率；和脂质生物标志物研究，以对该系统中微生物的多样性和相对丰度进行独立评估。大量有机碳、特定脂质生物标志物和溶解的无机碳的稳定同位素比率将提供有关特定类型的喷口微生物所采用的碳固定生理学以及系统内碳转移的信息。该项目的更广泛影响包括在地球生物学领域的两个机构之间建立跨学科合作。预计结果将被整合到 PI.s 实验室或各自机构现有的课程作业和网页中。该项目将支持在新兴的地球生物学领域培训一名研究生，并鼓励少数民族和女学生参与这些角色。通过“潜水和发现”项目，PI 还将针对中学生（6-8 年级）和公众。将创建一个 BIOLIPID 网站，向研究人员和更广泛的社区传播该项目以及几个密切相关项目的结果。