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: 0452333
• 负责人: Stefan Sievert
• 金额: $ 81.79万
• 依托单位: Woods Hole Oceanographic Institution
• 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=0452333&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在生物学上具有深远的影响，并可能对各种生物地球化学过程产生重大影响。流经洋壳内裂隙和孔隙的热液流体为海底生物群落提供了潜在的丰富环境。最近发表的几项关于微生物喷发的观察指出，海底下生物圈的存在可能对这些热液系统的生产力有很大贡献：所谓的暴风雪或吹雪器喷口(例如，东太平洋隆起9度)的大量排放释放出大量白色絮状物质，这些物质堆积成5厘米厚的垫子。自那以后，这种材料被鉴定为丝状硫，由弧菌属的新微生物产生。PIS计划对这些丝状-S产生菌的丰度、分布和多样性进行综合的微生物学和地球化学研究，并在9°N EPR评估它们的生态作用。以前的观测和观测到地下生物量产出的喷发事件的可能性很高，这意味着这个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)形成丝状S的微生物的主要栖息地是浅的次表层，即次表层的一部分，其特征是热液与海水的活跃混合，而吹雪机喷口代表了该持久生物圈的快照样本。2)与硫化念珠菌相关的表观蛋白细菌通过还原的TCA循环完成了地下很大一部分CO2固定，这对初级生产力的估计和稳定碳同位素测量的解释具有重要意义。3)形成丝状的生物-S产生独特的地球化学标志(生物标志物、同位素)，并被沉积并成为地质记录的一部分。该项目将涉及：利用一种新的未受污染的就地微生物取样装置在不同的喷口生境进行取样；部署和回收装置，为量化微生物就地定殖提供新的表面；进行船上培养以评估功能；采用分子方法评估与环境条件有关的微生物群落的组成；进行稳定同位素和放射性示踪剂研究，以查明海底下自养微生物并测量其固定二氧化碳的速率；进行脂类生物标记物研究，以独立评估该系统中微生物的多样性和相对丰度。大量有机碳、特定脂类生物标志物和溶解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使用的固碳生理和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。预期成果将纳入各研究所实验室或各机构现有的课程和网页中。该项目将支持对一名研究生进行新兴地球生物学领域的培训，并鼓励少数群体和女性学生参与这些工作。通过潜水和发现项目，PI还将以中学生(6-8年级)和普通公众为目标。将创建一个BIOLIPID网站，向研究人员和更广泛的社区传播关于这一项目和几个密切相关项目的成果。