Evolution of Hydrogen-Based Microbial Communities in Deep Hydrothermal Aquifers

深层热液含水层中氢基微生物群落的演化

• 批准号: 0310606
• 负责人: Ronald Benner
• 金额: $ 10万
• 依托单位: University South Carolina Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-15 至 2005-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0310606&HistoricalAwards=false
• 关键词: Evolution; Hydrogen; Based; Microbial; Communities

The hydrothermal systems underlying the Snake River plain in Idaho present an opportunity to directly observe how microbial communities in deep subsurface hydrothermal systems change over time. The Snake River plain was formed as the North American plate has moved west over the Yellowstone Hotspot producing a time-transgressive series of volcanic fields and associated hydrothermal systems that range in age from the 2.0 million year old (Ma) Yellowstone volcanic field to the 16.1 Ma McDermitt volcanic field. Recent studies show the presence of a predominantly autotrophic, hydrogen-based microbial community at Lidy Hot Spring, associated with the 6.6 Ma Heise volcanic field. Preliminary studies suggest the presence of heterotrophic microorganisms in spring waters associated with older volcanic fields on the Snake River plain. It is proposed to systematically characterize changes in the microbial ecology and organic geochemistry of progressively older hydrothermal systems underlying the Snake River plain of Idaho. Understanding how autotrophic, hydrogen-based microbial communities in subsurface hydrothermal systems change over time, and understanding the accompanying changes in the reactivity and composition of organic matter in spring waters could yield insight to understanding the progression of life on the early Earth. Specifically, the relative proportion of Archaea and Bacteria present in spring waters will be determined, and the proportion of Bacteria capable of specific types of heterotrophic metabolism (i.e. sulfate-, iron- and nitrate reduction) will be assessed with quantitative PCR using primer sets specific for appropriate phylogenetic or functional genes. Parallel to this effort, the chemical and isotopic composition of dissolved organic matter (DOM) in the spring waters will be documented to assess changes in the bioavailability of substrates and to determine how this material reflects the composition of the resident microflora. The apparent transition from autotrophic to heterotrophic microbial communities provides an opportunity to investigate the roles of specific biological processes in the diagenesis of DOM and the production of refractory organic matter that is preserved in the environment. These data will be used to describe the variability and ecological progression of deep hydrothermal systems over a timeframe of approximately ten million years.

爱达荷州蛇河平原下的水热系统提供了一个直接观察深层地下热液系统中的微生物群落如何随时间变化的机会。蛇河平原是在北美板块在黄石热点上向西移动时形成的，产生了一系列随时间推移的火山田和相关的热液系统，年龄从200万年前的黄石火山场到16.1 Ma的麦克德米特火山场不等。最近的研究表明，利迪温泉存在一个以自养为主的氢基微生物群落，与6.6 Ma Heise火山田有关。初步研究表明，与蛇河平原上较老的火山田有关的泉水中存在异养微生物。建议系统地描述爱达荷州斯内克河平原下逐渐古老的热液系统的微生物生态和有机地球化学的变化。了解地下热液系统中以氢为基础的自养微生物群落是如何随着时间的推移而变化的，并了解泉水中有机物的反应性和组成的随之而来的变化，可以为理解地球早期生命的演化提供洞察力。具体而言，将确定泉水中存在的古生菌和细菌的相对比例，并将使用针对适当的系统发育或功能基因的特定引物集，通过定量聚合酶链式反应来评估能够进行特定类型异养代谢(即硫酸盐、铁和硝酸盐还原)的细菌的比例。在这项工作的同时，将记录泉水中溶解有机物(DOM)的化学和同位素组成，以评估基质生物有效性的变化，并确定这种材料如何反映常驻微生物区系的组成。从自养微生物群落到异养微生物群落的明显转变为研究特定生物过程在DOM成岩作用和环境中保存的难降解有机物生产中的作用提供了机会。这些数据将被用来描述深部热液系统在大约一千万年的时间范围内的变异性和生态进程。