Collaborative Research: Modeling Hyperthermophile Growth in Deep-Sea Hydrothermal Sulfide Deposits and Diffuse Fluids

深海热液在地球的大片区域--S地壳中循环。火山产生的气体和水岩反应产生的产物支持化学自养微生物群落，这些微生物群落可能普遍存在于海底，并对深海和海底以下生物量的生产作出重大贡献。低温陆地环境中的微生物通常是通过沿化学梯度的新陈代谢来隔离的。然而，到目前为止，在深海地热环境中，类似的生物体沿地球化学梯度分布模式的证明还很少见。在这种研究中使用嗜热菌是理想的，因为这些微生物通常不存在于污染的背景海水中，而且它们的新陈代谢很可能反映其环境的化学和温度。了解不同类型的化学自养高温嗜热菌在硫化物沉积物和扩散的热液中的分布，将有助于深入了解可能生活在深层地下生物圈的更大规模的自养生物种群的分布。这项研究将通过将实验室培养研究的代谢率与对代谢反应的流体化学约束的详细现场测量相结合，朝着对表层和地下喷口环境中的微生物进行定量建模迈出重要的一步。这些数据将是推进水热系统全系统模型的关键。这项研究将涉及2000年山脊科学计划的7个基本目标中的3个：1)确定生物活动如何影响喷口化学；2)确定决定热液生物圈结构和范围的力量和联系；3)检查海底深层生物圈的性质和空间/时间范围。这项研究将包括五个方面的教育效益：1)研究生培训，2)本科生培训，3)代表不足的群体的科学参与，4)在调查人员教授的课程中应用信息，以及5)公众教育推广。

Deep-sea hydrothermal fluids circulate through vast portions of the earth?s crust. Volcanically derived gases and products from water-rock reactions support chemolithoautotrophic microbial communities that might be pervasive within the subseafloor and contribute significantly to deep-ocean and subseafloor biomass production. Microorganisms in low-temperature terrestrial environments are commonly segregated by metabolism along chemical gradients. However, demonstration of a similar distribution pattern of organisms along geochemical gradients in deep-sea geothermal environments to date has been rare. The use of hyperthermophiles for such a study is ideal since these organisms are generally not found in contaminating background seawater and since their metabolisms likely reflect the chemistry and temperature of their environment. Understanding the distribution of different types of chemolithoautotrophic hyperthermophiles in sulfide deposits and diffuse hydrothermal fluids will provide insight into the distribution of much larger populations of autotrophic organisms that may be living in the deep subsurface biosphere. This study will take an important step towards quantitative modeling of microbes in surface and subsurface vent environments by combining metabolic rates from laboratory culture studies with detailed field measurements of fluid chemistry constraints on metabolic reactions. The data will be critical to advancing whole-system models of hydrothermal systems. This study will address 3 of the 7 fundamental goals in the RIDGE 2000 Science Plan: 1) determining how biological activity affects vent chemistry, 2) characterizing the forces and linkages that determine the structure and extent of the hydrothermal biosphere, and 3) examination of the nature and space/time extent of the deep subseafloor biosphere. This study will include educational benefits in five areas: 1) graduate student training, 2) undergraduate student training, 3) scientific involvement of underrepresented groups, 4) application of information in courses taught by the investigators, and 5) public education outreach.