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

深海热液在地球的大部分地区循环？的外壳。火山产生的气体和水岩反应产物支持化能自养微生物群落，这些微生物群落可能遍布海底以下，并对深海和海底以下生物质生产作出重大贡献。低温陆地环境中的微生物通常通过代谢沿着化学梯度分离。然而，迄今为止，在深海地热环境中，生物体沿着地球化学梯度的类似分布模式的证明很少。使用超嗜热菌进行这种研究是理想的，因为这些生物通常不会在污染的背景海水中发现，而且它们的代谢可能反映了其环境的化学和温度。了解硫化物矿床和扩散热液流体中不同类型的化能自养超嗜热菌的分布情况，将有助于深入了解可能生活在深层地下生物圈中的更大数量的自养生物的分布情况。这项研究将采取一个重要步骤，定量模拟微生物在地表和地下喷口环境相结合的代谢率从实验室培养研究与详细的现场测量流体化学约束代谢反应。这些数据对于推进热液系统的全系统模型至关重要。这项研究将涉及海脊2000年科学计划7个基本目标中的3个：⑴确定生物活动如何影响喷口化学; ⑵确定决定热液生物圈结构和范围的各种力量和联系的特征; ⑶审查深海海底下生物圈的性质和时空范围。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）代表性不足的群体的科学参与，4）调查人员教授的课程中的信息应用，以及5）公共教育推广。

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.