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？地壳。火山产生的气体和水岩反应的产物支持化学岩石自养微生物群落，这些微生物群落可能在海底普遍存在，并对深海和海底生物质生产作出重大贡献。在低温陆地环境中，微生物通常是通过代谢沿着化学梯度分离的。然而，迄今为止，深海地热环境中类似的生物沿地球化学梯度分布模式的研究还很少。在这样的研究中使用超嗜热菌是理想的，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它们所处环境的化学和温度。了解硫化物沉积物和弥漫性热液流体中不同类型的化化岩自养型超嗜热微生物的分布，将有助于了解可能生活在深层地下生物圈中的更大自养生物种群的分布。通过将实验室培养研究的代谢率与代谢反应的流体化学约束的详细现场测量相结合，本研究将向地表和地下喷口环境中微生物的定量建模迈出重要的一步。这些数据对于推进热液系统的全系统模型至关重要。本研究将解决RIDGE 2000科学计划中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)描述决定热液生物圈结构和范围的力量和联系；3)检查深海海底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)代表性不足群体的科学参与，4)在调查人员教授的课程中应用信息，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.