Environmental Hydrogenases in Geothermal Hotsprings

这个项目的总体目标和智力价值是描述和理解黄石地热生态系统中氢代谢的微生物组成、结构和代谢基础。黄石地热生态系统通常被认为是由硫代谢支持的。然而，最近的研究表明，群落依赖于氢代谢，并可能主导这个和其他地热生态系统。氢是宇宙中最丰富的元素，也是细菌和古细菌系统发育域中各种微生物能量代谢的基础。这种广泛的系统发育现象表明，氢代谢在生命进化的早期就出现了。尽管氢化酶无处不在且古老，但在以氢为主要能源的天然微生物群落中，人们对负责这种代谢的酶（氢化酶）的存在/缺失知之甚少。这项工作将集中于聚合酶链反应（PCR）扩增环境获得的DNA样本，以表征和分类负责铁、铁/铁和铁/镍氢化酶的功能基因的发生。一些样本将在黄石国家公园周围收集，并在实验室进行分析。这项拟议工作的更广泛的科学影响至少是两方面的。首先，如果在72摄氏度的光合作用极限以上，氢确实是生命的主要燃料，为什么会这样呢？例如，它是生命的进化根源吗？第二，利用氢分子作为电子供体的能力有多普遍，哪些酶对这种利用负责？这些问题的答案不仅与更好地理解高温生态系统有关，而且与如何通过加强对氢利用和/或产生的理解来利用这些过程来替代燃料的输送有关。此外，对黄石生态系统氢化酶功能基因的分析，将为潜在的生命化学提供新的视角。总体结果将与地球微生物学、高温微生物学、进化、应用科学和新兴的天体生物学领域有关。该项目将包括研究生培训机会。其他教育和推广活动将与黄石资源中心协调。

The overarching goal and the intellectual merit of this project is to describe and understand the microbial composition, structure, and metabolic underpinnings of hydrogen metabolism in the Yellowstone geothermal ecosystem. The Yellowstone geothermal ecosystem is generally considered to be supported by sulfur metabolism. However, recent work suggests that communities instead are dependent on hydrogen-metabolism and may dominate this and other geothermal ecosystems. Hydrogen is the most abundant element in the universe and the basis of diverse microbial energy metabolisms throughout the bacterial and archaeal phylogenetic domains. This wide phylogenetic occurrence suggests that hydrogen metabolism arose early in the evolution of life. Although ubiquitous and ancient, little is known about the presence/absence of the enzymes responsible for this metabolism (hydrogenase enzymes) in naturally occurring microbial communities that are supported by hydrogen as a primary energy source. The proposed work will focus on polymerase chain reaction (PCR) amplification of environmentally obtained DNA samples to characterize and classify the occurrence of the functional genes responsible for iron, iron/iron, and iron/nickel hydrogenase enzymes. Several samples will be collected around Yellowstone National Park and subjected to analysis in the lab.The broader scientific impact of the proposed work is at least two fold. First, if hydrogen is indeed the main fuel for life above the photosynthetic limit of 72 degrees centigrade, why is this? Is it an evolutionary root of life, for example? Second, how widespread is the ability to use molecular hydrogen as an electron donor, and what enzymes are responsible for that utilization? The answer to these questions has relevance not only for a greater understanding of high-temperature ecosystems, but how these processes can be harnessed for alternative fuel delivery through an enhanced understanding of hydrogen utilization and/or generation. In addition, the hydrogenase functional gene analysis of the Yellowstone ecosystem, will provide new perspectives on potential chemistries of life. The overall results will be relevant to geomicrobiology, high-temperature microbiology, evolution, applied science and to the emerging field of astrobiology. The project will include graduate student training opportunities. Other educational and outreach activities will be coordinated with the Yellowstone Center for Resources.