RAPID: Biologically-mediated methanogenesis and acetogenesis in the hydrothermally altered sediments of the Guaymas Basin

AbstractIntellectual优点。沉积物微生物群落在整个沉积物柱中将有机物循环为无机构件。然而，在深埋的沉积物中，有机质的热裂解起着额外但类似的作用。在瓜伊马斯盆地，生物介导和热分解过程共同发生，形成了有机物质分解产物的复杂混合物。在这个项目中，PI将研究Guaymas盆地沉积物中生物介导的甲烷生成和丙酮生成过程。具体而言，pi将评估从活跃热液喷口区域和以对流冷却为主的侧翼区域收集的沉积物中甲烷生成和丙酮生成的速率（例如热液流动减少）。额外的实验将量化温度和压力对这些重要的生物介导过程的影响，这些过程将二氧化碳和有机碳转化为甲烷（产甲烷）或二氧化碳和氢转化为乙酸（产丙酮）。更广泛的影响。这项工作将阐明生物过程在Guaymas盆地富有机质、受热液影响的沉积物中产生甲烷和醋酸盐的作用。虽然热生成过程被认为是该盆地甲烷和醋酸盐生产的主要原因，但在各种栖息地中存在的产甲烷古细菌强调了生物中介的可能性。

AbstractIntellectual Merit. Sediment microbial communities recycle organic matter to inorganic building blocks throughout the sediment column. In deeply buried sediments, however, thermal cracking of organic matter plays an additional, but similar role. In the Guaymas basin, biologically-mediated and thermal decomposition processes co-occur, creating a complex mixture of organic matter breakdown products. In this project, the PI's will examine the processes of biologically-mediated methanogenesis and acetogenesis in Guaymas Basin sediments. Specifically, the PIs will evaluate rates of methanogenesis and acetogenesis in sediments collected from areas of active hydrothermal fluid venting and from flanking areas dominated by convective cooling (e.g. reduced hydrothermal flow). Additional experiments will quantify the impact of temperature and pressure on these important biologically-mediated processes that transform carbon dioxide and organic carbon into methane (methanogenesis) or carbon dioxide and hydrogen into acetate (acetogenesis).Broader Impact. This work will clarify the role of biological processes in producing methane and acetate in the organic rich, hydrothermally influenced sediments of the Guaymas Basin. While thermogenic processes are assumed to account for the majority of methane and acetate production in this Basin, the possibility of biological-mediation is underscored by the presence of methane producing archaea in a variety of habitats.