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

AbstractIntellectual Merit.沉积物中的微生物群落将有机物再循环为沉积物柱中的无机结构单元。然而，在深埋的沉积物中，有机物的热裂解起着额外的、但类似的作用。在瓜伊马斯盆地，生物介导和热分解过程同时发生，产生了有机物分解产物的复杂混合物。 在这个项目中，PI将研究瓜伊马斯盆地沉积物中生物介导的甲烷生成和乙酸生成过程。 具体而言，PI将评估从活跃热液流体排放区和以对流冷却为主的侧翼区（例如热液流减少）收集的沉积物中的甲烷生成和乙酸生成速率。其他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（甲烷生成）或二氧化碳和氢气转化为乙酸（乙酸生成）。这项工作将阐明生物过程中产生甲烷和乙酸盐的有机丰富，热液影响的沉积物的瓜伊马斯盆地的作用。虽然产热过程被认为占该盆地的甲烷和乙酸盐生产的大部分，生物调解的可能性是强调了在各种栖息地的甲烷生产古生菌的存在。

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.