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

[摘要]智力功绩。沉积物微生物群落在整个沉淀柱中将有机质循环为无机构件。然而，在埋藏较深的沉积物中，有机质的热裂解起着额外的、但类似的作用。在瓜伊马斯盆地，生物调节和热分解过程同时发生，产生了有机质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的生物介导性甲烷生成和乙酸化过程。具体地说，PIS将评估从活跃的热液喷发区域和从以对流冷却为主的侧翼区域(例如减少的热液流动)收集的沉积物中的产甲烷和产乙酸率。其他实验将量化温度和压力对这些重要的生物中介过程的影响，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醋酸酯(乙酸化)。这项工作将阐明生物过程在瓜伊马斯盆地有机丰富、受水热影响的沉积物中产生甲烷和醋酸盐的作用。虽然生热作用被认为是该盆地甲烷和醋酸盐产生的主要原因，但各种生境中产生甲烷的古生菌的存在突显了生物调解的可能性。

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.