Microbial carbon and sulfur cycling in the hydrothermally altered sediments of Guaymas Basin

虽然海洋沉积物中的微生物群落通常由水柱中有机物的沉积维持，但瓜伊马斯盆地热液沉积物为微生物利用和转化深埋海洋有机质中热释放的微生物底物提供了一个模式系统。作为一个工作假说，生理上不同的、分层的微生物群落迫使地热产生的底物通过厌氧代谢和自养固碳的双重“微生物挑战”，有机质的最终厌氧降解由产甲烷和甲烷氧化的古菌、硫酸盐还原细菌和古菌以及可能由上层沉积物中的新的地下古菌种群执行，而无机和有机再矿化产物被沉积物表面的硫氧化Beggiatoa垫子同化。该项目将提供以下方面的定量了解：瓜伊马斯系统密集和高度活跃的底栖生物种群如何利用和循环源自地下的有机和无机碳和硫，地球化学控制如何影响群落结构，以及全球普遍存在的未培养的地下古生菌和细菌如何在其沉积物栖息地中茁壮成长。为了分析生热碳源和碳汇的复杂相互作用，以及未培养的微生物种群在这些过程中的作用，将采用地球化学和分子生物学方法。将对微生物群落组成和活性模式进行定量分析。将测量水热活动沉积物场地的碳底物分布和微生物过程速率(硫酸盐还原、甲烷生成、甲烷氧化)，并将其与微生物种群的变化相关联。瓜伊马斯盆地的喷口可以作为微生物和地质碳硫循环之间关键联系的模式系统，并对微生物作为海洋环境和海洋次表层化学催化剂的作用提供了新的认识。为了挖掘瓜伊马斯在海洋科学中教授生物-地质联系的巨大潜力，该项目与生物多样性教育和公共外联(BEPO)小组及其在伍兹霍尔海洋生物实验室的Micros*COPE资源发起了外联项目，该实验室也针对非英语少数族裔社区的科学教育工作者和学校。此外，瓜伊马斯项目将加强本科生和研究生的教学，并为研究生和本科生提供实践研究机会。

While microbial communities in marine sediments are generally sustained by sedimentation of organic matter from the water column, the Guaymas Basin hydrothermal sediments provide a model system for the microbial utilization and transformation of thermally released microbial substrates from deeply buried marine organic matter. As a working hypothesis, the physiologically distinct, layered microbial communities force the geothermally produced substrates through a double "microbial gauntlet" of anaerobic metabolism and autotrophic carbon fixation, where terminal anaerobic degradation of organic matter is performed by methanogenic and methane-oxidizing archaea, by sulfate-reducing bacteria and archaea, and potentially by novel subsurface archaeal populations within the upper sediments, while inorganic and organic remineralization products are assimilated by sulfur-oxidizing Beggiatoa mats at the sediment surface. This project will provide a quantitative understanding of how the dense and highly active benthic microbial populations of the Guaymas system utilize and recycle organic and inorganic carbon and sulfur of subsurface origin, how geochemical controls affect the community structure, and how uncultured, globally occurring subsurface archaea and bacteria thrive in their sediment habitat. To analyze the complex interplay of thermogenic and biogenic carbon sources and sinks, and the role of uncultured microbial populations in these processes, geochemical and molecular-biological approaches will be undertaken. The microbial community composition and activity patterns will be analyzed quantitatively. Carbon substrate profiles and microbial process rates (sulfate reduction, methanogenesis, methane oxidation) across hydrothermally active sediment sites will be measured and correlated to variations in microbial populations. The Guaymas Basin vents can serve as a model system for key linkages of the microbial and geological carbon and sulfur cycles, and shed new light on the roles of microorganisms as chemical catalysts of the marine environment and the marine subsurface. To tap into the great potential of Guaymas for teaching of biological-geological linkages in marine science, this project has initiated outreach projects with the Biodiversity Education and Public Outreach (BEPO) team and its Micros*cope resource at the Marine Biological Laboratory in Woods Hole, which also targets science educators and schools of non-english speaking minority communities. In addition, the Guaymas project will enhance undergraduate and graduate teaching, and provide hands-on research opportunities for graduate and undergraduate students.