Collaborative Research: Geochemical Effects on the Functional Microbial Community Dynamics of Hydrothermal Deposits along the Eastern Lau Spreading Center

深海热液喷口存在极端的环境梯度，高温、低pH和还原流体与冷含氧海水混合。这导致大量微生物利用了丰富的微生态系统。从小亚基（16S） rRNA基因调查和许多地点喷口沉积物的定向富集培养中，多样性模式正在出现，表明地球化学过程，特别是那些影响流体pH值的过程，在调节微生物多样性和群落组成方面发挥着根本作用。本文通过对东劳扩散中心（ELSC）喷口场为期3年的研究，探讨了喷口地球化学与微生物群落动态的关系。之所以选择ELSC，是因为它提供了流体和岩石地球化学、扩张速度、岩浆/构造过程的大而系统的变化，并且在相对较短的397公里长度上靠近火山弧。因此，单个热泉田为深入探索与深海热液矿床的活跃形成有关的影响微生物群落多样性和关系的因素提供了极好的自然实验室。研究将在ELSC沿线3个地球化学性质不同的热液场进行。科学家们将记录每个地区与热液沉积物相关的微生物群落组成和多样性，以便与2009年和2005年获得的数据进行比较。在ELSC内，这些地球化学上不同的喷口区域非常接近，为研究喷口流体和沉积物地球化学对微生物群落结构和功能的影响以及与活动热液矿床相关的单个种群的具体作用提供了理想的机会。研究人员假设，考虑到极端的环境特征（例如，Mariner的低流体pH值和高铁），他们将看到基洛莫阿纳、ABE和Mariner喷口场之间宏基因组，特别是宏转录组的明显差异。具体目标是：1)连接ELSC沿线的地球化学和微生物动力学（从2005年到2013年）；2)利用宏基因组学和转录组学数据，探索调节ELSC沿线喷口田微生物群落功能作用的生物地球化学循环；3)利用宏基因组信息富集靶向新型热蛋白和嗜酸菌。活动热液金属硫化物矿床和流体样品将从沿ELSC的喷口区收集。条形码焦磷酸测序的古细菌和细菌的16S rRNA扩增子将获得超过80个样品。将模拟烟囱的地球化学环境，以确定原位地球化学条件。这些值将用于统计分析，以探索影响观察到的社区差异的因素。使用16S rRNA基因454 pyrotags结合地球化学表征，将选择特定样品进行宏基因组和亚转录组分析（每个位点1-3个）。分子信息将用于针对特定样品：(i)具有新的未分类多样性；（ii）有通风病谱系；（iii）有来自陆地系统的亲酸性亲属，用于富集培养（使用地球化学来帮助限制培养条件）。更广泛的影响。这个项目将扩大我们对微生物生物圈范围的了解。至少有一名研究生将参与涉及下一代测序，分子微生物生态技术和地球化学建模的跨学科研究。ALR将涉及一名注册的PSU太平洋岛民学生的研究和要求的研究巡航。来自布里奇沃特州立大学的本科生将参与流体采样项目，从而提供有意义和令人兴奋的研究经验。pi将通过撰写一般文章，在学校演讲，以及通过现有计划（例如通过PSU周六学院（http://www.saturdayacademy.org/））为学校教师提供继续教育，与公众分享新的深海喷口发现的兴奋。

Extreme environmental gradients exist at deep-sea hydrothermal vents where high temperature, low pH and reduced fluids mix with cold oxygenated seawater. This results in a plethora of microbes taking advantage of abundantly available microniches. From small subunit (16S) rRNA gene surveys and directed enrichment culturing of vent deposits from many sites, patterns in diversity are emerging that suggest that geochemical processes, particularly those that affect fluid pH, play a fundamental role in regulating microbial diversity and community composition. This a three year study at vent fields along the Eastern Lau Spreading Center (ELSC) to investigate the relationship between vent geochemistry and microbial community dynamics. The ELSC was chosen because it provides large and systematic changes in fluid and rock geochemistry, spreading rate, magmatic/tectonic processes, and proximity to the volcanic arc over its relatively short length of 397 km. The individual vent fields therefore provide excellent natural laboratories for exploring, in depth, the factors that influence the diversity and relationships of microbial communities associated with actively forming deep-sea hydrothermal deposits. The study will be carried out at 3 geochemically different hydrothermal fields along the ELSC. The scientists will document microbial community composition and diversity associated with hydrothermal deposits from each area for comparison with data obtained in 2009 and 2005. The close proximity of these geochemically distinct vent areas within the ELSC provides an ideal opportunity to investigate the effect of vent fluid and deposit geochemistry on the structure and function of microbial communities, as well as the specific roles of individual populations, associated with active hydrothermal deposits. The investigators hypothesize that, given the extreme environmental characteristics (e.g., low fluid pH and high iron at Mariner), they will see distinct differences in the metagenomes and particularly in the metatranscriptomes among the Kilo Moana, ABE and Mariner vent fields. The specific objectives are to: 1) Link geochemical and microbial dynamics along the ELSC (from 2005-­2013); 2) Use of metagenomic and transcriptomic data to explore biogeochemical cycles that are regulating the functional roles of the microbial communities in vent fields along the ELSC; and 3) Use the metagenomic information to enrich for targeted novel Thermoprotei and acidophiles. Active hydrothermal metal sulfide deposits and fluid samples will be collected from the vent fields along the ELSC. Bar-coded pyrosequencing of archaeal and bacterial 16S rRNA amplicons will be obtained for over eighty samples. The geochemical environment of the chimneys will be modeled to determine in situ geochemical conditions. These values will be used in statistical analyses to explore the factors affecting the observed differences in the communities. Using the 16S rRNA gene 454 pyrotags coupled with the geochemical characterization, specific samples will be selected for metagenomic and metatranscriptomic analyses (1-3 of each per site). The molecular information will be used to target specific samples that: (i) harbor novel unclassified diversity; (ii) have vent endemic lineages; and (iii) have acidophilic relatives from terrestrial systems, for enrichment culturing (using the geochemistry to help constrain culturing conditions). Broader Impacts. The project will expand our understanding of the extent of the microbial biosphere. At least one graduate student will participate in interdisciplinary studies that involve next-­generation sequencing, molecular microbial ecological techniques, and geochemical modeling. ALR will involve a registered PSU Pacific Islander student in the research and requested research cruise. Undergraduate students from Bridgewater State University will be involved in the fluid sampling program, thereby providing a meaningful and exciting research experiences. The PIs will share the excitement of new deep-sea vent discoveries with the public through writing general articles, giving lectures at schools, and through continuing education for school teachers through existing programs (e.g. through the Saturday Academy, PSU (http://www.saturdayacademy.org/).