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值和还原流体与含氧的冷海水混合。这导致大量的微生物利用大量可用的微生态系统。从小亚基（16 S）rRNA基因调查和直接富集培养喷口存款从许多网站，多样性的模式正在出现，这表明，地球化学过程，特别是那些影响流体pH值，在调节微生物多样性和社区组成发挥了根本性的作用。这是一项为期三年的研究，在喷口领域沿着东劳扩散中心（ELSC）调查喷口地球化学和微生物群落动态之间的关系。选择ELSC是因为它在流体和岩石地球化学、扩张速率、岩浆/构造过程以及在其相对较短的397公里长度上接近火山弧方面提供了大而系统的变化。因此，各个喷口区提供了极好的天然实验室，可用于深入探索影响与深海热液矿床活跃形成有关的微生物群落的多样性和相互关系的因素。该研究将在沿ELSC沿着3个地球化学性质不同的热液区进行。科学家们将记录每个地区与热液矿床相关的微生物群落组成和多样性，以与2009年和2005年获得的数据进行比较。ELSC内这些地球化学性质不同的喷口区非常接近，这为研究喷口流体和存款地球化学对微生物群落结构和功能的影响以及与活跃热液矿床有关的各个种群的具体作用提供了一个理想的机会。研究人员假设，考虑到极端的环境特征（例如，低流体pH值和高铁在水手），他们将看到在宏基因组，特别是在基洛莫阿纳，ABE和水手喷口领域之间的元转录组的明显差异。具体目标是：1）将地球化学和微生物动力学沿着ELSC（2005年至2013年12月）联系起来; 2）利用宏基因组和转录组数据探索调节ELSC沿着喷口区微生物群落功能作用的地球化学循环; 3）利用宏基因组信息丰富目标新颖的热蛋白和嗜酸菌。将从沿着ELSC的喷口区收集活跃的热液金属硫化物矿床和流体样本。将获得80多个样本的古细菌和细菌16 S rRNA扩增子的条形码焦磷酸测序。将模拟烟囱的地球化学环境，以确定原位地球化学条件。这些数值将用于统计分析，以探讨影响观察到的社区差异的因素。使用16 S rRNA基因454 pyrotags结合地球化学表征，将选择特定样本进行宏基因组和元转录组分析（每个研究中心各1-3份）。分子信息将用于针对以下特定样本进行富集培养（利用地球化学帮助限制培养条件）：㈠具有新的未分类多样性; ㈡具有喷口特有谱系; ㈢具有来自陆地系统的嗜酸亲缘物种。更广泛的影响。该项目将扩大我们对微生物生物圈范围的理解。至少有一名研究生将参加跨学科的研究，涉及下一代测序，分子微生物生态技术和地球化学建模。ALR将让一名注册的PSU太平洋岛民学生参与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计划，从而提供一个有意义的和令人兴奋的研究经验。研究所将通过撰写一般性文章、在学校讲课以及通过现有方案（例如通过PSU星期六学院（http：//www.saturdayacademy.org/））对学校教师进行继续教育，与公众分享新发现深海喷口的兴奋之情。

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/).