Collaborative Research: Geochemical effects on the functional microbial community dynamics of hydrothermal deposits along the Eastern Lau Spreading Center

在深海热液喷口存在极端的环境梯度，在那里，高温、低pH值和减少的流体与冷的含氧海水混合。这导致大量微生物利用大量可用的微核体。从小亚基(16S)rRNA基因调查和许多地点喷口沉积物的定向浓缩培养中，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的过程，在调节微生物多样性和群落组成方面发挥了基础作用。这是一项为期三年的研究，在东部刘氏扩散中心(ELSC)沿线的喷口领域，研究喷口地球化学与微生物群落动态的关系。之所以选择ELSC，是因为它在相对较短的397公里长度上提供了流体和岩石地球化学、扩张速度、岩浆/构造过程以及与火山弧的接近程度的大而系统的变化。因此，各个喷口区域为深入探索影响与活跃形成深海热液矿床有关的微生物群落多样性和关系的因素提供了极好的天然实验室。这项研究将在ELSC沿线三个不同的地球化学热液领域进行。科学家们将记录每个地区与热液沉积有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。ELSC内这些在地球化学上截然不同的喷口区域非常接近，这为研究喷口流体和矿床地球化学对微生物群落结构和功能的影响，以及与活跃的热液矿床有关的单个种群的具体作用提供了理想的机会。研究人员推测，考虑到极端的环境特征(例如，Mariner的低流体pH和高铁)，他们将看到基洛莫阿纳、阿贝和Mariner喷口气田的元基因组，特别是元翻译的明显差异。具体目标是：1)将ELSC沿线的地球化学和微生物动力学联系起来(从2005年至2013年)；2)使用元基因组和转录组数据来探索调节ELSC沿线喷口区域微生物群落功能作用的生物地球化学循环；以及3)利用元基因组信息来丰富目标新的热蛋白和嗜酸菌。将从ELSC沿线的喷口区域收集活动的热液金属硫化物矿床和流体样本。将对80多个样本进行古细菌和细菌16S rRNA扩增的条形码焦磷酸测序。将对烟囱的地球化学环境进行模拟，以确定现场的地球化学条件。这些值将用于统计分析，以探索影响社区中观察到的差异的因素。利用16S rRNA基因454焦糖结合地球化学特征，将选择特定的样品进行元基因组和元转录分析(每个位点1-3个)。分子信息将被用来针对以下特定样本：(I)具有新的未分类多样性；(Ii)具有喷口特有谱系；以及(Iii)具有来自陆地系统的嗜酸亲缘关系，用于丰富培养(利用地球化学帮助限制培养条件)。更广泛的影响。该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将让一名注册的PSU太平洋岛民学生参与研究，并要求进行研究巡航。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。PIS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/).