Collaborative Research: Characterization of Microbial Transformations in Basement Fluids, from Genes to Geochemical Cycling

目前的估计表明，能够维持生命的洋壳的体积与海洋的体积相当。迄今为止，人们对海底以下微生物群落的组成或功能能力，或它们对海洋化学的影响以及随后对全球海洋地球化学循环的后果知之甚少。该项目的重点是了解微生物群落和年轻地壳流体中的流体化学之间的关系，这些流体负责地壳中能量，营养物质和生物体的运输。具体而言，PI将耦合微生物活性测量，包括自养碳，氮和硫代谢以及矿物氧化物还原，定量评估功能基因表达和基底流体中的地球化学转化。通过一套全面的现场和船上分析，这项研究将在我们对海底下生物圈的微生物生态学和地球化学的理解方面取得跨学科的进展。这项工作的重点是北池，这是一个孤立的沉积物池，位于大西洋中脊西侧700万至800万年前的海脊侧翼洋壳上。北池目前是IODP第336次考察的钻探目标，在此期间，它将配备三个海底地下观测站。该项目将利用这一机会，在两次德美研究巡航中在北池塘进行有针对性的独特采样，以实现三个主要目标：1。以确定北池不同的基底流体层是否存在不同的微生物群落和化学环境，以及它们在钻井后两年期间的变化程度。通过微生物介导的碳、氮和硫物质在北池基底流体中的转化来量化自养代谢的程度。以确定北池基底流体中悬浮颗粒矿物氧化物的程度，并表征其作为流体宿主微生物群落氧化剂的作用。具体成果包括微生物活性和基因表达以及地球化学转化的定量评估。该计划建立在北池综合研究目标的基础上，将为指导该计划和未来深层生物圈研究计划的发展提供重要数据。结果将增加了解微生物的生命和化学在年轻的海洋地壳，以及提供新的见解控制的分布和活动的海洋微生物群落在整个世界oceans.Broader ImpactsThere是无处不在的冷，海洋地壳的微生物群落没有数据，拟议的工作的重点。这是微生物生态学、化学和深海海洋学的一个跨学科项目，与国际和国家研究和教育组织有直接联系。它利用了美国和德国的PI和合作者之间的长期合作，包括最近成立的NSF科学和技术中心，名为“暗能量生物圈调查中心”（C-DEBI）和NSF研究协调网络，专注于深层生物圈。这项关于微生物介导的基底流体地球化学转化的工作是可以实现的，也是及时的，这项工作的方法开发和结果将补充目前和未来对胡安·德富卡海岭的微生物和地球化学调查，作为IODP和OOI区域尺度节点的一部分。公众宣传工作将利用Zephyr教育基金会独特的海洋科学计划，纳入一个专注于海洋微生物学的简短教育模块，该模块将针对7年级到大学的学生量身定制。该模块将强调海洋微生物对环境可持续性，人类健康以及地球上生命的起源和进化的重要性。该项目还支持一名研究生，一名本科生和两名博士后研究人员的研究和职业发展。学生和博士后将通过新兴和现有的NSF计划与对深层生物圈微生物学和化学感兴趣的更大的研究人员社区进行接触。

Intellectual MeritCurrent estimates suggest that the volume of ocean crust capable of sustaining life is comparable in magnitude to that of the oceans. To date, there is little understanding of the composition or functional capacity of microbial communities in the sub-seafloor, or their influence on the chemistry of the oceans and subsequent consequences for global biogeochemical cycles. This project focuses on understanding the relationship between microbial communities and fluid chemistry in young crustal fluids that are responsible for the transport of energy, nutrients, and organisms in the crust. Specifically, the PIs will couple microbial activity measurements, including autotrophic carbon, nitrogen and sulfur metabolisms as well as mineral oxide reduction, with quantitative assessments of functional gene expression and geochemical transformations in basement fluids. Through a comprehensive suite of in situ and shipboard analyses, this research will yield cross-disciplinary advances in our understanding of the microbial ecology and geochemistry of the sub-seafloor biosphere. The focus of the effort is at North Pond, an isolated sediment pond located on ridge flank oceanic crust 7-8 million years old on the western side of the Mid-Atlantic Ridge. North Pond is currently the target for drilling on IODP expedition 336, during which it will be instrumented with three sub-seafloor basement observatories. The project will leverage this opportunity for targeted and distinct sampling at North Pond on two German-US research cruises to accomplish three main objectives:1. to determine if different basement fluid horizons across North Pond host distinct microbial communities and chemical milieus and the degree to which they change over a two-year post-drilling period.2. to quantify the extent of autotrophic metabolism via microbially-mediated transformations in carbon, nitrogen, and sulfur species in basement fluids at North Pond.3. to determine the extent of suspended particulate mineral oxides in basement fluids at North Pond and to characterize their role as oxidants for fluid-hosted microbial communities.Specific outcomes include quantitative assessments of microbial activity and gene expression as well as geochemical transformations. The program builds on the integrative research goals for North Pond and will provide important data for guiding the development of that and future deep biosphere research programs. Results will increase understanding of microbial life and chemistry in young oceanic crust as well as provide new insights into controls on the distribution and activity of marine microbial communities throughout the worlds oceans.Broader ImpactsThere are no data about microbial communities in ubiquitous cold, oceanic crust, the emphasis of the proposed work. This is an interdisciplinary project at the interface of microbial ecology, chemistry, and deep-sea oceanography with direct links to international and national research and educational organizations. It leverages on a long-term collaboration between the PIs and collaborators in both the US and Germany, including the recently formed NSF Science and Technology Center entitled "Center for Dark Energy Biosphere Investigations" (C-DEBI) and the NSF Research Coordination Network focused on the deep biosphere. This work on microbially mediated geochemical transformations in basement fluids is both attainable and timely, and methods development and results from this work will complement current and future microbial and geochemical investigations on the Juan de Fuca Ridge as part of both IODP and the OOI Regional Scale Node. The public outreach effort will utilize The Zephyr Education Foundation's unique marine science program to incorporate a short educational module focused on marine microbiology that will be tailored to the grade levels 7 through college. The module will emphasize the importance of marine microbes to environmental sustainability, human health, and the origin and evolution of life on our planet. The project also supports the research and career development of one graduate student, one undergraduate student, and two postdoctoral researchers. Students and postdocs will to engage with the larger community of researchers interested in deep biosphere microbiology and chemistry through emerging and existing NSF programs.