Collaborative Research: Delineating The Microbial Diversity and Cross-domain Interactions in The Uncharted Subseafloor Lower Crust Using Meta-omics and Culturing Approaches

下层洋壳在很大程度上仍未被勘探，是地球上生物勘探的最后前沿之一。初步数据表明，在印度洋西南部亚特兰蒂斯浅滩采集的下层洋壳样本中，有一个活跃的地下生物圈，深达海底以下790米。即使在温度允许和流体流动可以提供碳和能源的情况下，生命只存在于可居住体积的一小部分，活跃的下层洋壳生物圈也将对深层碳收支产生影响，并对地球早期可能存在的微生物群有深入的了解。这是其他研究学科、教育工作者和学生都非常感兴趣的。K-12教育项目将利用推广合作者A·马丁内斯奠定的基础，他是德克萨斯州伊格尔帕斯的一名7年级教师，曾作为钻井远征360的推广专家航行。马丁内斯在一所TITL1学校工作，那里有98%的西班牙裔学生和2%的美国原住民学生，以及大量的英语学习者和移民。每年都会进行学校访问，在此期间，项目调查人员将介绍向学生介绍微生物学的实践活动，并就海洋微生物学、项目和如何从事与科学有关的职业进行演讲。此外，每月与学生和PI举行Skype会议，向他们通报项目进展情况。学生们每年都会前往德克萨斯大学海洋科学研究所，在那里他们可以参观校园，并乘坐R/V凯蒂号乘坐3个小时的邮轮，在此期间，他们可以了解和帮助不同的海洋采样方法。该项目部分支持两名研究生、一名伍兹霍尔大学本科生暑期学生、多名德克萨斯A+M本科生的参与，以及两所机构的3名首席调查人员，其中包括一名之前从未接受过NSF资助的早期职业研究人员。鉴于对下层洋壳知识的匮乏，这个项目准备改变我们对这一广阔环境中生命的理解。该项目评估了这一地壳生物圈所有三个生命领域的代谢功能，重点是营养循环和评估与其他深海微生物栖息地的联系。下部洋壳代表着一个潜在的巨大生物圈，其微生物成分及其调节的生物地球化学循环很可能通过断层作用和地下流体流动与深海过程相联系。亚特兰蒂斯浅滩代表着一个构造窗口，直接暴露在海底的下部洋壳。这使得海底钻探和对环境的研究能够改变我们对深海海底生物圈和海洋其他部分之间联系的理解。对从远征360中发现的岩石的初步分析表明，海水与下层洋壳的相互作用创造了不同的地球化学条件，能够通过提供营养和化学能量来支持不同的微生物生命。该项目是首次对基底样品中所有三个生命领域的微生物学进行跨学科研究，结合了多样性和“荟萃组学”分析、营养添加实验分析、高通量培养和分离株的生理分析，包括评估它们利用特定碳源的能力、拉曼光谱和脂肪生物标记物分析。比较基因组学被用来将这些样本中与碳循环相关的基因和途径与发表的其他深海环境研究的数据进行比较。所收集的样本提供了一个难得的、具有时间敏感性的机会，以详细了解微生物生命、生命中可利用的碳和能源、微生物区系的扩散以及下部洋壳和上层无光水柱之间的生物地球化学过程中的联系。

The lower ocean crust has remained largely unexplored and represents one of the last frontiers for biological exploration on Earth. Preliminary data indicate an active subsurface biosphere in samples of the lower oceanic crust collected from Atlantis Bank in the SW Indian Ocean as deep as 790 m below the seafloor. Even if life exists in only a fraction of the habitable volume where temperatures permit and fluid flow can deliver carbon and energy sources, an active lower oceanic crust biosphere would have implications for deep carbon budgets and yield insights into microbiota that may have existed on early Earth. This is all of great interest to other research disciplines, educators, and students alike. A K-12 education program will capitalize on groundwork laid by outreach collaborator, A. Martinez, a 7th grade teacher in Eagle Pass, TX, who sailed as outreach expert on Drilling Expedition 360. Martinez works at a Title 1 school with ~98% Hispanic and ~2% Native American students and a high number of English Language Learners and migrants. Annual school visits occur during which the project investigators present hands on-activities introducing students to microbiology, and talks on marine microbiology, the project, and how to pursue science related careers. In addition, monthly Skype meetings with students and PIs update them on project progress. Students travel to the University of Texas Marine Science Institute annually, where they get a campus tour and a 3-hour cruise on the R/V Katy, during which they learn about and help with different oceanographic sampling approaches. The project partially supports two graduate students, a Woods Hole undergraduate summer student, the participation of multiple Texas A+M undergraduate students, and 3 principal investigators at two institutions, including one early career researcher who has not previously received NSF support of his own. Given the dearth of knowledge of the lower oceanic crust, this project is poised to transform our understanding of life in this vast environment. The project assesses metabolic functions within all three domains of life in this crustal biosphere, with a focus on nutrient cycling and evaluation of connections to other deep marine microbial habitats. The lower ocean crust represents a potentially vast biosphere whose microbial constituents and the biogeochemical cycles they mediate are likely linked to deep ocean processes through faulting and subsurface fluid flow. Atlantis Bank represents a tectonic window that exposes lower oceanic crust directly at the seafloor. This enables seafloor drilling and research on an environment that can transform our understanding of connections between the deep subseafloor biosphere and the rest of the ocean. Preliminary analysis of recovered rocks from Expedition 360 suggests the interaction of seawater with the lower oceanic crust creates varied geochemical conditions capable of supporting diverse microbial life by providing nutrients and chemical energy. This project is the first interdisciplinary investigation of the microbiology of all 3 domains of life in basement samples that combines diversity and "meta-omics" analyses, analysis of nutrient addition experiments, high-throughput culturing and physiological analyses of isolates, including evaluation of their ability to utilize specific carbon sources, Raman spectroscopy, and lipid biomarker analyses. Comparative genomics are used to compare genes and pathways relevant to carbon cycling in these samples to data from published studies of other deep-sea environments. The collected samples present a rare and time-sensitive opportunity to gain detailed insights into microbial life, available carbon and energy sources for this life, and of dispersal of microbiota and connections in biogeochemical processes between the lower oceanic crust and the overlying aphotic water column.