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

较低的海洋地壳大部分尚未被探索，是地球上生物探索的最后前沿之一。初步数据表明，从印度洋西南亚特兰提斯海岸收集的海底地壳下部样本中，有一个活跃的地下生物圈，深度达海底以下790米。即使生命只存在于温度允许、流体流动可以输送碳和能源的可居住体积的一小部分，活跃的海洋地壳低层生物圈也会对深层碳收支产生影响，并对早期地球上可能存在的微生物群产生深入的了解。这引起了其他研究学科、教育工作者和学生的极大兴趣。K-12教育项目将利用外展合作者A.马丁内斯奠定的基础。马丁内斯是德克萨斯州伊格尔帕斯的一名七年级教师，曾作为钻探探险360的外展专家航行。马丁内斯在一所第一名学校工作，该学校有98%的西班牙裔学生和2%的美洲原住民学生，还有大量的英语学习者和移民。在每年的学校访问期间，项目调查员会亲自向学生介绍微生物学，并就海洋微生物学、项目以及如何从事与科学相关的职业进行讲座。此外，每月Skype会议与学生和pi更新他们的项目进展。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，并在R/V Katy上乘坐3小时的游轮，在此期间他们可以学习并帮助不同的海洋采样方法。该项目部分资助了两名研究生，一名伍兹霍尔大学本科生暑期学生，多名德克萨斯州a +M本科生的参与，以及两所机构的3名主要研究人员，其中包括一名早期职业研究员，他之前没有获得过自己的NSF支持。考虑到我们对海洋地壳下层的知识匮乏，这个项目将改变我们对这一广阔环境中生命的认识。该项目评估了这一地壳生物圈中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。海洋地壳下部代表了一个潜在的巨大生物圈，其微生物成分及其介导的生物地球化学循环可能通过断裂和地下流体流动与深海过程有关。亚特兰提斯滩代表了一个构造窗口，它直接在海底暴露出较低的海洋地壳。这使得海底钻探和环境研究能够改变我们对深海海底生物圈与海洋其他部分之间联系的理解。对360号探险队回收的岩石的初步分析表明，海水与下部海洋地壳的相互作用创造了多种地球化学条件，能够通过提供营养和化学能来支持各种微生物的生命。该项目是第一个对地下室样品中所有3个生命领域的微生物学进行跨学科研究，结合了多样性和“元组学”分析、营养添加实验分析、高通量培养和分离物的生理分析，包括评估它们利用特定碳源的能力、拉曼光谱和脂质生物标志物分析。比较基因组学用于将这些样本中与碳循环相关的基因和途径与其他深海环境发表的研究数据进行比较。收集到的样品提供了一个难得的、时间敏感的机会，可以详细了解微生物的生命、这种生命的可用碳和能量来源、微生物群的分布以及下海洋地壳与上覆的无光水柱之间生物地球化学过程的联系。

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.