RUI: Iron-oxidizing Bacteria from the Okinawa Trough Deep Subsurface Biosphere

ABSTRACTIntellectual优点。铁氧化细菌（FeOB）群落在热液喷口处很常见，并且已知在微生物垫、热液沉积物、海洋地壳玄武岩和钻孔流体（以及其他）中形成复杂的群落，这些流体富含铁而低氧。来自太平洋周围地区的研究发现，Zetaproteobacteria是这些FeOB群落中无处不在的成员。此前，来自南马里亚纳Backarc的井眼流体已被证明支持几种新的独特的地方性Zetaproteobacteria谱系。从Iheya北部热液区深层地下采样（IODP Expedition 331）探索了深层地下FeOB生物多样性，并在嗜微氧和厌氧培养条件下获得了多重富集。从这些地下岩心样品中检测到的Zetaproteobacteria含量高达总细菌群落的13%。该项目扩展了巡航后的分析，重点使用单细胞基因组学、社区水平宏基因组学和FeOB定向培养方法来评估这些FeOB地下群落。这种方法将有助于深入了解这些Zetaproteobacteria的独特生理和代谢，从而展示它们如何在这些复杂的地下微生物群落中生存、竞争和生长的关键特征。比较分析（从进化的角度）来确定地下Zetaproteobacteria和生活在海底表面上的Zetaproteobacteria之间的独特差异是这项工作的一个组成部分。更广泛的影响。更好地了解Zetaproteobacteria是对地球科学和海洋学领域感兴趣的科学家的中心兴趣，因为它们说明了微生物如何影响地球化学循环和矿物沉积。此外，与Zetaproteobacteria产生的形态结构相似的形态结构仍然可以在一亿年前（甚至可能数十亿年前）的岩石记录中被识别出来，这使得它们具有古生物学（以及潜在的外太空生物学）的兴趣。随着对现存种群知识的增长，它们也有可能帮助我们了解过去地球历史上的环境变化。从实用的角度来看，这些生物可以被认为是“微型机器”，它们以未知的方式纺出氧化铁的线。众所周知，这些氧化物与一系列其他金属、有机化合物和营养物质高度反应，从而影响许多其他生物地球化学循环。特别是，本研究提供了比较和对比已知单系变形菌类的机会，以研究Zetaproteobacteria的地下和表面谱系之间的差异，从而为微生物生物地理学提供基本线索。这项工作将使丰富的教育推广机会成为可能，包括研究生教育、本科生研究经验和教师培训。

ABSTRACTIntellectual Merit. Communities of Fe-oxidizing Bacteria (FeOB) are common at sites of hydrothermal venting and are known to form complex communities in microbial mats, hydrothermal sediments, oceanic crustal basalts and borehole fluids (among others) that are iron-rich and low in oxygen. Studies from sites around the Pacific Ocean have found the Zetaproteobacteria to be ubiquitous members of these FeOB communities. Previously, borehole fluids from the Southern Mariana Backarc have been shown to support several novel and distinct lineages of endemic Zetaproteobacteria. Sampling from the deep subsurface at the Iheya North hydrothermal field (IODP Expedition 331) explores this deep subsurface FeOB biodiversity and has resulted in multiple enrichments using both microaerophilic and anaerobic culturing conditions. Zetaproteobacteria have been detected at levels up to 13% of the total bacterial community from these subsurface core samples. This project expands post-cruise analyses to focus on assessing these FeOB subsurface communities using a combined single cell genomics, community-level metagenomics and a FeOB directed cultivation approach. This approach will allow insights into the exclusive physiology and metabolism of these Zetaproteobacteria thereby demonstrating key features as to how they survive, compete and grow within these complex subsurface microbial communities. A comparative analysis (from an evolutionary standpoint) to determine the unique differences between subsurface Zetaproteobacteria and those living above the seafloor surface is an integral part of this effort.Broader Impacts. A better understanding of Zetaproteobacteria is of central interest to scientists interested in areas of earth science and oceanography because they illustrate how microbes can influence geochemical cycling and mineral deposition. Furthermore, morphological structures similar to those produced by Zetaproteobacteria can still be identified 100's of millions (and possibly billions) of years back in the rock record, making them of paleontological (and potentially of exobiological) interest. As knowledge of extant populations grows, it is possible they will also help to inform us of environmental change in past Earth history. From a practical standpoint, these organisms might be thought of as 'micro-machines', spinning out threads of iron oxyhydroxide that coalesce in unknown ways. These oxides are known to be highly reactive with a range of other metals, organic compounds, and nutrients, thus impacting many other biogeochemical cycles. In particular, this study allows the opportunity to compare and contrast a known monophyletic class of Proteobacteria, to study the differences between subsurface and supersurface lineages of Zetaproteobacteria, thereby yielding fundamental clues into microbial biogeography. A wealth of educational outreach opportunities will be made possible by this work, including graduate education, research experiences for undergraduates, and teacher training.