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

智力上的功绩。铁氧化细菌群落(FeOB)在热液喷口地点很常见，已知在富含铁和低氧的微生物垫、热液沉积物、大洋地壳玄武岩和井筒流体中形成复杂的群落。来自太平洋周围地点的研究发现，齐塔蛋白细菌是这些FeOB群落中无处不在的成员。此前，来自南马里亚纳背弧的钻孔流体已被证明支持几种新的和独特的地方性Zeta变形杆菌谱系。从伊赫亚北部热液油田深层地下取样(IODP探险331)探索了这种深层地下FeOB生物多样性，并利用微好氧和厌氧培养条件进行了多次浓缩。从这些地下岩心样本中检测到了高达总细菌群落13%的泽塔变形杆菌。该项目扩展了巡航后的分析，重点是使用单细胞基因组学、社区水平的元基因组学和FeOB定向培养方法来评估这些FeOB地下群落。这种方法将使人们能够深入了解这些齐塔蛋白细菌的独特生理和新陈代谢，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。(从进化的角度)进行比较分析，以确定地下ZetaProteb细菌和生活在海底表面的ZetaProteb细菌之间的独特差异，是这一努力的组成部分。对于地球科学和海洋学领域感兴趣的科学家来说，更好地了解Zeta变形杆菌是主要感兴趣的，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，在几百万年(甚至可能数十亿年)以前的岩石记录中，仍然可以识别出与Zeta变形杆菌类似的形态结构，这使得它们具有古生物学(以及潜在的外部生物学)兴趣。随着对现存种群的了解不断增长，它们也有可能帮助我们了解过去地球历史上的环境变化。从实际的角度来看，这些有机体可以被认为是“微型机器”，可以旋转出以未知方式结合在一起的氢氧化铁。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，这项研究使我们有机会比较和对比已知的单系变形杆菌类别，研究泽塔蛋白细菌表层和表层谱系之间的差异，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外展机会成为可能，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.