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

知识价值铁氧化细菌（FeOB）群落在热液喷口处很常见，已知它们在微生物席、热液沉积物、大洋地壳玄武岩和富含铁和低氧的钻孔流体（等）中形成复杂的群落。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。以前，钻孔流体从南马里亚纳弧已被证明支持几个新的和独特的血统的地方性Zetaproteobacteria。从Iheya North热液田（IODP Expedition 331）的深层地下取样探索了这种深层地下FeOB生物多样性，并使用微需氧和厌氧培养条件进行了多次富集。Zetaproteobacteria已被检测到的水平高达13%的总细菌群落从这些地下岩心样品。该项目扩展了巡航后分析，重点是使用组合的单细胞基因组学，社区级宏基因组学和FeOB定向培养方法评估这些FeOB地下社区。这种方法将允许深入了解这些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。从进化的角度进行比较分析，以确定地下Zetaproteobacteria和那些生活在海底表面以上的独特差异是这项工作的一个组成部分。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核心兴趣，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岩石记录中识别出数百万（甚至可能是数十亿）年，使它们成为古生物学（以及潜在的外星生物学）的兴趣。随着对现存种群的了解的增加，它们也可能有助于我们了解过去地球历史中的环境变化。从实际的角度来看，这些生物体可以被认为是“微型机器”，纺出以未知方式结合的羟基氧化铁线。已知这些氧化物与一系列其他金属、有机化合物和营养物具有高度反应性，从而影响许多其他生物地球化学循环。特别是，这项研究允许的机会，比较和对比已知的单系类变形菌，研究Zetaproteobacteria的地下和超表面谱系之间的差异，从而产生的基本线索，进入微生物微生物学。这项工作将提供丰富的教育推广机会，包括研究生教育、本科生的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.