Collaborative Research: Loihi Seamount as an Observatory for the Study of Neutrophilic Iron-Oxidizing Bacteria and the Microbial Iron Cycle

金属对生命的重要性早就被认识到了。铁是地壳中第四丰富的元素，也是第二丰富的氧化还原活性元素，使其成为最重要的环境金属。认识到这一点，最近对环境中微生物铁氧化还原转化的研究激增，导致了许多令人兴奋的发现，并提高了对这些过程的重要性的认识(Lovley 2000)。然而，这些研究大多集中在还原铁循环和生物体，如地细菌科。这在一定程度上是因为铁氧化生物体，特别是那些生活在pH中性附近的生物体，在实验室培养和研究一直是出了名的困难。然而，最近在这方面的成功导致了一些新的化学自养型铁氧化细菌(FeOB)的分离。对这些细菌的研究表明，无论是在生理上还是在系统发育上，都存在着显著的多样性。考虑到铁是地壳中最丰富的岩石自养能源，这或许并不令人惊讶，但与目前对他们的研究的关注不一致。该项目正在启动一个微生物观测站，用于研究铁氧化细菌(.FeMO.)在夏威夷海山，洛伊希。该项目的主要目的是阐明这类原核生物的全部生理、系统发育和生化多样性。Loihi之所以被选为研究地点，是因为：(1)以前曾在那里发现和研究过FeOB；(2)Loihi显示了广泛的FeOB生境：从热液到岩石，从低流量、低T(10C)渗漏到高流量、高T(60C)喷口；(3)以前的研究为这些研究提供了极好的地球化学框架；以及(4)Loihi非常方便，位于夏威夷大岛西南仅25英里处。该研究小组代表了有关FeOB的各种专业知识。FEMO项目的主要组成部分包括(1)FeOB的培养分析，(2)Fe氧化速率的动力学研究，(3)Fe氧化酶的生物化学研究，以及(4)FeOB定殖和固体岩石利用的生物地球化学研究。众所周知，微生物铁的氧化还原转化影响环境和人类健康，例如在有机污染物降解和通过吸附有毒放射性核苷酸，特别是在陆地和沿海海洋生物栖息地。在研究较少的深海少营养化自养FeOB中，最近被认为在生产新的生物质碳方面具有潜在的重要作用。这项研究正在导致在研究FeOB和了解它们的环境活动和能力方面取得重大进展，并将能够在许多难以到达的栖息地对它们进行更准确的预测。FEMO PIs主要参与世界卫生组织的初中和高中教师教育和提高工作。这些措施包括参加现有的暑期讲习班，开发新的学年周末迷你讲习班，以及让一名教师直接参与FEMO的实地工作。FEMO参与者还积极参与多个领域的高等教育，包括通过Praxis计划专门从新英格兰女子学院(Smith)招募女性和少数族裔本科生进行暑期实习。

AbstractThe importance of metals to life has long been appreciated. Iron (Fe) is the fourth most abundant element, and the second most abundant redox-active element in Earth's crust, rendering it the most important environmental metal. In recognition of this, a recent surge in research on microbial Fe redox transformations in the environment has resulted in many exciting discoveries and enhanced appreciation for the importance of these processes (Lovley 2000). Most of these studies, however, have focused on the reductive Fe cycle and organisms such as the Geobacteraceae. This is in part because Fe-oxidizing organisms, particularly those who inhabit circumneutral pH habitats, have been notoriously difficult to culture and study in the lab. However, recent successes on this front have resulted in the isolation of a number of novel chemolithoautotrophic Fe-oxidizing bacteria (FeOB). Studies of these bacteria have revealed a remarkable diversity, both physiologically and phylogenetically. This perhaps should not be surprising given that Fe is the most abundant lithoautotrophic energy source in Earth's crust, but is not in keeping with the present attention given to their study. This project is initiating a microbial observatory for the study of iron-oxidizing bacteria (.FeMO.) at the Hawaiian Seamount, Loihi. The major purpose of the project is to elucidate the full physiological, phylogenetic, and biochemical diversity of this group of prokaryotes. Loihi was selected as the study site because: (1) FeOB have been recognized and studied there previously; (2) Loihi displays a wide-range of FeOB habitats: from hydrothermal fluids to rocks, from low-flow, low-T (10C) seeps to high-flow, high-T (60C) vents; (3) previous studies provided an excellent geochemical framework on which to base these studies; and (4) Loihi is very accessible, located only 25 miles SW of the big island of Hawaii. The research group represents a cross-section of expertise on FeOB. Principal components of the FeMO project include (1) cultural analysis of FeOB, (2) kinetic studies on Fe-oxidation rates, (3) biochemical studies on the Fe oxidase, and (4) biogeochemical studies on colonization and solid rock utilization by FeOB. Microbial Fe redox transformations are well known to impact environmental and human health, for example in organic contaminant degradation and via sorption of toxic radionucleotides, particularly in terrestrial and coastal marine habitats. In the more poorly studied, oligotrophic deep-sea, chemoautotrophic FeOB have recently been recognized for their potentially important role in production of new biomass carbon. This research is leading to significant advances in the study of FeOB and understanding their environmental activities and capabilities, and would enable more accurate predictions about them in many poorly-accessible habitats. The FeMO PIs are involved heavily in middle and high-school teacher education and enhancement efforts at WHOI. These include participation in existing summer workshops, the development of a new school-year weekend mini-workshop, and the direct involvement of a teacher in the FeMO fieldwork. FeMO participants are also be strongly involved with higher education on multiple fronts, including the specific recruitment of female and minority undergraduates from a New England women's college (Smith) for summer internships via the Praxis program.