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

摘要金属对生命的重要性长期以来一直受到人们的重视。 铁 (Fe) 是地壳中第四丰富的元素，也是地壳中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，产生了许多令人兴奋的发现，并增强了人们对这些过程重要性的认识（Lovley 2000）。 然而，大多数这些研究都集中在还原铁循环和地杆菌科等生物体上。 部分原因是铁氧化生物体，特别是那些生活在中性pH值环境中的生物体，在实验室中培养和研究是出了名的困难。 然而，最近在这方面取得的成功已经导致分离出许多新型化能自养铁氧化细菌（FeOB）。 对这些细菌的研究揭示了生理学和系统发育学上显着的多样性。 鉴于铁是地壳中最丰富的岩石自养能源，这或许并不令人惊讶，但这与目前对他们研究的关注并不相符。 该项目正在洛伊希夏威夷海山启动一个微生物观测站，用于研究铁氧化细菌 (.FeMO.)。该项目的主要目的是阐明这组原核生物的完整生理、系统发育和生化多样性。 选择Loihi作为研究地点的原因是：（1）FeOB在此之前已被识别和研究； (2) Loihi 展示了广泛的 FeOB 栖息地：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) 先前的研究为这些研究提供了良好的地球化学框架； (4) 洛伊希 (Loihi) 交通便利，距夏威夷大岛西南仅 25 英里。该研究小组代表了 FeOB 领域的跨领域专业知识。 FeMO项目的主要组成部分包括（1）FeOB的文化分析，（2）Fe氧化速率的动力学研究，（3）Fe氧化酶的生化研究，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，微生物铁氧化还原转化会影响环境和人类健康，例如有机污染物降解和有毒放射性核苷酸的吸附，特别是在陆地和沿海海洋生境中。 在研究较少的寡营养深海中，化能自养 FeOB 最近因其在新生物质碳生产中的潜在重要作用而被认识到。 这项研究在 FeOB 的研究和了解其环境活动和能力方面取得了重大进展，并将在许多交通不便的栖息地对它们进行更准确的预测。 FeMO PI 积极参与 WHOI 的初中和高中教师教育和增强工作。 其中包括参加现有的夏季研讨会、开发新的学年周末小型研讨会以及教师直接参与 FeMO 实地考察。 FeMO 参与者还积极参与多方面的高等教育，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.