Bacterial Manganese (II) Oxidation in the Guaymas Basin Hydrothermal Plume

热液喷口是溶解锰(II)的全球重要来源，它是生物体必需的微量营养素，也是热液活动的宝贵示踪剂。在含氧水中，如热液羽流，可溶的Mn(II)最终被氧化成Mn(III/IV)氧化物。这些“海洋清道夫”(Goldberg 1954)是一种高活性矿物，已知可以隔离多种金属，并参与与多种无机和有机化合物的氧化还原反应，因此在海洋地球化学中发挥着重要作用。细菌在热液喷口和其他环境中催化将Mn(II)氧化成Mn(III/IV)，因此被认为是形成天然Mn(III/IV)氧化物矿物的原因。虽然许多研究表明细菌是环境中观察到的快速锰氧化速率的罪魁祸首，但对所涉及的生物、锰生物矿化的机制(S)和产物以及锰(II)氧化的生物功能知之甚少。在这项研究中，来自加州大学圣地亚哥分校斯克里普斯海洋研究所的研究人员将确定导致瓜伊马斯盆地(GB)喷口羽流中锰氧化的细菌群落，确定氧化锰生物矿化的分子机制和产物，并阐明最近在热液喷口附近分离的锰氧化细菌中发现的核酮糖-1，5-二磷酸羧基酶(Rubisco)基因的作用。利用对细菌氧化分子生物学的新见解和先进的光谱技术，将研究GB热液羽流中锰氧化的机理(S)和产物。将设计分子探针来分析环境多样性和参与锰氧化的基因的分布。将在GB羽流水域中测量一系列条件下的锰氧化速率，以检验我们关于锰氧化特定分子机制的假说。X射线吸收光谱和同步辐射X射线衍射法将用于表征天然锰氧化物和锰氧化菌产生的反应中间体和产物。为了研究细菌锰氧化的功能，科学家们将研究最近从深海热液喷口分离出来的锰氧化细菌中参与自养碳固定(Rubisco)的基因的作用。为了检测这些基因的表达，将对锰氧化细菌分离株进行实验室(生理学)实验和野外工作。

ABSTRACTOCE- 0352081Hydrothermal vents are a globally significant source of dissolved manganese (II), an essential micronutrient for organisms and a valuable tracer of hydrothermal activity. In oxic waters such as hydrothermal plumes, soluble Mn(II) is eventually oxidized to Mn(III/IV) oxides. These "scavengers of the sea" (Goldberg 1954) are highly reactive minerals that are known to sequester a variety of metals and participate in redox reactions with a wide range of inorganic and organic compounds, thus playing an important role in marine geochemistry. Bacteria catalyze the oxidation of Mn(II) to Mn(III/IV) at hydrothermal vents and other environments and are thus thought to be responsible for the formation of natural Mn(III/IV) oxide minerals. Although many studies have shown that bacteria are responsible for the rapid Mn oxidation rates observed in the environment, relatively little is known about the organisms involved, the mechanism(s) and products of Mn biomineralization, and the biological function of Mn(II) oxidation. In this study, researchers from the University of California- San Diego Scripps Institute of Oceanography will identify the bacterial community responsible for Mn oxidation in Guaymas Basin (GB) vent plumes, determine the molecular mechanism and products of Mn oxide biomineralization, and elucidate the role of ribulose-1,5-bisphosphate carboxylase (rubisco) genes recently found in Mn-oxidizing bacteria isolated near hydrothermal vents. The mechanism(s) and products of Mn oxidation in GB hydrothermal plumes will be investigated utilizing new insights into the molecular biology of bacterial oxidation and advanced spectroscopic techniques. Molecular probes will be designed to analyze the environmental diversity and distribution of genes involved in Mn oxidation. Mn oxidation rates will be measured in GB plume waters under a range of conditions designed to test our hypotheses concerning specific molecular mechanisms of Mn oxidation. X-ray absorption spectroscopy and synchrotron radiation X-ray diffraction will be used to characterize natural Mn oxides and reaction intermediates and products produced by Mn-oxidizing isolates. To investigate the function of bacterial Mn oxidation, the scientists will examine the role of genes involved in autotrophic carbon fixation (rubisco) in Mn oxidizing bacteria recently isolated from deep-sea hydrothermal vents. To detect expression of these genes both laboratory (physiology) experiments on Mn-oxidizing bacterial isolates and fieldwork will be performed.