Enzymatic microbial Mn(II) oxidation and Mn biooxide production in the Guaymas Basin deep-sea hydrothermal plume
Enzymatic microbial Mn(II) oxidation and Mn biooxide production in the Guaymas Basin deep-sea hydrothermal plume
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DOI：
10.1016/j.gca.2009.07.039
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发表时间：
2009-11-01
影响因子：
5
通讯作者：
Tebo, Bradley M.
中科院分区：
文献类型：
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作者：
Dick, Gregory J.;Clement, Brian G.;Tebo, Bradley M.
微生物在深海热液羽流中介导生物地球化学反应方面发挥重要作用，但对这些转化的机制知之甚少。在加州湾的瓜伊马斯盆地，热液喷口将含有溶解的Mn（II）（dMn）的流体注入盆地的深水沃茨，在那里被氧化并沉淀为Mn（III/IV）氧化物微粒，形成浑浊的热液“云”。以前的研究预测，在GB的dMn的停留时间极短，并建议他们是微生物介导的Mn（II）氧化和沉淀的结果。在这里，我们提出了微生物地球化学的结果，支持在GB热液羽驱动Mn（II）氧化的微生物的核心作用，酶是主要的催化剂。对于深海热液羽流，GB下的dMn去除速率非常快（高达2 nM/h）。这些快速的速率仅在羽流内观察到，而不是在GB羽流上方的背景深海水中或邻近卡门盆地的GB羽流深度（类似于1750-2000米），那里没有已知的排气。dMn去除在缺氧条件下和生物毒物叠氮化钠的存在下被显著抑制。一个显着的温度最佳dMn去除率（类似于40摄氏度）和饱和样（即米氏）响应O-2浓度进行了观察，表明酶的机制。dMn去除耐用于选择孢子形成生物体的热处理，但对低浓度的添加的Cu非常敏感，这是推定的Mn（II）氧化酶所需的辅因子。扩展X射线吸收。电子结构光谱（EXAFS）和同步辐射X射线衍射（SR-XRD）显示锰氧化物具有六方水钠锰矿或δ-MnO 2样矿物结构，表明这些新形成的深海锰氧化物与实验室细菌培养产生的原生生物锰氧化物惊人地相似。总的来说，这些结果揭示了一个有力的锰地球化学循环GB热液羽，其中一个独特的微生物群落酶催化快速Mn（II）氧化和锰生物氧化物的生产。(C)2009爱思唯尔有限公司保留所有权利。
Microorganisms play important roles in mediating biogeochemical reactions in deep-sea hydrothermal plumes, but little is known regarding the mechanisms that underpin these transformations. At Guaymas Basin (GB) in the Gulf of California, hydrothermal vents inject fluids laden with dissolved Mn(II) (dMn) into the deep waters of the basin where it is oxidized and precipitated as particulate Mn(III/IV) oxides, forming turbid hydrothermal "clouds". Previous studies have predicted extremely short residence times for dMn at GB and suggested they are the result of microbially-mediated Mn(II) oxidation and precipitation. Here we present biogeochemical results that support a central role for microorganisms in driving Mn(II) oxidation in the GB hydrothermal plume, with enzymes being the primary catalytic agent. dMn removal rates at GB are remarkably fast for a deep-sea hydrothermal plume (up to 2 nM/h). These rapid rates were only observed within the plume, not in background deep-sea water above the GB plume or at GB plume depths (similar to 1750-2000 m) in the neighboring Carmen Basin, where there is no known venting. dMn removal is dramatically inhibited under anoxic conditions and by the presence of the biological poison, sodium azide. A conspicuous temperature optimum of dMn removal rates (similar to 40 degrees C) and a saturation-like (i.e. Michaelis-Menten) response to O-2 concentration were observed, indicating an enzymatic mechanism. dMn removal was resistant to heat treatment used to select for spore-forming organisms, but very sensitive to low concentrations of added Cu, a cofactor required by the putative Mn(II)-oxidizing enzyme. Extended X-ray absorption. ne structure spectroscopy (EXAFS) and synchrotron radiation-based X-ray diffraction (SR-XRD) revealed the Mn oxides to have a hexagonal birnessite or delta-MnO2-like mineral structure, indicating that these freshly formed deep-sea Mn oxides are strikingly similar to primary biogenic Mn oxides produced by laboratory cultures of bacteria. Overall, these results reveal a vigorous Mn biogeochemical cycle in the GB hydrothermal plume, where a distinct microbial community enzymatically catalyzes rapid Mn(II) oxidation and the production of Mn biooxides. (C) 2009 Elsevier Ltd. All rights reserved.