Molecular Environmental Chemistry of Mn Oxide Biomineralization

这个环境分子科学合作研究活动（CRAEMS）奖给加利福尼亚大学圣地亚哥斯克里普斯海洋研究所是由化学部特别项目办公室支持。 除了支持研究所的布拉德利特博外，该奖项还通过子奖项支持普林斯顿大学的托马斯斯皮罗，斯坦福大学同步辐射实验室的约翰巴加和加州大学伯克利分校的加里森斯波西托。该奖项将解决细菌如何氧化锰，所产生的锰氧化物如何影响陆地和海洋环境中其他金属的化学性质，以及它们如何影响天然和外源性有机分子的化学和生物化学降解等问题。该项目将包括：（1）克隆和表达与细菌的Mn（II）氧化系统有关的基因产物，并利用生物化学和光谱方法对这些蛋白质进行表征，以阐明氧化锰形成的机制;（2）调查与其他金属离子和有机分子的交叉反应性，以评估Mn（II）氧化系统对环境的影响;（3）探索金属离子共污染物如何在氧化锰生物合成过程中被全细胞隔离;（4）表征生物氧化锰表面关于金属离子吸附和溶解的反应性，以及微生物代谢的有机基质的改变。将使用各种微生物、化学和光谱技术，如X射线吸收光谱、共振拉曼和FTIR。 微生物产生的锰氧化物在环境中普遍存在，并且具有高的转化有机和无机污染物（包括芳烃和硫化氢）的能力。了解锰氧化物的环境轨迹沿着的步骤，从生物化学机制，交叉反应与金属和有机物，对金属的固定和生物降解途径的氧化物的影响，将有助于阐明地球化学循环和设计修复策略的金属和有机污染。

This Collaborative Research Activities in Environmental Molecular Science (CRAEMS) Award to the University of California-San Diego Scripps Institute of Oceanography is supported by the Special Projects Office in the Chemistry Division. In addition to the support to Bradley Tebo at the Institute, the award also supports Thomas Spiro at Princeton University, John Bargar at the Stanford Synchrotron Radiation Laboratory and Garrison Sposito at UC-Berkeley, through subawards. The award will address the issues of how bacteria oxidize manganese, how the resulting manganese oxides influence the chemistry of other metals in both terrestrial and marine environments and how they affect chemical and biochemical degradation of natural and xenobiotic organic molecules. The project will encompass (1) cloning and expressing the gene products associated with the Mn (II)-oxidation system of bacteria and characterizing these proteins using biochemical and spectroscopic methods in order to elucidate the mechanisms of manganese oxide formation; (2) investigating cross-reactivity with other metal ions and with organic molecules, in order to evaluate the environmental influence of Mn (II) oxidation systems; (3) exploring how metal ion co-contaminants are sequestered during manganese oxide biogenesis by whole cells; and (4) characterizing the reactivity of biogenic manganese oxide surfaces with respect to metal ion sorption and dissolution, and the alteration of organic substrates for microbial metabolism. A variety of microbiological, chemical, and spectroscopic techniques such as x-ray absorption spectroscopy, resonance Raman and FTIR will be utilized. Microbially produced manganese oxides are ubiquitous in the environment and have high capacities to transform organic and inorganic pollutants including aromatic hydrocarbons and hydrogen sulfide. Understanding the steps along the environmental trajectory of manganese oxides, from biochemical mechanisms, to cross-reactivity with metals and organics, to the influence of the oxides on metals immobilization and on biodegradation pathways, will be useful in elucidating biogeochemical cycles and designing remediation strategies for metal and organic pollution.