Magnetite as a precursor for green rust through the hydrogenotrophic activity of the iron-reducing bacteria Shewanella putrefaciens
Magnetite as a precursor for green rust through the hydrogenotrophic activity of the iron-reducing bacteria Shewanella putrefaciens
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DOI：
10.1111/gbi.12170
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发表时间：
2016-05-01
期刊：
影响因子：
3.7
通讯作者：
Ruby, C.
中科院分区：
文献类型：
--
作者：
Etique, M.;Jorand, F. P. A.;Ruby, C.
磁铁矿((Fe2O4)-Fe-II-O-III)通常被认为是Fe-III矿物(如铁水铁矿、轻铁矿、赤铁矿)生物还原或Fe-II化合物(如菱铁矿)生物氧化的稳定最终产物，绿锈(GR)是混合的Fe-II-Fe-III氢氧化物中间体。到目前为止，尚未发现磁铁矿生物转化为GR的证据。在这项研究中，我们研究了一种铁还原细菌，腐败希万氏菌，在近中性的pH条件下，以二氢为唯一的无机电子供体还原磁铁矿的能力。在孕育过程中，GR和(或)菱铁矿((FeCO3)-C-II)以次生铁矿物的形式出现，这是由于磁铁矿中存在的Fe-III物种被细菌还原而产生的Fe-II物种的沉淀。考虑到次生铁矿物的确切性质和电子给体来源，是了解磁铁矿生物转化为GR的作用特性所必需的，迄今为止，这种转化被认为在近中性的pH下热力学上是不利的。这一发现强化了GR将是铁的缺氧生物地球化学循环中含铁矿物微生物转化的基石的假设，并为解释地球历史的演化和理解应用科学领域的生物腐蚀过程开辟了新的可能性。
Magnetite ((FeFe2O4)-Fe-II-O-III) is often considered as a stable end product of the bioreduction of Fe-III minerals (e.g., ferrihydrite, lepidocrocite, hematite) or of the biological oxidation of Fe-II compounds (e.g., siderite), with green rust (GR) as a mixed Fe-II-Fe-III hydroxide intermediate. Until now, the biotic transformation of magnetite to GR has not been evidenced. In this study, we investigated the capability of an iron-reducing bacterium, Shewanella putrefaciens, to reduce magnetite at circumneutral pH in the presence of dihydrogen as sole inorganic electron donor. During incubation, GR and/or siderite ((FeCO3)-C-II) formation occurred as secondary iron minerals, resulting from the precipitation of Fe-II species produced via the bacterial reduction of Fe-III species present in magnetite. Taking into account the exact nature of the secondary iron minerals and the electron donor source is necessary to understand the exergonic character of the biotic transformation of magnetite to GR, which had been considered to date as thermodynamically unfavorable at circumneutral pH. This finding reinforces the hypothesis that GR would be the cornerstone of the microbial transformations of iron-bearing minerals in the anoxic biogeochemical cycle of iron and opens up new possibilities for the interpretation of the evolution of Earth's history and for the understanding of biocorrosion processes in the field of applied science.