Mineral transformation associated with the microbial reduction of magnetite
Mineral transformation associated with the microbial reduction of magnetite
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DOI：
10.1016/s0009-2541(00)00210-2
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发表时间：
2000-09-01
期刊：
影响因子：
3.9
通讯作者：
Onstott, TC
中科院分区：
文献类型：
--
作者：
Dong, HL;Fredrickson, JK;Onstott, TC
虽然异化铁还原细菌(DIRB)能够以氧化物和可溶性形式还原许多金属，但控制磁铁矿还原速度/程度的因素和磁铁矿还原产生的矿物产品的性质尚不清楚。本研究旨在探讨腐败希瓦氏杆菌CN32和MR-1在还原磁铁矿过程中的作用机理和生物地球化学过程。用生物磁铁矿和合成磁铁矿在明确的溶液中进行了还原实验。生物磁铁矿是通过微生物还原水合氧化铁(HFO)而产生的。用含磷或不含磷的碳酸氢钠(HCO3-)或1，4-哌嗪二氢磺酸(PIPES)缓冲溶液中的生物磁铁矿接种菌株CN32，并以乳酸盐为电子供体。将人工合成的磁铁矿接种于细菌生长培养基(M1)中，分别接种CN32或MR-1菌株的需氧或厌氧生长的细胞。用HCl萃取法测定了生物还原样品和未接种对照样品的Fe(II)产量，并用X射线衍射仪(XRD)、穆斯堡尔谱、扫描和透射电子显微镜(SEM)和透射电子显微镜(TEM)对所得固体进行了表征。在碳酸氢盐缓冲介质中，生物产生的Fe(II)与HCO3-(或PO43-)络合，生成菱铁矿(蓝晶石)，从而使生物磁铁矿还原的程度和速率高于管式缓冲介质。S，腐生菌CN32还原合成磁铁矿多于生物成因磁铁矿，其差异主要归因于介质组成。在HCO3-缓冲溶液中，生物磁铁矿中的Fe(III)被还原为Fe(II)，生成菱铁矿。在管道缓冲介质中，生物磁铁矿中的Fe(III)也被还原为Fe(II)，但没有观察到次生矿物相。在那些含磷的溶液中和所有合成磁铁矿处理中形成了蓝晶石，在这些处理中，M1介质中有足够的磷供应。电子显微镜和穆斯堡尔谱结果表明，还原过程涉及溶解-沉淀机制，而不是将磁铁矿固相转化为蓝晶石或菱铁矿，水介质、pH、菌株类型和细菌生长条件都影响磁铁矿还原的程度。DREE利用结晶磁铁矿中的Fe(III)作为电子受体的能力可能对沉积物中的生物地球化学过程具有重要意义，因为磁铁矿中的Fe(III)是最大的电子受体池。(C)2000 Elsevier Science B.V.保留所有权利。
Although dissimilatory iron reducing bacteria (DIRB) are capable of reducing a number of metals in oxides and soluble forms, the factors controlling the rate/extent of magnetite reduction and the nature of the mineral products resulting from magnetite reduction are not well understood. This study was carried out to investigate mechanisms and biogeochemical processes occurring during magnetite reduction by the DIRE, Shewanella putrefaciens strains CN32 and MR-1. Reduction experiments were pel formed with biogenic and synthetic magnetite in well-defined solutions. Biogenic magnetite was generated via microbial reduction of hydrous ferric oxide (HFO). Biogenic magnetite in solutions buffered with either bicarbonate (HCO3-) or 1,4-piperazinedierhanesulfonic (PIPES), with or without P, was inoculated with strain CN32 and provided with lactate as the electron donor. Synthetic magnetite in a bacteriological growth medium (M1) was inoculated with either aerobically or anaerobically grown cells of strain (CN32 or MR-1). Fe(II) production was determined by HCl extraction of bioreduced samples in comparison to uninoculated controls, and the resulting solids were characterized by X-ray diffraction (XRD), Mossbauer spectroscopy, scanning and transmission electron microscopy (SEM and TEM). The extent and rate of biogenic magnetite reduction in the bicarbonate-buffered medium was higher than that in the PIPES-buffered medium, via complexation of bioproduced Fe(II) with HCO3- (or PO43-) and formation of siderite (vivianite). S, putrefaciens CN32 reduced more synthetic than biogenic magnetite with differences attributed mainly to medium composition. In the HCO3--buffered solutions, Fe(III) in the biogenic magnetite was reduced to Fe(II), and siderite precipitated. In the PIPES-buffered medium, Fe(III) in biogenic magnetite was also reduced to Fe(II), but no secondary mineral phases were observed. Vivianite formed in those solutions containing P and in all synthetic magnetite treatments where there was sufficient supply of P from the M1 medium. Electron microscopy and Mossbauer spectroscopy results suggest that the reduction process involves dissolution-precipitation mechanisms as opposed to solid state conversion of magnetite to vivianite or siderite, The aqueous medium, pH, strain type, and bacterial growth conditions all affected the extent of magnetite reduction. The ability of DIRE to utilize Fe(III) in crystalline magnetite as an electron acceptor could have significant implications for biogeochemical processes in sediments where Fe(III) in magnetite represents the largest pool of electron acceptor. (C) 2000 Elsevier Science B.V. All rights reserved.