Time-resolved synchrotron powder X-ray diffraction study of magnetite formation by the Fe(III)-reducing bacterium Geobacter sulfurreducens
Time-resolved synchrotron powder X-ray diffraction study of magnetite formation by the Fe(III)-reducing bacterium Geobacter sulfurreducens
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DOI：
10.2138/am.2008.2467
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发表时间：
2008-04-01
影响因子：
3.1
通讯作者：
Lloyd, Jonathan R.
中科院分区：
文献类型：
--
作者：
Coker, Victoria S.;Bell, Anthony M. T.;Lloyd, Jonathan R.
Fe（III）还原菌Geophylsulfurreducens通过将电子从有机物或氢转移到水铁矿，导致水铁矿还原转化为磁铁矿，并产生用于生长的ATP，从而产生纳米尺寸的磁铁矿。电子转移可以通过细胞表面和矿物之间的直接接触或通过可溶性"电子穿梭"（例如含醌的腐殖物质）发生。使用高分辨率同步加速器粉末X射线衍射测量了两个实验（一个含有和一个不含腐殖酸类似物蒽醌-2，6-二磺酸盐（AQDS））中铁铁矿还原不同阶段产生的矿物。无定形双线水铁矿转化为针铁矿，然后转化为针铁矿和磁铁矿的混合物，最后转化为磁铁矿。有和没有AQDS的样品表现出相同的一般矿物学趋势，并且在AQDS的存在下反应速率更快。此外，两个瞬态矿物结构相似的针铁矿和磁铁矿被观察到形成的中间体之间的水铁矿和针铁矿和针铁矿和磁铁矿，但只有在样品中产生的电子穿梭的情况下。这些过渡矿物被称为原针铁矿和原磁铁矿。原始针铁矿的c轴[4.467（20）埃]比结晶针铁矿短，是尺寸的函数（
The Fe(III)-reducing bacterium Geobacter sulfurreducens produces nanometer-sized magnetite by transferring electrons from organic matter or hydrogen to ferrihydrite, resulting in the reductive transformation of the ferrihydrite to magnetite, and the generation of ATP for growth. Electron transfer can occur by direct contact between the cell surface and the mineral or via a soluble "electron shuttle," for example a quinone-containing humic species. The minerals produced at different stages of ferrihydrite reduction during two experiments, one with and one without the humic analog anthraquinone-2, 6-disulphonate (AQDS), were measured using high-resolution synchrotron powder X-ray diffraction. Amorphous 2-line ferrihydrite converts to goethite, then to a mixture of goethite and magnetite, and finally to magnetite. Samples with and without AQDS showed the same general mineralogical trends, and the rate of reaction was faster in the presence of AQDS. In addition, two transient minerals structurally similar to goethite and magnetite were observed to form as intermediates between ferrihydrite and goethite and goethite and magnetite, but only in samples produced in the absence of the electron shuttle. These transient minerals were named proto-goethite and proto-magnetite. Proto-goethite has a shorter c-axis [4.467(20) angstrom] than crystalline goethite, a function of size (