Magnetite from magnetotactic bacteria:: Size distributions and twinning
Magnetite from magnetotactic bacteria:: Size distributions and twinning
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DOI：
10.2138/am-1998-11-1228
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发表时间：
1998-11-01
影响因子：
3.1
通讯作者：
Buseck, PR
中科院分区：
文献类型：
--
作者：
Devouard, B;Pósfai, M;Buseck, PR
我们研究了几种形态的趋磁细菌产生的细胞内磁铁矿颗粒，包括螺旋形(螺旋形)淡水物种，磁性螺杆菌，以及四个不完全特征的海洋菌株：弯曲杆状细菌MV-1，两个球形(球形)微生物MC-1和MC-2，以及螺旋菌MV-4。用常规和高分辨率的电子显微镜观察了颗粒的形貌、尺寸分布和结构特征。不同的菌株产生具有独特形状的晶体。所有习惯都可以从等轴测的{111}、{110}和{100}形式的各种组合中衍生出来。我们比较了趋磁细菌晶体的大小和形状分布与大小相似的合成磁铁矿颗粒的大小和形状分布，发现生物和合成的分布在统计上是可区分的。特别是，细菌磁铁矿晶体的粒度分布较窄，并且具有与非生物样品相反的分布不对称性。细菌磁铁矿中唯一偏离理想结构的似乎是尖晶石孪晶的出现。还观察到稀疏的多胞胎。由于合成的磁铁矿晶体含有与细菌相似的孪晶，在没有特征晶链的情况下，只有大小和形状分布似乎有助于区分细菌和非生物成因的磁铁矿。
We studied intracellular magnetite particles produced by several morphological types of magnetotactic bacteria including the spirillar (helical) freshwater species, Magnetospirillum magnetotacticum, and four incompletely characterized marine strains: MV-1, a curved rod-shaped bacterium; MC-1 and MC-2, two coccoid (spherical) microorganisms; and MV-4, a spirillum. Particle morphologies, size distributions, and structural features were examined using conventional and high-resolution transmission electron microscopy. The various strains produce crystals with characteristic shapes. All habits can be derived from various combinations of the isometric {111}, {110}, and {100} forms. We compared the size and shape distributions of crystals from magnetotactic bacteria with those of synthetic magnetite grains of similar size and found the biogenic and synthetic distributions to be statistically distinguishable. In particular, the size distributions of the bacterial magnetite crystals are narrower and have a distribution asymmetry that is the opposite of the nonbiogenic sample. The only deviation from ideal structure in the bacterial magnetite seems to be the occurrence of spinel-law twins. Sparse multiple twins were also observed. Because the synthetic magnetite crystals contain twins similar to those in bacteria, in the absence of characteristic chains of crystals, only the size and shape distributions seem to be useful for distinguishing bacterial from nonbiogenic magnetite.