Formation of tabular single-domain magnetite induced by Geobacter metallireducens GS-15.
Formation of tabular single-domain magnetite induced by Geobacter metallireducens GS-15.
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DOI：
10.1073/pnas.0404040101
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发表时间：
2004-11
影响因子：
11.1
通讯作者：
H. Vali;B. Weiss;Yiliang Li;S. Sears;S. Kim;J. Kirschvink;Chuanlun Zhang
中科院分区：
文献类型：
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作者：
H. Vali;B. Weiss;Yiliang Li;S. Sears;S. Kim;J. Kirschvink;Chuanlun Zhang
由磁性细菌（磁小体）在细胞内形成的磁铁矿的独特形态特征被用作地球上甚至可能在火星上生物活动的令人信服的证据。然而，传统上认为由金属还原地杆菌 GS-15、嗜热细菌和耐冷细菌等多种细菌在细胞外产生的磁铁矿晶体不具有几乎如此独特的形态。细胞外磁铁矿的大小和形状取决于细菌的培养条件和类型。在典型的富含 CO(2) 的培养条件下，已知 GS-15 会产生超顺磁性磁铁矿（晶体直径约为 <30 nm）。在当前的研究中，我们能够在非传统（低CO(2)）培养条件下生产出一种独特形式的板状单域磁铁矿。这种磁铁矿具有独特的晶体习性和磁性。这种磁铁矿可以用作生物特征来识别陆地和地外环境中的古代生物活动，也可能是天然沉积物中磁化强度的主要载体。
Distinct morphological characteristics of magnetite formed intracellularly by magnetic bacteria (magnetosome) are invoked as compelling evidence for biological activity on Earth and possibly on Mars. Crystals of magnetite produced extracellularly by a variety of bacteria including Geobacter metallireducens GS-15, thermophilic bacteria, and psychrotolerant bacteria are, however, traditionally not thought to have nearly as distinct morphologies. The size and shape of extracellular magnetite depend on the culture conditions and type of bacteria. Under typical CO(2)-rich culture conditions, GS-15 is known to produce superparamagnetic magnetite (crystal diameters of approximately <30 nm). In the current study, we were able to produce a unique form of tabular, single-domain magnetite under nontraditional (low-CO(2)) culture conditions. This magnetite has a distinct crystal habit and magnetic properties. This magnetite could be used as a biosignature to recognize ancient biological activities in terrestrial and extraterrestrial environments and also may be a major carrier of the magnetization in natural sediments.