In order to gain insight into the significance of biotic metal reduction and mineral formation in hyperthermophilic environments, metal mineralization as a result of the dissimilatory reduction of poorly crystalline Fe(III) oxide, and U(VI) reduction at 100 degrees C by Pyrobaculum islandicum was investigated. When P. islandicum was grown in a medium with poorly crystalline Fe(III) oxide as an electron acceptor and hydrogen as an electron donor, the Fe(III) oxide was reduced to an extracellular, ultrafine-grained magnetite with characteristics similar to that found in some hot environments and that was previously thought to be of abiotic origin. Furthermore, cell suspensions of P. islandicum rapidly reduced the soluble and oxidized form of uranium, U(VI), to extracellular precipitates of the highly insoluble U(IV) mineral, uraninite (UO(2)). The reduction of U(VI) was dependent on the presence of hydrogen as the electron donor. These findings suggest that microbes may play a key role in metal deposition in hyperthermophilic environments and provide a plausible explanation for such phenomena as magnetite accumulation and formation of uranium deposits at ca. 100 degrees C.

中文翻译：

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Pyrobaculum islandicum在100摄氏度下异化Fe（III）和U（VI）还原过程中产生的细胞外矿物的表征。

为了深入了解在超高温环境中生物金属还原和矿物质形成的重要性，金属矿物的形成是结晶不良的Fe（III）氧化物异化还原的结果，而Pyrobaculum islandicum在100摄氏度下还原U（VI）被调查了。当P. islandicum在结晶度较差的Fe（III）作为电子受体和氢作为电子供体的介质中生长时，Fe（III）氧化物被还原为具有类似于所发现特征的胞外超细磁铁矿在某些高温环境中，以前被认为是非生物来源。此外，岛状疟原虫的细胞悬浮液迅速将铀U（VI）的可溶和氧化形式还原为高度不溶的U（IV）矿物尿素（UO（2））的细胞外沉淀物。U（VI）的还原取决于氢作为电子给体的存在。这些发现表明，微生物在高温环境中可能在金属沉积中起关键作用，并为诸如磁铁矿堆积和铀矿床形成铀等现象提供了合理的解释。100摄氏度