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首页> 外文期刊>Applied Microbiology >Microbial Lithotrophic Oxidation of Structural Fe(II) in Biotite
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Microbial Lithotrophic Oxidation of Structural Fe(II) in Biotite

机译：黑云母中结构铁（II）的微生物岩溶氧化

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Microorganisms are known to participate in the weathering of primary phyllosilicate minerals through the production of organic ligands and acids and through the uptake of products of weathering. Here we show that the lithotrophic Fe(II)-oxidizing, nitrate-reducing enrichment culture described by Straub et al. (K. L. Straub, M. Benz, B. Schink, and F. Widdel, Appl. Environ. Microbiol. 62:1458–1460, 1996) can grow via oxidation of structural Fe(II) in biotite, a Fe(II)-rich trioctahedral mica found in granitic rocks. Oxidation of silt/clay-sized biotite particles was detected by a decrease in extractable Fe(II) content and simultaneous nitrate reduction. M?ssbauer spectroscopy confirmed structural Fe(II) oxidation. Approximately 1.5 × 10~(7) cells were produced per μmol of Fe(II) oxidized, in agreement with previous estimates of the growth yield of lithoautotrophic circumneutral-pH Fe(II)-oxidizing bacteria. Microbial oxidation of structural Fe(II) resulted in biotite alterations similar to those found in nature, including a decrease in the unit cell b dimension toward dioctahedral levels and Fe and K release. Structural Fe(II) oxidation may involve either direct enzymatic oxidation, followed by solid-state mineral transformation, or indirect oxidation as a result of the formation of aqueous Fe, followed by electron transfer from Fe(II) in the mineral to Fe(III) in solution. Although it is not possible to distinguish between these two mechanisms with available data, the complete absence of aqueous Fe in oxidation experiments favors the former alternative. The demonstration of microbial oxidation of structural Fe(II) suggests that microorganisms are directly responsible for the initial step in the weathering of biotite in granitic aquifers and the plant rhizosphere.
机译：已知微生物通过产生有机配体和酸以及通过吸收风化产物而参与主要的层状硅酸盐矿物的风化。在这里，我们显示了Straub等人描述的岩溶性Fe（II）氧化，减少硝酸盐的富集培养。 （KL Straub，M. Benz，B. Schink和F.Widdel，Appl。Environ。Microbiol。62：1458-1460，1996）可以通过黑云母中结构性Fe（II）的氧化来生长，Fe（II）-花岗岩岩石中发现的丰富的八面体云母。通过减少可提取的Fe（II）含量并同时还原硝酸盐，可以检测出淤泥/粘土大小的黑云母颗粒的氧化。 Msssbauer光谱证实了Fe（II）的结构氧化。每μmol氧化的Fe（II）产生约1.5×10〜（7）个细胞，这与先前对自养营养性环境pH pH Fe（II）氧化细菌的生长产量的估计一致。结构性Fe（II）的微生物氧化导致黑云母蚀变，类似于自然界中发现的变化，包括单位细胞b朝着二八面体水平的减小以及Fe和K的释放。 Fe（II）的结构性氧化可能涉及直接酶促氧化，然后进行固态矿物转化，或者由于形成Fe水溶液而间接氧化，然后将电子从矿物中的Fe（II）转移到Fe（III） ）。尽管无法利用现有数据来区分这两种机理，但氧化实验中完全不存在含水铁，有利于采用前者。结构性Fe（II）的微生物氧化表明，微生物直接导致花岗岩含水层和植物根际中黑云母风化的初始步骤。

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