State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China.
Geobiology. 2012 Mar;10(2):150-62. doi: 10.1111/j.1472-4669.2011.00307.x. Epub 2011 Nov 10.
Clay minerals are ubiquitous in soils, sediments, and sedimentary rocks and could coexist with sulfate-reducing bacteria (SRB) in anoxic environments, however, the interactions of clay minerals and SRB are not well understood. The objective of this study was to understand the reduction rate and capacity of structural Fe(III) in dioctahedral clay minerals by a mesophilic SRB, Desulfovibrio vulgaris and the potential role in catalyzing smectite illitization. Bioreduction experiments were performed in batch systems, where four different clay minerals (nontronite NAu-2, mixed-layer illite-smectite RAr-1 and ISCz-1, and illite IMt-1) were exposed to D. vulgaris in a non-growth medium with and without anthraquinone-2,6-disulfonate (AQDS) and sulfate. Our results demonstrated that D. vulgaris was able to reduce structural Fe(III) in these clay minerals, and AQDS enhanced the reduction rate and extent. In the presence of AQDS, sulfate had little effect on Fe(III) bioreduction. In the absence of AQDS, sulfate increased the reduction rate and capacity, suggesting that sulfide produced during sulfate reduction reacted with the phyllosilicate Fe(III). The extent of bioreduction of structural Fe(III) in the clay minerals was positively correlated with the percentage of smectite and mineral surface area of these minerals. X-ray diffraction, and scanning and transmission electron microscopy results confirmed formation of illite after bioreduction. These data collectively showed that D. vulgaris could promote smectite illitization through reduction of structural Fe(III) in clay minerals.
粘土矿物在土壤、沉积物和沉积岩中普遍存在，并且可以在缺氧环境中与硫酸盐还原菌（SRB）共存，然而，粘土矿物与 SRB 的相互作用尚不清楚。本研究的目的是了解中温硫酸盐还原菌（Desulfovibrio vulgaris）对二八面体粘土矿物结构 Fe(III)的还原速率和还原容量，以及其在催化蒙脱石伊利石化过程中的潜在作用。在批处理系统中进行了生物还原实验，其中四种不同的粘土矿物（非钠蒙脱石 NAu-2、混层伊利石-蒙脱石 RAr-1 和 ISCz-1 以及伊利石 IMt-1）在非生长培养基中与 D. vulgaris 接触，同时有无蒽醌-2,6-二磺酸钠（AQDS）和硫酸盐。结果表明，D. vulgaris 能够还原这些粘土矿物中的结构 Fe(III)，AQDS 增强了还原速率和程度。在 AQDS 的存在下，硫酸盐对 Fe(III)的生物还原几乎没有影响。在没有 AQDS 的情况下，硫酸盐增加了还原速率和容量，这表明硫酸盐还原过程中产生的硫化物与层状硅酸盐 Fe(III)发生反应。粘土矿物中结构 Fe(III)的生物还原程度与这些矿物中蒙脱石的百分比和矿物表面积呈正相关。X 射线衍射、扫描和透射电子显微镜结果证实了生物还原后伊利石的形成。这些数据共同表明，D. vulgaris 可以通过还原粘土矿物中的结构 Fe(III)来促进蒙脱石伊利石化。
