LIMOS (Laboratoire des Interactions Microorganismes-Minéraux-Matière Organique dans les Sols), UMR 7137 CNRS, BP 70239, Vandoeuvre-lès-Nancy Cedex 54506, France.
J Colloid Interface Sci. 2011 Oct 15;362(2):317-24. doi: 10.1016/j.jcis.2011.07.031. Epub 2011 Jul 20.
Four colloidal-size fractions of strongly anisotropic particles of nontronite (NAu-2) having different ratios of basal to edge surfaces were incubated in the presence of heterotrophic soil bacteria to evaluate how changes in mineral surface reactivity influence microbial dissolution rate of minerals. To avoid any particle aggregation, which could change the reactive surface area available for dissolution, NAu-2 particles were immobilized in a biocompatible TEOS-derived silica matrix. The resulting hybrid silica gels support bacterial growth with NAu-2 as the sole source of Fe and Mg. Upon incubation of the hybrid material with bacteria, between 0.3% and 7.5% of the total Fe included in the mineral lattice was released with a concomitant pH decrease. For a given pH value, the amount of released Fe varied between strains and was two to twelve-fold higher than under abiotic conditions. This indicates that complexing agents produced by bacteria play an important role in the dissolution process. However, in contrast with proton-promoted NAu-2 dissolution (abiotic incubations) that was negatively correlated with particle size, bacterial-enhanced dissolution was constant for all size fractions used. We conclude that bio-dissolution of nontronite particles under acidic conditions seems to be controlled by bacterial metabolism rather than by the surface reactivity of mineral.
四种不同基面与边缘比的强各向异性针铁矿（NAu-2）胶体颗粒在异养土壤细菌存在的情况下进行孵育，以评估矿物表面反应性的变化如何影响微生物对矿物的溶解速率。为了避免任何可能改变可用于溶解的反应表面积的颗粒聚集，将 NAu-2 颗粒固定在生物相容性的 TEOS 衍生的硅基质中。所得的混合硅胶凝胶支持以 NAu-2 为唯一铁和镁来源的细菌生长。在将混合材料与细菌一起孵育时，矿物晶格中包含的总铁的 0.3%至 7.5%被释放出来，同时 pH 值下降。对于给定的 pH 值，释放的铁的量在菌株之间变化，并且比非生物条件下高 2 到 12 倍。这表明细菌产生的配位剂在溶解过程中起重要作用。然而，与质子促进的 NAu-2 溶解（非生物孵育）呈负相关不同，细菌增强的溶解对于使用的所有颗粒大小均保持不变。我们得出结论，在酸性条件下，针铁矿颗粒的生物溶解似乎受细菌代谢而不是矿物表面反应性控制。
