Environmental Hydrogeochemistry, Geological Survey of Spain (IGME), Madrid, Spain.
Department of Geological Resources, Geological Survey of Spain (IGME), Madrid, Spain.
Geobiology. 2018 Jan;16(1):88-103. doi: 10.1111/gbi.12269.
Through the use of scanning transmission electron microscopy (STEM) combined with other complementary techniques (SEM, cryo-TEM, HRTEM, and EELS), we have studied the interaction of microorganisms inhabiting deep anoxic waters of acidic pit lakes with dissolved aluminum, silica, sulfate, and ferrous iron. These elements were close to saturation (Al, SiO ) or present at very high concentrations (0.12 m Fe(II), 0.12-0.22 m SO ) in the studied systems. The anaerobic conditions of these environments allowed investigation of geomicrobial interactions that are difficult to see in oxidized, Fe(III)-rich environments. Detailed chemical maps and through-cell line scans suggest both extra- and intracellular accumulation of Al, Si, S, and Fe(II) in rod-like cells and other structures (e.g., spherical particles and bacteriomorphs) of probable microbial origin. The bacterial rods showed external nanometric coatings of adsorbed Fe(II) and Al on the cell surface and cell interiors with significant presence of Al, Si, and S. These microbial cells coexist with spherical particles showing similar configuration (Fe(II) external coatings and [Al, Si, S]-rich cores). The Al:Si and Al:S ratios and the good Al-Si correlation in the cell interiors suggest the concurrent formation of two amorphous phases, namely a proto-aluminosilicate with imogolite-like composition and proto-hydrobasaluminite. In both cases, the mineralization appears to comprise two stages: a first stage of aluminosilicate and Al-hydroxysulfate precipitation within the cell or around cellular exudates, and a second stage of SO and Fe(II) adsorption on surface sites existing on the mineral phases in the case of (SO ) or on presumed organic molecules [in the case of Fe(II)]. These microbially related solids could have been formed by permineralization and mineral replacement of senescent microbial cells. However, these features could also denote biomineralization by active bacterial cells as a detoxification mechanism, a possibility which should be further explored. We discuss the significance of the observed Al/microbe and Si/microbe interactions and the implications for clay mineral formation at low pH.
通过使用扫描透射电子显微镜（STEM）结合其他互补技术（SEM、低温 TEM、HRTEM 和 EELS），我们研究了栖息在酸性坑湖深部缺氧水中的微生物与溶解的铝、硅、硫酸盐和亚铁的相互作用。这些元素在研究系统中接近饱和（Al、SiO ）或浓度非常高（0.12 m Fe(II)，0.12-0.22 m SO ）。这些环境的厌氧条件允许研究在氧化的富 Fe(III)环境中难以看到的地球微生物相互作用。详细的化学图谱和细胞线扫描表明，在棒状细胞和其他结构（例如球形颗粒和细菌形态）中，铝、硅、硫和亚铁（II）既有细胞外积累，也有细胞内积累，这些结构可能具有微生物起源。细菌棒状细胞表面和细胞内部存在吸附的 Fe(II)和 Al 的纳米级涂层，并且存在大量的 Al、Si 和 S。这些微生物细胞与具有相似形态的球形颗粒共存（细胞外部的 Fe(II)涂层和[Al、Si、S]-丰富的核心）。细胞内部的 Al:Si 和 Al:S 比值以及 Al-Si 的良好相关性表明同时形成了两种无定形相，即具有似蛋白石组成的原铝硅酸盐和原氢钡铝酸盐。在这两种情况下，矿化似乎包括两个阶段：第一阶段是在细胞内或细胞渗出物周围沉淀铝硅酸盐和 Al-羟基硫酸盐，第二阶段是在矿物相中存在表面位点上吸附 SO 和 Fe(II)（对于（SO ））或假定的有机分子（对于 Fe(II)）。这些与微生物相关的固体可能是由衰老微生物细胞的矿化和矿物替代形成的。然而，这些特征也可能表示活性细菌细胞作为解毒机制的生物矿化，这是一个需要进一步探索的可能性。我们讨论了观察到的 Al/微生物和 Si/微生物相互作用的意义以及对低 pH 下粘土矿物形成的影响。
