Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, Germany.
Environ Sci Technol. 2010 Jan 1;44(1):94-101. doi: 10.1021/es900708s.
More than 100 million individuals worldwide are exposed to arsenic-contaminated water, making the investigation of arsenic mobility in aquatic systems of utmost importance. Iron (hydr)oxides play a key role in preventing arsenic release in aquifers and soils due to their strong arsenic sorption and are even used to remove arsenic in water treatment. Neutrophilic Fe(II)-oxidizing bacteria produce Fe(III) minerals and therefore have the potential to affect arsenic mobility. In the present study, we demonstrate that the metabolism of anaerobic nitrate-reducing and phototrophic Fe(II)-oxidizing bacteria is not significantly affected by arsenate concentrations of up to 500 muM (37.5 mg/L). Even in the presence of the more toxic arsenic species, arsenite, cell metabolism was significantly impaired only at the highest arsenite concentration (500 muM) for one of the Fe(II)-oxidizers. All Fe(II)-oxidizing bacteria tested effectively immobilized arsenic during Fe(II) oxidation (>96%), lowering the remaining dissolved arsenic concentrations to values close to or even lower than the current drinking water limit of 10 microg/L. Since the minerals formed by these bacteria included highly crystalline Fe(III) minerals that are hardly reducible by Fe(III)-reducing bacteria, stimulation of arsenic immobilization by Fe(II)-oxidizing bacteria can potentially support water treatment systems or even be applied as an effective remediation strategy.
全球有超过 1 亿人接触到受砷污染的水，因此调查水生系统中砷的迁移性至关重要。由于铁（氢）氧化物对砷具有很强的吸附能力，因此在含水层和土壤中可防止砷释放，它们甚至被用于水的除砷处理。嗜中性的 Fe(II)氧化细菌会产生 Fe(III)矿物，因此有可能影响砷的迁移性。在本研究中，我们证明，在高达 500 μM（37.5 mg/L）的砷酸盐浓度下，厌氧硝酸盐还原菌和光养 Fe(II)氧化菌的代谢不受显著影响。即使存在毒性更强的砷物种亚砷酸盐，也只有在 Fe(II)氧化菌之一的最高亚砷酸盐浓度（500 μM）下，细胞代谢才会受到显著抑制。所有测试的 Fe(II)氧化菌在 Fe(II)氧化过程中都有效地固定砷（>96%），将剩余的溶解砷浓度降低到接近甚至低于当前饮用水限值 10μg/L 的水平。由于这些细菌形成的矿物包括高度结晶的 Fe(III)矿物，这些矿物几乎不会被 Fe(III)还原菌还原，因此 Fe(II)氧化菌对砷固定的刺激可能会支持水处理系统，甚至可以作为一种有效的修复策略。
