School of Metallurgy and Environment, Central South University, Changsha, 410083, China.
School of Metallurgy and Environment, Central South University, Changsha, 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha, 410083, China; Water Pollution Control Technology Key Lab of Hunan Province, Changsha, 410083, China.
Chemosphere. 2020 Jun;248:126080. doi: 10.1016/j.chemosphere.2020.126080. Epub 2020 Feb 1.
Tooeleite (Fe(AsO)(SO)(OH)·4HO), the only known ferric arsenite sulfate bearing mineral, has great potential for arsenic remediation due to its structure favoring incorporation of As(III). Based on the natural attenuation of removing As(III) directly by the formation of tooeleite via microorganisms, an iron-oxidizing bacterial strain Acidithiobacillus ferrooxidans ATCC 23270 (At.ferrooxidans) was selected to facilitate the formation of tooeleite. The optimized condition for the biogenic tooeleite was obtained at pH of 2.0, 30 °C and an initial arsenic of 500 mg/L. The process of biological mineralization is accompanied by the removal of 95.4% arsenic. What's more, biosynthetic tooeleite crystallization via a three-stage process was revealed using a combination of liquid and solid analyses (ICP-OES, XRD, XPS, FT-IR, SEM, STEM, particle distribution). The three stages included Fe oxidation by At.ferrooxidans, Fe hydrolysis and an initial Fe-As amorphous precursors formation, and finally transforming to tooeleite crystal. Moreover, RT-qPCR was used to reveal the relationship between functional gene expression of At.ferrooxidans and the mineral formation. The results showed the biogenic tooeleite exerts significant control on the geochemistry of arsenic contaminated systems.
太傲石（Fe(AsO)(SO)(OH)·4H₂O）是唯一已知的含砷的高铁亚硫酸盐矿物，由于其结构有利于砷（III）的掺入，因此具有很大的砷修复潜力。基于微生物通过形成太傲石直接自然衰减去除砷（III）的原理，选择了一种铁氧化细菌菌株 Acidithiobacillus ferrooxidans ATCC 23270（At.ferrooxidans）来促进太傲石的形成。在 pH 值为 2.0、30°C 和初始砷浓度为 500mg/L 的条件下，获得了生物成因太傲石的最佳条件。生物矿化过程伴随着 95.4%的砷去除。更重要的是，通过液体和固体分析（ICP-OES、XRD、XPS、FT-IR、SEM、STEM、颗粒分布）的结合，揭示了通过三阶段过程生物合成太傲石的结晶过程。三个阶段包括 At.ferrooxidans 氧化铁、铁水解和初始 Fe-As 无定形前体的形成，最后转化为太傲石晶体。此外，还使用 RT-qPCR 揭示了 At.ferrooxidans 功能基因表达与矿物形成之间的关系。结果表明，生物成因的太傲石对砷污染系统的地球化学具有显著的控制作用。
