Mitsunobu Satoshi, Zhu Ming, Takeichi Yasuo, Ohigashi Takuji, Suga Hiroki, Jinno Muneaki, Makita Hiroko, Sakata Masahiro, Ono Kanta, Mase Kazuhiko, Takahashi Yoshio
Department of Environmental Conservation, Graduate School of Agriculture, Ehime University.
Microbes Environ. 2016;31(1):63-9. doi: 10.1264/jsme2.ME15137. Epub 2016 Mar 5.
We herein investigated the mechanisms underlying the contact leaching process in pyrite bioleaching by Acidithiobacillus ferrooxidans using scanning transmission X-ray microscopy (STXM)-based C and Fe near edge X-ray absorption fine structure (NEXAFS) analyses. The C NEXAFS analysis directly showed that attached A. ferrooxidans produces polysaccharide-abundant extracellular polymeric substances (EPS) at the cell-pyrite interface. Furthermore, by combining the C and Fe NEXAFS results, we detected significant amounts of Fe(II), in addition to Fe(III), in the interfacial EPS at the cell-pyrite interface. A probable explanation for the Fe(II) in detected EPS is the leaching of Fe(II) from the pyrite. The detection of Fe(II) also indicates that Fe(III) resulting from pyrite oxidation may effectively function as an oxidizing agent for pyrite at the cell-pyrite interface. Thus, our results imply that a key role of Fe(III) in EPS, in addition to its previously described role in the electrostatic attachment of the cell to pyrite, is enhancing pyrite dissolution.
我们在此利用基于扫描透射X射线显微镜（STXM）的碳（C）和铁（Fe）近边X射线吸收精细结构（NEXAFS）分析，研究了氧化亚铁硫杆菌在黄铁矿生物浸出过程中接触浸出的潜在机制。碳NEXAFS分析直接表明，附着的氧化亚铁硫杆菌在细胞-黄铁矿界面产生富含多糖的胞外聚合物（EPS）。此外，通过结合碳和铁的NEXAFS结果，我们在细胞-黄铁矿界面的界面EPS中除了检测到大量的Fe(III)外，还检测到了大量的Fe(II)。检测到的EPS中Fe(II)的一个可能解释是黄铁矿中Fe(II)的浸出。Fe(II)的检测还表明，黄铁矿氧化产生的Fe(III)可能在细胞-黄铁矿界面有效地作为黄铁矿的氧化剂。因此，我们的结果表明，除了其先前描述的在细胞与黄铁矿静电附着中的作用外，EPS中Fe(III)的关键作用是增强黄铁矿的溶解。
