title: Direct Detection of Fe(II) in Extracellular Polymeric Substances (EPS) at the Mineral-Microbe Interface in Bacterial Pyrite Leaching.
abstract: 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.
authors.affiliation: Department of Environmental Conservation, Graduate School of Agriculture, Ehime University.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mitsunobu
authors.forename: Ming
authors.initials: M
authors.lastname: Zhu
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Takeichi
authors.forename: Takuji
authors.initials: T
authors.lastname: Ohigashi
authors.forename: Hiroki
authors.initials: H
authors.lastname: Suga
authors.forename: Muneaki
authors.initials: M
authors.lastname: Jinno
authors.forename: Hiroko
authors.initials: H
authors.lastname: Makita
authors.forename: Masahiro
authors.initials: M
authors.lastname: Sakata
authors.forename: Kanta
authors.initials: K
authors.lastname: Ono
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Mase
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takahashi
mesh_terms: D042763:Acidithiobacillus / Q000378:metabolism*; D001704:Biopolymers / Q000737:chemistry* / Q000378:metabolism*; D004577:Electron Probe Microanalysis; D004783:Environmental Microbiology; D007501:Iron / Q000032:analysis* / Q000378:metabolism; D017348:Microscopy, Electron, Scanning Transmission; D010084:Oxidation-Reduction; D013440:Sulfides / Q000378:metabolism*
chemical_list: D001704:Biopolymers; D013440:Sulfides; C011342:pyrite; D007501:Iron