title: Direct determination of oxidation state of gold deposits in metal-reducing bacterium Shewanella algae using X-ray absorption near-edge structure spectroscopy (XANES).
abstract: X-ray absorption near-edge structure spectroscopy (XANES) was successfully employed to determine the gold valence in the metal-reducing bacterium Shewanella algae after exposure to a 1 mM aqueous HAuCl4 solution for 10-120 min. XANES spectra revealed the oxidation state of gold in the bacterial cells to be Au(0) without any contribution from Au(III), demonstrating that S. algae cells can reduce AuCl4- ions to elemental gold. Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis confirmed that gold nanoparticles 5-15 nm in size were deposited in the periplasmic space of the bacterial cells; a preferable, cell surface location for the easy recovery of biogenic nanoparticles.
authors.affiliation: Department of Chemical Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan. yasuhiro@chemeng.osakafu-u.ac.jp
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Konishi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tsukiyama
authors.forename: Norizoh
authors.initials: N
authors.lastname: Saitoh
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Nomura
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Nagamine
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Tomoya
authors.initials: T
authors.lastname: Uruga
mesh_terms: D006046:Gold / Q000378:metabolism*; D017612:Gold Compounds / Q000378:metabolism; D008854:Microscopy, Electron; D010084:Oxidation-Reduction; D020592:Shewanella / Q000378:metabolism* / Q000648:ultrastructure; D013057:Spectrum Analysis; D014965:X-Rays
chemical_list: D017612:Gold Compounds; C038016:gold chloride; D006046:Gold