Concurrent transformation of Ce(III) and formation of biogenic manganese oxides

微生物によるMn酸化物生成過程におけるCe(III)の化学状態変化

大貫 敏彦; 尾崎 卓郎; 香西 直文   ; 南川 卓也 ; 坂本 文徳  ; 酒井 卓郎; 鈴木 義規; Francis, A. J.*

Onuki, Toshihiko; Ozaki, Takuo; Kozai, Naofumi; Nankawa, Takuya; Sakamoto, Fuminori; Sakai, Takuro; Suzuki, Yoshinori; Francis, A. J.*

Mn酸化細菌によるMn(II)酸化過程におけるCe(III)の化学状態変化を微生物培養実験及びSEM, PIXE, XANES解析により検討した。その結果、Ce(III)は微生物細胞表面では酸化されず、Mn(II)が酸化されて生じたMn酸化物中でCe(IV)に酸化されることが明らかになった。

We examined the changes in the chemical states of Ce(III) during the formation of manganese oxide occasioned by Mn(II)-oxidizing bacteria. The oxidation states of Ce and Mn then were measured by X-ray Absorption Near Edge Structure (XANES). We also determined the elemental distributions in the bacteria and precipitates by Scanning-Proton Induced X-ray Emission (S-PIXE). We found that the precipitation of Ce is preceded by its accumulation by the bacterium, followed by its oxidization to Ce(IV) by the Mn(III, IV)-containing precipitates that the bacteria generate.