Electrochemical studies on microbial U(VI) reduction

Suzuki, Yoshinori; Onuki, Toshihiko

We investigated electrochemically the surface catalytic reduction of (VI) on Shewanella putrefaciens and the flavin mononucleotide (FMN) mediated extracellular reduction of U(VI). Using the cell containing membrane electrode, the cyclic voltammograms (CVs) were obtained at various U(VI) concentrations. In the absence of U(VI), reduction peak was hardly detected. In the presence of U(VI), a reduction peak was observed at -0.6 V and it increased with U(VI) concentration. These results indicate that the cell surfaces provide the site for catalytic reduction of U(VI). The CVs of FMN were obtained at various U(VI) concentrations by a normal Au electrode. In the presence of U(VI), the reduction peak increased and the oxidation peak decreased with a rise in the U(VI) concentration. These results indicate that FMN mediates the reduction of U(VI). In this study, we electrochemically confirmed the direct catalytic reduction on the cell surfaces and the FMN mediated reduction.