Flavin mononucleotide mediated electron pathway for microbial U(VI) reduction
Flavin mononucleotide mediated electron pathway for microbial U(VI) reduction
复制标题
DOI：
10.1039/c0cp00339e
复制
发表时间：
2010-01-01
影响因子：
3.3
通讯作者：
Tsujimura, Seiya
中科院分区：
文献类型：
--
作者：
Suzuki, Yoshinori;Kitatsuji, Yoshihiro;Tsujimura, Seiya
微生物还原U（VI）是地下环境中影响铀活动性的重要现象。阐明其迁移机理对铀迁移预测和环境修复具有重要意义。在这项研究中，我们研究了电子途径的U（VI）的还原介导的黄素单胞苷（FMN），这是由希瓦氏菌属物种分泌。采用循环伏安法（CV）和光电化学方法（OTTLE）研究了FMN与U（VI）之间的电子转移反应。在有和没有FMN的柠檬酸盐和Tris-HCl缓冲液中进行U（VI）的CV测量。一个稀缺的U（VI）的还原电流观察到的FMN的情况下。相反，在FMN的氧化还原电位下，在FMN的存在下观察到催化U（VI）还原电流。还原电流随着U（VI）浓度的增加而增加。通过使用OTTLE电池的光电化学分析，确认U的还原形式为U（IV）。结果表明，FMN在U（VI）电还原为U（IV）过程中起着介体的作用。此外，体内腐败希瓦氏菌对U（VI）的生物还原实验表明，FMN的加入加速了U（VI）的还原速率。这些结果表明，希瓦氏菌属物种的U（VI）的生物还原可以由细胞分泌的FMN催化。
Microbial reduction of U(VI) is an important phenomenon affecting uranium mobility in the subsurface environments. Elucidation of its mechanism is necessary for predicting uranium migration and for applying environmental remediation. In this study, we have examined the electron pathway for the U(VI) reduction mediated by flavin mononucleotide (FMN), which is secreted by Shewanella species. The cyclic voltammetry (CV) and photo-electrochemical methods with an optically transparent thin-layer electrode (OTTLE) cell were utilized in investigating in vitro the electron transfer reactions that take place between FMN and U(VI). The CV measurements of U(VI) were carried out in a citrate and Tris-HCl buffer both with and without FMN. A scarce U(VI) reduction current was observed in the absence of the FMN. To the contrary, a catalytic U(VI) reduction current was observed in the presence of FMN at the redox potential of the FMN. The reduction current increased with an increase in the concentration of the U(VI). The reduced form of the U was confirmed to be U(IV) by the photo-electrochemical analysis using the OTTLE cell. The results demonstrated that FMN acts as a mediator in the electro-reduction of U(VI) to U(IV). In addition, in vivo bio-reduction experiments on U(VI) with Shewanella putrefaciens revealed that the addition of FMN accelerated the reduction rate of U(VI). These results indicate that the bio-reduction of U(VI) by the Shewanella species can be catalyzed by FMN secreted from the cells.