期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 110, 期 19, 页码 7856-7861出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1220823110
关键词
iron-reducing bacteria; electromicrobiology; microbial fuel cell; whole-cell voltammetry; flavin mononucleotide
资金
- Japan Society for Promotion of Science for Young Scientists [00218864]
- Exploratory Research for Advanced Technology program of the Japan Science and Technology Agency
- Grants-in-Aid for Scientific Research [12J07550] Funding Source: KAKEN
Extracellular redox-active compounds, flavins and other quinones, have been hypothesized to play a major role in the delivery of electrons from cellular metabolic systems to extracellular insoluble substrates by a diffusion-based shuttling two-electron-transfer mechanism. Here we show that flavin molecules secreted by Shewanella oneidensis MR-1 enhance the ability of its outer-membrane c-type cytochromes (OM c-Cyts) to transport electrons as redox cofactors, but not free-form flavins. Whole-cell differential pulse voltammetry revealed that the redox potential of flavin was reversibly shifted more than 100 mV in a positive direction, in good agreement with increasing microbial current generation. Importantly, this flavin/OM c-Cyts interaction was found to facilitate a one-electron redox reaction via a semiquinone, resulting in a 10(3)- to 10(5)-fold faster reaction rate than that of free flavin. These results are not consistent with previously proposed redox-shuttling mechanisms but suggest that the flavin/OM c-Cyts interaction regulates the extent of extracellular electron transport coupled with intracellular metabolic activity.
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