Increase of riboflavin biosynthesis underlies enhancement of extracellular electron transfer of Shewanella in alkaline microbial fuel cells

• Published in: Bioresource technology 2013-02, Vol.130, p.763-768
• Main Authors: Yong, Yang-Chun, Cai, Zhao, Yu, Yang-Yang, Chen, Peng, Jiang, Rongrong, Cao, Bin, Sun, Jian-Zhong, Wang, Jing-Yuan, Song, Hao
• Format: Article
• Language: English
• Subjects: Biochemical fuel cells; Bioelectric Energy Sources; Biofuel production; Biological and medical sciences; Biosynthesis; Biotechnology; Electricity; Electrolytes; Electron transfer; Electron Transport; Energy; Extracellular electron transfer; Fuel cells; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Industrial applications and implications. Economical aspects; Microbial fuel cells; Microorganisms; Riboflavin; Riboflavin - biosynthesis; Shewanella; Shewanella - metabolism; Shewanella oneidensis
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2012.11.145

[Display omitted] ► Shewanella delivers the highest power output at pH=9. ► Shewanella synthesizes 0.6 times higher level of riboflavin at pH=9 than 7. ► Increased riboflavin synthesis underlies enhanced electron transfer in Shewanella. Electrolyte pH tremendously affects the electricity output of microbial fuel cells. However, its underlying molecular mechanism remains elusive, in particular for Shewanella oneidensis MR-1, one of the most widely adopted electrogenic microorganisms. Herein, we found that MFCs were able to deliver a significant (but different) electricity output in a wide range of pH (from 6 to 10), with the maximum at pH=9 (alkaline), which delivers ∼1.5times’ higher power output than that at pH=7 (neutral). Furthermore, cyclic voltammetry analysis showed an enhanced electrochemical activity of riboflavin (responsible for extracellular electron transfer of Shewanella) at alkaline pH. Strikingly, the concentration of riboflavin synthesized by Shewanella in MFCs at different pH showed a good correlation with the electricity output of MFCs. Thus, our results substantiated that the increase of riboflavin biosynthesis by Shewanella at the alkaline condition underlies the improvement of the electricity output in MFCs.