| description |
Methanol is widely used in industrial processes as a fuel, solvent and raw chemical material, and large quantities are discharged into wastewaters. Although microbial fuel cells (MFCs) are expected as devices that recover electric energy from organic pollutants in wastewater, there has been no report demonstrating that electricity isgenerated from methanol in MFCs. In the present study, single-chamber MFCs were inoculated with activated sludge obtained from an industrial wastewater-treatment plant and fed methanol as the sole carbon and energy source. After operating the MFC for several months, electricity was generated from methanol with the maximum power density of 210 mW m-2 (based on an anode projection area) and Coulombic efficiency of 15%. An anode-replacement test indicated that electricity was mainly generated by anode-biofilm microbes. Bacterial communities in the anode biofilm, cathode biofilm and electrolyte were analyzed by pyrotag sequencing of 16S rRNA-gene PCR amplicons, showing that they were relatively similar and substantially different from that in the original activated sludge. Major genera commonly detected in these samples included Dysgonomonas, Sporomusa, and Desulfovibrio, while Geobacter was detected only in the anode biofilm. Results suggest a possibility that methanol was converted to electricity under a syntrophic association of Geobacter with Sporomusa. This idea was supported by Illumina shotgun metagenomic analyses of the anode-biofilm community, suggesting that the initial step in the methanol degradation is catalyzed by corrinoid-dependent methyltransferases harbored by Sporomusa. |