Sustained generation of electricity by the spore-forming, Gram-positive, Desulfitobacterium hafniense strain DCB2
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Desulfitobacterium hafniense strain DCB2 generates electricity in microbial fuel cells (MFCs) when humic acids or the humate analog anthraquinone-2,6-disulfonate (AQDS) is added as an electron-carrying mediator. When utilizing formate as fuel, the Gram-positive, spore-forming bacterium generated up to 400 mW/m2 of cathode surface area in a single-chamber MFC with a platinum-containing air-fed cathode. Hydrogen, lactate, pyruvate, and ethanol supported electricity generation, but acetate, propionate, and butyrate did not. Scanning electron microscopy indicated that strain DCB2 colonized the surface of a current-generating anode but not of an unconnected electrode. The electricity was recovered fully within minutes after the exchange of the medium in the anode chamber and within a week after an exposure of a colonized anode to 90°C for 20 min. Of the six strains of Desulfitobacteria tested, all of which would reduce AQDS, only D. hafniense strain DCB2 continued to reduce AQDS and generate electricity for more than 24 h, indicating that reduction of the humate analog alone is insufficient to sustain electrode reduction.
KeywordsFuel Cell Microbial Fuel Cell Anode Chamber Shewanella Putrefaciens Desulfitobacterium
This research was supported with funds from the National Institutes of Environmental Health Sciences (grant ES012815-01) and National Aeronautics and Space Administration (grant 897-7557-223-2094553/01-0). The authors would like to thank Tom Shaak (United States Air Force) for the assistance in the monitoring of the fuel cells, Carol Moskos (MUSC) for the assistance and instruction on the operation of the SEM, and Steve Creager (Clemson University) for the technical advice on fuel cells.