Carbon nanoparticles-assisted mediator-less microbial fuel cells using Proteus vulgaris

Recently mediator-less microbial fuel cells (MFCs) are attracting great interest among researchers due to their potential applications to electricity generation as well as wastewater treatment. Common mediator-less MFCs employ electroactive bacteria called exoelectrogens to directly transfer electrons to the anode from the bacteria. However, exoelectrogens are rather limited in number and thus may not find general use for practical purposes. Here we showed our results in which mediator-less MFCs could be developed from Gram-negative non-exoelectrogens. By using carbon nanoparticles as a conductive medium to immobilize bacteria, it was possible to generate appreciable electricity from Proteus vulgaris without exogenous mediators. Maximum power density of 269 mW m(-2) and cell voltage of ca. 400 mV were obtained using glucose as a substrate. Power generation was attributed to direct electron transfer and to self-produced mediators, both of which were assisted by carbon nanoparticles. Bacillus subtilis, a Gram-positive bacterium, in the meantime, did not produce appreciable electricity.