Microbial community analysis in biocathode microbial fuel cells packed with different materials

Microbial fuel cells (MFCs) utilize microorganisms as catalysts, which can promote biodegradation of organic matters and simultaneously produce an electrical current (Bond et al. 2002). In the past few years, researchers generally use chemical cathode MFC to remove the organic carbon in wastewater, but the cost of chemical cathode is high and it is easily lead to pollution. Currently, biocathode MFCs using microorganisms instead of common Pt as catalysts have important advantages in lowering cost, expanding function and improving sustainability. Therefore, biocathode MFCs as a new economical and environmentally friendly wastewater treatment technology has drawn more and more attentions (Huang et al. 2011). Although biocathode MFCs have many advantages, the current studies are still at laboratory level. The main challenge for their large-scale application is low power generation capability. Microorganisms are the core of biocathode MFCs. In the anode, microorganisms attaching on the electrode material and forming biofilm play an essential role in MFC generating electricity (Rabaey and Rozendal 2010), and in the cathode, the microbial catalytic efficiency plays a key role to improve the cathode potential and power output (Osman et al. 2010). Therefore, better understanding of the ecology of the microbial communities in the different reactors will be helpful to improve MFCs power production.At present, the anodic microbes get more attention, including the electricity-producing bacteria species (Holmes et al. 2004Xia et al. 2010), anodic microbial community composition (Cárcer et al. 2011Jung and Regan 2010Kim et al. 2011Zhang et al. 2011), the mechanism of extracellular electron transfer (Carmona-Martinez et al. 2011Strycharz et al. 2011) and so on. In contrast, the researches on the microbes of biocathode MFCs are very limited, and mainly focused on the role of pure bacteria in biocathode MFCs. For instance, Carbajosa et al. (2010) found that an acidophilic Acidithiob