Assisting the biofilm formation of exoelectrogens using nanostructured microbial fuel cells

Abstract

Exoelectrogens have drawn global concerns with their ability of spontaneous conversion of chemical energy into electrical energy. Thus, in the present study, nanostructured-microbial fuel cell systems, which are used for direct electron transfer via the anodic formed biofilm, were constructed. The impact of electrode materials on the selective capturing of exoelectrogens from mixed bacterial cultures was determined using cyclic voltammetry and mediatorless-microbial fuel cells. The electrochemical activities of the matured biofilm formed on the MnO2 modified electrode confirmed the direct electron transfer, whereas the outer redox species were involved in the extracellular electron transfer. Thus, efficient electrochemical signals were obtained and the optimized conditions have reached to maintain the viability of biofilm. Moreover, the morphological structures of the biofilms formed on the electrode surface were characterized by the scanning electron microscopy. From several mixed bacterial cultures, three exoelectrogenic strains were identified from the surface of the modified electrodes. Among the identified strains, Enterobacter cloacae DSM 30054 showed the highest electrochemical signals, while its electrocatalytic degradation of organic substrates and the productions of bioelectricity demonstrated the power density of 52.8 mW/m3 at 265.3 mA/m2 of current density.