Enumeration of exoelectrogens in microbial fuel cell effluents fed acetate or wastewater substrates

Effluents from well-acclimated microbial fuel cells (MFCs) have been widely used as inocula to start up new MFC reactors. However, the actual cell concentrations and viability of exoelectrogens in these effluents not well examined. In this study, effluent acetate- or wastewater-fed MFCs were examined using a quantitative polymerase chain reaction (qPCR) method specific for Geobacter spp. that are usually dominant genus MFCs, non-specific WO3 nanocluster/most probable number (WO3/MPN) enumeration viable exoelectrogens. acetate-fed based on qPCR 1.3 ± 0.2 × 108 cells/mL, slightly higher than those (9.3 3.5 107 cells/mL). exoelectrogen counts WO3/MPN several orders magnitude lower both (1.1 0.3 104 cells/mL acetate-fed; 1.4 105 wastewater-fed). Live/dead staining suggested most (85 %) inactive dead, which could partly explain numbers method. These results suggest contain high although percentage viable.