Characterization and interactions of anodic isolates in microbial fuel cells explored for simultaneous electricity generation and Congo red decolorization

•Strains were isolated from MFCs for power production and azo dye decolorization.•Aquamicrobium was firstly reported as exoelectrogen and dye degrading bacterium.•Specific interaction could contribute to enhanced performance of MFCs. To investigate functions and interactions of predominant microorganisms in microbial fuel cells (MFCs) for simultaneous electricity generation and Congo red decolorization, four strains were isolated from the anodic biofilm, and identified as Pseudomonas (M-P and I-P), Bacillus (M-B) and Aquamicrobium (I-A). Higher maximum power density (by 158.2% and 58.1%) but lower Congo red decolorization rate (by 3.2% and 5.9%) were achieved in MFCs using pure cultures I-P and M-P as inoculums than those using I-A and M-B, respectively. By comparing MFCs using co-cultures with those using pure cultures (M-P&B versus M-B and M-P, I-P&A versus I-A and I-P), the maximum power density of MFCs using co-cultures increased 82.0%, 15.1%, 94.6% and −24.6% (minus meant decreased), but decolorization rate decreased 33.3%, 29.4%, 7.9% and 5.0%, respectively. The results indicated specific interaction could enhance the performance of MFCs and might benefit the development of bio-process controlling.