This study investigates the performance and microbial community of a single-chamber air-breathing microbial fuel cell (MFC) treating organic wastewater containing high sulfate under continuous operation. The chemical oxygen demand (COD) removal efficiencies of the MFC were 57 +/- 10.1%; while the sulfate removal efficiencies were relatively low 18 +/- 8.8%. The voltages of the system increased and remained stable for two weeks and then rapidly decreased. Replacement of the anode greatly improved the electricity generation of the MFC. The results from scanning electron microscopy with an energy dispersive X-ray (SEM-EDX) show that sulfur accumulated on the anode, which could explain the increases in ohmic loss of the MFC over time. Microbial community analysis using 16S rRNA gene amplicon sequencing revealed that sulfur-oxidizing bacteria (Thiobacillus spp.) were dominant on the anodic biofilm. On the other hand, sulfate-reducing bacteria in Desulfobacteraceae were dominant in suspended microorganisms at the end of MFC operation. (C) 2015 Elsevier Ltd. All rights reserved.