Exploring microbial community in SMEC with two different wastewaters as electron donors

We operated a sandwich-type microbial electrolysis cell (SMEC) to explore its microbial community under two different electron donors: Acetate and wastewater. We investigated the microbial community using pyrosequencing, quantitative real time PCR (QPCR), and automatic ribosomal intergenic spacer analysis. 454 FLX Titanium pyrosequencing generated 9,752 and 14,428 sequences from anode biofilm samples of the SMEC fed by acetate and wastewater, respectively. We observed higher diversity in anode biofilm from the SMEC fed by wastewater, consisting of several major genera, Trichlorobacter, Desulfomicrobium, Desulfobacter, and Clostridium where the current density was 1.9 A/m ² (cathodic surface area: 36 cm ²). In contrast, genus Geobacter outcompeted this mixture of microbes and became the most dominant species (63% of total bacteria by QPCR) in the SMEC with acetate, where the current density increased to 38 A/m ². Several other genera of Pandoraea, Fusibacter, and Acinetobacter appeared as relatively abundant minor players and candidates of anode-respiring bacteria (ARB).