Characterization of microbial communities during anode biofilm reformation in a two-chambered microbial electrolysis cell (MEC)

GeoChip (II) and single strand conformation polymorphism (SSCP) were used to characterize anode microbial communities of a microbial electrolysis cell (MEC). Biofilm communities, enriched in a two-chamber MEC (R1, 0.6 V applied) having a coulombic efficiency (CE) of 35 ± 4% and a hydrogen yield (YH2)(YH2) of 31 ± 3%, were used as the inoculum for a new reactor (R2). After three months R2 achieved stable performance with CE = 38 ± 4% and YH2=31±7%.YH2=31±7%. Few changes in the predominant populations were observed from R1 to R2. Unlike sludge inoculation process in R1 in the beginning, little further elimination was aroused by community competitions in anode biofilm reformation in R2. Functional genes detection of biofilm indicated that cytochrome genes enriched soon in new reactor R2, and four genera (Desulfovibrio, Rhodopseudomonas, Shewanella and Geobacter) were likely to contribute to exoelectrogenic activity. This work also implied that symbiosis of microbial communities (exoelectrogens and others) contribute to system performance and stability.

► We studied anodic microbial community changes in a bioelectrochemcial system.
► New reactor were inoculated by biofilm communities and started up soon on performance.
► Exoelectrogens did not overwhelm other communities during biofilm reformation.
► A part of other functional communities potentially contributed to electron transport.
► Coulombic efficiency slightly increased and explained by increased cytochrome genes.