Microbial community dynamics in continuous microbial fuel cells fed with synthetic wastewater and pig slurry

• Exoelectrogenic microbial communities were determined by the type of substrate used.
• MFC performance was not affected by the addition of BES-Inh.
• BES-Inh shifted the Eubacterial community, rather than the methanogenic community.
• Six OTUs were considered as the bioanode core microbiome in both MFC systems.

Two-chambered microbial fuel cells (MFCs) operating with synthetic wastewater and pig slurry were assessed. Additionally, the use of 2-bromoethanesulfonate (BES-Inh) was studied. The synthetic wastewater-fed MFC (MFCSW) showed a maximum power density (PDmax) of 2138 mW m− 3, and the addition of BES-Inh (10 mM) did not show any improvement in its performance (PDmax = 2078 mW m− 3). When pig slurry was used as feed (MFCPS), PDmax increased up to 5623 mW m− 3. The microbial community composition was affected by the type of substrate used. While, Pseudomonadaceae and Clostridiaceae were the most representative families within the acetate-based medium, Flavobacteriaceae, Chitinophagaceae, Comamonadaceae and Nitrosomonadaceae were predominant when pig slurry was used as feed. Otherwise, only the Eubacterial microbial community composition was strongly modified when adding BES-Inh, thus leading to an enrichment of the Bacteroidetes phylum. Oppositely, the Archaeal community was less affected by the addition of BES-Inh, and Methanosarcina sp., arose as the predominant family in both situations. Despite all the differences in microbial communities, 6 operational taxonomic units (OTUs) belonging to Bacteroidetes (Porphyromonadaceae and Marinilabiaceae) and Firmicutes (Clostridiales) were found to be common to both MFCs, also for different contents of COD and N-NH4+, and therefore could be considered as the bioanode core microbiome.

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