Microbial community analysis in a long-term membrane-less microbial electrolysis cell with hydrogen and methane production

© 2015 Elsevier B.V. A single-chamber microbial electrolysis cell (MEC) aiming at hydrogen production with acetate as sole carbon source failed due to methanogenesis build-up despite the significant amount of 2-bromoethanesulfonate (BES) dosage, 50 mM. Specific batch experiments and a thorough microbial community analysis, pyrosequencing and qPCR, of cathode, anode and medium were performed to understand these observations. The experimental data rebuts different hypothesis and shows thatmethanogenesis at high BES concentration was likely due to the capacity of some Archaea (hydrogen-oxidizing genus Methanobrevibacter) to resist high BES concentration up to 200mM. Methanobrevibacter, of theMethanobacteriales order, represented almost the 98% of the total Archaea in the cathodewhereas Geobacterwas highly abundant in the anode (72% of bacteria).Moreover, at higher BES concentration (up to 200mM), methanogenesis activity decreased resulting in an increase of homoacetogenic activity, which challenged the performance of the MEC for H2 production.