2-Bromoethanesulfonate degradation in bioelectrochemical systems.

2-Bromoethanesulfonate (BES) is the most reported chemical inhibitor for methanogenesis in laboratory-scale bioelectrochemical systems. However, there is doubt about BES's long-term effectiveness in microbial fuel cells (MFCs). We observed BES degradation in MFCs, whereas not in microbial electrolysis cells (MECs). Our results suggest that BES degradation is only possible under aerobic conditions (such as in MFCs) when some oxygen diffuses through the cathode. Experimental BES degradation was linked to the release of bromide (Br(-)) into the medium, with an average recovery of 67 ± 16%. Microbial analysis of the cathodic biomass distribution revealed the presence of Pseudomonas and Alcaligenes genera, which are able to use sulfonates as carbon or sulfur sources under aerobic conditions.