title: Protons accumulation during anodic phase turned to advantage for oxygen reduction during cathodic phase in reversible bioelectrodes.
abstract: Reversible bioelectrodes were designed by alternating acetate and oxygen supply. It was demonstrated that the protons produced and accumulated inside the biofilm during the anodic phase greatly favored the oxygen reduction reaction when the electrode was switched to become the biocathode. Protons accumulation, which hindered the bioanode operation, thus became an advantage for the biocathode. The bioanodes, formed from garden compost leachate under constant polarization at -0.2 V vs. SCE, were able to support long exposure to forced aeration, with only a slight alteration of their anodic efficiency. They produced a current density of 16±1.7 A/m2 for acetate oxidation and up to -0.4 A/m2 for oxygen reduction. Analysis of the microbial communities by 16S rRNA pyrosequencing revealed strong selection of Chloroflexi (49±1%), which was not observed for conventional bioanodes not exposed to oxygen. Chloroflexi were found as the dominant phylum of electroactive biofilms for the first time.
authors.affiliation: Laboratoire de Génie Chimique (LGC), CNRS, Université de Toulouse (INPT), 4 allée Emile Monso, BP 84234, 31432 Toulouse, France. Electronic address: blanchet.elise@gmail.com.
authors.forename: Elise
authors.initials: E
authors.lastname: Blanchet
authors.affiliation: Laboratoire de Génie Chimique, BioSym Department, Université de Toulouse, 35 chemin des Maraîchers, 31062 Toulouse, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Pécastaings
authors.affiliation: Laboratoire de Génie Chimique (LGC), CNRS, Université de Toulouse (INPT), 4 allée Emile Monso, BP 84234, 31432 Toulouse, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Erable
authors.affiliation: Laboratoire de Génie Chimique, BioSym Department, Université de Toulouse, 35 chemin des Maraîchers, 31062 Toulouse, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Roques
authors.affiliation: Laboratoire de Génie Chimique (LGC), CNRS, Université de Toulouse (INPT), 4 allée Emile Monso, BP 84234, 31432 Toulouse, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Bergel
mesh_terms: D002384:Catalysis; D004566:Electrodes; D064307:Microbiota; D010100:Oxygen / Q000737:chemistry*; D011522:Protons
chemical_list: D011522:Protons; D010100:Oxygen
keywords: Biocathode; Chloroflexi; Microbial fuel cell; Oxygen reduction; Reversible electrode