title: Biocathodes reducing oxygen at high potential select biofilms dominated by Ectothiorhodospiraceae populations harboring a specific association of genes.
abstract: Biocathodes polarized at high potential are promising for enhancing Microbial Fuel Cell performances but the microbes and genes involved remain poorly documented. Here, two sets of five oxygen-reducing biocathodes were formed at two potentials (-0.4V and +0.1V vs. saturated calomel electrode) and analyzed combining electrochemical and metagenomic approaches. Slower start-up but higher current densities were observed at high potential and a distinctive peak increasing over time was recorded on cyclic voltamogramms, suggesting the growth of oxygen reducing microbes. 16S pyrotag sequencing showed the enrichment of two operational taxonomic units (OTUs) affiliated to Ectothiorodospiraceae on high potential electrodes with the best performances. Shotgun metagenome sequencing and a newly developed method for the identification of Taxon Specific Gene Annotations (TSGA) revealed Ectothiorhodospiraceae specific genes possibly involved in electron transfer and in autotrophic growth. These results give interesting insights into the genetic features underlying the selection of efficient oxygen reducing microbes on biocathodes.
authors.affiliation: Irstea, UR HBAN, 1 rue Pierre-Gilles de Gennes, 92761 Antony cedex, France.
authors.forename: Elie
authors.initials: E
authors.lastname: Desmond-Le Quéméner
authors.affiliation: Laboratoire de Génie Chimique (LGC), CNRS, Université de Toulouse (INPT), 4 allée Emile Monso, BP 84234, 31432 Toulouse, France.
authors.forename: Mickaël
authors.initials: M
authors.lastname: Rimboud
authors.affiliation: Irstea, UR HBAN, 1 rue Pierre-Gilles de Gennes, 92761 Antony cedex, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Bridier
authors.affiliation: Irstea, UR HBAN, 1 rue Pierre-Gilles de Gennes, 92761 Antony cedex, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Madigou
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 (LGC), CNRS, Université de Toulouse (INPT), 4 allée Emile Monso, BP 84234, 31432 Toulouse, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Bergel
authors.affiliation: Irstea, UR HBAN, 1 rue Pierre-Gilles de Gennes, 92761 Antony cedex, France. Electronic address: theodore.bouchez@irstea.fr.
authors.forename: Théodore
authors.initials: T
authors.lastname: Bouchez
mesh_terms: D001674:Bioelectric Energy Sources; D018441:Biofilms; D042001:Ectothiorhodospiraceae / Q000235:genetics* / Q000254:growth & development; D055664:Electrochemical Techniques; D004566:Electrodes; D058977:Molecular Sequence Annotation; D058889:Molecular Typing; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D010802:Phylogeny; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D010100:Oxygen
keywords: Biocathode; Ectothiorodospiraceae; Metagenomics; Microbial Fuel Cells; Oxygen reduction reactions