title: Analysis of the microbial community of the biocathode of a hydrogen-producing microbial electrolysis cell.
abstract: The microbial electrolysis cell (MEC) is a promising system for hydrogen production. Still, expensive catalysts such as platinum are needed for efficient hydrogen evolution at the cathode. Recently, the possibility to use a biocathode as an alternative for platinum was shown. The microorganisms involved in hydrogen evolution in such systems are not yet identified. We analyzed the microbial community of a mixed culture biocathode that was enriched in an MEC bioanode. This biocathode produced 1.1 A m(-2) and 0.63 m3 H2 m(-3) cathode liquid volume per day. The bacterial population consisted of 46% Proteobacteria, 25% Firmicutes, 17% Bacteroidetes, and 12% related to other phyla. The dominant ribotype belonged to the species Desulfovibrio vulgaris. The second major ribotype cluster constituted a novel taxonomic group at the genus level, clustering within uncultured Firmicutes. The third cluster belonged to uncultured Bacteroidetes and grouped in a taxonomic group from which only clones were described before; most of these clones originated from soil samples. The identified novel taxonomic groups developed under environmentally unusual conditions, and this may point to properties that have not been considered before. A pure culture of Desulfovibrio strain G11 inoculated in a cathode of an MEC led to a current development from 0.17 to 0.76 A m(-2) in 9 days, and hydrogen gas formation was observed. On the basis of the known characteristics of Desulfovibrio spp., including its ability to produce hydrogen, we propose a mechanism for hydrogen evolution through Desulfovibrio spp. in a biocathode system.
authors: Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB, Wageningen, The Netherlands. Elsemiek.Croese@wetsus.nl
authors: Elsemiek
authors: E
authors: Croese
authors: Maria Alcina
authors: MA
authors: Pereira
authors: Gert-Jan W
authors: GJ
authors: Euverink
authors: Alfons J M
authors: AJ
authors: Stams
authors: Jeanine S
authors: JS
authors: Geelhoed
mesh_terms: D001419:Bacteria / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification* / Q000378:metabolism*; D001674:Bioelectric Energy Sources / Q000382:microbiology*; D019149:Bioreactors / Q000382:microbiology; D004566:Electrodes / Q000382:microbiology; D004572:Electrolysis; D006859:Hydrogen / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny
chemical_list: D006859:Hydrogen