title: Total solid content drives hydrogen production through microbial selection during thermophilic fermentation.
abstract: In this study, the effect of total solid content (TS) on thermophilic hydrogen production from wheat straw was investigated. Six TS contents ranging from wet to dry conditions (10-34%TS) were tested in batch tests. A decrease of H₂ yields was observed and three statistical groups were distinguished according to the TS content: wet conditions (10% and 14%TS) with 15.3 ± 1.6 NmlH₂ gTS(-1), intermediate conditions (19%TS) with 6.4 ± 1.0 NmlH₂ gTS(-1) and dry conditions (25-34%TS) with 3.4 ± 0.8 NmlH₂ gTS(-1). Such a decrease in biohydrogen yields was related to a metabolic shift with an accumulation of lactic acid under dry conditions. Concomitantly, a microbial population shift was observed with a dominance of species related to the class Clostridia under wet conditions, and a co-dominance of members of Bacilli, Clostridia classes and Bacteroidetes phylum under dry conditions.
authors.affiliation: INRA, UR0050, Laboratoire de Biotechnologie de l'Environnement, Avenue des Etangs, Narbonne F-11100, France.
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Motte
authors.affiliation: INRA, UR0050, Laboratoire de Biotechnologie de l'Environnement, Avenue des Etangs, Narbonne F-11100, France. Electronic address: eric.trably@supagro.inra.fr.
authors.forename: Eric
authors.initials: E
authors.lastname: Trably
authors.affiliation: INRA, UR0050, Laboratoire de Biotechnologie de l'Environnement, Avenue des Etangs, Narbonne F-11100, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Hamelin
authors.affiliation: INRA, UR0050, Laboratoire de Biotechnologie de l'Environnement, Avenue des Etangs, Narbonne F-11100, France.
authors.forename: Renaud
authors.initials: R
authors.lastname: Escudié
authors.affiliation: INRA, UR0050, Laboratoire de Biotechnologie de l'Environnement, Avenue des Etangs, Narbonne F-11100, France.
authors.forename: Anaïs
authors.initials: A
authors.lastname: Bonnafous
authors.affiliation: INRA, UR0050, Laboratoire de Biotechnologie de l'Environnement, Avenue des Etangs, Narbonne F-11100, France.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Steyer
authors.affiliation: INRA, UR0050, Laboratoire de Biotechnologie de l'Environnement, Avenue des Etangs, Narbonne F-11100, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bernet
authors.affiliation: INRA, UR0050, Laboratoire de Biotechnologie de l'Environnement, Avenue des Etangs, Narbonne F-11100, France.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Delgenès
authors.affiliation: INRA, UR0050, Laboratoire de Biotechnologie de l'Environnement, Avenue des Etangs, Narbonne F-11100, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Dumas
mesh_terms: D001419:Bacteria / Q000145:classification / Q000378:metabolism*; D056804:Biofuels; D019149:Bioreactors; D005285:Fermentation; D006859:Hydrogen / Q000378:metabolism*; D008031:Lignin / Q000378:metabolism*; D014908:Triticum / Q000737:chemistry*
chemical_list: D056804:Biofuels; C036909:lignocellulose; D006859:Hydrogen; D008031:Lignin
keywords: Biohydrogen; Dark fermentation; Lignocellulosic residues; Solid-state processes; hydA genes