title: Semi-continuous methane production from undiluted brown algae using a halophilic marine microbial community.
abstract: Acclimated marine sediment-derived culture was used for semi-continuous methane production from materials equivalent to raw brown algae, without dilution of salinity and without nutrient supply, under 3 consecutive conditions of varying organic loading rates (OLRs) and hydraulic retention time (HRT). Methane production was stable at 2.0gVS/kg/day (39-day HRT); however, it became unstable at 2.9gVS/kg/day (28-day HRT) due to acetate and propionate accumulation. OLR subsequently decreased to 1.7gVS/kg/day (46-day HRT), stabilizing methane production beyond steady state. Methane yield was above 300mL/g VS at all OLRs. These results indicated that the acclimated marine sediment culture was able to produce methane semi-continuously from raw brown algae without dilution and nutrient supply under steady state. Microbial community analysis suggested that hydrogenotrophic methanogens predominated among archaea during unstable methane production, implying a partial shift of the methanogenic pathway from acetoclastic methanogenesis to acetate oxidation.
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530, Japan; CREST, JST, Japan.
authors.forename: Toyokazu
authors.initials: T
authors.lastname: Miura
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530, Japan; CREST, JST, Japan.
authors.forename: Akihisa
authors.initials: A
authors.lastname: Kita
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530, Japan; CREST, JST, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Okamura
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530, Japan; CREST, JST, Japan.
authors.forename: Tsunehiro
authors.initials: T
authors.lastname: Aki
authors.affiliation: Division of Energy and Environmental Engineering, Institute of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan; CREST, JST, Japan.
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Matsumura
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530, Japan; CREST, JST, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Tajima
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530, Japan.
authors.forename: Junichi
authors.initials: J
authors.lastname: Kato
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530, Japan; CREST, JST, Japan. Electronic address: nyutaka@hiroshima-u.ac.jp.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Nakashimada
mesh_terms: D000085:Acetates / Q000737:chemistry; D001105:Archaea / Q000378:metabolism*; D057919:Biological Oxygen Demand Analysis; D019605:Euryarchaeota / Q000378:metabolism; D019015:Geologic Sediments; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000096:biosynthesis*; D059013:Microbial Consortia; D009930:Organic Chemicals; D010100:Oxygen / Q000737:chemistry; D000459:Phaeophyceae / Q000378:metabolism; D054712:Salinity; D014867:Water / Q000737:chemistry
chemical_list: D000085:Acetates; D009930:Organic Chemicals; D014867:Water; D008697:Methane; D010100:Oxygen
keywords: Brown algae; Microbial community; Semi-continuous methane production; Undiluted conditions