title: Characterization of a halotolerant acetoclastic methanogen highly enriched from marine sediment and its application in removal of acetate.
abstract: A marine sediment collected from Hiroshima Bay was cultured in artificial seawater, containing 0.51 M NaCl and 60 mM acetate and was found to exhibit active methane production at 37°C. Following four successive serial dilutions of cultures in medium containing 0.51 M NaCl, 60 mM acetate, and antibiotics, the well-acclimated methanogen was found to exhibit growth over a range of NaCl concentration (between 0 M and 2.06 M). The specific growth rates of the highly enriched methanogen, termed strain HA, in the absence of NaCl and in the presence of 1.54 M NaCl were estimated to be 0.037 h(-1) and 0.027 h(-1), respectively. The pH and temperature for optimum growth were determined to be 7.0-8.8 and 37°C, respectively. Although cells that had morphology similar to Methanosaeta sp. became dominant in the culture, methane production was still detected in the medium containing 0.51 M NaCl and other substrates such as methanol, formate, and methylamine, indicating contamination with other methanogens. The phylogenetic tree based on 16S rRNA gene sequences revealed that the strain HA was closely related to Methanosaeta harundinacea 6Ac and 8Ac(T), with sequence similarity of 98% and 97%, respectively. The continuous removal of acetate with upflow anaerobic filter reactor for industrial use of strain HA determined a methane production rate of 70 mM/d under condition of 0.51 M NaCl and successful methane production even under 1.54 M NaCl.
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan; CREST, JST, 7 Goban-cho, Chiyoda-ku, Tokyo 102-0076, 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, Hiroshima 739-8530, Japan.
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Suehira
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan; CREST, JST, 7 Goban-cho, Chiyoda-ku, Tokyo 102-0076, 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, Hiroshima 739-8530, Japan; CREST, JST, 7 Goban-cho, Chiyoda-ku, Tokyo 102-0076, 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, Hiroshima 739-8530, Japan; CREST, JST, 7 Goban-cho, Chiyoda-ku, Tokyo 102-0076, Japan.
authors.forename: Tsunehiro
authors.initials: T
authors.lastname: Aki
authors.affiliation: Division of Energy and Environmental Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527, Japan; CREST, JST, 7 Goban-cho, Chiyoda-ku, Tokyo 102-0076, 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, Hiroshima 739-8530, Japan; CREST, JST, 7 Goban-cho, Chiyoda-ku, Tokyo 102-0076, 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, Hiroshima 739-8530, Japan.
authors.forename: Naomichi
authors.initials: N
authors.lastname: Nishio
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan; CREST, JST, 7 Goban-cho, Chiyoda-ku, Tokyo 102-0076, Japan. Electronic address: nyutaka@hiroshima-u.ac.jp.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Nakashimada
mesh_terms: D000085:Acetates / Q000302:isolation & purification* / Q000494:pharmacology; D000693:Anaerobiosis; D019149:Bioreactors; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology; D019605:Euryarchaeota / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D005285:Fermentation; D019015:Geologic Sediments / Q000382:microbiology*; D007564:Japan; D008697:Methane / Q000096:biosynthesis / Q000378:metabolism*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000737:chemistry; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature
chemical_list: D000085:Acetates; D003470:Culture Media; D012336:RNA, Ribosomal, 16S; D012965:Sodium Chloride; D008697:Methane
keywords: Acetoclastic methanogen; Continuous culture; Halotolerant; Marine sediment; Methane fermentation; Methanosaeta; Upflow anaerobic filter reactor