title: Enrichment of denitrifying methane-oxidizing microorganisms using up-flow continuous reactors and batch cultures.
abstract: Denitrifying anaerobic methane oxidizing (DAMO) microorganisms were enriched from paddy field soils using continuous-flow and batch cultures fed with nitrate or nitrite as a sole electron acceptor. After several months of cultivation, the continuous-flow cultures using nitrite showed remarkable simultaneous methane oxidation and nitrite reduction and DAMO bacteria belonging to phylum NC10 were enriched. A maximum volumetric nitrite consumption rate of 70.4±3.4 mg-N·L(-1)·day(-1) was achieved with very short hydraulic retention time of 2.1 hour. In the culture, about 68% of total microbial cells were bacteria and no archaeal cells were detected by fluorescence in situ hybridization. In the nitrate-fed continuous-flow cultures, 58% of total microbial cells were bacteria while archaeal cells accounted for 7% of total cell numbers. Phylogenetic analysis of pmoA gene sequence showed that enriched DAMO bacteria in the continuous-flow cultivation had over 98% sequence similarity to DAMO bacteria in the inoculum. In contrast, for batch culture, the enriched pmoA gene sequences had 89-91% sequence similarity to DAMO bacteria in the inoculum. These results indicate that electron acceptor and cultivation method strongly affect the microbial community structures of DAMO consortia.
authors.affiliation: Department of Civil and Environmental Engineering, Nagaoka University of Technology, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Hatamoto
authors.affiliation: Department of Civil and Environmental Engineering, Nagaoka University of Technology, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kimura
authors.affiliation: Department of Civil and Environmental Engineering, Nagaoka University of Technology, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Civil and Environmental Engineering, Nagaoka University of Technology, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Koizumi
authors.affiliation: Department of Civil and Environmental Engineering, Nagaoka University of Technology, Nagaoka, Niigata, 940-2188, Japan; Department of Civil and Environmental Engineering, Tohoku University, Sendai, Miyagi, 980-8579, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Takahashi
authors.affiliation: Department of Construction Systems Engineering, Anan National College of Technology, Anan, Tokushima, 774-0017, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Kawakami
authors.affiliation: Department of Civil Engineering, Nagaoka National College of Technology, Nagaoka, Niigata, 940-8532, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Araki
authors.affiliation: Department of Civil and Environmental Engineering, Nagaoka University of Technology, Nagaoka, Niigata, 940-2188, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamaguchi
mesh_terms: D001105:Archaea / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics; D058440:Denitrification; D008697:Methane / Q000737:chemistry / Q000378:metabolism; D008772:Methylococcaceae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D009573:Nitrites / Q000737:chemistry / Q000378:metabolism; D010802:Phylogeny; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology
chemical_list: D001426:Bacterial Proteins; D009573:Nitrites; D012987:Soil; D008697:Methane