Enrichment of denitrifying methane-oxidizing microorganisms using up-flow continuous reactors and batch cultures

Masashi Hatamoto, Masafumi Kimura, Takafumi Sato, Masato Koizumi, Masanobu Takahashi, Shuji Kawakami, Nobuo Araki, Takashi Yamaguchi

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

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.

Original languageEnglish
Article numbere115823
JournalPloS one
Volume9
Issue number12
DOIs
Publication statusPublished - 2014 Dec 29

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General

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