Evidence for syntrophic acetate oxidation coupled to hydrogenotrophic methanogenesis in the high-temperature petroleum reservoir of Yabase oil field (Japan)

Authors

  • Daisuke Mayumi,

    1. Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8567, Japan.
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  • Hanako Mochimaru,

    1. Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8567, Japan.
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  • Hideyoshi Yoshioka,

    1. Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8567, Japan.
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  • Susumu Sakata,

    Corresponding author
    1. Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8567, Japan.
      E-mail su-sakata@aist.go.jp; Tel. (+81) 29 861 3898; Fax (+81) 29 861 3666.
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  • Haruo Maeda,

    1. INPEX Corporation, 5-3-1 Akasaka, Minato-ku, Tokyo 107-6332, Japan.
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  • Yoshihiro Miyagawa,

    1. INPEX Corporation, 5-3-1 Akasaka, Minato-ku, Tokyo 107-6332, Japan.
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  • Masayuki Ikarashi,

    1. INPEX Corporation, 5-3-1 Akasaka, Minato-ku, Tokyo 107-6332, Japan.
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  • Mio Takeuchi,

    1. Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8567, Japan.
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  • Yoichi Kamagata

    1. Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-higashi, Sapporo 062-8517, Japan.
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E-mail su-sakata@aist.go.jp; Tel. (+81) 29 861 3898; Fax (+81) 29 861 3666.

Summary

The methanogenic communities and pathways in a high-temperature petroleum reservoir were investigated through incubations of the production water and crude oil, combined with radiotracer experiments and molecular biological analyses. The incubations were conducted without any substrate amendment and under high-temperature and pressurized conditions that mimicked the in situ environment (55°C, 5 MPa). Changes in methane and acetate concentrations during the incubations indicated stoichiometric production of methane from acetate. Rates of hydrogenotrophic methanogenesis measured using [14C]-bicarbonate were 42–68 times those of acetoclastic methanogenesis measured using [2-14C]-acetate, implying the dominance of methane production by syntrophic acetate oxidation coupled to hydrogenotrophic methanogenesis in the environment. 16S rRNA gene sequence analyses of the incubated production water showed bacterial communities dominated by the genus Thermacetogenium, known as a thermophilic syntrophic acetate-oxidizing bacterium, and archaeal communities dominated by thermophilic hydrogenotrophic methanogens belonging to the genus Methanothermobacter. Furthermore, group-specific real-time PCR assays revealed that 16S rRNA gene copy numbers of the hydrogenotrophic methanogens affiliated with the order Methanobacteriales were almost identical to those of archaeal 16S rRNA genes. This study demonstrates that syntrophic acetate oxidation is the main methanogenic pathway in a high-temperature petroleum reservoir.

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