Dissimilatory Nitrate Reduction to Ammonium and Responsible Microbes in Japanese Rice Paddy Soil

• Nojiri Yosuke

  Graduate School of Agricultural and Life Sciences, The University of Tokyo

• Kaneko Yuka

  Graduate School of Agricultural and Life Sciences, The University of Tokyo

• Azegami Yoichi

  Graduate School of Agricultural and Life Sciences, The University of Tokyo

• Shiratori Yutaka

  Niigata Agricultural Research Institute

• Ohte Nobuhito

  Graduate School of Informatics, Kyoto University

• Senoo Keishi

  Graduate School of Agricultural and Life Sciences, The University of Tokyo Collaborative Research Institute for Innovative Microbiology, The University of Tokyo

• Otsuka Shigeto

  Graduate School of Agricultural and Life Sciences, The University of Tokyo Collaborative Research Institute for Innovative Microbiology, The University of Tokyo

• Isobe Kazuo

  Graduate School of Agricultural and Life Sciences, The University of Tokyo

Abstract

Nitrification–denitrification processes in the nitrogen cycle have been extensively examined in rice paddy soils. Nitrate is generally depleted in the reduced soil layer below the thin oxidized layer at the surface, and this may be attributed to high denitrification activity. In the present study, we investigated dissimilatory nitrate reduction to ammonium (DNRA), which competes with denitrification for nitrate, in order to challenge the conventional view of nitrogen cycling in paddy soils. We performed paddy soil microcosm experiments using ¹⁵N tracer analyses to assess DNRA and denitrification rates and conducted clone library analyses of transcripts of nitrite reductase genes (nrfA, nirS, and nirK) in order to identify the microbial populations carrying out these processes. The results obtained showed that DNRA occurred to a similar extent to denitrification and appeared to be enhanced by a nitrate limitation relative to organic carbon. We also demonstrated that different microbial taxa were responsible for these distinct processes. Based on these results and previous field observations, nitrate produced by nitrification within the surface oxidized layer may be reduced not only to gaseous N₂ via denitrification, but also to NH₄⁺ via DNRA, within the reduced layer. The present results also indicate that DNRA reduces N loss through denitrification and nitrate leaching and provides ammonium to rice roots in rice paddy fields.

Journal

• Microbes and Environments

  Microbes and Environments 35 (4), n/a-, 2020

  Japanese Society of Microbial Ecology / Japanese Society of Soil Microbiology / Taiwan Society of Microbial Ecology / Japanese Society of Plant Microbe Interactions / Japanese Society for Extremophiles

Keywords

• DNRA
• denitrification
• <i>nrfA</i>
• <i>nirK</i>
• <i>nirS</i>

Details

• CRID: 1390848647562056960
• NII Article ID: 130007923243
• NII Book ID: AA11551577
• DOI: 10.1264/jsme2.me20069
• ISSN: 13474405
• ISSN: 13426311
• NDL BIB ID: 031205579
• PubMed: 33028782
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I031205579
• Web Site: https://www.jstage.jst.go.jp/article/jsme2/35/4/35_ME20069/_pdf
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • PubMed
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed