論文

査読有り
2016年8月

Nitrogen and Oxygen Isotope Effects of Ammonia Oxidation by Thermophilic Thaumarchaeota from a Geothermal Water Stream

APPLIED AND ENVIRONMENTAL MICROBIOLOGY
  • Manabu Nishizawa
  • ,
  • Sanae Sakai
  • ,
  • Uta Konno
  • ,
  • Nozomi Nakahara
  • ,
  • Yoshihiro Takaki
  • ,
  • Yumi Saito
  • ,
  • Hiroyuki Imachi
  • ,
  • Eiji Tasumi
  • ,
  • Akiko Makabe
  • ,
  • Keisuke Koba
  • ,
  • Ken Takai

82
15
開始ページ
4492
終了ページ
4504
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1128/AEM.00250-16
出版者・発行元
AMER SOC MICROBIOLOGY

Ammonia oxidation regulates the balance of reduced and oxidized nitrogen pools in nature. Although ammonia-oxidizing archaea have been recently recognized to often outnumber ammonia-oxidizing bacteria in various environments, the contribution of ammonia-oxidizing archaea is still uncertain due to difficulties in the in situ quantification of ammonia oxidation activity. Nitrogen and oxygen isotope ratios of nitrite (delta N-15(NO2-) and delta O-18(NO2-), respectively) are geochemical tracers for evaluating the sources and the in situ rate of nitrite turnover determined from the activities of nitrification and denitrification; however, the isotope ratios of nitrite from archaeal ammonia oxidation have been characterized only for a few marine species. We first report the isotope effects of ammonia oxidation at 70 degrees C by thermophilic Thaumarchaeota populations composed almost entirely of "Candidatus Nitrosocaldus." The nitrogen isotope effect of ammonia oxidation varied with ambient pH (25 parts per thousand to 32 parts per thousand) and strongly suggests the oxidation of ammonia, not ammonium. The delta O-18 value of nitrite produced from ammonia oxidation varied with the delta O-18 value of water in the medium but was lower than the isotopic equilibrium value in water. Because experiments have shown that the half-life of abiotic oxygen isotope exchange between nitrite and water is longer than 33 h at 70 degrees C and pH >= 6.6, the rate of ammonia oxidation by thermophilic Thaumarchaeota could be estimated using delta O-18(NO2-) in geothermal environments, where the biological nitrite turnover is likely faster than 33 h. This study extended the range of application of nitrite isotopes as a geochemical clock of the ammonia oxidation activity to high-temperature environments.
IMPORTANCE
Because ammonia oxidation is generally the rate-limiting step in nitrification that regulates the balance of reduced and oxidized nitrogen pools in nature, it is important to understand the biological and environmental factors underlying the regulation of the rate of ammonia oxidation. The discovery of ammonia-oxidizing archaea (AOA) in marine and terrestrial environments has transformed the concept that ammonia oxidation is operated only by bacterial species, suggesting that AOA play a significant role in the global nitrogen cycle. However, the archaeal contribution to ammonia oxidation in the global biosphere is not yet completely understood. This study successfully identified key factors controlling nitrogen and oxygen isotopic ratios of nitrite produced from thermophilic Thaumarchaeota and elucidated the applicability and its limit of nitrite isotopes as a geochemical clock of ammonia oxidation rate in nature. Oxygen isotope analysis in this study also provided new biochemical information on archaeal ammonia oxidation.

Web of Science ® 被引用回数 : 14

リンク情報
DOI
https://doi.org/10.1128/AEM.00250-16
Web of Science
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000379772200004&DestApp=WOS_CPL
URL
http://www.scopus.com/inward/record.url?eid=2-s2.0-84979941641&partnerID=MN8TOARS
URL
http://orcid.org/0000-0001-5426-814X
ID情報
  • DOI : 10.1128/AEM.00250-16
  • ISSN : 0099-2240
  • eISSN : 1098-5336
  • ORCIDのPut Code : 49208415
  • SCOPUS ID : 84979941641
  • Web of Science ID : WOS:000379772200004

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