Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 13, issue 7
Biogeosciences, 13, 2051–2060, 2016
https://doi.org/10.5194/bg-13-2051-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 13, 2051–2060, 2016
https://doi.org/10.5194/bg-13-2051-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 07 Apr 2016

Research article | 07 Apr 2016

Nitrification of archaeal ammonia oxidizers in a high- temperature hot spring

Shun Chen, Xiaotong Peng, Hengchao Xu, and Kaiwen Ta Shun Chen et al.
  • Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China

Abstract. The oxidation of ammonia by microbes has been shown to occur in diverse natural environments. However, the link of in situ nitrification activity to taxonomic identities of ammonia oxidizers in high-temperature environments remains poorly understood. Here, we studied in situ ammonia oxidation rates and the diversity of ammonia-oxidizing Archaea (AOA) in surface and bottom sediments at 77 °C in the Gongxiaoshe hot spring, Tengchong, Yunnan, China. The in situ ammonia oxidation rates measured by the 15N-NO3 pool dilution technique in the surface and bottom sediments were 4.80 and 5.30 nmol N g−1 h−1, respectively. Real-time quantitative polymerase chain reaction (qPCR) indicated that the archaeal 16S rRNA genes and amoA genes were present in the range of 0.128 to 1.96  ×  108 and 2.75 to 9.80  ×  105 gene copies g−1 sediment, respectively, while bacterial amoA was not detected. Phylogenetic analysis of 16S rRNA genes showed high sequence similarity to thermophilic Candidatus Nitrosocaldus yellowstonii, which represented the most abundant operational taxonomic units (OTU) in both surface and bottom sediments. The archaeal predominance was further supported by fluorescence in situ hybridization (FISH) visualization. The cell-specific rate of ammonia oxidation was estimated to range from 0.410 to 0.790 fmol N archaeal cell−1 h−1, higher than those in the two US Great Basin hot springs. These results suggest the importance of archaeal rather than bacterial ammonia oxidation in driving the nitrogen cycle in terrestrial geothermal environments.

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The oxidation of ammonia by microbes has been shown to occur in diverse natural environments. However, the link of in situ nitrification activity to taxonomic identities of ammonia oxidizers in high-temperature environments remains poorly understood. Here, in combination of culture-independent and culture-dependent approaches, we provide direct evidences that ammonia-oxidizing Archaea (AOA) are indeed responsible for the major portion of ammonia oxidation in high-temperature hot springs.
The oxidation of ammonia by microbes has been shown to occur in diverse natural environments....
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