Microbial nitrification in throughfall of a Japanese cedar associated with archaea from the tree canopy

Keiji Watanabe, Ayato Kohzu, Wataru Suda, Shigeki Yamamura, Takejiro Takamatsu, Akio Takenaka, Masami Kanao Koshikawa, Seiji Hayashi, Mirai Watanabe

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)


To investigate the nitrification potential of phyllospheric microbes, we incubated throughfall samples collected under the canopies of Japanese cedar (Cryptomeria japonica) and analyzed the transformation of inorganic nitrogen in the samples. Nitrate concentration increased in the unfiltered throughfall after 4 weeks of incubation, but remained nearly constant in the filtered samples (pore size: 0.2 and 0.4 µm). In the unfiltered samples, δ18O and δ15N values of nitrate decreased during incubation. In addition, archaeal ammonia monooxygenase subunit A (amoA) genes, which participate in the oxidation of ammonia, were found in the throughfall samples, although betaproteobacterial amoA genes were not detected. The amoA genes recovered from the leaf surface of C. japonica were also from archaea. Conversely, nitrate production, decreased isotope ratios of nitrate, and the presence of amoA genes was not observed in rainfall samples collected from an open area. Thus, the microbial nitrification that occurred in the incubated throughfall is likely due to ammonia-oxidizing archaea that were washed off the tree canopy by precipitation.

Original languageEnglish
Article number1596
Issue number1
Publication statusPublished - 2016 Dec 1


  • Ammonia-oxidizing archaea
  • Nitrification
  • Phyllosphere
  • Throughfall
  • amoA

ASJC Scopus subject areas

  • General


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