Characterization of nitrous oxide reduction by Azospira sp. HJ23 isolated from advanced wastewater treatment sludge

Hyung Joo Park, Ji Hyeon Kwon, Jeonghee Yun, Kyung Suk Cho

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A new nitrous oxide (N2O)-reducing bacterium was isolated from a consortium that was enriched using advanced wastewater treatment sludge as an inoculum and N2O as the sole nitrogen source. The isolated facultative anaerobe was identified as Azospira sp. HJ23. Azospira sp. HJ23 exhibited optimum N2O-reducing activity with a C/N ratio of 62 at pH 6 in the temperature range of 37 °C to 40 °C. The optimum carbon source for N2O reduction was a mixture of glucose and acetate. The maximum rate of N2O reduction by Azospira sp. HJ23 was 4.8 mmol·g-dry cell−1·h−1, and its N2O-reducing activity was higher than other known N2O reducers. Azospira sp. HJ23 possessed several functional genes for denitrification. These included narG (NO3- reductase), nirK (NO2- reductase), norB (NO reductase), and nosZ (N2O reductase) genes. These results suggest that Azospira sp. HJ23 can be applied in the denitrification process to minimalize N2O emission.

Original languageEnglish
Pages (from-to)1459-1467
Number of pages9
JournalJournal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering
Issue number12
StatePublished - 2020

Bibliographical note

Funding Information:
This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (NRF-2016R1A2B4015007).

Publisher Copyright:
© 2020 Taylor & Francis Group, LLC.


  • Azospirasp
  • denitrification
  • functional denitrifying genes
  • greenhouse gas
  • Nitrous oxide


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