N2O and NOy production by the comammox bacterium Nitrospira inopinata in comparison with canonical ammonia oxidizers

Research output: Contribution to journalResearch articleContributedpeer-review


  • Ping Han - , East China Normal University (Author)
  • Dianming Wu - , East China Normal University (Author)
  • Dongyao Sun - , East China Normal University (Author)
  • Mengyue Zhao - , East China Normal University (Author)
  • Mengdi Wang - , East China Normal University (Author)
  • Teng Wen - , Nanjing Normal University (Author)
  • Jinbo Zhang - , Nanjing Normal University (Author)
  • Lijun Hou - , East China Normal University (Author)
  • Min Liu - , East China Normal University (Author)
  • Uli Klümper - , Institute of Hydrobiology (Author)
  • Yanling Zheng - , East China Normal University (Author)
  • Hong Po Dong - , East China Normal University (Author)
  • Xia Liang - , East China Normal University (Author)
  • Guoyu Yin - , East China Normal University (Author)


Nitrous oxide (N2O) and NOy (nitrous acid (HONO) + nitric oxide (NO) + nitrogen dioxide (NO2)) are released as byproducts or obligate intermediates during aerobic ammonia oxidation, and further influence global warming and atmospheric chemistry. The ammonia oxidation process is catalyzed by groups of globally distributed ammonia-oxidizing microorganisms, which are playing a major role in atmospheric N2O and NOy emissions. Yet, little is known about HONO and NO2 production by the recently discovered, widely distributed complete ammonia oxidizers (comammox), able to individually perform the oxidation of ammonia to nitrate via nitrite. Here, we examined the N2O and NOy production patterns by comammox bacterium Nitrospira inopinata during aerobic ammonia oxidation, in comparison to its canonical ammonia-converting counterparts, representatives of the ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). Our findings, i) show low yield NOy production by the comammox bacterium compared to AOB; ii) highlight the role of the NO reductase in the biological formation of N2O based on results from NH2OH inhibition assays and its stimulation during archaeal and bacterial ammonia oxidations; iii) postulate that the lack of hydroxylamine (NH2OH) and NO transformation enzymatic activities may lead to a buildup of NH2OH/NO which can abiotically react to N2O; iv) collectively confirm restrained N2O and NOy emission by comammox bacteria, an unneglectable consortium of microbes in global atmospheric emission of reactive nitrogen gases.


Original languageEnglish
Article number116728
JournalWater research
Publication statusPublished - 15 Feb 2021

External IDs

PubMed 33326897
ORCID /0000-0002-4169-6548/work/142247354



  • Ammonia oxidation, Comammox Nitrospira, HONO, NO, Nitric oxide reductase

Library keywords