Salinity gradients shape the nitrifier community composition in Nanliu River Estuary sediments and the ecophysiology of comammox Nitrospira inopinata

Research output: Contribution to journalResearch articleContributedpeer-review


  • Mengyue Zhao - , East China Normal University (Author)
  • Xiufeng Tang - , East China Normal University (Author)
  • Dongyao Sun - , East China Normal University (Author)
  • Lijun Hou - , East China Normal University (Author)
  • Min Liu - , East China Normal University (Author)
  • Qiang Zhao - , East China Normal University (Author)
  • Uli Klümper - , Chair of Limnology (Author)
  • Zhexue Quan - , Fudan University (Author)
  • Ji Dong Gu - , Technion-Israel Institute of Technology (Author)
  • Ping Han - , East China Normal University (Author)


The recent discovery of complete ammonia oxidizers (comammox), which convert ammonia to nitrate in a single organism, revolutionized the conventional understanding that two types of nitrifying microorganisms have to be involved in the nitrification process for more than 100 years. However, how different types of nitrifiers in response to salinity change remains largely unclear. This study not only investigated nitrifier community (including ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), comammox and nitrite-oxidizing Nitrospira) in the Nanliu estuary to find the ecological relationship between salinity and functional communities and also studied the physiology of a typical comammox Nitrospira inopinata in response to a salinity gradient. Based on sequences retrieved with four sets of functional gene primes, comammox Nitrospira was in general, mainly composed of clade A, with a clear separation of clade A1 subgroup in all samples and clade A2 subgroup in low salinity ones. As expected, group I.1b and group I.1a AOA dominated the AOA community in low- and high-salinity samples, respectively. Nitrosomonas-AOB were detected in all samples while Nitrosospira-AOB were mainly found in relatively high-salinity samples. Regarding general Nitrospira, lineages II and IV were the major groups in most of the samples, while lineage I Nitrospira was only detected in low-salinity samples. Furthermore, the comammox pure culture of N. inopinata showed an optimal salinity at 0.5‰ and ceased to grow at 12.8‰ for ammonia oxidation, but remained active for nitrite oxidation. These results show new evidence regarding niche specificity of different nitrifying microorganisms modulated mainly by salinity, and also a clear response by comammox N. inopinata to a wide range of simulated salinity levels.


Original languageEnglish
Article number148768
JournalScience of the total environment
Publication statusPublished - 15 Nov 2021

External IDs

PubMed 34247082



  • AOA, AOB, Comammox, Estuary, Nitrospira, Salinity