5 years ago

Kinetics of NH3-oxidation, NO-turnover, N2O-production and electron flow during oxygen depletion in model bacterial and archaeal ammonia oxidisers

Graeme W. Nicol, Pawel Lycus, James I. Prosser, Lars R. Bakken, Åsa Frostegård, Cécile Gubry-Rangin, Linda Hink
Ammonia oxidising bacteria (AOB) are thought to emit more nitrous oxide (N2O) than ammonia oxidising archaea (AOA), due to their higher N2O yield under oxic conditions and denitrification in response to oxygen (O2) limitation. We determined the kinetics of growth and turnover of nitric oxide (NO) and N2O at low cell densities of Nitrosomonas europaea (AOB) and Nitrosopumilus maritimus (AOA) during gradual depletion of TAN (NH3 + NH4+) and O2. Half-saturation constants for O2 and TAN were similar to those determined by others, except for the half-saturation constant for ammonium in N. maritimus (0.2 mM), which is orders of magnitudes higher than previously reported. For both strains, cell-specific rates of NO turnover and N2O production reached maxima near O2 half-saturation constant concentration (2-10 µM O2) and decreased to zero in response to complete O2-depletion. Modelling of the electron flow in N. europaea demonstrated low electron flow to denitrification (≤1.2% of the total electron flow), even at sub-micromolar O2 concentrations. The results corroborate current understanding of the role of NO in the metabolism of AOA and suggest that denitrification is inconsequential for the energy metabolism of AOB, but possibly important as a route for dissipation of electrons at high ammonium concentration. This article is protected by copyright. All rights reserved.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1111/1462-2920.13914

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.