Details
| Original language | English |
|---|---|
| Pages (from-to) | 4882-4896 |
| Number of pages | 15 |
| Journal | Environmental microbiology |
| Volume | 19 |
| Issue number | 12 |
| Publication status | Published - Dec 2017 |
| Externally published | Yes |
Abstract
Ammonia oxidising bacteria (AOB) are thought to emit more nitrous oxide (N2 O) than ammonia oxidising archaea (AOA), due to their higher N2 O 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 N2 O 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 N2 O 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.
Keywords
- Ammonia/metabolism, Ammonium Compounds/metabolism, Archaea/metabolism, Denitrification/physiology, Electrons, Kinetics, Nitric Oxide/biosynthesis, Nitrosomonas europaea/metabolism, Nitrous Oxide/metabolism, Oxidation-Reduction, Oxygen/metabolism
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)
- Ecology, Evolution, Behavior and Systematics
- Immunology and Microbiology(all)
- Microbiology
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In: Environmental microbiology, Vol. 19, No. 12, 12.2017, p. 4882-4896.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Kinetics of NH3 -oxidation, NO-turnover, N2 O-production and electron flow during oxygen depletion in model bacterial and archaeal ammonia oxidisers
AU - Hink, Linda
AU - Lycus, Pawel
AU - Gubry-Rangin, Cécile
AU - Frostegård, Åsa
AU - Nicol, Graeme W
AU - Prosser, James I
AU - Bakken, Lars R
N1 - Funding information: The authors are members of the Nitrous Oxide Research Alliance (NORA), a Marie Sk?odowska-Curie ITN and research project under the EU’s seventh framework program (FP7), 316472. GN is funded by the AXA Research Fund and CGR by a Royal Society fellowship. We thank Lars Molstad and Peter Do€rsch for their generous and invaluable technical assistance. We thank Martin G Klotz for a very constructive review of our paper, and especially for pointing out the possible electron dissipation via periplasmic cytochromes, thus providing a possible explanation for the high N2O at high ammonium concentrations.
PY - 2017/12
Y1 - 2017/12
N2 - Ammonia oxidising bacteria (AOB) are thought to emit more nitrous oxide (N2 O) than ammonia oxidising archaea (AOA), due to their higher N2 O 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 N2 O 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 N2 O 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.
AB - Ammonia oxidising bacteria (AOB) are thought to emit more nitrous oxide (N2 O) than ammonia oxidising archaea (AOA), due to their higher N2 O 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 N2 O 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 N2 O 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.
KW - Ammonia/metabolism
KW - Ammonium Compounds/metabolism
KW - Archaea/metabolism
KW - Denitrification/physiology
KW - Electrons
KW - Kinetics
KW - Nitric Oxide/biosynthesis
KW - Nitrosomonas europaea/metabolism
KW - Nitrous Oxide/metabolism
KW - Oxidation-Reduction
KW - Oxygen/metabolism
UR - http://www.scopus.com/inward/record.url?scp=85030097868&partnerID=8YFLogxK
U2 - 10.1111/1462-2920.13914
DO - 10.1111/1462-2920.13914
M3 - Article
C2 - 28892283
VL - 19
SP - 4882
EP - 4896
JO - Environmental microbiology
JF - Environmental microbiology
SN - 1462-2912
IS - 12
ER -