Nitrous oxide production and methane oxidation by different ammonia-oxidizing bacteria
1Department of Biotechnological Sciences, Agricultural University of Norway, 1432 Aas, Norway.
Applied and Environmental Microbiology
|May 29, 1999
Summary
Ammonia-oxidizing bacteria (AOB) produce nitrous oxide (N2O) consistently, unlike related species that increase N2O under stress. Tested AOB strains do not significantly oxidize atmospheric methane.
Area of Science:
- Environmental Microbiology
- Soil Science
- Biogeochemistry
Background:
- Ammonia-oxidizing bacteria (AOB) are crucial in nitrogen cycling and greenhouse gas production.
- Nitrosomonas europaea is often studied, but Nitrosospira spp. are more prevalent in soils.
- Understanding N2O production and methane oxidation by AOB is vital for soil ecosystem management.
Purpose of the Study:
- To compare aerobic N2O production in various soil-isolated Nitrosospira strains and type strains.
- To investigate the influence of substrate supply, pH, and nutrient limitation on N2O release.
- To assess the contribution of these AOB to atmospheric methane oxidation.
Main Methods:
- Isolation and phylogenetic characterization of six Nitrosospira strains from soil.
- Cultivation of AOB strains under controlled aerobic conditions with varying substrates (urea, ammonium) and pH.
- Quantification of N2O production via gas chromatography and measurement of methane oxidation rates.
Main Results:
- All tested Nitrosospira strains exhibited a consistent aerobic N2O production rate (0.07–0.1%) regardless of substrate or pH.
- Nitrosomonas europaea and Nitrosospira multiformis showed increased N2O release (1–5%) under substrate limitation or low pH.
- Phosphate buffer significantly enhanced N2O release across all AOB strains; no significant methane oxidation was detected.
Conclusions:
- Nitrosospira strains contribute consistently to soil N2O emissions, while N. europaea and N. multiformis are more sensitive to environmental conditions.
- Environmental factors like pH and substrate availability strongly influence N2O production in certain AOB.
- The tested AOB strains play a negligible role in the oxidation of atmospheric methane in soils.
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