Community-specific pH response of denitrification: experiments with cells extracted from organic soils
Open Access
- 13 December 2011
- journal article
- research article
- Published by Oxford University Press (OUP) in FEMS Microbiology Ecology
- Vol. 79 (2), 530-541
- https://doi.org/10.1111/j.1574-6941.2011.01233.x
Abstract
Denitrifying prokaryotes are phylogenetically and functionally diverse. Little is known about the relationship between soil denitrifier community composition and functional traits. We extracted bacterial cells from three cultivated peat soils with contrasting native pH by density gradient centrifugation and investigated their kinetics of oxygen depletion and , NO, N2O and N2 accumulation during initially hypoxic batch incubations (0.5–1 μM O2) in minimal medium buffered at either pH 5.4 or 7.1 (2 mM glutamate, 2 mM ). The three communities differed strikingly in accumulation and transient N2O accumulation at the two pH levels, whereas NO peak concentrations (24–53 nM) were similar across all communities and pH treatments. The results confirm that the communities represent different denitrification regulatory phenotypes, as indicated by previous denitrification bioassays with nonbuffered slurries of the same three soils. The composition of the extracted cells resembled that of the parent soils (PCR-TRFLP analyses of 16S rRNA genes,nirK,nirS and nosZ), which were found to differ profoundly in their genetic composition (Braker et al., 2012). Together, this suggests that direct pH response of denitrification depends on denitrifier community composition, with implications for the propensity of soils to emit N2O to the atmosphere.Keywords
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