A mixture of nitrite-oxidizing and denitrifying microorganisms affects the δ18O of dissolved nitrate during anaerobic microbial denitrification depending on the δ18O of ambient water

Wunderlich, Anja; Meckenstock, Rainer U.; Einsiedl, Florian

doi:10.1016/j.gca.2013.05.028

Cited by 49 publications

(24 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The remaining nitrate pool becomes 15 N-and 18 O-enriched because the lighter isotopomers are enzymatically favored by denitrifiers (Pérez et al 2006;Wunderlich et al 2013). In the Gigante Fertilization Experiment, positive correlations between d 15 N and d 18 O values of soil nitrate following N addition provide evidence for the imprint of gaseous losses on soil nitrate ( Supplementary Fig.…”

Section: Discussionmentioning

confidence: 99%

Stable nitrogen isotope patterns of trees and soils altered by long-term nitrogen and phosphorus addition to a lowland tropical rainforest

et al. 2014

View full text Add to dashboard Cite

Foliar nitrogen (N) isotope ratios (d 15 N) are used as a proxy for N-cycling processes, including the ''openness'' of the N cycle and the use of distinct N sources, but there is little experimental support for such proxies in lowland tropical forest. To address this, we examined the d 15 N values of soluble soil N and canopy foliage of four tree species after 13 years of factorial N and P addition to a mature lowland rainforest. We hypothesized that N addition would lead to 15 Nenriched soil N forms due to fractionating losses, whereas P addition would reduce N losses as the plants and microbes adjusted their stoichiometric demands. Chronic N addition increased the concentration and d 15 N value of soil nitrate and d 15 N in live and senesced leaves in two of four tree species, but did not affect ammonium or dissolved organic N. Phosphorus addition significantly increased foliar d 15 N in one tree species and elicited significant N 9 P interactions in two others due to a reduction in foliar d 15 N enrichment under N and P co-addition. Isotope mixing models indicated that three of four tree species increased their use of nitrate relative to ammonium following N addition, supporting the expectation that tropical trees use the most available form of mineral N. Previous observations that anthropogenic N deposition in this tropical region have led to increasing foliar d 15 N values over decadal time-scales is now mechanistically linked to greater usage of 15 N-enriched nitrate.

show abstract

Section: Discussionmentioning

confidence: 99%

Stable nitrogen isotope patterns of trees and soils altered by long-term nitrogen and phosphorus addition to a lowland tropical rainforest

et al. 2014

View full text Add to dashboard Cite

show abstract

“…N trajectories between cultures and freshwater environments (39,40), although this tenet has not been examined specifically. The potential for analogous biogeochemical dynamics to affect isotope distributions in freshwater and marine systems clearly merits exploring.…”

mentioning

confidence: 99%

Isotopic overprinting of nitrification on denitrification as a ubiquitous and unifying feature of environmental nitrogen cycling

Granger

Wankel

2016

Proc. Natl. Acad. Sci. U.S.A.

191

212

View full text Add to dashboard Cite

show abstract

“…Workers who have acknowledge this discrepancy invoke fundamental differences in fractionation between marine and freshwater denitrifying systems, including mutability of the Nar ‐mediated Δδ 18 O:Δδ 15 N trajectory (Knöller et al ), or a substantial contribution of the auxiliary Nap

{NO}_{3}^{-}

reductase to bulk

{NO}_{3}^{-}

reduction in freshwater systems (Frey et al ; Wenk et al ). Alternatively, the divergence in Δδ 18 O:Δδ 15 N coupling in freshwater systems compared to culture observations may portend of biological

{NO}_{3}^{-}

production by nitrification and/or anammox imprinted on the isotopic signal of denitrification (Wunderlich et al ; Wenk et al ; Granger and Wankel in unpubl. ).…”

mentioning

confidence: 99%

Enzyme level N and O isotope effects of assimilatory and dissimilatory nitrate reduction

Treibergs

Granger

2016

Limnology & Oceanography

View full text Add to dashboard Cite

To provide mechanistic constraints to interpret nitrogen (N) and oxygen (O) isotope ratios of nitrate ( NO3−), 15N/14N and 18O/16O, in the environment, we measured the enzymatic NO3− N and O isotope effects (15ε and 18ε) during its reduction by NO3− reductase enzymes, including (1) a prokaryotic respiratory NO3− reductase, Nar, from the heterotrophic denitrifier Paracoccus denitrificans, (2) eukaryotic assimilatory NO3− reductases, eukNR, from Pichia angusta and from Arabidopsis thaliana, and (3) a prokaryotic periplasmic NO3− reductase, Nap, from the photoheterotroph Rhodobacter sphaeroides. Enzymatic Nar and eukNR assays with artificial viologen electron donors yielded identical 18ε and 15ε of ∼28‰, regardless of [ NO3−] or assay temperature, suggesting analogous kinetic mechanisms with viologen reductants. Nar assays fuelled with the physiological reductant hydroquinone (HQ) also yielded 18ε ≈ 15ε, but variable amplitudes from 21‰ to 33.0‰ in association with [ NO3−], suggesting analogous substrate sensitivity in vivo. Nap assays fuelled by viologen revealed 18ε:15ε of 0.50, where 18ε ≈ 19‰ and 15ε ≈ 38‰, indicating a distinct catalytic mechanism than Nar and eukNR. Nap isotope effects measured in vivo showed a similar 18ε:15ε of 0.57, but reduced 18ε ≈ 11‰ and 15ε ≈ 19‰. Together, the results confirm identical enzymatic 18ε and 15ε during NO3− assimilation and denitrification, reinforcing the reliability of this benchmark to identify NO3− consumption in the environment. However, the amplitude of enzymatic isotope effects is apt to vary in vivo. The distinctive signature of Nap is of interest for deciphering catalytic mechanisms but may be negligible in most environments given its physiological role.

show abstract

A mixture of nitrite-oxidizing and denitrifying microorganisms affects the δ18O of dissolved nitrate during anaerobic microbial denitrification depending on the δ18O of ambient water

Cited by 49 publications

References 65 publications

Stable nitrogen isotope patterns of trees and soils altered by long-term nitrogen and phosphorus addition to a lowland tropical rainforest

Stable nitrogen isotope patterns of trees and soils altered by long-term nitrogen and phosphorus addition to a lowland tropical rainforest

Isotopic overprinting of nitrification on denitrification as a ubiquitous and unifying feature of environmental nitrogen cycling

Enzyme level N and O isotope effects of assimilatory and dissimilatory nitrate reduction

Contact Info

Product

Resources

About