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The diversity of the N2O reducers matters for the N2O:N2 denitrification end-product ratio across an annual and a perennial cropping system.

Domeignoz-Horta LA, Spor A, Bru D, Breuil MC, Bizouard F, Léonard J, Philippot L - Front Microbiol (2015)

Bottom Line: The abundance of N2O-reducers and producers was quantified by real-time PCR, and the diversity of both nosZ clades was determined by 454 pyrosequencing.Overall, the results showed limited differences between management practices but there were significant differences between cropping systems in both the abundance and structure of the nosZII community, as well as in the [rN2O/r(N2O+N2)] ratio.Potential denitrification activity and potential N2O production were explained mainly by the soil properties while the diversity of the nosZII clade on its own explained 26% of the denitrification end-product ratio, which highlights the importance of understanding the ecology of this newly identified clade of N2O reducers for mitigation strategies.

View Article: PubMed Central - PubMed

Affiliation: INRA, UMR 1347 Agroécologie Dijon, France.

ABSTRACT
Agriculture is the main source of terrestrial emissions of N2O, a potent greenhouse gas and the main cause of ozone layer depletion. The reduction of N2O into N2 by microorganisms carrying the nitrous oxide reductase gene (nosZ) is the only biological process known to eliminate this greenhouse gas. Recent studies showed that a previously unknown clade of N2O-reducers was related to the capacity of the soil to act as an N2O sink, opening the way for new strategies to mitigate emissions. Here, we investigated whether the agricultural practices could differently influence the two N2O reducer clades with consequences for denitrification end-products. The abundance of N2O-reducers and producers was quantified by real-time PCR, and the diversity of both nosZ clades was determined by 454 pyrosequencing. Potential N2O production and potential denitrification activity were used to calculate the denitrification gaseous end-product ratio. Overall, the results showed limited differences between management practices but there were significant differences between cropping systems in both the abundance and structure of the nosZII community, as well as in the [rN2O/r(N2O+N2)] ratio. More limited differences were observed in the nosZI community, suggesting that the newly identified nosZII clade is more sensitive than nosZI to environmental changes. Potential denitrification activity and potential N2O production were explained mainly by the soil properties while the diversity of the nosZII clade on its own explained 26% of the denitrification end-product ratio, which highlights the importance of understanding the ecology of this newly identified clade of N2O reducers for mitigation strategies.

No MeSH data available.


Related in: MedlinePlus

Potential N2O emissions (A), potential denitrification activity (B) and denitrification gaseous end-product ratio [rN2O/r(N2O+N2)] (C). Means ± sem per treatments within each experimental block are given. BE and ORE represent the respective cropping systems. Significant differences between treatments are indicated with different letters (anova followed by Tukey HSD test, P < 0.05).
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Figure 1: Potential N2O emissions (A), potential denitrification activity (B) and denitrification gaseous end-product ratio [rN2O/r(N2O+N2)] (C). Means ± sem per treatments within each experimental block are given. BE and ORE represent the respective cropping systems. Significant differences between treatments are indicated with different letters (anova followed by Tukey HSD test, P < 0.05).

Mentions: To assess the activity of the N2O reducing microbial communities, the potential N2O production and potential denitrification activity (PDA) were quantified and used to calculate the denitrification end-product ratio [rN2O/r(N2O+N2)]. The potential activity of denitrifying microorganisms varied in all cropping systems, ranging from 0.03 (CI95% = [0− 0.09]) to 0.85 (CI95% = [0.79−0.91]) and 0.17 (CI95% = [0.07−0.27]) to 1.51 (CI95% = [1.41−1.61]) μg N2O-N g−1 soil DW h−1 for potential N2O and PDA, respectively (Figures 1A,B). The [rN2O/r(N2O+N2)] ratio ranged between 0.18 (CI95% = [0.08–0.28]) and 1 (CI95% = [0.9–1.1]) (Figure 1C) and was significantly higher (P < 0.001) for BE than for ORE cropping system with an average of 0.65 (CI95% = 0.81–0.48) and 0.29 (CI95% = 0.24–0.34), respectively. There were significant differences in [rN2O/r(N2O+N2)] between the early (ME) and late harvest (ML) practices for plots planted with Miscanthus giganteus (P < 0.05) (Figure 1B) with the denitrification end product being mainly N2O in the early harvested plots with a [rN2O/r(N2O+N2)] close to 1 (Figure 1C). For switchgrass, there was the same tendency to have a higher [rN2O/r(N2O+N2)] with the early harvest practice, although this was not significant.


The diversity of the N2O reducers matters for the N2O:N2 denitrification end-product ratio across an annual and a perennial cropping system.

Domeignoz-Horta LA, Spor A, Bru D, Breuil MC, Bizouard F, Léonard J, Philippot L - Front Microbiol (2015)

Potential N2O emissions (A), potential denitrification activity (B) and denitrification gaseous end-product ratio [rN2O/r(N2O+N2)] (C). Means ± sem per treatments within each experimental block are given. BE and ORE represent the respective cropping systems. Significant differences between treatments are indicated with different letters (anova followed by Tukey HSD test, P < 0.05).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585238&req=5

Figure 1: Potential N2O emissions (A), potential denitrification activity (B) and denitrification gaseous end-product ratio [rN2O/r(N2O+N2)] (C). Means ± sem per treatments within each experimental block are given. BE and ORE represent the respective cropping systems. Significant differences between treatments are indicated with different letters (anova followed by Tukey HSD test, P < 0.05).
Mentions: To assess the activity of the N2O reducing microbial communities, the potential N2O production and potential denitrification activity (PDA) were quantified and used to calculate the denitrification end-product ratio [rN2O/r(N2O+N2)]. The potential activity of denitrifying microorganisms varied in all cropping systems, ranging from 0.03 (CI95% = [0− 0.09]) to 0.85 (CI95% = [0.79−0.91]) and 0.17 (CI95% = [0.07−0.27]) to 1.51 (CI95% = [1.41−1.61]) μg N2O-N g−1 soil DW h−1 for potential N2O and PDA, respectively (Figures 1A,B). The [rN2O/r(N2O+N2)] ratio ranged between 0.18 (CI95% = [0.08–0.28]) and 1 (CI95% = [0.9–1.1]) (Figure 1C) and was significantly higher (P < 0.001) for BE than for ORE cropping system with an average of 0.65 (CI95% = 0.81–0.48) and 0.29 (CI95% = 0.24–0.34), respectively. There were significant differences in [rN2O/r(N2O+N2)] between the early (ME) and late harvest (ML) practices for plots planted with Miscanthus giganteus (P < 0.05) (Figure 1B) with the denitrification end product being mainly N2O in the early harvested plots with a [rN2O/r(N2O+N2)] close to 1 (Figure 1C). For switchgrass, there was the same tendency to have a higher [rN2O/r(N2O+N2)] with the early harvest practice, although this was not significant.

Bottom Line: The abundance of N2O-reducers and producers was quantified by real-time PCR, and the diversity of both nosZ clades was determined by 454 pyrosequencing.Overall, the results showed limited differences between management practices but there were significant differences between cropping systems in both the abundance and structure of the nosZII community, as well as in the [rN2O/r(N2O+N2)] ratio.Potential denitrification activity and potential N2O production were explained mainly by the soil properties while the diversity of the nosZII clade on its own explained 26% of the denitrification end-product ratio, which highlights the importance of understanding the ecology of this newly identified clade of N2O reducers for mitigation strategies.

View Article: PubMed Central - PubMed

Affiliation: INRA, UMR 1347 Agroécologie Dijon, France.

ABSTRACT
Agriculture is the main source of terrestrial emissions of N2O, a potent greenhouse gas and the main cause of ozone layer depletion. The reduction of N2O into N2 by microorganisms carrying the nitrous oxide reductase gene (nosZ) is the only biological process known to eliminate this greenhouse gas. Recent studies showed that a previously unknown clade of N2O-reducers was related to the capacity of the soil to act as an N2O sink, opening the way for new strategies to mitigate emissions. Here, we investigated whether the agricultural practices could differently influence the two N2O reducer clades with consequences for denitrification end-products. The abundance of N2O-reducers and producers was quantified by real-time PCR, and the diversity of both nosZ clades was determined by 454 pyrosequencing. Potential N2O production and potential denitrification activity were used to calculate the denitrification gaseous end-product ratio. Overall, the results showed limited differences between management practices but there were significant differences between cropping systems in both the abundance and structure of the nosZII community, as well as in the [rN2O/r(N2O+N2)] ratio. More limited differences were observed in the nosZI community, suggesting that the newly identified nosZII clade is more sensitive than nosZI to environmental changes. Potential denitrification activity and potential N2O production were explained mainly by the soil properties while the diversity of the nosZII clade on its own explained 26% of the denitrification end-product ratio, which highlights the importance of understanding the ecology of this newly identified clade of N2O reducers for mitigation strategies.

No MeSH data available.


Related in: MedlinePlus