Quantification of denitrifying bacteria in soils by nirK gene targeted real-time PCR.

Abstract Denitrification, the reduction of nitrate to nitrous oxide or dinitrogen, is the major biological mechanism by which fixed nitrogen returns to the atmosphere from soil and water. Microorganisms capable of denitrification are widely distributed in the environment but little is known about their abundance since quantification is performed using fastidious and time-consuming MPN-based approaches. We used real-time PCR to quantify the denitrifying nitrite reductase gene (nirK), a key enzyme of the denitrifying pathway catalyzing the reduction of soluble nitrogen oxide to gaseous form. The real-time PCR assay was linear over 7 orders of magnitude and sensitive down to 102 copies by assa…

Activity, size and structure of the nitrate reducer community in relation to land-use and fertilization regime in Madagascar

Communication orale, résumé; absent

Direct seeding mulch-based cropping increases both the activity and the abundance of denitrifier communities in a tropical soil

International audience; This study evaluated the impact of direct seeding mulch-based cropping (DMC), as an alternative to conventional tilling (CT), on a functional community involved in N cycling and emission of greenhouse gas nitrous oxide (N2O). The study was carried out for annual soybean/rice crop rotation in the Highlands of Madagascar. The differences between the two soil management strategies (direct seeding with mulched crop residues versus tillage without incorporation of crop residues) were studied along a fertilization gradient (no fertilizer, organic fertilizer, organic plus mineral fertilizers). The activity and size of the denitrifier community were determined by denitrifica…

La communauté nitrate-réductrice : modèle d'évaluation de l'impact du type de fertilisant et du mode de travail du sol à Madagascar

Do tropical soil engineer stimulate the bacterial communities link to N2O emission?

National audience

Changement d'usage des terres et fonctionnement microbien : le cas du semis direct sous couverture végétale à Madagascar

National audience

Corrigendum to “Quantification of denitrifying bacteria in soils by nirK gene targeted real-time PCR” [J. Microbiol. Methods 59 (2004) 327–335]

How agricultural practices affect the different bacterial communities involved in the denitrification process: the case of direct seeding in Madagascar

International audience

Impact of fertilization, tillage and direct seeding on nitrate reducers in Madagascar

La faune du sol tropicale, un facteur de régulation des communautés bactériennes liées aux émissions de gaz à effet de serre

Impact of spatial heterogeneity created by the termite building activity (Cubitermes niokoloensis) on the activity and genetic structure of the denitrifying community

Differential Responses of Nitrate Reducer Community Size, Structure, and Activity to Tillage Systems

ABSTRACT The main objective of this study was to determine how the size, structure, and activity of the nitrate reducer community were affected by adoption of a conservative tillage system as an alternative to conventional tillage. The experimental field, established in Madagascar in 1991, consists of plots subjected to conventional tillage or direct-seeding mulch-based cropping systems (DM), both amended with three different fertilization regimes. Comparisons of size, structure, and activity of the nitrate reducer community in samples collected from the top layer in 2005 and 2006 revealed that all characteristics of this functional community were affected by the tillage system, with increa…

Is soil fauna an important driver of the structure and activities of denitrifier communities in tropical soils?

International audience

Shifts in size, genetic structure and activity of the soil denitrifier community by nematode grazing

International audience; Bacterial-feeding nematodes represent an important driver of the soil microbial activity and diversity. This study aimed at characterizing the impact of nematode grazing on a model functional bacterial guild involved in N-cycling, the denitrifiers. Bacterial-feeding nematodes (Cephalobus pseudoparvus) were inoculated into soil microcosms whose indigenous nematofauna had previously been removed. The size, genetic structure and activity of the soil denitrifier community were characterized 15 and 45 days after nematodes inoculation using quantitative PCR of the nirK, nirS and nosZ denitrification genes, fingerprinting of the nirK and nirS genes and denitrification enzym…

Impact of fertilization and direct seeding on activity and abundance of key denitrifier communities in a tropical soil

Affiche, résumé; The aim of this work was to investigate to which extent different practices impacted on the bacterial communities involved in N2O emission.