Can differences in microbial abundances help explain enhanced N2O emissions in a permanent grassland under elevated atmospheric CO2?

Abundance of narG, napA, nirK and nosZ genes of denitrifying bacteria in a Norway spruce forest under different N-deposition

Global Soil Biodiversity Atlas

SPE EA Pôle BIOME The Atlas is divided in 8 chapters covering all the aspects of soil biodiversity: - Chapter I: The soil habitat - Chapter II: Diversity of soil organisms - Chapter III: Geographical and temporal distribution - Chapter IV: Ecosystem functions and services - Chapter V: Threats - Chapter VI: Interventions - Chapter VII: Policy, education and outreach - Chapter VIII: Conclusions Soil biodiversity experts from all over the world are involved in the project aiming at the creation of a reference publication not only for soil biodiversity researchers but also policy makers and general public.; International audience; The Global Soil Biodiversity Initiative (GSBI) and the Joint Res…

Abundance of NARG, NIRK and NOSZ genes of denirifying bacteria during primary successions of a glacier foreland

Primary succession changes diversity, abundance and function of soil microorganisms across glacier forelands

Developing and evaluating tools for assessing the impact of low-dose herbicide nicosulfuron on soil microbial diversity and functioning

Today's conventinal agriculture still relies on the general use of pesticides. Even thought this guarantees production capabilities it also causes environmental pollution having impact on non-targeted organisms. Agricultural practices have been recognized by "The European Soil Framework Directive" as a major threat for soil biodiversity. However, without taking into consideration. recent methodological advances in microbiology, pesticide regulation at EU level relying solely on simple C and N mineralization tè-sts•. ln order to cope with this ECOFUN­-MICROBIODIV project .aim to develop and evaluate tools to estimate the impact of herbicide nicosulfuron on the function and population dynamic…

Local response of bacterial densities and enzyme activities to elevated atmospheric CO2 and different N supply in the rhizosphere of Phaseolus vulgaris L.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; Altered flux of labile C from plant roots into soil is thought to influence growth and maintenance of microbial communities under elevated atmospheric CO2 concentrations. We studied the abundance and function of the soil microbial community at two levels of spatial resolution to assess the response of microorganisms in the rhizosphere of the whole root system and of apical root zones of Phaseolus vulgaris L. to elevated CO2 and high or low N supply. At the coarser resolution, microb…

ECOFUN-MICROBIODIV : an FP7 European project to estimate the ecotoxicological impact of low dose pesticide application in agriculture on soil functional microbial diversity

Soil is hosting a tremendous microbial diversity playing a key-role in a number of soil ecosystemic services including nutrient cycling and filtering. ln the European Soil Framework Directive pesticides are clearly marked as one of the major threats for soil biodiversity and functioning. ln orcier to guarantee minimum effects of pesticide application on soil microbes, pesticicleregistration at EU level (Regulation 2006/388) consiclers the toxicity of pesticides ontci non targefsoil microbes by relying on carbon- and nitrcigen-mineralization tests (OECO 216, 217). However tnese tests do not provicle a comprehensive assessment of pesticides onto soil microbes.-ECOFUN-MICROBIODIV was a project…

The influence of climate change on N-cycling microorganisms in soil

International audience

Influence of land-use intensity on the spatial distribution of N-cycling microorganisms in grassland soils

A geostatistical approach using replicated grassland sites (10 m × 10 m) was applied to investigate the influence of grassland management, i.e. unfertilized pastures and fertilized mown meadows representing low and high land-use intensity (LUI), on soil biogeochemical properties and spatial distributions of ammonia-oxidizing and denitrifying microorganisms in soil. Spatial autocorrelations of the different N-cycling communities ranged between 1.4 and 7.6 m for ammonia oxidizers and from 0.3 m for nosZ-type denitrifiers to scales >14 m for nirK-type denitrifiers. The spatial heterogeneity of ammonia oxidizers and nirS-type denitrifiers increased in high LUI, but decreased for biogeochemical …

Regulation of bacterial and fungal MCPA degradation at the soil–litter interface

Abstract Much is known about mechanisms and regulation of phenoxy acid herbicide degradation at the organism level, whereas the effects of environmental factors on the performance of the phenoxy acid degrading communities in soils are much less clear. In a microcosm experiment we investigated the small-scale effect of litter addition on the functioning of the MCPA degrading communities. 14 C labelled MCPA was applied and the functional genes tfdA and tfdAα were quantified to characterise bacterial MCPA degradation. We identify the transport of litter compounds as an important process that probably regulates the activity of the MCPA degrading community at the soil–litter interface. Two possi…

Ecotoxicological impact of low dose herbicide nicosulfuron on soil microbial biodiversity and functioning

Biogeography of microorganisms in grassland

Structure and activity of the nitrate-reducing community in the rhizosphere of Lolium perenne and Trifolium repens under long-term elevated atmospheric pCO2

Rhizosphere soil was sampled in monocultures of Lolium perenne and Trifolium repens in June and October 2002, at two different nitrogen fertilisation levels (14 and 56 g N m−2 year−1) and under two pCO2 atmospheres (360 and 600 ppmv) at the Swiss FACE (Free Air Carbon dioxide Enrichment) site. Directly extracted soil DNA was analysed with restriction fragment length polymorphism (PCR-RFLP) by use of degenerated primers for the narG gene encoding the active site of the membrane-bound nitrate reductase. The corresponding enzyme activity of the nitrate reductase was determined colorimetrically after 24 h of anaerobic incubation. The narG PCR-RFLP fingerprints showed that the structure of the n…

Response of total and nitrate-dissimilating bacteria to reduced N deposition in a spruce forest soil profile

A field-scale manipulation experiment conducted for 16 years in a Norway spruce forest at Solling, Central Germany, was used to follow the long-term response of total soil bacteria, nitrate reducers and denitrifiers under conditions of reduced N deposition. N was experimentally removed from throughfall by a roof construction (‘clean rain plot’). We used substrate-induced respiration (SIR) to characterize the active fraction of soil microbial biomass and potential nitrate reduction to quantify the activity of nitrate reducers. The abundance of total bacteria, nitrate reducers and denitrifiers in different soil layers was analysed by quantitative PCR of 16S rRNA gene, nitrate reduction and de…

Linking N2O concentrations in different soil depths to denitrification genes abundances under the influence of an elevated atmospheric CO2 concentration

Multiple-scale distribution and function of soil microorganisms

Abundance and activity of nitrate reducers in an arable soil are more affected by temporal variation and soil depth than by elevated atmospheric [CO2]

Elevated atmospheric carbon dioxide concentrations ([CO2]) might change the abundance and the function of soil microorganisms in the depth profile of agricultural soils by plant-mediated reactions. The seasonal pattern of abundance and activity of nitrate-reducing bacteria was studied in a Mini-FACE experiment planted with oilseed rape (Brassica napus). Three depths (0–10, 10–20 and 20–30 cm) were sampled. Analyses of the abundances of total (16S rRNA gene) and nitrate-reducing bacteria (narG, napA) revealed strong influences of sampling date and depth, but no [CO2] effects. Abundance and activity of nitrate reducers were higher in the top soil layer and decreased with depth but were not re…

Impact of elevated CO2 on structure and activity of the nitrate-reducing community in grassland ecosystems

Microbial succession of nitrate-reducing bacteria in the rhizosphere of Poa alpina across a glacier foreland in the Central Alps

International audience; Changes in community structure and activity of the dissimilatory nitrate-reducing community were investigated across a glacier foreland in the Central Alps to gain insight into the successional pattern of this functional group and the driving environmental factors. Bulk soil and rhizosphere soil of Poa alpina was sampled in five replicates in August during the flowering stage and in September after the first snowfalls along a gradient from 25 to 129 years after deglaciation and at a reference site outside the glacier foreland (> 2000 years deglaciated). In a laboratory-based assay, nitrate reductase activity was determined colorimetrically after 24 h of anaerobic inc…

Abundance of narG , nirS , nirK , and nosZ Genes of Denitrifying Bacteria during Primary Successions of a Glacier Foreland

ABSTRACT Quantitative PCR of denitrification genes encoding the nitrate, nitrite, and nitrous oxide reductases was used to study denitrifiers across a glacier foreland. Environmental samples collected at different distances from a receding glacier contained amounts of 16S rRNA target molecules ranging from 4.9 × 10 5 to 8.9 × 10 5 copies per nanogram of DNA but smaller amounts of narG , nirK , and nosZ target molecules. Thus, numbers of narG , nirK , nirS , and nosZ copies per nanogram of DNA ranged from 2.1 × 10 3 to 2.6 × 10 4 , 7.4 × 10 2 to 1.4 × 10 3 , 2.5 × 10 2 to 6.4 × 10 3 , and 1.2 × 10 3 to 5.5 × 10 3 , respectively. The densities of 16S rRNA genes per gram of soil increased with…

Functional stability of the nitrate-reducing community in grassland soils towards high nitrate supply

Abstract To study the effects of short-term fluctuation of nitrate concentrations on the nitrate-reducing community, repacked soil cores were amended with 0, 100 and 300 μ g NO 3 - ‐ N g - 1 soil and incubated for 3, 7 and 14 days, respectively. The nitrate reductase activity was determined in a laboratory-based enzyme assay. In parallel, the community structure of nitrate-reducing microorganisms was characterised by RFLP-PCR using the functional gene narG , which encodes the catalytic site of the membrane-bound nitrate reductase. The community structure remained constant over the experimental period indicating that this functional community is characterised by a high resistance towards flu…