0000000000737632
AUTHOR
Franck Poly
Influence of plant traits, soil microbial properties, and abiotic parameters on nitrogen turnover of grassland ecosystems
International audience; Although it is known that multiple interactions among plant functional traits, microbial properties , and abiotic soil parameters influence the nutrient turnover, the relative contribution of each of these groups of variables is poorly understood. We manipulated grassland plant functional composition and soil nitrogen (N) availability in a multisite mesocosm experiment to quantify their relative effects on soil N turnover. Overall, root traits, arbuscular mycorrhizal colonization, denitrification potential, as well as N availability and water availability, best explained the variation in measured ecosystem properties, especially the trade-off between nutrient sequest…
Characterization of Bacterial and Fungal Soil Communities by Automated Ribosomal Intergenic Spacer Analysis Fingerprints: Biological and Methodological Variability
ABSTRACT Automated rRNA intergenic spacer analysis (ARISA) was used to characterise bacterial (B-ARISA) and fungal (F-ARISA) communities from different soil types. The 16S-23S intergenic spacer region from the bacterial rRNA operon was amplified from total soil community DNA for B-ARISA. Similarly, the two internal transcribed spacers and the 5.8S rRNA gene (ITS1-5.8S-ITS2) from the fungal rRNA operon were amplified from total soil community DNA for F-ARISA. Universal fluorescence-labeled primers were used for the PCRs, and fragments of between 200 and 1,200 bp were resolved on denaturing polyacrylamide gels by use of an automated sequencer with laser detection. Methodological (DNA extracti…
Biodiversity-functioning relations in microorganisms
The role of microorganisms as key components in the functioning of ecosystems and biodiversity is discussed. The latest methodologies developed to study microbial diversity and functioning of ecosystems are considered, as DNA extraction and isotope labeling, fluorescent in situ hybridization and microautoradiography, and tracking of a substrate labeled with a stable isotope. Investigations related to correlations between microbial diversity and functioning in situ are considered. An example is illustrated of a correlation of erosion of microbial diversity of natural microbial community in prairie soil and erosion of species diversity in an ecosystem.
Monitoring complex bacterial communities using culture-independent molecular techniques: application to soil environment
Over the last decade, important advances in molecular biology led to the development of culture-independent approaches to describing bacterial communities. These new strategies, based on the analysis of DNA directly extracted from environmental samples, circumvent the steps of isolation and culturing of bacteria, which are known for their selectivity leading to a non-representative view of the extent of bacterial diversity. This review provides an overview of the potentials and limitations of some molecular approaches currently used in microbial ecology. Examples of applications to the study of indigenous soil microbial community illustrate the feasibility and the power of such approaches.