Search results for "relation sol microorganisme"
showing 8 items of 8 documents
Evidence for shifts in the structure and abundance of the microbial community in a long-term PCB-contaminated soil under bioremediation.
2011
International audience; Although the impact of bioremediation of PCB-contaminated sites on the indigenous microbial community is a key question for soil restoration, it remains poorly understood. Therefore, a small-scale bioremediation assay made of (a) a biostimulation treatment with carvone, soya lecithin and xylose and (b) two bioaugmentation treatments, one with a TSZ7 mixed culture and another with a Rhodococcus sp. Z6 pure strain was set up. Changes in the structure of the global soil microbial community and in the abundances of different taxonomic phyla were monitored using ribosomal intergenic spacer analysis (RISA) and real-time PCR. After an 18-month treatment, the structure of th…
Effect of primary mild stresses on resilience and resistance of the nitrate reducer community to a subsequent severe stress
2008
International audience; The factors regulating soil microbial stability (e.g. resistance and resilience) are poorly understood, even though microorganisms are essential for ecosystem functioning. In this study, we tested whether a functional microbial community subjected to different primary mild stresses was equally resistant or resilient to a subsequent severe stress. The nitrate reducers were selected as model community and analysed in terms of nitrate reduction rates and genetic structure by narG PCR-restriction fragment length polymorphism fingerprinting. Heat, copper and atrazine were used as primary stresses and mercury at a high concentration as a severe stress. None of the primary …
Copper Dynamics and Impact on Microbial Communities in Soils of Variable Organic Status
2008
International audience; The effect of soil organic status on copper impact was investigated by means of a microcosm study carried out on a vineyard soil that had been amended with varying types of organic matter during a previous long-term field experiment. Soil microcosms were contaminated at 250 mg Cu kg−1 and incubated for 35 days. Copper distribution and dynamics were assessed in the solid matrix by a sequential extraction procedure and in the soil solution by measuring total and free exchangeable copper concentrations. Copper bioavailability was also measured with a whole-cell biosensor. Modifications of microbial communities were assessed by means of biomass-C measurements and charact…
The dynamics of soil bacterial community structure in response to yearly repeated agricultural copper treatments
2008
International audience; The annual dynamics of soil bacterial community structure, including early, dose-dependent and transient modifications, was observed consecutively at different levels of copper contamination (high: 48 kg Cu ha−1, low: 16 kg Cu ha−1) repeated yearly over a three-year field experiment. Repeated low-level Cu contamination led to an increase in community stability to metal stress without a long-term shift in the population structure, whereas repeated high-level Cu contamination induced a novel and stable bacterial community structure. Furthermore, field experimentation highlighted that episodic climatic stress can modulate copper impact by enhancing community stability.
Response of soil bacterial community structure to successive perturbations of different types and intensities
2008
SummaryIn soil, genetic structure modifications of indigenousbacterial community consecutively to a severe stress(mercury contamination) were delayed when thecommunity was pre-exposed to various minor per-turbations (heat, copper and atrazine). Such minorperturbations induced transitory community struc-ture modifications leading to an increase of commu-nity stability towards a severe mercury stress. Theseresults illustrated well the short-term pre-adaptationprocess for bacterial community hypothesizing thatcommunity submitted to perturbations become moreresistant to withstand another stress. Compared with other environmental matrices of the bio-sphere, soils are considered as the main reservo…
Assessing genetic structure and diversity of airborne bacterial communities by DNA fingerprinting and 16S rDNA clone library
2005
Abstract The density, genetic structure and diversity of airborne bacterial communities were assessed in the outdoor atmosphere. Two air samples were collected on the same location (north of France) at two dates (March 2003 (sample1) and May 2003 (sample 2)). Molecular culture-independent methods were used to characterise airborne bacterial communities regardless of the cell culturability. The automated-ribosomal intergenic spacer analysis (A-RISA) was performed to characterise the community structure in each sample. For both sampling dates, complex A-RISA patterns were observed suggesting a highly diverse community structure, comparable to those found in soil, water or sediment environment…
Changes in gene expression during adaptation of Listeria monocytogenes to the soil environment
2011
project SEST 009; International audience; Listeria monocytogenes is a ubiquitous opportunistic pathogen responsible for listeriosis. In order to study the processes underlying its ability to adapt to the soil environment, whole-genome arrays were used to analyse transcriptome modifications 15 minutes, 30 minutes and 18 h after inoculation of L. monocytogenes EGD-e in soil extracts. Growth was observed within the first day of incubation and large numbers were still detected in soil extract and soil microcosms one year after the start of the experiment. Major transcriptional reprofiling was observed. Nutrient acquisition mechanisms (phosphoenolpyruvate-dependent phosphotransferase systems and…
Protein and DNA fingerprinting of a soil bacterial community inoculated into three different sterile soils
2007
The functional and genetic structures of a soil bacterial community were characterized after inoculation into three different sterile soils using a protein and DNA fingerprinting method, respectively. Principal component analysis (PCA) of profiles revealed that, depending on soil characteristics, bacterial communities with similar genetic structures harbored different functional structures and thus could potentially be of differing ecological significance for soil functioning. Co-inertia analysis between protein fingerprinting data and the corresponding sets of soil physicochemical characteristics demonstrated the correlation between the functional structure of the bacterial community and s…