0000000000104640
AUTHOR
Sylvie Nazaret
Impact of the use of wastewater for irrigation of cultivated plots on the soil microbiological quality in semi-arid zone (Tunisia): approaches at the plot and catchment area scales
Affiche, résumé. Session AS: Agricultural Soils: Biodiversity and Functioning; International audience
La biologie moléculaire en écologie microbienne du sol : application à l'analyse de la structure des communautés bactériennes
National audience
Impact of inoculation with the phytostimulatory PGPR Azospirillum lipoferum CRT1 on the genetic structure of the rhizobacterial community of field-grown maize
International audience; The phytostimulatory PGPR Azospirillum lipoferum CRT1 was inoculated to maize seeds and the impact on the genetic structure of the rhizobacterial community in the field was determined during maize growth by Automated Ribosomal Intergenic Spacer Analysis (ARISA) of rhizosphere DNA extracts. ARISA fingerprints could differ from one plant to the next as well as from one sampling to the next. Inoculation with strain CRT1 enhanced plant-to-plant variability of the ARISA fingerprints and caused a statistically significant shift in the composition of the indigenous rhizobacterial community at the first two samplings. This is the first study on the ecological impact of Azosp…
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…
Distribution de bactéries pathogènes dans les sols évaluée par PCR quantitative en temps réel
National audience
Distribution des bactéries pathogènes dans les sols évaluée par PCR quantitative en temps réel
National audience
Response of soil bacteria to Hg (II) in relation to soil characteristics and cell location
The response of indigenous bacterial communities to the addition of inorganic mercury (50 μM of Hg(II)) was compared over a 30 day period in four soils of contrasting properties. Hg(II) impact was estimated by following population dynamics of viable heterotrophic bacteria (VH) and mercury resistant bacteria (HgR) by indirect enumeration in unfractionated soil and in the inner and outer parts of soil aggregates obtained by successive washings. Numbers of VH bacteria in unfractionated soils were not affected by mercury in any of the studied soils, whereas an increase in resistant bacteria was observed in all of them. The lag phase before the increase of HgR bacteria and the magnitude of the e…
Heterogeneous cell density and genetic structure of bacterial pools associated with various microenvironments as determined by enumeration and DNA fingerprinting approach (RISA)
International audience
Freshwater bateria can methylate selenium through the tiopurine methyltransferase pathway
International audience
Characterization of a novel selenium methyltransferase from freshwater bacteria showing strong similarities with the calicheamicin methyltransferase
A novel group of Se-methyltransferases is presented. The genetic determinant, named mmtA, which revealed this group was isolated from selenite and selenate-resistant freshwater bacteria. E. coli expressing mmtA and grown with a Se supplement emitted dimethyl selenide (DMSe) and dimethyl diselenide (DMDSe). Phylogenetic analysis divided MmtA-like bacterial sequences into two clusters, one grouping MmtA with S- and O-methyltransferases, and one grouping UbiE C-methyltransferases. Se methylation by some of these MmtA phyletic neighbours was investigated.
Membres du comité d’organisation scientifique
EA BIOME INRA; National audience
The typology of organic wastes influences dose-response relationships between sulfonamide residues and antibiotic resistance genes in amended soils.
National audience
Impact of soil fertilization with organic amendments on the dissemination of antibiotic resistance in cultivated soils
National audience
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.
Methylation of inorganic selenium by the bacterial thiopurine methyltransferase
International audience
Shifts in diversity and microscale distribution of the adapted bacterial phenotypes due to Hg(II) spiking in soil.
In a previous experiment [Ranjard et al. (2000) FEMS Microbiol Ecol 31:107–115], the spatial heterogeneity of a mercury impact on soil bacterial community was revealed by an increase of mercury-resistant (HgR) bacterial numbers in the outer fraction and the sand fractions when compared to those in the silt fractions. The objectives of the present study were (i) to investigate whether mercury exposure affects the diversity and the distribution within the various fractions of the HgR populations and (ii) to evaluate the contribution of the HgR populations to the overall community adaptation. A total of 236 strains isolated before (104 isolates) and 30 days (132 isolates) after spiking were ch…
Natural soil reservoirs for human pathogenic and fecal indicator bacteria
Prod ? EA UB INRA BIOME; International audience; résumé du livre : Environmental microbiology, the study of the roles that microbes play in all planetary environments, is one of the most important areas of scientific research. The The Manual of Environmental Microbiology, Fourth Edition, provides comprehensive coverage of this critical and growing field. Thoroughly updated and revised, the Manuall is the definitive reference for information on microbes in air, water, and soil and their impact on human health and welfare. Written in accessible, clear prose, the manual covers four broad areas: general methodologies, environmental public health microbiology, microbial ecology, and biodegradati…
L'impact du mercure sur les bactéries telluriques
Les polluants toxiques, tels que le mercure, affectent largement les ecosystemes aquatiques, mais aussi les sols. Comment les bacteries telluriques reagissent-elles ?
Soil microbial community response to a selenium chronic exposure
International audience
Soils as reservoir of opportunistic human material pathogens and impact of agricultural practices
Affiche, résumé; National audience
A soil microscale study to reveal the heterogeneity of Hg (II) impact on indigenous bacteria by quantification of adapted phenotypes and analysis of community DNA fingerprints
International audience