Search results for "microorganism"
showing 10 items of 449 documents
Microalgae community structure analysis based on 18S rDNA amplification from DNA extracted directly from soil as a potential soil bioindicator
2005
International audience; Soil algae are photosynthetically active microorganisms showing changeable community structure, depending on the soil type, the agricultural practices and the application of pesticides. To characterise algal community structure, molecular approaches complementary to classical microbiological approaches based on the isolation and the culture of soil algae are required. Our study describes a polymerase chain reaction (PCR) approach targeting algal 18S rDNA sequences of desoxyribonucleic acid (DNA) samples extracted either from unialgal eukaryotic microalgae culture, complex assemblages of microalgae populations or natural soil communities. Our first results showed that…
Identification of Traits Implicated in the Rhizosphere Competence of Fluorescent Pseudomonads: Description of a Strategy Based on Population and Mode…
2009
E-book; International audience; The lack of consistency of the beneficial effects of inoculated fluorescent pseudomonads has often been related to their bad survival in the rhizosphere. In this review, we describe the strategy followed over the last decade to study traits involved in the rhizosphere competence of these bacteria. The diversity of indigenous populations associated with plant roots was first compared to that of populations associated with uncultivated soils in order to identify traits that discriminate these populations. The involvement of these bacterial traits in the rhizosphere competence was then assessed by comparing the competitiveness of a wild-type strain to that of mu…
DIAGSOL : development of a new functional marker of exposure to herbicides B-triketones in an agricultural soil
2020
Numerous herbicides target an enzyme found not only in weeds but also in « non-target organisms » such as microorganisms. This proof-of-concept study aims to use microbial gene encoding the targeted enzyme or the targeted enzyme itself as a marker for herbicide exposure in soils. The hppd gene and the encoded enzyme (HPPD; 4-hydroxyphenylpyruvate dioxygenase), targeted by B-triketone herbicides, are the subject of this study. In silico analyses reveal that the hppd gene is spread out in all bacterial phyla. Primers specific to this gene were designed. This primer pair is used to measure the abundance, the composition and the diversity of the hppd bacterial community in soil microcosms expos…
Réponse des interactions plante-sol aux régimes de précipitations
2018
Water availability governs terrestrial nutrient cycles by impacting the functioning of both plants and of soil microorganisms. The predicted changes in precipitation patterns (i.e. the magnitude and frequency of precipitation events) associated with climate change, will thus likely have important consequences on ecosystem functioning. Dry and seasonally dry ecosystems are particularly vulnerable to changes in precipitation patterns, as they are already constrained to a large extent by water availability. However, more mesic systems may also experience dry periods that may impact plant-soil functions. In this thesis, experiments in soil-only systems and plant-soil systems were used to gain i…
Costs-benfits trade-off in the intercation between Medicago truncatula and Pseudomonas fluorescens C7R12 across atmospheric carbon dioxide modulation
2011
The interactions between plants and soil microorganisms are mainly based on trophic relationships. The compounds exchanged represent cost for the organism produces them but a benefit for the one who receive those compounds. A mutualistic relation leads to stability in the cost-benefit balance resulting from a co-evolution between the two organisms. The cost corresponding for the release of carbon compounds by the plant would be offset by benefits in return corresponding for the activities of microorganisms that use them. We tested by an experimental way the effect of CO2 concentration on the interaction between M. truncatula and the bacterium P. fluorescens C7R12. The results allowed a best…
Rôle de la membrane plasmique dans la survie des microorganismes à la déshydratation : Contribution à l’optimisation de procédés de conservation des …
2010
Cette synthèse est consacrée au rôle de la membrane plasmique des microorganismes, à travers ses évolutions structurales et fonctionnelles, dans la survie à la déshydratation. Elle comprend une première partie dans laquelle sont regroupés les principaux résultats portant sur l’influence de la déshydratation sur la survie microbienne, sur le comportement membranaire in situ et sur les mécanismes physiques de la déstabilisation membranaire. La deuxième partie est consacrée à la transposition de cette compréhension aux applications de déshydratation industrielle des microorganismes. Elle porte sur le développement d’un procédé de déshydratation des microorganismes et sur la mise au point d’out…
Pourquoi faut-il se préoccuper de la toxicité des pesticides pour les microorganismes du sol ?
2017
EABIOmE INRA; Pourquoi faut-il se préoccuper de la toxicité des pesticides pour les microorganismes du sol ?
Étude de la biodégradation de l'herbicide acide 2.4-dichlorophénoxyacétique (2.4-D) dans des sols agricoles de la région de Constantine
2011
Les principaux facteurs conditionnant la biodégradation du 2,4-D dans trois sols agricoles algériens (45IB, 46BM et 47AA), notamment l'humidité et la température, ont été examinés. Les cinétiques de minéralisation de l'herbicide ont été déterminées par radiorespirométrie, qui consiste à piéger et estimer le 14C02 formé dans une solution de soude à l'aide d'un compteur à scintillation liquide. Les résultats obtenus confirment la présence de microorganismes dégradants le 2,4-D et la biodégradation de cet herbicide semble dépendre essentiellement des propriétés physicochimiques intrinsèques des sols notamment la teneur en argile et MgO. Le sol 46BM, caractérisé par de faibles quantités en sabl…