Search results for "pseudomonas fluorescens"
showing 10 items of 56 documents
The establishment of an introduced community of fluorescent pseudomonads in the soil and in the rhizosphere is affected by the soil type
1999
Indigenous populations of fluorescent pseudomonads were previously shown to vary in two different soils (Châteaurenard and Dijon) and in the rhizosphere of a plant species (Linum usitatissimum L.) cultivated in these two soils. These differences could be related to the soil type and to their crop history. In the present study, the influence of the soil type on the diversity of fluorescent pseudomonads in bulk and rhizospheric soils was evaluated. The soils of Châteaurenard and Dijon were sterilized before being inoculated with the same community of fluorescent pseudomonads. Bacterial isolates from bulk and rhizospheric soils were characterized on the basis of their repetitive extragenic pal…
Interaction between Medicago truncatula and Pseudomonas fluorescens: evaluation of costs and benefits across an elevated atmospheric CO2.
2012
10 pages; International audience; Soil microorganisms play a key role in both plants nutrition and health. Their relation with plant varies from mutualism to parasitism, according to the balance of costs and benefits for the two partners of the interaction. These interactions involved the liberation of plant organic compounds via rhizodeposition. Modification of atmospheric CO2 concentration may affect rhizodeposition and as a consequence trophic interactions that bind plants and microorganisms. Positive effect of elevated CO2 on plants are rather well known but consequences for micoorganisms and their interactions with plants are still poorly understood. A gnotobiotic system has been devel…
Biosorption lead(II) and nikel(II) from an aqueous solution by bacterial biomass
2010
Biosorption lead(II) and nikel(II) from an aqueous solution by bacterial biomass The optimum conditions for biosorption of Pb(II) and Ni(II) from aqueous solution were investigated, by using living and nonliving Pseudomonas fluorescens and Bacillus pumilus isolated from wastewater treatment plant. It was found that the optimum pH for Pb(II) removal by living and nonliving cells was 6.0, while 7.0 for Ni(II) removal. At the optimal conditions, metal ion biosorption was increased as the initial metal concentration increased. The binding capacity by living cells is significantly higher than that of nonliving cells at tested conditions. The maximum biosorption capacities for lead and nickel by …
Survival in the soil of the ectomycorrhizal fungus Laccaria bicolor and the effects of a mycorrhiza helper Pseudomonas fluorescens
2001
In disinfected forest nursery soils, inoculating Douglas fir (Pseudotsuga menziesii) seedlings with the ectomycorrhizal fungal strain Laccaria bicolor S238N significantly increases tree growth after outplantating. However, the success of the inoculation depends on survival of the fungal inoculum in the soil during the pre-symbiotic life of the fungus. We followed the survival of L. bicolor S238N in autoclaved nursery soil in the glasshouse, and under gnotobiotic conditions in autoclaved or γ-irradiated nursery soil. We also studied the effect of the mycorrhiza helper bacterium Pseudomonas fluorescens BBc6R8, which promotes the Douglas fir-L. bicolor S238N symbiosis, on fungal viability. In …
Establishment of tools for investigating pyoverdine impact on iron homeostasis and plant defense responses
2013
Iron, the fourth major element in the Earth crust, is essential for growth and development of living organisms. However, due to its low solubility in the soil, it is weakly available for plants and micro-organisms. To efficiently assimilate iron, living organisms have evolved specific strategies. In plants such as Arabidopsis thaliana three trans-membrane proteins are involved in iron assimilation while in bacteria such as Pseudomonas fluorescens iron is taken up from the soil thanks to molecules displaying high affinity for iron called siderophores. It has been recently shown that pyoverdine, the major siderophore of the beneficial bacterium Pseudomonas fluorescens, is assimilated by A. th…
Iron acquisition from Fe-pyoverdine by Arabidopsis thaliana.
2007
Taking into account the strong iron competition in the rhizosphere and the high affinity of pyoverdines for Fe(III), these molecules are expected to interfere with the iron nutrition of plants, as they do with rhizospheric microbes. The impact of Fe-pyoverdine on iron content of Arabidopsis thaliana was compared with that of Fe-EDTA. Iron chelated to pyoverdine was incorporated in a more efficient way than when chelated to EDTA, leading to increased plant growth of the wild type. A transgenic line of A. thaliana overexpressing ferritin showed a higher iron content than the wild type when supplemented with Fe-EDTA but a lower iron content when supplemented with Fe-pyoverdine despite its inc…
Analysis of the role of nitric oxide (NO) in the cross‐regulation between immunity, growth and iron homeostasis in plants
2019
Studies performed in our Agroecology Department show that the immune response of plants is linked to their iron nutrition and is modulated by pyoverdine, a siderophore produced by the plant beneficial rhizobacteria Pseudomonas fluorescens C7R12. Accordingly, Arabidopsis thaliana plantlets exposed to iron deficiency and treated with pyoverdine in its iron non‐chelated structure (apo‐pyo) show an enhanced growth but a decreased immune response capacity. We hypothesize that nitric oxide (NO), a universal signaling molecule, is a key component of the regulation of the immune response in plants exposed to apo‐pyo and to the C7R12 strain. We checked by fluorescence microscopy that NO is actually …
Kinetics of vinyl acetate biodegradation by Pseudomonas fluorescens PCM 2123
2018
Abstract The microbial degradation of vinyl acetate (VA) by Pseudomonas fluorescens PCM 2123 strain was studied in both batch and continuous modes. The purpose of the experiments was to determine the kinetic model of the cell growth and biodegradation rate of vinyl acetate (VA), which was the sole carbon and energy source for tested microorganisms. The experiments, carried out in a batch reactor for several initial concentrations of growth substrate in the liquid phase ranging from 18.6 to 373 gsubstrate·m−3 (gs·m−3) made it possible to choose the kinetic model and to estimate its constants. The Haldane inhibitory model with the values of constants: μm = 0.1202 h−1, KS = 17.195 gs·m−3, Ki =…
Physical factors affecting the production of amylase from Bacillus species isolated from natural environment
2014
The aim of conducted research was to determine influence of metabolites produced by Pseudomonas fluorescens on the growth of 4 phytopathogenic strains of Rhizoctonia solani marked R1, R2, R3 and R4 which infect sugar beetroot. The antagonistic properties were assessed with the culture-plate method on PDA medium for P. fluorescens cultured for 4, 6 8, 10 and 24 hours at 25 o C for 5 days. The fungistatic activity of P. fluorescens was determined against the growth rate index and the rate of mycelial growth inhibition. Obtained results prove, that Rhizoctonia spp. strains were both sensitive and resistant to metabolites produced by P. fluorescens. The highest inhibition of the linear growth o…
Colonization pattern of primary tomato roots by Pseudomonas fluorescens A6RI characterized by dilution plating, flow cytometry, fluorescence, confoca…
2004
Early colonization of primary tomato roots, grown in vitro, by Pseudomonas fluorescens A6RI, introduced by seed bacterization, was monitored for 7 days in three different root zones (zone A, apex+elongation+young hairy zone; zone B, hairy zone; zone C, old hairy zone+collar). Bacterial quantification was assessed by enumeration of (i) colony forming units (cfu) after dilution plating and of (ii) total bacterial cells by flow cytometry. Bacterial distribution and organization in the root zones were analyzed by fluorescence, confocal and scanning electron microscopy. For all sampling dates and zones, the densities of total bacterial cells were significantly higher than those of the cfu. The k…