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Aragno, Michel

Nom
Aragno, Michel
Affiliation principale
Email
Michel.Aragno@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/753

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  • Publication
    Accès libre
    Nitrogen fertiliser rate affects the frequency of nitrate-dissimilating Pseudomonas spp. in the rhizosphere of Lolium perenne grown under elevated pCO2 (Swiss FACE)
    (2005)
    Fromin, Nathalie
    ;
    Tarnawski, Sonia Estelle
    ;
    Roussel-Delif, L.
    ;
    Hamelin, Jérôme
    ;
    Baggs, E.M.
    ;
    Aragno, Michel 
    The effect of elevated pCO2 (60 Pa) on the frequency of nitrate-dissimilating Pseudomonas (NDP) was investigated in the rhizosphere of fertilised Lolium perenne swards in the Swiss Free Air Carbon dioxide Enrichment (FACE) experiment. Numbers of cultivable root-associated Pseudomonas were greater under elevated (60 Pa) than under ambient (36 Pa) pCO2 in both high and low N-fertilised swards. For both pCO2 conditions, the NDP frequency decreased with closer root proximity to L. perenne roots in low fertilised swards. Anyway, in high N swards the NDP frequency was similar in root and soil fractions. Thus, N availability may be a major factor influencing NDP populations under elevated pCO2, most likely due to increased competition for N between plant and nitrate-dissimilating bacteria.
  • Publication
    Accès libre
    Examination of Gould’s modified S1 (mS1) selective medium and Angle’s non-selective medium for describing the diversity of Pseudomonas spp. in soil and root environments
    (2003)
    Tarnawski, Sonia Estelle
    ;
    Hamelin, Jérôme
    ;
    Locatelli, Laurent
    ;
    Aragno, Michel 
    ;
    Fromin, Nathalie
    Studies on the diversity of environmental culturable Pseudomonas populations are dependent on the isolation procedure. This procedure includes the use of selective media which may influence the recovery of strains and thus the diversity described. In this study, we assessed the use of two agar isolation media for describing the diversity of soil- and root-inhabiting Pseudomonas associated with the perennial grass Molinia coerulea. A total of 382 Pseudomonas strains were recovered on either non-selective Angle’s medium, or on Gould’s modified S1 (mS1) Pseudomonas-selective medium. Their diversity was assessed by restriction analysis of PCR (polymerase chain reaction)-amplified 16S–23S rDNA internal transcript spacer sequences. The comparison of mS1- and Angle-recovered populations showed that the use of mS1 selective medium led to an underestimation of both Pseudomonas counts and diversity, especially in the soil environment.
  • Publication
    Accès libre
    Specific PCR Amplification for the Genus Pseudomonas Targeting the 3′ Half of 16S rDNA and the Whole 16S–23S rDNA Spacer
    (2002)
    Locatelli, Laurent
    ;
    Tarnawski, Sonia Estelle
    ;
    Hamelin, Jérôme
    ;
    Rossi, Pierre
    ;
    Aragno, Michel 
    ;
    Fromin, Nathalie
    A PCR protocol was developed for the selective amplification of a segment of the ribosomal RNA operon in Pseudomonas strains. Two specific conserved sequences suitable for PCR priming were identified in the middle of the 16S rDNA and at the very beginning of the 23S rDNA respectively. As a result, amplified region includes the 3′ half of the 16S rDNA with the whole 16S–23S rRNA Internal Transcripted Spacer (ITS1) sequence. The specificity of the primer set was checked on sequence databases and validated on collection strains and on one hundred soil bacterial isolates. Our results showed that both collection, soil-inhabiting Pseudomonas and some Pseudomonas-related Azotobacter DNAs could be amplified. This specific PCR for the detection of Pseudomonas strains was in good agreement with colony hybridisation using a Pseudomonas-specific probe. The targeted segment is relevant for a characterisation at the species (16S rDNA) as well as at the infraspecific (ITS1) levels. This PCR-based approach offers promising potential for the characterisation of environmental Pseudomonas populations.