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Junier, Pilar

Nom
Junier, Pilar
Affiliation principale
Fonction
Professeure assistante
Email
pilar.junier@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/362

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  • Publication
    Accès libre
    Genetic diversity of cyanobacterial communities in Lake Kinneret (Israel) using 16S rRNA gene, psbA and ntcA sequence analyses
    (2007)
    Junier, Pilar 
    ;
    Witzel, Karl-Paul
    ;
    Hadas, Ora
    The genetic diversity of cyanobacterial communities was studied at various depths in Lake Kinneret (Israel). Denaturing gradient gel electrophoresis (DGGE) of specific 16S rRNA gene PCR products showed significant differences in the cyanobacterial community structure between epi- and hypolimnetic waters. Sequences of clone libraries prepared from 16S rRNA gene PCR products from epi- and hypolimnion revealed the presence of at least 11 different groups of cyanobacteria. Clones related to the unicellular cyanobacteria (Chroococcales and picocyanobacteria) dominated the clone libraries from both depths. New primers to amplify the gene coding for the photosystem II reaction centre (psbA) and the nitrogen regulator gene (ntcA) of cyanobacteria were developed and used for further characterization of the cyanobacterial communities from the lake. Sequences of psbA amplicons clustered with those from 2 different groups of marine Synechococcus and Chroococcales. Cloned ntcA amplicons from the lake were closely related and did not cluster with sequences from cultured cyanobacteria or other environmental sequences from this gene. All the molecular markers analyzed here showed similarity to sequences from some groups of cyanobacteria in the lake and those so far found in marine habitats.
  • Publication
    Accès libre
    Isolation and characterization of oxalotrophic bacteria from tropical soils
    Bravo, Daniel 
    ;
    Braissant, Olivier
    ;
    Cailleau, Guillaume 
    ;
    Verrecchia, Eric 
    ;
    Junier, Pilar 
    The oxalate–carbonate pathway (OCP) is a biogeochemical set of reactions that involves the conversion of atmospheric CO2 fixed by plants into biomass and, after the biological recycling of calcium oxalate by fungi and bacteria, into calcium carbonate in terrestrial environments. Oxalotrophic bacteria are a key element of this process because of their ability to oxidize calcium oxalate. However, the diversity and alternative carbon sources of oxalotrophs participating to this pathway are unknown. Therefore, the aim of this study was to characterize oxalotrophic bacteria in tropical OCP systems from Bolivia, India, and Cameroon. Ninety-five oxalotrophic strains were isolated and identified by sequencing of the 16S rRNA gene. Four genera corresponded to newly reported oxalotrophs (Afipia, Polaromonas, Humihabitans, and Psychrobacillus). Ten strains were selected to perform a more detailed characterization. Kinetic curves and microcalorimetry analyses showed that Variovorax soli C18 has the highest oxalate consumption rate with 0.240 μM h-1. Moreover, Streptomyces achromogenes A9 displays the highest metabolic plasticity. This study highlights the phylogenetic and physiological diversity of oxalotrophic bacteria in tropical soils under the influence of the oxalate–carbonate pathway.