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Filippidou, Sevasti

Nom
Filippidou, Sevasti
Affiliation principale
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https://libra.unine.ch/handle/123456789/759

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  • Publication
    Accès libre
    Exploiting the fungal highway: development of a novel tool for the in situ isolation of bacteria migrating along fungal mycelium
    (2015)
    Simon, Anaele 
    ;
    Bindschedler, Saskia 
    ;
    Job, Daniel 
    ;
    Wick, Lukas Y.
    ;
    Filippidou, Sevasti 
    ;
    Kooli, Wafa M.
    ;
    Verrecchia, Eric P.
    ;
    Junier, Pilar 
    Fungi and bacteria form various associations that are central to numerous environmental processes. In the so-called fungal highway, bacteria disperse along fungal mycelium. We developed a novel tool for the in situ isolation of bacteria moving along fungal hyphae as well as for the recovery of fungi potentially involved in dispersal, both of which are attracted towards a target culture medium. We present the validation and the results of the first in situ test. Couples of fungi and bacteria were isolated from soil. Amongst the enriched organisms, we identified several species of fast-growing fungi (Fusarium sp. and Chaetomium sp.), as well as various potentially associated bacterial groups, including Variovorax soli, Olivibacter soli, Acinetobacter calcoaceticus, and several species of the genera Stenotrophomonas, Achromobacter and Ochrobactrum. Migration of bacteria along fungal hyphae across a discontinuous medium was confirmed in most of the cases. Although the majority of the bacteria for which migration was confirmed were also positive for flagellar motility, not all motile bacteria dispersed using their potential fungal partner. In addition, the importance of hydrophobicity of the fungal mycelial surface was confirmed. Future applications of the columns include targeting different types of microorganisms and their interactions, either by enrichment or by state of the art molecular biological methods.
  • Publication
    Accès libre
    Gains of Bacterial Flagellar Motility in a Fungal World
    Pion, Martin
    ;
    Bshary, Redouan 
    ;
    Bindschedler, Saskia 
    ;
    Filippidou, Sevasti 
    ;
    Wick, Lukas Y
    ;
    Job, Daniel 
    ;
    Junier, Pilar 
    The maintenance of energetically costly flagella by bacteria in non-water-saturated media, such as soil, still presents an evolutionary conundrum. Potential explanations have focused on rare flooding events allowing dispersal. Such scenarios, however, overlook bacterial dispersal along mycelia as a possible transport mechanism in soils. The hypothesis tested in this study is that dispersal along fungal hyphae may lead to an increase in the fitness of flagellated bacteria and thus offer an alternative explanation for the maintenance of flagella even in unsaturated soils. Dispersal along fungal hyphae was shown for a diverse array of motile bacteria. To measure the fitness effect of dispersal, additional experiments were conducted in a model system mimicking limited dispersal, using Pseudomonas putida KT2440 and its nonflagellated (ΔfliM) isogenic mutant in the absence or presence of Morchella crassipes mycelia. In the absence of the fungus, flagellar motility was beneficial solely under conditions of water saturation allowing dispersal, while under conditions limiting dispersal, the nonflagellated mutant exhibited a higher level of fitness than the wild-type strain. In contrast, in the presence of a mycelial network under conditions limiting dispersal, the flagellated strain was able to disperse using the mycelial network and had a higher level of fitness than the mutant. On the basis of these results, we propose that the benefit of mycelium-associated dispersal helps explain the persistence of flagellar motility in non-water-saturated environments.