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18 décembre 2018: 1 événement

  • Séminaires Invités

    Mardi 18 décembre 2018 14:00-15:30 - Benedikt SABASS - Institute of Complex systems, Forschungzentrum Jülich, Germany

    Bacterial Surface Migration : Force Measurement and Modelling

    Résumé : Generation and control of mechanical forces are essential for a wide range of bacterial behaviors including surface migration and colony formation and also play a role for infection by Gram-negative pathogens. Many bacteria employ retractable type-IV pili to generate these nanoscopic forces. Since it is difficult to measure such small forces in a perturbationless fashion, little is known about how bacteria regulate or adapt their force generation by pili.
    Here, I present experimental and theoretical studies of bacterial surface migration. First, I summarize a study of bacterial cell-substrate traction with Myxococcus xanthus as a model organism. Measurements show that during migration, individual type-IV pili exert forces around 50 pN deforming the substrate beneath the bacteria. However, when M. xanthus aggregates into groups, forces appear upregulated and pili exert more than twice the forces measured with individual cells. Nevertheless, pilus dynamics remain uncoordinated in groups leading to random tugging with autocorrelation times on the order of one minute.
    After discussing experimental findings, I present a model describing the effects of surface properties on bacterial migration. The model predicts a non-linear dependence of migration speed and mean square displacement on substrate properties, which is in accordance with experimental data. The essence of these effects is explained by an analytical theory.

    contact : Delpine Débarre

    Lieu : LIPhy, conference room - 140 Avenue de la Physique 38402 Saint Martin d’Hères

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