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Nonlinear Dynamics and Spatial Heterogeneity in Flowing Suspensions of Swimming Microorganisms

Vendredi 6 novembre 2015 14:00 - Duree : 1 heure
Lieu : Conference room - LIPhy - Bât E - 140 Avenue de la Physique - St Martin d’Hères. Accès par interphone, appeler le secrétariat

Orateur : Roberto RUSCONI (Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, USA)

The vast majority of microorganisms experience fluid flow[1], whether turbulent flow in aquatic and industrial systems, or laminar flow in the human body and medical devices. Common to all flow regimes is hydrodynamic shear, which generates forces and torques on cells. In the absence of shear, motile microorganisms explore their environment with random-walk swimming patterns, resulting in diffusive transport, but little is known about the effects of fluid flow on their navigation and spatial distribution. Using microfluidics, I will show that swimming microorganisms can be trapped in regions of high shear, where the hydrodynamic torque preferentially aligns them in the flow direction, quenching their migration across streamlines[2]. This is a robust phenomenon, which can result in depletion of cells from the low-shear regions of the flow within only a few seconds and which does not require any cell-surface interaction to induce the observed heterogeneous distributions. A shear flow can have even more unpredictable effects on motile phytoplankton cells, as the spatial distribution of these microorganisms is also governed by their swimming style. These observations encompass a rich set of dynamics that emerges from the interaction of microbial motility, morphology and fluid flow and that can affect the microscale distribution of microorganisms in the environment.

[1] Rusconi R, Stocker R, “Microbes in flow”, Curr. Op. Microbiol. 25, 1–8 (2015).

[2] Rusconi R, Guasto JS, Stocker R, “Bacterial transport suppressed by fluid shear”, Nature Physics 10, 212–217 (2014).

Contact : sigolene.lecuyer@ujf-grenoble.fr

Discipline évènement : (Biologie / Chimie)
Entité organisatrice : (LIPhy)
Nature évènement : (Séminaire)
Evènement répétitif : (Séminaire Mat. Molle/grise)
Site de l'évènement : Domaine Universitaire de St Martin d’Hères

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