ESPCI web site
PhD defense on October 18th, 2018, 2:30pm, at the PMMH meeting room (Sorbonne Université, Barre Cassan, Bât. A 1er Étage, 7 Quai Saint Bernard, 75005 Paris).
Acoustic confinement of Escherichia coli: The impact on biofilm formation
Brownian or self-propelled particles in aqueous suspensions can be trapped by acoustic fields generated by piezoelectric transducers usually at frequencies in the Megahertz. The obtained confinement allows the study of rich collective behaviours like clustering or spreading dynamics in microgravity-like conditions. The acoustic field induces the levitation of self-propelled particles and provides secondary lateral forces to capture them at nodal planes. Here, we give a step forward in the field of confined active matter, reporting levitation experiments of bacterial suspensions of Escherichia coli. Clustering of living bacteria is monitored as a function of time, where different behaviours are clearly distinguished. Upon the removal of the acoustic signal,motile bacteria rapidly spread, impelled by their own swimming. Short term trapping of diverse bacteria phenotypes results in irreversible bacteria entanglements and in the formation of free-floating biofilms-like structures.
Jury:
Harold Auradou (FAST, Université Paris–Saclay) Rapporteur
Philippe Marmottant (LiPhy, Université de Grenoble Alpes) Rapporteur
Nelly Henry (LJP, Sorbonne Université) Examinatrice
Sophie Ramananarivo (LadHyX, Ecole Polytechnique) Examinatrice
Jean-Luc Aider (PMMH, ESPCI Paris) Invité
Jesus Carlos Ruiz-Suárez (CINVESTAV Monterrey) Invité
Ramiro Godoy-Diana (PMMH, ESPCI Paris) Directeur de thèse