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Complex Dynamics of Swarming Bacteria in Three Dimensions (3D Swarming)
Date du début: 1 oct. 2012, Date de fin: 30 sept. 2016 PROJET  TERMINÉ 

Motile bacteria are able to colonize surfaces using various types of motility. ‘Bacterial swarming’ is the most rapid method, involving an organized, hyperflagellated-based cell motion and collective secretion of bio-surfactants. During swarming, bacteria exploit hydrodynamic interactions; they move in whirls and jets similarly to flocks of birds and schools of fish. Hundreds of cells migrate on the surface in dynamic clusters and form either a single layer or multiple layers, depending on the strain and growth conditions. Past work, which used particle tracking methods to analyze cell trajectories, showed clear group benefits. However, those studies were largely limited to quasi two-dimensional imprecise assumptions and to extreme sample manipulations, all of which combined to yield unnatural habitats. Consequently, it is not clear how swarming cells migrate in a real three-dimensional colony. Here I will study bacterial swarming in unconstrained natural habitats. The methodology is based on mixing green fluorescent protein (GFP)-labelled motile bacteria with wild type bacteria and tracking their three-dimensional trajectories using a specially designed microscope setup and sophisticated computer programs. This setup will enable me to explore whether the movement of a single cell within a multilayered swarming colony is influenced by its neighbors and to discover whether groups of cells tend to disperse or to build small localized sub-communities if conditions are adverse. Sophisticated data analysis will clarify whether bacteria move only within one layer inside the multilayered swarm or whether they migrate up and down, switching from layer to layer. By performing the experiment with added antibiotics, the results are expected to show how bacteria join and collectively benefit for the survival of the strain.