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Isabelle Eisenmann

University of Amsterdam

Isabelle is a postdoctoral researcher at the University of Amsterdam, where she studies the dynamics of photosynthetic microorganisms. Understanding their behavior not only allows to use them as a playground for active matter investigation but also sheds light on how this critical class of organisms adapts to its environment. She is an experimental physicist working at the frontier of physics and biology, in collaboration with theoreticians, biologists and chemists. She completed her PhD at LPENS in Paris under the supervision of Raphaël Jeanneret and Nicolas Desprat and was trained at Ecole Centrale Paris and Institut Pierre-Gilles de Gennes.

Drops, branches, pearls and waves: light-induced collective phenomena in phototactic microalgae

Chlamydomonas reinhardtii is a model micro-algae that is both photosynthetic and phototactic. As such, it uses light not only as an energy source but also as a cue to orient in space. In suspensions of C.reinhardtii, light thus reinforces interactions in many ways: cells generate flows, but they also alter light propagation and medium composition. Flows, light and chemicals in turn influence their motion. These complex interactions can drive the formation of patterns at macroscopic scales. In this talk I will explain how phototaxis can be harnessed to induce collective behaviors of these different nature in suspensions of C.reinhardtii. In each case I will aim to make a clear connection between the macroscopic observations and what happens at the micro-scale, and highlight the biological relevance of the phenomenon.