Seminar über aktuelle Fragen zur Dynamik komplexer Fluide: Light-regulated motility and collective behavior of photoactive microalgae

The accumulation of microbial active swimmers as clusters in the liquid medium or as a biofilm at an interface is an ubiquitous effect in systems with a high particle density.
In this talk, the recently discovered effect of light-regulated aggregation of planktonic Chlamydomonas reinhardtii cells in confinement is presented. The formation of a cluster
at low light intensities has been investigated using 2D particle tracking. This method allows not only for a description of the spatial distribution of several thousands of individual cells, but also for a quantitative analysis of their motility. The results reveal the dependency of the cell motility on the local cell density and the light intensity. Additionally, evidence will be presented that the accumulation of cells is not related to a known tactic behavior of the cells, but originates from an interplay of confinement
and light-regulated motility.