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Light Control of the Diffusion Coefficient of Active Fluids by Vourc'h, Thomas; Léopoldès, Julien; Peerhossaini, Hassan is a scholarly article available to read on EtoBox.

What is Light Control of the Diffusion Coefficient of Active Fluids about?

Active fluids refer to the fluids that contain self-propelled particles such as bacteria or micro-algae, whose properties differ fundamentally from the passive fluids. Such particles often exhibit an intermittent motion, with high-motility (run) periods broken by low-motility (tumble) periods. The average motion can be modified with external stresses, such as nutrient or light gradients, leading to a directed movement called chemotaxis and phototaxis, respectively. Using cyanobacterium Synechocystis sp.PCC 6803, a model micro-organism to study photosynthesis, we track the bacterial response to light stimuli, under isotropic and non-isotropic (directed) conditions. In particular, we investigate how the intermittent motility is influenced by illumination. We find that just after a rise in light intensity, the probability to be in the run state increases. This feature vanishes after a typical characteristic time of about 1 hour, when initial probability is recovered. Our results are well described by a mathematical model based on the linear response theory. When the perturbation is anisotropic, we observe a collective motion toward the light source (phototaxis). We show that the bias

Author

Vourc'h, Thomas; Léopoldès, Julien; Peerhossaini, Hassan

Published

2020

Language

EN