Berlin 2018 – scientific programme

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BP: Fachverband Biologische Physik

BP 21: Microswimmers (joint session BP/CPP/DY)

BP 21.9: Talk

Wednesday, March 14, 2018, 17:15–17:30, H 1028

Dynamics of chemotactic and chemokinetic bacterial populations — •Theresa Jakuszeit¹, James Lindsey-Jones¹, François J. Peaudecerf², and Ottavio A. Croze¹ — ¹Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom — ²Institute of Environmental Engineering, ETH Zürich, Stefano-Franscini-Platz 5, 8093 Zürich, Switzerland

Several motile bacteria are able to sense chemical gradients much larger than their own size, and perform a random walk biased up attractant gradients (‘chemotaxis’) by varying their reorientation rate. In addition to this well-known chemotactic behaviour, several soil and marine bacterial species are known to modify their swimming speed according to the local concentration of chemoattractant (‘chemokinesis’). Therefore, a chemical field of attractant induces a spatially varying swimming speed, which results in a drift towards lower attractant concentrations – contrary to the drift created by chemotaxis.

Here, to explore the biological benefits of chemokinesis and investigate its impact on the chemotactic response, we extend a Keller-Segel type model to include a dependence of the swimming speed on the attractant concentration. Even though chemokinesis on its own results in a dispersion of the population away from high attractant concentrations, it can not only enhance the chemotactic response but also modify it qualitatively. We apply the model to predict the dynamics of bacteria capable of chemokinesis and chemotaxis in experimentally inspired chemoattractant fields, such as those generated in capillary migration assays and around environmental nutrient sources.