Dresden 2017 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 54: Statistical Physics of Biological Systems I (Joint Session BP/DY)
BP 54.1: Vortrag
Donnerstag, 23. März 2017, 15:00–15:15, ZEU 250
Inference of chemotactic strategies of E. coli and Pseudonomas putida using Kramers-Moyal coefficients — •Maximilian Seyrich1, Oliver Pohl1, Marius Hintsche2, Zahra Alirezaei2, Carsten Beta2, and Holger Stark1 — 1Institut für Theoretische Physik, Technische Universität Berlin, 10623 Berlin, Germany — 2Institut für Physik und Astronomie, Universität Potsdam, 14476 Potsdam, Germany
Bacteria like E. coli and Pseudomonas putida move with alternating runs and tumbles that occur with a mean tumble rate. In the presence of gradients of a chemoattractant, they both perform chemotaxis. We set up a random-walk model that describes runs and tumbles as a stochastic process of the bacterium’s swimming direction and speed. The dynamics include rotational Brownian motion and shot noise for the swimming direction to initiate tumbling, while thermal and shot noise together with a mean reverting drift-term analogously to an Ornstein-Uhlenbeck process governs the speed dynamics. In order to infer the parameters of our model, generalized Kramers-Moyal coefficients are calculated for our model and matched to the ones determined from experimental trajectories. In contrast to common tumbling recognition algorithms no free parameters need to be preset. We first show that our method identifies the classical bacterial chemotaxis strategy of E. coli and P. putida, i.e., the tumble rate decreases along the chemical gradient. We also find evidence that a subpopulation of E. coli reduces its mean tumble angle when swimming in this direction.