Regensburg 2016 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 53: Posters - Statistical Physics of Biological Systems
BP 53.3: Poster
Mittwoch, 9. März 2016, 17:00–19:00, Poster C
Inference of chemotactic strategies of E. coli and Pseudonomas putida using Kramers-Moyal coefficients — •Maximilian Seyrich1, Oliver Pohl1, Marius Hintsche2, 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 includes rotational Brownian motion and shot noise, which initiates tumbling events with rates based on chemical gradients.
By analyzing experimental data of swimming trajectories, we infer the parameters of our model. For this purpose generalized Kramers-Moyal coefficients are calculated of our shot-noise 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 for E. coli and P. putida, i.e., bacteria adapt their tumble rate to the chemical gradients. Second, we find evidence that a subpopulation of E. coli, unlike P. putida, uses an additional turning bias during tumble events. We provide statistics which distinguish tumble rate chemotaxis and angle bias chemotaxis using scaling arguments for the Kramers-Moyal coefficients.