Regensburg 2013 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 36: Statistical Physics in Biological Systems IV (joint with BP)
DY 36.7: Talk
Friday, March 15, 2013, 11:00–11:15, H44
Random walks of bacteria: How the motility pattern affects diffusion and chemotaxis — •Johannes Taktikos1,2, Holger Stark2, and Vasily Zaburdaev1 — 1Max-Planck-Institut für Physik komplexer Systeme, Dresden — 2Institut für Theoretische Physik, Technische Universität Berlin
The motility patterns of many bacterial species can be described with the help of random walk models. Swimming E. coli bacteria alternate almost straight runs with tumbling events, which randomize the direction of cell motion but keep a certain persistence. The majority of marine bacteria fully reverse their swimming direction after a tumbling event. However, the swimming strategy of the marine bacterium V. alginolyticus was recently discovered to consist of a strict sequence of reversal and completely randomizing flick events between the runs [Xie et al., PNAS 108, 2246 (2011)]. Remarkably, all these bacteria are capable to undergo chemotaxis – the ability to adjust their swimming direction to the concentration gradient of certain chemicals. We propose a generalized random walk model describing these motility patterns and use it to characterize the diffusion process of bacteria moving in chemically neutral environments. In the presence of a small gradient of a signaling chemical we calculate the chemotactic drift velocity along the gradient and analyze how it depends on the particular motility pattern. Our calculations show that the motility pattern alone cannot explain experimentally observed differences in the chemotactic behavior of E. coli and V. alginolyticus bacteria. This result suggests that the chemotactic internal response function of both bacteria differ.