Regensburg 2016 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 16: Microswimmers I (joint session DY/BP)

DY 16.9: Vortrag

Dienstag, 8. März 2016, 12:00–12:15, H47

Tumbling of an E. coli: role of rotation-induced polymorphism and external shear — •Tapan Chandra Adhyapak and Holger Stark — Institut für Theoretische Physik, Technische Universität Berlin, D - 10623 Berlin, Germany

Many multiflagellated bacteria such as E. coli adopt a run-and-tumble strategy to detect and direct themselves in chemical gradients in their surroundings. Tumbles are events which mark nearly abrupt changes in the direction of straight runs of the bacterium. Reversal of rotation of one or more of the flagella, which under normal rotation act as the propelling part of the bacterium, initiates these tumbles. Simultaneously, flagella that are reverse rotated are observed to undergo a series of polymorphic transitions between different flagellar states [1].

To understand the need, if there is any, of these transitions for an effective tumbling event has remained a long-standing problem. We present here a detailed numerical investigation unraveling the correlation between flagellar conformational changes and an efficient tumbling strategy for E. coli. Importance of these transitions in comparison to the contribution from hydrodynamic and steric interactions [2] will be addressed. At the end the nature of a tumbling event in sheared environment will also be discussed.

[1] R. Vogel and H. Stark, Phys. Rev. Lett. 110, 158104 (2013).

[2] T.C. Adhyapak and H. Stark, Phys. Rev. E 92, 052701 (2015).