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Issue 25, 2016
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Dynamics of a bacterial flagellum under reverse rotation

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To initiate tumbling of an E. coli, one of the helical flagella reverses its sense of rotation. It then transforms from its normal form first to the transient semicoiled state and subsequently to the curly-I state. The dynamics of polymorphism is effectively modeled by describing flagellar elasticity through an extended Kirchhoff free energy. However, the complete landscape of the free energy remains undetermined because the ground state energies of the polymorphic forms are not known. We investigate how variations in these ground state energies affect the dynamics of a reversely rotated flagellum of a swimming bacterium. We find that the flagellum exhibits a number of distinct dynamical states and comprehensively summarize them in a state diagram. As a result, we conclude that tuning the landscape of the extended Kirchhoff free energy alone cannot generate the intermediate full-length semicoiled state. However, our model suggests an ad hoc method to realize the sequence of polymorphic states as observed for a real bacterium. Since the elastic properties of bacterial flagella are similar, our findings can easily be extended to other peritrichous bacteria.

Graphical abstract: Dynamics of a bacterial flagellum under reverse rotation

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Publication details

The article was received on 20 Feb 2016, accepted on 23 May 2016 and first published on 24 May 2016

Article type: Paper
DOI: 10.1039/C6SM00443A
Citation: Soft Matter, 2016,12, 5621-5629

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    Dynamics of a bacterial flagellum under reverse rotation

    T. C. Adhyapak and H. Stark, Soft Matter, 2016, 12, 5621
    DOI: 10.1039/C6SM00443A

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