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Issue 16, 2019
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3D dynamics of bacteria wall entrapment at a water–air interface

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Abstract

Swimming bacteria can be trapped for prolonged times at the surface of an impenetrable boundary. The subsequent surface confined motility is found to be very sensitive to the physico-chemical properties of the interfaces which determine the boundary conditions for the flow. The quantitative understanding of this complex dynamics requires detailed and systematic experimental data to validate theoretical models for both flagellar propulsion and interfacial dynamics. Using a combination of optical trapping and holographic imaging we study the 3D dynamics of wall entrapment of swimming bacteria that are sequentially released towards a surfactant-covered liquid–air interface. We find that an incompressible surfactant model for the interface quantitatively accounts for the observed normal and tangential speed of bacteria as they approach the boundary. Surprisingly we also find that, although bacteria circulate over the air phase in counterclockwise circular trajectories, typical of free-slip interfaces, the body axis is still tilted “nose down” as found for no-slip interfaces.

Graphical abstract: 3D dynamics of bacteria wall entrapment at a water–air interface

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Publication details

The article was received on 11 Jan 2019, accepted on 15 Mar 2019 and first published on 20 Mar 2019


Article type: Paper
DOI: 10.1039/C9SM00077A
Citation: Soft Matter, 2019,15, 3397-3406

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    3D dynamics of bacteria wall entrapment at a water–air interface

    S. Bianchi, F. Saglimbeni, G. Frangipane, D. Dell'Arciprete and R. Di Leonardo, Soft Matter, 2019, 15, 3397
    DOI: 10.1039/C9SM00077A

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