Surface conversion of the dynamics of bacteria escaping chemorepellents

Braham, Asma; Lemelle, Laurence; Ducasse, Romain; Toukabri, Houyem; Mottin, Eleonore; Fabrèges, Benoit; Calvez, Vincent; Place, Christophe

doi:http://dx.doi.org/10.1140/epje/s10189-024-00450-7

Surface conversion of the dynamics of bacteria escaping chemorepellents

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Braham A, Lemelle L, Ducasse R, Toukabri H, Mottin E, Fabrèges B, et al. Surface conversion of the dynamics of bacteria escaping chemorepellents. Eur Phys J E Soft Matter. 2024 Sep 15;47(9):56. DOI: 10.1140/epje/s10189-024-00450-7

Abstract

Flagellar swimming hydrodynamics confers a recognized advantage for attachment on solid surfaces. Whether this motility further enables the following environmental cues was experimentally explored. Motile E. coli (OD ~ 0.1) in a 100 µm-thick channel were exposed to off-equilibrium gradients set by a chemorepellent Ni(NO3)2-source (250 mM). Single bacterial dynamics at the solid surface was analyzed by dark-field videomicroscopy at a fixed position. The number of bacteria indicated their congregation into a wave escaping from the repellent source. Besides the high velocity drift in the propagation direction within the wave, an unexpectedly high perpendicular component drift was also observed. Swimming hydrodynamics CW-bends the bacteria trajectories during their primo approach to the surface (< 2 µm), and a high enough tumbling frequency likely preserves a notable lateral drift. This comprehension substantiates a survival strategy tailored to toxic environments, which involves drifting along surfaces, promoting the inception of colonization at the most advantageous sites.