Active bacterial pattern formation in evaporating droplets

Fuente: arXiv
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Main Authors: Wilting, Twan J. S., Reijnier, Adriana W. B. P., Brebels, Michiel H. M., Villie, Alexandre, Colin, Remy, Gelderblom, Hanneke
Format: Preprint
Published: 2025
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author Wilting, Twan J. S.
Reijnier, Adriana W. B. P.
Brebels, Michiel H. M.
Villie, Alexandre
Colin, Remy
Gelderblom, Hanneke
author_facet Wilting, Twan J. S.
Reijnier, Adriana W. B. P.
Brebels, Michiel H. M.
Villie, Alexandre
Colin, Remy
Gelderblom, Hanneke
contents Bacteria living on surfaces are often confined to droplets. When these droplets evaporate, the motion of the liquid-air interface and the associated internal capillary flow confine the bacteria. Here we study how \emph{E. coli} bacteria interact with this capillary confinement and agglomerate at the droplet's contact line. We identify three different types of bacterial pattern formation that depend on the bacterial activity and the environmental conditions imposed by the evaporating droplet. When the evaporation is fast, the bacteria are slow or the suspension is dilute, a uniform contact-line deposit forms. However, when the capillary confinement concentrates the bacteria at the contact line beyond a critical number density, localized collective motion spontaneously emerges. In that case, the bacteria induce a local stirring of the liquid that allows them to self-organize into periodic patterns and enables them to collectively escape from the contact line. At very high number densities, these periodic patterns get destabilized by bacterial turbulence in the bulk of the droplet resulting in the formation of mobile bacterial plumes at the contact line. Our results show how the subtle interplay between the bacteria and the capillary flow inside the droplet that surrounds them governs their dispersal.
format Preprint
id arxiv_https___arxiv_org_abs_2511_09344
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Active bacterial pattern formation in evaporating droplets
Wilting, Twan J. S.
Reijnier, Adriana W. B. P.
Brebels, Michiel H. M.
Villie, Alexandre
Colin, Remy
Gelderblom, Hanneke
Fluid Dynamics
Soft Condensed Matter
Biological Physics
Bacteria living on surfaces are often confined to droplets. When these droplets evaporate, the motion of the liquid-air interface and the associated internal capillary flow confine the bacteria. Here we study how \emph{E. coli} bacteria interact with this capillary confinement and agglomerate at the droplet's contact line. We identify three different types of bacterial pattern formation that depend on the bacterial activity and the environmental conditions imposed by the evaporating droplet. When the evaporation is fast, the bacteria are slow or the suspension is dilute, a uniform contact-line deposit forms. However, when the capillary confinement concentrates the bacteria at the contact line beyond a critical number density, localized collective motion spontaneously emerges. In that case, the bacteria induce a local stirring of the liquid that allows them to self-organize into periodic patterns and enables them to collectively escape from the contact line. At very high number densities, these periodic patterns get destabilized by bacterial turbulence in the bulk of the droplet resulting in the formation of mobile bacterial plumes at the contact line. Our results show how the subtle interplay between the bacteria and the capillary flow inside the droplet that surrounds them governs their dispersal.
title Active bacterial pattern formation in evaporating droplets
topic Fluid Dynamics
Soft Condensed Matter
Biological Physics
url https://arxiv.org/abs/2511.09344