Curvature-guided motility of microalgae in geometric confinement

TL;DR

This study investigates how the geometry of confined habitats influences microalgae motility, revealing that wall curvature guides their navigation, supported by experiments, simulations, and theory.

Contribution

It introduces a quantitative model showing how wall curvature affects microalgae movement in confined spaces, a novel insight into microorganism behavior in complex habitats.

Findings

Cell proximity to boundaries scales linearly with wall curvature.

The asymmetric dumbbell model accurately predicts curvature-guided navigation.

Experimental and simulation results align with theoretical predictions.

Abstract

Microorganisms, such as bacteria and microalgae, often live in habitats consisting of a liquid phase and a plethora of interfaces. The precise ways in which these motile microbes behave in their confined environment remain unclear. Using experiments, Brownian dynamics simulations, and analytical theory, we study the motility of a single Chlamydomonas microalga in an isolated microhabitat with controlled geometric properties. We demonstrate how the geometry of the habitat controls the cell's navigation in confinement. The probability of finding the cell swimming near the boundary scales linearly with the wall curvature, as seen for both circular and elliptical chambers. The theory, utilizing an asymmetric dumbbell model of the cell and steric wall interactions, captures this curvature-guided navigation quantitatively with no free parameters.