Directional Swimming of B. Subtilis Bacteria Near a Switchable Polar Surface

TL;DR

This study demonstrates that B. Subtilis bacteria can detect and respond to the polar order of a ferroelectric nematic liquid crystal surface, moving antiparallel to its polarization without immobilization, suggesting potential for directed bacterial control.

Contribution

It reveals that bacteria can sense and respond to the macroscopic polar order of a ferroelectric nematic liquid crystal surface through surface interactions, a novel insight into bacterial-surface interactions.

Findings

B. Subtilis moves antiparallel to NF surface polarization.

Bacterial speed remains unchanged with or without NF layer.

Bacteria do not become immobilized on ferroelectric surfaces.

Abstract

The dynamics of swimming bacteria depend on the properties of their habitat media. Recently it was shown that the motion of swimming bacteria dispersed directly in a non-toxic water-based lyotropic chromonic liquid crystal can be controlled by the director field of the liquid crystal. Here we investigate whether the macroscopic polar order of a ferroelectric nematic liquid crystal (NF) can be recognized by bacteria B. Subtilis swimming in a water dispersion adjacent to a glassy NF film by surface interactions alone. We show that B. Subtilis tends to move in the direction antiparallel to the spontaneous electric polarization at the NF surface. Their speed was found to be the same with or without a polar NF layer. In contrast to observation on crystal ferroelectric films, the bacteria do not get immobilized. These observations may offer a pathway to creation of polar microinserts to direct bacterial motion in-vivo.