Destabilization of a flow focused suspension of magnetotactic bacteria

TL;DR

This paper investigates how magnetotactic bacteria suspended in flow exhibit complex behaviors, including jetting and a novel pearling instability, revealing new structuring phenomena in driven active matter systems.

Contribution

It introduces a new experimental system for studying magnetotactic bacteria under flow and magnetic stimuli, highlighting the destabilization and structuring capabilities of driven active matter.

Findings

Magnetic field and flow induce jetting in bacteria suspension.

A new pearling instability is observed under competing stimuli.

The study demonstrates complex structuring in driven active matter.

Abstract

Active matter is a new class of material, intrinsically out-of equilibrium with intriguing properties. So far, the recent upsurge of studies has mostly focused on the spontaneous behavior of these systems --in the absence of external constraints or driving--. Yet, many real life systems evolve under constraints, being both submitted to flow and various taxis. In the present work, we demonstrate a new experimental system which opens up the way for quantitative investigations, and discriminating examinations, of the challenging theoretical description of such systems. We explore the behavior of magnetotactic bacteria as a particularly rich and versatile class of driven matter, which behavior can be studied under contrasting and contradicting stimuli. In particular we demonstrate that the competing driving of an orienting magnetic field and hydrodynamic flow lead not only to jetting, but also unveils a new pearling instability. This illustrates new structuring capabilities of driven active matter.