Rheologically tuned diffusion modulates quorum sensing in Vibrio fischeri

TL;DR

This study investigates how fluid viscosity and rheology influence Vibrio fischeri's motility and quorum sensing, revealing that physical properties of the environment modulate bacterial communication and luminescence.

Contribution

It demonstrates how rheological properties of fluids affect bacterial movement and quorum sensing, providing new insights into microbial adaptation in complex habitats.

Findings

Higher viscosity increases slow, turning swimming modes in V. fischeri.

Luminescence varies with fluid rheology, peaking then decreasing in Newtonian fluids.

Cell exploration ability influences the timing and strength of bacterial communication.

Abstract

Understanding how the physical properties of a fluid influence bacterial behavior is essential for explaining how microorganisms interact with their environment and with animal hosts. Here, we examine how changes in fluid viscosity and rheological properties affect the locomotion of the marine bacterium Vibrio fischeri and its ability to produce luminescence through cell--cell communication. We track the three-dimensional motion of single cells in well-defined fluids with different physical properties and measure the luminescence emitted by cell populations. We find that fluids with higher viscosity cause V. fischeri to spend more time in a slower, turning-focused swimming mode, which reduces how effectively cells spread out and encounter the chemical signals required to activate luminescence. As a result, luminescence first increases and then decreases in Newtonian fluids, but decreases monotonically in fluids that exhibit non-Newtonian rheological behavior. Computer simulations based on our measurements confirm that the ability of cells to explore their surroundings plays a central role in determining when and how strongly they communicate. These findings reveal a direct link between the physical environment, bacterial movement, and collective behavior, and offer new insight into how microorganisms adapt to complex fluid habitats, including those found inside animal hosts.