Confinement and activity regulate bacterial motion in porous media

Area of Science:

• Microbiology
• Biophysics
• Environmental Science

Background:

• Bacterial motility is crucial for various applications, including healthcare and environmental remediation.
• Escherichia coli (E. coli) typically uses run-and-tumble dynamics in homogeneous environments.
• Confined E. coli in porous media displays distinct hopping-and-trapping motility.

Purpose of the Study:

• To investigate the mechanisms governing bacterial hopping-and-trapping motility in porous media.
• To determine the influence of pore-scale confinement and cellular activity on bacterial movement.
• To validate predictions from an entropic trapping model.

Main Methods:

• Direct visualization techniques were employed to observe bacterial behavior.
• Experiments were conducted in disordered porous media with varying pore sizes.
• Cellular activity was modulated to assess its impact on motility patterns.

Main Results:

• Bacterial hopping is primarily dictated by pore-scale confinement and is independent of cellular activity.
• Bacterial trapping is influenced by the interplay between pore-scale confinement and cellular activity.
• Experimental findings align with predictions from the entropic trapping model.

Conclusions:

• Bacterial motility in porous media is regulated by a combination of physical confinement and cellular activity.
• Hopping-and-trapping motility provides new insights into microbial transport in heterogeneous environments.
• This research can inform the development of predictive models for bacterial behavior in complex settings.