Wall entrapment of peritrichous bacteria: a mesoscale hydrodynamics simulation study

Area of Science:

• Biophysics
• Fluid Dynamics
• Microbiology

Background:

• Microswimmers, like E. coli bacteria, display unique behaviors near surfaces.
• Understanding wall interactions is crucial for characterizing microbial dynamics.

Purpose of the Study:

• To investigate the entrapment process of E. coli-type cells at a no-slip wall.
• To elucidate the roles of hydrodynamic and steric interactions in cell-wall dynamics.

Main Methods:

• Mesoscale hydrodynamics simulations were employed.
• An E. coli-type cell was modeled as a spherocylindrical body with helical flagella.

Main Results:

• Three distinct entrapment stages were identified: approaching, scattering, and surface-swimming.
• Steric interactions were found to be dominant in the entrapment process.
• Hydrodynamic interactions modulated adsorption dynamics and induced circular motion near the wall.

Conclusions:

• Cell-wall interactions involve a interplay between steric and hydrodynamic forces.
• E. coli exhibits significant wobbling dynamics and wall-directed orientation during surface swimming.