Guided run-and-tumble active particles: wall accumulation and preferential deposition.

Area of Science:

• Physics of active matter
• Microbiology
• Biophysics

Background:

• Bacterial biofilms represent a significant challenge across health, medical, and industrial sectors.
• Early biofilm development involves cell accumulation and deposition from planktonic states, influenced by motion and taxis.

Purpose of the Study:

• To derive analytical expressions for bacterial suspension properties (density, orientation, deposition rates).
• To investigate the impact of external guiding or taxis fields on these properties.
• To model variations in bacterial run-time strategies and their effect on deposition.

Main Methods:

• Derivation of analytical expressions for density, angular distributions, mean orientation, and deposition rates.
• Verification through simulations of confined active particles using run-and-tumble statistics.
• Modeling cell running behavior by varying run-time distributions (exponential to heavy-tailed).
• Incorporation of a preferential sticking probability model for deposition.

Main Results:

• Deposition rates are significantly affected by guiding torque but less so by changes in cell running behavior.
• Both guiding fields and altered running behavior impact the pair correlation function of deposited structures.
• Asymmetrical rotational drift of planktonic cells under a guiding field influences deposited biomass architecture.

Conclusions:

• Guiding fields are a major factor in controlling bacterial deposition rates and biofilm structure.
• Bacterial rotational drift is a key physical mechanism driving organization in confined active particle suspensions.
• Understanding these physical mechanisms can inform strategies to manage or prevent biofilm formation.