Substrate geometry affects population dynamics in a bacterial biofilm

Area of Science:

• Microbiology
• Biophysics
• Evolutionary Biology

Background:

• Biofilms grow on diverse surfaces, including irregular ones like dental plaques and soil micropores.
• Most biofilm research uses flat surfaces, limiting understanding of how surface topography affects population dynamics.

Purpose of the Study:

• Investigate the influence of surface irregularities on biofilm population dynamics, genetic drift, and selection.
• Explore how surface topography can be leveraged to control microbial evolution.

Main Methods:

• Cultured *E. coli* biofilms in microwells with corrugated surfaces.
• Utilized a microscopically detailed computer model to simulate biofilm growth and mechanics.
• Experimentally tested antibiotic-sensitive and resistant mutants on corrugated surfaces with rifampicin.

Main Results:

• Corrugated surfaces induced stable, non-invading clonal sectors corresponding to surface features.
• Biofilm velocity fields and mechanical interactions (adhesion, friction) limited mixing and clonal expansion.
• Selection was significantly suppressed, even for mutants with growth advantages, contrasting with flat surface experiments.

Conclusions:

• Surface topography is a critical factor influencing biofilm population dynamics and microbial evolution.
• Understanding the physics of biofilm growth, including mechanical interactions, is key to controlling biofilm evolution.
• Patterned surfaces offer a novel strategy to manage biofilm development and microbial adaptation.