A multiphase theory for spreading microbial swarms and films

Area of Science:

• Microbiology
• Biophysics
• Fluid Dynamics

Background:

• Bacterial swarming and biofilm formation are key multicellular processes for microbial colonization.
• Fluid uptake and transport significantly influence the morphology and spreading dynamics of these communities.
• Understanding these phenomena is crucial for controlling microbial growth in various environments.

Purpose of the Study:

• To develop a unified mathematical model for bacterial swarming and biofilm expansion.
• To investigate the roles of fluid flow, nutrient transport, and extracellular matrix swelling in microbial surface translocation.
• To explain experimental observations of microbial community expansion.

Main Methods:

• Development of a generalized two-phase thin-film model.
• Coupling of bacterial growth, extracellular matrix swelling, fluid flow, and nutrient transport.
• Analysis of steady-state and transient solutions under different nutrient and physical conditions.

Main Results:

• Swarm expansion is characterized by steady-state solutions in nutrient-rich, capillarity-dominated conditions.
• Biofilm growth is described by transient solutions limited by nutrient scarcity and polymer stress.
• The model successfully explains diverse experimental observations of microbial expansion.

Conclusions:

• Fluid dynamics and nutrient transport are critical physical constraints on microbial community organization.
• A unified physical framework can describe both bacterial swarming and biofilm formation.
• The model provides insights into the fundamental mechanisms driving microbial surface translocation.