Theoretical modelling of competitive microbial range expansion with heterogeneous mechanical interactions

Area of Science:

• Microbiology
• Theoretical Biology
• Biophysics

Background:

• Microbial range expansion experiments reveal complex links between population dynamics, structure formation, and evolution.
• Understanding these dynamics is crucial for predicting microbial community behavior.

Purpose of the Study:

• To develop a theoretical model investigating the interplay of growth statistics and mechanical interactions in microbial colonies.
• To analyze how division-driven pushing and cell swapping influence colony structure and evolutionary dynamics.
• To explore the impact of varying division times and mechanical interactions on competitive growth scenarios.

Main Methods:

• Development of a theoretical model for microbial population growth.
• Implementation of cell division-driven pushing and swapping mechanics.
• Simulation of competitive growth between strongly and weakly interacting microbial strains.
• Inclusion of mutating cells to study their influence on colony structure.

Main Results:

• Cell division-induced pushing significantly influences colony structure, more so than cell sorting to the perimeter.
• The relative strengths of mechanical interactions between strains critically affect the outgrowth patterns.
• Experimental patterns observed in Neisseria gonorrhoeae range expansion were reproduced by modeling mutant interactions.

Conclusions:

• Mechanical interactions, particularly cell division forces, are key drivers of pattern formation in microbial range expansions.
• The model accurately predicts colony structures based on the mechanical properties of interacting microbial strains.
• This work provides a framework for understanding evolutionary dynamics in microbial populations driven by mechanical forces.