Global dynamics of microbial communities emerge from local interaction rules

Area of Science:

• Microbiology
• Systems Biology
• Mathematical Biology

Background:

• Microbes often form structured communities like biofilms.
• Neighbor interactions via molecule exchange influence community properties (composition, arrangement, growth).
• Understanding these emergent properties requires linking molecular mechanisms to community-level outcomes.

Purpose of the Study:

• To develop a mathematical framework connecting molecular interactions to community-level properties.
• To investigate how local cell-cell interactions shape microbial community structure and function.
• To analyze the impact of spatial structure on mutualistic cross-feeding communities.

Main Methods:

• Developed a two-part mathematical framework: a biophysical model and a graph-based model.
• The biophysical model derives local interaction rules (range, strength) from molecular parameters.
• The graph-based model determines equilibrium community properties from interaction rules.

Main Results:

• Key molecular parameters (uptake, leakage rates) dictate community-level properties.
• Spatial structure can be detrimental to mutualistic cross-feeding microbial communities.
• The model qualitatively recapitulates experimental microbial community properties.

Conclusions:

• The framework links microscopic molecular interactions to macroscopic community behavior.
• It provides insights into how community properties emerge from cell-cell interactions.
• The model is applicable to diverse two-cell-type systems in biology.