Interaction-dependent effects of surface structure on microbial spatial self-organization.

Area of Science:

• Microbial Ecology
• Systems Biology
• Spatial Ecology

Background:

• Microbial communities exhibit spatial self-organization, impacting their function and evolution.
• The factors driving this spatial organization, particularly the role of physical structures, are not fully understood.

Purpose of the Study:

• To investigate how physical objects on a surface affect the spatial self-organization of microbial communities.
• To determine if the presence of physical objects alters the patterns and diversity of microbial range expansions.

Main Methods:

• Range expansion experiments were conducted using isogenic strains of *Pseudomonas stutzeri*.
• Experiments were performed both with and without physical objects present on the growth surface.
• Quantification of spatial self-organization, interspecific boundary densities, and diversity along the expansion frontier.

Main Results:

• Physical objects induced local deformities at the expansion frontier, which intensified over time.
• These deformities modulated interspecific boundary densities and diversity, with effects dependent on microbial interactions.
• Competitive interactions led to increased diversity and boundary density with physical objects, while cross-feeding interactions showed decreased diversity and boundary density.

Conclusions:

• Physical objects significantly impact microbial spatial self-organization by deforming expansion fronts.
• The effect of physical objects is contingent on the nature of microbial interactions (e.g., competition vs. cross-feeding).
• Predicting the influence of physical structures requires knowledge of community interactions and emergent spatial patterns.