Spatial structure favors microbial coexistence except when slower mediator diffusion weakens interactions.

Area of Science:

• Microbial Ecology
• Theoretical Ecology
• Biophysics

Background:

• Microbial communities often inhabit spatially structured environments.
• Interactions within these communities are frequently mediated by diffusible metabolites.

Purpose of the Study:

• To investigate how spatial structure and metabolite diffusion influence microbial coexistence.
• To model the spatial reorganization and selection of microbial species during enrichment.

Main Methods:

• Utilized a model incorporating explicit spatial distributions of microbial species.
• Simulated the enrichment process to observe spatial reorganization and species coexistence.
• Analyzed the impact of cell motility, mediator production/consumption, and diffusion rates.

Main Results:

• Slower cell motility enhances coexistence by facilitating co-localization with facilitators and avoidance of inhibitors.
• Spatial structure is more critical for coexistence in primarily facilitative interactions compared to competitive ones.
• Optimal coexistence is linked to moderate mediator production and consumption, with balanced rates.
• Slow mediator diffusion was found to disfavor coexistence due to weakened interaction strengths.

Conclusions:

• Cell motility, mediator dynamics, and spatial structure are key determinants of microbial coexistence.
• The interplay between production, consumption, motility, and diffusion shapes microbial community assembly in situ.
• Spatial structuring can be a powerful factor in maintaining microbial diversity under specific interaction conditions.