Bacteria-phage (co)evolution is constrained in a synthetic community across multiple bacteria-phage pairs

Area of Science:

• Microbial Ecology
• Evolutionary Biology
• Genomics

Background:

• Bacteriophages (phages) are key regulators of bacterial populations, influencing microbial community structure and function.
• Eco-evolutionary dynamics between bacteria and phages are shaped by reciprocal evolution, with bacteria developing resistance and phages evolving infectivity.
• Previous research primarily used isolated bacteria-phage pairs, limiting understanding of natural, multi-species interactions.

Purpose of the Study:

• To investigate the impact of coevolutionary dynamics on bacteria-phage interactions within a mixed-species soil microbial community.
• To compare eco-evolutionary outcomes in isolated pairs versus a polyculture system.

Main Methods:

• Experimental evolution over 8 weeks using three soil bacteria (Ochrobactrum sp., Pseudomonas sp., Variovorax sp.) and three species-specific bacteriophages.
• Comparison of host-parasite dynamics in isolated pairs versus a mixed bacterial-phage community (polyculture).

Main Results:

• Phage resistance evolution was significantly inhibited in polyculture compared to isolated pairs, particularly for Ochrobactrum.
• Substantial variation was observed in phage effects on bacterial densities and coevolutionary trajectories among different bacteria-phage pairs.
• Bacteria demonstrated a relative advantage in polyculture, evidenced by higher phage extinction rates and/or lower phage densities.

Conclusions:

• Findings highlight the challenges in generalizing monoculture results to complex polyculture systems.
• The study underscores the importance of considering multi-species interactions for a comprehensive understanding of microbial eco-evolutionary dynamics.
• Results suggest bacteria may possess inherent advantages over phages in natural, competitive environments.