Adaptive evolution of synthetic cooperating communities improves growth performance

Area of Science:

• Microbial Ecology and Evolution
• Synthetic Biology
• Systems Biology

Background:

• Symbiotic interactions are crucial for human health and biotechnology, with microbial mutualism being a widespread phenomenon in natural communities.
• Understanding the establishment, population dynamics, and evolutionary processes of cooperative interactions in microbial communities remains a significant challenge.

Purpose of the Study:

• To investigate the establishment and adaptive evolution of cooperative interactions in a synthetic bacterial community.
• To analyze the evolutionary trajectories and metabolic adaptations of bacterial auxotrophs engaged in mutualistic exchange.

Main Methods:

• Construction and adaptive evolution of a synthetic co-culture of leucine and lysine auxotrophic Escherichia coli.
• Measurement of co-culture growth rates and optical densities.
• Genome-scale metabolic modeling to simulate and analyze nutrient exchange dynamics.

Main Results:

• A viable co-culture was established and evolved to increase growth rates by approximately 3-fold.
• Independent evolutionary trajectories led to distinct community compositions, with genetic changes in both auxotrophs contributing to improved co-culture growth.
• Evolved isolates exhibited enhanced co-culture growth but reduced growth in monoculture, indicating a trade-off between cooperation and individual fitness.

Conclusions:

• Synthetic communities of auxotrophic bacteria can be established and adaptively evolved to enhance mutualistic interactions.
• Metabolic modeling accurately predicted experimental outcomes, underscoring the importance of nutrient exchange rates in community dynamics.
• The study provides insights into the evolutionary processes governing microbial cooperation and suggests exploring other interaction types.