Engineering Cooperation in an Anaerobic Coculture

Area of Science:

• Microbiology
• Synthetic Biology
• Microbial Ecology

Background:

• Most microbes interact in multispecies communities, yet pure culture studies dominate research.
• Understanding the emergence and mechanisms of microbial cooperation is limited.
• Studying microbial interactions in controlled laboratory settings is essential.

Purpose of the Study:

• To engineer and study the emergence of cooperation between Shewanella oneidensis and Geobacter sulfurreducens.
• To establish both commensal and obligate mutualistic bacterial cocultures.
• To investigate the metabolic strategies driving cooperation in bacterial communities.

Main Methods:

• Engineered a commensal coculture using a glycerol utilization plasmid (pGUT2) in S. oneidensis.
• Created an obligate mutualism by deleting the fumarate reductase gene in S. oneidensis.
• Analyzed metabolic shifts, including glycerol and malate metabolism, and gene deletions.

Main Results:

• Established a cross-feeding commensal coculture where S. oneidensis provided acetate to G. sulfurreducens.
• Developed an obligate mutualism where both species depended on each other for growth.
• Observed a metabolic strategy shift from glycerol catabolism to malate metabolism in the obligate mutualism.

Conclusions:

• The engineered coculture system serves as a model for studying cooperation emergence in bacteria.
• Genetic modifications can drive the transition from commensalism to obligate mutualism.
• Metabolic flexibility and adaptation are key factors in shaping microbial interactions and community structure.