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Published on: May 23, 2020
Social cheating in Pseudomonas aeruginosa quorum sensing
Kelsi M Sandoz1, Shelby M Mitzimberg, Martin Schuster
1Department of Biomedical Sciences and Microbiology, Oregon State University, Corvallis, OR 97331, USA.
Summary
Bacterial quorum sensing (QS) mutants emerge as "social cheaters," exploiting group benefits. This suggests QS disruption strategies may be effective against Pseudomonas aeruginosa infections.
Area of Science:
- Microbiology
- Bacterial communication
- Pathogen virulence
Background:
- Quorum sensing (QS) coordinates gene expression in bacteria like Pseudomonas aeruginosa, controlling virulence factors.
- QS-deficient mutants, often with lasR mutations, are frequently found in P. aeruginosa infections.
- The emergence mechanism of these QS-deficient variants remains unclear.
Purpose of the Study:
- To investigate the emergence mechanism of lasR mutants in Pseudomonas aeruginosa.
- To determine if lasR mutants act as social cheaters, benefiting from QS-controlled factors produced by wild-type bacteria.
- To understand the implications of lasR mutant emergence for bacterial population dynamics and antivirulence strategies.
Main Methods:
- In vitro evolution of P. aeruginosa wild-type strain for approximately 100 generations under growth-promoting QS conditions.
- Detection and characterization of emerging lasR mutant subpopulations.
- Coculture experiments comparing the growth of lasR mutants with the wild-type strain.
- Analysis of quorum-controlled gene expression during different growth phases.
Main Results:
- An emerging subpopulation of lasR mutants was detected after prolonged in vitro evolution.
- lasR mutants exhibited a growth advantage when cocultured with the wild-type P. aeruginosa strain.
- Quorum-controlled genes showed high early expression, indicating a metabolic burden associated with QS during growth.
- The emergence of QS-deficient variants indicates high QS activity in the population, not insignificance.
Conclusions:
- lasR mutants function as social cheaters, ceasing QS factor production and exploiting group benefits.
- The metabolic burden of QS during growth favors the emergence of QS-deficient mutants.
- The presence of QS-deficient variants signals high QS activity and suggests potential efficacy of QS-disrupting antivirulence therapies.
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