Wet-dry cycles protect surface-colonizing bacteria from major antibiotic classes.

Area of Science:

• Microbiology
• Environmental Science
• Antibiotic Resistance

Background:

• Antibiotic compounds are prevalent in microbial habitats with fluctuating hydration, such as soil and plant surfaces.
• These compounds mediate microbial competition, influencing community dynamics and evolution.
• The effect of wet-dry cycles on bacterial antibiotic response remains largely uninvestigated.

Purpose of the Study:

• To investigate the impact of recurrent wet-dry cycles on bacterial susceptibility to antibiotics.
• To elucidate the mechanisms by which wet-dry cycles confer protection against antibiotics.
• To explore the broader implications for microbial populations and antibiotic resistance.

Main Methods:

• Utilized Escherichia coli (E. coli) as a model organism.
• Employed a combination of experimental assays and computational modeling.
• Investigated bacterial responses under varying hydration states and salt concentrations.

Main Results:

• Wet-dry cycles were found to protect E. coli from beta-lactam antibiotics.
• Mechanisms of protection include tolerance induced by high salt concentrations and reduced cell growth during dry periods.
• A cross-protection effect was observed, where antibiotic exposure increased survival during subsequent dry phases.
• Similar protective effects were noted for other major antibiotic classes.

Conclusions:

• Recurrent wet-dry cycles represent a significant factor influencing bacterial survival and antibiotic efficacy in terrestrial environments.
• Understanding these hydration-driven protective mechanisms is crucial for predicting microbial population dynamics and the evolution of antibiotic resistance.
• Findings have broad implications for managing microbial communities and combating antibiotic resistance in natural and built environments.