Long-term Culturing of Pseudomonas aeruginosa in Static, Minimal Nutrient Medium Results in Increased Pyocyanin Production, Reduced Biofilm Production, and Loss of Motility

Pseudomonas aeruginosa is a multidrug-resistant opportunistic human pathogen that can survive in many natural and anthropogenic environments. It is a leading cause of morbidity in individuals with cystic fibrosis and is one of the most prevalent pathogens associated with nosocomial infections in the United States. It has been shown that this organism can survive and persist in low nutrient environments such as sink drains and inside the respiratory system of human hosts. How adaptation to these types of environments influences phenotypic traits of this organism has not been well studied. Here we implemented an experimental evolution system designed to imitate these environmental niches and identified phenotypic changes that occurred as a result of adaptation to such environments in six strains of P. aeruginosa with varying life history and colony phenotypes. We observed that adaptation to low nutrient environments resulted in decreased generation time, reduced cell size, reduced biofilm formation, increased pyocyanin production, and decreased motility. Our work is significant as it allows us to predict how this organism will evolve in hospital and domestic environments and can help us improve treatment options for patients.