Adaptive evolution of pseudomonas aeruginosa during long-term co-culture with macrophages

• Main Author: Ding, Yichen
• Other Authors: Yang Liang
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Science::Biological sciences::Microbiology::Bacteria
• Online Access: http://hdl.handle.net/10356/53819
• Institution: Nanyang Technological University

Adaptive evolution of bacterial pathogens to the host environment is critical for their success during long-term infections. Previous studies have shown that adaptation of Pseudomonas aeruginosa did occur during chronic infections, which is probably driven by physical conditions, and the host immune system. Although various models have been developed to gain insight into the evolution of bacterial pathogens in host environment, there is no current model to study if the evolution of bacterial pathogens can be driven by phagocytes in vitro. In this study, we co-cultured wildtype P. aeruginosa with macrophages for 28 days under experimental conditions, and have identified two groups of mutants in replicate co-culture populations, namely Autolytic lasR mutant, and mutants with rough colonies and enhanced biofilm formation. The presence of both mutants in multiple co-culture populations suggested parallel evolution of P. aeruginosa towards those two phenotypes. Our data demonstrated that during in vitro co-culture, macrophages indeed drove the evolution of P. aeruginosa. In agreement with clinical studies where both of the two mutants were found in Cystic Fibrosis airways, our results also suggested that evolution of both mutants in vivo during chronic infection might be driven by phagocytes from host immune system.