Chapters authored
Role of Pyocyanin and Extracellular DNA in Facilitating Pseudomonas aeruginosa Biofilm Formation
Pseudomonas aeruginosa is an opportunistic Gram‐negative bacterium that is primarily responsible for infections related to cystic fibrosis (CF) airways, burn wounds, urinary tract infections, surgery‐associated infections, and HIV‐related illness. Pyocyanin and extracellular DNA (eDNA) are the major factors dictating the progression of biofilm formation and infection. Pyocyanin is a potent virulence factor causing cell death in infected CF patients and is associated with high mortality. eDNA is a key player in P. aeruginosa biofilm formation and is also responsible for the high viscosity of CF sputum that blocks the respiratory airway passages. In this chapter, we summarize our recent findings on the role of pyocyanin in facilitating P. aeruginosa biofilm formation. Pyocyanin promotes eDNA release in P. aeruginosa by inducing cell lysis mediated via hydrogen peroxide (H2O2) production. Pyocyanin intercalates with the nitrogenous bases of DNA and creates structural perturbation on the double‐helix structure. Pyocyanin‐eDNA binding significantly influences P. aeruginosa cell surface hydrophobicity and influences the physicochemical interactions facilitating bacterial cell‐to‐cell interaction (aggregation) and ultimately facilitates robust biofilm formation. A pyocyanin knockout (ΔphzA‐G) mutant is shown to have significantly reduced eDNA release and biofilm formation in comparison to its wild‐type. To this end, we discover that antioxidant glutathione directly binds to pyocyanin and modulates pyocyanin structure and function, thus inhibiting pyocyanin‐eDNA binding and consequently hampering biofilm development.
Part of the book: Microbial Biofilms