Pseudomonas aeruginosa Psl exopolysaccharide (None)

Psl is a key exopolysaccharide produced by *Pseudomonas aeruginosa*, a Gram-negative opportunistic pathogen known for its robust biofilm formation and resistance to antibiotics. Psl plays a central role in the initial attachment of bacterial cells to surfaces, cell-to-cell interactions, and the maintenance of mature biofilm structure. The repeating unit of Psl is a neutral, branched pentasaccharide composed primarily of D-mannose, D-glucose, and L-rhamnose. Biosynthesis of Psl is directed by the psl operon (pslA-O), which encodes at least 12 proteins involved in its assembly and export. Psl is essential for initial surface attachment during early biofilm development and provides structural stability to mature biofilms. It also interferes with complement deposition, inhibits neutrophil functions, and enhances intracellular survival within phagocytes. Production is stimulated by elevated levels of c-di-GMP, which creates a positive feedback loop. Certain bacteriophages specifically recognize Psl on the bacterial surface and can disrupt established biofilms.

Bacteriophages disrupt biofilms by targeting bacteria expressing Psl exopolysaccharide.