The effect of antibacterial peptide ε-Polylysine against Pseudomonas aeruginosa biofilm in marine environment

Natural agents with antimicrobial properties have a broad potential to resist biofilm adhesion in marine environments. ε-Polylysine (E-PL) is a natural cationic, homomeric polymer with 25–30 lysine residues that can resist microbial biofilm adhesion due to its stability, nontoxicity, and biodegradability. The current study investigated the action of E-PL against Pseudomonas aeruginosa biofilm isolated from a marine environment. Crystal violet staining was used to examine the effects of E-PL on the formation and destruction of mature biofilms. Scanning Electron and fluorescence microscopy revealed that E-PL treatment damaged the biofilm structure and affected the secretion of extracellular polymers. The CCK8 colorimetric assay showed that E-PL also decreased the metabolic activity and motility of biofilm bacteria. QPCR and transcriptome analysis revealed that E-PL affected biofilm formation and transcriptional regulation by downregulating genes involved in flagellar synthesis (flgE, PA4651, pilW), chemotaxis transduction (PA1251, PA4951, PA4788), biofilm biosynthesis (pelC, pelD, pslK, plsM), transcriptional regulation (PA3973, PA3508, PA0268), phenazine biosynthesis (phzM, phzH, phzS), and electron transfer (PA5401, PA5400, PA3492). This study used multiple methods to identify the mechanism of E-PL action against biofilm, informing the design of novel biofilm treatment methods.