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

Natural antibacterial agents with antimicrobial properties have a broad potential to prevent bacterial from forming biofilms adhesion in marine environments. ε-Polylysine (E-PL) consist of homomeric polymer with 25–30 lysine residues with stability, nontoxicity, and biodegradability. ε-Polylysine is a natural cationic antibacterial peptide that can resist microbial forming biofilm adhesion. 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.