C-terminal cationic peptide modification enhances the anti-Vibrio parahaemolyticus activity of endolysin Lys53: Membrane disruption and applications in seafood safety.

چکیده اصلی

Endolysin is an enzyme produced by bacteriophages during the lysis cycle, capable of specifically degrading peptidoglycan in the bacterial cell wall. However, its application against gram-negative bacteria is limited by the outer membrane (OM) barrier, which prevents access to the cell wall. In this study, the endolysin Lys53 from the phage vB_VpaS_1601 was modified by fusing cationic peptides to obtain the engineered protein Lys53-C5aa. Lys53-C5aa significantly reduced Vibrio parahaemolyticus by 3.51 log CFU/mL at a concentration of 6.4 μM within 30 min and exhibited a wider lysis spectrum. Lys53-C5aa exhibited optimal lytic activity within a temperature range of 4 to 65 °C and a pH range of 5 to 10. Lys53-C5aa significantly enhanced OM permeability of V. parahaemolyticus and led to the leakage of intracellular nucleic acids, reaching 110.5 ng/μL at 75 min. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that Lys53-C5aa disrupted the structural integrity of V. parahaemolyticus. Lys53-C5aa also showed removal (41.83%) and inhibition (61.01%) effects on the biofilm of V. parahaemolyticus. Lys53-C5aa reduced V. parahaemolyticus counts in oysters by 2.14 and 2.40 log CFU/g at 4 °C and 25 °C, respectively, while causing reductions of 2.21 and 2.69 log CFU/g in Pacific white shrimp under the same conditions. These findings indicate that Lys53-C5aa represents a highly promising candidate for controlling V. parahaemolyticus contamination in aquatic products.

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