Characterization of a marine endolysin LysVPB against Vibrio parahaemolyticus

Currently, there is an urgent to develop safe and environmentally friendly alternatives to antibiotics for combating Vibrio parahaemolyticus. Endolysins are considered promising antibacterial agents due to their desirable range of action and ability to deal with antibiotic-resistant bacteria. While numerous Vibrio phages have been identified, the research on their endolysins is still in its infancy. In this study, a novel endolysin called LysVPB was cloned and expressed in Pichia pastoris. Phylogenetic analysis revealed that LysVPB bears little resemblance to other known endolysins, highlighting its unique nature. Homology modeling identified a putative calcium-binding site in LysVPB. The recombinant LysVPB achieved a lytic activity of 64.8 U/mL and had a molecular weight of approximately 17 kDa. LysVPB exhibited enhanced efficacy at pH 9.0, with 60 % of its maximum activity observed within the broad pH range of 6.0-10.0. The catalytic efficiency of LysVPB peaked at 30 °C but significantly declined beyond 50 °C. Ba²⁺, Co²⁺, and Cu²⁺ showed inhibitory effects on the activity of LysVPB, while Ca²⁺ can boost it to 126.8 %. Furthermore, LysVPB exhibited satisfactory efficacy against strains of V. parahaemolyticus. LysVPB is an innovative phage lysin with good characteristics that are specific to certain hosts. The modular nature of LysVPB allows for efficient domain exchange with alternative lysins as antimicrobial components and fusion with antimicrobial peptides. This opens up possibilities for engineering chimeric lysins in a broader range of target hosts with high antimicrobial effectiveness and strong activity under physiological conditions.