Development of cationic peptide chimeric lysins based on phage lysin Lysqdvp001 and their antibacterial effects against Vibrio parahaemolyticus: A preliminary study

Cationic peptide chimeric lysins, Lysqdvp001-5aa, Lysqdvp001-10aa and Lysqdvp001-15aa, were designed based on lysin Lysqdvp001 from Vibrio parahaemolyticus ( V. parahaemolyticus ) phage qdvp001. These chimeric lysins showed equivalent peptidoglycan hydrolysis activities with Lysqdvp001 and could lyse the bacteria from the outside. The antibacterial activity as well as outer and inner membrane permeabilization of Lysqdvp001 and chimeric lysins against V. parahaemolyticus were Lysqdvp001-15aa>Lysqdvp001-10aa>Lysqdvp001-5aa>Lysqdvp001. Lysqdvp001-15aa exhibited an excellent antibacterial activity with minimum inhibition and bactericidal concentrations (MIC and MBC) of 0.2 and 0.4 mg/mL, respectively, and its antibacterial spectrum was much broader than phage qdvp001. Membrane hyperpolarization and membrane phospholipid exposure of V. parahaemolyticus were observed after Lysqdvp001-15aa treatments. Transmission electron microscope (TEM) showed Lysqdvp001-15aa destroyed structure integrity of V. parahaemolyticus . Besides, MIC and MBC of Lysqdvp001-15aa decreased V. parahaemolyticus counts in oyster by 3.20 and 4.03 log 10 CFU/g. Lysqdvp001-15aa at MBC eradicated about 50% of V. parahaemolyticus biofilms and inhibited over 90% of the formation of the bacterial biofilms.