Development of the phage lysin-loaded liposomes as preservatives for live clams

Exogenous applications of phage lysins against Vibrio parahaemolyticus ( V. parahaemolyticus ) are a challenge due to the gram-negative bacteria outer membrane barrier. This study aimed to improve the antibacterial effect of V. parahaemolyticus phage lysin Lysqdvp001 (Lys), the best-characterized lysin with lytic activity against multiple species of Vibrio s, by using liposome delivery. Various kinds of Lys-loaded liposome (Lys-lip) systems were designed and tested. The antibacterial activities of cationic guar gum (CGG) containing liposomes were much higher than the other liposomes, causing >5 log 10 CFU/mL of reductions of V. parahaemolyticus in buffer and severely damaging the bacterial cell structure. Moreover, some CGG liposome formulations retained high antibacterial effect after both 60–80 °C heat treatments and freeze-drying. Besides, the most stable liposome formulation killed 99 % of V. parahaemolyticus in the seawater with live clams, and its depuration rate against the bacterial contaminated clams also reached 99 %.