Discovery of phage lysin against Vibrio parahaemolyticus and characterization of its antibacterial activity

Vibrio parahaemolyticus, a major seafood-borne pathogen, causes human gastroenteritis and significant aquaculture economic losses. While bacteriophage lysins show promise against bacterial pathogens, their effectiveness against Gram-negative species remains limited by outer membrane impermeability. Through computational analysis, we identified 893 Vibrio-targeting lysins and selected 25 representatives using sequence similarity networks and biochemical parameters. Ten novel lysins, including LysV569, were successfully expressed and 5 of them were able to reduce V. parahaemolyticus ATCC 17802 by more than 2 log₁₀ CFU/mL without outer membrane permeabilizers. LysV569 demonstrated dose- and time-dependent bactericidal activity against V. parahaemolyticus ATCC 17802. Impressively, after pre-incubation for 30 min over a wide temperature range (4 °C to 85 °C), it retained >99% of its activity, demonstrating exceptional thermostability. At 100 μg/mL, LysV569 removed 96.6% of existing biofilms (with EDTA), inhibited >95% new biofilm formation within 24 h (without EDTA) and reduced bacterial load by 2-3 log₁₀ CFU/mL on salmon and food-contact surfaces. This work identified a promising candidate for the control of V. parahaemolyticus in food and environmental settings.