Bacteriostatic Activity of Vibrio parahaemolyticus Phage 460s1 and Its Endolysin

Vibrio parahaemolyticus is a common foodborne pathogen with drug-resistant strains now widespread. The use of phages to control resistant bacteria is a promising means of reducing public health pressure. In this study, V. parahaemolyticus phage 460s1 was isolated, which was active over a wide range of temperature (30-50°C) and pH (3-10). It exhibited a specific host range, lysing 16 of the 23 strains of V. parahaemolyticus. The phage 460s1 can effectively inhibit the growth of V. parahaemolyticus in shrimp at 15°C and 25°C, and bacterial count decreased by 3.46 log colony-forming unit/g at multiplicity of infection of 1000 at 24 h under 15°C. The phage 460s1 genome was sequenced, and it contains 105 open reading frames (ORFs), of which ORF 53 encodes putative endolysin. The ORF 53 protein was successfully expressed in Escherichia coli and reduced the optical density at 600 nm of host bacteria from 0.82 to 0.58 within 60 min at a concentration of 10 μmol/L. The endolysin also showed lytic activity against 20 strains of antimicrobial-resistant V. parahaemolyticus. Therefore, bacteriophage 460s1 and its endolysin are of great significance for the prevention and control of V. parahaemolyticus.