Characterization of endolysins from bacteriophage LPST10 and evaluation of their potential for controlling Salmonella Typhimurium on lettuce

Salmonella strains pose a great challenge to food safety. The exploration of bacteriophage endolysins can be a valuable measure for the prevention of Salmonella propagation in food, feed and agricultural products. The current study aims to obtain endolysins that efficiently lyse Salmonella Typhimurium (S. Typhimurium). Two possible endolysins LysWL59 and LysWL60 from bacteriophage LPST10 were identified, prepared, and characterized. Afterward, LysWL59 was utilized for the reduction of S. Typhimurium in Tris-HCl buffer or on lettuce. The results revealed that both LysWL59 and LysWL60 displayed broad lytic activity against chloroform treated Gram-negative bacteria. LysWL59 was more stable and remained active at pH ranging from 6.0 to 10.0, and at temperatures ranging from 4 to 90 °C. LysWL59, in combination with outer membrane permeabilizing agents, had the ability to reduce viable S. Typhimurium in Tris-HCl buffer or on lettuce, and 2.50 μmoL/L LysWL59 with 0.50 mmoL/L EDTA decreased S. Typhimurium by 93.03% within 1 h on lettuce. To the best of our knowledge, the activity of LysWL59 was superior to that of previously reported endolysins against Gram-negative strains, especially Salmonella. Therefore, LysWL59 represents a promising agent against Salmonella contamination. This study provides insights into the control of food pathogens by using endolysins.