Characterization of vB_SaRS_FS19-1, a newly isolated broad-host-range and virulent bacteriophage infecting Staphylococcus aureus and its application in foods.

The bacteriophage vB_SaRS_FS19-1, isolated from urban sewage, produced numerous clear plaques, about 1 to 2 mm in diameter, on the S. aureus JP19 bacterial lawn. A broad host range of the bacteriophage vB_SaRS_FS19-1 was found, and the lysis rate of S. aureus was 84 % (42/50). Electron microscopic and genomic DNA analyses suggested that phage vB_SaRS_FS19-1 is a recently discovered absence of lysogeny genes phage, classified under the genus Kayvirus within the family Herelleviridae. Analyses of phylogeny and genomics indicated that there is a relatively close evolutionary relationship with Staphylococcus phage. Notably, phage vB_SaRS_FS19-1 demonstrated robust stability under diverse environmental conditions and showed stable lytic activity across a wide range of pH values (4-10) and temperatures (20-50 °C), even in a 3 M NaCl solution. Moreover, phage vB_SaRS_FS19-1 has the ability to inhibit and kill S. aureus JP19 in a dose-dependent manner in TSB. S. aureus JP19 in contaminated sausages and milk was successfully inhibited at phage MOIs of 100, 1 and 0.01 (P < 0.01). These results indicate that the lytic phage vB_SaRS_FS19-1 could be a promising candidate for managing S. aureus contamination in food products.