Isolation and Characterization of Two Novel Lytic Bacteriophages against Salmonella typhimurium and Their Biocontrol Potential in Food Products

Foodborne pathogens, such as <i>Salmonella</i>, are major factors that pose significant threats to global food safety and public health. <i>Salmonella typhimurium</i> is a prominent serotype contributing to non-typhoidal salmonellosis, which is a prevalent foodborne illness affecting humans and animals. Bacteriophages are considered one of the most environmentally friendly biocontrol agents, particularly in the food industry, owing to their high specificity and high safety. However, the emergency of phage-resistant mutants limits the biocontrol effect of phage treatment, leading to the requirement for a high diversity of lytic phages. Therefore, the study isolated and characterized two novel lytic <i>Salmonella</i> bacteriophages (SPYS_1 and SPYS_2) targeting <i>S. typhimurium</i> ATCC14028 and evaluated their effectiveness in reducing the contamination rates for milk and chicken tenders. Morphological and genomic analyses indicated that <i>Salmonella</i> phages SPYS_1 and SPYS_2 are novel species classified under the <i>genus Skatevirus</i> and the <i>genus Berlinvirus</i>, respectively. Both phages exhibited high stability across a broad range of thermal and pH conditions. The one-step growth curve result suggested that both phages had a short adsorption time and a large burst size in a single lytic cycle. The phage SPYS_1 demonstrated a noteworthy inhibition effect on the growth of <i>S. typhimurium</i> ATCC14028 in milk, resulting in a ~2-log reduction within the 2 to 4 h range. Overall, both phages have shown significant potential for application in food safety in the future.