Isolation and characterization of Salmonella Typhimurium monophasic variant phage and its application in foods

Salmonella Typhimurium monophasic variant (STm) is an emerging Salmonella serotype that causes food poisoning through the contamination of various foods, including animal products, vegetables, and fruits. In particular, the increasing prevalence of multidrug-resistant STm highlights the urgent need to develop effective strategies to control this pathogen. In this work, a novel and broad-spectrum Salmonella phage named vB_Sal_TmvP009 was isolated and characterized. Morphological and genomic analyses revealed that phage vB_Sal_TmvP009 belonged to the genus Jerseyvirus. Phage vB_Sal_TmvP009 was tolerant to a wide range of temperatures (-20°C∼60°C) and pH values (3∼12). The optimal multiplicity of phage infection was 0.0001, and it had a shorter latent period (8 min), longer lysis period (70 min), and a burst size of 292 PFU/cell. A total of 13 Salmonella serotypes could be lysed by phage vB_Sal_TmvP009. Furthermore, phage vB_Sal_TmvP009 inhibited the growth of multidrug-resistant Salmonella in lettuce or milk with the highest suppression of 3.4 and 3.7 log CFU/mL within 24 h, respectively. The genome of phage vB_Sal_TmvP009 contains lysin and spanin protein, but no tRNA, virulence factors, or drug resistance-related genes. These findings suggest that phage vB_Sal_TmvP009 is a promising antibacterial agent for controlling Salmonella in the food industry.