Characterization and therapeutic potential of newly isolated bacteriophages targeting the most common Salmonella serovars in Europe

Despite meticulous monitoring of Salmonella spp. throughout the food chain to ensure safer animal food products for consumers, the number of salmonellosis cases in humans continues to rise annually in Europe. Phage therapy emerges as a promising tool for controlling and eradicating Salmonella in primary production. This study aimed to fully characterize new phage therapy candidates isolated from animal sources. To achieve this, a phenotypic and genetic characterization of five phage isolates was conducted. The five phages demonstrated physical stability across a wide range of temperatures and pH levels, effectively lysing 12 different Salmonella serovars, including the most prevalent ones in the European Union in recent years, as well as multidrug-resistant strains isolated from the field. Additionally, four of the phages exhibited depolymerase production in the host range, with genomic analysis confirming that all five possessed sequences encoding for this activity, suggesting their potential as surface-disinfecting agents. Genetic analysis further revealed that the phages belong to distinct genera: Felixounavirus, Cornellvirus, Skatevirus, Agtevirus and Berlinvirus. Notably, none of the phages contained harmful sequences that could compromise their future application, such as virulence factors, antibiotic resistance genes or temperate markers. Overall, these five phages show promise as suitable candidates for phage therapy applications or phage-based Salmonella eradication strategies, where their integration in the existing biocontrol measures may enhance both food safety and public health.