Genomic characterization of three novel Shiga toxin-producing Escherichia coli lytic phages.

Shiga toxin-producing Escherichia coli (STEC) are major foodborne pathogens. In response to the need for safe biocontrol strategies, lytic phages have emerged as promising tools for STEC control. This study analyses genomic features of three novel phages, L73, PG3 and A4.3, isolated from cattle farms using STEC strains as hosts. L73 and PG3 were classified as Tequatrovirus, while A4.3 as Vequintavirus. Genomic analyses revealed no markers of lysogeny, antimicrobial resistance, or virulence. Phylogenetic and comparative analyses confirmed close relationships to reference phages of each genus, while also revealing distinct genetic differences. These phages constitute genomically well-supported candidates for future evaluation as STEC biocontrol agents.