Characterization of Five Lytic Bacteriophages as New Members of the Genus Mosigvirus, Infecting Multidrug-Resistant Shiga Toxin-Producing Escherichia coli and Their Antibiofilm Activity

The emergence of multidrug-resistant Shiga toxin-producing <i>Escherichia coli</i> (STEC) poses a major challenge to public health and necessitates the development of alternative antimicrobial strategies. This study aimed to isolate and characterize five lytic bacteriophages belonging to the genus <i>Mosigvirus</i> and evaluate their potential as biocontrol against MDR STEC strains and their biofilms. The five bacteriophages, designated vB_EcoM-pJBB (ΦB), vB_EcoM-pJBC (ΦC), vB_EcoM-pJBJ (ΦJ), vB_EcoM-pJBK (ΦK), and vB_EcoM-pJBL (ΦL), were isolated from sewage treatment plant samples using STEC ATCC 43895 as host. Biological characterization included host range determination against 19 MDR STEC strains, one-step growth analysis, environmental stability assays, bacteriolytic activity assessment, and antibiofilm efficacy testing. Whole-genome sequencing and phylogenetic analyses were performed to determine genomic features and taxonomic classification. The phages demonstrated varying infectious capacities, lysing between six and 12 strains, with ΦL exhibiting the broadest spectrum of activity. All phages showed MOI-independent antibiofilm activity, preventing biofilm formation by approximately 70% and disrupting pre-formed biofilms by up to 80.3%. Genomic analysis revealed the absence of lysogeny markers, virulence factors, and antimicrobial resistance genes, while identifying putative depolymerase genes associated with tail fiber proteins. Phylogenetic analysis confirmed the taxonomic position of these phages within the <i>Mosigvirus</i> genus in the <i>Straboviridae</i> family. Our findings indicate that the newly identified <i>Mosigvirus</i> phages are promising candidates for phage-based biocontrol applications.