Isolation and characterization of SGF3, a novel Microviridae phage infecting Shigella flexneri

In the context of widespread bacterial contamination and the endless emergence of antibiotic-resistant bacteria, more effective ways to control pathogen infection are urgently needed. Phages become potential bactericidal agents due to their bactericidal specificity and not easy resistance to bacteria. But an important factor limiting its development is the lack of phage species. Therefore, the isolation of more new phages and studying their biological and genomic characteristics is of great significance for subsequent applications. So, in this study, SGF3, a Microviridae phage, which has shown lytic activity against Shigella flexneri, was isolated, purified, and characterized. Morphological and phylogenetic analyses identified it as a phiX174 species belonging to the Microviridae family. The latent period of phage SGF3 was 20 min, with an average burst size of approximately 7.1. Host spectrum experiments indicated its strong host specificity. Furthermore, the biofilm removal efficiency was increased by 20%-25% when SGF3 was coupled with other phages. In conclusion, the phage SGF3 found in this study was a lytic phage belonging to the Microviral family, and could be added as an auxiliary material in the phage cocktail. Studies of its characteristics and bactericidal properties had enriched the germplasm resources of microphages, provided more potential material in fighting against emerging and existing multidrug-resistant bacteria.