Characterization of Klebsiella phages PMBT12, PMBT63, and PMBT64 with functional insights into a Hoc-like, mucin-interacting protein of phage PMBT63

Three novel Klebsiella phages, PMBT12, PMBT63, and PMBT64, were isolated and characterized. The phages revealed distinct morphologies, phylogenetic backgrounds, and a high degree of genomic divergence. PMBT12 and PMBT64 exhibited narrow host ranges, whereas PMBT63 demonstrated a broader host range across the tested Klebsiella strains with diverse sequence and capsule types. PMBT63 possesses a large genome that approaches the size of jumbo T4-like phages, encodes 16 tRNAs, and exhibits high thermal stability up to 70°C. A conserved Hoc-like protein in PMBT63 was identified and structurally characterized, showing a highly conserved genomic context across diverse Enterobacteriaceae phages. Computational analyses predicted putative mucin-binding sites within this protein, which was corroborated experimentally by enhanced phage retention on mucin-coated surfaces. IMPORTANCE These findings identify Klebsiella phage PMBT63 as a promising candidate for therapeutic applications. It also highlights the importance of characterizing phages for potential phage-mucin interactions, which may influence their persistence and function within the gastrointestinal tract.