KP-C01: A Novel Phage with Tail-Associated Depolymerase Activity Against KL102 Carbapenem-Resistant <i>Klebsiella pneumoniae</i>

Background: The emergence and spread of carbapenem-resistant Klebsiella pneumoniae (CRKP) represent a major threat to global public health, necessitating effective therapeutic strategies to prevent infection. Materials and Methods: A novel bacteriophage, φKP-C01, was isolated and characterized using ST307 KL102 CRKP as the host. Results: One-step growth curve analysis and complete genome sequencing demonstrated φKP-C01 to be a highly efficient lytic phage. The absence of genes encoding virulence factors, drug resistance determinants, or lysogeny-related functions indicated its potential safety for therapeutic applications. Bioinformatic analysis identified orf5 as encoding Depo-C01, a putative tail fiber protein with predicted depolymerase activity. To validate this function, orf5 was cloned, and recombinant Depo-C01 was expressed and purified. Depolymerase activity specifically targeting the KL102 capsular polysaccharide of the CRKP host was confirmed via spot assay and transmission electron microscopy. Conclusion: Lytic phage φKP-C01 and its depolymerase Depo-C01 show strong potential for phage-based or enzymatic strategies targeting CRKP infections.