Phage vB_KpnS_MK54: lPS-associated factors involved in phage adsorption and depolymerase-driven anti-biofilm effects

Understanding phage K. pneumoniae-host interactions is essential for elucidating phage infection mechanisms and developing phage-derived antibacterial strategies. This showed that lipopolysaccharide (LPS) plays an important role in phage vB_KpnS_MK54 adsorption by constructing the isogenic deletion mutants LPKPΔmsbA and LPKPΔlpxB, in which phage adsorption was reduced by 2-3 log compared with the wild-type strain. Biofilms are associated with persistent infections and increased tolerance to antimicrobial treatment, posing a significant clinical challenge. We further characterized the recombinant depolymerase Dep_Zy, which exhibited potent depolymerase and antibiofilm activities, including depolymerase activity at 0.1 μg/mL, 55% inhibition of biofilm formation at 10 μg/mL, and 30% degradation of mature biofilms at 1 μg/mL. Notably, Dep_Zy potentiated the activity of conventional antibiotics, resulting in a 1-3 log reduction in biofilm-associated bacterial counts when combined with kanamycin, gentamicin, or streptomycin. These findings elucidate the molecular basis of phage-host interactions and highlight Dep_Zy as a promising enzymatic strategy for controlling multidrug-resistant Klebsiella pneumoniae through biofilm disruption and antibiotic potentiation.