Identification of KL29 Type Acinetobacter baumannii phage of Obolenskvirus subfamily and Tail-Associated depolymerase activity

The emergence of multidrug-resistant Acinetobacter baumannii (MDR-AB) as a critical nosocomial pathogen, driven by its remarkable capacity for acquired antibiotic resistance and clonal dissemination, underscores an urgent need for novel therapeutic interventions. This study characterizes a novel depolymerase derived from bacteriophage vB_AbaM_IME284, previously isolated against Ab333. Genomic analysis revealed taxonomic classification within the Caudoviricetes class and Obolenskvirus subfamily. Notably, plaque halo formation indicated polysaccharide depolymerase activity, prompting functional investigation of ORF49-encoded protein (designated Dp49). Recombinant Dp49 exhibited both depolymerase and antibacterial activities, demonstrating efficacy in biofilm inhibition and eradication. Furthermore, synergistic bactericidal effects were observed when combining Dp49 with human serum components (6-log reduction in viable counts). These findings position Dp49 as a promising therapeutic candidate for combating biofilm-associated MDR-AB infections.