A novel jumbo phage infecting Pseudomonas aeruginosa: genomic insights and phylogenetic classification.

Bacteriophages have re-emerged as therapeutic alternatives to antibiotics, and jumbo phages, are of particular interest due to their unique genetic features. In this study, a novel jumbo bacteriophage, vB_Pae_HU_K1-1, with lytic activity against P. aeruginosa, was isolated from wastewater. Its genome was sequenced and annotated, followed by phylogenetic classification and comparative genomic analyses. The phage’s biological and morphological characteristics were determined using STEM, MOI analysis, and one-step growth curve assays. The cytotoxicity of the phage were evaluated on the HaCaT cells via the MTT test, while its antibiofilm efficacy was assessed using the CV staining. Additionally, homology modelling analyses were conducted for genes encoding lysin, chimallin, and tubulin-like proteins. vB_Pae_HU_K1-1 has a 281,858 bp genome containing 371 CDS. Genome analysis revealed that it belongs to the family Chimalliviridae. However, its intergenomic similarity to the genus Noxifervirus, which showed the highest similarity, was below 70%, suggesting that the phage may represent a novel genus. Homology modelling of chimallin and tubulin-like proteins further supported this classification. Additionally, AcaFinder identified four high-confidence Acr candidates in the vB_Pae_HU_K1-1 genome. In-vitro tests demonstrated that the phage had no cytotoxic effect on HaCaT cells, and biofilm analyses showed that it significantly inhibited P. aeruginosa biofilm formation (p = 0.01). vB_Pae_HU_K1-1 appears to represent a potential new genus within Chimalliviridae, distinguished by its genetic structure and functional characteristics. Its antibiofilm activity and in vitro biocompatibility highlight its potential for future therapeutic and biotechnological research, while contributing to our understanding of the diversity and functional capacity of jumbo phages.