Isolation and characterization of a novel bacteriophage PUTH1 active against Pseudomonas aeruginosa

Pseudomonas aeruginosa (P. aeruginosa) is a leading cause of healthcare-associated infection and is prone to antibiotic resistance. Treating infections caused by antibiotic-resistant P. aeruginosa remains clinically challenging. The increasing prevalence of multidrug-resistant (MDR) bacteria has prompted the development of alternatives to antibiotics. Bacteriophage (phage) therapy has been regarded as a promising antibacterial alternative in many cases of MDR bacterial infections. This study aimed to isolate and characterize phages with therapeutic potential against MDR P. aeruginosa. Phage PUTH1 was isolated from filtered sewage water collected at Peking University Third Hospital using the double-layer agar spot method. The phage morphology was characterized using transmission electron microscopy (TEM). Subsequently, key biological properties were evaluated, including temperature and pH stability, one-step growth curve, adsorption rate, and optimal multiplicity of infection (MOI). Additionally, the anti-biofilm activity was assessed using crystal violet staining assays. Finally, whole genome sequencing was conducted, followed by comprehensive bioinformatics analysis. Morphological and genomic characterization confirmed that the phage PUTH1 belongs to the Podoviridae family. The phage exhibits remarkable thermal stability (active up to 60 °C) and across a broad pH range (pH 4.0–9.0). Furthermore, the phage is characterized by a short latent period (approximately 30 min), a large burst size (54.5 PFU/cell), and rapid adsorption efficiency, achieving approximately 80% adsorption after 6 min. PUTH1 exhibits significant anti-biofilm activity. The genome of phage was 45,483 bp with 52.25% GC content and contained 70 putative genes; functions were predicted for 32 of them. Phylogenetic analysis revealed that PUTH1 is distinct from currently known phages and belongs to a novel species. The genome sequencing analysis suggested that it does not exist any known virulence and antibiotic resistant genes. Therefore, our findings demonstrate that this novel phage represents a promising therapeutic candidate for treating MDR P. aeruginosa infections.