Systematic Evaluation of Phenotypic Variations Induced by Prophages in a Clinical Isolate of Pseudomonas aeruginosa

With the rise of antibiotic resistance, nosocomial infections caused by Pseudomonas aeruginosa present a significant challenge to healthcare systems. Mobile genetic elements, including prophages integrated into bacterial chromosomes, contribute to phenotypic and genotypic diversity, affecting bacterial pathogenicity and complicating antimicrobial treatments. Recent advances in high-throughput sequencing have facilitated the precise localization of prophages within bacterial genomes. However, the mechanisms by which prophages influence host phenotypes remain poorly understood, particularly in clinical polylysogens that harbor multiple prophages. In this study, we conduct a comprehensive investigation of prophages predicted in the clinical P. aeruginosa isolate ZS-PA-05 in the absence of an external trigger, focusing on their contribution to bacterial phenotype through the use of prophage deletion mutants. Our findings indicate that ZS-PA-05 contains both active and potentially cryptic prophages, each exhibiting unique spontaneous induction rates. Notably, the absence of certain prophages significantly affected bacterial growth, motility, biofilm formation, antibiotic susceptibility, and phage proliferation, as well as virulence. Intriguingly, the deletion of prophage WX-Y significantly increased pyocyanin production, enhancing interspecies competition and cell line survival, despite impaired bacterial growth. This highlights the complexity of prophage-host interactions and underscores the role of prophages in bacterial adaptation to hostile environments, with implications for antimicrobial therapies.