Pseudomonas aeruginosa is a multi-drug resistant bacterial pathogen identified by the World Health Organization as a high-priority target for the development of new treatments. P. aeruginosa has intrinsic resistance mechanisms such as efflux systems and antibiotic-inactivating enzymes and can also acquire resistance with mutations. As an additional adaptive resistance mechanism, adherent P. aeruginosa cells can form a biofilm, shielding the colony from the immune system and from pharmaceutics [1].
Phage therapy is a promising alternative for treating such resistant infections. Bacteriophage LUZ19 is a lytic phage from the Podoviridae family that infects a variety of clinical P. aeruginosa strains [2]. The viral particle consists of an icosahedral capsid cca 60 nm in diameter with 43,5 kbp dsDNA genome packaged inside, and a short tail. The first aim of this project is to characterize the structure of LUZ19 at near-atomic resolution. Phage particles purified on CsCl gradient were used for cryo-electron microscopy data collection; the single-particle analysis of this dataset is in progress. The second aim is to study the interaction of phages with bacterial cells using cryo-electron tomography. Finally, we plan to employ the CRISPR/Cas system to prepare fluorescently labelled phage strains, allowing us to observe the progress of phage infection in bacterial biofilm. Obtained results will further our understanding of LUZ19 infectious cycle in both planktonic and biofilm-forming P. aeruginosa populations.