Description

Multi-drug-resistant bacterial pathogens present one of the largest global health threats, causing 1.3 million deaths annually. The broad use of antibiotics has contributed to the emergence of drug resistance, calling for a desperate need for alternative antimicrobial therapies. Bacteriophages are viruses that specifically infect bacteria and are a leading candidate for treating antibiotic resistant infections. Like all viruses, they are dependent on their host cells, which are highly influenced by environmental factors such as oxygen, temperature, pH, and many others. Phage-host dynamics inside human body are poorly understood, making it crucial to characterize phages under clinically relevant abiotic conditions. Recently, previous data suggest that hypoxia dampens P. aeruginosa phage PAKP1 replication. In this study, we examined the phage-host dynamics of another P. aeruginosa phage PYO2 under hypoxic (14% O2, 5% CO2) and ambient (21% O2, 0.054% CO2) conditions through bacterial and phage growth, adsorption, one-step kinetics and cell saturation assays. Under hypoxia, the Pseudomonas aeruginosa strain PAO1 bacterial growth rate declined, which correlated to a decrease in bacteriophage PYO2 replication over time. However, at a single cell level, there was an increase in phage binding rate but no change in phage progeny release per cell. These results suggest PYO2 possess environmental flexibility to infect and propagate in both hypoxia and normoxia unlike previous reports with PAKP1. Collectively, this suggests that certain phages are capable of infecting bacteria across a wider environmental range. On a broader perspective, characterizing the aptitude of phages across environmental conditions is an important part in selecting candidates for phage therapy.