Hypoxia Increases the Tempo of Phage Resistance and Mutational Bottlenecking of .

Viruses that infect bacteria (i.e., phages) are abundant and widespread in the human body, and new anti-infective approaches such as phage therapy are essential for the future of effective medicine. Our understanding of microenvironmental factors such as tissue oxygen availability at the site of phage-bacteria interaction remains limited, and it is unknown whether evolved resistance is sculpted differentially under normoxia vs. hypoxia. We, therefore, analyzed the phage-bacteria interaction landscape adsorption, one-step, time-kill dynamics, and genetic evolution under both normoxia and hypoxia. This revealed that adsorption of phages to decreased under 14% environmental oxygen (i.e., hypoxia), but phage time-kill and one-step growth kinetics were not further influenced. Tracking the adaptation of to phages uncovered a higher frequency of phage resistance and constrained types of spontaneous mutation under hypoxia. Given the interest in developing phage therapies, developing our understanding of the phage-pathogen interaction under microenvironmental conditions resembling those in the body offers insight into possible strategies to overcome multidrug-resistant (MDR) bacteria.