Phage-bacteria dynamics in spatially structured bacterial communities

Bacteriophage (‘phage’) - viruses that infect and lyse bacteria - can be deployed to treat infections caused by bacterial pathogens. Most reported studies of the therapeutic potential of phage neglect the role of spatial heterogeneity in bacterial communities, e.g., in microcolonies and biofilms. In this study, we investigate the density-dependent dynamics arising from interactions between P. aeruginosa and phage. We utilize high throughput methods such as spectrophotometry and biofilm quantification assays to scan the large parameter space for outcomes. We find that in regions with high initial phage density, bacterial clearance is often followed by reemergence. We further examine the mechanism of phage propagation and their effect on biofilm population using high-resolution time-lapse imaging with spinning disk confocal microscopy. Through experiments and theoretical modeling, we probe the interplay between planktonic and biofilm sub-populations in modulating the outcome of phage-biofilm dynamics.