Prophage induction contributes to alterations in the gut phageome during intestinal inflammation.

Bacteriophages (phages) are abundant members of the gut microbiota and regulators of bacterial communities. During homeostasis, gut phage communities are longitudinally stable and lysogenic replication is dominant. In chronic gut inflammatory disorders, such as inflammatory bowel diseases (IBDs), there are alterations in phage diversity, which may result from changes in phage replication cycles. Here, we use a combination of in vitro, simplified community, and whole-community bioinformatics approaches to investigate whether prophage induction contributes to these alterations. We identify several compounds associated with gut inflammation that induce prophages from commensal gut bacterial isolates. Analyzing data from two mouse models of colitis, we observe that shifts in the composition of temperate phages occur over the course of inflammation, supporting a switch from lysogenic to lytic replication. Collectively, our observations support the idea that prophage induction contributes to alterations in the phageome associated with intestinal inflammation.