Bacterial resistance to temperate phage is influenced by the frequency of lysogenic establishment

Temperate phages can shape bacterial community dynamics and evolution through lytic and lysogenic life inside and outside the mammalian host. Phages that remained functional despite gene deletions had minimal impact on lysogeny and phage resistance except for deletions in the immI region that substantially reduced lysogeny and increased phage resistance to levels comparable to that observed with an obligately lytic P22. This immI deletion does not make the lysogen less competitive but instead increases the frequency of bacterial lysis. Thus, subtle changes in the balance between lysis and lysogeny during ulation. Our work highlights the complex nature of the phage-bacteria-mammalian host triad.