To lyse or not to lyse: biasing bacteriophage behaviors

SUMMARY How temperate bacteriophages choose between lysis and lysogeny (dormancy) was one of the very first—and remains among the best studied—models of gene regulation. As over 75% of bacteria have a dormant phage within their genomes, the impact of this decision is far-reaching. It is also underappreciated, with much of microbiology studied independently of this decision; for example, the ubiquitous lab E. coli strain K-12 was cured of phage lambda to make it a “better” model. Here, we review why phages “choose” to lyse or not to lyse, the wide variety of signals they can respond to, how these signals are tapped into by the phage, how the timing of the decision impacts its outcome, and how phages interact around this decision. This decision underpins so much of bacteriology that an understanding of it, and the resulting ability to bias it, will help explain phenomena ranging from failures in culturing bacteria to successes of antibiotic treatments.