Variability and host density independence in inductions-based estimates of environmental lysogeny

Ben Knowles, Barbara Bailey, Lance Boling, Mya Breitbart, Ana Cobián-Güemes, Javier Del Campo, Rob Edwards, Ben Felts, Juris Grasis, Andreas F. Haas, Parag Katira, Linda Wegley Kelly, Antoni Luque, Jim Nulton, Lauren Paul, Gregory Peters, Nate Robinett, Stuart Sandin, Anca Segall, Cynthia SilveiraMerry Youle, Forest Rohwer

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)


Temperate bacterial viruses (phages) may enter a symbiosis with their host cell, forming a unit called a lysogen. Infection and viral replication are disassociated in lysogens until an induction event such as DNA damage occurs, triggering viral-mediated lysis. The lysogen-lytic viral reproduction switch is central to viral ecology, with diverse ecosystem impacts. It has been argued that lysogeny is favoured in phages at low host densities. This paradigm is based on the fraction of chemically inducible cells (FCIC) lysogeny proxy determined using DNA-damaging mitomycin C inductions. Contrary to the established paradigm, a survey of 39 inductions publications found FCIC to be highly variable and pervasively insensitive to bacterial host density at global, within-environment and within-study levels. Attempts to determine the source(s) of variability highlighted the inherent complications in using the FCIC proxy in mixed communities, including dissociation between rates of lysogeny and FCIC values. Ultimately, FCIC studies do not provide robust measures of lysogeny or consistent evidence of either positive or negative host density dependence to the lytic-lysogenic switch. Other metrics are therefore needed to understand the drivers of the lytic-lysogenic decision in viral communities and to test models of the host density-dependent viral lytic-lysogenic switch.

Original languageEnglish
Article number17064
Number of pages10
JournalNature Microbiology
Publication statusPublished - 28 Apr 2017
Externally publishedYes


  • Bacteriophages
  • Ecosystem ecology
  • Environmental microbiology
  • Microbial ecology
  • Phage biology


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