Plasmid carriage can limit bacteria-phage coevolution

Ellie Harrison, Julie Truman, Rosanna Wright, Andrew J. Spiers, Steve Paterson, Michael A. Brockhurst

Research output: Contribution to journalArticlepeer-review


Coevolution with bacteriophages is a major selective force shaping bacterial populations and communities. A variety of both environmental and genetic factors has been shown to influence the mode and tempo of bacteria-phage coevolution. Here, we test the effects that carriage of a large conjugative plasmid, pQBR103, had on antagonistic coevolution between the bacterium Pseudomonas fluorescens and its phage, SBW25φ2. Plasmid carriage limited bacteria-phage coevolution; bacteria evolved lower phage-resistance and phages evolved lower infectivity in plasmid-carrying compared with plasmid-free populations. These differences were not explained by effects of plasmid carriage on the costs of phage resistance mutations. Surprisingly, in the presence of phages, plasmid carriage resulted in the evolution of high frequencies of mucoid bacterial colonies. Mucoidy can provide weak partial resistance against SBW25φ2, which may have limited selection for qualitative resistance mutations in our experiments. Taken together, our results suggest that plasmids can have evolutionary consequences for bacteria that go beyond the direct phenotypic effects of their accessory gene cargo.

Original languageEnglish
Article number20150361
JournalBiology letters
Issue number8
Publication statusPublished - 1 Aug 2015


  • Bacteria-phage coevolution
  • Conjugative plasmid
  • Mucoid conversion


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