Rapid evolution of microbe-mediated protection against pathogens in a worm host

Kayla C. King, Michael A. Brockhurst, Olga Vasieva, Steve Paterson, Alex Betts, Suzanne A. Ford, Crystal L. Frost, Malcolm J. Horsburgh, Sam Haldenby, Gregory D.D. Hurst

Research output: Contribution to journalArticlepeer-review


Microbes can defend their host against virulent infections, but direct evidence for the adaptive origin of microbe-mediated protection is lacking. Using experimental evolution of a novel, tripartite interaction, we demonstrate that mildly pathogenic bacteria (Enterococcus faecalis) living in worms (Caenorhabditis elegans) rapidly evolved to defend their animal hosts against infection by a more virulent pathogen (Staphylococcus aureus), crossing the parasitism-mutualism continuum. Host protection evolved in all six, independently selected populations in response to within-host bacterial interactions and without direct selection for host health. Microbe-mediated protection was also effective against a broad spectrum of pathogenic S. aureus isolates. Genomic analysis implied that the mechanistic basis for E. faecalis-mediated protection was through increased production of antimicrobial superoxide, which was confirmed by biochemical assays. Our results indicate that microbes living within a host may make the evolutionary transition to mutualism in response to pathogen attack, and that microbiome evolution warrants consideration as a driver of infection outcome.

Original languageEnglish
Pages (from-to)1915-1924
Number of pages10
JournalISME Journal
Issue number8
Early online date15 Mar 2016
Publication statusPublished - 1 Aug 2016


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