Plasmid-encoded toxin defence mediates mutualistic microbial interactions

Sarah Moraïs, Michael Mazor, Omar Tovar-Herrera, Tamar Zehavi, Alvah Zorea, Morya Ifrach, David Bogumil, Alexander Brandis, Jens Walter, Natalie Elia, Eyal Gur, Itzhak Mizrahi

Research output: Contribution to journalArticlepeer-review


Gut environments harbour dense microbial ecosystems in which plasmids are widely distributed. Plasmids facilitate the exchange of genetic material among microorganisms while enabling the transfer of a diverse array of accessory functions. However, their precise impact on microbial community composition and function remains largely unexplored. Here we identify a prevalent bacterial toxin and a plasmid-encoded resistance mechanism that mediates the interaction between Lactobacilli and Enterococci. This plasmid is widespread across ecosystems, including the rumen and human gut microbiota. Biochemical characterization of the plasmid revealed a defence mechanism against reuterin, a toxin produced by various gut microbes, such as Limosilactobacillus reuteri. Using a targeted metabolomic approach, we find reuterin to be prevalent across rumen ecosystems with impacts on microbial community structure. Enterococcus strains carrying the protective plasmid were isolated and their interactions with L. reuteri, the toxin producer, were studied in vitro. Interestingly, we found that by conferring resistance against reuterin, the plasmid mediates metabolic exchange between the defending and the attacking microbial species, resulting in a beneficial relationship or mutualism. Hence, we reveal here an ecological role for a plasmid-coded defence system in mediating a beneficial interaction.

Original languageAmerican English
Pages (from-to)108-119
Number of pages12
JournalNature Microbiology
Issue number1
Early online date27 Dec 2023
StatePublished - 1 Jan 2024

All Science Journal Classification (ASJC) codes

  • Applied Microbiology and Biotechnology
  • Microbiology (medical)
  • Genetics
  • Cell Biology
  • Microbiology
  • Immunology


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