Clostridioides difficile LuxS mediates inter-bacterial interactions within biofilms

Sci Rep. 2019 Jul 9;9(1):9903. doi: 10.1038/s41598-019-46143-6.


The anaerobic gut pathogen, Clostridioides difficile, forms adherent biofilms that may play an important role in recurrent C. difficile infections. The mechanisms underlying C. difficile community formation and inter-bacterial interactions are nevertheless poorly understood. C. difficile produces AI-2, a quorum sensing molecule that modulates biofilm formation across many bacterial species. We found that a strain defective in LuxS, the enzyme that mediates AI-2 production, is defective in biofilm development in vitro. Transcriptomic analyses of biofilms formed by wild type (WT) and luxS mutant (luxS) strains revealed a downregulation of prophage loci in the luxS mutant biofilms compared to the WT. Detection of phages and eDNA within biofilms may suggest that DNA release by phage-mediated cell lysis contributes to C. difficile biofilm formation. In order to understand if LuxS mediates C. difficile crosstalk with other gut species, C. difficile interactions with a common gut bacterium, Bacteroides fragilis, were studied. We demonstrate that C. difficile growth is significantly reduced when co-cultured with B. fragilis in mixed biofilms. Interestingly, the absence of C. difficile LuxS alleviates the B. fragilis-mediated growth inhibition. Dual species RNA-sequencing analyses from single and mixed biofilms revealed differential modulation of distinct metabolic pathways for C. difficile WT, luxS and B. fragilis upon co-culture, indicating that AI-2 may be involved in induction of selective metabolic responses in B. fragilis. Overall, our data suggest that C. difficile LuxS/AI-2 utilises different mechanisms to mediate formation of single and mixed species communities.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Bacteroides fragilis / drug effects
  • Bacteroides fragilis / growth & development*
  • Bacteroides fragilis / metabolism
  • Biofilms / drug effects
  • Biofilms / growth & development*
  • Carbon-Sulfur Lyases / genetics
  • Carbon-Sulfur Lyases / metabolism*
  • Clostridioides difficile / drug effects
  • Clostridioides difficile / growth & development*
  • Clostridioides difficile / metabolism
  • Gene Expression Regulation, Bacterial*
  • Homoserine / analogs & derivatives*
  • Homoserine / pharmacology
  • Lactones / pharmacology*
  • Mutation
  • Quorum Sensing*
  • Signal Transduction


  • Bacterial Proteins
  • Lactones
  • N-octanoylhomoserine lactone
  • Homoserine
  • Carbon-Sulfur Lyases
  • LuxS protein, Bacteria