Clostridioides difficile LuxS mediates inter-bacterial interactions within biofilms

Slater, R. T.; Frost, L.; Jossi, S.; Millard, A. D.; Unnikrishnan, M.

doi:10.1101/494245

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bioRxiv · 10.1101/494245

Clostridioides difficile LuxS mediates inter-bacterial interactions within biofilms

Slater, R. T.·Frost, L.·Jossi, S.·Millard, A. D.·Unnikrishnan, M.

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Abstract

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.

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Slater, R. T., Frost, L., Jossi, S., Millard, A. D., Unnikrishnan, M.. 2018-12-13. Clostridioides difficile LuxS mediates inter-bacterial interactions within biofilms. https://doi.org/10.1101/494245

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