Dissecting individual pathogen-commensal interactions within a complex gut microbiota community

Abstract

Interactions of commensal bacteria within the gut microbiota and with invading pathogens are critical in determining the outcome of an infection. While murine studies have been valuable, we lack in vitro tools to monitor community responses to pathogens at a single-species level. We have developed a multi-species community of nine representative gut species cultured together as a mixed biofilm and tracked numbers of individual species over time using a qPCR-based approach. Introduction of the major nosocomial gut pathogen, Clostridiodes difficile, to this community resulted in increased adhesion of commensals and inhibition of C. difficile multiplication. Interestingly, we observed an increase in individual Bacteroides species accompanying the inhibition of C. difficile. Furthermore, Bacteroides dorei reduced C. difficile growth within biofilms, suggesting a role for Bacteroides spp in prevention of C. difficile colonisation. We report here an in vitro tool with excellent applications for investigating bacterial interactions within a complex community.