Dissecting Individual Interactions between Pathogenic and Commensal Bacteria within a Multispecies Gut Microbial Community.

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 models to monitor community responses to pathogens at a single-species level. We have developed a multispecies community of nine representative gut species cultured together as a mixed biofilm and tracked numbers of individual species over time using a quantitative PCR (qPCR)-based approach. Introduction of the major nosocomial gut pathogen, , to this community resulted in increased adhesion of commensals and inhibition of multiplication. Interestingly, we observed an increase in individual species accompanying the inhibition of Furthermore, reduced growth within biofilms, suggesting a role for spp. in prevention of colonization. We report here an tool with excellent applications for investigating bacterial interactions within a complex community. Studying interactions between bacterial species that reside in the human gut is crucial for gaining a better insight into how they provide protection from pathogen colonization. models of multispecies bacterial communities wherein behaviors of single species can be accurately tracked are key to such studies. Here, we have developed a synthetic, trackable, gut microbiota community which reduces growth of the human gut pathogen We report that spp. within this community respond by multiplying in the presence of this pathogen, resulting in reduction of growth. Defined communities that can be tailored to include different species are well suited to functional genomic approaches and are valuable tools for understanding interbacterial interactions.