This SuperSeries is composed of the following subset Series: GSE5865: B.thetaiotaomicron or B. longum mono-association versus B. thetaiotaomicron/B. longum co-colonization, PR chow, NMRI GSE5866: B.thetaiotaomicron mono-association versus B. thetaiotaomicron co-colonization with B. longum, PR chow, B6 GSE5867: B.thetaiotaomicron mono-association versus B. thetaiotaomicron co-colonization with B. animalis or L. casei, PR chow, B6 Refer to individual Series