DSS administration causes dysbiosis in rats. (a) Significant differences in the relative abundance of several microbial genera between group C—HST1 and D (no DSS vs. 9 weeks DSS) at the end of the trial (at day 79). (b) Proportion of predicted microbiota from a healthy rat source in rat groups C, D and Dw-DSS, using the SourceTracker software. The vertical, dotted line separates the time points of the 3 weeks in which rats in group Dw-DSS received DSS (left) from the rest of time points in which DSS treatment was withdrawn (right). Significant differences were found between DSS-treated rats and untreated rats (group C—HST1 vs. D) but not between control rats and rats after DSS treatment was withdrawn (group C—HST1 vs. Dw-DSS, at day 60) (Mann-Whitney U test; p < 0.05). (c) Unweighted UniFrac distances between rats in group d-DSS (9 weeks DSS) and UC and CD patients. Significant differences were found, UC patients being closer to rats with DSS-induced colitis than CD patients to this rat model (non-parametric test, p < 0.01). (d) Weighted UniFrac distances between rats with DSS-induced colitis in group d-DSS (9 weeks DSS) and human UC and CD patients. No significant differences were found.