Comparing healthy vs. IBD donor sources was beyond the scope of our study; however, fecal microbiotas from human IBD patients have been previously demonstrated to cause more severe colitis than healthy human microbiota when transplanted to GF mice using both the T-cell transfer to Rag1−/− mouse and Il10−/− mouse models of colitis [26, 39]. This evidence concerns the gene IL10 and colitis.