(a) Schematic diagram of experiment: genetically tractable gut microbiota were isolated from the mouse microbiome in vitro and then orally gavaged to recolonize the gut. (b) MGB3, MGB4, and MGB9 strains orally gavaged into mice (n = 4) as a mixture recolonized the GI tract without any antibiotic treatment. MGBs were detectable in fecal samples for at least 15 d post-gavage. (c) MGB strains (namely, MGB4) were present in all sampled locations along the GI tract when the mice (n = 4) were euthanized 15 d post-gavage. Error bars represent s.d. (d) Phylogenetic tree of FACS-sorted GFP+mCherry– transconjugants in fecal samples from mice after 11 d post-gavage of MGB strains. Fecal samples from 4 mice were combined for analysis. Relative abundance of each OTU in the unsorted population is shown in the grayscale heat map, and fold enrichment for transconjugants of each OTU is shown in the orange heat map. Bracketed values indicate confidence of taxonomic assignment by RDP Classifier. The red asterisk denotes the Escherichia/Shigella OTU that shares a genus with the MGB4/9 donors.