Anaerobic growth of bacterial strains on plates containing soluble (glucose, allantoin), and insoluble (uric acid and adenine) substrates. As detailed in Methods, plates were inoculated with 4 μl of dense overnight cultures grown in rich medium then incubated for 2 days [no fermentable substrate, glucose, allantoin or uric acid conditions] or 7 days (adenine). Growth is indicated by the appearance of cell patches and a zone of clearing for the overlay plates. Details about strains are specified in the Key Resources Table, and a summary of all tested strains is presented in Supplemental Figure 4. Strains indicated in red were used for colonization of gnotobiotic mice.