Fig. 3

PSA does not impact B. fragilis niche occupation. a, b SPF WT and GNO WT mice were colonized with 9343 or ΔPSA 9343 for 2 or 8 weeks. Mouse colons were unflushed, formalin-fixed, and FISH-stained: DAPI = blue, B. fragilis 16S probe = red. a Representative FISH-stained mouse colons (2 weeks p.i.); total magnification ×400. Insets show images at total magnification ×630. The stippled line indicates the border between the luminal contents and the epithelial mucus layer. The 9343 and ΔPSA 9343 strains colonize both the lumen and the mucosal surface with patchy mucus penetration (examples are shown with arrows). b Stool and mucosal colonization of mice inoculated with 9343 or ΔPSA 9343. Bars indicate median and interquartile range. Compiled data showing SPF WT stool: 2 to 18 in total per group; SPF WT mucosa: 2 to 10 in total per group; GNO WT stool: 15 to 16 in total per group; GNO WT mucosa: 5 to 6 in total per group