A WT D△ccf F 的么 2 2 B WT E△c 9 ∥ C WTS CIG WT H△cGA Fig. 1. Bacteroides fragilis resides as aggregates on the colon epithelium in a CCF-dependent (A)Representative transmission electron microscopy (TEM) projection and (b) high- resolution tomogram of epithelial-associated wild-type B. fragilis in mono-colonized mice Ascending colons of mice harbored aggregates of B fragilis(green arrow)under non- pathogenic conditions, that made tight associations with the glycocalyx (yellow line) overlying intestinal epithelial cells(lECs, yellow arrow ).(C) Tomogram of wild-type B fragilis penetrating deep into the duct of a crypt of Lieberkuhn. D) Representative TEM projection image and(e)tomogram of epithelial-associated B. fragilis Accf. The absence of the CCF system abrogated formation of bacterial aggregates and prevented intimate association with the glycocalyx. (n=3 mice per group, about I mm epithelium scanned per mouse).(F)Quantification of bacterial cells per projection montage(A and D)of epithelial associated bacteria(unpaired t test, n=7, 8 images from 4 mice per group). (G and H) Tomogram of the bacterial surface of wild-type B. fragilis(G)in comparison to B. fragilis Accf(H)revealed a thick fuzzy capsule for wild-type bacteria residing in the colons of mice ( Measurement of capsule thickness(unpaired t test, n= 10 cells from 3 mice per group) cience. Author manuscript; available in PMC 2018 November 18Fig. 1. Bacteroides fragilis resides as aggregates on the colon epithelium in a CCF-dependent manner (A) Representative transmission electron microscopy (TEM) projection and (B) high￾resolution tomogram of epithelial-associated wild-type B. fragilis in mono-colonized mice. Ascending colons of mice harbored aggregates of B. fragilis (green arrow) under non￾pathogenic conditions, that made tight associations with the glycocalyx (yellow line) overlying intestinal epithelial cells (IECs, yellow arrow). (C) Tomogram of wild-type B. fragilis penetrating deep into the duct of a crypt of Lieberkühn. (D) Representative TEM projection image and (E) tomogram of epithelial-associated B. fragilis Δccf. The absence of the CCF system abrogated formation of bacterial aggregates and prevented intimate association with the glycocalyx. (n = 3 mice per group, about 1 mm epithelium scanned per mouse). (F) Quantification of bacterial cells per projection montage (A and D) of epithelial￾associated bacteria (unpaired t test, n = 7, 8 images from 4 mice per group). (G and H) Tomogram of the bacterial surface of wild-type B. fragilis (G) in comparison to B. fragilis Δccf (H) revealed a thick fuzzy capsule for wild-type bacteria residing in the colons of mice. (I) Measurement of capsule thickness (unpaired t test, n = 10 cells from 3 mice per group) (*** p < 0.001). Donaldson et al. Page 10 Science. Author manuscript; available in PMC 2018 November 18. Author Manuscript Author Manuscript Author Manuscript Author Manuscript