FIG 3.

Pathogenic E. coli JJ1886 inhibition by native gut E. coli was acacia fiber dependent. (A and B) Fecal slurry created from stool of mice previously treated with fiber (fiber-treated mouse microbiome) and no fiber (control mouse microbiome) and (A) nonsterile or (B) filter-sterilized. Each well contained 100 μL of fecal slurry, 50 μL of 100 mg/mL fiber, and 50 μL of 10⁶ CFU E. coli JJ1886 (n = 8 per condition). Thick black lines = medians; shaded areas = interquartile range. (C to G) Native gut E. coli (NEC) isolates were combined from the stool of mice previously treated with fiber. E. coli NEC, E. coli JJ1886, or both were cultured with 0, 0.0005, 0.005, 0.05, 0.5, or 1% (wt/vol) fiber at a final concentration of 3 × 10⁶ CFU/mL. CFU were enumerated by plating on nonselective (C, F, and G) and selective (D) agar plates. (E) The ratio of E. coli JJ1886 to total E. coli in coculture was determined by dividing the selective CFU (D) by nonselective CFU (C). Data are medians ± interquartile range. *, P ≤ 0.0001, nonlinear least-squares regression; **, P ≤ 0.01; ***, P ≤ 0.001; **** P ≤ 0.0001; two-tailed Mann-Whitney test.