Fig 4.

Tolerance of F. prausnitzii isolates to changes in initial medium pH values and bile salt concentrations. (A) Relative growth rates (h⁻¹) of F. prausnitzii strains on YCFAG medium at three initial pH values (6.7, 6.2, and 5.75) have been represented. For comparison, the growth rate determined for each strain at pH 6.7 is taken as 1.0. (B) Relative OD₆₅₀ after 24 h of F. prausnitzii isolates at four bile salt concentrations (0%, 0.1%, 0.25%, and 0.5%) on YCFAG medium. For comparison, the OD₆₅₀ after 24 h of incubation determined for each isolate in medium without bile salt has been taken as 1.0. Mean growth rates at pH 6.7 and mean OD₆₅₀s in the absence of bile salts for each strain (±standard deviation) were as follows: ●, ATCC 27768 (0.17 ± 0.02 and 0.33 ± 0.05, respectively); ▼, M21/2 (0.32 ± 0.07 and 1.39 ± 0.05, respectively); ■, S3L/3 (0.16 ± 0.02 and 0.52 ± 0.07, respectively); ♦, S4L/4 (0.20 ± 0.02 and 0.63 ± 0.06, respectively); ○, A2-165 (0.55 ± 0.04 and 0.77 ± 0.02, respectively); Δ, L2-6 (0.19 ± 0.01 and 0.47 ± 0.02, respectively); □, HTF-75H (0.15 ± 0.01 and 0.386 ± 0.046, respectively); ♢, HTF-F (0.18 ± 0.01 and 0.826 ± 0.089, respectively). Phylogroup I isolates have been represented in black while phylogroup II isolates are shown in white.