FIG 2.

Confirmation that BF638R_2714 encodes toxin activity. (A) Placement of BF638R_2714 in trans (p2714) in B. thetaiotaomicron VPI-5482 conferred growth inhibitory activity against all three B. fragilis strains. (B) Deletion of BF638R_2714 in the 638R Δbsap-1 Δubb (ΔΔ) background, resulting in 638RΔΔΔ, abrogated toxin activity that is partially restored when the gene is added in trans. (C) Purified His-tagged 2714 demonstrates toxin activity in a dose-dependent manner against the three sensitive B. fragilis strains but not against resistant strain NCTC 9343. (D) Venn diagram of the sensitivity of the 34 B. fragilis strains analyzed in this study against each of the three diffusible toxins produced by B. fragilis 638R.