Fig 7. Effect of bile exposure on B. fragilis OMV formation.
(A) Growth of B. fragilis YCH46 in GAM supplemented with the indicated bile concentrations. (B) qPCR was used to determine the relative abundance of the IVp-I-ON or IVp-II-ON genotypes after exposure to the indicated bile concentration. (C) Effect of bile exposure on the expression of an IVp-I-regulated EPS production gene (BF2767) and IVp-II-regulated membrane protein genes (BF3397 and BF3403). (D) OMV production of B. fragilis increased 7-fold after exposure to 5% bile. (E) Schematic of the 3 x FLAG-tag fusion to the C-terminus of the BF3397-encoded protein. (F) Enhancement of the BF3397-encoded membrane protein in response to 5% bile. A B. fragilis YCH46 derivative with a 3 x FLAG-tag sequence fused to BF3397, as shown in panel E, was exposed to 5% bile: the production of BF3397 was assessed by Western blotting with an anti-FLAG antibody. Upper, middle, and lower bands indicate the anti-FLAG tag antibody used for immunoprecipitation, BF3397 (unprocessed form), and N-terminally processed BF3397 (indicated by arrowheads), respectively.