Figure 6. Steroid reductase activities are widespread in gut bacteria and elevated in active Crohn’s disease.

(A) Representative images of gut bacteria grown on progesterone-infused media, showing steroid clearance/precipitate accumulation-positive (blue background) and -negative (gray background) colonies. Scale bar, 200 μm. (B) Corticosteroids produced by gut bacterial isolates after incubation with cortisol. The protein with the highest sequence identity to OsrB encoded by each genome was used to generate the tree. (C) Corticosteroids produced by gut bacterial isolates after incubation with prednisolone. Identity refers to the sequence identity of the protein with the highest sequence identity to OsrA encoded by each genome. (D) reads mapping to osrA and osrB homologs in metagenomes from healthy and Crohn’s disease (CD) patients. Only metagenomes with at least one read mapping to a gene are included in the analysis. NQ refers to the not quantified statistical difference, due to the low number of healthy metagenomes with reads mapping to osrA. CPM refers to copies per million. (E) Difference in osrB homolog abundance for taxa showing the greatest changes in relative abundance between healthy and CD metagenomes.