Fig. 6: Pyruvate decarboxylase-derived IEt suppresses DSS-induced colitis in mice through AHR activation.

a Schematic diagram of the cloning strategy for the construction and screening of strains with overexpression of IEt-producing enzymes and high production of IEt. b P4013B genome map with annotation of genes involved in the Ehrlich pathway responsible for the biosynthesis of IEt. c Schematic diagram of IEt biosynthetic pathways in P4013B. d PCR analysis of genes encoding IEt-producing enzymes in P4013B. e Western blot analysis of recombinant expression of IEt-producing enzymes in engineered E. Coli BL21 strains. IEt-producing genes with His tag were cloned separately into pET30a(+) plasmids, which were then transduced into E. Coli BL21. f production of IEt in the fermentation broth of engineered E. Coli BL21 strains determined by LC-MS/MS. n = 3 biological replicates (f). g Mice were colonized with E. coli_2062 or E. coli_5239 for two weeks and were administered 3% DSS in drinking water at 15th day to induce acute colitis. h DAI after 3% DSS induction. i Gross morphology and length of colons. j Colonoscopy and H&E-staining of colons. Scale bars, 50 μm. k Plasma concentration of FITC-dextran after oral administration for 4 h. l Immunofluorescence analysis of colonic ZO-1 and CYP1A1. Scale bars, 50 μm. m qPCR analysis of AHR target genes in the colons. n IEt concentrations in the feces of mice determined by LC-MS/MS. Statistics: one-way ANOVA with Dunnett’s test (h, i, k, m, n). The data represent the means ± SEM, n = 6 biological replicates in (h, i, k, m, n). Source data are provided as a Source Data file.