Figure 6.

Effects of STR exposure on the bacterial tryptophan metabolism in CDDP-induced renal injury model. Eight-week-old wild type male mice (n = 3–5) were orally preexposed to the vehicle or streptomycin (20 mg/mouse) for 24 h and then renal injury was induced with CDDP (20 mg/kg) via intraperitoneal administration for an additional 72 h. The fecal bacteria were subjected to 16S rRNA analysis for the determination of the phylogenetic composition. (A) Genes related to tryptophan metabolism reconstructed from 16S rRNA profile-based metagenomic prediction using PICRUSt2. (B) The blood indoxyl sulfate levels were measured using high-performance liquid chromatography. The different letters represent significant differences between groups using ANOVA with Newman–Keuls method as a post hoc ANOVA assessment (p < 0.05). (C, D) Ehrlich’s test for indole production from Bacteroides acidifaciens. The bacteria were cultured in the Gifu anaerobic media (GAM) broth (C), or minimal media with or without tryptophan (5mg/ml) (D). Results are representative of three independent experiments.