Fig. 4

Metabolomic analysis of gut microbiota metabolites in each group (* : p < 0.05; ** : p < 0.01). (a) PCA based on intestinal microbiome metabolites; (b) PCoA plot based on intestinal microbiome metabolites; (c) OPLS-DA analysis based on intestinal microbiome metabolites. Volcano plots of differential metabolites among the three groups: (d) H₂-SIBO vs. CH₄-SIBO; (e) healthy control group vs. H₂-SIBO; (f) healthy control group vs. CH₄-SIBO. (g) Heatmap of differential metabolites.