SCFA analysis
TSS
The SCFA standard mixture was obtained from Sigma-Aldrich (catalog no. CRM46975). A Our LC–MS/MS metabolomics analysis was performed as described previouslyA Waters Acquity UPLC BEH TSS C18 column (2.1 × 100 mm, 1.7 µm) column was used with mobile phase A, consisting of 0.1% formic acid in water, and mobile phase B, consisting of 0.1% formic acid in acetonitrile. The gradient program was as follows: mobile phase B was held at 15% for 1 min, increased to 55% for 19 min, then to 99% for 20 min and held for 2 min before going to the initial condition and held for 4 min. The column was held at 40 °C; 2 µl of sample was injected into the LC–MS with a flow rate of 0.3 ml min