3.6. SDS-PAGE Analysis of LPS

LPS used for sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis was prepared using the hot aqueous-phenol method, as previously described [30]. The extracted LPS were separated using 12% SDS-PAGE at 50 V for 30 min and 100 V for 2 h, and, subsequently, they were visualized by silver staining using the Fast Silver Stain Kit (no. P0017S, Beyotime, Shanghai, China), according to the manufacturer’s protocol. The gel image was captured using a GS900 Calibrated Densitometer (BioRad Laboratories, Hercules, CA, USA).