Ready gel precast tris hcl polyacrylamide gels

An LPS extraction kit (iNtRON Biotechnology, Korea) was used following the manufacturer’s instruction. LPS was then separated on Ready Gel Precast Tris-HCl polyacrylamide gels with 15% and 5% acrylamide in the separating and stacking gels, respectively (Bio-Rad Laboratories, USA) in buffer with 2% SDS and fixed overnight in buffer with 10% acetic acid and 40% methanol. The gels were stained with a silver staining kit (Bio-Rad Laboratories, USA) following the manufacturer’s instruction. All solutions were prepared fresh before use. The experiment was repeated three times (51 (link)).

The slide agglutination tests were performed using antisera (Ningbo Tianrun Bio-Pharmaceutical Co. Ltd., Zhejiang, China) on the basis of somatic O₇ antigen according to the Kaufmann-White scheme. Test Salmonella in a drop of saline was placed on a slide, and a drop of antiserum was added and mixed. Then the slide was rocked gently for approx. 1 min.
An LPS Extraction kit (iNtRON Biotechnology, Korea) was used following the manufacturer's instruction. LPS was then separated on Ready Gel Precast Tris-HCl polyacrylamide gels with 15% and 5% acrylamide in the separating and stacking gels, respectively (Bio-Rad Laboratories, USA) in buffer with 2% SDS, and fixed overnight in buffer with 10% acetic acid and 40% methanol. The gels were stained with a silver stain kit (Bio-Rad Laboratories, USA) following the manufacturer's instruction. All the solutions were prepared fresh before use. The experiment was repeated three times.

Bacterial total proteins were isolated and analyzed by SDS-PAGE with minor modifications [57 (link)]. All of the mutant and wild-type strains were grown overnight in LB broth at 37 °C to reach the densities of 10⁹ CFU mL^− 1. To characterize the total cellular proteins, the bacterial culture (1 mL) was pelleted by centrifugation (12,000×g, 5 min, 4 °C), suspended in SDS-PAGE loading buffer (20% SDS, 25% glycerol, 0.5% β-mercaptoethanol, 0.06 M Tris–HCl, pH 6.8, 0.15% bromophenol blue) and heated at 100 °C for 10 min. All samples were then separated on Ready Gel Precast Tris-HCl polyacrylamide gels with 15 and 5% acrylamide in the separating and stacking gels, respectively (Bio-Rad, Hercules, CA), and then fixed overnight in buffer with 10% acetic acid and 40% methanol. Gels were stained with 2.5 g L^− 1Coomassie brilliant blue for 2 h. All of the solutions were prepared fresh before use. The experiment was repeated three times.