Supplementary material of Phage-based magnetic capture method as an aid for real-time recombinase polymerase amplification detection of Salmonella spp. in milk

Conventional rapid assays for detecting Salmonella in real samples often encounter severe matrix interference or detect the limited number of species of a genus, resulting the inaccuracy of detection. In this study, we developed a method that combined phage-based magnetic capture with real time recombinase polymerase amplification (RPA) for the rapid, highly sensitive, and specific detection of Salmonella in milk with an ultra-low detection limit.

The Felix O-1 phage-conjugated magnetic beads (O-1 pMBs) synthesized in this method showed excellent capture ability for Salmonella spp. and ideal specificity for non-Salmonella strains. After O-1 pMBs-based magnetic separation, the limit of detection (LOD) of the real time RPA assay was 50 CFU/mL in milk samples, which was significantly increased by a magnitude of 3–4 orders. The method exhibited a high sensitivity (compatibility) of 100% (14/14) for all tested Salmonella serotype strains and an ideal specificity (exclusivity) of 100% (7/7) for the tested non-Salmonella strains.