Strand exchange isothermal amplification combined with lateral flow assay strip for rapid detection of Bacillus cereus

Detection of foodborne pathogens is of great significance for ensuring food safety and human health. Therefore, we developed a new detection method, which combined strand exchange isothermal amplification (SEA) with lateral flow assay strip (LFS), for the rapid and simple detection of Bacillus cereus in food. SEA technique is an isothermal nucleic acid amplification method based on the respiration of DNA denatured bubble to achieve a dynamic dissociation state of DNA double strand. The reaction requires only a pair of primers and DNA polymerase. The primers involved in the reaction were modified with biotin and 6-carboxyfluorescein (6-FAM) respectively, which could combine the reaction system with lateral flow assay strip to achieve the result of visualization of reaction results. In this reaction system, the detection sensitivity of B . cereus pure bacterial solution could reach 7.5×10 2 CFU/mL, and the specificity of the reaction system was good. Without enrichment treatment, the detection sensitivity of artificially contaminated rice cake samples and milk samples could reach 8.3×10 3 CFU/mL and 8.3×10 2 CFU/mL, respectively. The results of test strip and amplification were identical, which proved that the system was suitable for the detection of real samples. In addition, the established detection system has great potential as a preliminary detection tool in resource-limited areas.