Listeria monocytogenes, as a major causative agent of foodborne illness outbreaks, poses a serious threat to food safety and public health. In complex foodborne pathogen environments, the specific and effective detection methods for L. monocytogenes are crucial. Objective To develop a novel recombinase-aided amplification-exonuclease (RAA-exo) assay for detecting L. monocytogenes. Methods Multiple RAA primer and probe sets targeting hly were designed, and the optimal primer set was selected based on nucleic acid amplification efficiency. The reaction system was rigorously optimized, focusing on the concentrations of A buffer, B buffer, and RAA primers and probe. Results The optimized RAA-exo assay showed a limit of detection (LOD) of 0.5 copies/μL for recombinant plasmids and 10 CFU/mL for L. monocytogenes suspensions. The assay demonstrated high specificity, selectively detecting L. monocytogenes without cross-reactivity to other common foodborne pathogens, including Salmonella, Escherichia coli, Staphylococcus aureus, Bacillus cereus, or other Listeria species (L. ovinae, L. seeligeri, and L. innocua). In a validation study using 44 pork samples, the RAA-exo assay results were in complete agreement with those of the real-time fluorescence PCR internal standard method outlined in the industry standard SN/T 5224—2019. Conclusion The developed RAA-exo assay exhibits high sensitivity and specificity, requires minimal hands-on time, and achieves detection within 20 min at 37 °C. Therefore, the assay is suitable for rapid, on-site testing, serving as an efficient and convenient tool for L. monocytogenes detection, with promising applications in food safety monitoring.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |