Rapid Detection of Salmonella typhimurium and Staphylococcus aureus in Beef by Immunomagnetic Separation Combined with Loop-Mediated IsothermaL Amplification Method
Lü Guan, CHANG Yanlei, SHI Lei
Institute of Food Safety and Nutrition, Jinan University, Guangzhou 510632, China
Abstract：A method combining immunomagnetic separation (IMS) and loop-mediated isothermal amplification (LAMP) was developed to detect Salmonella typhimurium and Staphylococcus aureus in beef. Streptavidin magnetic beads were functionalized with biotin-labeled Salmonella typhimurium antibodies and biotin-labeled Staphylococcus aureus protein antibodies to capture and isolate the target pathogen from beef. After optimization, 400 μL of immunomagnetic beads (IMBs) conjugated with 10 μL/mg of anti-Salmonella typhimurium antibody presented a capture efficiency of 52.16% for 104 CFU/mL of Salmonella typhimurium within 45 min, and 300 μL of IMBs conjugated with 6 μL/mg of anti-Staphylococcus aureus antibody presented a capture efficiency of 56.80% for 104 CFU/mL of Staphylococcus aureus within 30 min. The proposed IMS-LAMP had a high specificity. When applied on beef, the detection limit was about 1.2 × 103 CFU/mL for Salmonella typhimurium and 4.4 × 104 CFU/mL for Staphylococcus aureus in beef. After 5 and 7 h of enrichment, the detection limit of Salmonella typhimurium and Staphylococcus aureus was improved to 1.2 and 4.4 CFU/mL, respectively. Hence, the IMS-LAMP assay provides a rapid, simple, and highly sensitive method for the detection of Salmonella typhimurium and Staphylococcus aureus in beef.
2019, Vol. 33 
