Recombinase aided amplification combined with lectin-magnetic separation for detection of Staphylococcus aureus in food samples

In contaminated food, Staphylococcus aureus is a threat to human health because it can produce enterotoxins and cause various diseases, therefore, it is important to establish a fast, accurate method to detect S. aureus. In our study, recombinase aided amplification (RAA) combined with lectin-magnetic separation (LMS) was applied to detect S. aureus in skim milk and peach juice. The streptavidin-conjugated magnetic beads (MBs-SA) characterized by Fourier Transform Infrared Spectrometer was used to capture S. aureus. The performance of LMS strategy to capture S. aureus was verified by scanning electron microscope and capture efficiency was obtained in various concentrations of bacteria. The limit of detection (LOD) of this RAA-LMS assay for S. aureus was 3.6 × 10¹ CFU/mL in pure culture, 4.4 × 10⁵ CFU/mL in spiked skim milk and 1.15 × 10³ CFU/mL in spiked juice. Compared with PCR-LMS method, the LOD for RAA-LMS assay was lower, and its sensitivity was improved by three orders of magnitude. Moreover, the detection time of this RAA-LMS method was shorter than that of the standard cultural method. In conclusion, the proposed RAA-LMS assay had a great potential for the rapid and accurate detection of S. aureus.