Fluorescence detection of Staphylococcus aureus using vancomycin functionalized magnetic beads combined with rolling circle amplification in fruit juice

Staphylococcus aureus is a common foodborne pathogen that can cause a suppurative infection after eating contaminated food. Detection of S. aureus plays an important role in the food industry. In this study, a strategy for the detection of S. aureus using magnetic separation (MS) technology combined with rolling circle amplification (MS-RCA) was proposed. The strategy used antibiotics to capture bacteria and employed RCA products as signal output probes. Vancomycin (Van), as a commonly used antibiotic, can recognize peptidoglycan on the cell wall of Gram-positive bacteria and can effectively identify target bacteria. Therefore, we prepared BSAylated-Van functionalized magnetic beads (Van-MBs) for the pre-enrichment of S. aureus . To ensure the selectivity of this method, we used biotin-pig IgG to bind S. aureus . In addition, to amplify the output signal of the MS-RCA strategy, we introduced streptavidin (SA) and successfully obtained the [email protected] S. aureus @biotin-pig [email protected] @biotin-RCA probe complex and used the biotin-avidin-system (BAS) by combining magnetic separation technology and RCA technology to realize the enrichment and specific detection of S. aureus . Furthermore, by optimizing the experimental conditions such as the magnetic separation time and the amount of Van-MBs, the detection performance of this method was improved. Under the optimal conditions, the detection limit of this method for S. aureus was 3.3 × 10 2  CFU/mL in fruit juice, and it was less affected by other bacteria.