A rapid and sensitive sandwich assay for the detection of Alicyclobacillus acidoterrestris in apple juice based on magnetosome immunomagnetic separation combined with quantum dots immunoassay technology

The contamination of apple juice by Alicyclobacillus acidoterrestris (A. acidoterrestris) can cause significant economic losses. Therefore, developing a rapid and sensitive method for detecting A. acidoterrestris is necessary. To address this issue, this study prepared magnetosome-monoclonal antibodies immunomagnetic microspheres (IMMs) as capture probes to enrich A. acidoterrestris (IMMs-Aa) and monoclonal antibodies-quantum dots (mAbCdTeQDs) as detection probes for detecting A. acidoterrestris. The obtained IMMs-Aa-mAb-CdTeQDs "sandwich" structure was used to detect A. acidoterrestris based on the fluorescence intensity. The strategy presented a good linear correlation (y = 1048x + 1891, R2 = 0.995) between the fluorescence intensity and the concentration of A. acidoterrestris (101-105 CFU/mL) with a low detection limit of 25.4 CFU/mL within 50 min. The recovery rate of this strategy in spiked apple juice ranged from 88.16 % to 107.03 %. Thus, this study established an efficient and highly sensitive magnetic capture-enrichment-separation-detection method for A. acidoterrestris.