Abstract:This study used carboxylated magnetic beads coupled with rabbit polyclonal antibodies to prepare specific immunomagnetic beads.The preparation conditions were optimized，and they were then used in conjunction with a chromogenic medium to establish an immunomagnetic beads-chromogenic plate detection method for the enrichment and separation of Cronobacter sakazakii in powdered infant formula.The results showed that the optimal coupling temperature between the magnetic beads and antibodies was 37°C，with a coupling time of 2.0 h.The optimal antibody dosage for 1 mg of magnetic beads was 200 μg，and the saturation coupling amount was 182.77 μg.The prepared immunomagnetic beads had a concentration range for capturing the target bacteria of 102 to 107 CFU/mL，with a capture efficiency of 68.4%-82.4%，and a reaction rate with nontarget bacteria of less than 10%.The detection method was applied to simulated contaminated samples，and at target bacterial concentrations ranging from 102 to 105 CFU/mL，the capture efficiency was 66.2%-71.5%.Compared with traditional methods，this method reduced the detection time by 2-3 d.