An automated system for separation and concentration of food-borne pathogens using immunomagnetic separation

Abstract

In this study, we report an approach for the automated separation and concentration of pathogenic bacteria from food samples as a pretreatment step before detection. We developed an automated immunomagnetic separation (IMS) system, which included pre-enrichment of food samples, incubation with immunomagnetic beads, and separation and concentration of immunomagnetic beads along with bound target bacteria using an automated instrument based on IMS technology. Magnetic recovery bars covered with glass cylinders were utilized for separation of magnetic beads in food samples introduced into collection tubes. The separated magnetic beads with bound bacteria were dispersed in 1 mL phosphate-buffered saline (PBS) in concentration tubes. The efficiency of separation and concentration of the target pathogenic bacteria by the fabricated system were determined using plate counting with E. coli O157:H7 and whole milk as the model target bacteria and real food matrix, respectively. To achieve high concentration and recovery yield, the spiked milk samples were enriched with buffered peptone water before incubation with immunomagnetic beads and introduction into the collection tubes. The entire procedure from pre-enrichment through to concentration was completed within 2 h with the automated IMS system. The proposed approach achieved over 100-fold concentration of inoculated E. coil O157:H7 from milk samples with over 20% recovery of viable cells after pre-enrichment. These results illustrated the feasibility of the developed auto-IMS platform for rapid inspection of food pathogens. (C) 2016 Elsevier Ltd. All rights reserved.