Location: Quality and Safety Assessment Research UnitTitle: Effect of immunomagnetic bead size on recovery of foodborne pathogenic bacteria
|CHEN, JING - US Department Of Agriculture (USDA)|
Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2017
Publication Date: 11/28/2017
Citation: Chen, J., Park, B. 2017. Effect of immunomagnetic bead size on recovery of foodborne pathogenic bacteria. International Journal of Food Microbiology. 267: 1-8.
Interpretive Summary: Timely detection of foodborne pathogen is a high priority for food safety and public health. Current pathogen detection relies on long culture enrichment that takes days to complete. Although numerous alternative detection techniques have been developed to enable fast detection of pathogens within hours, an overnight pre-enrichment step prior to detection is still involved in most of those methods. Immunomagnetic separation (IMS) is a facile technique, which uses antibody coated magnetic beads (IMBs) to selectively capture target pathogens from foods. IMS can further shorten sample preparation to under an hour with added specificity, but its capture efficiency needs to be improved to facilitate more reliable detection. In order to provide insights into means of improvement, we have investigated the influence of IMB size on the recovery of pathogens from food matrices in this study.
Technical Abstract: Long culture enrichment is currently a speed-limiting step in both traditional and rapid detection techniques for foodborne pathogens. Immunomagnetic separation (IMS) as a culture-free enrichment sample preparation technique has gained increasing popularity in the development of rapid detection methods for foodborne pathogens. While the use of magnetic nanoparticles in IMS is on the rise due to substantially larger surface area compared to conventional magnetic microparticles, the effects of immunomagnetic bead (IMB) size on pathogen cell recovery are not fully understood. In this study we compared the IMS recovery and non-specific binding rate using three sizes of IMBs (100, 500, and 1000 nm diameters) targeting at Salmonella Enteritidis. The recoveries of Salmonella from phosphate buffered saline with Tween 20 (PBST) was found to be highest using the 100 nm IMBs (88-96%) followed by 500 nm (31-89%) and 1000 nm (4.1-61%) IMBs, respectively, demonstrating a significant size effect. A similar effect of the IMB size was found in the non-specific binding rates of E. coli (0.21-0.36%, 0.13-0.31%, and 0.05-0.28% for 100, 500, and 1000 nm IMBs, respectively). A 2-72% reduction in Salmonella recovery was observed when IMS was conducted in chicken carcass rinse and liquid egg white samples compared to in PBST. Moreover, this reduction in recovery was more significant using magnetic microparticles (500 and 1000 nm) than nanoparticles (100 nm). However, lower IMS recoveries (10-56%) were found in 100 nm IMBs two months after sample preparation.