Influence of Biological and Environmental Factors in the Extraction and Concentration of Foodborne Pathogens using Glycan-Coated Magnetic Nanoparticles

Abstract

Rapid detection of foodborne pathogens is essential to preventing foodborne illness outbreaks. Before detection can occur, however, it is often necessary to extract and concentrate bacteria. Conventional methods such as centrifugation, filtration, and immunomagnetic separation can often be time-consuming, ineffective, or costly when working with complex food matrices. This work used cost-effective glycan-coated magnetic nanoparticles (MNPs) for rapid concentration of Escherichia coli O157, Listeria monocytogenes, and Staphylococcus aureus. Glycan-coated MNPs were used to concentrate bacteria from both buffer solution and food matrices while examining the effect of factors including solution pH, bacterial concentration, and target bacterial species. In both pH 7 and reduced pH experiments, successful extraction of bacterial cells occurred in all food matrices and bacteria tested. In neutral pH buffer solution, bacteria were concentrated to 4.55 ± 1.17, 31.68 ± 6.10 and 64.27 ± 16.78 times their initial concentration (mean ± standard deviation) for E. coli, L. monocytogenes and S. aureus, respectively. Successful bacterial concentration occurred in several food matrices, including S. aureus in milk (pH 6), L. monocytogenes in sausage (pH 7), and E. coli O157 in flour (pH 7). The insights gained may facilitate future applications of glycan-coated MNPs to extract foodborne pathogens.

Keywords: Bacteria; Escherichia coli; Food safety; Foodborne illness; Listeria monocytogenes; Staphylococcus aureus.