Rapid Detection of Escherichia coli O157:H7 Inoculated in Ground Beef, Chicken Carcass, and Lettuce Samples with an Immunomagnetic Chemiluminescence Fiber-Optic Biosensor
Abstract:A biosensor was evaluated with regard to its usefulness in the rapid detection of Escherichia coli O157:H7 inoculated in ground beef, chicken carcass, and romaine lettuce samples. The biosensor consisted of a chemiluminescence reaction cell, a fiber-optic light guide, and a luminometer linked to a personal computer in conjunction with immunomagnetic separation. The samples inoculated with E. coli O157:H7 were first centrifuged and suspended in buffered peptone water and then incubated with anti-E. coli O157 antibody-coated magnetic beads and horseradish peroxidase (HRP)-labeled anti-E. coli O157 antibodies to form antibody-coated bead-bacterium-HRP-labeled antibody sandwich complexes. Finally, the sandwich complexes were separated from the samples in a magnetic field and reacted with luminol in the reaction cell. The number of E. coli O157:H7 cells was determined by collecting the HRP-catalyzed chemiluminescence signal from the bead surface through a fiber-optic light guide and measuring the signal with a luminometer. The chemiluminescence biosensor was specific for E. coli O157:H7 in samples containing other bacteria, including Salmonella Typhimurium, Campylobacter jejuni, and Listeria monocytogenes. The chemiluminescence signal was linear on a log scale from 102 to 105 CFU of E. coli O157:H7 per ml in samples. Detection could be completed within 1.5 h without any enrichment. The detection limits for ground beef, chicken carcass, and lettuce samples were 3.2 × 102, 4.4 × 102, and 5.5 × 102 CFU of E. coli O157:H7 per ml, respectively.
Document Type: Miscellaneous
Affiliations: 1: Department of Biological and Agricultural Engineering, Center of Excellence for Poultry Science, University of Arkansas, POSC O-411, Fayetteville, Arkansas 72701 2: Nutrition and Food Science Research Center, University of Rhode Island, West Kingston, Rhode Island 02892, USA
Publication date: March 1, 2003
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