Rapid detection of Escherichia coli O157:H7 inoculated in ground beef, chicken carcass, and lettuce samples with an immunomagnetic chemiluminescence fiber-optic biosensor.
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 10(2) to 10(5) 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 x 10(2), 4.4 x 10(2), and 5.5 x 10(2) CFU of E. coli O157:H7 per ml, respectively.
Liu
Yongcheng
Y
Department of Biological and Agricultural Engineering, Center of Excellence for Poultry Science, University of Arkansas, POSC O-411, Fayetteville, Arkansas 72701, USA.
Ye
Jianming
J
Li
Yanbin
Y
D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis; D015374:Biosensing Techniques; D002417:Cattle; D002645:Chickens / Q000382:microbiology*; D015169:Colony Count, Microbial; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D005336:Fiber Optic Technology; D018545:Lactuca / Q000382:microbiology*; D008461:Meat Products / Q000382:microbiology*; D055100:Optical Fibers; D012680:Sensitivity and Specificity
D000907:Antibodies, Bacterial