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Biosensors for Rapid
Detection of Foodborne Pathogens
Chen, Fur-Chi1,
Samuel N. Nahashon1, Suping Zhou1, and
Roger C. Bridgman2
1Institute of
Agricultural and Environmental Research, Tennessee State University,
Nashville, TN 37209; 2Hybridoma Facility, Auburn University,
Auburn, AL 36830
Institute of
Agricultural and Environmental Research
Seminar Series
Tennessee State University, Nashville, TN
April 4, 2007
Salmonella
typhimurium is a major cause of food poisoning associated with animal
and dairy products. Rapid and sensitive surveillances are required to
efficiently detect and ultimately eliminate S. typhimurium
from the food supplies.
Flagella proteins are
immunodominant antigenic surface structures, which provide ideal targets
for sensitive detections. In this study, seven monoclonal antibodies (MAbs)
against flagellar antigens were produced and applied to a surface
plasmon resonance (SPR) sensor for rapid detection of S.
typhimurium.
Antigenic specificity of
MAbs was characterized by enzyme-linked immunosorbent assay (ELISA) and
2-D gel electrophoresis followed by Western blot. The antibodies bound
specifically to the flagellar strain of S. typhimurium. These
MAbs recognized various epitopes present on a group of proteins
migrating between 56 and 58 kD, with an isoelectric point (pI) of 5.2.
The sensitivity and specificity of the SPR sensor were optimized using
serial dilutions of the antibodies. The optimal concentration of
antibody used in the SPR sensor was 0.25mg/ml in a direct assay. The SPR
sensor detect S. typhimurium at the level of 5x106
colony forming units (CFU)/ml from an enriched culture. A detection
limit of 2x104 CFU/ml for S. typhimurium was achieved
when an acid extraction procedure was applied before the sensor
detection. The SPR sensor specifically detected S. typhimurium in
the coexistence of non-pathogenic E. coli at a concentration of
106 CFU/ml. The detection limit was consistent regardless of
an individual MAb or a mixture of the MAbs was used.
The MAbs produced in this
study provide sensitive structural probes that are valuable in
developing biosensors for rapid detection of S. typhimurium.
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