P. Bouvrette et Jht. Luong, DEVELOPMENT OF A FLOW-INJECTION ANALYSIS (FIA) IMMUNOSENSOR FOR THE DETECTION OF ESCHERICHIA-COLI, International journal of food microbiology, 27(2-3), 1995, pp. 129-137
A flow injection immunoanalysis (FIA) system has been developed for th
e detection of Escherichia coli in artificially contaminated food samp
les. Anti-E. coli antibodies were covalently immobilized onto porous a
minopropyl glass beads via glutaraldehyde activation to form an immuno
reactor. After adsorption of the cells onto anti-E. coli antibody boun
d glass beads, 4-methylumbelliferyl-beta-D-glucuronide was injected in
to the system which was then hydrolyzed by the adsorbed E, coli cells
containing beta-D-glucuronidase, an enzyme which is very specific to E
. coli and to a few other strains of Shigella. Fluorescent 4-methylumb
elliferone released from the enzymatic reaction was then detected by a
fluorometer. Owing to the specificity of the antibody towards E. coli
, the FIA system was very selective for detection of E. coli whereas S
higella boydii, another GUD-positive bacterium, did not give any respo
nse. The FIA system was successfully used for detecting as low as 5x10
(7) CFU/ml E, coli in less than 30 min and was reusable for at least 3
00 repeated assays. The immunoreactor yielded reproducible results dur
ing 3 months of experimentation if stored overnight at 4 degrees C in
carrier buffer containing 0.05 to 0.25% Tween 20.