Fluorogenic assay for rapid detection of Escherichia coli in food
L J Moberg
Applied and Environmental Microbiology
Abstract
An assay procedure to screen for Escherichia coli in foods by using 4-methylumbelliferyl-beta-D-glucuronide (MUG) incorporated into lauryl tryptose (LST) broth was evaluated. The beta-glucuronidase produced by E. coli cleaves the MUG substrate to yield a fluorescent end product. E. coli-negative samples can be identified by lack of fluorescence in LST-MUG within 24 h. MUG was not inhibitory to coliforms and E. coli. Over 1,400 food and dairy samples were tested to compare the standard three-tube most-probable-number procedure with the MUG-containing or non-MUG-containing LST procedure. LST-MUG testing detected a greater number of E. coli, with a lower false-positive rate (1.4%) and in a shorter time, than did the standard procedure. All false-positive results in the LST-MUG testing were attributable to beta-glucuronidase-producing staphylococci. No false-negative result was encountered. Use of MUG in LST broth obviates the EC broth step, allowing a 2.5-day procedure to a completed E. coli test versus the present 4- to 6-day standard most-probable-number method.
Extracted Claims
4 claims extracted from this paper into the knowledge graph
4-methylumbelliferyl-beta-D-glucuronide (MUG) incorporated into lauryl tryptose (LST) broth used to screen for Escherichia coli in foods
“An assay procedure to screen for Escherichia coli in foods by using 4-methylumbelliferyl-beta-D-glucuronide (MUG) incorporated into lauryl tryptose (LST) broth was evaluated”
beta-glucuronidase produced by E. coli cleaves MUG substrate to yield a fluorescent end product
“The beta-glucuronidase produced by E. coli cleaves the MUG substrate to yield a fluorescent end product”
LST-MUG testing detected a greater number of E. coli
“LST-MUG testing detected a greater number of E. coli, with a lower false-positive rate (1.4%) and in a shorter time, than did the standard procedure”