Glucuronidase Assay in a Rapid MPN Determination for Recovery of Escherichia coli from Selected Foods
Open Access
- 1 January 1987
- journal article
- research article
- Published by Oxford University Press (OUP) in Journal of AOAC INTERNATIONAL
- Vol. 70 (1) , 31-34
- https://doi.org/10.1093/jaoac/70.1.31
Abstract
Glucuronidase is present in most strains of Escherichia coli but absent in most other enteric microorganisms; therefore, an assay for this enzyme is useful for determining the presence of the organism. The substrate 4-methylumbelliferyl beta-D-glucuronide (MUG) is incorporated into either lauryl tryptose (LT) broth or EC medium; the inoculated tubes are then incubated under specified conditions and examined under longwave UV light for the presence of a fluorogenic glucuronidase end product. When compared with the 10-day most probable number (MPN) procedure of AOAC, the LT-MUG and the EC-MUG tests required 24 and 96 h, respectively, and gave comparable mean log MPN values for samples of crabmeat, sunflower kernels, and walnut pieces. However, false-positive and falsenegative reactions were observed with foods tested by both of these rapid methods. Overall, method sensitivity was not compromised by using the LT-MUG rather than the EC-MUG method. Incorporation of 25 αg MUG/mL into LT broth resulted in diminished fluorescence of positive reactions, whereas MUG concentrations of 50 and 100 αg/mL provided decisive fluorogenic reactions.This publication has 2 references indexed in Scilit:
- Loss of plasmids during enrichment for Escherichia coliApplied and Environmental Microbiology, 1981
- RAPID DIAGNOSIS OF ENTEROBACTERIACEAEActa Pathologica Microbiologica Scandinavica Section B Microbiology, 1976