False-negative β-d-glucuronidase reactions in membrane lactose glucuronide agar medium used for the simultaneous detection of coliforms andEscherichia colifrom water
| Autor: | B.J. Eldred, Paul S. Warden, M. DeSarno, C.R. Fricker |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
food.ingredient
Lactose medicine.disease_cause Biochemistry Sensitivity and Specificity Applied Microbiology and Biotechnology Agar plate chemistry.chemical_compound Glucuronides food Escherichia coli medicine Agar Water Pollutants Glucuronidase Chromatography biology Escherichia coli Proteins biology.organism_classification Enterobacteriaceae Culture Media chemistry Water Microbiology Glucuronide Bacteria |
| Zdroj: | Letters in Applied Microbiology. 47:539-542 |
| ISSN: | 1472-765X 0266-8254 |
| DOI: | 10.1111/j.1472-765x.2008.02453.x |
| Popis: | Testing for beta-D-glucuronidase activity has become the basis of many methods for the detection of Escherichia coli in both food and water. Used in combination with tests for the presence of beta-D-glucuronidase, these tests offer a simple method for simultaneously detecting coliforms and E. coli. The purpose of this study was to determine the effectiveness of several different procedures in detecting beta-D-glucuronidase activity and hence in detecting E. coli.The ability of membrane lactose glucuronide agar (MLGA), Colilert-18, MI agar, Colitag and Chromocult agar to detect beta-D-glucuronidase activity was tested with over 1000 isolates of E. coli recovered from naturally contaminated water samples. Four of the media gave very similar results but MLGA failed to detect glucuronidase activity in 15.6% of the cultures tested.MLGA had very poor sensitivity for the detection of beta-D-glucuronidase activity in strains of E. coli isolated from naturally contaminated water. This is probably because of the fact that beta-D-glucuronidase activity is pH-sensitive and that acid is formed by E. coli during fermentation of lactose in MLGA.The detection of E. coli in drinking water is the primary test used to establish faecal contamination. The poor sensitivity of MLGA in detecting beta-D-glucuronidase activity suggests that this medium and others containing high concentrations of fermentable carbohydrate should not be used for the detection of E. coli. |
| Databáze: | OpenAIRE |
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