Issue 6, 2019

Evaluation of the novel substrate RUG™ for the detection of Escherichia coli in water from temperate (Zurich, Switzerland) and tropical (Bushenyi, Uganda) field sites

Abstract

Direct testing of water quality to promote drinking water safety contributes to the sustainable development goals, which call for universal access to safely-managed drinking water services by 2030. Enzyme–substrate tests offer a potentially simple and reliable approach for the detection and quantification of fecal indicator bacteria, including Escherichia coli (E. coli). The novel aquatest (AT) based on resorufin-β-D-glucuronide methyl ester (RUG™) (AT-RUG) is an enzyme–substrate test that overcomes several drawbacks of other established tests. In this study, AT-RUG was used to detect and quantify E. coli in water from temperate (Zurich, Switzerland) and tropical (Bushenyi, Uganda) regions. Quantitative results of AT-RUG were compared with IDEXX Colilert-18® (C-18), m-TEC and m-ColiBlue24®. In temperate waters, AT-RUG was found to be as sensitive as m-TEC (97.0%) and C-18 (98.5%) and showed strong agreement with the reference methods. The false-positive rate for E. coli detection in temperate waters using AT-RUG was 6%. AT-RUG performed well at incubation temperatures of 37 °C and 45 °C, but not at 24 °C. In tropical waters, AT-RUG sensitivity was 94.1% compared to m-ColiBlue24®. AT-RUG detected significantly more E. coli than m-ColiBlue24®, suggesting it is a more conservative estimate. At both field sites, AT-RUG was able to effectively indicate categorical concentrations of E. coli in water samples indicating the level of risks of fecal contamination of water supplies. This study indicates that AT-RUG is a reliable and accurate medium for the detection and quantification of E. coli in temperate and tropical waters.

Graphical abstract: Evaluation of the novel substrate RUG™ for the detection of Escherichia coli in water from temperate (Zurich, Switzerland) and tropical (Bushenyi, Uganda) field sites

Supplementary files

Article information

Article type
Paper
Submitted
16 févr. 2019
Accepted
01 avr. 2019
First published
02 mai 2019
This article is Open Access
Creative Commons BY license

Environ. Sci.: Water Res. Technol., 2019,5, 1082-1091

Evaluation of the novel substrate RUG™ for the detection of Escherichia coli in water from temperate (Zurich, Switzerland) and tropical (Bushenyi, Uganda) field sites

F. Genter, S. J. Marks, G. Clair-Caliot, D. S. Mugume, R. B. Johnston, R. E. S. Bain and T. R. Julian, Environ. Sci.: Water Res. Technol., 2019, 5, 1082 DOI: 10.1039/C9EW00138G

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