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DatoValore
TitleIdentification of the faecal indicator Escherichia coli in wastewater through the ?-D-glucuronidase activity: comparison between two enumeration methods, Membrane Filtration with TBX agar and the Colilert®.
AbstractEscherichia coli (E. coli) is one of the most commonly adopted indicators for the determination of the microbiological quality in water and treated wastewater. Two main types of methods are used for the enumeration of this faecal indicator: membrane filtration (MF) and enzyme substrate tests. For both types, several substrates based on the ?-D-glucuronidase activity have been commercialized. The specificity of this enzyme for E. coli bacteria has generated considerable use of methods that identify the ?-D-glucuronidase activity as a definite indication of the presence of E. coli, without any further confirmation. This approach has been recently questioned for the application to wastewater. The present study compares two methods belonging to the above-mentioned types for the enumeration of E. coli in wastewater: MF with Tryptone Bile X-glucuronide agar and the Colilert®-18 test. Confirmation tests showed low average percentages of false positives and false negatives for both enumeration methods (between 4 and 11%). Moreover, the counting capabilities of these two methods were compared for a set of 70 samples of wastewater having different origins and degrees of treatment. Statistical analysis showed that the Colilert®-18 test allowed on average for a significantly higher recovery of E. coli.
SourceJournal of water and health 15 (2), pp. 209–217
KeywordscoliformsEscherichia colifaecal indicatormethodswastewater
JournalJournal of water and health
EditorIWA Publishing, London,
Year2017
TypeArticolo in rivista
AuthorsVergine P., Salerno C., Barca E., Berardi G., Pollice A.
Text370626 2017 coliforms Escherichia coli faecal indicator methods wastewater Identification of the faecal indicator Escherichia coli in wastewater through the D glucuronidase activity comparison between two enumeration methods, Membrane Filtration with TBX agar and the Colilert®. Vergine P., Salerno C., Barca E., Berardi G., Pollice A. IRSA CNR Escherichia coli E. coli is one of the most commonly adopted indicators for the determination of the microbiological quality in water and treated wastewater. Two main types of methods are used for the enumeration of this faecal indicator membrane filtration MF and enzyme substrate tests. For both types, several substrates based on the D glucuronidase activity have been commercialized. The specificity of this enzyme for E. coli bacteria has generated considerable use of methods that identify the D glucuronidase activity as a definite indication of the presence of E. coli, without any further confirmation. This approach has been recently questioned for the application to wastewater. The present study compares two methods belonging to the above mentioned types for the enumeration of E. coli in wastewater MF with Tryptone Bile X glucuronide agar and the Colilert® 18 test. Confirmation tests showed low average percentages of false positives and false negatives for both enumeration methods between 4 and 11% . Moreover, the counting capabilities of these two methods were compared for a set of 70 samples of wastewater having different origins and degrees of treatment. Statistical analysis showed that the Colilert® 18 test allowed on average for a significantly higher recovery of E. coli. 15 Published version Articolo in rivista IWA Publishing 1477 8920 Journal of water and health Journal of water and health J. water health Journal of water and health. carlo.salerno SALERNO CARLO alfieri.pollice POLLICE ALFIERI emanuele.barca BARCA EMANUELE giovanni.berardi BERARDI GIOVANNI pompilio.vergine VERGINE POMPILIO