Evaluation of the Pathogen Detect^® System and Anthracene-Based Enzyme Substrates for the Detection and Differentiation of <i>E. coli</i> and Total Coliforms in Water Samples

Abstract

Indirect detection of Escherichia coli and total coliforms can be based on the enzymatic activities of β -glucuronidase ( β-glu ) and β -galactosidase ( β-gal ). These enzymes utilize the substrates anthracene-β-d-glucuronide and pyrene d-galactopyranoside , respectively. Substrate cleavage by the enzyme releases the soluble fluorescent molecules 2-hydroxyanthracene and 1-hydroxypyrene, which can then be detected by a fluorometer. The Pathogen Detect &reg; system is an automated portable unit that can measure fluorescent enzyme products. In this report, we investigated the utility of the Pathogen Detect &reg; system for potential automation of water quality monitoring. The PDS unit has the ability to detect E. coli, mean 14.7 h at a standard deviation of 1.5, when the sample mean is 9.1 cells in 100 mL with a standard deviation of 12.6. Similarly, total coliforms may be detected at mean 14.7 h with a standard deviation of 1.4 when the sample mean is 59.6 cells in 100 mL, with a standard deviation of 144.5. The PDS unit has the ability to detect single cells of either total coliforms or E. coli in 100 mL water sample within 18 hours. Turbidity and color of water samples have no impact on the detection of E. coli and total coliforms.