Rapid Detection of Escherichia coli in Water Using Sample Concentration and Optimized Enzymatic Hydrolysis of Chromogenic Substrates

Curr Microbiol. 2018 Jul;75(7):827-834. doi: 10.1007/s00284-018-1454-8. Epub 2018 Feb 21.

Abstract

Methods for rapid detection of fecal indicator bacteria in water are important to ensure that water is safe for drinking, bathing, recreation, fishing and shellfish harvesting. In this study, we tested experimental conditions for bacterial hydrolysis of two promising enzymatic substrates, 5-Bromo-4-chloro-3-indolyl β-D-glucuronide (X-Gluc) and Resorufin β-D-glucuronide (REG), and optimized parameters such as temperature and pH to determine conditions for rapid reactions. We then innovated a membrane filter-based approach to facilitate more rapid enzyme-based detection of Escherichia coli in water based on the combination of an initial concentration step and optimized test conditions. For this approach, a water sample (10‒100 mL) is filtered through a 0.45-µm pore size filter with a diameter of 4 or 13 mm. After filtration, a newly designed rapid detection broth is added containing the enzymatic inducer Methyl-beta-D-Glucuronide sodium (MetGlu) and the substrate REG or X-Gluc. After a few (1‒7) hours of incubation at 35 °C, the filter shows pink color (for REG-containing broth) or green color (for X-Gluc containing broth) if E. coli is present. The study provides insights and approaches towards developing a simple, fast, and low-cost method to detect fecal indicator bacteria in water.

Publication types

  • Evaluation Study

MeSH terms

  • Biological Assay / instrumentation
  • Biological Assay / methods*
  • Chromogenic Compounds / chemistry*
  • Chromogenic Compounds / metabolism
  • Escherichia coli / enzymology*
  • Escherichia coli / isolation & purification
  • Escherichia coli / metabolism
  • Escherichia coli Proteins / chemistry*
  • Escherichia coli Proteins / metabolism
  • Feces / chemistry
  • Feces / microbiology
  • Fresh Water / microbiology*
  • Glucuronates / chemistry*
  • Glucuronates / metabolism
  • Glucuronidase / chemistry*
  • Glucuronidase / metabolism
  • Hydrolysis
  • Indoles / chemistry*
  • Indoles / metabolism
  • Oxazines / chemistry
  • Oxazines / metabolism
  • Water Pollutants, Chemical / chemistry*
  • Water Pollutants, Chemical / metabolism
  • Water Pollution, Chemical

Substances

  • Chromogenic Compounds
  • Escherichia coli Proteins
  • Glucuronates
  • Indoles
  • Oxazines
  • Water Pollutants, Chemical
  • 5-bromo-4-chloro-3-indolylglucuronide
  • resorufin
  • Glucuronidase