Indoxyl-β-D-glucuronide, a novel chromogenic reagent for the specific detection and enumeration of Escherichia coli in environmental samples

About 97% of Escherichia coli strains produce β-glucuronidase, but almost all other Enterobacteriaceae lack this enzyme. A D-glucopyranosiduronic acid (glucuronide) possessing a readily detectable β-linked aglycone should, therefore, constitute a specific reagent for the detection of this organism. For this purpose, the title compound has been synthesized for the first time. The synthesis proceeds in eight steps from readily available D-glucuronolactone, anthranilic acid, and chloroacetic acid and can be carried out on a large scale. The compound has the predicted properties: when included in the standard membrane filter test for the analysis of water, indoxyl-β-D-glucuronide allows specific detection of E. coli through the formation of blue colonies that are the result of rapid conversion of the liberated aglycone to indigo. The recovery of E. coli is easily measured and almost quantitative.