Harlequin® E. coli/Coliform Agar, 500g

E. coli / Coliform Agar is for the simultaneous enumeration of Escherichia coli and coliforms in food and environmental samples and is not intended for use in the diagnosis of disease or other conditions in humans.

This dual chromogenic substrate medium makes the different colony types easy to distinguish, allowing rapid counting of both E. coli and coliforms on a single agar.

Based upon the formulation of Tryptone Bile Agar, the medium has been modified by the addition of two chromogenic substrates: one to detect the ß-glucuronidase enzyme (X- glucuronide) and another to detect the ß-galactosidase enzyme (magenta-ß-gal). Typical E. coli strains possess both enzymes but only cleave the X-glucuronide substrate, thereby producing blue-green colonies. Typical coliforms, however, possess only the ß-galactosidase enzyme and produce rose-pink colonies.

The colony types are easily distinguishable, even in the presence of other organisms, or when large numbers are observed, making simultaneous enumeration of E. coli and coliforms a quick and simple procedure.

Typical Formulation

Formula Litre
Tryptone 20.0 g/L
Bile Salt No. 3 1.5 g/L
X-glucuronide 0.075 g/L
Magenta-β-Galactoside 0.1 g/L
Agar 15.0 g/L

Preparation

Suspend 36.6 grams of the medium in one liter of purified water.
Heat with frequent agitation and boil for one minute to completely dissolve the medium.
Autoclave for 15 minutes at 121°C.
Cool to 45–50 °C.

Previous Item Number: This product was previously known as LabM Product: HAL008 Harlequin® E.coli/Coliform Medium