Harlequin® E. Coli / Coliform Medium

Harlequin E.coli / Coliform Medium was developed to simultaneously enumerate E.coli and coliforms in food and environmental samples using a dual chromogenic substrate strategy. Tryptone Bile Agar is the base of the medium, which has been modified by the addition of two chromogenic substrates, one to detect the β-glucuronidase enzyme produced by E.coli and another to detect the β-galactosidase enzyme produced by coliforms.

1. Weigh 36.6 grams of powder and disperse in 1 liter of deionized water.
2. Allow to soak for 10 minutes, swirl to mix.
3. Autoclave for 15 minutes at 121°C.
4. Cool to 47°C and mix well.
5. Dispense into Petri dishes.

Typical Formulation g/Liter
Tryptone 20 g
Bile Salts No.3 1.5 g
X-glucuronide 0.075 g
Magenta-β-galactoside 0.1 g
Agar 15 g
Grams per liter 36.6 g

Final pH: 7.2 ± 0.2