Water Detect Coliforms

Water Detect Coliforms is a chromogenic medium used for the simultaneous detection of total coliforms and Escherichia coli in the microbiological monitoring of water quality.

Tryptose provides nitrogen, carbon, vitamins and minerals. Sodium Chloride maintains the osmotic balance of the medium. Sorbitol and IPTG are the fermentable carbohydrates. Tryptophan is added to improve the indole reaction. Potassium phosphates act as a buffer. Sodium lauryl sulfate inhibits organisms other than coliform bacteria. X-GAL is the chromogenic substrate cleaved by coliforms. MUG is the fluorogenic substrate highly specific for E. coli.

Use directly the water sample to suspend the powder: 17.1 g of the powder in 1 liter of water.
If tubes or bottles containing pre-weighted powder are used, add 10 ml of water to the tube (ref. 630600) or 100 ml of water to the bottle (ref. 630601).
Shake the tube/bottle to dissolve the powder completely.
Incubate at 37°C for 18-24 h or at room temperature (20-25°C) for up to 48 h.

INTERPRETING RESULTS
Coliforms
Any color change of the broth to blue-green indicates presence of coliforms.
Escherichia coli
Check blue-green broth for fluorescence under long wavelength (366 nm) UV light. A blue fluorescence indicates presence of E. coli.
Confirm E.coli by overlaying the broth with KOVAC’s Reagent (ref. 80271).
The almost immediate development of a red-purple colouring is considered a positive result (positive indole reaction).

Learn more with the product technical sheet