Colilert® 250 is easy to use, rapid and accurate

Easy

• Ease of use simplifies training.
• Unit-dosed packaging eliminates media preparation.
• No repeat testing due to clogged filters or heterotrophic interference.
• Quality Control (QC) procedure can be done in 15 minutes.
  

Rapid

• Under one minute hands-on time.
• Detects coliforms and E. coli simultaneously in 24 hours or less.
• No confirmations needed.
• No glassware cleaning or colony counting.

Accurate

• Suppresses up to 2 million heterotrophs per 100 mL.
• Eliminates the subjective interpretation found in traditional methods.
• Detects a single viable coliform or E. coli per sample.

Economical

• 20 to 50% less expensive than traditional methods. (According to AWWARF Research Application #4).
• Minimizes evening and weekend work.
• Up to 15-month shelf life at room temperature.

Scientific Basis: How Colilert® 250 Works

Colilert 250 uses the patented Defined Substrate Technology® (DST®) to simultaneously detect total coliforms and E. coli. Two nutrient-indicators, ONPG and MUG, are the major sources of carbon in Colilert and can be metabolized by the coliform enzyme β-galactosidase and the E. coli enzyme β-glucuronidase, respectively.

As coliforms grow in Colilert 250, they use β-galactosidase to metabolize ONPG and change it from colorless to yellow.

E. coli use β-glucuronidase to metabolize MUG and create fluorescence. Since most non-coliforms do not have these enzymes, they are unable to grow and interfere.

The few non-coliforms that do have these enzymes are selectively suppressed by Colilert 250's specifically formulated matrix.

This approach is different from traditional media, which provide a nutrient-rich environment that supports the growth of both target organisms and non-targets. When non-targets grow and mimic target organisms, false positives occur. Growth of non-targets can also suppress target organisms and give false negatives in traditional media. To suppress non-targets, traditional media often include high levels of salts, detergents, or other selective agents—which may inadvertently suppress target organisms and give further false negatives.

Colilert 250 Accessories

How to Use Colilert® 250

Presence / Absence (P/A)
Step 1.  Add reagent to sample and incubate 24 hours.
Step 2. Read results: Colourless = negative Yellow = total coliforms Yellow/fluorescent = E. coli

Colilert 250 Questions and Answers