Merck, 81938-500G-F, Coliform ChromoSelect Agar

General description
Coliform ChromoSelect Agar is a chromogenic mixture which contains two chromogenic substrates, Salmon-GAL and X-glucuronide. Coliforms produce an enzyme called β-D-galactosidase, which cleaves Salmon-GAL, resulting in the salmon-to-red coloration of coliform colonies. The enzyme β-D-glucuronidase produced by Escherichia coli cleaves X-glucuronide. Escherichia coli forms dark blue-to-violet colored colonies due to cleavage of both Salmon-GAL and X-glucuronide. The addition of tryptophan improves the indole reaction, thereby increasing detection reliability in combination with the two chromogens. To confirm Escherichia coli, add a drop of Kovac′s reagent (Catalog No. 60983) on the dark blue-to-violet colony. Formation of cherry-red color indicates the positive reaction.
Application
Coliform ChromoSelect Agar is a selective chromogenic medium recommended for simultaneous detection of Escherichia coli and total coliforms in water and food samples.
Preparation Note
Suspend 27 g in 1 litre distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 121°C for 15 minutes. When a high number of gram-positive accompanying bacteria are expected, add 5 mg/l Novobiocin (Cat. No. 74675) before autoclaving of the medium.
Other Notes
We offer two media types: the superior granulated GranuCult® and the cost-efficient powdered NutriSelect® culture media, depending on your needs.
The designations basic, plus, or prime are added to indicate the quality control level, from basic quality control to standard QC plus to prime for full regulatory compliance.
Legal Information
GRANUCULT is a registered trademark of Merck KGaA, Darmstadt, Germany
NutriSelect is a registered trademark of Merck KGaA, Darmstadt, Germany