Coliform ChromoSelect Agar is a chromogenic mixture which contains two chromogenic substrates, Salmon-GAL and X-glucuronide. Coliforms produce an enzyme called ß-D-galactosidase, which cleaves Salmon-GAL, resulting in the salmon-to-red coloration of coliform colonies. The enzyme ß-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.
Synonyms: Coliform Agar ChromoSelect
Application: Coliform ChromoSelect Agar is a selective chromogenic medium recommended for simultaneous detection of Escherichia coli and total coliforms in water and food samples.
Legal Information: NutriSelect is a registered trademark of Merck KGaA, Darmstadt, Germany