ReadyPlate™ 55 Chromocult® Coliform Agar plate, 55 mm, for Escherichia coli, for coliforms [Pack of 20]

Description

Application

Mode of Action
The interaction of selected peptones, pyruvate, sorbitol and phosphate buffer promotes rapid colony growth, even for sub-lethally injured coliform bacteria. The growth of Gram-positive bacteria as well as certain Gram-negative bacteria is inhibited by the presence of Tergitol®7 which has no negative effect on the growth of coliform bacteria.
Further, the combination of two chromogenic substrates permits the simultaneous detection of coliform
bacteria and E. coli.

Coliform bacteria detection: The substrate Salmon-GAL is used for the detection of β-D-galactosidase activity, which is characteristic for coliform bacteria. This interaction results in a pink to red color of the coliform colonies.
E. coli detection: The substrate X-glucuronide is used for the detection of β-D-glucuronidase activity, which is characteristic for E. coli.

E. coli cleaves both Salmon-GAL and X-glucuronide, so that positive colonies take on a dark-blue to violet color. These are easily distinguished from other coliform colonies, which have a pink to red color.
Some E. coli (3-4%) are β-D-glucuronidase-negative and appear as pink to red colonies, e.g. most E.coli O157 strains. For the detection of E. coli O157 specific culture media should be used.
Accompanying flora appears as colorless colonies, except for some organisms, which possess β-Dglucuronidase activity. These colonies appear light blue to turquoise in color.