Himedia HiCrome Chromogenic Coliform agar (CCA Agar)

It is a selective medium recommended for the simultaneous detection of Escherichia coli and total coliforms in water samples. The medium contains three chromogenic substrates. The enzyme ß-D-galactosidase produced by coliforms cleaves 6-chloro-3-indoxy l-β-D-galactopyranoside to form pink to red coloured colonies. The enzyme ß-D-glucuronidase produced by Escherichia coli, cleaves 5-bromo-4chloro-3-indoxy l- β-D-glucuronic acid. Colonies of Escherichia coli give dark blue to violet coloured colonies due to cleavage of both the chromogens. The presence of the third Chromogenic IPTG enhances the colour reaction. Addition of L-Tryptophan improves the indole reaction thereby increasing the detection reliability. The composition and performance criteria of this medium are as per the specifications laid down in ISO 9308-1:2014.