Chromogenic E.Coli Medium 500g

The recovery and enumeration of Escherichia coli and coliforms are important indicators of environmental and food hygiene. Detection of ?-glucuronidase activity is widely used to differentiate Escherichia coli bacteria, as the enzyme, which is encoded by the uidA gene, is present in Escherichia coli, but not other members of the coliform group. As coliforms are lactose-positive, ?-galactosidase activity, encoded by the lacZ gene, is then used to differentiate this group from other organisms able to grow on the selective medium. This results in purple E. coli, as they are able to cleave both chromogens, with other coliforms giving pink colonies as they cleave only the galactoside chromogen. Brilliance E. coli/coliform Selective Agar contains two chromogenic agents: Rose-Gal: detects ?-galactosidase activity X-Glu: detects ?-glucuronidase activity. The medium also contains sodium lauryl sulphate which acts as a selective agent, inhibiting the growth of Gram-positive organisms. Most organisms in the coliform group are able to ferment lactose, so will cleave the pink Rose-Gal chromogen, producing pink colonies. Escherichia coli strains can be differentiated from the other coliforms as they also possess the enzyme ?-glucuronidase (which has been shown to be highly specific to Escherichia coli). The X-Glu chromogen is targeted by this enzyme