Oxoid™ Brilliance Salmonella Agar Base Chromogenic 5kg Each

Thermo Scientific™ Brilliance™ Salmonella Agar Base (Dehydrated): Isolation and Presumptive Identification of Salmonella Species

Chromogenic Thermo Scientific™ Brilliance™ Salmonella Agar Base provides a reliable method for the isolation and presumptive identification of Salmonella species from food samples.

The medium incorporates an Inhibigen compound, a precisely engineered molecule composed of two components linked by a bond. This bond can only be cleaved by a very specific enzyme. While intact within the medium, the Inhibigen is non-toxic to microorganisms. However, once inside a bacterial cell, if the target enzyme is present, the bond is cleaved, releasing an active inhibitor molecule. This liberated inhibitor then disrupts cell wall synthesis, leading to the death of the target organism. As these inhibited cells die and lyse, free inhibitor is released but cannot be reabsorbed by other cells, ensuring highly targeted inhibition. In Brilliance Salmonella Agar, the Inhibigen specifically targets Escherichia coli. Further inhibition of other competing flora, such as Proteus spp. and Pseudomonas spp., is achieved by the addition of novobiocin and cefsulodin, supplied as a freeze-dried supplement (SR0194).

Differentiation of Salmonella from other organisms capable of growth on Brilliance Salmonella Agar relies on two integrated chromogens, each targeting specific enzymes: caprylate esterase and β-glucosidase. Caprylate esterase is present in all Salmonella strains, as well as in some Klebsiella, Enterobacter, and Proteus species. Organisms possessing caprylate esterase cleave the chromogen, releasing an insoluble purple chromophore that accumulates within growing cells, resulting in distinctive purple-coloured colonies. Conversely, certain Enterobacteriaceae, including Klebsiella and Enterobacter (but notably not Salmonella), possess β-glucosidase. If these organisms grow, they will produce blue or dark blue colonies, even if they are also esterase-positive. This distinct color differentiation facilitates easy distinction from the purple Salmonella colonies.

The corresponding Salmonella Selective Supplement, Part No. SR0194E, is also available.