Substrate producing highly visible, localised, black or dark brown colonies when used in conjunction with an iron salt. This dark colour is able to mask the colour formed by indoxyl substrates such as X-Gal (70045) when incorporated into the same medium. Can also be used to produce discrete yellow colonies in the presence of aluminium salts.
Picture : Intense black colonies of beta-glucosidase-positive Enterococcus faecalis stand out sharply from the cream colonies of Staphylococcus aureus which do not express this enzyme, even where the colonies are practically coincident.
The use of this product is covered by Glycosynth's patents: European Patent 1438423 and US Patent 7,531,646.