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.
This product and its use are covered by claims in Glycosynth's patents: European Patent 1438423 and US Patent 7,531,646.