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.
This product and its use are covered by claims in Glycosynth's patents: European Patents 1438423 and 1438424 and US Patents 7,384,763 and 7,531,646 and 7,709,223.