Sheila/Salmonella agar is _ because _ breaks down amino acids that contain _, such as _ and_. This releases _ which reacts with _ to produce a _ color. Solution Shigella / salmonella agar is differential media because bacteria beaks down amino acids that contains sulfurgroup such as methionine and cystiene.This releases H2S which reacts with indicator ferric ammonium sulfate to produce a black colour.