Eosin Methylene Blue agar, also referred to as EMB, is both a selective and differential media. It is selective by repressing the growth of gram positives and differential by coloring the colonies of certain certain lactose fermenting gram negatives. Most striking is E. coli which looks a metallic shiny greenish color. Others, such as Enterobacter, show as a pinkish color. The non-fermenters will grow but show no distinctive pigment.