Used as a selective and differential culture medium for the detection and isolation of pathogenic microorganisms, particularly in clinical and environmental samples. It supports the growth of certain bacteria while inhibiting others due to the presence of specific dyes and nutrients. The combination of phenol red as a pH indicator and brilliant green as a selective agent allows for the differentiation of lactose fermenters from non-fermenters, commonly used in testing water, food, and stool samples for coliforms and enteric pathogens. Colonies of lactose-fermenting organisms produce acid, causing a color change around the colonies from red to yellow, aiding in quick identification.