Final answer:
MacConkey agar is a selective and differential media used in microbiology to distinguish between lactose-fermenting and non-lactose fermenting gram-negative bacteria based on colony color. Lactose-fermenting bacteria will produce pink or red colonies, while non-lactose fermenters will produce colorless or white colonies.
Step-by-step explanation:
MacConkey agar is a type of selective and differential media used in microbiology to distinguish between different types of bacteria based on their ability to ferment lactose. It is primarily used to distinguish between lactose-fermenting and non-lactose fermenting gram-negative bacteria. Lactose-fermenting bacteria will produce pink or red colonies on MacConkey agar, while non-lactose fermenters will produce colorless or white colonies.