MacConkey agar is
A) a selective medium.
B) a selective and differential medium.
C) a differential medium.
D) an enrichment medium.
E) an anaerobic medium.

Question

Quizplus · Accepted Answer

MacConkey agar is both a selective and differential medium. It is selective for Gram-negative bacteria and differential for lactose fermentation. The selective agents include bile salts, crystal violet, and neutral red, which inhibit the growth of Gram-positive bacteria. The differential component is lactose, which some Gram-negative bacteria can ferment, leading to the production of acid and a change in the color of the agar from light pink to yellow.

MacConkey Agar Is