Question

Distinguish E. coli from P. aeruginosa on MAC agar.

A) E. coli forms pink colonies, while P. aeruginosa forms colorless colonies.
B) E. coli ferments lactose, producing pink colonies, while P. aeruginosa does not ferment lactose.
C) E. coli is motile, while P. aeruginosa is non-motile.
D) E. coli is urease-positive, while P. aeruginosa is urease-negative.

Answer 1

On MAC agar, E. coli distinguishes itself by forming pink colonies due to its ability to ferment lactose, whereas P. aeruginosa forms colorless colonies because it cannot ferment lactose.

Step-by-step explanation:

To distinguish E. coli from P. aeruginosa on MAC (MacConkey) agar, one must observe the color of the colonies they form. E. coli can ferment lactose and will produce pink colonies as a result of the fermentation process. On the other hand, P. aeruginosa does not ferment lactose and will therefore form colorless colonies. This property of lactose fermentation is commonly used for pathogen identification in various differential media including MAC agar, which allows for visual differentiation based on the ability to ferment lactose.