Question

MacConkey agar is selective for gram-negative organisms and contain indicators to differentiate what? A) Lactose-fermenting from non-lactose fermenting organisms

B) Aerobic from anaerobic organisms
C) Gram-positive from gram-negative organisms
D) Acid-fast from non-acid-fast organisms

Answer 1

MacConkey agar is a selective and differential medium used to isolate and differentiate gram-negative organisms based on their ability to ferment lactose.

Step-by-step explanation:

MacConkey agar is a selective and differential medium used to isolate gram-negative organisms. It contains indicators that are able to differentiate between lactose-fermenting and non-lactose fermenting organisms. Lactose fermenters, such as E. coli, will produce pink-colored colonies on MacConkey agar, while non-lactose fermenters will produce colorless colonies.

MacConkey agar is not used to differentiate between aerobic and anaerobic organisms, nor is it used to distinguish between gram-positive and gram-negative organisms or acid-fast and non-acid-fast organisms. Its primary purpose is to selectively isolate and differentiate gram-negative bacteria based on their ability to ferment lactose.