1. MacConkey\'s media is a selctivave and differential medium has three broad ou
ID: 276977 • Letter: 1
Question
1. MacConkey's media is a selctivave and differential medium has three broad outcomes: pink colonies, colonies that aren't pink, and no growth. (2 points) a. What are the pink colonies using for carbon and energy on MacConkey's Agar? b. What are the white colonies using for carbon and energy on MacConkey's Agar? c. If an organim doesn't grow on MaConkey's agar, but does grow on lactose minimal media, what is your prediction for a lactose fermentation tube? d. If an organism grows pink on MacConkey's agar, but not on glucose minimal media what is your prediction for growth on a lactose minimal media?Explanation / Answer
What are the pink colonies using for carbon and energy on MacConkey's?
Lactose
Organisms that ferment lactose, produce an acidic environment will appear pink .
Lactose are the fermentable carbohydrate providing carbon and energy. Gram-negative bacilli which ferment lactose form pink colonies.
What are the white colonies using for carbon and energy on MacConkey's?
Proteins (or peptides)
If an organism doesn't grow on MacConkey's, what is predication for a lactose fermentation tube?
Cannot predict for a lactose fermentation tube as it could be Gram positive and grow well in a carbohydrate tube.
If an organism grows pink on MacConkey's agar, what is your prediction for growth on a lactose minimal medium?
Cannot predict for growth on a lactose minimal medium as it is possible that this organism requires some nutrient available in MacConkey's which is absent in lactose minimal medium.
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