4.4: MacConkey Agar Flashcards
MacConkey agar is ?? and ?? media for gram-?? organisms, contain indicators to differentiate ?? fermenters from ?? non-fermenters
-selective and differential
-negative
-lactose
Composition of macconkey agar:
-lactose, bile salts, neutral red, and crystal violet
?? and ?? inhibit growth of gram positive
-bile salts and crystal violet
Neutral red dye is a pH indicator that is colorless above a pH of ?? and red at a pH less than ??
-6.8
Red/pink color=
Yellow color=
-ferments lactose, lower pH
-does not ferment lactose
MacConkey agar is used to isolate and differentiate members of the ?? based on the ability to ferment lactose
-enterobacteriaceae
The component or components that inhibit the growth of bacteria on MacConkey agar is/are (Select all that apply)
-crystal violet
-bile salts
You observe yellow-colored colonies growing on MacConkey agar. What does this indicate about the organism?
-the organism do not ferment lactose
You observe red colored colonies growing on MacConkey agar. What does this indicate about the organism?
-the organism is able to ferment lactose
TRUE OR FALSE:
MacConkey agar is used to isolate and differentiate members of the Enterobacteriaceae family based on the ability to ferment mannitol.
-TRUE
MacConkey Agar is often used to isolate and differentiate bacteria in the group:
-enterobacteriaceae
A positive result in the MacConkey agar indicates that a microorganism (Select all that apply)
-ferments lactose
-produces acid end products
Which of the following is not a selective media:
-blood agar
The bile salts in the MacConkey Agar plate serves as
-a selective agent
MacConkey Agar is a selective and differential medium. It selects for ________________ while differentiating between those that can and cannot __________.
-gram negative
-ferment lactose
