| Media - MacConkey Agar For the Identification of Bacteria |
MacConkey Agar: Click Here to View Images
MacConkey Agar is used in the identification of E. coli and other gram-
negative enterobacteria.
Growth Characteristics:
MacConkey agar is both a selective and differential agar. MacConkey agar
is inhibitory to gram-positive bacteria, and is indicative of lactose
fermentation. It is selective because it contains bile salts and crystal violet
dye, which inhibit gram positive bacteria from growing. It is also differential,
in that lactose-fermenting bacteria, such as E. coli will produce red
colonies, while bacteria that cannot ferment lactose produce colorless
colonies.
Typical Formulation per Liter:
MacConkey Agar is used in the identification of E. coli and other gram-
negative enterobacteria.
Growth Characteristics:
MacConkey agar is both a selective and differential agar. MacConkey agar
is inhibitory to gram-positive bacteria, and is indicative of lactose
fermentation. It is selective because it contains bile salts and crystal violet
dye, which inhibit gram positive bacteria from growing. It is also differential,
in that lactose-fermenting bacteria, such as E. coli will produce red
colonies, while bacteria that cannot ferment lactose produce colorless
colonies.
Typical Formulation per Liter:
- Peptone 17.0 g
- Proteose Peptone 3.0 g
- Lactose 10.0 g
- Bile Salts No. 3 1.5 g
- Sodium Chloride 5.0 g
- Agar 13.5 g
- Neutral Red 0.03 g
- Crystal Violet 0.001g
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