Which medium is commonly used to cultivate Enterobacteriaceae in the laboratory?

Which medium is commonly used to cultivate Enterobacteriaceae in the laboratory?

• A. Blood agar
• B. Nutrient broth
• C. MacConkey agar
• D. chocolate agar

Answer: (C)

MacConkey agar is the medium commonly used to cultivate Enterobacteriaceae in the laboratory. This selective and differential agar specifically inhibits the growth of Gram-positive bacteria while allowing Gram-negative bacteria, such as members of the Enterobacteriaceae family, to grow. The agar contains bile salts and crystal violet, which suppress the growth of non-facultative anaerobes, and it includes lactose and a pH indicator (neutral red) that helps differentiate lactose fermenters from non-lactose fermenters. Enterobacteriaceae that can ferment lactose, such as Escherichia coli, will produce acid and turn the colonies pink, whereas non-lactose fermenters, like Salmonella, will remain colorless. This ability to differentiate based on lactose fermentation makes MacConkey agar particularly valuable for identifying and isolating Enterobacteriaceae in clinical and environmental samples.

MacConkey agar is the medium commonly used to cultivate Enterobacteriaceae in the laboratory. This selective and differential agar specifically inhibits the growth of Gram-positive bacteria while allowing Gram-negative bacteria, such as members of the Enterobacteriaceae family, to grow.

The agar contains bile salts and crystal violet, which suppress the growth of non-facultative anaerobes, and it includes lactose and a pH indicator (neutral red) that helps differentiate lactose fermenters from non-lactose fermenters. Enterobacteriaceae that can ferment lactose, such as Escherichia coli, will produce acid and turn the colonies pink, whereas non-lactose fermenters, like Salmonella, will remain colorless. This ability to differentiate based on lactose fermentation makes MacConkey agar particularly valuable for identifying and isolating Enterobacteriaceae in clinical and environmental samples.