Question

Which feature allows for the differentiation of Gram Negative (-) microorganisms based on their ability to ferment Lactose?

1) Flagella
2) Pili
3) Cell Wall
4) Capsule

Answer 1

The cell wall is the feature allowing differentiation of Gram-negative organisms based on lactose fermentation, as it is uniquely structured with a thin peptidoglycan layer and an outer membrane containing porins.

Step-by-step explanation:

The feature that allows for the differentiation of Gram-negative microorganisms based on their ability to ferment lactose is the cell wall. This is because the cell wall of Gram-negative bacteria, unlike that of Gram-positive bacteria, contains a thin layer of peptidoglycan surrounded by an outer membrane that includes pore-forming proteins known as porins. During the Gram stain test, these porins can uptake the lactose fermenter indicator (e.g., the pH-sensitive dye in MacConkey agar), allowing for differentiation based on lactose fermentation capabilities.