Question

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

1) Starch
2) Glucose
3) Lactose
4) Sucrose

Answer 1

Lactose is the substance that allows for the differentiation of Gram Negative (-) microorganisms based on their ability to ferment lactose.

Step-by-step explanation:

The substance that allows for the differentiation of Gram Negative (-) microorganisms based on their ability to ferment lactose is lactose. It is used in various media and tests to distinguish between lactose fermenting and non-lactose fermenting organisms. For example, E. coli is able to ferment lactose, forming pink colonies, while other gram-negative bacteria like Salmonella and Shigella spp. do not ferment lactose and form colorless colonies.