India ink

Definition

India ink is a dye used in microbiology for negative staining techniques. It provides a dark background against which transparent organisms, such as capsules around bacteria, can be easily visualized.

5 Must Know Facts For Your Next Test

1. India ink is commonly used to visualize the capsule of Cryptococcus neoformans, a pathogenic yeast.
2. The negative staining technique with India ink does not penetrate the cells but stains the background, making organisms appear as clear halos.
3. India ink is primarily composed of carbon black particles suspended in water.
4. It helps differentiate encapsulated organisms from non-encapsulated ones due to the clear contrast it creates.
5. Microscopic examination with India ink requires minimal preparation and provides rapid results.

Review Questions

• What type of staining technique is India ink used for?
• Why is India ink particularly useful for visualizing Cryptococcus neoformans?
• How does India ink create contrast in microscopic specimens?

Related terms

Negative Staining: A technique in which the background is stained, leaving the specimen unstained and visible.

Capsule Staining: A method specifically designed to observe the capsule surrounding certain microorganisms.

Cryptococcus neoformans:

A pathogenic yeast known for its thick polysaccharide capsule, often visualized using India ink.