India Ink

Question 1

India Ink

Answer 1

India ink is used in microbiology to identify organisms that have a capsule, such as the yeast, Cryptococcus neoformans. India ink provides a dark background to see the halo of a capsule.

If an organism has a capsule, then the dye is not taken up by the organism. You will see the clear capsule surrounded by dark material, which is the India ink dye.

Question 2

Negative Stain

Answer 2

The background is stained, as opposed to the organism being sought. The morphology of the cell or organism is identifiable as clear against the dark background.

Question 3

India Ink Procedure

Answer 3

1. Add a drop of centrifuged specimen to a microscope slide.
2. Add a drop of India Ink to the specimen.
3. Place a coverslip over the specimen; being careful not to get the specimen on your gloves.
4. Examine the slide starting with the 10X objective and then move to the 40X.
   * * If the slide is too dark, add a drop of saline to the edge of the coverslip to dilute the India ink.

Question 4

India Ink Interpretation of Results

Answer 4

Positive result: The capsule will appear as a well–defined clear zone or halo around the cells.

Negative result: No zone will be present.