There are different types of stains, namely gram stain, capsule stain, endospore stain and acid fast stain. Only acid fast stain is described in this procedure. Click on the other types of staining below to learn about them.
Capsule stain is a type of differential stain which selectively stains bacterial capsules. In the staining procedure, crystal violet serve as the primary stain, and all parts of the cell take up the purple colour of the crystal violet. Copper sulphate solution serve as the decolourizing agent as well as the counter stain. Thus, the capsule appears as faint blue.
- Crystal violet
- Copper Sulphate solution
- Obtain a clean glass slide
- Prepare a smear using 2-3 loopfuls of the broth culture of the organism, allow the smear to air dry.
- Cover the smear with crystal violet and stain for 120 seconds.
- Tilt the glass slide and rinse with copper sulphate solution.
- Let the slide air dry for a few minutes
- Observe the slide under oil immersion
- Keiser, G.E. ‘Laboratory manual’
- Cain, D., Hanks, H., Weis, M., Bottoms, C., and Lawson J. ‘Microbiology Laboratory Manual Biol 2421L Revised Spring Edition’