GRAM STAINING

Introduction:
Gram staining is a method of differentiating bacterial species into two large groups: Gram positive and Gram negative.

Objectives:

1. Differentiate yogurt bacteria (Streptococcus and Lactobacillus)
2. Relate the staining procedure with the structure of the cells.

Material:
- Slide
- Cover slip
- Tongs
- Needle
- Gram stain: crystal violet, iodine and safranin
- Decolorize reagent: ethanol 96%
- Microscope
- Yogurt

Procedure:
1. Fix the piece (yogurt)
2. Add crystal violet (1 minute and 30 seconds)
3. Add water
4. Add Lugol (1 minute)
5. Add water
6. Add ethanol
7. Add safranin (1 minute)
8. Add water

Observations: