Question

list the steps of the gram staining procedure in order and fill in the color of gram positive cells and gram negative cells after each step

Answer 1

The Gram stain is developed by Danish physician Christian Gram in 1884.

Gram staining is a differential staining that are used to distinguish organisms based on their staining properties.

The steps of gram staining procedure are described below...

1. Take a clean grease free slide

2. Prepare a smear of bacteria on the slide

3. Air dry and then heat-fix the smear over flame

4. Apply few drops of crystal violet stain on slide and keep it for 2-60 second (Depending upon the strength of the stain).

5. Rinse slide with distilled water.

6. Apply few drop's of Gram Iodine on the slide and keep it for 20-30 second.

7. Rinse the slide in distilled water again.

8. Wash the slide with 95% ethyl alcohol for 10-20 second

9.a. If bacteria retain dark-violet or purple colour (Gram positive).

9.b. If the bacteria lose the stain (Gram-negative)

10. Wash the slide with distilled water and counter-stain with safranin for 30 second and again wash with distilled water.

11.a. No change by counter-staining and bacteria retain dark-violet or purple colour (Gram positive)

11.b. Bactrtia become red (Pink) (Gram negative)