Buckman LaboratoriesPhotomicrographs

Section:MICROORGANISMS Subsection:METHODS
8 Demonstration of endospores by means of the simple stain
Date Composed: 12-19-95 Date Modified:01-18-96

VIII. Demonstration of endospores by means of the simple stain

A. Materials

1. Microscope slides

2. Crystal violet stain

B. Procedures

1. Flame one side of the slide in the flame of your Bunsen burner to remove any oil
or grease. Allow the slide to cool.

2. Place a drop of water in the center of the slide with your inoculating loop.

3. Transfer some of the bacterium to be stained from the culture to the drop of water
on the slide. Mix.

4. Spread the drop of bacterial suspension out over the slide with your inoculating loop
to form a thin smear about the size of a nickel. Allow the smear to air dry and then
heat fix it.

5. Place the slide on your staining rack and cover the smear with crystal violet stain.
Allow the stain to remain in contact with the smear for one (1) minute. Pour off the
stain, rinse in gently running water, and then blot the slide dry.

6. Examine the slide under the oil immersion lens of your microscope. The bacterial
cells will stain purple. Endospores, if they are present, will not stain and will appear
white.