Simple Microscopes Compound Microscopes Scanning Electron Microscope Transmission Electron Microscope
#4. Identify these stains: (Functions and Reagents)
Simple Stain-
CULTURES: Staphylococcus epidermis slant Bacillus megaterium broth MATERIALS USED: Methylene blue, Distilled water, Slide, Inoculating Loop
FUNCTION: To observe shape size, morphology, and arrangement.
---FROM SOLID: (slant)
1. Mark the smears on the underside. 2. Place 1 to 2 loopfuls of water on the slide. 3. Transfer a small amount of culture with a sterile loop. (Mix with water) 4. Allow the smear to dry at room temperature or heat fix. 5. Cover with methylene blue for 30 seconds and rinse. Blot dry.
---FROM BROTH:
1. Mark the smears on the underside. 2. Place 2 to 3 loopfuls of the liquid culture on the slide with a sterile loop. 3. Spread the bacteria within the circle. 4. Allow the smear to dry at room temperature or heat fix. 5. Cover with methylene blue for 30 seconds and rinse. Blot dry.
NOTES:
Staphylococcus epidermis Staph- Clusters Small blue circles
Bacillus megaterium Strep- Chains Blue rods
What is the purpose of fixing a smear? It denatures bacterial enzymes.
What would happen if too much heat were applied? Cells shapes would distort.
BM SC
Negative Stain
CULTURES: Bacillus subtilus Staphylococcus epidermis
MATERIALS: Nigrosin, Clean slide, Distilled water, Sterile toothpicks
FUNCTION: This technique is very useful in situations where other staining techniques do not show clear morphology or size.
PROCEDURE: 1. Place a small drop of nigrosin near on end of the slide. Mix a loopful of broth culture in the drop. (When from a solid medium, add a loopful of water) 2. Draw a second slide across the surface of the first until it contacts the drop. The drop will spread evenly across the edge of the top slide. 3.