How to Prepare a Microscope Slide of Bacteria
Heat Fixing a Bacterial Smear for Staining
First, use a wax pencil to draw a circle on the microscope slide to separate each type of bacteria that is going to be sampled.
If a simple stain of only one type of bacteria, or single mixed sample of bacteria is being prepared, no separation is required.
Article Summary: In order to view individual bacteria through a light microscope, a bacterial smear must be attached to a slide and then stained. Here is the procedure.
How to Prepare & Heat Fix a Bacterial Smear
Bacterial smear that has been heat fixed and stained.
In order to heat fix a bacterial smear, it is necessary to first let the bacterial sample air dry. Then either place the slide in the slide holder of a microincinerator, or pass the dried slide through the flame of a Bunsen burner 3 or 4 times, smear side facing up. Once the slide is heat fixed, it can then be stained.
MICROBIOLOGY VIDEO COLLECTION:
How To Prepare a Bacterial Smears
Heat Fixing the Bacterial Sample
Before staining, the sample must be heat fixed. This process accomplishes three things:
- firmly attaches the smear to the microscope slide
- allows the sample to more readily take up the stain
Slides heat fixing on tray attached to microincinerator.
Page last updated 3/2016
How to Prepare a Bacterial Smear for Gram Staining
Preparing a Bacterial Smear
In order to be able to clearly see individual bacteria, a sample of a bacterial colony must be mixed into water or physiological saline. This helps to evenly spread out the bacterial sample.
Placing the Bacterial Sample on the Slide
- Place a drop of water into the wax circle that has been created on the slide.
- Using a sterilized and cooled inoculation loop, obtain a very small sample of a bacterial colony.
- Gently mix the bacteria into the water drop.
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