Many laboratory techniques, including the Gram-stain, involve making of a smear to view samples microscopically. The goal of making a smear in the laby is to make sample or organisms contained in the specimen to adhere to the slide and prevent the sample from being lost during the staining process. A solid or broth medium can be used to make a smear. The steps for preparing a smear for a Gram-stain are outlined below.
PROCEDURE
1. Use an inoculating wire loop to place one drop of the sample or two loops of liquid bacterial colonies in the center of a clean slide.
2. If you're working with a solid medium or solid samples, use a water bottle to add one drop of water to your specimen. If you're using a broth medium, leave out the water.
3. Using the inoculating loop, completely mix the specimen with the water and spread the mixture out to cover about half of the total area of the slide.
4. Place the slide on a flame and allow it to dry. This process is called “fixing” which can be done chemically or by direct flaming. The smear is now ready for the staining procedure.
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