BISC209: The Gram Stain: Difference between revisions

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6. Flood the slide with the Counterstain Solution (0.6% safranin in 20% ethanol)  for 2 minutes; rinse with water.<br>
6. Flood the slide with the Counterstain Solution (0.6% safranin in 20% ethanol)  for 2 minutes; rinse with water.<br>


7. Blot dry using the bibulous paper package in your benches.  Do not tear out the pages, just insert your slide and pat it dry.  Then observe your stained microbes microscopically following the correct protocol for using the the oil immersion objective on your compound brightfield microscope [[]].  <br>
7. Blot dry using the bibulous paper package in your benches.  Do not tear out the pages, just insert your slide and pat it dry.  Then observe your stained microbes microscopically following the correct procedure for using the the oil immersion objective on your compound brightfield microscope found in this protocol: [[BISC209: Microscopy]].  <br>

Revision as of 09:49, 3 January 2010

Wellesley College-BISC 209 Microbiology -Spring 2010

The Gram Stain

1. Prepare a bacterial smear slide (Find protocol at BISC209: Preparing a bacterial smear slide).
To Gram stain the desired organism(s):
2. Flood the slide with Crystal Violet solution (0.5% crystal violet, 12% ethanol, 0.1% phenol) and stain for 1 minute. (Crystal violet is the primary stain.)

3. Rinse the slide in a very gentle stream of water; drain off excess water by touching the edge of the slide to a paper towel.

4. Flood slide with Gram's Iodine (mordant), let stand for 1 minute, and rinse with a gentle stream of water.

5. Quickly, drip Decolorizing Reagent (80% isopropryl alcohol, 20% acetone) down the length of the slide to remove the excess dye. This step is tricky as it is easy to over- or under-decolorize. IMMEDIATELY rinse with a gentle stream of water.

6. Flood the slide with the Counterstain Solution (0.6% safranin in 20% ethanol) for 2 minutes; rinse with water.

7. Blot dry using the bibulous paper package in your benches. Do not tear out the pages, just insert your slide and pat it dry. Then observe your stained microbes microscopically following the correct procedure for using the the oil immersion objective on your compound brightfield microscope found in this protocol: BISC209: Microscopy.