Lab Report

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DATE: 3/25/2010

inal attachment Lab Experiment number 11
To learn the Gram stain technique, the reason for the stain, and how to identify the results of the organisms stained.
Bunsen burner, inoculating loop, staining tray, glass slides, bibulous paper, lens paper, oil, and microscope
Apply Crystal Violet (Primary stain) for 1 minute.
Rinse with D-water
Apply Iodine (Mordant) for 1 minute.
Rinse with D-water.
Apply Alcohol (Decolorize) for 30 seconds.
Rinse with D-water.
Apply Safarin (Counterstain) for 1 minute.
Blot dry with bibulous paper.
E. coli, B. cereus, S. aureus & E.coli (mixture)

E.coli cell shape was bacilli (rod) with a
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Prepared a bacterial smear of M. smegmatic, S. aureus, & a mixture of M. smegmatic & S. aureus 2. Allowed 3 bacterial slides to air dry & then heat fixed over Bunsen burner 8 times. 3. Set up for staining over the beaker on hot plate, flooded smears with primary stain-crystal fuchsin and steamed for 8 minutes. 4. Rinsed slides with water 5. Decolorized slides with acid alcohol until it runs clear with a slight red color. 6. Rinsed with water 7. Counterstained with methylene blue for 2 minutes 8. Rinsed slides with water. 9. Blot dry using bibulous paper and examine under oil immersion

MICROORGANISMS USED: * Mycobacterium smegmatic * S. aureus * A mixture of S. aureus & M. smegmatic

RESULTS AND DATA USED: 1. M.smegmatic, a bacilli bacteria that colored pink resulting in acid fast. 2. S. aureus, a cocci bacteria that colored blue resulting in non acid fast. 3. M.smegmatic & S. aureus resulted in both acid fast & non acid fast.

The conclusion to the acid fast stain is that S. aureus lacks a cellular wax wall causing the primary stain to be easily removed during decolorization, causing it to pick up the counterstain-methylene blue. This results in a non acid fast reaction, meaning it is not in the genus Mycobacterium. M. smegmatic has a

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