THE SIMPLE STAIN:
As with ALL REAL STAINING PROCESSES, the Simple Stain is preceeded by the Preparation of a SMEAR! The simple stain is useful in determining the cell size and shape and when different shaped microbes are being examined, it may assist in observing contamination of a pure culture.
As microbes are colorless and somewhat negatively charged, all cationic or positively charged (Basic) dyes may be used for simple staining. The cationic charged dyes are: Basic Fuchsin, Methylene Blue, and Crystal Violet. note: ANY STAIN CAN BE AN ENDOSPORE STAIN (holes)
PROCEDURE:
1) Obtain a slide with a prepared smear.
2) Lay the slide (Smear side-up) on your staining rack in your sink.\
3) Cover the smear with Methylene Blue for 60-120 seconds.
4) Obtain a water spray bottle and aim the water spray ABOVE the smear and wash the excess dye off the smear GENTLY. DO NOT OVERWASH!
5) Shake the excess water off the slide and blot it dry with bibulous paper.
6) View the slide first under 10X and then oil immersion.
NOTE: An unusual and helpful use of Methylene Blue is for live counting with a Micrometer. Methylene Blue stains living cells light blue while dead cells stain black. Methylene Blue is toxic to cells after 15 minutes.
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Describe and differentiate between simple and differential staining!