Chance's Method
Principle :
"Bacterial cell is stained pink with new fuschin and then only cytoplasm is decolorized with congored solution while cell wall remains pink"
Mechanism :
* As we know cell wall and cytoplasm are acidic in nature where cell wall is more acidic than cytoplasm.
* So when we apply the first stain that is 0.5% new fuchsine which is the basic stain it stains the cytoplasm as well as the cell wall.
* But here we want to stain the cell wall so the smear is treated with the second stain that is 0.5% congo red solution.
* As we know congo red is a selective decolorizing agent it selectively decolorizes the less acidic portion that is cytoplasm.
* Hence cell wall remains stained by 0.5% new fuchsine stain.
Requirements:
* Clean grease free slide.
* Nichrome wire loop.
* Bacterial suspension.
* New fuchsine solution.
(Basic fuschin - 0.5g; Distilled water - 100ml)
* 0.5% congored solution.
Procedure:
* Take a clean, grease free slide.
* Prepare the smear of the suspension on the clean slide with a loopful of sample.
* Air dry and do not heat fix.
* New fuchsine is poured on smear and kept for about 3-4 minutes and rinse with water.
* Prepare a thin film of congored on dried smear with the help of another slide.
* Air dry, Blot dry and observe under microscope.
Observation:
