Staining : Definition & Types | Microbiology | Short Notes

Staining simply means coloring of the micro organisms with the dye that emphasizes  and elucidate different important structures of microorganisms including bacteria, virus, protozoa and etc.

Importance of  Staining:

• In microbiology the concept of staining is very important because it highlights the structures of microorganisms allowing them to be seen under a microscope (simple and electron microscope).
• It is also used to differentiate different microorganisms.
• Used for  the identification of microorganisms like bacteria which may b either gram positive or gram negative.

Types of Staining (Microbiology)

1. Simple Stain

• Purpose of Staining : To highlight the total count of  bacteria
• Chemicals : Methylene blue,Carbolfuchsin and Crystal violet

2. Gram Staining

• Purpose of Staining : Gram negative bacteria give pink colour Gram positive bacteria give purple colour
• Chemicals : Safranin and Crystal violet

3. Acid-fast Stain

• Purpose of Staining : To identify the bacteria having cell wall of waxy material
• Chemicals : Mycobacterium tuberculosis and Mycobacterium leprae

4. Special Stain 

• Purpose of Staining : To isolate the specific part of bacteria
• Chemicals : taining of flagella,Staining of endospores and Staining of capsule

5. Neutral stain:

• In neutral stain, both caation and anion are coloured, such that net charge is neutral.
• Neutral stain are actually is a salt of acidic and basic stain.
• Examples: giemsa stain.

6. Basic stain (Cationic stain)

• Chromogen or coloured part of basic stain is positively charged. so, it is also known as cationic stain.
• Basic stain are used to stain negatively charged components such as bacterial cell.
• Examples: methylene blue, safranin, malachite green,basic fuschin, crystal violet