Microbial Staining Methods
Background:
The most of bacteria have refractive indices that are similar to those of the aqueous fluids in
which they are floating and are mostly transparent and colourless. For visualization of the
bacteria, we use stain and dyes.
To improve the clarity of the microscopic image, staining is an adjunct technique used in
microscopic techniques. In the scientific community, stains and dyes are frequently used to
emphasize the structure of biological objects, cells, tissues, etc.
Due to their tiny size, bacteria cannot be observed in great detail under a standard light
microscope unless they are dyed. Due to their varied staining characteristics for particular
bacteria, some staining techniques have significant diagnostic significance. They help to
reveal their internal structure.
Simple Staining:
The act of colouring a bacterial organism only with one stain is known as simple staining.
Requirement:
1. Clean Glass slide
2. Inoculation loop
3. Bunsen burner
4. Microscope
5. Immersion oil
6. 24 hour grown culture of organism
7. Crystal violet or Carbol fuschin.
Procedure:
1. Take a clean glass slide, add loopful of the culture of organism.
2. Allow it to air dry and heat fix the glass slide.
3. Flood smear with Crystal violet or Carbol fuschin, wait for 30 to 60 sec. [1]
4. Wash the slide under running tap water, to remove excess stain. [2]
5. Allow to air dry, then add immersion oil and observe under a microscope (100x).
