Fundamentals of Microbiology

Staining of Bacteria

Microorganisms are largely composed of water and simply viewing them in a microscope in a wet mount (where they are suspended in water) is like trying to see a white object against a white background. They can be observed better if there is good contract. Therefore, microorganisms must be stained by treating with some dyes before they can be viewed using most microscopes.

There are different staining procedures which include:

i) Simple staining:

This may be either positive or negative staining

ii) Differential staining:

a)   Gram staining      b) Acid-fast staining           

iii) Structural staining:

a) Spore staining

b) Fllagellar staining

c) Capsule staining etc.