- Education and Science»
- Life Sciences
Gram Staining: Gram positive and Gram negative bacteria
One of the most important cytological features of bacteria is their reaction to a simple procedure called, after its discoverer, the Gram stain. The cell wall of bacteria shows a characteristic reaction to the gram stain devised by C. Gram.
Gram Staining Procedure
The gram staining procedure involves staining cells with the dye crystal violet and all the bacteria will be stained blue. The bacteria are then treated with an iodine solution and decolourized with alcohol. Those bacteria which retain stain are known as Gram positive and those which do not retain the stain are termed as Gram negative. This is the fundamental difference between gram positive and gram negative bacteria.
How Gram Stain works? Gram Staining Principle: Step by step procedure with explanation
- Gram Staining Principle: Step by step procedure with explanation
Reagent Preparation / Step by step procedure& Principle.
Difference between Gram Positive and Gram Negative Bacterial Cellwall
Number of layers
Thin (8-10 nm)
Present in some
Present in all
Petidoglycan, Teichoic acid and lipotechoic acid
Lipopolysaccharide, lipoporteins and peptodoglycan
Striking simplicity of amino acids. Glutamic acid and alanine occur in large amounts
All the amino acids are present
Permeablilty of molecules
Resistance to molecules
List of Gram Negative bacteria
- Escherichia coli (E.coli)
- Cyano bacteria
List of Gram Positive Bacteria