Difference Between Gram-positive and Negative Bacterial Cell Wall in Table

Gram-Positive Bacteria

They are stained purple with this staining technique. They form a CV- 1 complex (Crystal violet complex 1) and retain the primary dye color. Gram-positive bacteria have a simple cell wall. IT has a large amount of fo peptidoglycan. It has a lesser amount of lipopolysaccharide. 

Examples: Staphylococcus, Bacillus, Corynebacterium

There are following characteristics are generally present in a Gram-positive bacteria: 

  1. They have cytoplasmic lipid membranes.
  2. Gram-positive bacteria have only one membrane layer.
  3. They have a thick peptidoglycan layer. Teichoic acid and lipids are present. They form lipoteichoic acid. It acts as chelating agents. It also used for certain types of adherence.
  4. Capsule polysaccharides (only in some species).
  5. Flagellum (only in some species) it present, it contains two rings for support.

Gram-Negative Bacteria

They are stained pink with this staining technique. They retain secondary dye color. Gram-negative have a lesser amount of peptidoglycan. It has a more complex structure. An outer membrane of lipopolysaccharides is present outside the layer of peptidoglycan. Gram-negative species are more dangerous than gram-positive bacteria. The lipopolysaccharide layer is often toxic. This layer protects the bacteria from the immune system of the host. Gram-negative bacteria are more resistant to antibiotics. Its examples are pseudomonas. There are the following characteristics of Gram-negative bacteria:

  1. They also have a cytoplasmic membrane
  2. They have thin peptidoglycan layer(much thinner than in Gram-positive bacteria) 
  3. The outer membrane containing lipopolysaccharide outside the peptidoglycan layer
  4. Porins exist in the Outer Membrane. It acts like pores for particular molecules. 
  5. There is a space gap b/w secondary cell membrane and layers of peptidoglycan. It is called the periplasmic space.
  6. The S-layer is directly attached to the outer membrane, rather thane the peptidoglycan.
  7. If present, flagella may have 4 supporting rings instead of 2.
  8. No teichoic acids are lipoteichoic acids are present 
  9. Lipoproteins are attached to the polysaccharide backbone

Cell Wall Difference in Table

ComponentGram-Positive BacteriaGram-Negative Bacteria
Inner Rigid wall layer
Outer layer wall
Teichoic Acid+

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