Difference between the Cell Wall of Gram Positive and Gram Negative Bacteria

Most of the bacterial cells are surrounded by a thick rigid cell wall. The cell wall provides shape to the cell and protects the bacteria from changes in the osmotic pressure. Peptidoglycan (murein) is the principal component of the bacterial cell wall and it is responsible for the shape and extreme tough nature of the cell wall.

Based on the characteristics of the cell wall, the bacterial cells are classified into Gram Positive and Gram Negative, primarily based on the classical staining reaction called Gram Staining. In the previous post we have discussed about the Similarities and Differences between Gram Positive and Gram Negative Bacteria. Both Gram positive and Gram negative bacterial possess cell wall, however, their structural organization, chemical and physical properties varies. In general, the cell wall of Gram positive bacteria has simpler chemical structures compared to the Gram negative bacteria.

The present post discusses the Differences between the Cell Wall of Gram positive and Gram negative bacteria with a comparison table.

Comparison of the Cell Wall of Gram Positive and Gram Negative Bacteria

Difference between the Cell Wall of Gram Positive and Gram Negative Bacteria

Character	Gram Positive Bacteria	Gram Negative Bacteria
Gram Stained Bacterial Cells
Reacting to Gram staining	Retain the crystal violet stain (primary stain) and appear in purple under microscope	Does not retain the crystal violet stain, appear as pink with safranin (counter stain)
Composition of cell wall	The cell wall primarily composed of peptidoglycan	Cell wall contain three main components – (1) Lipopolysaccharides, (2) Lipoproteins and (3) Peptidoglycan
Cell Wall of Bacteria
Thickness of the cell wall	Comparatively thick and homogenous cell wall.	Comparatively thin and heterogeneous cell wall. 7.5 - 12 nm in thickness
Peptidoglycan layer	Comparatively thick layer	Thin layer
Lipid Content	Less lipid content, 1 – 4%	Comparatively more lipid content, 11 – 22%
Teichoic acid	Teichoic acid present	Teichoic acid absent
Amino acid diversity	Very less amino acid diversity	High amino acid diversity
Aromatic amino acids	Absent	Present
Action as endotoxin	Not act as endotoxin	Acts as endotoxin
Sulfur containing amino acids	Absent in the cell wall	Present in the cell wall
Treated with lysosome	Produce protoplast	Produce spheroplast
LPS	LPS absent	LPS present
Outer membrane	Absent	Present
Porins	Absent (very rarely present)	Present

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