Gram positive and negative cellwall

Rahul pandey (from TCML Team)
 

Feature

Gram-Positive Bacteria

Gram-Negative Bacteria

Outer Membrane

Absent

Present

Cell Wall Thickness

Thick (50-100 layers)

Thin (1-2 layers)

Peptidoglycan Layer-

• 3rd position of tetra peptide

• Penta glycine bridge

• NAG-NAM

Thick and multilayered

• L-lysine

• Pentaglycin bridge

• Present

Thin

• Meso di amino pimelic acid (DAP)

• Absent

• Present

Composition

• Techoic acid

• X

• Lipoprotein

• Peptidoglycans

• X

• Lipopoly saccharide (LPS)

• Lipoprotein

• Peptidoglycan

Lipid Content

Low (2-5%)

High (15-20%)

Periplasmic Space

Absent

Present

Porins

Absent

Present in the outer membrane

Staining with Gram Stain

Retain crystal violet dye (purple)

Do not retain crystal violet dye (pink/red)

Susceptibility to Penicillin

Generally more susceptible

Generally less susceptible

Toxins Produced

Primarily exotoxins

Endotoxins and exotoxins

Example Organisms

• Staphylococcus

• Streptococcus

• Escherichia coli

• Salmonella

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