|
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 |