Differences Between Gram Positive and Gram Negative Bacteria

Differences Between Gram Positive and Gram Negative Bacteria

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Differences Between Gram Positive and Gram Negative Bacteria

Differences Between Gram Positive and Gram Negative Bacteria

 S.N.

Character

Gram-Positive Bacteria

Gram-Negative Bacteria
1.    Gram Reaction Retain crystal violet dye and stain blue or purple on Gram’s staining. Accept safranin after

decolorization and stain pink or red on Gram’s staining.
2.    Cell wall thickness Thick (20-80 nm) Thin (8-10 nm)
3.    Peptidoglycan Layer Thick (multilayered) Thin (single-layered)
4.    Rigidity and Elasticity Rigid and less elastic Less rigid and more elastic
5.    Outer Membrane Absent Present
6.  Variety of amino acid in cell wall Few Several
7.  Aromatic and Sulfur-containing amino acid in cell wall Absent Present
8.    Periplasmic Space Absent Present
9.    Teichoic Acids Mostly present Absent
10. Porins Absent Present
11. Lipopolysaccharide (LPS) Content Virtually None High
12. Lipid and Lipoprotein Content Low (acid-fast bacteria have lipids linked to peptidoglycan) High (because of presence of outer membrane
13. Ratio of RNA:DNA 8:1 Almost 1
14. Mesosomes Quite Prominent Less Prominent
15. Flagellar Structure 2 rings in basal body 4 rings in basal body
16. Magnetosomes Usually absent. Sometimes present.
17. Morphology Usually cocci or spore forming rods (exception : Lactobacillus and Corynebacterium) Usually non-spore forming rods (Exception : Neisseria)
18. Endospore formation Some produce endospores during unfavorable conditions. Usually not found to produce endospores.
19. Toxin Produced Exotoxins Endotoxins or Exotoxins
20. Pathogens Few pathogenic bacteria belong to Gram positive group. Most pathogens are Gram negative.
21. Nutritional Requirements Relatively Complex Relatively Simple
22. Resistance to Physical Disruption High Low
23. Cell Wall Disruption by Lysozyme High Low (requires pretreatment to destabilize outer membrane)
24. Susceptibility to Penicillin and Sulfonamide High Low
25. Susceptibility to Streptomycin, Chloramphenicol and Tetracycline Low High
26. Inhibition by Basic Dyes High Low
27. Susceptibility to Anionic Detergents High Low
28.    Resistance to Sodium Azide High Low
29. Resistance to Drying High Low
30. Rendering They can rendered Gram -ve by increasing acidity They can rendered Gram +ve by increasing alkalinity
31. Examples Staphylococcus

Streptococcus

Bacillus

Clostridium

Enterococcus

 Escherichia

Salmonella

Klebsiella

Proteus

Helicobacter

Pseudomonas

Differences Between Gram Positive and Gram Negative Bacteria

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