Bacteria are broadly classified as gram-positive and gram-negative bacteria based on gram stain. But both of the groups are Prokaryotic cells similar in many aspects. Check the similarities at the end after the table.
Differences between gram positive and gram negative bacteria
| Sl.No | Features | Gram +ve Bacteria | Gram -v Bacteria |
|---|---|---|---|
| 1 | Gram Stain Reaction | In gram staining, the crystal the violet dye will be retained on the cell wall after washing with the de-staining solution. | The de-staining solution will remove the color of the crystal violet dye. |
| 2 | Microscopic view | The gram-positive bacteria will stain blue or purple color under a microscope, because it retains the crystal violet dye | The gram-negative bacteria will stain pink or red color under a microscope because it accepts the safranin dye. |
| 3 | Cell wall | In the gram-positive bacteria the cell wall is a single layer (contains plasma membrane) | In the gram-negative bacteria the cell wall is double layered (contains plasma membrane and outer membrane) |
| 3 | Cell wall Shape | The gram-positive bacteria contain flat and even cell walls. | The gram-negative bacteria contain wavy and uneven cell walls. |
| 4 | Elasticity | The cell wall is very rigid, so it has less elasticity. | The cell wall is less rigid, so it has high elasticity. |
| 5 | Peptidoglycan | The proportion of peptidoglycan present in the gram-positive bacteria is 80% because the cell wall is very rigid. | The proportion of the peptidoglycan present in the gram-negative bacteria is 2-12%, because of the cell wall has high elasticity. |
| 6 | Thickness | The gram-positive bacteria,15-20nm thickness, varies depends upon the cell. Some of the bacteria contain an 80nm thickness cell wall. | The gram gram-positive bacteria have a 7.5-12nm thickness of the cell wall. |
| 7 | Muramic Acid Content | The muramic acid content in the gram-positive bacteria is 16-20%. | The muramic acid content in the gram-negative bacteria is 2-5%. |
| 8 | Resistant | The cell wall is insoluble in the 1% KOH solution, so it is resistant to the alkali. | The cell wall is soluble in the 1% KOH solution, so it is sensitive to the alkali. |
| 9 | Physical Disruptions | Mostly that the gram-positive cell is highly resistant to the physical disruptions. | Gram-negative bacteria is less resistant to physicial damage |
| 10 | S-layer in cell wall | In the cell wall of the gram-positive bacteria, the S-layer is attached to the peptidoglycan layer. | n the gram-negative bacteria, the S-layer is attached to the outer membrane. |
| 11 | Teichoic acid | teichoic acid is present in the cell wall. | teichoic acid is absent in their cell wall |
| 12 | Periplasmic space | The gram-positive bacteria do not have the periplasmic space. | The gram-negative bacteria have a periplasmic space. This differentiates the outer membrane and the plasma membrane. |
| 13 | Outer membrane | The cell wall of the gram-positive is single-layered, so it does not contain the outer membrane. | The cell wall of the gram- negative is double layered. One is the plasma membrane, and another one is the outer membrane. |
| 14 | Lipid Content | The lipid content of the gram-positive bacteria is very low (1-4%) | The lipid content of the gram-negative bacteria is very high (11-22%). |
| 15 | Porin channels | The proteinaceous membrane channels called porins absent in the gram-positive bacteria. | The proteinaceous membrane channels present in the gram-negative bacteria because it contains the outer membrane. |
| 16 | Lipopolysaccharides | Lipopolysaccharides are absent in the layer of the plasma membrane. | Lipopolysaccharides are present in the layer of the outer membrane. |
| 17 | Mesosomes | Mesosomes are quite prominent in the gram-positives. | mesosomes are less prominent in the gram-negative. |
| 18 | Endospores | In the unfavorable stress condition, the gram-positive bacteria transform into endospores. | The gram-negative bacteria usually do not produce endospores. |
| 19 | Flagella | The basal body of the flagella in gram-positive bacteria contains two rings. | The basal body of the flagella in gram-negative bacteria contains four rings. |
| 20 | Toxins | Most of the gram-positive bacteria will produce exotoxins. | Most of the gram-negative bacteria produce endotoxins. |
| 21 | Antibiotic resistance | Gram-positive bacteria are less resistant to antibiotics | Gram-negative bacteria are mostly immune to antibiotics. |
| 22 | Antibiotic susceptibility | gram-positive cells show high sensitivity to penicillin and sulfonamides antibiotics. | gram-negative bacteria show low susceptible to next-generation penicillin and cephalosporins antibiotics. |
| Gram-positives show low susceptibility to aminoglycoside, chloramphenicol and tetracycline antibiotics. | The gram-negative bacteria show high susceptible to Aminoglycoside, chloramphenicol, and tetracycline antibiotics. | ||
| 23 | Sodium azide resistance | Highly resistant to sodium azide solution. | Less resistant to the sodium azide solution. |
| 24 | Lysozyme enzyme | Their cell wall is highly susceptible to degradation by lysozyme enzyme. | Their cell wall is less susceptible to the lysozyme enzyme |
| 25 | Dryness climate | Gram-positives have high tolerance to dryness. | Have less tolerance to dryness. |
| 26 | Magnetosomes | absent in the gram- positive bacteria | Some of the gram-negatives have magnetosomes |
| 27 | Pathogenic | Very few gram-positive bacteria are pathogenic to humans and animals. | Most of the gram-negative bacteria are pathogenic to humans and animals |
| 28 | Examples | Bacillus substilis, Streptococcus, Lactobacillus, Leuconostoc, Clostridium like species | E. coli, Rhizobium, Vibrio, Acetobacter, etc., |
- They possess capsules.
- Both have the covalently closed circular DNA as the genetic material.
- They both contain extra-chromosomal genetic material (plasmids).
- Both undergo binary fission as a mode of asexual reproduction.
- Both groups included the flagellated (motile) and non-flagellated (non-motile) forms.