Difference Between Gram Positive and Gram Negative Cell Wall
Last Updated :
23 Mar, 2023
Cell walls of gram-positive bacteria are thick and predominantly made of peptidoglycan. In the cell wall of gram-positive bacteria, long chains of sugars and amino acids make up the complex chemical known as peptidoglycan, which supports the bacterial cell wall structurally. Whereas, Gram-negative bacteria have a multilayered cell wall that is a complex construction. The outer membrane, of Gram-negative bacteria, is composed of proteins and lipopolysaccharides (LPS), which is the outermost layer.
Feature of Gram-Positive Cell Wall
- Thick peptidoglycan layer: Outside of the cytoplasmic membrane, gram-positive bacteria have a thick peptidoglycan layer. The cell’s structural support and defense are provided by this peptidoglycan layer.
- Teichoic acids are polymers made of glycerol, ribitol, or glycol that are covalently attached to the peptidoglycan layer in gram-positive bacteria. Teichoic acids are involved in the preservation of cell structure, cell division, and antibiotic resistance.
- Outside of the peptidoglycan layer, Gram-positive bacteria do not possess an outer membrane, in contrast to Gram-negative bacteria. Instead, a layer of proteins and lipids covers the peptidoglycan layer.
- Susceptibility to specific antibiotics: Due to the thick peptidoglycan coating, Gram-positive bacteria are vulnerable to drugs like penicillin and cephalosporins that attack this structure.
Feature of Gram-Negative Cell Wall
Some significant aspects of the Gram-negative cell wall, which is a distinguishing trait of some species of bacteria, include:
- Thin peptidoglycan layer: In comparison to Gram-positive bacteria, gram-negative bacteria have a thinner peptidoglycan layer. The periplasmic space, which is the area between the outer and inner membranes, is where the peptidoglycan layer is found.
- Lipopolysaccharides (LPS) and proteins make up the outer membrane of gram-negative bacteria. This outer membrane serves as a defense against harmful environmental elements and hinders the entry of antimicrobial agents into the bacterial cell.
- Lipopolysaccharides (LPS): Lipid A, core polysaccharide, and O-antigen make up the LPS layer of the outer membrane. The host immune system recognizes lipid A as an endotoxin and it might result in fever, inflammation, and other infection-related symptoms.
- Porins: The outer membrane of Gram-negative bacteria contains porins, which are proteins that form channels that allow the flow of tiny molecules, such as nutrients, into the cell.
Difference Between Gram-Positive and Gram-Negative Cell Walls
Parameters
|
Gram-Positive Cell Wall
|
Gram-Negative Cell Wall
|
Thickness of the peptidoglycan layer |
It is too much thick |
It is thin. |
Availability of outer membrane |
The outer membrane does not present. |
Here outer membrane is present. |
Presence of Lipid content |
Here teichoic acid and lipoteichoic acid are present. |
Here lipopolysaccharide (LPS), lipoprotein, and phospholipids are present. |
Presence of Porin proteins |
It is not present. |
It is present in the outer membrane. |
Susceptibility to antibiotics |
This is more susceptible due to the thicker peptidoglycan layer |
This is less susceptible because of the outer membrane and efflux pumps. |
Toxicity |
Here toxicity is less |
Here toxicity is High |
Outer membrane components |
Does not have any outer membrane |
These are some components that are present in the outer membranes such as Lipopolysaccharide (LPS), lipoprotein, and phospholipids |
Presence of periplasmic space |
very small or negligible periplasmic space is available |
Large periplasmic space is available |
Ability to form endospores |
There are only some species can form endospores because it is highly resistant structures. |
Here can not be formed. |
Ability to lyse in a hypertonic environment |
It is susceptible to lysis |
It is resistant to lysis |
Presence of flagella |
It may have peritrichous or polar flagella |
It may also have peritrichous or polar flagella |
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