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 |