Bacteria Cell Wall Types: 7 Important Facts You Should Know


In this article, we get to know about Bacteria Cell Wall Types, structure, composition and functions.

One thing to keep in mind is that not all bacteria have cell walls. Having said that, it is also crucial to remember that the majority of bacteria (about 90%) have cell walls, and these cell walls are normally either gram – positive or gram negative. In the lab, the 2 different cell wall types can be distinguished using a differential stain called the Gram stain.

What is bacteria cell wall?

Unicellular (single-celled), prokaryotic (without a clearly defined nucleus and membrane-bound organelles), microscopic organisms known as bacteria are found practically everywhere on Earth, even in strange and hostile environments.

Ex: 1. Bacteria are of various shapes and sizes such as spheres, rods, chains, spirals, etc. Other classification criteria for bacteria include some of those listed below:

  • Shape or morphology
  • Oxygen requirements
  • Mode of nutrition
  • Environmental factors like temperature, salt, and pH requirement
  • Staining behaviour

2. Despite several differences, most bacteria share similarities in their cellular structure. A typical bacterium has important structural elements, including as:

3. Cellular components include the cell wall, cell membrane, cytoplasm, ribosomes, flagella, and pili. A bacterial cell wall is an exterior, rigid layer that gives the cell’s membrane greater strength. Carbohydrates make up the majority of the complicated bacterial cell wall composition.

bacteria cell wall types
The structure of peptidoglycan from Wikipedia

Composition

The bacterial cell wall differs from the cell walls of all other organisms due to the peptidoglycan, which is located immediately well outside the cell membrane. N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) groups alternated in equal amounts along the polysaccharide backbone of peptidoglycan.

Function of bacterial cell wall

During bacterial growth, the cell wall performs a number of functions, including defending against internal turgor pressure and ensuring the integrity and shape of the bacterial cell. Additionally, it must continue to be adaptable to allow for the remodelling needed for cell growth and division.

  • The bacterial cell wall’s main function is to give the cell overall strength. 
  • The cell wall shields it against osmotic lysis. The cell is constantly changing environments, and because water may pass freely through the cell wall and membrane, an osmotic imbalance could lead to osmotic lysis of the cell.
  • The cell wall aids in blocking some potentially hazardous chemicals.
  • The ability of bacterial cells to cause ailment, or their pathogenicity, is influenced by their cell walls.

What are the types of bacteria cell wall?

In addition to acting as a layer of protection, the bacterial cell wall plays a crucial role in classifying bacteria into the gram-negative and gram-positive categories. Compared to gram-negative bacteria, gram-positive bacteria have chemical structures in their cell walls that are simpler.

bacteria cell wall types
types of bacteria cell wall from pixabay

Ex: There are three primary components outside the peptidoglycan layer: the lipoprotein layer, the outside membrane, and the lipopolysaccharides.

Lipoprotein layer: Special lipoproteins known as Braun’s lipoproteins make up the majority of this stratum. These tiny lipoproteins are bonded covalently to the peptidoglycan layer below. By the hydrophobic end of the outer membrane, they are enmeshed within it.

Outer membrane: This membrane is composed of two layers. The composition of the outside part is different from the inner part, which is similar to the cell membrane. Porins and outer membrane proteins are among the proteins found in the outer membrane.

Lipopolysaccharides: Complex molecules are lipopolysaccharides. They aid in the gram negative bacteria’s adhesion since they have an adhesive nature. The three main elements of this layer are lipid A, Core oligosaccharide, and O polysaccharide.

What is gram-negative bacteria cell wall?

Compared to gram positive cell walls, gram-negative cell walls are more complicated. Additionally, the peptidoglycan content of the gram negative cell wall is significantly lower. Peptidoglycan is only found in two levels slightly outside the gram-negative cell wall.

What is gram positive bacteria cell wall?

Gram-positive cell walls are more homogeneous and thicker than gram-negative cell walls, measuring between 15 and 80 nm. This cell wall is made up of several layers of peptidoglycan in large quantities. In gram-positive cell walls, peptididoglycan makes up between 40 and 80 percent of the dry weight.

Ex: Gram-positive bacteria have teichoic acid and teichuronic acid in their cell walls. In addition to these acids, gram-positive cell walls also include neutral sugars and acidic sugars that are present as parts of polysaccharides.

Teichoic acids: Teichoic acids are ribitol and glycerol-containing polymers of polyribitol phosphate and polyglycerol phosphate. These polymers may have side chains or internal amino acid or sugar replacements. There are two different kinds of teichoic acids: lipoteichoic acid and wall teichoic acid. Teichoic acids form a covalent connection with the peptidoglycan chain.

Teichuronic acids: Teichuronic acid is made up of repeating sugar acid building blocks. When the cell’s phosphate supply is insufficient, they are produced as teichoic acid replacements.

Unusual and Wall-less Bacteria

Mycoplasma and L-form bacteria are a couple of examples of bacteria that don’t have cell walls. Mycoplasma is a significant cause of sickness in animals, and antibiotic therapies that target cell wall formation do not work against it.

bacteria cell wall types
Structure of Mycoplasma from pixabay

Conclusion

In the above article, we studied about bacterial cell wall structure and characteristics. Gram positive and gram negative bacterial cell wall and some unusual bacteria.

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