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6.2.2.2.2. Bacterial wall

Bacterial wall

It is a rigid shell that is mainly composed of peptidoglycans (murein). It is located between the plasma membrane and the bacterial capsule, if it exists. It is between 50 and 100 Å thick.

According to the Gram stain, two types of bacterial wall are distinguished.

  • The Gram positive wall is monostratified and is made up of a thick basal layer of peptidoglycans (murein), to which proteinspolysaccharides and teichoic acids are associated.
  • The Gram negative wall is bi-stratified, with a thin basal layer of peptidoglycans, on which there is a double lipid layer that contains a large number of proteins, most with enzymatic activity, and glycolipids. This layer is called the outer membrane.

The bacterial wall is responsible for maintaining the shape of the bacteria and protecting it against changes in the osmotic pressure of the medium.

Penicillin

The penicillin is an antibiotic which prevents the formation of the bacterial wall. As the bacterial cell wall is a rigid envelope whose function is to maintain the shape of the cell against changes in osmotic pressure and to regulate the passage of ions, the alteration of the bacterial wall causes the death of the cell. since it loses the function of maintaining its shape in the face of osmotic changes.