The main components of bacterial cell wall

I believe that people who do not have relevant biological theoretical knowledge do not know much about the main components of bacterial cell walls. From a biological point of view, only by understanding the main components of bacterial cell walls can we find ways to fundamentally control this type of bacteria. Therefore, bacterial culture in the laboratory is also to observe the existence form of bacteria in the environment. Therefore, it is also very important for everyone to understand the relevant knowledge about the main components of bacterial cell walls.

The main component of bacterial cell wall is peptidoglycan, also known as sticky peptide. The mechanical strength of the cell wall depends on the presence of peptidoglycan. The ability to synthesize peptidoglycan is unique to prokaryotes. Peptidoglycan is a polysaccharide scaffold composed of two amino sugars, n-acetylglucosamine and n-acetylcytolic acid, connected and arranged at intervals by β-1.4 glycosidic bonds. Tetrapeptide side chains are connected to the n-acetylmuramic acid molecule, and the peptide chains are linked by peptide bridges or peptide chains to form a network structure with strong mechanical properties. The peptidoglycan scaffold of the cell walls of various bacteria is the same, but the composition of the tetrapeptide side chains and their connection method vary with the bacterial species.

Depending on the structure and chemical composition of bacterial cell walls, they can be divided into G+ bacteria (i.e. Gram-positive bacteria) and G- bacteria (i.e. Gram-negative bacteria). The cell wall of G+ bacteria is thicker (20-80nm), but its chemical composition is relatively simple, containing only 90% peptidoglycan and 10% teichoic acid; the cell wall of G- bacteria is thinner (10-15nm), but has a multi-layer structure (peptidoglycan and lipopolysaccharide layers, etc.), and its chemical composition contains not only peptidoglycan, but also a certain amount of lipids and proteins. In addition, the surface structures of the two are significantly different.

Proteins: G-bacterial cell walls contain more proteins, mainly outer membrane proteins, lipoproteins, and proteins embedded in lipopolysaccharide and phospholipid layers. There are also periplasmic proteins present in the periplasmic space (including various proteins responsible for solute transport, various hydrolases and certain synthetases). There are also proteins in the cell walls of G-bacteria, but in smaller quantities.