What is the role of a capsule in bacteria?

Cell vesicles are a very large structure of prokaryotes such as bacterial cells. It is a layer of polysaccharide located outside the outer membrane of bacterial cells and is therefore considered part of the outer shell of bacterial cells. It is a well organized layer, not easy to wash away, it may be the cause of various diseases

Capsules found in gram-negative and gram-positive bacteria should not be confused with the second lipid membrane (or bacterial outer membrane) containing lipopolysaccharide and lipoprotein, but only in Gram-negative bacteria. . If the amorphous viscous secretion (constituting the capsule) diffuses into the surrounding medium and retains loose secreted secretions, it is called the mucous layer.

The bacterial sac has a semi-raised border along the contours of the cell. When dyed, the capsules do not contain Indian ink. The slime layer is a matrix without bumps that can be easily deformed and can not eliminate Indian inks. Biofilms are composed of many cells and their external barriers. The main function of the capsule and mucous layer is protection and adhesion.

However, it can be composed of other materials (eg, polysaccharide (D-glutamic acid) is also anthrax peptidoglycan or muramic acid in bacterial capsule of Escherichia coli). Most stains are not attached to capsules, so it is difficult to dye with standard stains, bacteria and their backgrounds are darker than capsules and not dyed for observation under a microscope. In black, the capsule is still pale or colorless and appears as a ring or halo around the cell.

Capsules are considered to be virulence factors, as bacteria enhance the ability to cause disease (eg, prevent phagocytosis). Capsules protect cells from the phagocytosis of eukaryotic cells such as macrophages

Capsule specific antibodies may be required for phagocytosis. The capsule contains water to protect the bacteria from drying. They also eliminate the most hydrophobic toxic substances such as bacterial viruses and detergents.

Immunity to certain types of capsules does not result in immunity to other types. Capsules help cells adhere to the surface.

Capsules: In many of the bacteria there are sticky capsules on the outside of the cell wall. It consists of polysaccharides and also contains nitrogen-containing substances (amino acids). The mucus layer thickens and is called a capsule. Bacteria that form capsules are called encapsulated bacteria or toxic bacteria. Capsules are usually present in the form of parasites such as Bacillus, Anthracite, Pneumococcus, Mycobacterium tuberculosis. Cytoplasm: Cytoplasm is a complex aqueous or semi-fluid substance (matrix). This substance consists of vitamins, salts, enzymes, carbohydrates, soluble proteins, coenzymes, lipids, minerals and nucleic acids. The organic matter exists in a colloidal state. Because of the large number of ribosomes, the cytoplasm is granular.

Many bacteria produce capsules consisting of various selected molecules, including several complex carbohydrates, which may include polypeptides and cellulose, outside the walls of cell wall proteins. Bacteria with this outer shell are called Gram negative bacteria because they do not absorb specific dyes known as Gram stain. Bacteria that lack external capsules absorb dyes called gram positive bacteria. Gram staining is a basic tool for identifying bacteria. Escherichia coli in human large intestine is gram negative

According to "Mims Medical Microbiology" there are three basic bacterial shapes. Circular bacteria are called cocci (singular: cocci), cylindrical capsule bacteria as bacilli (singular: Bacillus), spirochetes and spirochetes are suitably called spirilla (singular: spiroheter). Cocci can also be combined with each other in different configurations: a combination of 2 or 2 streptococci; linear or streptococci; and 1 cluster or staphylococci. Bacterial shape and composition are usually reflected in that name. For example, Lactobacillus lactis is a bacterium, and Streptococcus pneumonia causing pneumonia is a sterile strand.