Pod film capsule

Capsule capsule/?kæpsju?l/ CET6 TEM4 one star

N-count a capsule is a very small tube containing powdered or liquid medicine, which you swallow. Capsules (of charge)

The capsule is a mucous substance that is surrounded by some bacteria outside the cell wall, usually composed of sugars and polypeptides.

Pod Film (capsule)

Pod: Certain bacterial surface of the special structure, is located on the surface of the cell wall of a loose slime material, the composition of the pod is different from the various strains, mainly by the glucose and glucose aldehyde polymer, also contains peptides and lipids.

categoryPod or large capsule: the cell wall binds firmly, thickness ≥ 0.2 microns is called pod or large capsule. such as pneumococcal. Micro-pod: With cell wall binding firm, thickness <0.2 Micron is called a micro-pod membrane. such as the vi antigen of Salmonella typhimurium. Mucus layer (slime layer): loose adhesion to the cell surface, the boundary is not obvious and easy to be eluted called the mucus layer. Sugar calyx: The structure between the pod and the mucus layer is called the sugar calyx.Chemical Compositionpolysaccharide \ polypeptide \ Other substances polysaccharide: Most of the bacterial capsule is composed of polysaccharides. The molecular composition and configuration of polysaccharides are very complex and become the basis of serum credit type. For example, pneumococcal, according to the antigen of its capsular polysaccharide, at least can be divided into 85 serotypes. Polypeptide: A few bacterial pods are peptides, such as anthrax, Bacillus pestis, etc. The water content of the capsule was 90%~98%, and some bacteria had the pod membrane containing polysaccharide (monomer was D-glucose, D-glucose aldehyde, D-galactose, L-rat-li Sugar, l-fucoidan, etc.). The bacterium of anthrax contains polypeptide (monomer is D-glutamic acid). The pod membrane of the giant bacillus is composed of a network of polysaccharides, the gap is inlaid with D-glutamic polypeptide. Some capsules contain lipid or lipid protein complexes.4 Features①anti-engulfing effect: The pod membrane can effectively resist phagocytosis of host phagocytic cells because of its hydrophilicity and space occupying and barrier effect. Iiadhesion effect: capsular polysaccharide can make bacteria adhesion to each other, but also adhesion to tissue cells or inanimate objects surface, is an important factor that causes infection, has a capsule of S-type Streptococcus pneumoniae virulence is strong, to help the infection of Streptococcus pneumoniae human body; the bacterial pod membrane in the wastewater biological treatment has the biological adsorption effect, the organic matter in the waste water, Inorganic and colloidal adsorbed on the surface of the bacterium body. ③damage effect of anti-harmful substances: In the outermost layer of bacterial cells, the capsule is like armor which can effectively protect the bacteria from or less affected by a variety of sterilization, antibacterial substances, such as lysozyme, complement and so on. ④anti-drying effect: Capsule polysaccharide is a highly hydrated molecule with water content above 95%, which helps bacteria resist the threat of dryness to survival. ⑤ When nutrition is lacking, the capsule can be used as acarbon sources and energy, some capsules can also be used as nitrogen source. Application: ① antigen of different serum type ② differentiate bacterial ③ preparation vaccine bacteria are the most widely distributed organisms in nature and the largest number of individuals, and are the main participants in the natural material cycle. Bacteria are mainly composed of cell wall, cell membrane, cytoplasm, nuclear body and other parts, and some bacteria also have pods, such as the skin, fungus, hair, such as umbrella and other special structures. Many bacteria are also covered with a layer of polysaccharides, the boundary is obviously called the capsule (capsule), such as pneumococcal, the boundary is not obvious called the mucus layer (slime layers), such as Staphylococci. Pod membrane is important for the survival of bacteria, bacteria can not only use the capsule to resist adverse environment, protect themselves from white cells, and selectively adhere to the surface of specific cells, showing the target cell specificity attack ability. For example, Salmonella typhimurium can invade intestinal lymphoid tissue in a sexual manner. The filaments of bacterial pods can also store the digestive enzymes secreted by bacteria for the purpose of attacking target cells.

Pod film capsule