Under certain conditions, bacteria can form biofilm, and bacteria wrapped by biofilm are called biofilm bacteria. Bacteria adapt to the natural environment and are conducive to survival, which is a life phenomenon. It is made up of microorganisms and their secretions. No matter its morphological structure, physiological and biochemical characteristics, pathogenicity or sensitivity to environmental factors, Myxomycetes are significantly different from planktonic bacteria, especially with strong resistance to antibiotics and host immune system, which leads to serious clinical problems and the recurrence of many chronic and refractory infectious diseases. It is difficult to remove the bacterial biofilm attached to various medical instruments and catheters, resulting in a large number of iatrogenic infections.
The formation of capsules is closely related to environmental conditions. Generally, the capsule is easy to form in animals or media containing serum or sugar, but it is easy to disappear in ordinary media or continuous passage. Function: ① Anti-phagocytosis: It can effectively resist the phagocytosis of host phagocytes. ② Adhesion: Capsular polysaccharide can make bacteria adhere to each other, or to the surface of tissue cells or inanimate objects, which is an important factor causing infection. ③ Anti-injury effect of harmful substances: Capsule is located in the outermost layer of bacterial cells, just like armor, which can effectively protect bacteria from or be less damaged by various bactericidal and bacteriostatic substances. ④ Anti-drying effect: Capsular polysaccharide is a highly hydrated molecule, which can help bacteria resist the threat of drying to survival. ⑤ Capsule can be used as carbon source and energy source when nutrition is deficient, and some capsules can also be used as nitrogen source.