Bacterium CapsuleIntroduction Bacterium capsule is a protective structure surrounding some bacterial. It is attached to the cell wall through phospholipids. It promotes bacteria adhesion to surfaces. It also acts as a permeability barrier and as a defense mechanism against phagocytosis and desiccation (Barton, 2005).The bacterium capsule gets through a series of external openings (spiracles) which acts as a muscular valve. Then it gets through the internal respiratory system, a densely networked array (the tracheae). This network of transverse and longitudinal tracheae in the menduca larva equalizes pressure throughout the system. Since it is a layer that lies outside the cell wall of bacteria, it is well organized and it is not easily washed off. This makes it diffuse through the trachea system. Its slime layer diffuses into the surrounding medium as a loose undemarcated secretion. The capsule usually consists of polysaccharides and is water soluble thus dissolves in the moisturize tracheae through the spiracles. Thus they are difficult to stain using standard stains as they do not adhere to the capsule (Chapman, 2004). Since the capsule remains pale and colorless, it is difficult to be detected and appears as a ring around the cell. The tracheae are water filled as they consist of permeable membrane of the surrounding tissues which make the capsule soluble since it is water soluble. The water level however retracts due to the increase in concentration of lactic acid found in the muscle cells during the respiration system. The capsule contains external chemical sensors which therefore detects the concentration of lactic acid, lowering the water potential in the system which is then drawn back into the cells through osmosis process while the capsule gets closer to the muscle cells. While the diffusion pathway is reduced as a result, the capsule can then be transferred more easily through the tracheal. The bacterium capsule is typically stimulated for easy movement throughout the system. The neuro-secretory cells made in the cell body consist of prothoracic gland which acts as circulatory system storage gland and hormonal control of insect molting (Ulrich, 2009).The capsule is said to be a virulence factor as it enhances the ability of a bacteria to cause harm in the trachea system. Since the capsule is equipped with windows and powerful lights, it protects cells from engulfing by eukaryotic cells such as macrophages. As the capsule moves through the trachea it will detect bacteria present in the moisture trachea and prevent against desiccation. Capsule will also detect bacteria viruses and most hydrophobic toxic materials such as detergents present in the tracheae with its powerful lights and widows. The capsule will also impair with its own antigencity as it moves through the tracheae. The capsule will also detect the respiratory surfaces and helps the respiratory cells adhere to the surfaces (Barton, 2005).Conclusion The capsule passes through the trachea system from the spiracles to the tissues, then to the mitochondria. Then it moves through a solution in the cytoplasm where tissue diffusion takes place. With the widows, powerful lights and external chemical sensors it is equipped with, it will detect eukaryotic cells (macrophages), bacteria viruses and hydrophobic toxic materials such as detergents present in the respiratory surfaces. It will then protect the respiratory gases from such toxic materials and bacterial. Since the capsule is water soluble, it will then diffuse in the respiratory gases through osmosis then out through the spiracles. This will take few minutes, the same period as the respiratory gases takes. Reference Barton, L. (2005). Structural and functional relationships in prokaryotes. New York: Springer.Chapman, R. F. (2004). The insects: Structure and function. Cambridge [u.a.: Cambridge Univ. Press.Ulrich, M. (2009). Bacterial polysaccharides: Current innovations and future trends. Norfolk, UK: Caister Academic Press.