BIOC17H3 Lecture Notes - Lecture 11: Extracellular Polymeric Substance, Glycocalyx, Biofilm
Document Summary
In some bacteria they have an extra layer surrounding a bacterium. It can either be viscous substance or extracellular polymeric substance: polysaccharide called extracellular polymeric substance which is a layer of material which is outside the cell wall. It serves as a barrier to protect cells from external environmental stress such as extreme temperature. In other bacteria they have a viscous substance. In these surrounding layers, some also have poly d-glutamic acid. These extra layers are genetically determined, but it can be altered through nutrient or physiological conditions. Capsule: viscous substance or extracellular polymeric substance that is discrete, well organized and not easily removed, tightly bound to the cell, protects pathogenic bacteria from phagocytosis by the cell to the host, contribute to bacteria virulence. Slime layer: amorphous, diffuse, unorganized and easily removed, not tightly bound to the cell, protects cell against dehydration and loss of nutrients. Biofilm- polymeric matrix in which microbes of the same or difference specie embedded.
