Lipopolysaccharides are the major constituents of the cell walls of gram-negative bacteria, consisting of a lipid part, lipid A, and two polysaccharide parts. They are highly immunogenic, and stimulate the production of endogenous pyrogen interleukin-1 (IL-1) and tumor necrosis factor (TNF). It is the lipid A that exerts the toxic effects of endotoxin, such as fever, sepsis, etc. During growth, bacteria shed outer membrane fragments containing LPS. Endotoxins are also liberated when bacteria die.
Lipopolysaccharides are extracted from Pseudomonas aeruginosa strains grown on branched-chain carbon sources and then chemically characterized. Lipopolysaccharides are essential for the survival of Gram-negative bacteria, providing a permeation barrier for harmful substances. In addition, LPS play an important role in a number of recognition processes. Whereas the advance in development of antibiotics has resulted in effective treatment of infections by Gram-positive bacteria, infections by Gram-negative bacteria in patients with a weakened immune system are becoming an increasing problem. The LPS of Gram-negative bacteria are potent stimulators of the immune system, inducing acute proinflammatory responses and septic shock (also known as gram-negative sepsis or endotoxic shock). Gram-negative bacteria most responsible for septic shock are the common symbiotic residents of the gastrointestinal tract, including Escherichia coli, Klebsiella-Enterobacteriaceae-Serratia and Pseudomonas aeruginosa.
Lipopolysaccharides are a major constituent of the cell walls of gram-negative bacteria, and are recognized as the active component of gram-negative bacterial endotoxins. Lipopolysaccharide is a complex of lipid and carbohydrate derived from the cell wall of smooth strains of gram negative bacteria. Lipopolysaccharides occur naturally in the environment wherever gram negative bacteria are found. The monomer molecular weight of these lipopolysaccharides is approximately 10,000 daltons, however, in solution they usually exist as micelles with molecular weights ranging from hundreds of thousands to millions. The bacteria from which the products were derived have been removed during the course of purification. The solvent in which these products are packaged is water and, therefore, the lipopolysaccharide in each container represents 100% of the mass.