lipopolysaccharide biosynthetic pathway LPS biosynthetic pathway PW:0000249 Those metabolic reactions involved in the biosynthesis of lipopolysaccharides, also known as lipoglycans, found in the outer membranes of Gram-negative bacteria. They are large molecules consisting of a lipid and a polysaccharide joined by a covalent bond. In host cells they act as endotoxins which are recognized by members of the Toll-like receptors to elicit strong immune responses. lipoglycan biosynthetic pathway lipopolysaccharide biosynthetic process pathway bacterial polysaccharide metabolic pathway