Xanthan gum, a microbial polysaccharide produced by *Xanthomonas campestris*, has a cellulose backbone of β-(1-4)-linked glucose units with a trisaccharide side chain of mannose-glucuronic acid-mannose attached to every other glucose unit. Some terminal mannose units are pyruvated, and some internal mannose units are acetylated. Due to its unique rheology and gelling properties, it is widely used as a food additive, thickener, and stabilizer in the food and petroleum industries.