Xanthan Gum is a polysaccharide secreted by the bacterium Xanthomonas campestris. It is produced by the fermentation of glucose, sucrose, or lactose. After a fermentation period, the polysaccharide is precipitated from a growth medium with isopropyl alcohol, dried, and ground into a fine powder. Lastly, it is added to a liquid medium to form the gum. Xanthan Gum is used as a food additive and rheology modifier which is commonly used as a food thickening agent in salad dressings.