Xanthomonas campestris is bacterial species that causes a variety of plant diseases. Available from the NCPPB and other international culture collections such as ICMP, ATCC, and LMG in a purified form, it is used in the commercial production of a high-molecular-weight polysaccharide - xanthan gum - that is an efficient viscosifier of water and that has many important uses, especially in the food industry. It causes spots on the infected plant.