These mushrooms belong to the kingdom Fungi. This kingdom includes yeasts, molds, and many familiar mushrooms. The cell walls of fungal cells are composed of glucans and chitin, whereas plant cell walls contain cellulose. The role fungi play in the environment is in the decomposition of organic matter and in nutrient exchange. Additionally, fungi are used in the leavening of bread, the fermentation of foods and drinks, the production of antibiotics, and in detergents. Fungi were once considered members of the Plantae kingdom because of their similar lifestyles, but current genetic research suggests that fungi are actually more closely related to animals than to plants.