A fungus that forms single cells that reproduce by budding or binary fission. They are exploited commercially as biocatalysts in biotechnological processes such as in the production of alcoholic beverages wine and beer, as well as for the production of bioethanol, which is used as a motor fuel or petroleum additive. Fungi have the ability to convert sugars to alcohol through the process of fermentation. They are also used in single-cell protein production as well as in baking. They are also a dietary source of protein and vitamin B. There are many genera and important yeasts used in biotechnological processes include Saccharomyces, Kluyveromyces, and Candida.