Fermentation fungi, specifically yeasts, are microscopic single-celled organisms that are used in the production of alcoholic beverages and breads. Yeasts are able to convert sugars into carbon dioxide and alcohol through the process of fermentation. They are also used in the production of certain cheeses, as well as in the production of some antibiotics. Yeasts are an essential part of the food industry, and have been used for centuries to produce a variety of products.