yeast, any of about 1,500 species of single-celled fungi, most of which are in the phylum Ascomycota, only a few being Basidiomycota. Yeasts are found worldwide in soils and on plant surfaces and are especially abundant in sugary mediums such as flower nectar and fruits.

Where is yeast most commonly found?

Yeast are widely dispersed in nature with a wide variety of habitats. They are commonly found on plant leaves, flowers, and fruits, as well as in soil. Yeast are also found on the surface of the skin and in the intestinal tracts of warm-blooded animals, where they may live symbiotically or as parasites.

How is yeast made?

The baker's yeast is commercially produced on a nutrient source which is rich in sugar (usually molasses: by product of the sugar refining). The fermentation is conducted in large tanks. Once the yeast fills the tank, it is harvested by centrifugation, giving an off-white liquid known as cream yeast.