a term referring either to a collection of yeast cultures (culture collection) or to an entity that holds a culture collection. A yeast bank can be held at a university, at a private company, or by individuals. Yeast banks exist throughout the world. The yeast may be stored for scientific purposes, commercial applications, or food and agricultural applications.

The yeast cultures stored in a yeast bank are usually purified yeast cultures. Yeast was first purified by Emil Christian Hansen in 1883. See hansen, emil christian. Once yeast was in pure form, laboratories started keeping a bank of strains and supplying them to breweries. In 1885, the Scientific Station for Brewing in Munich reported distributing 107 cultures to breweries. Today, it is possible for brewers, both amateur and professionals, to order yeast from yeast banks and have it shipped worldwide in various forms.

Yeast can be stored in a yeast bank in a number of ways. One of the earliest methods, still in use today, is to store yeast on agar plates or slants (slopes); these are then subcultured every 3–6 months to maintain viability. This method is not the best for long-term storage of the overall yeast bank, because yeast will mutate over time. Some yeast banks store their yeast in freeze-dried format, but this is less common because of reports of low viability, flocculation changes, and mutation. The most common way yeast is stored in a yeast bank is to deep freeze the cultures at either –80°C (ultrafreezers) or –196°C (liquid nitrogen).