Yeast Culture Collections, Strain Maintenance and Propagation

Abstract

Microbial culture collections (including yeast cultures) focus at collecting, maintaining and distributing microbial strains amongst microbiologists, brewers and distillers. They are means of preserving microbial diversity. The importance of selecting optimal yeast strains for research and/or industrial applications is often underestimated. Yeast cultures stored in a yeast collection are usually (but not always) purified cultures. Today, it is possible for brewers, both home brewers and professionals, to obtain yeast strains from culture collections and have then been shipped worldwide. Prior to yeast propagation, it is imperative that no change in the character of the yeast strain occurs. Today, many breweries store their strains (or contract store them) at −70 °C. The yeast propagation process is not fully understood. Brewer’s yeast cultures do not live forever and must be replaced with fresh yeast on a regular basis. Yeast propagation was pioneered with lager strains in the late nineteenth century. However, the value of regular ale strain propagation is still questioned. With the advent of high-gravity wort fermentation, its use in ale propagation procedures (as well as lager) has become an accepted brewing procedure.