Microbiological, physiological, identification, and typing methods

1 Differences in top- and bottom-fermenting brewing yeast strains 

Large cell formations or large star-like clusters are not formed by aU Saccharomyces cerevisiae strains, however. Most Saccharomyces cerevisiae strains used to produce altbier and kolsch as well as certain ale strains form only very small cell clusters consisting of one to four cells. These are often very difficult to differentiate from Saccharomyces pastorianus lager strains, especially when they appear close together. Additional characteristics differentiating BF and TF yeast are as follows  

Detailed descriptions of these differences and the related methods are described in several pnblications and overviews (Back, 1994 Dufour, Verstrepen, Derdehnckx, 2003 Hutzler, 2009 Priest CampeU, 2003 Rocken Marg, 1983). 

Some promising new methods are not provided in this table however, they are discussed in Section 5.2.4 below. The variety of identification and differentiation methods is extensive only a few are implemented in the routine analysis conducted in commercial laboratories, and even fewer in the microbiology laboratories of breweries. A list of some of the established and reliable routine methods for rapid yeast identification is found in Section 5.2.3. Which method is applied in brewery laboratories or combined with the established routine methods depends on the practicability and the degree of aceeptance for new techniques, which require special training and knowledge of yeast handling. 

3 Seiection of successful standard and recently introduced methods 

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