Brewing yeast genetics

Brewing yeasts are differentiated into ale and lager types. The former are considered older in evolutionary terms and are classified as S. cerevisiae. They express considerable genetic variability (Pedersen, 1985, 1986a, 1986b, 1994). Lager strains are 

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Andersen, T. H., Hoffmann, L., Grifone, R., Nilsson-TUlgren, T., KieUand-Brandt, M. C. (2000). Brewing yeast genetics. Numberg Hans Carl Fachverlag. 

The enormous potential of recombinant DNA technology will undoubtedly be exploited in the near future for the genetic manipulation of brewing yeast strains. 

It is common practice to maintain yeast cultures used for genetic analysis in dried form using silica gel as a desiccant [35]. This procedure which is far simpler than either freeze-drying or storing under liquid nitrogen has apparently not been examined as a means of maintaining brewing yeast cultures. 

For the production of AFB, special yeasts that produce lower amounts of ethanol or no ethanol at all can be used as well. This can be achieved either by selection of proper yeast strains that are not able to ferment maltose and maltotriose (e.g. Saccharomy-codes ludwigii) or by intentional modification of brewing yeast by random mutation or genetic engineering (Branyik, Silva, et al 2012 Burberg Zamkow, 2009). 

Nevoigt, E., Pilger, R., Mast-Gerlach, E., Schmidt, U., Freihammer, S., Eschenbrenner, M., et al. (2002). Genetic engineering of brewing yeast to reduce the content of ethanol in beer. FEMS Yeast Research, 2, 225-232. 

Libkind, D., Hittinger, C. T., Valerio, E., Gon9alves, C., Dover, J., Johnston, M., et al. (2011). Microbe domestication and the identification of the wild genetic stock of lager-brewing yeast. Proceedings of the National Academy of Sciences, 108(35), 14539 44. 

Young, T. W. (1981). The genetic manipulation of killer factor into brewing yeast. Journal of the Institute of Brewing, 87, 292-295. 

The fermentation in these big vessels (max 3—5 brews) is normally performed pressureless, but several investigations have been made on fermentation under pressure and using somewhat higher temperatures in order to reduce the time needed still further. Some brewers agree with the statement that no yeast yet known can tolerate this extra stress and at the same time ferment a beet of equivalent excellent quaUty, but new selected yeast strains (genetic engineering) in the future may be better suited to these conditions. 

Brew, C. T. and Huffaker, T. C. The yeast ubiquitin protease, Ubp3p, promotes protein stability, Genetics, 2002, 162, 1079-89. 

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