Genetic Improvement of Baker's Yeasts

Yeasts have been used for many thousands of years to produce leavened bread. Nowadays the production of baker's yeast biomass represents a highly competitive multi-billion dollar global industry. The environmental conditions that prevail during manufacture and application of baker's yeasts, coupled with the sheer variety of bread making processes and recipes used around the world, place considerable demands on yeasts. These demands translate into technological and economic challenges for producers of baker's yeasts. One way to meet these challenges is to improve the physiological attributes of yeasts so that they are better suited to the complex requirements of the modem baking industry. Improvement or modification of yeast performance can be achieved to some extent by modifying the parameters of their growth and downstream processing during production. However, the potential of a yeast strain's performance is dictated in the first place, by the genetic makeup of that strain. The emerging knowledge of yeast genomics and proteomics promises to deliver important strategies for improving the genetic potential of strains of baker's yeasts. Genetic modification of baker's yeast can be achieved by classical or molecular procedures, or a combination of both approaches. However, given the general negativity surrounding GMO's, we contend that classical strategies remain the most practical approach to developing strains for commercial applications. Nevertheless, genomics and molecular techniques remain important for determining key genes, pathways and associated physiological functions that need to be enhanced in novel strains of baker's yeast.