Yeast Suspension Culture

Yeasts are important production organisms for many different biotechnological products, both metabolites and recombinant proteins. The main product classes are primary metabolites such as bioethanol, secondary metabolites such as vitamins or heterologous terpenes, and recombinant enzymes and biopharmaceuticals. Besides the classical yeast Saccharomyces cerevisiae several non-conventional yeasts have gained importance in biotechnology. Suspension culture at large scale is state of the art for yeast production processes, and in fact baker's yeast production has been one driver for the development of large scale submerged cultivation of microorganisms. Two developments have created an increasing interest in using yeast as production platform: the long-term demand to produce fuels and chemicals from renewable feedstocks, and the cost pressure on biopharmaceuticals, which makes the use of cheaper microbial production processes attractive. Focusing mainly on recombinant protein production this chapter highlights the choice of the right production strain, the set up of an expression system, and the design of a production process. Technical challenges, such as minimizing of oxygen demand and heat generation, and regulatory aspects are also discussed.