Molecular Mechanisms Involved in Yeast Fitness for Ethanol Production

Ethanol generated through bagasse and other waste is called second-generation ethanol. This biomass is a much more complex raw material that needs some other treatments before fermentation. A pretreatment is necessary for making carbohydrates more readily available for hydrolysis, which is responsible for Abstract Saccharomyces cerevisiae is well adapted to alcoholic fermentation. In this yeast, fermentation predominates over respiration at high glucose concentrations even under the presence of oxygen. Besides the solid fundamental knowledge base in system biology and in yeast metabolic pathways, this microorganism offers many favorable bioprocessing traits which allow robustness under industrial conditions, such as a. Genetic accessibility b. High tolerance to fermentative stresses -high temperatures, high ethanol and sugar concentrations, low pH c. Ideal physiology features (larger cell size, non-pathogenic, short generation time and ability to grow in a highly reproducible and genetically stable way with poor nutrient requirements). In this chapter, we will review the sugar and ethanol metabolism regulation as well as highlight the main molecular mechanism contributors to yeast multiple stress tolerance during fermentation. Furthermore, we will also discuss the future direction of genome and metabolic engineering of yeasts for ethanol production.