Waste toWealth: The Importance of Yeasts in Sustainable Bioethanol Production from Lignocellulosic Biomass

Climate change and global warming are two of the world’s most pressing environmental concerns. Bioethanol is considered as an alternative and renewable energy to reduce the usage of fossil fuels due to its environmental-friendly properties. In this chapter, we emphasize on the development of superior yeast strains for the production of bioethanol from lignocellulosic biomass. For instance, the substitution of a threonine at the position of 255 to alanine in ubiquitin ligase Rsp5 could increase the resistance of Saccharomyces cerevisiae cells to the fermentation inhibitor acetic acid. Additionally, the development of several S. cerevisiae strains that exhibitedmultiple stress tolerance against high temperature, high ethanol concentration, and a combination of fermentation inhibitors was also discussed. The pentose-utilizing Pichia yeast strains have also been constructed using mutagens to improve xylose fermentation and ethanol production. Altogether, these strategieswill not only increase our knowledge on yeast stress response and tolerance mechanisms, but they could also be applied in industrial yeast strain engineering to develop more robust yeast strains for higher bioethanol production.