Osmotic tolerance in Saccharomyces cerevisiae: Implications for food and bioethanol industries

Saccharomyces cerevisiae, commonly known as baker's or brewer's yeast, holds an important position in industrial microbiology. This unicellular eukaryote is widely involved in food processing and bioethanol production. In food processing, S. cerevisiae contributes to fermentation processes, producing crucial organoleptic compounds for leavening bread and crafting fermented beverages such as beer, wine, and spirits. It also serves as a key player in bioethanol production, offering a sustainable alternative to fossil fuels. However, S. cerevisiae encounters various stressors during industrial fermentation, particularly osmotic stress triggered by high sugar or salt concentrations. To overcome this challenge, yeast employs a complex array of mechanisms, including osmolyte accumulation, membrane lipid modification, and stress-responsive gene modulation. In this review, we elucidate the adaptive mechanisms employed by S. cerevisiae to mitigate osmotic stress within the food and bioethanol sectors. We explore the effectiveness of targeted genetic modifications to improve the response of yeast to osmotic shock, considering both individual and combined gene manipulations. Furthermore, we scrutinize the contributions of adaptive evolution strategies toward increasing yeast osmo-tolerance across diverse industrial contexts. We also provide an overview novel yeast strains with high osmo-tolerance from natural origins, offering possibilities for their use in future industrial settings.