Mechanism of enhanced salt tolerance in Saccharomyces cerevisiae by CRZ1 overexpression

Achieving high-gravity fermentation in the industrial production of fuel ethanol, and enhancing the fermentation efficiency of high-salt raw materials, such as waste molasses, can significantly reduce wastewater output and process costs. Therefore, the development of hyperosmotic-tolerant industrial Saccharomyces cerevisiae strains, capable of resisting high-salt stress, offers both environmental and economic benefits. Our previous study highlighted the potential of CRZ1 overexpression as a strategy to improve the yeast strain's resistance to high-salt stress, however, the underlying molecular mechanisms remain unexplored. The fermentation capabilities of the CRZ1-overexpressing strain, KCR3, and its parental strain, KF7, were evaluated under condition of 1.25 M NaCl at 35 °C. Compared to KF7, KCR3 showed an 81% increase in glucose consumption (129.25 ± 0.83 g/L) and a 105% increase in ethanol production (47.59 ± 0.93 g/L), with a yield of 0.37 g/g. Comparative transcriptomic analysis showed that under high-salt stress, KCR3 exhibited significantly upregulated expression of genes associated with ion transport, stress response, gluconeogenesis, and the utilization of alternative carbon sources, while genes related to glycolysis and the biosynthesis of ribosomes, amino acids, and fatty acids were notably downregulated compared to KF7. Crz1 likely expands its influence by regulating the expression of numerous transcription factors, thereby impacting genes involved in multiple aspects of cellular function. The study revealed the regulatory mechanism of Crz1 under high-salt stress, thereby providing guidance for the construction of salt-tolerant strains.