Acid adaptation for improvement of viability of Saccharomyces cerevisiae during freeze-drying

Summary This work was aimed to investigate its adaptation to moderate acid stress and the resulting improvement in its viability during freeze‐drying. When Saccharomyces cerevisiae UP3OY5 strain was adapted to acid condition (pH 3.5), the viability of acid‐adapted cells (79.9%) was significantly higher than that of control cells (40.5%) after freeze‐drying with trehalose as a carrier. Membrane fatty acid profile of acid‐adapted cells changed significantly in comparison with that of control cells. An increase in fatty acid saturation degree that led to 1.76‐fold increase in the ratio of saturated to unsaturated fatty acids was shown. Intracellular glycogen content was found to be higher than that of control cells. On the contrary, the trehalose content of acid‐adapted cells was found to be much smaller than that of control cells. The key role of acid adaptation in acquiring cross‐protection mechanism was suggested to permit yeast to better survive to freeze‐drying.