Physiological and Molecular Characterization of an Oxidative Stress-Resistant Saccharomyces cerevisiae Strain Obtained by Evolutionary Engineering

Oxidative stress is a key attribute that one should considered when using yeast cells for industrial applications due to its direct impact on yeast growth, viability, and productivity. However, little information is currently available regarding the molecular mechanisms of oxidative stress induction and the antioxidant response to increased reactive oxygen species (ROS) in yeasts. In this study, we generated experimentally evolved and genetically stable oxidative stress-resistant S. cerevisiae strain. This evolved strain has elevated trehalose and glycogen production, and up-regulated gene expression profile for that related to stress response, transport, carbohydrate, lipid and co-factor metabolic processes, protein phosphorylation, cell wall organization or biogenesis. In contrast, down-regulated genes were related to ribosome and RNA processing, nuclear transport, tRNA, cell cycle etc. In addition to that, comparative physiological, transcriptomic, and genomic analyses revealed that this oxidative stress resistant strain was also cross-resistant against other stress types including heat, freeze-thaw, ethanol, copper, and salt stress. Single variants identified via whole genome sequencing were primarily related to stress response, cell wall organization, carbohydrate metabolism/transport which support the physiological and transcriptomic results. Overall, this shed light how yeast cells can cope with oxidative stress pressure using their complex molecular mechanisms for the stress resistance and hints on how oxidative stress resistant S. cerevisiae strain can be generated for industrial applications. Oxidative stress resistant Saccharomyces cerevisiae (H7) mutant strain and reference strain were grown in yeast minimal medium. When cultures’ Optical Density (OD600) reached to about 1, which correspond to the logarithmic growth phase of the yeast cells, total RNA isolation was carried out by using RNeasy Mini Kit (Qiagen). The experiment was performed triplicates. Whole-genome microarray analysis was carried out by using Agilent DNA Microarray Technology.