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Overexpression of glutaredoxins enhances physicochemical stress tolerance in Saccharomyces cerevisiae
Abstract
Cellulosic biomass is a renewable substrate for bioethanol generation, but the industrial fermentation performance of Saccharomyces cerevisiae is severely reduced under physicochemical stresses. Eight glutaredoxin (GRX) genes from S. cerevisiae were individually overexpressed and evaluated for stress tolerance. Under heat stress at 42°C, strains overexpressing Grx1, Grx2, and Grx5 exhibited 34.5%±0.2%, 19.6%±5.0%, and 28.0%±2.5% higher OD600 values at 72 h compared to the control strain. Under 1 g/L acetic acid, strains overexpressing Grx1, Grx2, Grx6, and Grx7 showed 13.0%±4.0%, 8.3%±1.4%, 4.3%±0.5%, and 5.9%±1.5% increases in OD600, respectively. ROS quantification revealed that Grx1-, Grx2-, and Grx5-overexpressing strains showed substantially lower intracellular ROS accumulation, with intracellular ROS levels of 36.2%±1.0%, 41.2%±1.7%, and 58.8%±0.8% relative to the control strain (empty POT1 plasmid) at 42°C. Transcriptional analysis further showed distinct stress-responsive expression patterns, with Grx1 and Grx2 exhibiting high basal transcription at 30°C, downregulation at 40°C, and re-induction under acetic acid stress. Collectively, these findings demonstrate that overexpression of the glutaredoxin system improves redox homeostasis and significantly enhances yeast performance under physicochemical stress.
