Transcription Factor ROX1 Controls Oxidative Stress Homeostasis in Saccharomyces cerevisiae at Low pH

Saccharomyces cerevisiae is widely used in food and beverage production but faces stresses such as acidity during processing. In our previous studies, the S. cerevisiae mutant strain TAMC, which can tolerate an acidic environment of pH 2.3, was isolated via adaptive laboratory evolution; however, the genetic basis underlying the acid tolerance of this strain remained unclear. Herein, we aimed to elucidate the genetic basis of TAMC's acid tolerance via genome sequencing and functional analysis. The results revealed that a mutation (mROX1) in transcriptional regulator ROX1 was crucial for acid tolerance. Comparative transcriptome mining and reverse engineering revealed that the mROX1 mutation mediated cellular oxidation-reduction stress homeostasis maintenance by upregulating the expression of superoxide dismutase homologues and catalase, facilitating tolerance to acidity and detoxifying reactive oxygen species. This work uncovers a novel yeast intracellular homeostasis mechanism, providing a potential strategy for engineering novel acid-tolerant microbial cell chassis.