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

Abstract

Oxidative stress is a major stress type observed in yeast bioprocesses, resulting in a decrease in yeast growth, viability, and productivity. Thus, robust yeast strains with increased resistance to oxidative stress are in highly demand by the industry. In addition, oxidative stress is also associated with aging and age-related complex conditions such as cancer and neurodegenerative diseases. Saccharomyces cerevisiae, as a model eukaryote, has been used to study these complex eukaryotic processes. However, the molecular mechanisms underlying oxidative stress responses and resistance are unclear. In this study, we have employed evolutionary engineering (also known as adaptive laboratory evolution – ALE) strategies to obtain an oxidative stress-resistant and genetically stable S. cerevisiae strain. Comparative physiological, transcriptomic, and genomic analyses of the evolved strain were then performed with respect to the reference strain. The results show that the oxidative stress-resistant evolved strain was also cross-resistant against other types of stressors, including heat, freeze-thaw, ethanol, cobalt, iron, and salt. It was also found to have higher levels of trehalose and glycogen production. Further, comparative transcriptomic analysis showed an upregulation of many genes associated with the stress response, transport, carbohydrate, lipid and cofactor metabolic processes, protein phosphorylation, cell wall organization, and biogenesis. Genes that were downregulated included those related to ribosome and RNA processing, nuclear transport, tRNA, and cell cycle. Whole genome re-sequencing analysis of the evolved strain identified mutations in genes related to the stress response, cell wall organization, carbohydrate metabolism/transport, which are in line with the physiological and transcriptomic results, and may give insight toward the complex molecular mechanisms of oxidative stress resistance.

Transcriptome analysis of trembling aspen (Populus tremuloides) under nickel stress

“…Recent findings with yeast cells that are resistant to diverse metals and oxidative stress showed that silver-resistant, iron-resistant, nickel-resistant, and oxidative stress-resistant yeasts had upregulated and mutated genes related to cell wall integrity and organization. Their cell wall integrity test results also revealed that they had increased cell wall integrity levels, indicating the importance of cell wall in stress resistance [ 16 – 18 ].…”

Genomic, transcriptomic, and metabolic characterization of 2-Phenylethanol-resistant Saccharomyces cerevisiae obtained by evolutionary engineering

“…On the other hand, the glycogen content of both strains was not significantly different from each other both in the absence and presence of 2-PE ( Supplementary Figure S4 ). In previous studies dedicated to evolve yeasts to become resistant to either caffeine ( Sürmeli et al, 2019 ), iron ( Balaban et al, 2020 ), silver ( Terzioğlu et al, 2020 ), or oxidative stress ( Kocaefe-Özşen et al, 2022 ), we reported a relationship between resistance to these stresses and cell wall remodeling. Therefore, we also examined whether the resistance to 2-PE entailed some cell wall remodeling by a treatment of the strains with lyticase, a cell wall-degrading enzymatic cocktail ( Kuranda et al, 2006 ).…”

“…Lyticase sensitivity assay was performed according to Kuranda et al (2006) with slight modifications, as described previously ( Kocaefe-Özşen et al, 2022 ). Briefly, overnight cultures of the evolved and the reference strain, grown both in the presence and absence (control) of 3 g/L 2-PE stress were harvested upon centrifugation at 10,000 g for 10 min.…”

Transcriptome analysis reveals multiple targets of erythritol-related transcription factor EUF1 in unconventional yeast Yarrowia Lipolytica

“…Orthologs of some genes regulated by Euf1 were also involved in adaptation to diverse stress conditions. In S. cerevisiae CIT1 and MLS1 were upregulated in strains adapted to oxidative stress [ 49 ], and upregulation of genes encoding alcohol and aldehyde dehydrogenases were observed in strains resistant to 2-Phenylethanol [ 50 ].…”