Genetic Dissection of Ethanol Tolerance in the Budding Yeast Saccharomyces cerevisiae

Abstract

Uncovering genetic control of variation in ethanol tolerance in natural populations of yeast Saccharomyces cerevisiae is essential for understanding the evolution of fermentation, the dominant lifestyle of the species, and for improving efficiency of selection for strains with high ethanol tolerance, a character of great economic value for the brewing and biofuel industries. To date, as many as 251 genes have been predicted to be involved in influencing this character. Candidacy of these genes was determined from a tested phenotypic effect following gene knockout, from an induced change in gene function under an ethanol stress condition, or by mutagenesis. This article represents the first genomics approach for dissecting genetic variation in ethanol tolerance between two yeast strains with a highly divergent trait phenotype. We developed a simple but reliable experimental protocol for scoring the phenotype and a set of STR/SNP markers evenly covering the whole genome. We created a mapping population comprising 319 segregants from crossing the parental strains. On the basis of the data sets, we find that the tolerance trait has a high heritability and that additive genetic variance dominates genetic variation of the trait. Segregation at five QTL detected has explained $50% of phenotypic variation; in particular, the major QTL mapped on yeast chromosome 9 has accounted for a quarter of the phenotypic variation. We integrated the QTL analysis with the predicted candidacy of ethanol resistance genes and found that only a few of these candidates fall in the QTL regions.

Ethanol Production in Brazil: The Industrial Process and Its Impact on Yeast Fermentation

“…The genetic basis for ethanol tolerance is polygenic and complex. More than 250 genes seem to be involved with this trait (Alexandre et al, 2001;Hu et al, 2007). The majority of these genes are related to energy metabolism, lipid synthesis, ionic homeostasis, trehalose synthesis, etc.…”

Growth Kinetics for the Selection of Yeast Strains for Fermented Beverages

“…Ethanol also causes the denaturation of hydrophilic and hydrophobic proteins, affecting various transport systems such as the general amino acid permease and glucose uptake processes [18]. Regarding molecular response of S. cerevisiae in the presence of ethanol, it increases the expression of genes associated with glycolysis and mitochondrial function and decreases gene expression in energy-demanding growth-related processes; it also induces the production of heat shock-like proteins, lowering the rate of RNA and protein accumulation, enhancing the frequency of small mutations, altering metabolism, denaturing intracellular proteins and glycolytic enzymes, and reducing their activity [39].…”

Latest Frontiers in the Biotechnologies for Ethanol Production from Lignocellulosic Biomass

“…In particular, at low concentrations, ethanol retards the growth rate of yeasts and inhibits cell division, while high ethanol concentrations reduce cells viability and increase their death (Stanley et al, 2010). Furthermore, ethanol stress alters the metabolism (Hu et al, 2007) mostly acting on the plasma membrane and on the cytosolic enzymes (AnsanayGaleote et al, 2001, Lopes & Sola-Penna, 2001). Exposure to ethanol causes also a disruption of the membrane structure resulting in a loss of electrochemical gradients and transport associated to the membrane (D' Amore et al, 1990).…”