Ethanol tolerance of immobilized brewers' yeast cells

1995 ◽  
Vol 43 (1) ◽  
pp. 18-24 ◽  
Author(s):  
S. Norton ◽  
K. Watson ◽  
T. D'Amore
Keyword(s):  
Ethanol Tolerance ◽  
Yeast Cells ◽  
Brewers Yeast

Ethanol tolerance of immobilized brewers? yeast cells

1995 ◽  
Vol 43 (1) ◽  
pp. 18-24 ◽  
Author(s):  
S. Norton ◽  
K. Watson ◽  
T. D?Amore
Keyword(s):  
Ethanol Tolerance ◽  
Yeast Cells ◽  
Brewers Yeast

scholarly journals Mitochondrial Superoxide Dismutase and Yap1p Act as a Signaling Module Contributing to Ethanol Tolerance of the Yeast Saccharomyces cerevisiae

2016 ◽  
Vol 83 (3) ◽  
Author(s):  
Anna N. Zyrina ◽  
Ekaterina A. Smirnova ◽  
Olga V. Markova ◽  
Fedor F. Severin ◽  
Dmitry A. Knorre
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Ethanol Tolerance ◽  
Yeast Cells ◽  
Ethanol Stress ◽  
Mitochondrial Enzymes ◽  
Mitochondrial Superoxide ◽  
Mitochondrial Superoxide Dismutase

ABSTRACT There are two superoxide dismutases in the yeast Saccharomyces cerevisiae—cytoplasmic and mitochondrial enzymes. Inactivation of the cytoplasmic enzyme, Sod1p, renders the cells sensitive to a variety of stresses, while inactivation of the mitochondrial isoform, Sod2p, typically has a weaker effect. One exception is ethanol-induced stress. Here we studied the role of Sod2p in ethanol tolerance of yeast. First, we found that repression of SOD2 prevents ethanol-induced relocalization of yeast hydrogen peroxide-sensing transcription factor Yap1p, one of the key stress resistance proteins. In agreement with this, the levels of Trx2p and Gsh1p, proteins encoded by Yap1 target genes, were decreased in the absence of Sod2p. Analysis of the ethanol sensitivities of the cells lacking Sod2p, Yap1p, or both indicated that the two proteins act in the same pathway. Moreover, preconditioning with hydrogen peroxide restored the ethanol resistance of yeast cells with repressed SOD2. Interestingly, we found that mitochondrion-to-nucleus signaling by Rtg proteins antagonizes Yap1p activation. Together, our data suggest that hydrogen peroxide produced by Sod2p activates Yap1p and thus plays a signaling role in ethanol tolerance. IMPORTANCE Baker's yeast harbors multiple systems that ensure tolerance to high concentrations of ethanol. Still, the role of mitochondria under severe ethanol stress in yeast is not completely clear. Our study revealed a signaling function of mitochondria which contributes significantly to the ethanol tolerance of yeast cells. We found that mitochondrial superoxide dismutase Sod2p and cytoplasmic hydrogen peroxide sensor Yap1p act together as a module of the mitochondrion-to-nucleus signaling pathway. We also report cross talk between this pathway and the conventional retrograde signaling cascade activated by dysfunctional mitochondria.

scholarly journals Vacuolar H+-ATPase Protects Saccharomyces cerevisiae Cells against Ethanol-Induced Oxidative and Cell Wall Stresses

2016 ◽  
Vol 82 (10) ◽  
pp. 3121-3130 ◽  
Author(s):  
Sirikarn Charoenbhakdi ◽  
Thanittra Dokpikul ◽  
Thanawat Burphan ◽  
Todsapol Techo ◽  
Choowong Auesukaree
Keyword(s):  
Cell Wall ◽  
Alcoholic Fermentation ◽  
Ethanol Tolerance ◽  
Wall Stress ◽  
Yeast Cells ◽  
Intracellular Acidification ◽  
Straight Chain ◽  
Cell Wall Stress ◽  
Yeast Strains ◽  
Vacuolar Acidification

ABSTRACTDuring fermentation, increased ethanol concentration is a major stress for yeast cells. Vacuolar H+-ATPase (V-ATPase), which plays an important role in the maintenance of intracellular pH homeostasis through vacuolar acidification, has been shown to be required for tolerance to straight-chain alcohols, including ethanol. Since ethanol is known to increase membrane permeability to protons, which then promotes intracellular acidification, it is possible that the V-ATPase is required for recovery from alcohol-induced intracellular acidification. In this study, we show that the effects of straight-chain alcohols on membrane permeabilization and acidification of the cytosol and vacuole are strongly dependent on their lipophilicity. These findings suggest that the membrane-permeabilizing effect of straight-chain alcohols induces cytosolic and vacuolar acidification in a lipophilicity-dependent manner. Surprisingly, after ethanol challenge, the cytosolic pH in Δvma2and Δvma3mutants lacking V-ATPase activity was similar to that of the wild-type strain. It is therefore unlikely that the ethanol-sensitive phenotype ofvmamutants resulted from severe cytosolic acidification. Interestingly, thevmamutants exposed to ethanol exhibited a delay in cell wall remodeling and a significant increase in intracellular reactive oxygen species (ROS). These findings suggest a role for V-ATPase in the regulation of the cell wall stress response and the prevention of endogenous oxidative stress in response to ethanol.IMPORTANCEThe yeastSaccharomyces cerevisiaehas been widely used in the alcoholic fermentation industry. Among the environmental stresses that yeast cells encounter during the process of alcoholic fermentation, ethanol is a major stress factor that inhibits yeast growth and viability, eventually leading to fermentation arrest. This study provides evidence for the molecular mechanisms of ethanol tolerance, which is a desirable characteristic for yeast strains used in alcoholic fermentation. The results revealed that straight-chain alcohols induced cytosolic and vacuolar acidification through their membrane-permeabilizing effects. Contrary to expectations, a role for V-ATPase in the regulation of the cell wall stress response and the prevention of endogenous oxidative stress, but not in the maintenance of intracellular pH, seems to be important for protecting yeast cells against ethanol stress. These findings will expand our understanding of the mechanisms of ethanol tolerance and provide promising clues for the development of ethanol-tolerant yeast strains.

scholarly journals Analysis of lipid composition reveals mechanisms of ethanol tolerance in the model yeast Saccharomyces cerevisiae

2021 ◽  
Author(s):  
M Lairón-Peris ◽  
S. J. Routledge ◽  
J. A. Linney ◽  
J Alonso-del-Real ◽  
C.M. Spickett ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Stress Responses ◽  
Ethanol Tolerance ◽  
Yeast Species ◽  
Culture Media ◽  
Sugar Content ◽  
Yeast Cells ◽  
Yeast Saccharomyces Cerevisiae ◽  
Tolerant Strain ◽  
Cell Factories

Saccharomyces cerevisiae is an important unicellular yeast species within the biotechnological and food and beverage industries. A significant application of this species is the production of ethanol, where concentrations are limited by cellular toxicity, often at the level of the cell membrane. Here, we characterize 61 S. cerevisiae strains for ethanol tolerance and further analyse five representatives with varying ethanol tolerances. The most tolerant strain, AJ4, was dominant in co-culture at 0% and 10% ethanol. Unexpectedly, although it does not have the highest NIC or MIC, MY29 was the dominant strain in co-culture at 6% ethanol, which may be linked to differences in its basal lipidome. Whilst relatively few lipidomic differences were observed between strains, a significantly higher PE concentration was observed in the least tolerant strain, MY26, at 0% and 6% ethanol compared to the other strains that became more similar at 10%, indicating potential involvement of this lipid with ethanol sensitivity. Our findings reveal that AJ4 is best able to adapt its membrane to become more fluid in the presence of ethanol and lipid extracts from AJ4 also form the most permeable membranes. Furthermore, MY26 is least able to modulate fluidity in response to ethanol and membranes formed from extracted lipids are least leaky at physiological ethanol concentrations. Overall, these results reveal a potential mechanism of ethanol tolerance and suggests a limited set of membrane compositions that diverse yeast species use to achieve this. Importance Many microbial processes are not implemented at the industrial level because the product yield is poorer and more expensive than can be achieved by chemical synthesis. It is well established that microbes show stress responses during bioprocessing, and one reason for poor product output from cell factories is production conditions that are ultimately toxic to the cells. During fermentative processes, yeast cells encounter culture media with high sugar content, which is later transformed into high ethanol concentrations. Thus, ethanol toxicity is one of the major stresses in traditional and more recent biotechnological processes. We have performed a multilayer phenotypic and lipidomic characterization of a large number of industrial and environmental strains of Saccharomyces to identify key resistant and non-resistant isolates for future applications.

scholarly journals Viability and Versatility of the Yeast Cell

2004 ◽  
Vol 12 (3) ◽  
pp. 30-33
Author(s):  
Michelle J. Henry-Stanley ◽  
Carol L. Wells
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Yeast Cell ◽  
Candida Utilis ◽  
Paper Industry ◽  
Yeast Cells ◽  
Distilled Spirits ◽  
Eukaryotic Microorganisms ◽  
Brewers Yeast ◽  
Soil And Water

Yeasts are single-celled eukaryotic microorganisms (generally about 5 to 10 microns in diameter) that divide by a budding process and are classified with the fungi. Yeast cells are ubiquitous in our environment and can be found on plants and in soil and water. Yeasts have considerable importance Ln industrial and agricultural settings,Saccharomyces cerevisiae(Figure 1) is also known as “bakers yeast” or “brewers yeast.” Specific strains of yeast are used to make pastries, bread, beer, ale, wine, distilled spirits, and industrial alcohol. In the paper industry,Candida utilisis used to break down die sugars from processed wood pulp. Yeast cells are also nutritious. In some societies, “cloudy” beer (containing yeast cells) provides essential B vitamins, minerals, and amino acids.

Changes of trehalose content and expression of relative genes during the bioethanol fermentation bySaccharomyces cerevisiae

2016 ◽  
Vol 62 (10) ◽  
pp. 827-835 ◽  
Author(s):  
Chenfeng Yi ◽  
Fenglian Wang ◽  
Shijun Dong ◽  
Hao Li
Keyword(s):  
Phase Transition ◽  
Stationary Phase ◽  
Ethanol Tolerance ◽  
Stationary Phases ◽  
Exponential Phase ◽  
Yeast Cells ◽  
Ethanol Stress ◽  
Lag Phase ◽  
Significant Difference ◽  
Trehalose Content

Traditionally, trehalose is considered as a protectant to improve the ethanol tolerance of Saccharomyces cerevisiae. In this study, to clarify the changes and roles of trehalose during the bioethanol fermentation, trehalose content and expression of related genes at lag, exponential, and stationary phases (i.e., 2, 8, and 16 h of batch fermentation process) were determined. Although yeast cells at exponential and stationary phase had higher trehalose content than cells at lag phase (P < 0.01), there was no significant difference in trehalose content between exponential and stationary phases (P > 0.05). Moreover, expression of the trehalose degradation-related genes NTH1 and NTH2 decreased at exponential phase in comparison with that at lag phase; compared with cells at lag phase, cells at stationary phase had higher expression of TPS1, ATH1, NTH1, and NTH2 but lower expression of TPS2. During the lag–exponential phase transition, downregulation of NTH1 and NTH2 promoted accumulation of trehalose, and to some extent, trehalose might confer ethanol tolerance to S. cerevisiae before stationary phase. During the exponential–stationary phase transition, upregulation of TPS1 contributed to accumulation of trehalose, and Tps1 protein might be indispensable in yeast cells to withstand ethanol stress at the stationary phase. Moreover, trehalose would be degraded to supply carbon source at stationary phase.

scholarly journals Rethinking the role of lipids in lager yeast cells during beer fermentation from a transcriptome and systems biology perspective

2020 ◽  
Author(s):  
Diego Bonatto
Keyword(s):  
Systems Biology ◽  
Ethanol Tolerance ◽  
Lipid Biosynthesis ◽  
Yeast Cells ◽  
Biological Processes ◽  
Lager Yeast ◽  
Beer Fermentation ◽  
Ethanol Toxicity ◽  
Transcriptome Analyses ◽  
Cellular Components

AbstractBrewing lager yeast (Saccharomyces pastorianus) is exposed to stressful conditions during beer fermentation, including ethanol toxicity. In response to ethanol toxicity, various biological mechanisms are modulated, including lipid biosynthesis. It is well known that during beer fermentation, the composition of yeast membranes changes in response to ethanol toxicity, making it less fluid and permeable. Additionally, neutral lipids and lipid droplets (LDs) are produced in response to ethanol toxicity. LDs are membranous organelles that transport lipids and proteins, acting as hubs for inter-organellar communication and modulating the activity of mechanisms necessary for ethanol tolerance, such as proteostasis and autophagy. Unfortunately, little is known about the interplay between autophagy, lipid metabolism, and proteostasis (ALP) in lager cells during beer fermentation. Therefore, transcriptome analyses using publicly available DNA microarray data obtained from lager yeast cells were used to identify all the ALP-associated genes that were upregulated during beer fermentation compared to yeast biomass propagation. Thereafter, a top-down systems biology analysis was applied, involving constructing an ALP-associated shortest-pathway protein–protein interaction network (ALP network), identifying important nodes and communities within the ALP network, and identifying the overrepresented biological processes and cellular components using a Gene Ontology (GO) analysis. The transcriptome analyses indicated the upregulation of 204 non-redundant ALP-associated genes during beer fermentation, whose respective proteins interact in the shortest-pathway ALP network. Thirteen communities were selected from the ALP network, and they were associated with multiple overrepresented GO biological processes and cellular components, such as mitophagy, cytoplasm-to-vacuole transport, piecemeal microautophagy of the nucleus, endoplasmic reticulum (ER) stress, ergosterol and lipid biosynthesis, LDs, ER membrane, and phagophore assembly. These results indicate that ethanol tolerance in lager yeasts could be due to the modulation of proteostasis and various forms of autophagy by lipid biosynthesis and LDs, thus highlighting the importance of lipids for beer fermentation.

Acquisition of ethanol tolerance in yeast cells by heat shock

1983 ◽  
Vol 5 (10) ◽  
pp. 683-688 ◽  
Author(s):  
Kenneth Watson ◽  
Rick Cavicchioli
Keyword(s):  
Heat Shock ◽  
Ethanol Tolerance ◽  
Yeast Cells

scholarly journals Ethanol Tolerance in the Yeast Saccharomyces cerevisiae Is Dependent on Cellular Oleic Acid Content

2003 ◽  
Vol 69 (3) ◽  
pp. 1499-1503 ◽  
Author(s):  
Kyung Man You ◽  
Claire-Lise Rosenfield ◽  
Douglas C. Knipple
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Oleic Acid ◽  
Fatty Acid ◽  
Unsaturated Fatty Acid ◽  
Palmitoleic Acid ◽  
Ethanol Tolerance ◽  
Vaccenic Acid ◽  
Yeast Cells ◽  
Oleic Acid Content ◽  
Yeast Saccharomyces Cerevisiae

ABSTRACT In this investigation, we examined the effects of different unsaturated fatty acid compositions of Saccharomyces cerevisiae on the growth-inhibiting effects of ethanol. The unsaturated fatty acid (UFA) composition of S. cerevisiae is relatively simple, consisting almost exclusively of the mono-UFAs palmitoleic acid (Δ9Z-C16:1) and oleic acid (Δ9Z-C18:1), with the former predominating. Both UFAs are formed in S. cerevisiae by the oxygen- and NADH-dependent desaturation of palmitic acid (C16:0) and stearic acid (C18:0), respectively, catalyzed by a single integral membrane desaturase encoded by the OLE1 gene. We systematically altered the UFA composition of yeast cells in a uniform genetic background (i) by genetic complementation of a desaturase-deficient ole1 knockout strain with cDNA expression constructs encoding insect desaturases with distinct regioselectivities (i.e., Δ9 and Δ11) and substrate chain-length preferences (i.e., C16:0 and C18:0); and, (ii) by supplementation of the same strain with synthetic mono-UFAs. Both experimental approaches demonstrated that oleic acid is the most efficacious UFA in overcoming the toxic effects of ethanol in growing yeast cells. Furthermore, the only other UFA tested that conferred a nominal degree of ethanol tolerance is cis-vaccenic acid (Δ11Z-C18:1), whereas neither Δ11Z-C16:1 nor palmitoleic acid (Δ9Z-C16:1) conferred any ethanol tolerance. We also showed that the most ethanol-tolerant transformant, which expresses the insect desaturase TniNPVE, produces twice as much oleic acid as palmitoleic acid in the absence of ethanol and undergoes a fourfold increase in the ratio of oleic acid to palmitoleic acid in response to exposure to 5% ethanol. These findings are consistent with the hypothesis that ethanol tolerance in yeast results from incorporation of oleic acid into lipid membranes, effecting a compensatory decrease in membrane fluidity that counteracts the fluidizing effects of ethanol.

scholarly journals Acquired Resistance to Severe Ethanol Stress on Protein Quality Control in Saccharomyces cerevisiae

2020 ◽  
Author(s):  
Masashi Yoshida ◽  
Sae Kato ◽  
Shizu Fukuda ◽  
Shingo Izawa
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Stress Resistance ◽  
Ethanol Tolerance ◽  
Protein Quality ◽  
Yeast Cells ◽  
Ethanol Stress ◽  
Mild Stress ◽  
Insoluble Protein ◽  
Protein Levels ◽  
Brewing Process

Acute severe ethanol stress (10% v/v) damages proteins and causes the intracellular accumulation of insoluble proteins in Saccharomyces cerevisiae. On the other hand, a pretreatment with mild stress increases tolerance to subsequent severe stress, which is called acquired stress resistance. It currently remains unclear whether the accumulation of insoluble proteins under severe ethanol stress may be mitigated by increasing protein quality control (PQC) activity in cells pretreated with mild stress. In the present study, we examined the induction of resistance to severe ethanol stress in PQC, and confirmed that a pretreatment with 6% (v/v) ethanol or mild thermal stress at 37°C significantly reduced insoluble protein levels and the aggregation of Lsg1, which is prone to denaturation and aggregation by stress, in yeast cells under 10% (v/v) ethanol stress. The induction of this stress resistance required the new synthesis of proteins; the expression of proteins comprising the bi-chaperone system (Hsp104, Ssa3, and Fes1), Sis1, and Hsp42 was up-regulated during the pretreatment and maintained under subsequent severe ethanol stress. Since the pretreated cells of deficient mutants in the bi-chaperone system (fes1Δhsp104Δ and ssa2Δssa3Δssa4Δ) failed to sufficiently reduce insoluble protein levels and Lsg1 aggregation, the enhanced activity of the bi-chaperone system appears to be important for the induction of adequate stress resistance. In contrast, the importance of proteasomes and aggregases (Btn2 and Hsp42) in the induction of stress resistance has not been confirmed. These results provide further insights into the PQC activity of yeast cells under severe ethanol stress, including the brewing process. IMPORTANCE Although the budding yeast S. cerevisiae, which is used in the production of alcoholic beverages and bioethanol, is highly tolerant of ethanol, high concentrations of ethanol are also stressful to the yeast and cause various adverse effects, including protein denaturation. A pretreatment with mild stress improves the ethanol tolerance of yeast cells; however, it currently remains unclear whether it increases PQC activity and reduces the levels of denatured proteins. In the present study, we found that a pre-treatment with mild ethanol up-regulated the expression of proteins involved in PQC and mitigated the accumulation of insoluble proteins, even under severe ethanol stress. These results provide novel insights into ethanol tolerance and the adaptive capacity of yeast. They may also contribute to research on the physiology of yeast cells during the brewing process, in which the concentration of ethanol gradually increases.

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