Ethanol Toxicity and Ethanol Tolerance in Yeasts

Uden, N. van

doi:10.1016/b978-0-12-040308-0.50006-9

Cited by 106 publications

(80 citation statements)

References 114 publications

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“…In the present study, white grape must was fermented by an enological S. cerevisiae strain at temperatures used in wineries: 15°C (commonly used for white wine), 25°C (standard lab conditions), and 30°C (commonly used for red wine). We anticipated that temperature would also affect Hϩ homeostasis, acting synergistically with ethanol, as described in classical works by van Uden and coworkers (17,35).…”

Section: Discussionmentioning

confidence: 97%

“…This balance is also supported by the cell buffering capacity (22) and vacuolar transport (34). Ethanol interferes with this delicate equilibrium by inhibiting mediated transport and enhancing passive diffusion (20,35), disturbing both intracellular pH (pH in ) and proton motive force across the plasma membrane (18). In the past, the ability of yeasts to acidify the environment has been suggested to be an indicator of good metabolic performance and ethanol tolerance (11,23).…”

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confidence: 99%

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Peculiar H ⁺ Homeostasis of Saccharomyces cerevisiae during the Late Stages of Wine Fermentation

Viana¹,

Loureiro-Dias²,

Loureiro³

et al. 2012

Appl Environ Microbiol

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ABSTRACTIntracellular pH (pHin) is a tightly regulated physiological parameter, which controls cell performance in all living systems. The purpose of this work was to evaluate if and how H+homeostasis is accomplished by an industrial wine strain ofSaccharomyces cerevisiaewhile fermenting real must under the harsh winery conditions prevalent in the late stages of the fermentation process, in particular low pH and high ethanol concentrations and temperature. Cells grown at 15, 25, and 30°C were harvested in exponential and early and late stationary phases. Intracellular pH remained in the range of 6.0 to 6.4, decreasing significantly only by the end of glucose fermentation, in particular at lower temperatures (pHin5.2 at 15°C), although the cells remained viable and metabolically active. The cell capability of extruding H+via H+-ATPase and of keeping H+out by means of an impermeable membrane were evaluated as potential mechanisms of H+homeostasis. At 30°C, H+efflux was higher in all stages. The most striking observation was that cells in late stationary phase became almost impermeable to H+. Even when these cells were challenged with high ethanol concentrations (up to 20%) added in the assay, their permeability to H+remained very low, being almost undetectable at 15°C. Comparatively, ethanol significantly increased the H+permeability of cells in exponential phase. Understanding the molecular and physiological events underlying yeast H+homeostasis at late stages of fermentations may contribute to the development of more robust strains suitable to efficiently produce a high-quality wine.

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Section: Discussionmentioning

confidence: 97%

mentioning

confidence: 99%

Peculiar H ⁺ Homeostasis of Saccharomyces cerevisiae during the Late Stages of Wine Fermentation

Viana¹,

Loureiro-Dias²,

Loureiro³

et al. 2012

Appl Environ Microbiol

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“…O 1991 SGM transport (Freeze et af., 1973;van Uden, 1985). Cytoplasmic enzymes might also be adversely affected by a decrease in the internal pH (pH,) caused by the dissociation of octanoic acid (pK, 4.9) in the cytoplasm (pHi -7.0) (Cole & Keenan, 1987;Pampulha & Loureiro-Dias, 1989;Krebs et al, 1983).…”

Section: -6293mentioning

confidence: 99%

Activation of plasma membrane ATPase of Saccharomyces cerevisiae by octanoic acid

Viegas

Sá‐Correia²

1991

Journal of General Microbiology

143

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Plasma membrane ATPase activity of Saccharomyces cerettisiae IGC 3507111 grown in the presence of the lipophilic acid octanoic acid I450 mg I-' (0.03435 mM), pH 4.01 was 1-5-fold higher than that in cells grown in its absence. The K,,, for ATP, the pH profile and the sensitivity to orthovanadate of the basal and the activated forms of the membrane ATPase were identical. This activation was closely associated with a decrease in the biomass yield and an increase in the ethanol yield, and was rapidly reversed in uino after removal of the acid. However, the activated level was preserved when membranes were extracted and subjected to manipulations which eliminated or decreased octanoic acid incorporation in the plasma membrane. The activity of the basal plasma membrane ATPase in the total membrane fraction was slightly increased by incubation at pH6.5 with octanoic acid at 100 mg I-' or less (2.4 mg acid form plus 97.6 mg octanoate ion 1-l). However, destruction of the permeability barrier between the enzyme and its substrate could not explain the in tlitfo activation. A role for plasma membrane ATPase activation in the regulation of the intracellular pH (pHi) of cells grown with octanoic acid was not proven.

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“…However, the stress induced by increasing amounts of ethanol, accumulated to toxic concentrations during ethanolic fermentation, is the major factor responsible for reduced ethanol production and, eventually, for stuck fermentations (14). Thus, yeast strains that can endure stress imposed by high ethanol concentrations are highly desired.Throughout the years many efforts to characterize the mechanisms underlying ethanol stress tolerance, aiming to increase ethanol productivity, have been made (3,16,45,53). The successful engineering of yeast transcription machinery for this purpose was recently reported (3).…”

mentioning

confidence: 99%

Genome-Wide Identification of S accharomyces cerevisiae Genes Required for Maximal Tolerance to Ethanol

Teixeira

Raposo

Mira

et al. 2009

Appl Environ Microbiol

188

192

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The understanding of the molecular basis of yeast resistance to ethanol may guide the design of rational strategies to increase process performance in industrial alcoholic fermentations. In this study, the yeast disruptome was screened for mutants with differential susceptibility to stress induced by high ethanol concentrations in minimal growth medium. Over 250 determinants of resistance to ethanol were identified. The most significant gene ontology terms enriched in this data set are those associated with intracellular organization, biogenesis, and transport, in particular, regarding the vacuole, the peroxisome, the endosome, and the cytoskeleton, and those associated with the transcriptional machinery. Saccharomyces cerevisiae and related yeast species have been extensively used in fermentation, wine making, sake making, and brewing processes. Bioethanol production by yeast is also a growing industry due to energy and environmental demands (38). The successful performance of alcoholic fermentations depends on the ability of the yeast strains used to cope with a number of stress factors occurring during the process (45, 48). These include osmotic pressure imposed by initial high sugar concentration and stress induced by fermentation end products or subproducts such as ethanol and acetate. However, the stress induced by increasing amounts of ethanol, accumulated to toxic concentrations during ethanolic fermentation, is the major factor responsible for reduced ethanol production and, eventually, for stuck fermentations (14). Thus, yeast strains that can endure stress imposed by high ethanol concentrations are highly desired.Throughout the years many efforts to characterize the mechanisms underlying ethanol stress tolerance, aiming to increase ethanol productivity, have been made (3,16,45,53). The successful engineering of yeast transcription machinery for this purpose was recently reported (3). A number of studies based on detailed physiological and molecular analyses have contributed to increasing the understanding of the processes underlying ethanol toxicity and yeast tolerance of stress induced by this metabolite (34)(35)(36)45). These studies indicate that ethanol interferes with membrane lipid organization, affecting its function as a matrix for enzymes, perturbing the conformation and function of membrane transporters, increasing the nonspecific plasma membrane permeability, and leading to the dissipation of transmembrane electrochemical potential (36,45). Concomitantly, yeast responses to ethanol-induced stress include changes in the levels and composition of membrane phospholipids and ergosterol (1,6,53). Through its effect at the level of plasma membrane organization and function, ethanol also produces intracellular acidification (26,(34)(35)(36). In response to this effect, yeast exhibits increased plasma membrane H ϩ -ATPase activity, which is important to maintain the intracellular pH and secondary transport mechanisms, which are dependent on the proton gradient across the plasma membrane (1,29,31,34...

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Ethanol Toxicity and Ethanol Tolerance in Yeasts

Cited by 106 publications

References 114 publications

Peculiar H ⁺ Homeostasis of Saccharomyces cerevisiae during the Late Stages of Wine Fermentation

Peculiar H ⁺ Homeostasis of Saccharomyces cerevisiae during the Late Stages of Wine Fermentation

Activation of plasma membrane ATPase of Saccharomyces cerevisiae by octanoic acid

Genome-Wide Identification of S accharomyces cerevisiae Genes Required for Maximal Tolerance to Ethanol

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Ethanol Toxicity and Ethanol Tolerance in Yeasts

Cited by 106 publications

References 114 publications

Peculiar H + Homeostasis of Saccharomyces cerevisiae during the Late Stages of Wine Fermentation

Peculiar H + Homeostasis of Saccharomyces cerevisiae during the Late Stages of Wine Fermentation

Activation of plasma membrane ATPase of Saccharomyces cerevisiae by octanoic acid

Genome-Wide Identification of S accharomyces cerevisiae Genes Required for Maximal Tolerance to Ethanol

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Product

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Peculiar H ⁺ Homeostasis of Saccharomyces cerevisiae during the Late Stages of Wine Fermentation

Peculiar H ⁺ Homeostasis of Saccharomyces cerevisiae during the Late Stages of Wine Fermentation