Adaptation of Saccharomyces cerevisiae Cells to High Ethanol Concentration and Changes in Fatty Acid Composition of Membrane and Cell Size

Dinh, Thai Nho; Nagahisa, Keisuke; Hirasawa, Takashi; Furusawa, Chikara; Shimizu, Hiroshi

doi:10.1371/journal.pone.0002623

Cited by 78 publications

(49 citation statements)

References 17 publications

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“…Additionally, the maximum potential bioethanol concentration of 17.15 g/L-which corresponds to 2.17% (v/v)-illustrates that the impact of ethanol concentration within the medium may have a slight effect on the specific growth rate of S. cerevisiae. This is supported by an earlier study by Dinh et al [39], which showed that a higher initial ethanol concentration within fermentation media resulted in an increase in the time required for cells to reach the optimal bioethanol production rate as well as a reduction in the maximum ethanol concentration. Table 2 shows a comparison of the Gompertz coefficients obtained from this study using sorghum leaves and those reported from oil palm frond juice and sugar beet raw juice.…”

Section: Bioethanol Productionsupporting

confidence: 73%

Kinetics of Bioethanol Production from Waste Sorghum Leaves Using Saccharomyces cerevisiae BY4743

Rorke

Kana

2017

Fermentation

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Kinetic models for bioethanol production from waste sorghum leaves by Saccharomyces cerevisiae BY4743 are presented. Fermentation processes were carried out at varied initial glucose concentrations (12.5-30.0 g/L). Experimental data on cell growth and substrate utilisation fit the Monod kinetic model with a coefficient of determination (R 2 ) of 0.95. A maximum specific growth rate (µ max ) and Monod constant (K S ) of 0.176 h −1 and 10.11 g/L, respectively, were obtained. The bioethanol production data fit the modified Gompertz model with an R 2 value of 0.98. A maximum bioethanol production rate (r p,m ) of 0.52 g/L/h, maximum potential bioethanol concentration (P m ) of 17.15 g/L, and a bioethanol production lag time (t L ) of 6.31 h were observed. The obtained Monod and modified Gompertz coefficients indicated that waste sorghum leaves can serve as an efficient substrate for bioethanol production. These models with high accuracy are suitable for the scale-up development of bioethanol production from lignocellulosic feedstocks such as sorghum leaves.

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Section: Bioethanol Productionsupporting

confidence: 73%

Kinetics of Bioethanol Production from Waste Sorghum Leaves Using Saccharomyces cerevisiae BY4743

Rorke

Kana

2017

Fermentation

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“…2A; also see Fig. S2 in the supplemental material), probably because the membrane was damaged by this treatment, as emphasized in previous works (62)(63)(64)(65). We therefore tentatively estimated the thickness of the cell membrane by taking measurements of at least 5 different points per cell and made these measurements for 20 (each) untreated and ethanol-treated cells.…”

Section: Resultsmentioning

confidence: 88%

Evidence for a Role for the Plasma Membrane in the Nanomechanical Properties of the Cell Wall as Revealed by an Atomic Force Microscopy Study of the Response of Saccharomyces cerevisiae to Ethanol Stress

Schiavone

Formosa-Dague

Elsztein

et al. 2016

Appl Environ Microbiol

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A wealth of biochemical and molecular data have been reported regarding ethanol toxicity in the yeast Saccharomyces cerevisiae. However, direct physical data on the effects of ethanol stress on yeast cells are almost nonexistent. This lack of information can now be addressed by using atomic force microscopy (AFM) technology. In this report, we show that the stiffness of glucosegrown yeast cells challenged with 9% (vol/vol) ethanol for 5 h was dramatically reduced, as shown by a 5-fold drop of Young's modulus. Quite unexpectedly, a mutant deficient in the Msn2/Msn4 transcription factor, which is known to mediate the ethanol stress response, exhibited a low level of stiffness similar to that of ethanol-treated wild-type cells. Reciprocally, the stiffness of yeast cells overexpressing MSN2 was about 35% higher than that of the wild type but was nevertheless reduced 3-to 4-fold upon exposure to ethanol. Based on these and other data presented herein, we postulated that the effect of ethanol on cell stiffness may not be mediated through Msn2/Msn4, even though this transcription factor appears to be a determinant in the nanomechanical properties of the cell wall. On the other hand, we found that as with ethanol, the treatment of yeast with the antifungal amphotericin B caused a significant reduction of cell wall stiffness. Since both this drug and ethanol are known to alter, albeit by different means, the fluidity and structure of the plasma membrane, these data led to the proposition that the cell membrane contributes to the biophysical properties of yeast cells. IMPORTANCEEthanol is the main product of yeast fermentation but is also a toxic compound for this process. Understanding the mechanism of this toxicity is of great importance for industrial applications. While most research has focused on genomic studies of ethanol tolerance, we investigated the effects of ethanol at the biophysical level and found that ethanol causes a strong reduction of the cell wall rigidity (or stiffness). We ascribed this effect to the action of ethanol perturbing the cell membrane integrity and hence proposed that the cell membrane contributes to the cell wall nanomechanical properties. T he yeast Saccharomyces cerevisiae is a remarkable ethanol producer that is also very sensitive to its main fermentative product. At low to moderate concentrations (5 to 7%), ethanol mainly affects the growth rate, and at higher concentrations (Ͼ10%), it can strongly impair cell integrity, eventually leading to cell death with features of apoptosis (1). These inhibitory and toxic effects are ascribed to the fact that ethanol alters cell membrane fluidity and dissipates the transmembrane electrochemical potential, thereby creating permeability to ionic species and causing leakage of metabolites (2). Recent works using lipidomic methodologies confirmed the relationship between the composition of lipids, notably ergosterol and unsaturated fatty acids, and ethanol tolerance (3, 4). Moreover, as it diffuses freely into cells, ethanol at high concen...

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“…Given the potential of adaptive evolution to generate mutants with improved stress tolerance, it is surprising that there are only two reported studies that used this approach to improve ethanol tolerance in yeast [7,12]. Brown and Oliver [7] created ethanol-tolerant mutants of S. uvarum using continuous culture with frequent, semi-continuous ethanol addition.…”

Section: Introductionmentioning

confidence: 99%

“…Five mutants were isolated that showed higher CO 2 production rates compared with wild type in the presence and absence of ethanol; however, variant phenotypes were not further characterised. Dinh et al [12] increased the ethanol concentration of serial batch S. cerevisiae cultures from 2.5% to 10% (v/v) ethanol over a period of 28 days (ca. 100 generations).…”

Section: Introductionmentioning

confidence: 99%

Generation and characterisation of stable ethanol-tolerant mutants of Saccharomyces cerevisiae

Stanley

Fraser

Chambers

et al. 2009

J Ind Microbiol Biotechnol

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Saccharomyces spp. are widely used for ethanologenic fermentations, however yeast metabolic rate and viability decrease as ethanol accumulates during fermentation, compromising ethanol yield. Improving ethanol tolerance in yeast should, therefore, reduce the impact of ethanol toxicity on fermentation performance. The purpose of the current work was to generate and characterise ethanol-tolerant yeast mutants by subjecting mutagenised and non-mutagenised populations of Saccharomyces cerevisiae W303-1A to adaptive evolution using ethanol stress as a selection pressure. Mutants CM1 (chemically mutagenised) and SM1 (spontaneous) had increased acclimation and growth rates when cultivated in sub-lethal ethanol concentrations, and their survivability in lethal ethanol concentrations was considerably improved compared with the parent strain. The mutants utilised glucose at a higher rate than the parent in the presence of ethanol and an initial glucose concentration of 20 g l(-1). At a glucose concentration of 100 g l(-1), SM1 had the highest glucose utilisation rate in the presence or absence of ethanol. The mutants produced substantially more glycerol than the parent and, although acetate was only detectable in ethanol-stressed cultures, both mutants produced more acetate than the parent. It is suggested that the increased ethanol tolerance of the mutants is due to their elevated glycerol production rates and the potential of this to increase the ratio of oxidised and reduced forms of nicotinamide adenine dinucleotide (NAD(+)/NADH) in an ethanol-compromised cell, stimulating glycolytic activity.

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Adaptation of Saccharomyces cerevisiae Cells to High Ethanol Concentration and Changes in Fatty Acid Composition of Membrane and Cell Size

Cited by 78 publications

References 17 publications

Kinetics of Bioethanol Production from Waste Sorghum Leaves Using Saccharomyces cerevisiae BY4743

Kinetics of Bioethanol Production from Waste Sorghum Leaves Using Saccharomyces cerevisiae BY4743

Evidence for a Role for the Plasma Membrane in the Nanomechanical Properties of the Cell Wall as Revealed by an Atomic Force Microscopy Study of the Response of Saccharomyces cerevisiae to Ethanol Stress

Generation and characterisation of stable ethanol-tolerant mutants of Saccharomyces cerevisiae

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