A Study of Ethanol Tolerance in Yeast

D’Amore, Tony; Panchal, Chandra J.; Russell, Inge; Stewart, Graham G.

doi:10.3109/07388558909036740

Cited by 142 publications

(76 citation statements)

References 58 publications

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“…Increasing ethanol concentrations also strongly depress fermentation rate and yeast viability. For detailed information on the toxic effects of ethanol, the reader is referred to previous comprehensive reviews (47,65,139,275). The extent of yeast's tolerance to ethanol determines its ethanol productivity and final titer, which is especially relevant in very-high-gravity fermentation (72).…”

Section: Vol 72 2008 Metabolic Engineering Of Saccharomyces Cerevismentioning

confidence: 99%

Progress in Metabolic Engineering of Saccharomyces cerevisiae

Nevoigt

2008

Microbiol Mol Biol Rev

522

333

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SUMMARY The traditional use of the yeast Saccharomyces cerevisiae in alcoholic fermentation has, over time, resulted in substantial accumulated knowledge concerning genetics, physiology, and biochemistry as well as genetic engineering and fermentation technologies. S. cerevisiae has become a platform organism for developing metabolic engineering strategies, methods, and tools. The current review discusses the relevance of several engineering strategies, such as rational and inverse metabolic engineering, evolutionary engineering, and global transcription machinery engineering, in yeast strain improvement. It also summarizes existing tools for fine-tuning and regulating enzyme activities and thus metabolic pathways. Recent examples of yeast metabolic engineering for food, beverage, and industrial biotechnology (bioethanol and bulk and fine chemicals) follow. S. cerevisiae currently enjoys increasing popularity as a production organism in industrial (“white”) biotechnology due to its inherent tolerance of low pH values and high ethanol and inhibitor concentrations and its ability to grow anaerobically. Attention is paid to utilizing lignocellulosic biomass as a potential substrate.

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Section: Vol 72 2008 Metabolic Engineering Of Saccharomyces Cerevismentioning

confidence: 99%

Progress in Metabolic Engineering of Saccharomyces cerevisiae

Nevoigt

2008

Microbiol Mol Biol Rev

522

333

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“…The study of ethanol tolerance in yeast is quite difficult due to the many inhibitory effects on this organism 11,13,14 . Additionally, there is no universally accepted method to define ethanol tolerance.…”

Section: -2863(9'8-32mentioning

confidence: 99%

“…Furthermore, Marechal & Gervais 27 observed cell volume variation in S. cerevisiae during the first 24 h when exposed to various water potentials and attributed their observations to the exit of water flow from the cell. They concluded that hyperosmotic shock in S. cerevisiae resulted in the loss of cell turgor pressure and subsequently a rapid decrease in cytoplasmic water content and cell volume.The study of ethanol tolerance in yeast is quite difficult due to the many inhibitory effects on this organism 11,13,14 . Additionally, there is no universally accepted method to define ethanol tolerance.…”

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The Effects of Osmotic Pressure and Ethanol on Yeast Viability and Morphology

Pratt

Bryce

Stewart

2003

Journal of the Institute of Brewing

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The selection of a brewing yeast strain with the required fermentation and recycling characteristics is critical. The yeast strain will influence the rate and extent of fermentation, the flavour characteristics and the overall quality and stability of the finished beer, and consequently, the economic viability of the brewery. Since high gravity worts can have a deleterious effect on yeast fermentation performance, it is imperative that the strain selected be suitable for this environment, which includes a capacity to withstand high osmotic pressures and elevated ethanol levels. Under controlled in vitro osmotic and ethanol induced stresses, there was a decline in mean cell volume in both lager and ale yeast strains. Whilst significant reductions in viability were observed in the lager strains, the ale strains studied were not affected. Cell surface investigations revealed shrinkage of the yeast cells and crenation of the outside envelope under both stresses, although exposure to ethanol had a more marked effect on the yeast cell surface than sorbitol-induced elevated osmotic pressure.Key words: Cell viability, cell volume, ethanol, high gravity wort, osmotic pressure. -2863(9'8-32In brewing, yeast is recycled and the fact that it is cropped and repitched into subsequent fermentations is one of the differentiating features between brewing and the production of many other alcoholic beverages including Scotch whisky 37 . Consequently, the quality of yeast cropped will not only affect the overall performance of most fermentations but also the quality and stability of the resulting beer. It is important therefore that the factors which influence yeast performance in the brewing process, and particularly in high gravity brewing, are considered, to ensure efficient fermentation and the production of a beer of a consistently high quality and stability. Breweries, the world-over, are continually seeking ways to reduce capital expenditure, labour, utilities, effluent and other operational costs and at the same time ensuring that the quality of their beers remains consistently high. As a result, many are employing the process of high gravity brewing due to its many advantages 39 . Similarly, some breweries have not implemented this process due to its disadvantages 40 . Of significance, are the deleterious effects of this process on yeast fermentation performance 41,43 . Fermentations have been reported to be sluggish due to elevated ethanol levels and high osmotic pressure, resulting in yeast viability and vitality reductions 6 . Osmotic pressure is the force that develops between two solutes of differing concentration separated by a semipermeable membrane 20 . When yeast is exposed to wort it is subjected to an osmotic pressure. Very high osmotic pressures such as those encountered in high gravity worts, may distort yeast metabolism or decrease yeast viability. The extent of the osmotic pressure will depend on the concentration of solutes surrounding the cell 20,23 . It has been shown that increases in wort osmotic pressu...

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“…Therefore, the viability and vitality of Saccharomyces cerevisiae in the stationary phase are key factors in successful vinification. The yeast death phase during winemaking is still a poorly understood process that has been exclusively linked to the toxicity of the high ethanol concentration reached during fermentation (14). Some authors claim that cells start dying when sugar is still present (39), while others state that cells start dying only when all of the sugars have been consumed (6).…”

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Oxidative Stress Tolerance, Adenylate Cyclase, and Autophagy Are Key Players in the Chronological Life Span of Saccharomyces cerevisiae during Winemaking

Orozco

Matallana

Aranda

2012

Appl Environ Microbiol

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bMost grape juice fermentation takes place when yeast cells are in a nondividing state called the stationary phase. Under such circumstances, we aimed to identify the genetic determinants controlling longevity, known as the chronological life span. We identified commercial strains with both short (EC1118) and long (CSM) life spans in laboratory growth medium and compared them under diverse conditions. Strain CSM shows better tolerance to stresses, including oxidative stress, in the stationary phase. This is reflected during winemaking, when this strain has an increased maximum life span. Compared to EC1118, CSM overexpresses a mitochondrial rhodanese gene-like gene, RDL2, whose deletion leads to increased reactive oxygen species production at the end of fermentation and a correlative loss of viability at this point. EC1118 shows faster growth and higher expression of glycolytic genes, and this is related to greater PKA activity due to the upregulation of the adenylate cyclase gene. This phenotype has been linked to the presence of a ␦ element in its promoter, whose removal increases the life span. Finally, EC1118 exhibits a higher level of protein degradation by autophagy, which might help achieve fast growth at the expense of cellular structures and may be relevant for long-term survival under winemaking conditions.

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A Study of Ethanol Tolerance in Yeast

Cited by 142 publications

References 58 publications

Progress in Metabolic Engineering of Saccharomyces cerevisiae

Progress in Metabolic Engineering of Saccharomyces cerevisiae

The Effects of Osmotic Pressure and Ethanol on Yeast Viability and Morphology

Oxidative Stress Tolerance, Adenylate Cyclase, and Autophagy Are Key Players in the Chronological Life Span of Saccharomyces cerevisiae during Winemaking

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