Yeast

11 Key excerpts on "Yeast"

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  Fungi

  Experimental Methods In Biology, Second Edition

  • Ramesh Maheshwari(Author)
  • 2016(Publication Date)
  • CRC Press

    (Publisher)

  161 CHAPTER 9 Yeast A Unicellular Paradigm for Complex Biological Processes Amitabha Chaudhuri Genentech Inc., South San Francisco, California In short order, Yeast became a supermodel, challenging even E. coli in the visibility of its contributions. —Rowland H. Davis (2003) Since antiquity, Yeast has been domesticated unwittingly or purposefully for the conversion of grape juice into wine by a process called fermentation. In the 18th century, the French chem-ist Antoine Lavoisier (1734–1794) showed that sugar in grape juice was transformed into ethanol during fermentation. Theodor Schwann (1810–1882) and Charles Cagniard-Latour (1777–1859) microscopically examined fermentation mixtures and advanced the view that the “force” that drove fermentation is “a mass of globules that reproduces by budding” and is a consequence of the growth of Yeast—an idea that was quickly rejected by the influential German chemist Justus von Liebig, who maintained that the murkiness in fermenting liquid was not due to a living organism. Based on controlled experiments, chemical analyses of broth, and microscopic examinations of the sedi-ment from successful and “diseased” fermentation vats, the versatile French scientist Louis Pasteur (1822–1895) concluded that Yeast cells did not spontaneously arise from fermenting liquid but from preexisting cells. He identified Yeast as the causative agent of alcoholic fermentation. The brewer’s Yeast Saccharomyces cerevisiae has today become a supermodel—“an organism that reveals and integrates many diverse biological findings applying to most living things” (Davis, 2003). A number of investigators, in approximately 700 laboratories around the world, have joined hands to make this fungus (though rather atypical) a model of all model organisms. Its advantages for the study of physiology and eukaryotic gene functions are: • Its unicellular nature, making it a eukaryotic counterpart of E.

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  Environmental Pollution Control Microbiology

  A Fifty-Year Perspective

  • Ross E. McKinney(Author)
  • 2004(Publication Date)
  • CRC Press

    (Publisher)

  Yeasts are nonphotosynthetic microorganisms that have a separate nucleus and a complex life cycle. They are larger than bacteria and appear to be spherical to egg shaped. They are nonmotile and reproduce asexually by budding. Sexual reproduction results in the formation of ascospores. Most Yeasts are non-pathogenic; but a few Yeast can grow parasitically in the right environment. The primary role for Yeast is in alcoholic fermentation and in bread manufacturing, although they have been used for enzyme and vitamin production. The Saccharomycetes cerevisiae have been studied the most from a biochemical point of view. The ability of Yeasts to metabolize natural sugars has resulted in their wide distribution throughout the environment. A drawing of Yeast cells undergoing budding is shown in Figure 4–3. The new cell expands as it develops its chemical structure. As soon as the new cell has sufficient chemical composition, it breaks free, creating two separate cells. Although Yeast cells are non-motile, they tend to remain dispersed until the substrate has been metabolized. The Yeast cells then flocculate into large masses of cells that settle out under quiescent conditions. The flocculating characteristics of Yeasts are very valuable in the fermentation industry. When the sugars have been converted to alcohol and new cell mass, the cells flocculate and settle out, leaving a clear liquid above the Yeast. Calleja indicated that the material around the Yeast cells that produces the flocculation is primarily carbohydrate material. It appears that Yeasts and bacteria have similar mechanisms for flocculation. The accumulation of polysaccharide material around older cells provides surfaces with few ionizable groups, giving a large surface area with a low surface charge. The cells tend to form aggregates with strong Van der Waal surface attraction forces holding them together

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  Fermented Foods, Part I

  Biochemistry and Biotechnology

  • Didier Montet, Ramesh C. Ray, Didier Montet, Ramesh C. Ray(Authors)
  • 2016(Publication Date)
  • CRC Press

    (Publisher)

  Figure 1. Saccharomyces cerevisiae (a) colonies on YPD agar medium, (b) microscopic view and (c) scanning electron micrograph. 3.1 Classification Yeasts are eukaryotic microorganisms classified in the kingdom fungi with 1,500 species currently described, and estimated to be 1% of all fungal species (Kurtzman and Piškur 2006). They are widespread in natural environments including the normal microbial flora of humans, plants, airborne particles, water, food products, and many other ecological niches. Yeasts do not form a single taxonomic or phylogenetic group. The term ‘Yeast’ is often taken as a synonym for S. cerevisiae , but the phylogenetic diversity of Yeasts is shown by their placement in two separate phyla: the Ascomycota and the Basidiomycota whose vegetative growth results predominantly from budding or fission, and which do not form their sexual states within or upon a fruiting body (Kurtzman and Fell 1998). Phylogenetic analysis of the phylum Ascomycota has significantly changed Yeast classification in recent years (Hibbett et al. 2007, Kurtzman et al. 2011). a) c) b) 4 Fermented Foods—Part I: Biochemistry and Biotechnology 3.2 Yeast Cell Structure Yeasts consist of single cells which are smaller than animal and plant cells but larger than bacteria. There is a cell wall on the outside of the cell and the inside of the cell contains cytoplasm having a nucleus, mitochondria and ribosomes (Fig. 2). The cell wall in Yeast is a two layered structure, the inner layer is made up of β-1–3-glucane linked covalently to chitin and is responsible for the stability of Yeast cells. In contrast, the outer layer consists of densely packed glycosylated mannoproteins which decrease the permeability. In addition, hydrophilic attributes of the cell wall are achieved by phosphorylation of the mannoproteins (Lipke and Ovalle 1998).

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  Biotechnological Applications of Extremophilic Microorganisms

  • Natuschka M. Lee(Author)
  • 2020(Publication Date)
  • De Gruyter

    (Publisher)

  9 ]).

  The number of Yeast species described by morphological and molecular identification has increased significantly since the mid-1950s, from 164 species to over 1500 Yeast species today, which corresponds to about 1.2% of all so far officially described fungal species [10 ]. Some of these Yeasts are ubiquitous generalists and encountered in many environments, while others are more specific. Some Yeast taxa are represented by a large amount of culturable strains; however, about one third of all so far described Yeast taxa are represented by only one strain [11 ].

  13.1.3  Cultivation of Yeasts

  Molecular biological methods have opened up new possibilities to describe Yeast biology and to screen for novel Yeast species. However, more traditional cultivation methods remain important as they form the very basis for retrieving a live Yeast strain for advanced biological studies or to employ in biotechnological processes. Since the early history of mankind, humans have been growing Yeasts for different purposes, such as for baking and fermentation. These cultivations arose spontaneously since Yeasts are present in many environments, in particular on media rich with carbohydrates like sugar compounds. Growing Yeast in the laboratory is relatively straightforward [12 ]. Most media for cultivation of Yeast contain peptone, Yeast extract, glucose and/or malt extract, although these must be modified further for different Yeast species. For specific enrichment of novel Yeast species, especially from extreme environments, it is crucial to modify both the medium composition and the cultivation conditions with regard to pH, temperature, redox, etc. For the future screening of novel extremophilic Yeast species, it is most likely necessary to improve cultivation strategies further. The authors in Reference [13

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  Yeasts: From Nature to Bioprocesses

  • Sérgio Luiz Alves Júnior, Helen Treichel, Thiago Olitta Basso, Boris Ugarte Stambuk, Sérgio Luiz Alves Júnior, Helen Treichel, Thiago Olitta Basso, Boris Ugarte Stambuk(Authors)
  • 2022(Publication Date)
  • Bentham Science Publishers

    (Publisher)

  15 ]. Indeed, these microorganisms have proven to be increasingly versatile; not withstanding the countless industrial processes in which these microorganisms are already employed, it seems that they can be applied in an even greater variety of bioprocesses in the future. This chapter will summarise the main biotechnological applications of Yeasts and outline their ecological roles, which also positively impact human welfare.

  THE THINGS WE LOVE THE MOST

  The most traditional biotechnological products, whose processing involves the use of Yeasts, are also the most profitable ones. Besides, these products are also related to the joy, happiness, sociability, and pleasure of individuals. Therefore, they are very likely the bioproducts that humans enjoy the most. Together these industrial segments of joy comprise a trillionaire market, surpassing US$ 1.3 trillion worth of value.

  Alcoholic Beverages

  Most alcoholic beverages are produced due to the fermentation capacity of Yeast cells. In this scenario, the species S. cerevisiae stands out as the primary Yeast used for the beverages with the highest production volume and the most extensive market sizes (Table

  1

  ).

  Table 1 Alcoholic beverages and their markets.

  Dominant Yeast Species in the Processes	Beverage	Global Productiona	Global Market Size	References/Sources
  S. cerevisiae and S. pastorianus	Beer	194 billion L	US$ 623 billion	[17 , 19 ]
  S. cerevisiae	Wine	29.2 billion L	US$ 327 billion	[17 , 18 , 20 ]
  S. cerevisiae	Whiskey	5.2 billion L	US$ 60 billion	[21 - 23 ]
  S. cerevisiae	Vodka	3 billion L	US$ 45 billion	[24 - 26 ]
  S. cerevisiae	Tequila	0.25 billion L	US$ 10 billion	[27 - 29 ]
  S. cerevisiae	Sake	0.6 billion L	US$ 9 billion	[30 - 32 ]
  S. cerevisiae	Cachaça	1.8 billion L	US$ 2 billion	[33 , 34 ]

  a Approximated values per year.

  Beer is a non-distilled beverage obtained from the fermentation of a wort composed of malted cereals, hops, and freshwater. Besides its millenary history, beer is now the leading alcoholic product consumed in the world. Its production has increased gradually over the last decades [16 ], reaching 194 billion liters in 2018. This amount represented a 50% increase in the last two decades and was six times higher than the wine production in that same year (29.2 billion liters) [17

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  Brewing

  Science and Practice

  • D E Briggs, P A Brookes, R Stevens, C A Boulton(Authors)
  • 2004(Publication Date)
  • Woodhead Publishing

    (Publisher)

  Rose and Harrison, 1971 ). An assistant of Hansen, Schiönning reported the occurrence of a sexual phase in the Yeast life cycle. This was confirmed in the 1930s when Øjvind Winge also working at the Carlsberg Foundation provided a full description of the Yeast haploand diplophases.

  As early as 1897, Büchner demonstrated the formation of ethanol and carbon dioxide from sugar using a cell-free extract of Yeast, thereby providing the foundation for the development of modern biochemistry. Yeast has been used as a convenient experimental organism in many subsequent investigations. The zymologist, A. H. Rose, proposed in the introduction to the second volume of the first edition of The Yeasts (Rose and Harrison, 1971 ) the initiation of 'Project Y'. This suggested that Yeast be used as a model eukaryotic organism in an integrated approach to the study of cell biology. This challenge has been taken up and the academic literature devoted to Yeast in general and Saccharomyces cerevisiae in particular is now immense. Many of the discoveries in cell biology, physiology, biochemistry and genetics were made using Yeast cells. Probably, S. cerevisiae is the most extensively studied cell. This has culminated in the sequencing of the entire genome of S. cerevisiae , the first species for which this has been accomplished (

  Goffeau et al. , 1996

  ).

  11.2 Taxonomy

  Taxonomy is the science of the classification of organisms. Using criteria such as morphology, life cycle, immunological properties, biochemical capabilities and genetic analysis, organisms are grouped into hierarchies of relatedness and difference. Systems of taxonomy indicate functional and evolutionary relationships between groups of organisms and they provide a framework for identifying unknown types. Taxonomy has practical importance in brewing. It allows the identification of proprietary Yeast strains and the ability to distinguish these from contaminants such as wild Yeasts.

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  Handbook of Enology, Volume 1

  The Microbiology of Wine and Vinifications

  • Pascal Ribéreau-Gayon, Denis Dubourdieu, Bernard B. Donèche, Aline A. Lonvaud, John Towey(Authors)
  • 2021(Publication Date)
  • Wiley

    (Publisher)

  CHAPTER 1 Yeasts

  1. 1.1 Introduction
  2. 1.2 The Cell Wall
  3. 1.3 The Plasma Membrane
  4. 1.4 The Cytoplasm and Its Organelles
  5. 1.5 The Nucleus
  6. 1.6 Reproduction and the Yeast Biological Cycle
  7. 1.7 The Killer Phenomenon
  8. 1.8 Classification of Yeast Species
  9. 1.9 Identification of WineYeast Strains
  10. 1.10 Ecology of Grape and Wine Yeasts

  1.1 Introduction

  Man has been making bread and fermented beverages since the beginning of recordedhistory. Yet the role of Yeasts in alcoholic fermentation, particularly in the transformation of grapes into wine, was only clearly established in the middle of the 19th century. The ancients explained the boiling during fermentation (from the Latin fervere, to boil) as a reaction between substances that come into contact with each other during crushing to produce effervescence. In 1680, a Dutch cloth merchant, Antonie van Leeuwenhoek, first observed Yeasts in beer wort using a microscope that he designed and produced. He did not, however, establish a relationship between these corpuscles and alcoholic fermentation. It was not until the end of the 18th century that Antoine Lavoisier began the chemical study of alcoholic fermentation. Joseph Louis Gay‐Lussac continued Lavoisier's research into the next century. As early as 1785, Adam Fabroni, an Italian scientist, was the first to provide an interpretation of the chemical composition of the ferment responsible for alcoholic fermentation, which he described as a plant–animal substance. According to Fabroni, this material, comparable to the gluten in flour, was located in special utricles, particularly on grapes and wheat, and alcoholic fermentation occurred when it came into contact with sugar in the must. In 1837, a French physicist named Charles Cagnard de La Tour proved for the first time that Yeast was a living organism. According to his findings, it was capable of multiplying and belonged to the plant kingdom; its vital activities were the basis for the fermentation of sugar‐containing liquids. The German naturalist Theodor Schwann confirmed his theory and demonstrated that heat and certain chemical products were capable of stopping alcoholic fermentation. He named the beer Yeast zuckerpilz, which means sugar fungus—Saccharomyces

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  Yeasts in Food

  • T Boekhout, V Robert(Authors)
  • 2003(Publication Date)
  • Woodhead Publishing

    (Publisher)

  11 Yeasts in bread and baking products BERNARD BONTEAN and LUC-DOMINIQUE GUILLAUME 11.1 Introduction A recent archaeological discovery showed that the ancient inhabitants of Asia Minor al- ready utilized Yeast as a fermentation agent. Saccharomyces cerevisiae is one of the best studied eukaryotes,both from academic and industrial points of view, and is the Yeast spe- cies used in the bakery. The publication of the complete genome of S. cerevisiae [22] strongly boosted the study and understanding of the cellular functions of this unicellular or- ganism. In this chapter we will review the use of Yeast in the bakery, and describe the in- dustrial production, the different types of Yeasts used by small and large-scale bakeries, the genetic improvementsobtained recently, and spoilage of baking products. 11.2 Properties of baking Yeast Leavening systems are used to raise bakery and pastry products. This can be achieved in several ways: a) By fermentation b) By decomposition of ammonium bicarbonate c) By a chemical reaction between a base and an acid d) By a change of the condition of water, for example in puff pastry (Fig. 11.2-1). e) By incorporation of air in the batter, for example in Biscuit-genoises. Sugar + Yeasts -+ ethanol + C02 + AW (energy) NH4HCO3 3 NH3 + H2O + C02 HX + NaHCO3 -+ NaX + H20 + COT 289 Propertiesof baksng Yeast I , I before baking during baking Fig. 11.2-1 The principle of pull pastry aeralion. In the aeration mechanism, the s¶eam is moving from the dough layer into the liquidfat layers,forcing the dough layers to separate and lift in the pastry. 11.2.1 Yeast in bread making process 1 1.2.1.1 In 1941, BAKER [S] performed comparative tests between stiff doughs packed in vacuum versus those kept in the open air. His results indicated that stiff doughs packed in vacuum resulted in a smaller volume of the baked product, a coarser structure of the soft part and a more intense coloration of the crust.

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  Brewing

  • Ian Hornsey(Author)
  • 2015(Publication Date)
  • Royal Society of Chemistry

    (Publisher)

  CHAPTER 5 Fermentation

  5.1 THE Yeast

  The most widely used Yeasts in the brewing industry are members of the fungal genus Saccharomyces , of which there are now nine defined species.1 Lodder2 defined Yeasts as “those fungi whose predominant growth form is unicellular”, a statement that implies, as is the case, that some species can produce transient filamentous (hyphal) outgrowths. Emil Hansen's first classification of Yeasts, which appeared around the dawn of the 20th century, only made a distinction between those that produced sexual spores, and those that did not (referred to as “sporogenous” and “asporogenous”, respectively). We now know that Hansen's sporogenous Yeasts belong to the phyla Ascomycota, and Basidiomycota, whilst the asporogenous forms are now classified as Fungi Imperfecti. Yeasts have been traditionally classified by means of conventional cultural techniques that determine a range of morphological, biochemical and physical properties. Criteria and methods for conducting such tests have been reviewed by Kreger-van Rij,3 and include: cell shape and size; sporulation; fermentation and assimilation of different sugars; assimilation of a nitrogen source; growth-factor requirement, and resistance to cycloheximide.

  Prior to nucleic acid studies becoming de rigueur , huge numbers of identification tests were employed (about sixty were used by Lodder2 ). Workload for such tests is demanding, and, in some cases, results for final identification may not be available for a fortnight. Progress in the development of simpler, more rapid methods was made during the late 1970s and the 1980s, and several easy-to-use diagnostic kits have been made available commercially. Such kits, however, are mainly applicable to a limited range of Yeasts of industrial and medical significance. James Barnett, whose text4 is fundamental, has produced an excellent review of Yeast taxonomy,5 , and appreciates the problems caused by continually changing names, particularly those faced by the brewer who still wants a new stock culture of Saccharomyces carlsbergensis ! To illustrate the problem, the fourth edition of The Yeasts: A Taxonomic Study 6 lists 98 synonyms for Saccharomyces cerevisiae

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  A Natural History of Beer

  • Rob DeSalle, Ian Tattersall, Patricia J. Wynne(Authors)
  • 2019(Publication Date)
  • (Publisher)

  Yeast 111 Some Yeasts have remained wild and have maintained a lot of genetic variability. Others have been captured—domesticated—and now be-have very differently from their wild progenitors. And because the cap-tive niches they live in are highly constrained, still others have evolved very specific responses to their circumstances. Along the way, beer Yeasts seem to have acquired two characteristics of domesticated organ-isms: extreme genome specialization, and extreme niche specialization. Fortunately enough variation remains, both inside the genus Saccharo-myces and outside it, to ensure that beer Yeast biology will remain inter-esting for as long as we brew beer. Finally, the latest wrinkle in the saga of Yeast and beer involves a radi-cal departure from tradition. Since the beginning, brewers have been restricted to making beer in batches. After fermentation is complete and the beer has been drawn off and bottled, the brewing equipment must be cleaned of both dead and living Yeasts so that the process can start all over again from scratch. But what if beer could be produced continuously, much as many spirits are nowadays? The University of Washington chemist Alshakim Nelson has proposed a way of doing this. Using three-dimensional printing techniques, his team has produced minute hydrogel bioreactors in which a population of Yeast can flour-ish and be active for months at a time. When these tiny Yeast-infused cubes are dropped into a glucose solution they set to work doing what Yeast do so well—fermenting it, in a process that continues for as long as the solution is replenished. Why the Yeast abandons its life-and-death cycle under these conditions is not yet known, but the possible implica-tions of this new approach for the future of brewing are intriguing, to say the least.

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  Bioethanol

  Biochemistry and Biotechnological Advances

  • Ayerim Y. Hernández Almanza, Nagamani Balagurusamy, Héctor Ruiz Leza, Cristóbal N. Aguilar(Authors)
  • 2022(Publication Date)
  • Apple Academic Press

    (Publisher)

  Finally, it is important to reaffirm the ability of Yeast cells to grow, metabolize complex industrial raw materials and withstand the hostile environments of large-scale fermenters. Throughout this chapter, important considerations of Yeast stress and nutritional physiology that influence Yeast fermenta-tive activities have been addressed. In addition to the Yeast optimization and improvement strategies used in alcohol production, it is a priority to know the Yeast strain to use in order to carry out the correct approach when carrying out the fermentation process. Even today, Yeasts continue to be one of the least understood organisms, and in the same way they are among the most important as input in ethanol production processes. Even so, under the correct conditions of both feeding and environment, it is currently possible to obtain volumes of more than 20% of ethanol production, when these conditions are not met, leading to stress in the lead, stuck, slow, and inefficient fermentations are obtained. Therefore, it is essential to optimize alcoholic fermentations to understand aspects of Yeast cell physiology, particularly when lignocellulosic substrates are used for the production of second-generation bioethanol.

  KEYWORDS

  • alcohol dehydrogenase
  • bioethanol production
  • biorefinery
  • growth conditions
  • lignocellulosic biomass
  • Yeast physiology

  REFERENCES

  1. Dzialo, M. C., Park, R., Steensels, J., Lievens, B., & Verstrepen, K. J. , (2017). Physiology, ecology, and industrial applications of aroma formation in Yeast. FEMS Microbiol. Rev. , 41, S95–S128. https://doi.org/10.1093/femsre/fux031 .
  2. Buzzini, P., (2006). Yeast biodiversity and biotechnology. Yeast Handbook; Biodivers. Ecophysiol. Yeasts , pp. 533–559. https://doi.org/10.1007/3–540–30985–3_22 .
  3. Van, D. S. P. , (2015). Approaches to production of natural flavors. In: Parker, J. K., Elmore, J. S., & Methven, L. B., (eds.), Flavor Development, Analysis and Perception in Food and Beverages (pp. 235–248). Woodhead Publishing. https://doi.org/https://doi.org/10.1016/B978–1–78242–103–0.00011–4 .
  4. Araújo, W. A. , (2016). Ethanol industry: Surpassing uncertainties and looking forward. In: Global Bioethanol.

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