Yeast Cell

10 Key excerpts on "Yeast Cell"

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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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  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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  Importance of Microbiology Teaching and Microbial Resource Management for Sustainable Futures

  • Ipek Kurtboke(Author)
  • 2022(Publication Date)
  • Academic Press

    (Publisher)

  Chapter 12: Yeast as a model organism for teaching biotechnology and human cell biology leading to sustainable futures

  Ian G. Macreadie      Honorary Professor of Biotechnology, School of Science, RMIT University, Melbourne, VIC, Australia

  Abstract

  In an age when resources are becoming increasingly scarce, it is important that educators can provide practical teaching exercises in a cost-effective mode that engages students, leaving a lasting impression that is relevant to their learning. Yeast can help to teach study about human biology, health and disease, as well as aid in the production of valuable resources, such as fermented beverages, vaccines and insulin. Yeast is the simplest eukaryote and its convenient, inexpensive and rapid culture, combined with easy genetic manipulation, means that it is ideal for teaching. Using yeast there are opportunities to teach about genetics, mutations, toxicology, drug mechanisms, biology, biotechnology and synthetic biology. This chapter provides a detailed account of how yeast can be used in teaching, using many personal examples, to provide valuable learning outcomes.

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  Handbook of Brewing

  • Graham G. Stewart, Inge Russell, Anne Anstruther, Graham G. Stewart, Inge Russell, Anne Anstruther(Authors)
  • 2017(Publication Date)
  • CRC Press

    (Publisher)

  9 in a recent review explore this topic of natural hybrids and the creation of new hybrids and further attempt to explain the complex history of brewing yeast and discuss future potential opportunities.

  For simplicity, brewing yeast will be referred to as S. cerevisiae throughout this chapter unless distinct reference is made to lager yeast.

  8.2 STRUCTURE OF YEAST

  The group of microorganisms known as “yeast” is by traditional agreement limited to fungi in which the unicellular form is predominant.10 Figure 8.1 shows the features of a typical Yeast Cell, and Figure 8.2 is an electron micrograph of a budding Yeast Cell.

  Figure 8.1 Main features of a typical Yeast Cell.

  Figure 8.2 Electron micrograph of budding Yeast Cell. (Courtesy of Alex Speers, Heriot-Watt University.)

  Yeasts vary in size, from roughly 5 μm to 10 μm in length to a breadth of 5 μm to 7 μm. The mean cell size varies with the growth cycle stage, fermentation conditions, and cell age (older cells are larger in size).

  8.2.1 Cell Wall

  The Yeast Cell wall is a multifunctional organelle of protection, shape, cell interaction, reception, attachment, and specialized enzymic activity. The cell wall, which is 100 nm to 200 nm thick, constitutes 15% to 25% of the dry weight of the cell and consists primarily of equal amounts of phosphomannan (31%) and glucans (29%). There are three glucans present in the wall (Figure 8.3 ).

  Figure 8.3 Simplified structure of the Yeast Cell wall and plasma membrane.

  The major component of the wall is an alkali-insoluble, acid-insoluble β-1,3-linked polymer, which helps the wall maintain its rigidity. There is an alkali-soluble branched glucan, with predominantly β-1,3-linkages, but with some β-1,6-linkages as well. The cell wall also contains a small portion of predominantly β-1,6-linked glucan. Chitin, a polymer of N-acetyl glucosamine, is present in small quantities (2% to 4%) and is almost always restricted to the bud scar. Mannans are present as an α-1,6-linked inner core with α-1,2- and α-1,3-side chains. Lipids are present at about 8.5% and proteins at about 13%. The carbohydrate portion of the mannoprotein on the Yeast Cell surface determines the immunochemical properties of the cell. The exact composition of the cell wall is dependent on growth conditions, age of the culture, and the specific yeast strain. The construction and structures of the Yeast Cell wall have been reviewed in detail by Klis et al.11

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  Handbook of Food Spoilage Yeasts

  • Tibor Deak(Author)
  • 2007(Publication Date)
  • CRC Press

    (Publisher)

  Only the most important morphological and physiological criteria that serve to identify foodborne yeasts are discussed here. Yeast classification is changing, and now based on molecular characteristics. Trends and recent developments in this field will be summarized as well. TABLE 1.1 Criteria Traditionally Used in the Characterization of Yeasts Morphological Physiological Biochemical, Molecular Sexual reproduction Fermentation of sugars Diazonium Blue B reaction Mode of conjugation Assimilation of carbon sources Urease reaction Forms of spores and sporangia Assimilation of nitrogen sources Type of coenzyme Q Formation of basidiospores Vitamin requirements Cell wall composition Vegetative reproduction Temperature of growth Whole-cell carbohydrates Budding Growth at low water activity Long-chain fatty acids Fission Resistance to cycloheximide Protein electrophoretic pattern Arthroconidia Formation of starch Isoenzymes Ballistoconidia Production of acetic acid Microscopic growth Guanine + cytosine mol% Size and shape of cells DNA–DNA homology True hyphae and pseudohyphae DNA restriction fragments Chlamydospores Gene probes Macroscopic growth Chromosome karyotyping Colonies on solid media rDNA sequences Liquid cultures Complete sequences 1 2 Handbook of Food Spoilage Yeasts 1.1 MORPHOLOGICAL AND PHYSIOLOGICAL CHARACTERISTICS For practical purposes, yeasts may be defined as unicellular fungi, in which the vegetative (asexual) reproduction occurs mainly by budding. According to terminology introduced for fungi (von Arx, 1979), budding is a type of conidiation and the buds are blastoconidia. The large majority of yeasts (e.g., Saccharomyces ) exhibit multilateral budding, a special type of cell division in which daughter cells (buds) appear over a large area of the cell surface. In contrast, in bipolar budding, the buds are formed only at the poles of the cells (annelloconidiation), resulting in characteristic lemon-shaped cells (e.g., Hanseniaspora ; Figure 1.1).

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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)

  Certain multicellular fungi have a single‐celled stage and are also grouped with yeasts. Yeasts form a complex and heterogeneous group found in three classes of fungi, characterized by their reproduction mode: Ascomycetes, Basidiomycetes, and the imperfect fungi (Deuteromycetes). However, yeasts found on the surface of the grape and in wine belong only to Ascomycetes and the imperfect fungi. The haploid spores or ascospores of the Ascomycetes class are contained in the ascus, a type of sac made from vegetative cells. Asporogenous yeasts, incapable of sexual reproduction, are classified with the imperfect fungi. In this chapter, the morphology, reproduction, taxonomy, and ecology of grape and wine yeasts will be discussed. Cytology is the morphological and functional study of the structural components of the cell (Rose and Harrison, 1991). Yeasts are the most simple of the eukaryotes. The Yeast Cell contains cell envelopes, a cytoplasm with various organelles, and a nucleus surrounded by a membrane and enclosing the chromosomes (Figure 1.1). Like all plant cells, the Yeast Cell has two cell envelopes: the cell wall and the plasma membrane. The periplasmic space is the space between the cell wall and the membrane. The cytoplasm and the membrane make up the protoplasm. The terms protoplast and spheroplast designate a cell whose cell wall has been “artificially” removed in full or in part, respectively. Yeast Cell envelopes play an essential role: they contribute to a successful alcoholic fermentation of must and release certain constituents that add to the resulting wine's composition

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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)

  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. Each group is termed a taxon. In descending order of hierarchy the main taxonomic groups are kingdom, division, class, order, family, genus, species and strain. Of these, the last three are of most practical interest. A genus represents a group of organisms, which are closely related in evolutionary terms. Usually this is accompanied by structural and functional similarities. Organisms are grouped into species usually based on the ability to interbreed. In the case of yeast, many of which have no sexual cycle, this definition is of limited value. Where organisms are restricted to asexual reproduction, placement within a species has to be based on other criteria, the most reliable being that of similarity of genotype. Strains are clones derived from a single parental cell. For example, in the case of yeast a cell line propagated from a single colony of a pure culture

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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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  Biodegradation, Pollutants and Bioremediation Principles

  • Ederio Dino Bidoia, Renato Nallin Montagnolli, Ederio Dino Bidoia, Renato Nallin Montagnolli(Authors)
  • 2021(Publication Date)
  • CRC Press

    (Publisher)

  Microencapsulation is a process of covering active compounds or living microorganisms by a carrier material for various proposes, such as stabilizing the active compounds, extending the shelf-life, and protecting them from micro-environments. The optimum release of components is another benefit of this process. It is applied in many fields of sciences and different industries, including pharmaceuticals, cosmetic, and food industries (Madene et al. 2006, Schrooyen et al. 2001).

  The Yeast Cell of Saccharomyces cerevisiae is one of the most important one, which has been used from about 50 years ago as an encapsulation coating material for essential oils and flavors (NA 1990). Being natural causes many advantages over the other microencapsulation carriers (Nelson 2002). It is present in human nutrition (generally recognized as safe, GRAS) with low cost. It is shown that the fungal cell wall with a dynamic structure protects the cell from environmental stresses, including changes in osmotic pressure. However, it allows the cell to interact with its surrounding environment (Bowman and Free 2006). Nowadays, technologists have incorporated several compounds with different physicochemical (hydrophobic/ hydrophilic) properties in the Yeast Cells (Bishop et al. 1998, Mokhtari et al. 2017b, Nelson 2002, Paramera et al. 2011a, Pham-Hoang et al. 2013).

  _______________

  1 Department of Pharmaceutical Control, School of Pharmacy, Mashhad University of Medical Sciences. Vakilabad Blvd, Mashhad, +9851, Iran

  2 Department of Pharmaceutical Control, School of Pharmacy/Biotechnology Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences Vakilabad Blvd, Mashhad, +9851, Iran

  3 Department of Food Hygiene, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad Vakilabad Blvd, Mashhad, +9851, Iran

  * Corresponding author: [email protected]

  The structure of this carrier is composed of the water soluble 0-1,3 and 0-1,6 D-glucans, the major polysaccharides of the Yeast Cell walls. These structures have a wide range of important properties, including antibacterial activities, wound-healing, antioxidant, anti-mutagenic, and anti-genotoxic properties, which make them potent agents for application in anti-infective and anti-cancer therapies (Kogan et al. 2008).

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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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