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Can Glucose Be Fermented By Yeast?

Switching The Mode Of Metabolism In The Yeast Saccharomyces Cerevisiae

Switching The Mode Of Metabolism In The Yeast Saccharomyces Cerevisiae

Switching the mode of metabolism in the yeast Saccharomyces cerevisiae We are experimenting with display styles that make it easier to read articles in PMC. The ePub format uses eBook readers, which have several "ease of reading" features already built in. The ePub format is best viewed in the iBooks reader. You may notice problems with the display of certain parts of an article in other eReaders. Generating an ePub file may take a long time, please be patient. The European Molecular Biology Organization Switching the mode of metabolism in the yeast Saccharomyces cerevisiae Karin Otterstedt, Christer Larsson, [...], and Lena Gustafsson The biochemistry of most metabolic pathways is conserved from bacteria to humans, although the control mechanisms are adapted to the needs of each cell type. Oxygen depletion commonly controls the switch from respiration to fermentation. However, Saccharomyces cerevisiae also controls that switch in response to the external glucose level. We have generated an S. cerevisiae strain in which glucose uptake is dependent on a chimeric hexose transporter mediating reduced sugar uptake. This strain shows a fully respiratory metabolism also at high glucose levels as seen for aerobic organisms, and switches to fermentation only when oxygen is lacking. These observations illustrate that manipulating a single step can alter the mode of metabolism. The novel yeast strain is an excellent tool to study the mechanisms underlying glucose-induced signal transduction. Keywords: metabolism, respiration, hexose transport, glycolysis, signalling The glycolytic pathway and its individual enzymes are conserved during evolution, although mechanisms controlling carbon and energy metabolism have adapted to the needs of each species or cell type. Aerobic organisms Continue reading >>

Fermented And Vegetables. A Global Perspective. Chapter 3.

Fermented And Vegetables. A Global Perspective. Chapter 3.

A yeast is a unicellular fungus which reproduces asexually by buddingor division, especially the genus Saccharomyces which is important in foodfermentations (Walker, 1988). Yeasts and yeast-like fungi are widely distributed innature. They are present in orchards and vineyards, in the air, the soil and theintestinal tract of animals. Like bacteria and moulds, they can have beneficial andnon-beneficial effects in foods. Most yeasts are larger than most bacteria. The most wellknown examples of yeast fermentation are in the production of alcoholic drinks and theleavening of bread. For their participation in these two processes, yeasts are of majorimportance in the food industry. Some yeasts are chromogenic and produce a variety of pigments,including green, yellow and black. Others are capable of synthesising essential B groupvitamins. Although there is a large diversity of yeasts and yeast-like fungi,(about 500 species), only a few are commonly associated with the production of fermentedfoods. They are all either ascomycetous yeasts or members of the genus Candida.Varieties of the Saccharomyces cervisiae genus are the most common yeasts infermented foods and beverages based on fruit and vegetables. All strains of this genusferment glucose and many ferment other plant derived carbohydrates such as sucrose,maltose and raffinose. In the tropics, Saccharomyces pombe is the dominantyeast in the production of traditional fermented beverages, especially those derived frommaize and millet (Adams and Moss, 1995). 3.2 Conditions necessary for fermentation Most yeasts require an abundance of oxygen for growth, therefore bycontrolling the supply of oxygen, their growth can be checked. In addition to oxygen, theyrequire a basic substrate such as sugar. Some yeasts can ferment sugars to Continue reading >>

Ep2627765a2 - Pentose And Glucose Fermenting Yeast Cell - Google Patents

Ep2627765a2 - Pentose And Glucose Fermenting Yeast Cell - Google Patents

EP2627765A2 - Pentose and glucose fermenting yeast cell - Google Patents Pentose and glucose fermenting yeast cell EP2627765A2 EP11767263.4A EP11767263A EP2627765A2 EP 2627765 A2 EP2627765 A2 EP 2627765A2 EP 11767263 A EP11767263 A EP 11767263A EP 2627765 A2 EP2627765 A2 EP 2627765A2 Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.) Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.) Priority to US39261710P priority Critical Application filed by DSM IP Assets BV filed Critical DSM IP Assets BV Priority to PCT/EP2011/067720 priority patent/WO2012049170A2/en Priority to EP11767263.4A priority patent/EP2627765B1/en Publication of EP2627765A2 publication Critical patent/EP2627765A2/en Publication of EP2627765B1 publication Critical patent/EP2627765B1/en Application status is Active legal-status Critical C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING C12NMICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA C12N15/00Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor C12N15/63Introduction of foreign genetic material using vectors; Vectors; Use of hosts therefor

Ethanol Fermentation

Ethanol Fermentation

In ethanol fermentation, (1) one glucose molecule breaks down into two pyruvates. The energy from this exothermic reaction is used to bind the inorganic phosphates to ADP and convert NAD+ to NADH. (2) The two pyruvates are then broken down into two acetaldehydes and give off two CO2 as a by-product. (3) The two acetaldehydes are then converted to two ethanol by using the H- ions from NADH, converting NADH back into NAD+. Ethanol fermentation, also called alcoholic fermentation, is a biological process which converts sugars such as glucose, fructose, and sucrose into cellular energy, producing ethanol and carbon dioxide as by-products. Because yeasts perform this conversion in the absence of oxygen, alcoholic fermentation is considered an anaerobic process. It also takes place in some species of fish (including goldfish and carp) where (along with lactic acid fermentation) it provides energy when oxygen is scarce.[1] Ethanol fermentation has many uses, including the production of alcoholic beverages, the production of ethanol fuel, and bread cooking. Biochemical process of fermentation of sucrose[edit] A laboratory vessel being used for the fermentation of straw. Fermentation of sucrose by yeast. The chemical equations below summarize the fermentation of sucrose () into ethanol (). Alcoholic fermentation converts one mole of glucose into two moles of ethanol and two moles of carbon dioxide, producing two moles of ATP in the process. The overall chemical formula for alcoholic fermentation is: Sucrose is a dimer of glucose and fructose molecules. In the first step of alcoholic fermentation, the enzyme invertase cleaves the glycosidic linkage between the glucose and fructose molecules. Next, each glucose molecule is broken down into two pyruvate molecules in a process known Continue reading >>

The Fermentation Of Fructose In Wine Making

The Fermentation Of Fructose In Wine Making

The fermentation of fructose in wine making 1939 vues - 6 juin 2018 - Publi par Lallemand Oenologie Glucose and fructose are the main fermentable sugars in wine must. During alcoholic fermentation, wine yeasts convert most of the glucose and fructose present into alcohol and CO2. Selected yeasts differ in their capacity to consume fructose and can have an important impact on the fermentation performance, especially under difficult conditions. The fructophilic index of wine yeast appears as a good indicator of performance in potentially problematic fermentation conditions. Fructose is a 6-carbon polyhydroxyketone. It is an isomer of glucose; i.e.,both have the same molecular formula (C6H12O6) but they differ structurally.It is one of the sugars consumed by yeast during wine fermentation. Glucose and fructose are the main fermentable sugars in wine must.During alcoholic fermentation, yeasts convert most of the glucose and fructose present intoalcohol and CO2. Grape musts contain equal amounts of glucose and fructose, and their totalconcentrations typically range from 160 to 300 g/liter. Saccharomyces cerevisiae is a glucophilic yeast, preferring glucose to fructose. During fermentation,glucose is consumed at a higher rate than fructose, and the proportion of fructose increasesas fermentation progresses. This can lead to imbalances in the wines, and under thestressful conditions found at the end of fermentation, make it more difficult for wine yeast toutilize this non-preferred sugar. Therefore, knowing how the fructose utilization varies in wineyeasts is important for the maintenance of a steady fermentation rate at the end of alcoholicfermentation and limit the risk of stuck fermentation. What are the factors influencing fructose utilization during fermentation ? During Continue reading >>

Sugars For Fermentation| Brewery Lane

Sugars For Fermentation| Brewery Lane

Many sugars can be used for fermentation. They all have specific characteristics that will have an effect on the taste and mouthfeel of your brew. Here is an outline of the most common sugars used in brewing. Glucose is a monosaccharide. This simple sugar is derivable from converted starches such as what happens when mashing malted grain. Sugar processors can make this sugar from a variety of sourcescorn (maize), wheat, rice, potatoes, in short, anything with cheap starch can be an input into the process. However if not completely refined down to simple sugars, some of the origin can be discerned. The right-handed variation of glucose is called dextrose. A disaccharide made up of two glucose molecules. Completely fermentable. Contributes 45 points of specific gravity per pound. Another monosaccharide. In all-malt beers, this normally appears as only a few percent of the wort. Yeasts will rapidly ferment this but there might be some off-flavour problems if used in brewing beer. Fructose tastes much sweeter than glucose or even the combination of fructose + glucose (= sucrose). That's why big food processing companies use "high fuctose" sugars because they get more bang for the buck by using less of a sweeter tasting sugar. See the entry for "sucrose" for a description of how the "high fructose" syrup is made. Sucrose is a disaccharide composed of one molecule of glucose and one of fructose. More precisely, it is dextrose plus dextrorotary fructose. It must be broken apart before the yeasts can use it. When heated in an acidic solution (such as wort) the sugar is inverted to make glucose and fructose. Yeasts will invert the sucrose if it is not already in that form before using by using invertase. It is derived from sugar beets or sugar cane that are crushed and dissolve Continue reading >>

Ethanol Fermentation

Ethanol Fermentation

Shang-Tian Yang, ... Yali Zhang, in Bioprocessing for Value-Added Products from Renewable Resources , 2007 Ethanol fermentation is one of the oldest and most important fermentation processes used in the biotechnology industry. In the U.S. alone, about 4.5 billion gallons of ethanol are produced annually from corn and used as a transportation fuel. The annual production of bioethanol in the U.S. is expected to grow to more than 7.5 billion gallons in the next few years and reach 30 billon gallons by 2025. Many microorganisms, including bacteria and yeasts, can produce ethanol as the major fermentation product from carbohydrates [123]. Current industrial ethanol fermentation is mainly carried out with the yeast Saccharomyces cerevisiae because of its hardiness (low pH and high ethanol tolerance), although the bacterium Zymomonas mobilis has a higher specific ethanol productivity and yield from glucose and sucrose. Metabolic engineering of S. cerevisiae, Z. mobilis, and E. coli for improved ethanol fermentation has been extensively studied [124128]. Most efforts have been focused on the creation of efficient xylose-fermenting mutant strains because neither S. cerevisiae nor Z. mobilis can use xylose, which is the second most abundant sugar (next to glucose) present in plant biomass (hemicellulose). Since yeasts can grow on and ferment xylulose, the heterologous expression of bacterial xylose isomerase (XI) appeared to be a reasonable approach to engineer S. cerevisiae for xylose assimilation. However, all earlier efforts using this approach failed even though the cloned gene XylA from Thermus thermophilus and Piromyces sp E2 produced active xylose isomerase in S. cerevisiae. The failure was partially because xylose isomerase is strongly inhibited by xylitol and the isomer Continue reading >>

Yeast, Fermentation, Beer, Wine | Learn Science At Scitable

Yeast, Fermentation, Beer, Wine | Learn Science At Scitable

Figure 1:Fermented beverages such as wine have been produced by different human cultures for centuries. Christian Draghici/Shutterstock. All rights reserved. In the seventeenth century, a Dutch tradesman named Antoni van Leeuwenhoek developed high-quality lenses and was able to observe yeast for the first time. In his spare time Leeuwenhoek used his lenses to observe and record detailed drawings of everything he could, including very tiny objects, like protozoa, bacteria, and yeast. Leeuwenhoek discovered that yeast consist of globules floating in a fluid, but he thought they were merely the starchy particles of the grain from which the wort (liquid obtained from the brewing of whiskey and beer) was made (Huxley 1894). Later, in 1755, yeast were defined in the Dictionary of the English Language by Samuel Johnson as "the ferment put into drink to make it work; and into bread to lighten and swell it." At the time, nobody believed that yeast were alive; they were seen as just organic chemical agents required for fermentation. In the eighteenth and nineteenth centuries, chemists worked hard to decipher the nature of alcoholic fermentation through analytical chemistry and chemical nomenclature. In 1789, the French chemist Antoine Lavoisier was working on basic theoretical questions about the transformations of substances. In his quest, he decided to use sugars for his experiments, and he gained new knowledge about their structures and chemical reactions. Using quantitative studies, he learned that sugars are composed of a mixture of hydrogen, charcoal (carbon), and oxygen. Lavoisier was also interested in analyzing the mechanism by which sugarcane is transformed into alcohol and carbon dioxide during fermentation. He estimated the proportions of sugars and water at the begi Continue reading >>

Sugar Utilization By Yeast During Fermentation

Sugar Utilization By Yeast During Fermentation

, Volume 4, Issue4 , pp 315323 | Cite as Sugar utilization by yeast during fermentation When glucose and fructose are fermented separately, the uptake profiles indicate that both sugars are utilized at similar rates. However, when fermentations are conducted in media containing an equal concentration of glucose and fructose, glucose is utilized at approximately twice the rate of fructose. The preferential uptake of glucose also occurred when sucrose, which was first rapidly hydrolyzed into glucose and fructose by the action of the enzyme invertase, was employed as a substrate. Similar results were observed in the fermentation of brewer's wort and wort containing 30% sucrose and 30% glucose as adjuncts. In addition, the high levels of glucose in the wort exerted severe catabolite repression on maltose utilization in theSaccharmyces uvarum (carlsbergensis) brewing strain. Kinetic analysis of glucose and fructose uptake inSaccharomyces cerevisiae revealed aKm of 1.6 mM for glucose and 20 mM for fructose. Thus, the yeast strain has a higher affinity for glucose than fructose. Growth on glucose or fructose had no repressible effect on the uptake of either sugar. In addition, glucose inhibited fructose uptake by 60% and likewise fructose inhibited, glucose uptake by 40%. These results indicate that glucose and fructose share the same membrane transport components. This is a preview of subscription content, log in to check access Unable to display preview. Download preview PDF. Bisson, L.F. and D.G. Fraenkel. 1983. Involvement of kinases in glucose and fructose uptake bySaccharomyces cerevisiae. Proc. Natl. Acad. Sci. U.S.A. 80: 17301734. Google Scholar Bisson, L.F. and D.G. Fraenkel. 1984. Expression of kinasedependent glucose uptake inSaccharomyces cerevisiae. J. Bacteriol. Continue reading >>

How Does Sugar Affect Yeast Growth?

How Does Sugar Affect Yeast Growth?

Yeast is a fungus and needs a supply of energy for its living and growth. Sugar supplies this energy (your body also gets much of its energy from sugar and other carbohydrates). Yeast can use oxygen to release the energy from sugar (like you can) in the process called "respiration". So, the more sugar there is, the more active the yeast will be and the faster its growth (up to a certain point - even yeast cannot grow in very strong sugar - such as honey). However, if oxygen is short (like in the middle of a ball of dough), then yeast can still release energy from sugar, but in these conditions, its byproducts are alcohol and carbon dioxide. It is this carbon dioxide gas which makes the bubbles in dough (and therefore in bread), causing the dough to rise. Alcohol is a poison (for yeast as well as for people) and so the yeast is not able to grow when the alcohol content gets too high. This is why wine is never more than about 12% alcohol. WHY does an excess of sugar inhibit the yeast? My guess would be that the osmotic concentration of the sugar gets so great that the yeast is unable to get enough water for growth. As fresh yeast is more than 90% water, the single substance most needed for growth is water. As osmotic concentration increases, the water potential of the sugar solution gets more and more negative until it reaches a point where is lower than the water potential of the yeast cell contents and water tends to move OUT of the cell rather than IN. I do not know whether yeast cells are able to take up water actively, by expenditure of metabolic energy to pump the water against the water potential gradient. I imagine that up to a certain concentration, the limiting factor is the amount of sugar available for respiration and synthesis of cell materials with the yeas Continue reading >>

Yeast Respiration

Yeast Respiration

Students are often confused by the term isomer. Eventually, they memorize a definition and know that isomers share atomic composition, but vary in their structures. What are the consequences for organisms? Can organisms use any molecule for energy as long as they have the same chemical formulas? Or does the structure of each molecule affect the usefulness of a molecule? In this investigation, it is determined that not all sugar is the same. Only certain configurations of sugar molecules can be used by yeast. Three Monomers Shown Below--Three Dimers Shown Above 1. The fundamental life processes of plants and animals depend on a variety of chemical reactions that occur in specialized areas of the organisms cells. As a basis for understanding this concept: b. Students know enzymes are proteins that catalyze biochemical reactions without altering the reaction equilibrium and the activities of enzymes depend on the temperature, ionic conditions, and the pH of the surroundings. g. Students know the role of the mitochondria in making stored chemical-bond energy available to cells by completing the breakdown of glucose to carbon h. Students know most macromolecules (polysaccharides, nucleic acids, proteins, lipids) in cells and organisms are synthesized from a small collection of simple 1. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other four strands, students should develop their own questions and perform d. Formulate explanations by using logic and evidence. Fill the six eudiometers with colored tap water (colored water is easier to read). Invert each in a 600mL or larger beaker on a ring stand. Create 10% solutions of each of the six sugars. (ad Continue reading >>

Fermentation Of Glucose Using Yeast

Fermentation Of Glucose Using Yeast

Fermentation of glucose using yeast Class practical Beer and wine are produced by fermenting glucose with yeast. Yeast contains enzymes that catalyse the breakdown of glucose to ethanol and carbon dioxide. In this experiment, a glucose solution is left to ferment. Students then test for fermentation products. Lesson organisation This experiment takes time. The solution needs to ferment between lessons, especially if you are distilling the final solution to produce ethanol. Apparatus Chemicals Eye protection Each pair of students requires: Conical flask (100 cm3) Boiling tube Measuring cylinder (50 cm3) Access to a balance (1 d.p) Cotton wool Sticky labels Warm water 30–40 °C (Note 1) Glucose, 5 g Yeast (as fast acting as possible), 1 g Limewater Refer to Health & Safety and Technical notes section below for additional information. Health & Safety and Technical notes Wear eye protection. Glucose C6H12O6(s) - see CLEAPSS Hazcard. Limewater, Ca(OH)2(aq) – a saturated solution of calcium hydroxide in water - see CLEAPSS Hazcard and Recipe book. 1 A source of warm water is required. Larger conical flasks can be used, but this dilutes the carbon dioxide concentration, and makes testing for carbon dioxide with limewater more difficult. Procedure Lesson 1 a Put 5 g of glucose in the conical flask and add 50 cm3 of warm water. Swirl the flask to dissolve the glucose. b Add 1 g of yeast to the solution and loosely plug the top of the flask with cotton wool. c Wait while fermentation takes place. d Remove the cotton wool and pour the invisible gas into the boiling tube containing limewater. Take care not to pour in any liquid as well. f Replace the cotton wool in the top of the flask. Lesson 2 a Remove the cotton wool and note the smell of the solution. b The solution may be Continue reading >>

The Biochemistry Of Yeast

The Biochemistry Of Yeast

Debunking the Myth of Yeast Respiration and Putting Oxygen in Its Proper Place Originally Published by Tracy Aquilla in Brewing Techniques (Volume 5, Number 2) Through it flies in the face of popular wisdom, yeast does not go through a respiration phase in the early stages of fermentation. A careful look at yeast metabolism and reproduction reveals a common misunderstanding and points the way to more sophisticated applications of oxygen in the brewery. Fermentation is perhaps the most interesting and exciting part of brewing beer. There is something fascinating about watching yeast in action, and being close to the process contributes immensely to my enjoyment of my beer. No matter how well we do our part in preparing bitter wort for fermentation, it is the yeast that turns it into beer. For this reason alone, it is important to understand and appreciate what these microorganisms are really doing inside our fermentors. Most of the popular brewing literature, however, fosters a misconception about yeast and fermentation. This articles sets the record straight. Most of the brewing literature indicates that brewers yeast (Saccharomyces cerevisiae and S. uvarum) required dissolved oxygen for a brief period of time after pitching so the cells can respire and grow, implying that yeast needs oxygen to bud and must respire before it can ferment wort. It is true that aerating or oxygenating wort is generally beneficial to fermentation, but it is untrue to say that yeast requires oxygen to reproduce or that yeast uses oxygen to respire during fermentation. The misunderstanding may be subtle, but it is a misunderstanding nonetheless. Gaining a clear understanding of the truth about how yeast works not only sets us on sound technical foundations, but has practical applications as Continue reading >>

What Is Fermentation? Definition And Examples

What Is Fermentation? Definition And Examples

Some industrial alcohol production, such as for biofuels Yeast and certain bacteria perform ethanol fermentation where pyruvate (from glucose metabolism) is broken into ethanol and carbon dioxide . The net chemical equation for the production of ethanol from glucose is: C6H12O6 (glucose) 2 C2H5OH (ethanol) + 2 CO2 (carbon dioxide) Ethanol fermentation has used the production of beer, wine, and bread. It's worth noting that fermentation in the presence of high levels of pectin results in the production of small amounts of methanol, which is toxic when consumed. The pyruvate molecules from glucose metabolism (glycolysis) may be fermented into lactic acid. Lactic acid fermentation is used to convert lactose into lactic acid in yogurt production. It also occurs in animal muscles when the tissue requires energy at a faster rate than oxygen can be supplied. The next equation for lactic acid production from glucose is: C6H12O6 (glucose) 2 CH3CHOHCOOH (lactic acid) The production of lactic acid from lactose and water may be summarized as: C12H22O11 (lactose) + H2O (water) 4 CH3CHOHCOOH (lactic acid) The process of fermentation may yield hydrogen gas and methane gas. Methanogenic archaea undergo a disproportionation reaction in which one electron is transferred from a carbonyl of a carboxylic acid group to a methyl group of acetic acid to yield methane and carbon dioxide gas. Many types of fermentation yield hydrogen gas. The product may be used by the organism to regenerate NAD+ from NADH. Hydrogen gas may be used as a substrate by sulfate reducers and methanogens. Humans experience hydrogen gas production from intestinal bacteria, producing flatus . Fermentation is an anaerobic process, meaning it does not require oxygen in order to occur. However, even when oxygen is abundan Continue reading >>

Alcoholic Fermentation By Yeast Cells

Alcoholic Fermentation By Yeast Cells

[Lactic acid fermentation by lactic bacteria] In brewing, alcoholic fermentation is the conversion of sugar into carbon dioxide gas (CO2) and ethyl alcohol. This process is carried out by yeast cells using a range of enzymes. This is in fact a complex series of conversions that brings about the conversion of sugar to CO2 and alcohol. Yeast is a member of the fungi family which I like to think of as plants but strictly they are neither plant nor animal. To be specific yeast is a eukaryotic micro-organism. Not all yeasts are suitable for brewing. In brewing we use the sugar fungi form of yeast. These yeast cells gain energy from the conversion of the sugar into carbon dioxide and alcohol. The carbon dioxide by-product bubbles through the liquid and dissipates into the air. In confined spaces the carbon dioxide dissolve in the liquid making it fizzy. The pressure build up caused by C02 production in a confined space can be immense. Certainly enough to cause the explosion of a sealed glass bottle. Alcohol is the other by-product of fermentation. Alcohol remains in the liquid which is great for making an alcoholic beverage but not for the yeast cells, as the yeast dies when the alcohol exceeds its tolerance level. The overall process of fermentation is to convert glucose sugar (C6H12O6) to alcohol (CH3CH2OH) and carbon dioxide gas (CO2). The reactions within the yeast cell which make this happen are very complex but the overall process is as follows: C6H12O6 ====> 2(CH3CH2OH) + 2(CO2) + Energy (which is stored in ATP) Sugar ====> Alcohol + Carbon dioxide gas + Energy From the above it seems nice an simple chemistry one mole of glucose is converted into two moles of ethanol and two moles of carbon dioxide but in reality it is far from this clear. There are many by products. Continue reading >>

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