Showing papers on "Yeast published in 1982"

Synthesis and assembly of hepatitis B virus surface antigen particles in yeast

Abstract: The surface antigen of hepatitis B virus (HBsAg) has been synthesized in the yeast Saccharomyces cerevisiae by using an expression vector that employs the 5′-flanking region of yeast alcohol dehydrogenase I as a promoter to transcribe surface antigen coding sequences. The protein synthesized in yeast is assembled into particles having properties similar to the 22-nm particles secreted by human cells.

Preparation of hepatitis b surface antigen in yeast

Abstract: Hepatitis surface antigen is synthesized in recombinant yeast hosts transformed with vectors encoding hepatitis surface antigen, preferably under the control of the yeast PGK promoter and preferably in the absence of DNA encoding the surface antigen precursor. Hepatitis surface antigen is assembled by yeast into antigenic 22 nm particles even though hepatitis surface antigen bacterial transformants were not known to be capable of assembling the surface antigen into 22 nm particles.

Conservation of high efficiency promoter sequences in Saccharomyces cerevisiae.

Abstract: The position of the yeast phosphoglycerate kinase (PGK) gene has been mapped on a 2.95kb Hind III fragment. We have determined the nucleotide sequence of the 5' flanking region and compared this sequence with those from 16 other yeast genes. PGK, like all other yeast genes has an adenine residue at position -3. It has two possible TATA boxes at positions -114 and -152 and a CAAT box at -129. In addition we have defined a structure at position -63 to -39 that is common to all yeast genes that encode an abundant RNA. This structure is a CT-rich block followed, about 10 nucleotides later, by the sequence CAAG.

Lethal disruption of the yeast actin gene by integrative DNA transformation

Abstract: A mutant allele of the chromosomal locus corresponding to the cloned actin gene of the yeast Saccharomyces cerevisiae has been constructed by DNA transformation with a hybrid plasmid which integrates into, and thereby disrupts, the protein-encoding sequences of the gene. In a diploid strain of yeast, disruption of the actin gene on one chromosome results in a mutation that segregates as a recessive lethal tightly linked to a selectable genetic marker on the integrated plasmid. The actin gene, therefore, must encode an essential function for yeast cell growth.

Conversion of d-xylose to ethanol by the yeast pachysolen tannophilus

Abstract: A method has been discovered for converting D-xylose to ethanol relying on the unique ability of the yeast Pachysolen tannophilus to ferment this five-carbon sugar without the use of added enzymes. This process will be particularly useful in the production of ethanolic fuel from plant biomass.

Nitrogen Metabolism in Saccharomyces cerevisiae

Abstract: INTRODUCTION In decaying fruit and vegetable matter, which form their wild habitat, yeast cells encounter a broad spectrum of compounds able to serve as nitrogen sources. These materials range from simple ammonia and amino acids to complex nucleic acids and their derivatives. In response to this heterogeneous environment, Saccharomyces cerevisiae has evolved equally broad degradative enzyme systems and sophisticated ways of regulating and integrating their operation.1 In the past, enteric bacteria have served as a model for viewing the control of nitrogen metabolism in yeast. As a starting point, these past paradigms have served us well. However, they are certain to be inadequate for the future. An important area of deficiency is their failure to involve the complex internal structure of a yeast cell in the control and integration of nitrogen metabolism. Ignoring such structure and its potential role in cellular homeostasis may mortgage our understanding of a yeast cell’s ability to cope with a constantly changing environment. A SUMMARY OF THE MAJOR CATABOLIC SYSTEMS As shown in Table 1, S. cerevisiae will grow fairly well on many amino acids, uracil, purine derivatives, urea, and ammonia. Sometimes the cells go through only one or two generations (this is indicated in Table 1) before growth ceases. In these cases, the conclusion that cells are able to use the compound effectively must be viewed skeptically. However, in other cases, steady-state growth can easily be maintained. Only a limited number of these compounds and their metabolic fates have been studied; they are briefly...

Ethanol production by extractive fermentation

Abstract: The ideal method to produce a terminal metabolite inhibitor of cell growth and production is to remove and recover it from the fermenting broth as it formed. Extractive fermentation is achieved in the case of ethanol production by coupling both fermentation and liquid-liquid extraction, The solvent of extraction is 1-dodecanol (or a mixture 1-dedecanol, 1-tetradecanol); study of the inhibitory effect of primary aliphatic alcohols of different chain lengths shows that no growth is observed in the presence of alcohols which have between 2 and 12 carbons. This effect is suppressed when the carbon number is 12 or higher. A new reactor has been used-1 pulsed packed column. Pulsation is performed pneumatically. Porous material used as a package adsorbs the cells. The fermentation broth is pulsed in order to (1) increase the interfacial area between the aqueous phase and the dodecanol, (2) decrease gas holdup. Alcoholic fermentation, performed at 35 degrees C on glucose syrup, permits the total utilization of glucose solution of 409 g/L with a yeast which cannot-in classical process- completely use solutions with 200 g/L of glucose. The feasibility of a new method of fermentation coupling both liquid-liquid extraction and fermentation is demonstrated. Extension of this method is possible to any microbial production inhibited by its metabolite excretion.

Mechanisms of solute transport in selected eukaryotic micro-organisms.

Abstract: Publisher Summary This chapter considers the chemiosmotic interpretation of the synthesis of ATP, which takes place in the mitochondria and chloroplasts of eukaryotic micro-organisms The evidence that is available indicates that the ionic pumps of the plasma membranes of these organisms are not involved in ATP synthesis Thus the plasma membrane of yeast lacks a typical electron-transport chain, resembling in this respect the plasma membrane of anaerobic organisms such as Streptococcus faecalis rather than the plasma membrane of facultative aerobes like Escherichia coli, which carry out oxidative phosphorylation It discusses that a further comparison concerns the extensively studied transport systems of mammalian cells, which include the sodium pump based on a Na/K-ATPase A wide range of such cells involve Na + ions in secondary active transport of various carbohydrates and amino acids Similar coupled mechanisms are found in certain bacteria Their occasional occurrences in eukaryotic microorganisms are also considered in this chapter

Expression of polypeptides in yeast

Abstract: DNA expression vectors capable, in a transformant strain of yeast, of expressing a polypeptide under the control of a genetically distinct yeast promoter, processes of forming transformant strains of yeast and transformed yeast strains are disclosed

Regulated high efficiency expression of human interferon-alpha in Saccharomyces cerevisiae.

Abstract: The 5' control region of the yeast phosphoglycerate kinase gene (PGK) was fused to the coding sequence of a human interferon-alpha. This PGK-interferon fusion was then introduced into yeast on a high copy number 2mu-based plasmid vector. Strains containing this plasmid produced a PGK-interferon-alpha fusion protein as 1-2% of cell protein and the expression of interferon activity was regulated by the availability of a fermentable carbon source. The system is capable of making as much as 15 mg of human interferon-alpha per litre of batch culture.

Yeast Cell Wall and Cell Surface

Abstract: The structure and organization of the yeast cell wall and the nature of the cell surface have been investigated in terms of the composition of the wall; the structures of the wall components; the immunochemistry of the cell surface and binding of dyes, lectins, or specific antibodies; the degradative action of enzymes; and the visual evidence from scanning and thin-section electron microscopy. Most or all of these methods have been applied to the cells during vegetative growth, sporulation, and mating, and the analyses have been furthered by the availability in recent years of a variety of cell-wall mutants. A general conclusion from all of these studies is that yeast cell walls show less apparent organization than bacterial walls but that the yeast wall is as metabolically active and the cell surface as antigenically polymorphic as those of Gram-positive bacteria. To keep this review manageable, it will be limited in most instances to Saccharomyces cerevisiae , with only occasional reference to other yeasts. The aim is to treat the subject topics briefly and to direct the reader to several recent reviews in which leading references to the original literature can be found. VEGETATIVE CELL WALL Composition and Structure Three components, glucan, mannoprotein (previously called mannan), and chitin, make up over 90% of the cell wall, whereas only small and variable amounts of lipid have been reported (Phaff 1971). When grown on hexadecane, however, the cell wall of Candida tropicalis increases in covalently linked fatty acid (Kappeli et al. 1978). Thus, cell-wall composition...

Nucleotide sequence of the triose phosphate isomerase gene of Saccharomyces cerevisiae.

Abstract: The gene coding for the glycolytic enzyme triose phosphate isomerase (TPI1) was isolated from a yeast library in the shuttle vector pYE13. Selecting for a deletion mutant of the plasmid which enhances expression of the otherwise dormant yeast gene in E. coli facilitated the identification of the coding region. The DNA sequences of the wild type and mutant genes were determined by chemical methods. The 5' flanking region of the wild-type TPI1 resembles the analogous regions of the yeast genes coding for two other glycolytic enzymes. The sequence of the deletion mutant indicates that, upstream from -65 in the 5' flanking region, 3.3 kilobases have been lost from entirely within the yeast insert. The mutation reduces enzyme activity by tenfold in yeast, and its implications for the expression of the gene in yeast and E. coli are discussed. The amino acid sequence deduced from the nucleotide order is consistent with the electron density map of the protein as well as the sequence of its N-terminal 16 amino acids and amino acid composition. The amino acid sequence is approximately 50% homologous with the triose phosphate isomerases from rabbit, chicken, and coelacanth and 37% homologous with the Bacillus stearothermophilus enzyme. Residues which are thought to be catalytically important are conserved.

Yeast flora of grape berries during ripening

Abstract: The yeast flora associated with the surface of grapes during ripening was studied with regard to different sectors of the grape skin and the position in the bunch by means of traditional as well as more vigorous preisolation and precounting treatments. The yeast number per square centimeter of skin increases with ripening and is highest in the area immediately surrounding the stem. The cluster sector closer to the peduncle seems to constitute a favorable substrate for yeasts, hosting a resident flora about 10 and 100 times higher than the central and lower parts of the bunch, respectively.Kloeckera apiculata was the normal resident species of grapes regardless of the sector or the ripening period, and constitutes the fermenting flora of mature grapes. The ecological implications of the results of this survey are discussed.

Isolation of ethanol-tolerant mutants of yeast by continuous selection

Abstract: The ethanol tolerance of Saccharomyces species is an important constraint on the efficiency of the industrial production of ethanol by fermentation. The alcohol reduces the viability, growth rate and fermentation rate of the producing organism. The complexity of the effect make it difficult to isolate tolerant mutants by simple agar plate screening regimes. We have therefore turned to continuous selection in an attempt to isolate such mutants.

Nutritional studies in the seed production of fish-XII. Improvement of dietary value of brine shrimp Artemia salina for fish larvae by feeding them on .OMEGA.3 highly unsaturated fatty acids.

Abstract: Experiments were conducted in order to improve the dietary value for marine fish juveniles of Artemia naupii of the freshwater type, high in 18: 3ω3, by allowing them to feed directly on ω3 HUFA. In this method lipids containing ω3 HUFA were given directly to Artemia nauplii by homogenizing lipid with a small amount of raw egg yolk and water, together with baker's yeast; an emulsion resulted. The dietary value of the nauplii for juveniles of flunder, rock sea bream and red sea bream was compared for fish fed on various kinds of emulsified lipids or on baker's yeast. The newly-hatched nauplii were found to take up lipids very easily by this method. Feeding on the newly-hatched nauplii of the freshwater type or on those fed respectively baker's yeast and corn oil resulted in low growth and survival in all fish species used and in addition the rate of be effectively improved by feeding them lipids containing high amounts of ω3 HUFA such as cuttlefish liver oil, demonstrating that the class of EFA contained in Ariemia is the principal factor in the food value of Artemia nauplii to fish. Artemia eggs and nauplii from different locations (California, Brazil, Australia and China), were also analyzed for fatty acids in order to compare their food values to fish.

Activity and stability of glycolytic enzymes in the presence of ethanol

Abstract: An investigation of the effects of ethanol on both the stabilities and activities of glycolytic enzymes of yeast and Zymomonas mobilis is presented. It is concluded that enzyme denaturation is unlikely to play a direct part in ethanol tolerance, but inhibition by ethanol may be responsible for slowing some of the glycolytic reactions.

Glycerol Production of Various Strains of Saccharomyces

Abstract: The quantity of glycerol as principal by-product of the alcoholic fermentation depends to a large extent on the yeast strain. Different strains of Saccharomyces cerevisiae were found to form amounts of glycerol varying between 4.2 to 10.4 g/L. The formation of glycerol is regarded as a result of the competition between alcohol dehydrogenase and glycerol-3-phosphate dehydrogenase that compete for the reduced coenzyme NADH2. High and low glycerol forming yeast strains showed large differences in the activity of glycerol-3-phosphate dehydrogenase and only small variations in the activity of alcohol dehydrogenase. The total amount of glycerol formed was also influenced by amino acids. In thiamine deficient media a decrease in glycerol formation was observed. Experiments indicate a correlation between the formation of acetaldehyde and glycerol and the production of cell mass that may be of practical interest. Glycerol is by far the most important secondary product of fermentation. The glycerol content of wine may be of two different origins. A certain amount of glycerol is always formed by yeasts. Occasionally, glycerol is already present in the grape must, as has been observed by Mtihlberger and Grohmann (7). This glycerol is formed by Boyrytis cinerea, a fungus which frequently attacks grapes when they are produced in humid climates. The amount of glycerol formed by yeasts is generally assumed to be in the range of 1/10 or 1/15 of the alcohol formed (11). The formation of glycerol is not constant but depends on various factors. Early observations date back to the last century. Because of the sweet taste that is similar to glucose (11), a high content of glycerol may have a favorable effect on the taste of wines. Besides the yeast strain, such factors as oxygen, fermentation temperatures, and pH have been reported to influence the formation of glycerol. Within the "normal" range of conditions these factors are obviously not very important, particularly when the range of the pH is kept between 2.8 to 5.0. There is no doubt that the formation of glycerol does not only depend on the yeast strain, but also to a large extent on the composition of the fermentation medium. It is the purpose of this paper to show how environmental factors and characters of yeast strains influence the formation of glycerol during fermentation.