Science.gov

Sample records for yeast phaffia rhodozyma

  1. Production of astaxanthin from cellulosic biomass sugars by mutants of the yeast Phaffia rhodozyma

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Astaxanthin is a carotenoid of high value to the aquaculture, nutraceutical, and pharmaceutical industries. Three mutant strains of the astaxanthin-producing yeast Phaffia rhodozyma, which were derived from the parent strain ATCC 24202 (UCD 67-210) and designated JTM166, JTM185, and SSM19, were test...

  2. Effect of dietary astaxanthin rich yeast, Phaffia rhodozyma, on meat quality of broiler chickens.

    PubMed

    Perenlei, Ganzaya; Tojo, Hitomi; Okada, Toru; Kubota, Masatoshi; Kadowaki, Motoni; Fujimura, Shinobu

    2014-10-01

    We evaluated effects of dietary supplementation with astaxanthin (Ax)-rich yeast, Phaffia rhodozyma (Xanthophyllomyces dendrorhous), on broiler chicken meat quality. Fourteen-day-old female Ross broilers were divided into three groups: control group, Ax-free diet; Ax 10 group, 10 mg/kg Ax diet; and Ax 20 group, 20 mg/kg Ax diet for 28 days. At 42 days old, chickens were slaughtered, and then growth performance, meat quality and sensory attributes were analyzed. Compared with the control, a* values increased significantly after slaughter and 48 h postmortem for Ax 20 samples (P<0.05) and for b* values in Ax 20 and Ax 10 groups (P<0.05). Cooking loss decreased in the Ax 20 group (P<0.05). After 120 h aging, contents of several free amino acids and total free amino acid content of Ax 20 group were significantly higher than the control (P<0.05). In sensory evaluation, meat texture attributes improved significantly in the Ax 20 group (P<0.01). No significant changes occurred in flavor attribute scores of meat soup from the Ax 20 group compared with the control even though most assessors preferred meat soup from the Ax 20 group. Overall, Ax-rich yeast in the diet improves broiler chicken meat quality.

  3. Impact of gamma rays on the Phaffia rhodozyma genome revealed by RAPD-PCR

    PubMed Central

    Najafi, N; Hosseini, Ramin; Ahmadi, AR

    2011-01-01

    Background and Objectives Phaffia rhodozyma is a red yeast which produces astaxanthin as the major carotenoid pigment. Astaxanthin is thought to reduce the incidence of cancer and degenerative diseases in man. It also enhances the immune response and acts as a free-radical quencher, a precursor of vitamin A, or a pigment involved in the visual attraction of animals as mating partners. The impact of gamma irradiation was studied on the Phaffia rhodozyma genome. Materials and Methods Ten mutant strains, designated Gam1-Gam10, were obtained using gamma irradiation. Ten decamer random amplified polymorphic DNA (RAPD) primers were employed to assess genetic changes. Results Nine primers revealed scorable polymorphisms and a total of 95 band positions were scored; amongst which 38 bands (37.5%) were polymorphic. Primer F with 3 bands and primer J20 with 13 bands produced the lowest and the highest number of bands, respectively. Primer A16 produced the highest number of polymorphic bands (70% polymorphism) and primer F showed the lowest number of polymorphic bands (0% polymorphism). Genetic distances were calculated using Jaccard's coefficient and the UPGMA method. A dendrogram was created using SPSS (version 11.5) and the strains were clustered into four groups. Conclusion RAPD markers could distinguish between the parental and the mutant strains of P. rhodozyma. RAPD technique showed that some changes had occurred in the genome of the mutated strains. This technique demonstrated the capability to differentiate between the parental and the mutant strains. PMID:22530091

  4. 21 CFR 73.355 - Phaffia yeast.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.355 Phaffia yeast. (a) Identity. (1) The color additive... stabilized color additive mixture. Color additive mixtures for fish feed use made with phaffia yeast may... additive mixtures for coloring foods. (b) Specifications. Phaffia yeast shall conform to the...

  5. 21 CFR 73.355 - Phaffia yeast.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Phaffia yeast. 73.355 Section 73.355 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.355 Phaffia yeast. (a) Identity. (1) The color additive phaffia yeast consists of the killed, dried cells of a nonpathogenic and nontoxicogenic strain of...

  6. 21 CFR 73.355 - Phaffia yeast.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Phaffia yeast. 73.355 Section 73.355 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.355 Phaffia yeast. (a) Identity. (1) The color additive phaffia yeast consists of the killed, dried cells of a nonpathogenic and nontoxicogenic strain of...

  7. 21 CFR 73.355 - Phaffia yeast.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Phaffia yeast. 73.355 Section 73.355 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.355 Phaffia yeast. (a) Identity. (1) The color additive phaffia yeast consists of the killed, dried cells of a nonpathogenic and nontoxicogenic strain of...

  8. 21 CFR 73.355 - Phaffia yeast.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Phaffia yeast. 73.355 Section 73.355 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.355 Phaffia yeast. (a) Identity. (1) The color additive phaffia yeast consists of the killed, dried cells of a nonpathogenic and nontoxicogenic strain of...

  9. Production of carotenoids by phaffia rhodozyma growing on media made from hemicellulosic hydrolysates of eucalyptus globulus wood

    PubMed

    Parajo; Santos; Vazquez

    1998-08-20

    Phaffia rhodozyma NRRL Y-17268 cells were proliferated in xylose-containing media made from Eucalyptus wood. Wood samples were subjected to acid hydrolysis under mild operational conditions, and hydrolysates were neutralized with lime. Neutralized hydrolysates were treated with charcoal for removing inhibitors and then supplemented with nutrients to obtain culture media useful for proliferation of the red yeast P. rhodozyma. A set of experiments carried out in orbital shakers proved that hydrolysates containing 16.6 g xylose/L supplemented only with 3 g peptone/L performed well as fermentation media. At the end of experiments, xylose was depleted and 10.5 g cells/L were obtained. Biomass was highly pigmented and volumetric carotenoid concentrations up to 5.8 mg carotenoids/L (with 4.6 mg astaxanthin/L) were reached. Further experiments in batch fermentors using concentrated hydrolysates (initial xylose concentrations within 16.6 and 40.8 g/L) led to good biomass concentrations (up to 23.2 g cells/L) with increased pigment concentration (up to 12.9 mg total carotenoids/L, with 10.4 mg astaxanthin/L) and high volumetric rates of carotenoid production (up to 0.079 mg/L.h). Copyright 1998 John Wiley & Sons, Inc.

  10. Separation of astaxanthin from cells of Phaffia rhodozyma using colloidal gas aphrons in a flotation column.

    PubMed

    Dermiki, Maria; Bourquin, Anne Lise; Jauregi, Paula

    2010-01-01

    The aim of this study is to investigate the separation of astaxanthin from the cells of Phaffia rhodozyma using colloidal gas aphrons (CGA), which are surfactant stabilized microbubbles, in a flotation column. It was reported in previous studies that optimum recoveries are achieved at conditions that favor electrostatic interactions. Therefore, in this study, CGA generated from the cationic surfactant hexadecyl trimethyl ammonium bromide (CTAB) were applied to suspensions of cells pretreated with NaOH. The different operation modes (batch or continuous) and the effect of volumetric ratio of CGA to feed, initial concentration of feed, operating height, and flow rate of CGA on the separation of astaxanthin were investigated. The volumetric ratio was found to have a significant effect on the separation of astaxanthin for both batch and continuous experiments. Additionally, the effect of homogenization of the cells on the purity of the recovered fractions was investigated, showing that the homogenization resulted in increased purity. Moreover, different concentrations of surfactant were used for the generation of CGA for the recovery of astaxanthin on batch mode; it was found that recoveries up to 98% could be achieved using CGA generated from a CTAB solution 0.8 mM, which is below the CTAB critical micellar concentration (CMC). These results offer important information for the scale-up of the separation of astaxanthin from the cells of P. rhodozyma using CGA.

  11. [Repeated batch and fed-batch process for astaxanthin production by Phaffia rhodozyma].

    PubMed

    Xiao, Anfeng; Ni, Hui; Li, Lijun; Cai, Huinong

    2011-04-01

    A comparative study of batch and repeated batch process was carried out for astaxanthin fermentation of Phaffia rhodozyma to develop a more economical method for astaxanthin industrial production. In shaking flask fermentation, the change of biomass and astaxanthin production was studied to compare the five-day cycle with four-day cycle of repeated batch culture of P. rhodozyma. Astaxanthin production increased at first and then decreased subsequently in seven cycles, yet the yield of astaxanthin in the next six cycles remains higher than that of the first cycle. Comparing the average production of astaxanthin in the seven cycles, four-day cycle performed even better than five-day cycle. Subsequently, a repeated fed-batch process was used in a 5-1 bioreactor. The experimental data showed that biomass and astaxanthin production of the second batch could reach the level of the first batch, no matter that the carbon source was glucose or hydrolysis sugar of starch. This result showed that this strain had good stability, and thus repeated batch and fed-batch process could be applied in astaxanthin fermentation for economical purpose.

  12. Separation and purification of astaxanthin from Phaffia rhodozyma by preparative high-speed counter-current chromatography.

    PubMed

    Du, Xiping; Dong, Congcong; Wang, Kai; Jiang, Zedong; Chen, Yanhong; Yang, Yuanfan; Chen, Feng; Ni, Hui

    2016-09-01

    An effective high-speed counter-current chromatography (HSCCC) method was established for the preparative isolation and purification of astaxanthin from Phaffia rhodozyma. With a two-phase solvent system composed of n-hexane-acetone-ethanol-water (1:1:1:1, v/v/v/v), 100mg crude extract of P. rhodozyma was separated to yield 20.6mg of astaxanthin at 92.0% purity. By further one step silica gel column chromatography, the purity reached 99.0%. The chemical structure of astaxanthin was confirmed by thin layer chromatography (TLC), UV spectroscopy scanning, high performance liquid chromatography with a ZORBAX SB-C18 column and a Waters Nova-pak C18 column, and ESI/MS/MS.

  13. The effect of gamma irradiation on astaxanthin synthetase encoding gene in two mutant strains of Phaffia rhodozyma

    PubMed Central

    Najafi, Naeimeh; Hosseini, Ramin; Ahmadi, Ali-Reza

    2013-01-01

    Background and Objectives Astaxanthin, an orange-red carotenoid pigment, acts as a protective agent against oxidative damage to cells in vivo. The astaxanthin synthetase gene (crtS) size consists of 3995 bp. This gene has been suggested to catalyse β-carotene to astaxanthin in Phaffia rhodozyma. The aim of this research was to find any possible changes in this gene in two mutant strains, Gam1 and Gam2 (with high astaxanthin pigment production), previously created by gamma irradiation. Materials and Methods The astaxanthin synthetase gene sequence of Phaffia rhodozyma in the NCBI Gene bank was used to design primer. In Gam1, this gene was amplified using primers Asta F1, Asta R2, Asta F3, Asta R4. In Gam2, primers asta F1, asta R4 were used to amplify the gene. The amplified fragments were 8 sequenced using primers Asta F1, Asta R1, Asta F2, Asta R2, Asta F3, Asta R3 and Asta F4, Asta R4. Astaxanthin synthetase gene from two mutant strains, Gam1 and Gam2 were amplified using PCR. The amplified products were sequenced and aligned using the ClustalW software. Conclusion The comparison of this gene showed 98% and 99% similarities between the reference sequence and Gam1 and Gam2 mutant strains, respectively, whereas the comparison of this gene in Gam1 and Gam2 mutant strains showed 97% similarity. However, the deduced proteins showed 78% and 83% between the reference protein obtained from the wild type and Gam1 and Gam2, respectively. This similarity was 75% between the mutant strains. PMID:24475339

  14. Bioconversions of maize residues to value-added coproducts using yeast-like fungi.

    PubMed

    Leathers, Timothy D

    2003-04-01

    Agricultural residues are abundant potential feedstocks for bioconversions to industrial fuels and chemicals. Every bushel of maize (approximately 25 kg) processed for sweeteners, oil, or ethanol generates nearly 7 kg of protein- and fiber-rich residues. Currently these materials are sold for very low returns as animal feed ingredients. Yeast-like fungi are promising biocatalysts for conversions of agricultural residues. Although corn fiber (pericarp) arabinoxylan is resistant to digestion by commercially available enzymes, a crude mixture of enzymes from the yeast-like fungus Aureobasidium partially saccharifies corn fiber without chemical pretreatment. Sugars derived from corn fiber can be converted to ethanol or other valuable products using a variety of naturally occurring or recombinant yeasts. Examples are presented of Pichia guilliermondii strains for the conversion of corn fiber hydrolysates to the alternative sweetener xylitol. Corn-based fuel ethanol production also generates enormous volumes of low-value stillage residues. These nutritionally rich materials are prospective substrates for numerous yeast fermentations. Strains of Aureobasidium and the red yeast Phaffia rhodozyma utilize stillage residues for production of the polysaccharide pullulan and the carotenoid astaxanthin, respectively.

  15. Red yeasts and carotenoid production: outlining a future for non-conventional yeasts of biotechnological interest.

    PubMed

    Mannazzu, Ilaria; Landolfo, Sara; Lopes da Silva, Teresa; Buzzini, Pietro

    2015-11-01

    Carotenoids are one of the most common classes of pigments that occur in nature. Due to their biological properties, they are widely used in phytomedicine and in the chemical, pharmaceutical, cosmetic, food and feed industries. Accordingly, their global market is continuously growing, and it is expected to reach about US$1.4 billion in 2018. Carotenoids can be easily produced by chemical synthesis, although their biotechnological production is rapidly becoming an appealing alternative to the chemical route, partly due to consumer concerns against synthetic pigments. Among the yeasts, and apart from the pigmented species Phaffia rhodozyma (and its teleomorph Xanthophyllomyces dendrorhous), a handful of species of the genera Rhodosporidium, Rhodotorula, Sporobolomyces and Sporidiobolus are well known carotenoid producers. These are known as 'red yeasts', and their ability to synthesize mixtures of carotenoids from low-cost carbon sources has been broadly studied recently. Here, in agreement with the renewed interest in microbial carotenoids, the recent literature is reviewed regarding the taxonomy of the genera Rhodosporidium, Rhodotorula, Sporobolomyces and Sporidiobolus, the stress factors that influence their carotenogenesis, and the most advanced analytical tools for evaluation of carotenoid production. Moreover, a synopsis of the molecular and "-omic" tools available for elucidation of the metabolic pathways of the microbial carotenoids is reported.

  16. Studies of astaxanthin biosynthesis in Xanthophyllomyces dendrorhous (Phaffia rhodozyma). Effect of inhibitors and low temperature.

    PubMed

    Ducrey Sanpietro, L M; Kula, M R

    1998-08-01

    The effect of nicotine and diphenylamine on astaxanthin biosynthesis in Xanthophyllomyces dendrorhous was studied. The effects were analysed under standard and low temperature conditions. It was found that 10 mM-nicotine inhibits the cyclization of lycopene and de novo protein synthesis was not needed to reverse the inhibition. The oxidation of beta-carotene was irreversibly inhibited by 10 microM-diphenylamine while the dehydrogenation of phytoene was reversibly inhibited by 60 microM-diphenylamine. The simultaneous exposure to low temperature (4 degrees C) overcomes the inhibition of beta-carotene oxidation at low diphenylamine concentration.

  17. Effect of supplementation of University of Wisconsin solution with glycoproteins from psychrophilic strains of yeast on hypothermic liver storage of rats.

    PubMed

    Tilser, I; Breierová, E; Tichý, M; Skalská, H; Ettlerová, E

    1996-06-01

    Extracellular yeast glycoproteins (YG) produced by Rhodosporidium toruloides have been shown to increase the survival rate of different yeast species after storage in liquid nitrogen. The purpose of this study was to investigate the effect of YG on cold-stored rat livers. Water-soluble YG produced either by Phaffia rhodozyma (G3) or by Leucosporidium antarcticum (G4) were added to a modified University of Wisconsin solution (mUW) and used for cold storage (1 degree C) of isolated livers. The functional status of each liver was then assessed under conditions of 90-min normothermic reperfusion. The 46-h cold storage in mUW without G3 and G4 resulted in serious preservation-reperfusion injury of the liver. The addition of G3 to mUW for 46-h preservation of the liver resulted in significantly higher bile flow (4.32 +/- 0.35 vs 2.35 +/- 0.49 microliters/min/10 g at 75-90 min), higher portal blood flow (10.99 +/- 0.2 vs 4.78 +/- 1.07 ml/min/g at 90 min), lower liver weight after reperfusion (102.4 +/- 1.5 vs 116.7 +/- 6.6% of weight before preservation), and lower total tissue water after reperfusion (2.49 +/- 0.05 vs 2.92 +/- 0.13 g water/g dry weight). However, the activity of ALT, AST, and LDH in perfusate was not changed. The beneficial effect of G4 was less pronounced. The 24-h storage in mUW resulted in a significant increase of AST and LDH activity in perfusate; the addition of G3 to mUW for 24-h preservation did not affect these parameters. In conclusion, the addition of 0.05% G3 or G4 to mUW was only partially beneficial in improving rat liver preservation.

  18. An unusual Xanthophyllomyces strain from leaves of Eucalyptus globulus in Chile.

    PubMed

    Weber, Roland W S; Becerra, José; Silva, Mario J; Davoli, Paolo

    2008-07-01

    Xanthophyllomyces sp. was isolated as an epiphytic red yeast from leaves of Eucalyptus glo-bulus in Concepción, Chile. Sexual reproduction was by basidiospores produced from one or rarely two metabasidia arising from a yeast cell without preceding paedogamy. The main carotenoid pigment was astaxanthin. This isolate did not cluster with the X. dendrorhous complex (including Phaffia rhodozyma) in ITS and 26S rDNA-based phylogenetic analyses. The phylloplane may be a further habitat for Xanthophyllomyces, in addition to the well-known spring sap-flows of deciduous trees and the recently-characterised ascostromata of Cyttaria hariotii.

  19. Genetic Dissection of Sexual Reproduction in a Primary Homothallic Basidiomycete

    PubMed Central

    Sampaio, José Paulo; Gonçalves, Paula

    2016-01-01

    In fungi belonging to the phylum Basidiomycota, sexual compatibility is usually determined by two genetically unlinked MAT loci, one of which encodes one or more pheromone receptors (P/R) and pheromone precursors, and the other comprehends at least one pair of divergently transcribed genes encoding homeodomain (HD) transcription factors. Most species are heterothallic, meaning that sexual reproduction requires mating between two sexually compatible individuals harboring different alleles at both MAT loci. However, some species are known to be homothallic, one individual being capable of completing the sexual cycle without mating with a genetically distinct partner. While the molecular underpinnings of the heterothallic life cycles of several basidiomycete model species have been dissected in great detail, much less is known concerning the molecular basis for homothallism. Following the discovery in available draft genomes of the homothallic basidiomycetous yeast Phaffia rhodozyma of P/R and HD genes, we employed available genetic tools to determine their role in sexual development. Two P/R clusters, each harboring one pheromone receptor and one pheromone precursor gene were found in close vicinity of each other and were shown to form two redundant P/R pairs, each receptor being activated by the pheromone encoded by the most distal pheromone precursor gene. The HD locus is apparently genetically unlinked to the P/R locus and encodes a single pair of divergently transcribed HD1 and HD2 transcription factors, both required for normal completion of the sexual cycle. Given the genetic makeup of P. rhodozyma MAT loci, we postulate that it is a primarily homothallic organism and we propose a model for the interplay of molecular interactions required for sexual development in this species. Phaffia rhodozyma is considered one of the most promising microbial source of the carotenoid astaxanthin. Further development of this yeast as an industrial organism will benefit from

  20. Counting Yeast.

    ERIC Educational Resources Information Center

    Bealer, Jonathan; Welton, Briana

    1998-01-01

    Describes changes to a traditional study of population in yeast colonies. Changes to the procedures include: (1) only one culture per student team; (2) cultures are inoculated only once; and (3) the same tube is sampled daily. (DDR)

  1. Vaginal Yeast Infections

    MedlinePlus

    ... Surgery? A Week of Healthy Breakfasts Shyness Vaginal Yeast Infections KidsHealth > For Teens > Vaginal Yeast Infections Print ... side effect of taking antibiotics. What Is a Yeast Infection? A yeast infection is a common infection ...

  2. Production, extraction, and quantification of astaxanthin by Xanthophyllomyces dendrorhous or Haematococcus pluvialis: standardized techniques.

    PubMed

    Domínguez-Bocanegra, Alma Rosa

    2012-01-01

    For many years, benefits and disadvantages of pigments production either by microalgae or yeasts have been under analysis. In this contribution we shall deal with Xanthophyllomyces dendrorhous (formerly Phaffia rhodozyma) and Haematococcus pluvialis, which are known as major prominent microorganisms able to synthesize astaxanthin pigment. Then, the usual trend is to look for optimal conditions to conduct astaxanthin synthesis. From one side, pigment production by H. pluvialis is promoted under cellular stress conditions like nutrient deprivation, exposition to high light intensity, aeration. On the other side, X. dendrorhous is able to show significant increase in astaxanthin synthesis when grown in natural carbon sources like coconut milk, grape juice. The main aim of this chapter is to describe optimal environmental conditions for astaxanthin production by X. dendrorhous or H. pluvialis.

  3. Yeast extracellular proteases.

    PubMed

    Ogrydziak, D M

    1993-01-01

    Many species of yeast secrete significant amounts of protease(s). In this article, results of numerous surveys of yeast extracellular protease production have been compiled and inconsistencies in the data and limitations of the methodology have been examined. Regulation, purification, characterization, and processing of yeast extracellular proteases are reviewed. Results obtained from the sequences of cloned genes, especially the Saccharomyces cerevisiae Bar protease, the Candida albicans acid protease, and the Yarrowia lipolytica alkaline protease, have been emphasized. Biotechnological applications and the medical relevance of yeast extracellular proteases are covered. Yeast extracellular proteases have potential in beer and wine stabilization, and they probably contribute to pathogenicity of Candida spp. Yeast extracellular protease genes also provide secretion and processing signals for yeast expression systems designed for secretion of heterologous proteins. Coverage of the secretion of foreign proteases such as prochymosin, urokinase, and tissue plasminogen activator by yeast in included.

  4. Protein expression-yeast.

    PubMed

    Nielsen, Klaus H

    2014-01-01

    Yeast is an excellent system for the expression of recombinant eukaryotic proteins. Both endogenous and heterologous proteins can be overexpressed in yeast (Phan et al., 2001; Ton and Rao, 2004). Because yeast is easy to manipulate genetically, a strain can be optimized for the expression of a specific protein. Many eukaryotic proteins contain posttranslational modifications that can be performed in yeast but not in bacterial expression systems. In comparison with mammalian cell culture expression systems, growing yeast is both faster and less expensive, and large-scale cultures can be performed using fermentation. While several different yeast expression systems exist, this chapter focuses on the budding yeast Saccharomyces cerevisiae and will briefly describe some options to consider when selecting vectors and tags to be used for protein expression. Throughout this chapter, the expression and purification of yeast eIF3 is shown as an example alongside a general scheme outline.

  5. Yeast Based Sensors

    NASA Astrophysics Data System (ADS)

    Shimomura-Shimizu, Mifumi; Karube, Isao

    Since the first microbial cell sensor was studied by Karube et al. in 1977, many types of yeast based sensors have been developed as analytical tools. Yeasts are known as facultative anaerobes. Facultative anaerobes can survive in both aerobic and anaerobic conditions. The yeast based sensor consisted of a DO electrode and an immobilized omnivorous yeast. In yeast based sensor development, many kinds of yeast have been employed by applying their characteristics to adapt to the analyte. For example, Trichosporon cutaneum was used to estimate organic pollution in industrial wastewater. Yeast based sensors are suitable for online control of biochemical processes and for environmental monitoring. In this review, principles and applications of yeast based sensors are summarized.

  6. Vaginal yeast infection

    MedlinePlus

    Yeast infection - vagina; Vaginal candidiasis; Monilial vaginitis ... Most women have a vaginal yeast infection at some time. Candida albicans is a common type of fungus. It is often found in small amounts in the ...

  7. Yeast Infection during Pregnancy

    MedlinePlus

    ... OK? What's the best way to treat a yeast infection during pregnancy? Answers from Yvonne Butler Tobah, M.D. You can safely treat a yeast infection during pregnancy with various over-the-counter ...

  8. Yeast DNA plasmids.

    PubMed

    Gunge, N

    1983-01-01

    The study of yeast DNA plasmids has been initiated with the discovery of the 2-micron DNA in Saccharomyces cerevisiae. This multiple copy plasmid, organized into chromatin structure in vivo, probably exists in the nucleus and provides a good system to obtain information on eukaryotic DNA replication. Yeast transformation with the 2-micron DNA or artificially constructed chimeric plasmids had contributed significantly to the study of the molecular biology of yeast and eukaryotes, allowing the isolation and characterization of various genes, ars, centromeres, and telomeres, and also serving as a tool to study the expression of various heterologous genes. Encouraged by these fruitful results, new yeast plasmids have been screened among phylogenetically distant yeasts. The linear DNA plasmids (pGKl1 and pGKl2) from Kluyveromyces lactis are the first case of yeast plasmids associated with biological function (killer phenotype). This plasmid system would be ideal as a model to study the structure and function of eukaryotic linear chromosomes. The extracellular secretion of protein toxin suggests the plasmids to be an excellent candidate for a secretion vector. The importance of yeasts as suitable materials for the study of eukaryotic cell biology would be much enhanced by the advent of new transformation systems with diverse host yeasts of genetically and phylogenetically distinct properties.

  9. The yeast Golgi apparatus.

    PubMed

    Suda, Yasuyuki; Nakano, Akihiko

    2012-04-01

    The Golgi apparatus is an organelle that has been extensively studied in the model eukaryote, yeast. Its morphology varies among yeast species; the Golgi exists as a system of dispersed cisternae in the case of the budding yeast Saccharomyces cerevisiae, whereas the Golgi cisternae in Pichia pastoris and Schizosaccharomyces pombe are organized into stacks. In spite of the different organization, the mechanism of trafficking through the Golgi apparatus is believed to be similar, involving cisternal maturation, in which the resident Golgi proteins are transported backwards while secretory cargo proteins can stay in the cisternae. Questions remain regarding the organization of the yeast Golgi, the regulatory mechanisms that underlie cisternal maturation of the Golgi and transport machinery of cargo proteins through this organelle. Studies using different yeast species have provided hints to these mechanisms.

  10. Yeast Proteome Analysis

    NASA Astrophysics Data System (ADS)

    Matros, Andrea; Mock, Hans-Peter

    Yeast organisms, and specifically Saccharomyces cerevisiae, have become model systems for many aspects in fundamental and applied research. Consistently, many papers have been published applying proteome techniques to study these organisms. The review will give an overview on the proteome research performed on yeast systems so far; however, due to the large number of publications, only selected reports can be cited neglecting many more interesting ones in the interest of space. The review will focus on research involving mass spectrom-etry as a basic proteome technique, although many more approaches are relevant for the functional characterization of proteins in the cell, e.g. the yeast two-hybrid system. We will provide an overview on yeasts as models in the context of pro-teome analysis, and explain the basic techniques currently applied in proteome approaches. The main part of the review will deal with a survey on the current status of proteomic studies in yeasts. In a first part of this chapter, we will deal with the currently available proteome maps of yeasts, and in the following part we will discuss studies dealing with fundamental aspects, but also mention proteome studies related to applied microbiology. Finally, we will envisage future perspectives of the proteome technology for studying yeasts, and draw major conclusion on the current status reached in this field of functional genomics.

  11. Yeast (Saccharomyces cerevisiae).

    PubMed

    Hooykaas, Paul J J; den Dulk-Ras, Amke; Bundock, Paul; Soltani, Jalal; van Attikum, Haico; van Heusden, G Paul H

    2006-01-01

    The yeast Saccharomyces cerevisiae is one of the best characterized eukaryotic organisms. This species has enabled a detailed study of the (genetic) requirements for Agrobacterium-mediated DNA transformation. For instance research with this yeast has led to the recognition that the transforming DNA molecules integrate into the eukaryotic chromosomes either by homologous recombination, which is the preferred pathway in S. cerevisiae, or by nonhomologous end-joining. Based on the protocol for Agrobacterium-mediated transformation of S. cerevisiae methodology has been developed for the transformation of many other yeast and fungal species.

  12. Replicative Aging in Yeast

    PubMed Central

    Steinkraus, K.A.; Kaeberlein, M.; Kennedy, B.K.

    2009-01-01

    Progress in aging research is now rapid, and surprisingly, studies in a single-celled eukaryote are a driving force. The genetic modulators of replicative life span in yeast are being identified, the molecular events that accompany aging are being discovered, and the extent to which longevity pathways are conserved between yeast and multicellular eukaryotes is being tested. In this review, we provide a brief retrospective view on the development of yeast as a model for aging and then turn to recent discoveries that have pushed aging research into novel directions and also linked aging in yeast to well-developed hypotheses in mammals. Although the question of what causes aging still cannot be answered definitively, that day may be rapidly approaching. PMID:18616424

  13. Nitrile Metabolizing Yeasts

    NASA Astrophysics Data System (ADS)

    Bhalla, Tek Chand; Sharma, Monica; Sharma, Nitya Nand

    Nitriles and amides are widely distributed in the biotic and abiotic components of our ecosystem. Nitrile form an important group of organic compounds which find their applications in the synthesis of a large number of compounds used as/in pharmaceutical, cosmetics, plastics, dyes, etc>. Nitriles are mainly hydro-lyzed to corresponding amide/acid in organic chemistry. Industrial and agricultural activities have also lead to release of nitriles and amides into the environment and some of them pose threat to human health. Biocatalysis and biotransformations are increasingly replacing chemical routes of synthesis in organic chemistry as a part of ‘green chemistry’. Nitrile metabolizing organisms or enzymes thus has assumed greater significance in all these years to convert nitriles to amides/ acids. The nitrile metabolizing enzymes are widely present in bacteria, fungi and yeasts. Yeasts metabolize nitriles through nitrilase and/or nitrile hydratase and amidase enzymes. Only few yeasts have been reported to possess aldoxime dehydratase. More than sixty nitrile metabolizing yeast strains have been hither to isolated from cyanide treatment bioreactor, fermented foods and soil. Most of the yeasts contain nitrile hydratase-amidase system for metabolizing nitriles. Transformations of nitriles to amides/acids have been carried out with free and immobilized yeast cells. The nitrilases of Torulopsis candida>and Exophiala oligosperma>R1 are enantioselec-tive and regiospecific respectively. Geotrichum>sp. JR1 grows in the presence of 2M acetonitrile and may have potential for application in bioremediation of nitrile contaminated soil/water. The nitrilase of E. oligosperma>R1 being active at low pH (3-6) has shown promise for the hydroxy acids. Immobilized yeast cells hydrolyze some additional nitriles in comparison to free cells. It is expected that more focus in future will be on purification, characterization, cloning, expression and immobilization of nitrile metabolizing

  14. Forces in yeast flocculation

    NASA Astrophysics Data System (ADS)

    El-Kirat-Chatel, Sofiane; Beaussart, Audrey; Vincent, Stéphane P.; Abellán Flos, Marta; Hols, Pascal; Lipke, Peter N.; Dufrêne, Yves F.

    2015-01-01

    In the baker's yeast Saccharomyces cerevisiae, cell-cell adhesion (``flocculation'') is conferred by a family of lectin-like proteins known as the flocculin (Flo) proteins. Knowledge of the adhesive and mechanical properties of flocculins is important for understanding the mechanisms of yeast adhesion, and may help controlling yeast behaviour in biotechnology. We use single-molecule and single-cell atomic force microscopy (AFM) to explore the nanoscale forces engaged in yeast flocculation, focusing on the role of Flo1 as a prototype of flocculins. Using AFM tips labelled with mannose, we detect single flocculins on Flo1-expressing cells, showing they are widely exposed on the cell surface. When subjected to force, individual Flo1 proteins display two distinct force responses, i.e. weak lectin binding forces and strong unfolding forces reflecting the force-induced extension of hydrophobic tandem repeats. We demonstrate that cell-cell adhesion bonds also involve multiple weak lectin interactions together with strong unfolding forces, both associated with Flo1 molecules. Single-molecule and single-cell data correlate with microscale cell adhesion behaviour, suggesting strongly that Flo1 mechanics is critical for yeast flocculation. These results favour a model in which not only weak lectin-sugar interactions are involved in yeast flocculation but also strong hydrophobic interactions resulting from protein unfolding.

  15. Enzymatic fractionation of SAA-pretreated barley straw for production of fuel ethanol and astaxanthin as a value-added co-product.

    PubMed

    Nghiem, Nhuan P; Kim, Tae Hyun; Yoo, Chang Geun; Hicks, Kevin B

    2013-09-01

    Barley straw was used to demonstrate an integrated process for production of fuel ethanol and astaxanthin as a value-added co-product. Barley straw was pretreated by soaking in aqueous ammonia using the previously determined optimum conditions, which included 77.6 °C treatment temperature, 12.1 h treatment time, 15 wt% ammonia concentration, and 1:8 solid-to-liquid ratio. In the newly developed process, the pretreated barley straw was first hydrolyzed with ACCELLERASE® XY (a commercial hemicellulase product) to generate a xylose-rich solution, which contained 3.8 g/l glucose, 22.9 g/l xylose, and 2.4 g/l arabinose, with 96 % of the original glucan being left intact. The xylose-rich solution was used for production of astaxanthin by the yeast Phaffia rhodozyma without further treatment. The resulting cellulose-enriched solid residue was used for ethanol production in a fed-batch simultaneous saccharification and fermentation using ACCELLERASE® 1500 (a commercial cellulase product) and the industrial yeast Saccharomyces cerevisiae. At the end of the fermentation, 70 g/l ethanol was obtained, which was equivalent to 63 % theoretical yield based on the glucan content of the solid substrate.

  16. Cassava starch maltodextrinization/monomerization through thermopressurized aqueous phosphoric acid hydrolysis.

    PubMed

    Fontana, J D; Passos, M; Baron, M; Mendes, S V; Ramos, L P

    2001-01-01

    Kinetic conditions were established for the depolymerization of cassava starch for the production of maltodextrins and glucose syrups. Thin-layer chromatography and high-performance liquid chromatography analyses corroborated that the proper H3PO4 strength and thermopressurization range (e.g., 142-170 degrees C; 2.8-6.8 atm) can be successfully explored for such hydrolytic purposes of native starch granules. Because phosphoric acid can be advantageously maintained in the hydrolysate and generates, after controlled neutralization with ammonia, the strategic nutrient triplet for industrial fermentations (C, P, N), this pretreatment strategy can be easily recognized as a recommended technology for hydrolysis and upgrading of starch and other plant polysaccharides. Compared to the classic catalysts, the mandatory desalting step (chloride removal by expensive anion-exchange resin or sulfate precipitation as the calcium-insoluble salt) can be avoided. Furthermore, properly diluted phosphoric acid is well known as an allowable additive in several popular soft drinks such as colas since its acidic feeling in the mouth is compatible and synergistic with both natural and artificial sweeteners. Glycosyrups from phosphorolyzed cassava starch have also been upgraded to high-value single-cell protein such as the pigmented yeast biomass of Xanthophyllomyces dendrorhous (Phaffia rhodozyma), whose astaxanthin (diketo-dihydroxy-beta-carotene) content may reach 0.5-1.0 mg/g of dry yeast cell. This can be used as an ideal complement for animal feeding as well as a natural staining for both fish farming (meat) and poultry (eggs).

  17. Mapping yeast transcriptional networks.

    PubMed

    Hughes, Timothy R; de Boer, Carl G

    2013-09-01

    The term "transcriptional network" refers to the mechanism(s) that underlies coordinated expression of genes, typically involving transcription factors (TFs) binding to the promoters of multiple genes, and individual genes controlled by multiple TFs. A multitude of studies in the last two decades have aimed to map and characterize transcriptional networks in the yeast Saccharomyces cerevisiae. We review the methodologies and accomplishments of these studies, as well as challenges we now face. For most yeast TFs, data have been collected on their sequence preferences, in vivo promoter occupancy, and gene expression profiles in deletion mutants. These systematic studies have led to the identification of new regulators of numerous cellular functions and shed light on the overall organization of yeast gene regulation. However, many yeast TFs appear to be inactive under standard laboratory growth conditions, and many of the available data were collected using techniques that have since been improved. Perhaps as a consequence, comprehensive and accurate mapping among TF sequence preferences, promoter binding, and gene expression remains an open challenge. We propose that the time is ripe for renewed systematic efforts toward a complete mapping of yeast transcriptional regulatory mechanisms.

  18. Yeasts associated with Manteca.

    PubMed

    Suzzi, Giovanna; Schirone, Maria; Martuscelli, Maria; Gatti, Monica; Fornasari, Maria Emanuela; Neviani, Erasmo

    2003-04-01

    Manteca is a traditional milk product of southern Italy produced from whey deriving from Caciocavallo Podolico cheese-making. This study was undertaken to obtain more information about the microbiological properties of this product and particularly about the presence, metabolic activities, and technological significance of the different yeast species naturally occurring in Manteca. High numbers of yeasts were counted after 7 days ripening (10(4)-10(5) cfu g(-1)) and then decreased to 10(2) at the end. A total of 179 isolates were identified and studied for their phenotypic and genotypic characteristics. The most frequently encountered species were Trichosporon asahii (45), Candida parapsilosis (33), Rhodotorula mucilaginosa (32), Candida inconspicua (29). Some of these yeasts showed lipolytic activity (32 strains) and proteolytic activity (29 strains), NaCl resistance up to 10% and growth up to 45 degrees C (42 strains). Biogenic amines were formed by proteolytic strains, in particular phenylethylamine, putrescine and spermidine. Spermidine was produced by all the yeasts tested in this work, but only Trichosporon produced a great quantity of this compound. Histamine was not detectable. Caseinolytic activity was common to almost all strains, corresponding to the ability to efficiently split off amino-terminal amino acids. The highest and most constant activity expressed by all species was X-prolyl-dipeptidyl aminopeptidase. The findings suggest that the presence of yeasts may play a significant role in justifying interactions with lactic acid bacteria, and consequently with their metabolic activity in the definition of the peculiar characteristics of Manteca cheese.

  19. [Fructose transporter in yeasts].

    PubMed

    Lazar, Zbigniew; Dobrowolski, Adam; Robak, Małgorzata

    2014-01-01

    Study of hexoses transporter started with discovery of galactose permease in Saccharomyces cerevisiae. Glucose, fructose and mannose assimilation is assumed by numerous proteins encoded by different genes. To date over 20 hexoses transporters, belonging to Sugar Porter family and to Major Facilitator Superfamily, were known. Genome sequence analysis of Candida glabrata, Kluyveromyces lactis, Yarrowia lipolytica, S. cerevisaie and Debaryomyces hansenii reveled potential presence of 17-48 sugar porter proteins. Glucose transporters in S. cerevisiae have been already characterized. In this paper, hexoses transporters, responsible for assimilation of fructose by cells, are presented and compared. Fructose specific transporter are described for yeasts: Zygosaccharomyces rouxii, Zygosaccharomyces bailli, K. lactis, Saccharomyces pastorianus, S. cerevisiae winemaking strain and for fungus Botritys cinerea and human (Glut5p). Among six yeasts transporters, five are fructose specific, acting by facilitated diffusion or proton symport. Yeasts monosaccharides transporter studies allow understanding of sugars uptake and metabolism important aspects, even in higher eukaryotes cells.

  20. Yeast killer systems.

    PubMed Central

    Magliani, W; Conti, S; Gerloni, M; Bertolotti, D; Polonelli, L

    1997-01-01

    The killer phenomenon in yeasts has been revealed to be a multicentric model for molecular biologists, virologists, phytopathologists, epidemiologists, industrial and medical microbiologists, mycologists, and pharmacologists. The surprisingly widespread occurrence of the killer phenomenon among taxonomically unrelated microorganisms, including prokaryotic and eukaryotic pathogens, has engendered a new interest in its biological significance as well as its theoretical and practical applications. The search for therapeutic opportunities by using yeast killer systems has conceptually opened new avenues for the prevention and control of life-threatening fungal diseases through the idiotypic network that is apparently exploited by the immune system in the course of natural infections. In this review, the biology, ecology, epidemiology, therapeutics, serology, and idiotypy of yeast killer systems are discussed. PMID:9227858

  1. Evolutionary history of Ascomyceteous Yeasts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Yeasts are important for many industrial and biotechnological processes and show remarkable diversity despite morphological similarities. We have sequenced the genomes of 20 ascomyceteous yeasts of taxonomic and industrial importance including members of Saccharomycotina and Taphrinomycotina. A comp...

  2. L-arabinose fermenting yeast

    DOEpatents

    Zhang, Min; Singh, Arjun; Knoshaug, Eric; Franden, Mary Ann; Jarvis, Eric; Suominen, Pirkko

    2010-12-07

    An L-arabinose utilizing yeast strain is provided for the production of ethanol by introducing and expressing bacterial araA, araB and araD genes. L-arabinose transporters are also introduced into the yeast to enhance the uptake of arabinose. The yeast carries additional genomic mutations enabling it to consume L-arabinose, even as the only carbon source, and to produce ethanol. Methods of producing ethanol include utilizing these modified yeast strains. ##STR00001##

  3. Conversion of pentoses by yeasts

    SciTech Connect

    Gong, C.S.; Claypool, T.A.; Maun, C.M.; Mccracken, L.D.; Tsao, G.T.; Ueng, P.P.

    1983-01-01

    The utilization and conversion of D-xylose, D-xyulose, L-arabinose, and xylitol by yeast strains have been investigated with the following results: 1) The majority of yeasts tested utilize D-xylose and produce polyols, ethanol, and organic acids. The type and amount of products formed varies with the yeast strains used. The most commonly detected product is xylitol. 2) The majority of yeasts tested utilize D-xylulose aerobically and fermentatively to produce ethanol, xylitol D-arabitol, and organic acids. The type and amount of products varies depending upon the yeast strains used. 3) Xylitol is a poor carbon and energy source for most yeasts tested. Some yeast strains produce small amounts of ethanol from xylitol. 4) Most yeast strains utilize L-arabinose, and L-arabitol is the common product. Small amounts of ethanol are also produced by some yeast strains. 5) Of the four substrates examined, D-xylulose was the preferred substrate, followed by D-xylose, L-arabinose, and xylitol. 6) Mutant yeast strains that exhibit different metabolic product patterns can be induced and isolated from Candida sp. Saccharomyces cerevisiae, and other yeasts. These mutant strains can be used for ethanol production from D-xylose as well as for the study of metabolic regulation of pentose utilization in yeasts.

  4. Yeast Infection (Vaginal)

    MedlinePlus

    ... dose estrogen birth control pills or estrogen hormone therapy. Uncontrolled diabetes. Women with diabetes who have poorly controlled blood ... of yeast infections than women with well-controlled diabetes. Impaired ... such as from corticosteroid therapy or HIV infection — are more likely to get ...

  5. L-arabinose fermenting yeast

    SciTech Connect

    Zhang, Min; Singh, Arjun; Suominen, Pirkko; Knoshaug, Eric; Franden, Mary Ann; Jarvis, Eric

    2014-09-23

    An L-arabinose utilizing yeast strain is provided for the production of ethanol by introducing and expressing bacterial araA, araB and araD genes. L-arabinose transporters are also introduced into the yeast to enhance the uptake of arabinose. The yeast carries additional genomic mutations enabling it to consume L-arabinose, even as the only carbon source, and to produce ethanol. A yeast strain engineered to metabolize arabinose through a novel pathway is also disclosed. Methods of producing ethanol include utilizing these modified yeast strains.

  6. L-arabinose fermenting yeast

    DOEpatents

    Zhang, Min; Singh, Arjun; Suominen, Pirkko; Knoshaug, Eric; Franden, Mary Ann; Jarvis, Eric

    2013-02-12

    An L-arabinose utilizing yeast strain is provided for the production of ethanol by introducing and expressing bacterial araA, araB and araD genes. L-arabinose transporters are also introduced into the yeast to enhance the uptake of arabinose. The yeast carries additional genomic mutations enabling it to consume L-arabinose, even as the only carbon source, and to produce ethanol. A yeast strain engineered to metabolize arabinose through a novel pathway is also disclosed. Methods of producing ethanol include utilizing these modified yeast strains.

  7. Yeast ecology of Kombucha fermentation.

    PubMed

    Teoh, Ai Leng; Heard, Gillian; Cox, Julian

    2004-09-01

    Kombucha is a traditional fermentation of sweetened tea, involving a symbiosis of yeast species and acetic acid bacteria. Despite reports of different yeast species being associated with the fermentation, little is known of the quantitative ecology of yeasts in Kombucha. Using oxytetracycline-supplemented malt extract agar, yeasts were isolated from four commercially available Kombucha products and identified using conventional biochemical and physiological tests. During the fermentation of each of the four products, yeasts were enumerated from both the cellulosic pellicle and liquor of the Kombucha. The number and diversity of species varied between products, but included Brettanomyces bruxellensis, Candida stellata, Schizosaccharomyces pombe, Torulaspora delbrueckii and Zygosaccharomyces bailii. While these yeast species are known to occur in Kombucha, the enumeration of each species present throughout fermentation of each of the four Kombucha cultures demonstrated for the first time the dynamic nature of the yeast ecology. Kombucha fermentation is, in general, initiated by osmotolerant species, succeeded and ultimately dominated by acid-tolerant species.

  8. Mitochondrial inheritance in yeast.

    PubMed

    Westermann, Benedikt

    2014-07-01

    Mitochondria are the site of oxidative phosphorylation, play a key role in cellular energy metabolism, and are critical for cell survival and proliferation. The propagation of mitochondria during cell division depends on replication and partitioning of mitochondrial DNA, cytoskeleton-dependent mitochondrial transport, intracellular positioning of the organelle, and activities coordinating these processes. Budding yeast Saccharomyces cerevisiae has proven to be a valuable model organism to study the mechanisms that drive segregation of the mitochondrial genome and determine mitochondrial partitioning and behavior in an asymmetrically dividing cell. Here, I review past and recent advances that identified key components and cellular pathways contributing to mitochondrial inheritance in yeast. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. Guest Editors: Manuela Pereira and Miguel Teixeira.

  9. Extracellular Polysaccharides Produced by Yeasts and Yeast-Like Fungi

    NASA Astrophysics Data System (ADS)

    van Bogaert, Inge N. A.; de Maeseneire, Sofie L.; Vandamme, Erick J.

    Several yeasts and yeast-like fungi are known to produce extracellular polysaccharides. Most of these contain D-mannose, either alone or in combination with other sugars or phosphate. A large chemical and structural variability is found between yeast species and even among different strains. The types of polymers that are synthesized can be chemically characterized as mannans, glucans, phosphoman-nans, galactomannans, glucomannans and glucuronoxylomannans. Despite these differences, almost all of the yeast exopolysaccharides display some sort of biological activity. Some of them have already applications in chemistry, pharmacy, cosmetics or as probiotic. Furthermore, some yeast exopolysaccharides, such as pullulan, exhibit specific physico-chemical and rheological properties, making them useful in a wide range of technical applications. A survey is given here of the production, the characteristics and the application potential of currently well studied yeast extracellular polysaccharides.

  10. Necrosis in yeast.

    PubMed

    Eisenberg, Tobias; Carmona-Gutierrez, Didac; Büttner, Sabrina; Tavernarakis, Nektarios; Madeo, Frank

    2010-03-01

    Necrosis was long regarded as an accidental cell death process resulting from overwhelming cellular injury such as chemical or physical disruption of the plasma membrane. Such a definition, however, proved to be inapplicable to many necrotic scenarios. The discovery that genetic manipulation of several proteins either protected or enhanced necrotic cell death argued in favor of a regulated and hence programmed process, as it is the case for apoptosis. For more than a decade, yeast has served as a model for apoptosis research; recently, evidence accumulated that it also harbors a necrotic program. Here, we summarize the current knowledge about factors that control necrotic cell death in yeast. Mitochondria, aging and a low pH are positive regulators of this process while cellular polyamines (e.g. spermidine) and endonuclease G as well as homeostatic organelles like the vacuole or peroxisomes are potent inhibitors of necrosis. Physiological necrosis may stimulate intercellular signaling via the release of necrotic factors that promote viability of healthy cells and, thus, assure survival of the clone. Together, the data obtained in yeast argue for the existence of a necrotic program, which controls longevity and whose physiological function may thus be aging.

  11. Oleaginous yeasts from Ethiopia.

    PubMed

    Jiru, Tamene Milkessa; Abate, Dawit; Kiggundu, Nicholas; Pohl, Carolina; Groenewald, Marizeth

    2016-12-01

    Oleaginous microorganisms can produce high amounts of oil (>20 % of their biomass) under suitable cultivation conditions. In this research work 200 samples were collected from soil, plant surfaces (leaves, flowers and fruits), waste oils from traditional oil milling houses and dairy products (cheese, milk and yoghurt) in Ethiopia. Three hundred and forty yeast colonies were isolated from these samples. By applying Sudan III staining tests, 18 strains were selected as possible oleaginous yeasts. The 18 strains were identified and characterized for their lipid production as a feedstock for biodiesel production in the future. They were identified using morphological and physiological methods as well as sequencing the 3'end of the small-subunit rRNA gene, the internal transcribed spacer regions (ITS; ITS 1, ITS 2 and the intervening 5.8S rRNA gene), and the D1/D2 domain of the 26S rRNA gene. The 18 yeasts were identified as Cutaneotrichosporon curvatus (syn, Cryptococcus curvatus) (PY39), Rhodotorula kratochvilovae (syn, Rhodosporidium kratochvilovae) (SY89), Rhodotorula dairenensis (SY94) and Rhodotourula mucilaginosa (SY09, SY18, SY20, PY21, PY23, PY25, SY30, PY32, SY43, PY44, SY52, PY55, PY61, SY75 and PY86). Under nitrogen-limited cultivation conditions, R. mucilaginosa PY44 produced the highest biomass (15.10 ± 0.54 g/L), while R. mucilaginosa PY32 produced the lowest biomass (10.32 ± 0.18 g/L). The highest lipid yield of 6.87 ± 0.62 g/L and lipid content of 46.51 ± 0.70 % were attained by C. curvatus (syn, C. curvatus) PY39. On the other hand, R. mucilaginosa PY61 gave the lowest lipid yield (2.06 ± 0.52 g/L) and R. mucilaginosa SY52 gave the lowest lipid content of 16.99 ± 0.85 %. The results in this research work suggest that much more oleaginous yeasts can be isolated from Ethiopian environment. On the basis of their substantial lipid production abilities, the three oleaginous yeast strains PY39, SY89 and SY18 were selected and

  12. Production of astaxanthin from corn fiber as a value-added co-product of fuel ethanol fermentation.

    PubMed

    Nghiem, Nhuan P; Montanti, Justin; Johnston, David

    2009-05-01

    Five strains of the yeast Phaffia rhodozyma, NRRL Y-17268, NRRL Y-17270, ATCC 96594 (CBS 6938), ATCC 24202 (UCD 67-210), and ATCC 74219 (UBV-AX2) were tested for astaxanthin production using the major sugars derived from corn fiber. The sugars tested included glucose, xylose, and arabinose. All five strains were able to utilize the three sugars for astaxanthin production. Among them, ATCC 74219 was the best astaxanthin producer. Kinetics of sugar utilization of this strain was studied, both with the individual sugars and with their mixtures. Arabinose was found to give the highest astaxanthin yield. It also was observed that glucose at high concentrations suppressed utilization of the other two sugars. Corn fiber hydrolysate obtained by dilute sulfuric acid pretreatment and subsequent enzyme hydrolysis was tested for astaxanthin production by strain ATCC 74219. Dilution of the hydrolysate was necessary to allow growth and astaxanthin production. All the sugars in the hydrolysate diluted with two volumes of water were completely consumed. Astaxanthin yield of 0.82 mg/g total sugars consumed was observed.

  13. Genomics and the making of yeast biodiversity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Yeasts are unicellular fungi that do not form fruiting bodies. Although the yeast lifestyle has evolved multiple times, most known species belong to the subphylum Saccharomycotina (syn. Hemiascomycota, hereafter yeasts). This diverse group includes the premier eukaryotic model system, Saccharomyces ...

  14. Ethanol tolerance in yeasts.

    PubMed

    Casey, G P; Ingledew, W M

    1986-01-01

    It is now certain that the inherent ethanol tolerance of the Saccharomyces strain used is not the prime factor regulating the level of ethanol that can be produced in a high sugar brewing, wine, sake, or distillery fermentation. In fact, in terms of the maximum concentration that these yeasts can produce under batch (16 to 17% [v/v]) or fed-batch conditions, there is clearly no difference in ethanol tolerance. This is not to say, however, that under defined conditions there is no difference in ethanol tolerance among different Saccharomyces yeasts. This property, although a genetic determinant, is clearly influenced by many factors (carbohydrate level, wort nutrition, temperature, osmotic pressure/water activity, and substrate concentration), and each yeast strain reacts to each factor differently. This will indeed lead to differences in measured tolerance. Thus, it is extremely important that each of these be taken into consideration when determining "tolerance" for a particular set of fermentation conditions. The manner in which each alcohol-related industry has evolved is now known to have played a major role in determining traditional thinking on ethanol tolerance in Saccharomyces yeasts. It is interesting to speculate on how different our thinking on ethanol tolerance would be today if sake fermentations had not evolved with successive mashing and simultaneous saccharification and fermentation of rice carbohydrate, if distillers' worts were clarified prior to fermentation but brewers' wort were not, and if grape skins with their associated unsaturated lipids had not been an integral part of red wine musts. The time is now ripe for ethanol-related industries to take advantage of these findings to improve the economies of production. In the authors' opinion, breweries could produce higher alcohol beers if oxygenation (leading to unsaturated lipids) and "usable" nitrogen source levels were increased in high gravity worts. White wine fermentations could also, if

  15. Expanding the yeast prion world

    PubMed Central

    Suzuki, Genjiro; Tanaka, Motomasa

    2013-01-01

    Mammalian and fungal prion proteins form self-perpetuating β-sheet-rich fibrillar aggregates called amyloid. Prion inheritance is based on propagation of the regularly oriented amyloid structures of the prion proteins. All yeast prion proteins identified thus far contain aggregation-prone glutamine/asparagine (Gln/Asn)-rich domains, although the mammalian prion protein and fungal prion protein HET-s do not contain such sequences. In order to fill this gap, we searched for novel yeast prion proteins lacking Gln/Asn-rich domains via a genome-wide screen based on cross-seeding between two heterologous proteins and identified Mod5, a yeast tRNA isopentenyltransferase, as a novel non-Gln/Asn-rich yeast prion protein. Mod5 formed self-propagating amyloid fibers in vitro and the introduction of Mod5 amyloids into non-prion yeast induced dominantly and cytoplasmically heritable prion state [MOD+], which harbors aggregates of endogenous Mod5. [MOD+] yeast showed an increased level of membrane lipid ergosterol and acquired resistance to antifungal agents. Importantly, enhanced de novo formation of [MOD+] was observed when non-prion yeast was grown under selective pressures from antifungal drugs. Our findings expand the family of yeast prions to non-Gln/Asn-rich proteins and reveal the acquisition of a fitness advantage for cell survival through active prion conversion. PMID:23117914

  16. New and emerging yeast pathogens.

    PubMed Central

    Hazen, K C

    1995-01-01

    The most common yeast species that act as agents of human disease are Candida albicans, Candida tropicalis, Candida glabrata, Candida parapsilosis, and Cryptococcus neoformans. The incidence of infections by other yeasts has increased during the past decade. The most evident emerging pathogens are Malassezia furfur, Trichosporon beigelii, Rhodotorula species, Hansenula anomala, Candida lusitaniae, and Candida krusei. Organisms once considered environmental contaminants or only industrially important, such as Candida utilis and Candida lipolytica, have now been implicated as agents of fungemia, onychomycosis, and systemic disease. The unusual yeasts primarily infect immunocompromised patients, newborns, and the elderly. The role of central venous catheter removal and antifungal therapy in patient management is controversial. The antibiograms of the unusual yeasts range from resistant to the most recent azoles and amphotericin B to highly susceptible to all antifungal agents. Current routine methods for yeast identification may be insufficient to identify the unusual yeasts within 2 days after isolation. The recognition of unusual yeasts as agents of sometimes life-threatening infection and their unpredictable antifungal susceptibilities increase the burden on the clinical mycology laboratory to pursue complete species identification and MIC determinations. Given the current and evolving medical practices for management of seriously ill patients, further evaluations of the clinically important data about these yeasts are needed. PMID:8665465

  17. Yeast two-hybrid screen.

    PubMed

    Makuch, Lauren

    2014-01-01

    Yeast two-hybrid is a method for screening large numbers of gene products (encoded by cDNA libraries) for their ability to interact with a protein of interest. This system can also be used for characterizing and manipulating candidate protein: protein interactions. Interactions between proteins are monitored by the growth of yeast plated on selective media.

  18. From yeast genetics to biotechnology.

    PubMed

    Maráz, Anna

    2002-01-01

    Roots of classical yeast genetics go back to the early work of Lindegreen in the 1930s, who studied thallism, sporulation and inheritance of wine yeast strains belonging to S. cerevisiae. Consequent mutation and hybridization of heterothallic S. cerevisae strains resulted in the discovery of life cycle and mating type system, as well as construction of the genetic map. Elaboration of induced mutation and controlled hybridization of yeast strains opened up new possibilities for the genetic analysis of technologically important properties and for the production of improved industrial strains, but a big drawback was the widely different genetic properties of laboratory and industrial yeast strains. Genetic analysis and mapping of industrial strains were generally hindered because of homothallism, poor sporulation and/or low spore viability of brewing and wine yeast strains [1, 2]. In spite of this, there are a few examples of the application of sexual hybridization in the study of genetic control of important technological properties, e.g. sugar utilization, flocculation and flavor production in brewing yeast strains [3] or in the improvement of ethanol producing S. cerevisiae strains [4]. Rare mating and application of karyogamy deficient (kar-) mutants also proved useful in strain improvement [5]. Importance of yeasts in biotechnology is enormous. This includes food and beverage fermentation processes where a wide range of yeast species are playing role, but S. cerevisiae is undoubtedly the most important species among them. New biotechnology is aiming to improve these technologies, but besides this, a completely new area of yeast utilization has been emerged, especially in the pharmaceutical and medical areas. Without decreasing the importance of S. cerevisiae, numerous other yeast species, e.g. Kluyveromyces lactis, Hansenula polymorpha, Pichia pastoris, Schizosaccharomyces pombe and Yarrowia lipolytica have gained increasing potentialities in the modern

  19. Agriculturally important yeasts: Biological control of field and postharvest diseases using yeast antagonists, and yeasts as pathogens of plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two important agricultural aspects of yeasts, control of plant diseases through application of yeasts as the control agent, and yeasts that are plant pathogens are reviewed. Yeasts as biocontrol organisms are presented first, followed by a discussion of some of the more common plant pathogenic yeas...

  20. Bioprotective Role of Yeasts

    PubMed Central

    Muccilli, Serena; Restuccia, Cristina

    2015-01-01

    The yeasts constitute a large group of microorganisms characterized by the ability to grow and survive in different and stressful conditions and then to colonize a wide range of environmental and human ecosystems. The competitive traits against other microorganisms have attracted increasing attention from scientists, who proposed their successful application as bioprotective agents in the agricultural, food and medical sectors. These antagonistic activities rely on the competition for nutrients, production and tolerance of high concentrations of ethanol, as well as the synthesis of a large class of antimicrobial compounds, known as killer toxins, which showed clearly a large spectrum of activity against food spoilage microorganisms, but also against plant, animal and human pathogens. This review describes the antimicrobial mechanisms involved in the antagonistic activity, their applications in the processed and unprocessed food sectors, as well as the future perspectives in the development of new bio-drugs, which may overcome the limitations connected to conventional antimicrobial and drug resistance. PMID:27682107

  1. BIOSYNTHESIS OF YEAST CAROTENOIDS

    PubMed Central

    Simpson, Kenneth L.; Nakayama, T. O. M.; Chichester, C. O.

    1964-01-01

    Simpson, Kenneth L. (University of California, Davis), T. O. M. Nakayama, and C. O. Chichester. Biosynthesis of yeast carotenoids. J. Bacteriol. 88:1688–1694. 1964.—The biosynthesis of carotenoids was followed in Rhodotorula glutinis and in a new strain, 62-506. The treatment of the growing cultures by methylheptenone, or ionone, vapors permitted observations of the intermediates in the biosynthetic pathway. On the basis of concentration changes and accumulation in blocked pathways, the sequence of carotenoid formation is postulated as phytoene, phytofluene, ζ-carotene, neurosporene, β-zeacarotene, γ-carotene, torulin, a C40 aldehyde, and torularhodin. Torulin and torularhodin were established as the main carotenoids of 62-506. PMID:14240958

  2. Interaction Between Yeasts and Zinc

    NASA Astrophysics Data System (ADS)

    Nicola, Raffaele De; Walker, Graeme

    Zinc is an essential trace element in biological systems. For example, it acts as a cellular membrane stabiliser, plays a critical role in gene expression and genome modification and activates nearly 300 enzymes, including alcohol dehydrogenase. The present chapter will be focused on the influence of zinc on cell physiology of industrial yeast strains of Saccharomyces cerevisiae, with special regard to the uptake and subsequent utilisation of this metal. Zinc uptake by yeast is metabolism-dependent, with most of the available zinc translocated very quickly into the vacuole. At cell division, zinc is distributed from mother to daughter cells and this effectively lowers the individual cellular zinc concentration, which may become zinc depleted at the onset of the fermentation. Zinc influences yeast fermentative performance and examples will be provided relating to brewing and wine fermentations. Industrial yeasts are subjected to several stresses that may impair fermentation performance. Such stresses may also impact on yeast cell zinc homeostasis. This chapter will discuss the practical implications for the correct management of zinc bioavailability for yeast-based biotechnologies aimed at improving yeast growth, viability, fermentation performance and resistance to environmental stresses

  3. Oral yeast colonization throughout pregnancy

    PubMed Central

    Rio, Rute; Simões-Silva, Liliana; Garro, Sofia; Silva, Mário-Jorge; Azevedo, Álvaro

    2017-01-01

    Background Recent studies suggest that placenta may harbour a unique microbiome that may have origin in maternal oral microbiome. Although the major physiological and hormonal adjustments observed in pregnant women lead to biochemical and microbiological modifications of the oral environment, very few studies evaluated the changes suffered by the oral microbiota throughout pregnancy. So, the aim of our study was to evaluate oral yeast colonization throughout pregnancy and to compare it with non-pregnant women. Material and Methods The oral yeast colonization was assessed in saliva of 30 pregnant and non-pregnant women longitudinally over a 6-months period. Demographic information was collected, a non-invasive intra-oral examination was performed and saliva flow and pH were determined. Results Pregnant and non-pregnant groups were similar regarding age and level of education. Saliva flow rate did not differ, but saliva pH was lower in pregnant than in non-pregnant women. Oral yeast prevalence was higher in pregnant than in non-pregnant women, either in the first or in the third trimester, but did not attain statistical significance. In individuals colonized with yeast, the total yeast quantification (Log10CFU/mL) increase from the 1st to the 3rd trimester in pregnant women, but not in non-pregnant women. Conclusions Pregnancy may favour oral yeast growth that may be associated with an acidic oral environment. Key words:Oral yeast, fungi, pregnancy, saliva pH. PMID:28160578

  4. [Thermoresistance in Saccharomyces cerevisiae yeasts].

    PubMed

    Kaliuzhin, V A

    2011-01-01

    Under natural conditions, yeast Saccharomyces cerevisiae reproduce, as a rule, on the surface of solid or liquid medium. Thus, life cycle of yeast populations is substantially influenced by diurnal changes in ambient temperature. The pattern in the response of unrestricted yeast S. cerevisiae culture to changes in the temperature of cultivation is revealed experimentally. Yeast population, in the absence of environmental constraints on the functioning of cell chemosmotic bioenergetic system, demonstrates the ability of thermoresistance when the temperature of cultivation switches from the range of 12-36 degrees C to 37.5-40 degrees C. During the transient period that is associated with the temperature switching and lasts from 1 to 4 turnover cycles, yeast reproduction rate remains 1.5-2 times higher than under stationary conditions. This is due to evolutionary acquired adaptive activity of cell chemosmotic system. After the adaptive resources exhausting, yeast thermoresistance fully recovers at the temperature range of 12-36 degrees C within one generation time under conditions of both restricted and unrestricted nourishment. Adaptive significance of such thermoresistance seems obvious enough--it allows maintaining high reproduction rate in yeast when ambient temperature is reaching a brief maximum shortly after noon.

  5. Nitric oxide signaling in yeast.

    PubMed

    Astuti, Rika Indri; Nasuno, Ryo; Takagi, Hiroshi

    2016-11-01

    As a cellular signaling molecule, nitric oxide (NO) is widely conserved from microorganisms, such as bacteria, yeasts, and fungi, to higher eukaryotes including plants and mammals. NO is mainly produced by NO synthase (NOS) or nitrite reductase (NIR) activity. There are several NO detoxification systems, including NO dioxygenase (NOD) and S-nitrosoglutathione reductase (GSNOR). NO homeostasis based on the balance between NO synthesis and degradation is important for the regulation of its physiological functions because an excess level of NO causes nitrosative stress due to the high reactivity of NO and NO-derived compounds. In yeast, NO may be involved in stress responses, but NO and its signaling have been poorly understood due to the lack of mammalian NOS orthologs in the genome. Even though the activities of NOS and NIR have been observed in yeast cells, the gene encoding NOS and the NO production mechanism catalyzed by NIR remain unclear. On the other hand, yeast cells employ NOD and GSNOR to maintain an intracellular redox balance following endogenous NO production, exogenous NO treatment, or environmental stresses. This article reviews NO metabolism (synthesis, degradation) and its regulation in yeast. The physiological roles of NO in yeast, including the oxidative stress response, are also discussed here. Such investigations into NO signaling are essential for understanding the NO-dependent genetic and physiological modulations. In addition to being responsible for the pathology and pharmacology of various degenerative diseases, NO signaling may be a potential target for the construction and engineering of industrial yeast strains.

  6. Lager Yeast Comes of Age

    PubMed Central

    2014-01-01

    Alcoholic fermentations have accompanied human civilizations throughout our history. Lager yeasts have a several-century-long tradition of providing fresh beer with clean taste. The yeast strains used for lager beer fermentation have long been recognized as hybrids between two Saccharomyces species. We summarize the initial findings on this hybrid nature, the genomics/transcriptomics of lager yeasts, and established targets of strain improvements. Next-generation sequencing has provided fast access to yeast genomes. Its use in population genomics has uncovered many more hybridization events within Saccharomyces species, so that lager yeast hybrids are no longer the exception from the rule. These findings have led us to propose network evolution within Saccharomyces species. This “web of life” recognizes the ability of closely related species to exchange DNA and thus drain from a combined gene pool rather than be limited to a gene pool restricted by speciation. Within the domesticated lager yeasts, two groups, the Saaz and Frohberg groups, can be distinguished based on fermentation characteristics. Recent evidence suggests that these groups share an evolutionary history. We thus propose to refer to the Saaz group as Saccharomyces carlsbergensis and to the Frohberg group as Saccharomyces pastorianus based on their distinct genomes. New insight into the hybrid nature of lager yeast will provide novel directions for future strain improvement. PMID:25084862

  7. Centromeric chromatin in fission yeast.

    PubMed

    Partridge, Janet F

    2008-05-01

    A fundamental requirement for life is the ability of cells to divide properly and to pass on to their daughters a full complement of genetic material. The centromere of the chromosome is essential for this process, as it provides the DNA sequences on which the kinetochore (the proteinaceous structure that links centromeric DNA to the spindle microtubules) assembles to allow segregation of the chromosomes during mitosis. It has long been recognized that kinetochore assembly is subject to epigenetic control, and deciphering how centromeres promote faithful chromosome segregation provides a fascinating intellectual challenge. This challenge is made more difficult by the scale and complexity of DNA sequences in metazoan centromeres, thus much research has focused on dissecting centromere function in the single celled eukaryotic yeasts. Interestingly, in spite of similarities in the genome size of budding and fission yeasts, they seem to have adopted some striking differences in their strategy for passing on their chromosomes. Budding yeast have "point" centromeres, where a 125 base sequence is sufficient for mitotic propagation, whereas fission yeast centromeres are more reminiscent of the large repetitive centromeres of metazoans. In addition, the centromeric heterochromatin which coats centromeric domains of fission yeast and metazoan centromeres and is critical for their function, is largely absent from budding yeast centromeres. This review focuses on the assembly and maintenance of centromeric chromatin in the fission yeast.

  8. 21 CFR 172.896 - Dried yeasts.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Dried yeasts. 172.896 Section 172.896 Food and... Multipurpose Additives § 172.896 Dried yeasts. Dried yeast (Saccharomyces cerevisiae and Saccharomyces fragilis) and dried torula yeast (Candida utilis) may be safely used in food provided the total folic...

  9. 21 CFR 172.896 - Dried yeasts.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Dried yeasts. 172.896 Section 172.896 Food and... Multipurpose Additives § 172.896 Dried yeasts. Dried yeast (Saccharomyces cerevisiae and Saccharomyces fragilis) and dried torula yeast (Candida utilis) may be safely used in food provided the total folic...

  10. 21 CFR 172.896 - Dried yeasts.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Dried yeasts. 172.896 Section 172.896 Food and... Multipurpose Additives § 172.896 Dried yeasts. Dried yeast (Saccharomyces cerevisiae and Saccharomyces fragilis) and dried torula yeast (Candida utilis) may be safely used in food provided the total folic...

  11. 21 CFR 172.896 - Dried yeasts.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Dried yeasts. 172.896 Section 172.896 Food and... Multipurpose Additives § 172.896 Dried yeasts. Dried yeast (Saccharomyces cerevisiae and Saccharomyces fragilis) and dried torula yeast (Candida utilis) may be safely used in food provided the total folic...

  12. 21 CFR 172.896 - Dried yeasts.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Dried yeasts. 172.896 Section 172.896 Food and... PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Multipurpose Additives § 172.896 Dried yeasts. Dried yeast (Saccharomyces cerevisiae and Saccharomyces fragilis) and dried torula yeast (Candida...

  13. Marine yeast isolation and industrial application

    PubMed Central

    Zaky, Abdelrahman Saleh; Tucker, Gregory A; Daw, Zakaria Yehia; Du, Chenyu

    2014-01-01

    Over the last century, terrestrial yeasts have been widely used in various industries, such as baking, brewing, wine, bioethanol and pharmaceutical protein production. However, only little attention has been given to marine yeasts. Recent research showed that marine yeasts have several unique and promising features over the terrestrial yeasts, for example higher osmosis tolerance, higher special chemical productivity and production of industrial enzymes. These indicate that marine yeasts have great potential to be applied in various industries. This review gathers the most recent techniques used for marine yeast isolation as well as the latest applications of marine yeast in bioethanol, pharmaceutical and enzyme production fields. PMID:24738708

  14. Marine yeasts and their applications in mariculture

    NASA Astrophysics Data System (ADS)

    Zhenming, Chi; Zhiqiang, Liu; Lingmei, Gao; Fang, Gong; Chunling, Ma; Xianghong, Wang; Haifeng, Li

    2006-07-01

    The terrestrial yeasts have been receiving great attention in science and industry for over one hundred years because they can produce many kinds of bioactive substances. However, little is known about the bioactive substances of marine yeasts. In recent years, it has been found that marine yeasts have wide applications in mariculture and other fields. Therefore, marine yeasts, the bioactive substances from them and the applications of marine yeasts themselves and the bioactive substances they produced are reviewed in this paper.

  15. The Yeast Sphingolipid Signaling Landscape

    PubMed Central

    Montefusco, David J.; Matmati, Nabil

    2014-01-01

    Sphingolipids are recognized as signaling mediators in a growing number of pathways, and represent potential targets to address many diseases. The study of sphingolipid signaling in yeast has created a number of breakthroughs in the field, and has the potential to lead future advances. The aim of this article is to provide an inclusive view of two major frontiers in yeast sphingolipid signaling. In the first section, several key studies in the field of sphingolipidomics are consolidated to create a yeast sphingolipidome that ranks nearly all known sphingolipid species by their level in a resting yeast cell. The second section presents an overview of most known phenotypes identified for sphingolipid gene mutants, presented with the intention of illuminating not yet discovered connections outside and inside of the field. PMID:24220500

  16. Assimilation of nitrate by yeasts.

    PubMed

    Siverio, José M

    2002-08-01

    Nitrate assimilation has received much attention in filamentous fungi and plants but not so much in yeasts. Recently the availability of classical genetic and molecular biology tools for the yeast Hansenula polymorpha has allowed the advance of the study of this metabolic pathway in yeasts. The genes YNT1, YNR1 and YNI1, encoding respectively nitrate transport, nitrate reductase and nitrite reductase, have been cloned, as well as two other genes encoding transcriptional regulatory factors. All these genes lie closely together in a cluster. Transcriptional regulation is the main regulatory mechanism that controls the levels of the enzymes involved in nitrate metabolism although other mechanisms may also be operative. The process involved in the sensing and signalling of the presence of nitrate in the medium is not well understood. In this article the current state of the studies of nitrate assimilation in yeasts as well as possible venues for future research are reviewed.

  17. Yeasts preservation: alternatives for lyophilisation.

    PubMed

    Nyanga, Loveness K; Nout, Martinus J R; Smid, Eddy J; Boekhout, Teun; Zwietering, Marcel H

    2012-11-01

    The aim of the study was to compare the effect of two low-cost, low technology traditional methods for drying starter cultures with standard lyophilisation. Lyophilised yeast cultures and yeast cultures preserved in dry rice cakes and dry plant fibre strands were examined for viable cell counts during 6 months storage at 4 and 25 °C. None of the yeast cultures showed a significant loss in viable cell count during 6 months of storage at 4 °C upon lyophilisation and preservation in dry rice cakes. During storage at 25 °C in the dark, yeast cultures preserved in dry rice cakes, and lyophilised cultures of Saccharomyces cerevisiae and Issatchenkia orientalis showed no significant loss of viable cells up to 4 months of storage. Yeast cultures preserved in dry plant fibre strands had the greatest loss of viable count during the 6 months of storage at 25 °C. Preservation of yeasts cultures in dry rice cakes provided better survival during storage at 4 °C than lyophilisation. The current study demonstrated that traditional methods can be useful and effective for starter culture preservation in small-scale, low-tech applications.

  18. Biotechnological Applications of Dimorphic Yeasts

    NASA Astrophysics Data System (ADS)

    Doiphode, N.; Joshi, C.; Ghormade, V.; Deshpande, M. V.

    The dimorphic yeasts have the equilibrium between spherical growth (budding) and polarized (hyphal or pseudohyphal tip elongation) which can be triggered by change in the environmental conditions. The reversible growth phenomenon has made dimorphic yeasts as an useful model to understand fungal evolution and fungal differentiation, in general. In nature dimorphism is clearly evident in plant and animal fungal pathogens, which survive and most importantly proliferate in the respective hosts. However, number of organisms with no known pathogenic behaviour also show such a transition, which can be exploited for the technological applications due to their different biochemical make up under different morphologies. For instance, chitin and chitosan production using dimorphic Saccharomyces, Mucor, Rhizopus and Benjaminiella, oil degradation and biotransformation with yeast-form of Yarrowia species, bioremediation of organic pollutants, exopolysac-charide production by yeast-phase of Aureobasidium pullulans, to name a few. Myrothecium verrucaria can be used for seed dressing in its yeast form and it produces a mycolytic enzyme complex in its hyphal-form for the biocontrol of fungal pathogens, while Beauveria bassiana and other entomopathogens kill the insect pest by producing yeast- like cells in the insect body. The form-specific expression of protease, chitinase, lipase, ornithine decarboxylase, glutamate dehydrogenases, etc. make Benjaminiella poitrasii, Basidiobolus sp., and Mucor rouxii strains important in bioremediation, nanobiotechnology, fungal evolution and other areas.

  19. Determination of astaxanthin stereoisomers and colour attributes in flesh of rainbow trout (Oncorhynchus mykiss) as a tool to distinguish the dietary pigmentation source.

    PubMed

    Moretti, V M; Mentasti, T; Bellagamba, F; Luzzana, U; Caprino, F; Turchini, G M; Giani, I; Valfrè, F

    2006-11-01

    The presence of carotenoids in animal tissue reflects their sources along the food chain. Astaxanthin, the main carotenoid used for salmonid pigmentation, is usually included in the feed as a synthetic product. However, other dietary sources of astaxanthin such as shrimp or krill wastes, algae meal or yeasts are also available on the market. Astaxanthin possesses two identical asymmetric atoms at C-3 and C-3' making possible three optical isomers with all-trans configuration of the chain: 3S,3'S, 3R,3'S, and 3R,3'R. The distribution of the isomers in natural astaxanthin differs from that of the synthetic product. This latter is a racemic mixture, with a typical ratio of 1:2:1 (3S,3'S:3R,3'S:3R,3'R), while astaxanthin from natural sources has a variable distribution of the isomers deriving from the different biological organism that synthesized it. The high-performance liquid chromatographic (HPLC) analysis of all-trans isomers of astaxanthin was performed in different pigment sources, such as red yeast Phaffia rhodozyma, alga meal Haematococcus pluvialis, krill meal and oil, and shrimp meal. With the aim to investigate astaxanthin isomer ratios in flesh of fish fed different carotenoid sources, three groups of rainbow trout were fed for 60 days diets containing astaxanthin from synthetic source, H. pluvialis algae meal and P. rhodozyma red yeast. Moreover, the distribution of optical isomers of astaxanthin in trout purchased on the Italian market was investigated. A characteristic distribution of astaxanthin stereoisomers was detected for each pigment sources and such distribution was reproduced in the flesh of trout fed with that source. Colour values measured in different sites of fillet of rainbow trout fed with different pigment sources showed no significant differences. Similarly, different sources of pigment (natural or synthetic) produced colour values of fresh fillet with no relevant or significant differences. The coefficient of distance computed amongst

  20. Red Yeast Rice

    PubMed Central

    Nguyen, Thu; Karl, Mitchell; Santini, Antonello

    2017-01-01

    Red yeast rice (RYR), produced by the fermentation of the Monascus purpureus mold, has been used for a long time in Asian cuisine and traditional medicine. It consists of multiple bioactive substances, including monacolins, which potentially can be used as a nutraceutical. Monacolin K, which is chemically identical to lovastatin, has been recognized as responsible for the cholesterol-reducing effect of this compound. While the European Food Safety Authority maintains that the use of monacolin K from RYR preparations of at least 10 mg can produce a normal blood cholesterol level, the United States Food and Drug Administration considers monacolin K, due to its similarity with lovastatin, an unapproved drug, and therefore marketing of products that label the monacolin content is prohibited. This mini-review summarizes the benefit of RYR in hyperlipidemia, maintains RYR use as a food, and addresses the importance of regulation regarding RYR and the need for clinical data and clear label information for consumers with reference to a toxin-free, non-augmented, standardized amount of monacolins. PMID:28257063

  1. Metabolic regulation of yeast

    NASA Astrophysics Data System (ADS)

    Fiechter, A.

    1982-12-01

    Metabolic regulation which is based on endogeneous and exogeneous process variables which may act constantly or time dependently on the living cell is discussed. The observed phenomena of the regulation are the result of physical, chemical, and biological parameters. These parameters are identified. Ethanol is accumulated as an intermediate product and the synthesis of biomass is reduced. This regulatory effect of glucose is used for the aerobic production of ethanol. Very high production rates are thereby obtained. Understanding of the regulation mechanism of the glucose effect has improved. In addition to catabolite repression, several other mechanisms of enzyme regulation have been described, that are mostly governed by exogeneous factors. Glucose also affects the control of respiration in a third class of yeasts which are unable to make use of ethanol as a substrate for growth. This is due to the lack of any anaplerotic activity. As a consequence, diauxic growth behavior is reduced to a one-stage growth with a drastically reduced cell yield. The pulse chemostat technique, a systematic approach for medium design is developed and medium supplements that are essential for metabolic control are identified.

  2. Yeast Genetics and Biotechnological Applications

    NASA Astrophysics Data System (ADS)

    Mishra, Saroj; Baranwal, Richa

    Yeast can be recognized as one of the very important groups of microorganisms on account of its extensive use in the fermentation industry and as a basic eukaryotic model cellular system. The yeast Saccharomyces cerevisiae has been extensively used to elucidate the genetics and regulation of several key functions in the cell such as cell mating, electron transport chain, protein trafficking, cell cycle events and others. Even before the genome sequence of the yeast was out, the structural organization and function of several of its genes was known. With the availability of the origin of replication from the 2 μm plasmid and the development of transformation system, it became the host of choice for expression of a number of important proteins. A large number of episomal and integrative shuttle vectors are available for expression of mammalian proteins. The latest developments in genomics and micro-array technology have allowed investigations of individual gene function by site-specific deletion method. The application of metabolic profiling has also assisted in understanding the cellular network operating in this yeast. This chapter is aimed at reviewing the use of this system as an experimental tool for conducting classical genetics. Various vector systems available, foreign genes expressed and the limitations as a host will be discussed. Finally, the use of various yeast enzymes in biotechnology sector will be reviewed.

  3. The intronome of budding yeasts.

    PubMed

    Neuvéglise, Cécile; Marck, Christian; Gaillardin, Claude

    2011-01-01

    Whatever their abundance in genomes, spliceosomal introns are the signature of eukaryotic genes. The sequence of Saccharomyces cerevisiae, achieved fifteen years ago, revealed that this yeast has very few introns, but conserved intron boundaries typical for an intron definition mechanism. With the improvement and the development of new sequencing technologies, yeast genomes have been extensively sequenced during the last decade. We took advantage of this plethora of data to compile and assess the intron content of the protein-coding genes of 13 genomes representative of the evolution of hemiascomycetous yeasts. We first observed that intron paucity is a general rule and that the fastest evolving genomes tend to lose their introns more rapidly (e.g. S. cerevisiae versus Yarrowia lipolytica). Noticeable differences were also confirmed for 5' splice sites and branch point sites (BP) as well as for the relative position of the BP. These changes seemed to be correlated with the lineage specific evolution of splicing factors.

  4. Yeast Can Affect Behavior and Learning.

    ERIC Educational Resources Information Center

    Crook, William G.

    1984-01-01

    A pediatrician recounts his experiences in diagnosing and treating allergies to common yeast germs that may result in behavior and learning problems. He lists characteristics that may predispose children to yeast-connected health problems. (CL)

  5. Genomic evolution of the ascomycetous yeasts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Yeasts are important for industrial and biotechnological processes and show remarkable metabolic and phylogenetic diversity despite morphological similarities. We have sequenced the genomes of 16 ascomycete yeasts of taxonomic and industrial importance including members of Saccharomycotina and Taphr...

  6. Chromatin and Transcription in Yeast

    PubMed Central

    Rando, Oliver J.; Winston, Fred

    2012-01-01

    Understanding the mechanisms by which chromatin structure controls eukaryotic transcription has been an intense area of investigation for the past 25 years. Many of the key discoveries that created the foundation for this field came from studies of Saccharomyces cerevisiae, including the discovery of the role of chromatin in transcriptional silencing, as well as the discovery of chromatin-remodeling factors and histone modification activities. Since that time, studies in yeast have continued to contribute in leading ways. This review article summarizes the large body of yeast studies in this field. PMID:22345607

  7. Advances in yeast genome engineering.

    PubMed

    David, Florian; Siewers, Verena

    2015-02-01

    Genome engineering based on homologous recombination has been applied to yeast for many years. However, the growing importance of yeast as a cell factory in metabolic engineering and chassis in synthetic biology demands methods for fast and efficient introduction of multiple targeted changes such as gene knockouts and introduction of multistep metabolic pathways. In this review, we summarize recent improvements of existing genome engineering methods, the development of novel techniques, for example for advanced genome redesign and evolution, and the importance of endonucleases as genome engineering tools.

  8. Mitochondrial inheritance in budding yeast.

    PubMed

    Boldogh, I R; Yang, H C; Pon, L A

    2001-06-01

    During the past decade significant advances were made toward understanding the mechanism of mitochondrial inheritance in the yeast Saccharomyces cerevisiae. A combination of genetics, cell-free assays and microscopy has led to the discovery of a great number of components. These fall into three major categories: cytoskeletal elements, mitochondrial membrane components and regulatory proteins. These proteins mediate activities, including movement of mitochondria from mother cells to buds, segregation of mitochondria and mitochondrial DNA, and equal distribution of the organelle between mother cells and buds during yeast cell division.

  9. Yeast: A Research Organism for Teaching Genetics.

    ERIC Educational Resources Information Center

    Manney, Thomas R.; Manney, Monta L.

    1992-01-01

    Explains why laboratory strains of bakers yeast, Saccharomyces cerevisiae, are particularly suited for classroom science activities. Describes the sexual life cycle of yeast and the genetic system with visible mutations. Presents an overview of activities that can be done with yeast and gives a source for teachers to obtain more information. (PR)

  10. Comparative Evaluation of the BD Phoenix Yeast ID Panel and Remel RapID Yeast Plus System for Yeast Identification.

    PubMed

    Grant, Michelle L; Parajuli, Shobha; Deleon-Gonsalves, Raquel; Potula, Raghava; Truant, Allan L

    2016-01-01

    Becton Dickinson Phoenix Yeast ID Panel was compared to the Remel RapID Yeast Plus System using 150 recent clinical yeast isolates and the API 20C AUX system to resolve discrepant results. The concordance rate between the Yeast ID Panel and the RapID Yeast Plus System (without arbitration) was 93.3% with 97.3% (146/150) and 95.3% (143/150) of the isolates correctly identified by the Becton Dickinson Phoenix and the Remel RapID, respectively, with arbitration.

  11. Comparative Evaluation of the BD Phoenix Yeast ID Panel and Remel RapID Yeast Plus System for Yeast Identification

    PubMed Central

    Grant, Michelle L.; Parajuli, Shobha; Deleon-Gonsalves, Raquel; Potula, Raghava; Truant, Allan L.

    2016-01-01

    Becton Dickinson Phoenix Yeast ID Panel was compared to the Remel RapID Yeast Plus System using 150 recent clinical yeast isolates and the API 20C AUX system to resolve discrepant results. The concordance rate between the Yeast ID Panel and the RapID Yeast Plus System (without arbitration) was 93.3% with 97.3% (146/150) and 95.3% (143/150) of the isolates correctly identified by the Becton Dickinson Phoenix and the Remel RapID, respectively, with arbitration. PMID:27366167

  12. Immobilized yeast for alcohol production

    SciTech Connect

    Not Available

    1982-02-03

    Construction of a pilot alcohol plant has been completed in Japan to test a new idea in fermentation that could cut the time required from three or four days to several hours. According to developers, the key is an unidentified radiation-cured polymer that is used to immobilize yeast, permitting the process to run continuously.

  13. Yeast as factory and factotum.

    PubMed

    Dixon, B

    2000-02-01

    After centuries of vigorous activity in making fine wines, beers and breads, Saccharomyces cerevisiae is now acquiring a rich new portfolio of skills, bestowed by genetic manipulation. As shown in a recent shop-window of research supported by the European Commission, yeasts will soon be benefiting industries as diverse as fish farming, pharmaceuticals and laundering.

  14. Overexpression of multisubunit replication factors in yeast.

    PubMed

    Burgers, P M

    1999-07-01

    Facile genetic and biochemical manipulation coupled with rapid cell growth and low cost of growth media has established the yeast Saccharomyces cerevisiae as a versatile workhorse. This article describes the use of yeast expression systems for the overproduction of complex multipolypeptide replication factors. The regulated overexpression of these factors in yeast provides for a readily accessible and inexpensive source of these factors in large quantities. The methodology is illustrated with the five-subunit replication factor C. Whole-cell extracts are prepared by blending yeast cells with glass beads or frozen yeast with dry ice. Procedures are described that maximize the yield of these factors while minimizing proteolytic degradation.

  15. The wine and beer yeast Dekkera bruxellensis.

    PubMed

    Schifferdecker, Anna Judith; Dashko, Sofia; Ishchuk, Olena P; Piškur, Jure

    2014-09-01

    Recently, the non-conventional yeast Dekkera bruxellensis has been gaining more and more attention in the food industry and academic research. This yeast species is a distant relative of Saccharomyces cerevisiae and is especially known for two important characteristics: on the one hand, it is considered to be one of the main spoilage organisms in the wine and bioethanol industry; on the other hand, it is 'indispensable' as a contributor to the flavour profile of Belgium lambic and gueuze beers. Additionally, it adds to the characteristic aromatic properties of some red wines. Recently this yeast has also become a model for the study of yeast evolution. In this review we focus on the recently developed molecular and genetic tools, such as complete genome sequencing and transformation, to study and manipulate this yeast. We also focus on the areas that are particularly well explored in this yeast, such as the synthesis of off-flavours, yeast detection methods, carbon metabolism and evolutionary history.

  16. Mycotoxins - prevention and decontamination by yeasts.

    PubMed

    Pfliegler, Walter P; Pusztahelyi, Tünde; Pócsi, István

    2015-07-01

    The application of yeasts has great potential in reducing the economic damage caused by toxigenic fungi in the agriculture. Some yeasts may act as biocontrol agents inhibiting the growth of filamentous fungi. These species may also gain importance in the preservation of agricultural products and in the reduction of their mycotoxin contamination, yet the extent of mycotoxin production in the presence of biocontrol agents is relatively less understood. The application of yeasts in various technological processes may have a direct inhibitory effect on the toxin production of certain molds, which is independent of their growth suppressing effect. Furthermore, several yeast species are capable of accumulating mycotoxins from agricultural products, thereby effectively decontaminating them. Probiotic yeasts or products containing yeast cell wall are also applied to counteract mycotoxicosis in livestock. Several yeast strains are also able to degrade toxins to less-toxic or even non-toxic substances. This intensively researched field would greatly benefit from a deeper knowledge on the genetic and molecular basis of toxin degradation. Moreover, yeasts and their biotechnologically important enzymes may exhibit sensitivity to certain mycotoxins, thereby mounting a considerable problem for the biotechnological industry. It is noted that yeasts are generally regarded as safe; however, there are reports of toxin degrading species that may cause human fungal infections. The aspects of yeast-mycotoxin relations with a brief consideration of strain improvement strategies and genetic modification for improved detoxifying properties and/or mycotoxin resistance are reviewed here.

  17. Yeasts colonizing the leaf surfaces.

    PubMed

    Sláviková, Elena; Vadkertiová, Renata; Vránová, Dana

    2007-08-01

    The yeasts were isolated from the leaf surfaces of ten species of trees. The study site was a forest park (Zelezná Studnicka) of the Small Carpathians mountain range. One hundred and thirty seven yeast strains belonging to 13 genera were isolated from 320 samples of leaves and needles. Seventeen yeast species were isolated, but only seven occurred regularly: Aureobasidium pullulans, Cryptococcus laurentii, Pichia anomala, Metschnikowia pulcherrima, Saccharomyces sp., Lachancea thermotolerans, and Rhodotorula glutinis. The remaining species were isolated from the leaves and needles of three or less tree species. A. pullulans, Cr. laurentii, and P. anomala were the most frequently found species and they occurred on leaves and needles of all ten tree species. Saccharomyces sp. occurred in leaf samples collected from eight kinds of trees. M. pulcherrima and L. thermotolerans were found in samples collected from six species of trees. Both these species occurred almost always on the leaves of deciduous trees. Rh. glutinis was the most frequently isolated carotenoids producing species. We have found out that the ascomycetous and basidiomycetous species were present in the leaf samples in approximately equal frequency, contrary to the soil samples taken from this forest park, where the ascomycetous species were found rarely.

  18. Yeasts Diversity in Fermented Foods and Beverages

    NASA Astrophysics Data System (ADS)

    Tamang, Jyoti Prakash; Fleet, Graham H.

    People across the world have learnt to culture and use the essential microorganisms for production of fermented foods and alcoholic beverages. A fermented food is produced either spontaneously or by adding mixed/pure starter culture(s). Yeasts are among the essential functional microorganisms encountered in many fermented foods, and are commercially used in production of baker's yeast, breads, wine, beer, cheese, etc. In Asia, moulds are predominant followed by amylolytic and alcohol-producing yeasts in the fermentation processes, whereas in Africa, Europe, Australia and America, fermented products are prepared exclusively using bacteria or bacteria-yeasts mixed cultures. This chapter would focus on the varieties of fermented foods and alcoholic beverages produced by yeasts, their microbiology and role in food fermentation, widely used commercial starters (pilot production, molecular aspects), production technology of some common commercial fermented foods and alcoholic beverages, toxicity and food safety using yeasts cultures and socio-economy

  19. [Metabolomics analysis of taxadiene producing yeasts].

    PubMed

    Yan, Huifang; Ding, Mingzhu; Yuan, Yingjin

    2014-02-01

    In order to study the inherent difference among terpenes producing yeasts from the point of metabolomics, we selected taxadiene producing yeasts as the model system. The changes of cellular metabolites during fermentation log phase of artificial functional yeasts were determined using metabolomics methods. The results represented that compared to W303-1A as a blank control, the metabolites in glycolysis, tricarboxylic acid cycle (TCA) cycle and several amino acids were influenced. And due to the changes of metabolites, the growth of cells was inhibited to a certain extent. Among the metabolites identified, citric acid content in taxadiene producing yeasts changed the most, the decreasing amplitude reached 90% or more. Therefore, citric acid can be a marker metabolite for the future study of artificial functional yeasts. The metabolomics analysis of taxadiene producing yeasts can provide more information in further studies on optimization of terpenes production in heterologous chassis.

  20. Tracer studies of nitrogen assimilation in yeast.

    PubMed

    ABRAMS, R; HAMMARSTEN, E

    1949-01-01

    By using N(15) as a tracer the assimilation of ammonia by the yeast, Torulopsis utilis, has been studied. It has been shown that: 1. There was no measurable incorporation of N in the protein or polynucleotide purine of carbon-starved yeast. 2. When ammonia is added to nitrogen-starved yeast there is a long lag period before division begins during which the yeast rapidly synthesizes protein, this process being accompanied by a turnover of polynucleotide purine. There was no significant dilution of the N(15)H(4) (+) of the medium by ordinary NH(4) (+). 3. When yeast containing N(15) is allowed to divide and grow in ordinary ammonia, the total amount of N(15) in the yeast remains constant. The dicarboxylic amino acids are most diluted, while arginine and nucleic acid guanine are not diluted at all.

  1. Manipulating yeast genome using plasmid vectors.

    PubMed

    Stearns, T; Ma, H; Botstein, D

    1990-01-01

    The vectors and techniques described here enable one to manipulate the yeast genome to meet specific needs. Genes can be cloned, and the clone used to delete the wild-type gene from the chromosome, or replace it with mutant versions. Mutants derived by classical methods, such as mutagenesis of whole cells, or by reversion of a phenotype, can be cloned and analyzed in vitro. Yeast genes and foreign genes can either be inserted into autonomously replicating plasmid vectors that are reasonably stable or integrated into a yeast chromosome where they are maintained at one copy per genome. The combination of these techniques with the characterized promoter systems available in yeast make it possible to express almost any gene in yeast. Once this is achieved, the entire repertoire of yeast genetics is available to probe the function of the gene, or to engineer the expression in useful ways.

  2. Beer brewing using a fusant between a sake yeast and a brewer's yeast.

    PubMed

    Mukai, N; Nishimori, C; Fujishige, I W; Mizuno, A; Takahashi, T; Sato, K

    2001-01-01

    Beer brewing using a fusant between a sake yeast (a lysine auxotrophic mutant of sake yeast K-14) and a brewer's yeast (a respiratory-deficient mutant of the top fermentation yeast NCYC1333) was performed to take advantage of the beneficial characteristics of sake yeasts, i.e., the high productivity of esters, high tolerance to ethanol, and high osmotolerance. The fusant (F-32) obtained was different from the parental yeasts regarding, for example, the assimilation of carbon sources and tolerance to ethanol. A brewing trial with the fusant was carried out using a 100-l pilot-scale plant. The fusant fermented wort more rapidly than the parental brewer's yeast. However, the sedimentation capacity of the fusant was relatively low. The beer brewed using the fusant contained more ethanol and esters compared to that brewed using the parental brewer's yeast. The fusant also obtained osmotolerance in the fermentation of maltose and fermented high-gravity wort well.

  3. Yeasts in floral nectar: a quantitative survey

    PubMed Central

    Herrera, Carlos M.; de Vega, Clara; Canto, Azucena; Pozo, María I.

    2009-01-01

    Background and Aims One peculiarity of floral nectar that remains relatively unexplored from an ecological perspective is its role as a natural habitat for micro-organisms. This study assesses the frequency of occurrence and abundance of yeast cells in floral nectar of insect-pollinated plants from three contrasting plant communities on two continents. Possible correlations between interspecific differences in yeast incidence and pollinator composition are also explored. Methods The study was conducted at three widely separated areas, two in the Iberian Peninsula (Spain) and one in the Yucatán Peninsula (Mexico). Floral nectar samples from 130 species (37–63 species per region) in 44 families were examined microscopically for the presence of yeast cells. For one of the Spanish sites, the relationship across species between incidence of yeasts in nectar and the proportion of flowers visited by each of five major pollinator categories was also investigated. Key Results Yeasts occurred regularly in the floral nectar of many species, where they sometimes reached extraordinary densities (up to 4 × 105 cells mm−3). Depending on the region, between 32 and 44 % of all nectar samples contained yeasts. Yeast cell densities in the order of 104 cells mm−3 were commonplace, and densities >105 cells mm−3 were not rare. About one-fifth of species at each site had mean yeast cell densities >104 cells mm−3. Across species, yeast frequency and abundance were directly correlated with the proportion of floral visits by bumble-bees, and inversely with the proportion of visits by solitary bees. Conclusions Incorporating nectar yeasts into the scenario of plant–pollinator interactions opens up a number of intriguing avenues for research. In addition, with yeasts being as ubiquitous and abundant in floral nectars as revealed by this study, and given their astounding metabolic versatility, studies focusing on nectar chemical features should carefully control for the presence

  4. Topical therapy for mucosal yeast infections.

    PubMed

    Summers, Paul R

    2011-01-01

    Mucosal yeast infection is best understood as a consequence of compromised mucosal cell-mediated and innate immunity. Defense against oral candidiasis is dominantly cell mediated. The innate immune system may play the main role in regulating vulvovaginal yeast infection. Conditions that compromise cell-mediated immunity such as leukemia, severe illness and HIV infection must be considered as predisposing factors for recurrent oral candidiasis. Compromise of vaginal innate immunity due to mucosal allergy or due to a genetic defect such as mannose-binding lectin deficiency contributes to chronic vulvovaginal yeast infection. Treatment of cofactors must be considered in order to achieve control in recurrent mucosal yeast infection.

  5. Yeast phytases: present scenario and future perspectives.

    PubMed

    Kaur, Parvinder; Kunze, G; Satyanarayana, T

    2007-01-01

    Phytases hydrolyze phytates to liberate soluble and thus readily utilizable inorganic phosphate. Although phytases are produced by various groups of microbes, yeasts being simple eukaryotes and mostly non-pathogenic with proven probiotic benefits can serve as ideal candidates for phytase research. The full potential of yeast phytases has not, however, been exploited. This review focuses attention on the present status of knowledge on the production, characterization, molecular characteristics, and cloning and over-expression of yeast phytases. Several potential applications of the yeast phytases in feeds and foods, and in the synthesis of lower myo-inositol phosphates are also discussed.

  6. Evaluation of Automated Yeast Identification System

    NASA Technical Reports Server (NTRS)

    McGinnis, M. R.

    1996-01-01

    One hundred and nine teleomorphic and anamorphic yeast isolates representing approximately 30 taxa were used to evaluate the accuracy of the Biolog yeast identification system. Isolates derived from nomenclatural types, environmental, and clinica isolates of known identity were tested in the Biolog system. Of the isolates tested, 81 were in the Biolog database. The system correctly identified 40, incorrectly identified 29, and was unable to identify 12. Of the 28 isolates not in the database, 18 were given names, whereas 10 were not. The Biolog yeast identification system is inadequate for the identification of yeasts originating from the environment during space program activities.

  7. YMDB: the Yeast Metabolome Database

    PubMed Central

    Jewison, Timothy; Knox, Craig; Neveu, Vanessa; Djoumbou, Yannick; Guo, An Chi; Lee, Jacqueline; Liu, Philip; Mandal, Rupasri; Krishnamurthy, Ram; Sinelnikov, Igor; Wilson, Michael; Wishart, David S.

    2012-01-01

    The Yeast Metabolome Database (YMDB, http://www.ymdb.ca) is a richly annotated ‘metabolomic’ database containing detailed information about the metabolome of Saccharomyces cerevisiae. Modeled closely after the Human Metabolome Database, the YMDB contains >2000 metabolites with links to 995 different genes/proteins, including enzymes and transporters. The information in YMDB has been gathered from hundreds of books, journal articles and electronic databases. In addition to its comprehensive literature-derived data, the YMDB also contains an extensive collection of experimental intracellular and extracellular metabolite concentration data compiled from detailed Mass Spectrometry (MS) and Nuclear Magnetic Resonance (NMR) metabolomic analyses performed in our lab. This is further supplemented with thousands of NMR and MS spectra collected on pure, reference yeast metabolites. Each metabolite entry in the YMDB contains an average of 80 separate data fields including comprehensive compound description, names and synonyms, structural information, physico-chemical data, reference NMR and MS spectra, intracellular/extracellular concentrations, growth conditions and substrates, pathway information, enzyme data, gene/protein sequence data, as well as numerous hyperlinks to images, references and other public databases. Extensive searching, relational querying and data browsing tools are also provided that support text, chemical structure, spectral, molecular weight and gene/protein sequence queries. Because of S. cervesiae's importance as a model organism for biologists and as a biofactory for industry, we believe this kind of database could have considerable appeal not only to metabolomics researchers, but also to yeast biologists, systems biologists, the industrial fermentation industry, as well as the beer, wine and spirit industry. PMID:22064855

  8. Spoilage yeasts in the wine industry.

    PubMed

    Loureiro, V; Malfeito-Ferreira, M

    2003-09-01

    Yeasts play a central role in the spoilage of foods and beverages, mainly those with high acidity and reduced water activity (a(w)). A few species are capable of spoiling foods produced according to good manufacturing practices (GMPs). These can survive and grow under stress conditions where other microorganisms are not competitive. However, many of the aspects determining yeast spoilage have yet to be clarified. This critical review uses the wine industry as a case study where serious microbiological problems are caused by yeasts. First, the limitations of the available tools to assess the presence of spoilage yeasts in foods are discussed. Next, yeasts and factors promoting their colonisation in grapes and wines are discussed from the ecological perspective, demonstrating that a deeper knowledge of vineyard and winery ecosystems is essential to establish the origin of wine spoilage yeasts, their routes of contamination, critical points of yeast infection, and of course, their control. Further, zymological indicators are discussed as important tools to assess the microbiological quality of wines, although they are rarely used by the wine industry. The concepts of the susceptibility of wine to spoilage yeasts and wine stability are addressed based on scientific knowledge and industrial practices for monitoring yeast contamination. A discussion on acceptable levels of yeasts and microbiological criteria in the wine industry is supported by data obtained from wineries, wholesalers, and the scientific literature.Finally, future directions for applied research are proposed, involving collaboration between scientists and industry to improve the quality of wine and methods for monitoring the presence of yeast.

  9. Surface Structure of Yeast Protoplasts

    PubMed Central

    Streiblová, Eva

    1968-01-01

    The fine structure of the yeast cell wall during protoplast formation was studied by means of phase-contrast microscopy and the freeze-etching technique. The freeze-etching results indicated that at least in some cases the entire wall substance was not removed from the surface of the protoplasts. After a treatment of 30 min to 3 hr with 2% snail enzymes, an innermost thin wall layer as well as remnants of the fibrillar middle layer sometimes could be demonstrated. Images PMID:4867751

  10. Experimental evolution in budding yeast

    NASA Astrophysics Data System (ADS)

    Murray, Andrew

    2012-02-01

    I will discuss our progress in analyzing evolution in the budding yeast, Saccharomyces cerevisiae. We take two basic approaches. The first is to try and examine quantitative aspects of evolution, for example by determining how the rate of evolution depends on the mutation rate and the population size or asking whether the rate of mutation is uniform throughout the genome. The second is to try to evolve qualitatively novel, cell biologically interesting phenotypes and track the mutations that are responsible for the phenotype. Our efforts include trying to alter cell morphology, evolve multicellularity, and produce a biological oscillator.

  11. Characterization of an encapsulation device for the production of monodisperse alginate beads for cell immobilization.

    PubMed

    Serp, D; Cantana, E; Heinzen, C; Von Stockar, U; Marison, I W

    2000-10-05

    An encapsulation device, designed on the basis of the laminar jet break-up technique, is characterized for cell immobilization with different types of alginate. The principle of operation of the completely sterilizable encapsulator, together with techniques for the continuous production of beads from 250 microm to 1 mm in diameter, with a size distribution below 5%, at a flow rate of 1-15 mL/min, is described. A modification of the device, to incorporate an electrostatic potential between the alginate droplets and an internal electrode, results in enhanced monodispersity with no adverse effects on cell viability. The maximum cell loading capacity of the beads strongly depends on the nozzle diameter as well as the cells used. For the yeast Phaffia rhodozyma, it is possible to generate 700 microm alginate beads with an initial cell concentration of 1 x 10(8) cells/mL of alginate whereas only 1 x 10(6) cells/ml could be entrapped within 400 microm beads. The alginate beads have been characterized with respect to mechanical resistance and size distribution immediately after production and as a function of storage conditions. The beads remain stable in the presence of acetic acid, hydrochloric acid, water, basic water, and sodium ions. The latter stability applies when the ratio of sodium: calcium ions is less than 1/5. Complexing agents such as sodium citrate result in the rapid solubilization of the beads due to calcium removal. The presence of cells does not affect the mechanical resistance of the beads. Finally, the mechanical resistance of alginate beads can be doubled by treatment with 5-10 kDa chitosan, resulting in reduced leaching of cells.

  12. Prevention of Yeast Spoilage in Feed and Food by the Yeast Mycocin HMK

    PubMed Central

    Lowes, K. F.; Shearman, C. A.; Payne, J.; MacKenzie, D.; Archer, D. B.; Merry, R. J.; Gasson, M. J.

    2000-01-01

    The yeast Williopsis mrakii produces a mycocin or yeast killer toxin designated HMK; this toxin exhibits high thermal stability, high pH stability, and a broad spectrum of activity against other yeasts. We describe construction of a synthetic gene for mycocin HMK and heterologous expression of this toxin in Aspergillus niger. Mycocin HMK was fused to a glucoamylase protein carrier, which resulted in secretion of biologically active mycocin into the culture media. A partial purification protocol was developed, and a comparison with native W. mrakii mycocin showed that the heterologously expressed mycocin had similar physiological properties and an almost identical spectrum of biological activity against a number of yeasts isolated from silage and yoghurt. Two food and feed production systems prone to yeast spoilage were used as models to assess the ability of mycocin HMK to act as a biocontrol agent. The onset of aerobic spoilage in mature maize silage was delayed by application of A. niger mycocin HMK on opening because the toxin inhibited growth of the indigenous spoilage yeasts. This helped maintain both higher lactic acid levels and a lower pH. In yoghurt spiked with dairy spoilage yeasts, A. niger mycocin HMK was active at all of the storage temperatures tested at which yeast growth occurred, and there was no resurgence of resistant yeasts. The higher the yeast growth rate, the more effective the killing action of the mycocin. Thus, mycocin HMK has potential applications in controlling both silage spoilage and yoghurt spoilage caused by yeasts. PMID:10698773

  13. Yeast: An Experimental Organism for Modern Biology.

    ERIC Educational Resources Information Center

    Botstein, David; Fink, Gerald R.

    1988-01-01

    Discusses the applicability and advantages of using yeasts as popular and ideal model systems for studying and understanding eukaryotic biology at the cellular and molecular levels. Cites experimental tractability and the cooperative tradition of the research community of yeast biologists as reasons for this success. (RT)

  14. Comparative genomics of biotechnologically important yeasts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ascomycete yeasts are metabolically diverse, with great potential for biotechnology. Here, we report the comparative genome analysis of 29 taxonomically and biotechnologically important yeasts, including 16 newly sequenced. We identify a genetic code change, CUG-Ala, in Pachysolen tannophilus in the...

  15. The wine and beer yeast Dekkera bruxellensis

    PubMed Central

    Schifferdecker, Anna Judith; Dashko, Sofia; Ishchuk, Olena P; Piškur, Jure

    2014-01-01

    Recently, the non-conventional yeast Dekkera bruxellensis has been gaining more and more attention in the food industry and academic research. This yeast species is a distant relative of Saccharomyces cerevisiae and is especially known for two important characteristics: on the one hand, it is considered to be one of the main spoilage organisms in the wine and bioethanol industry; on the other hand, it is 'indispensable' as a contributor to the flavour profile of Belgium lambic and gueuze beers. Additionally, it adds to the characteristic aromatic properties of some red wines. Recently this yeast has also become a model for the study of yeast evolution. In this review we focus on the recently developed molecular and genetic tools, such as complete genome sequencing and transformation, to study and manipulate this yeast. We also focus on the areas that are particularly well explored in this yeast, such as the synthesis of off-flavours, yeast detection methods, carbon metabolism and evolutionary history. © 2014 The Authors. Yeast published by John Wiley & Sons, Ltd. PMID:24932634

  16. Geographical differences in human oral yeast flora.

    PubMed

    Xu, Jianping; Mitchell, Thomas G

    2003-01-15

    The oral yeast flora of healthy humans from eastern North America and China were sampled and compared. Chinese persons harbored a greater number and diversity of yeast species in the mouth. Furthermore, Candida albicans, which is the predominant commensal and etiologic species of candidiasis in Europe and the Western Hemisphere, was relatively rare in China.

  17. Yeasts are essential for cocoa bean fermentation.

    PubMed

    Ho, Van Thi Thuy; Zhao, Jian; Fleet, Graham

    2014-03-17

    Cocoa beans (Theobroma cacao) are the major raw material for chocolate production and fermentation of the beans is essential for the development of chocolate flavor precursors. In this study, a novel approach was used to determine the role of yeasts in cocoa fermentation and their contribution to chocolate quality. Cocoa bean fermentations were conducted with the addition of 200ppm Natamycin to inhibit the growth of yeasts, and the resultant microbial ecology and metabolism, bean chemistry and chocolate quality were compared with those of normal (control) fermentations. The yeasts Hanseniaspora guilliermondii, Pichia kudriavzevii and Kluyveromyces marxianus, the lactic acid bacteria Lactobacillus plantarum and Lactobacillus fermentum and the acetic acid bacteria Acetobacter pasteurianus and Gluconobacter frateurii were the major species found in the control fermentation. In fermentations with the presence of Natamycin, the same bacterial species grew but yeast growth was inhibited. Physical and chemical analyses showed that beans fermented without yeasts had increased shell content, lower production of ethanol, higher alcohols and esters throughout fermentation and lesser presence of pyrazines in the roasted product. Quality tests revealed that beans fermented without yeasts were purplish-violet in color and not fully brown, and chocolate prepared from these beans tasted more acid and lacked characteristic chocolate flavor. Beans fermented with yeast growth were fully brown in color and gave chocolate with typical characters which were clearly preferred by sensory panels. Our findings demonstrate that yeast growth and activity were essential for cocoa bean fermentation and the development of chocolate characteristics.

  18. Fermentation studies using Saccharomyces diastaticus yeast strains

    SciTech Connect

    Erratt, J.A.; Stewart, G.G.

    1981-01-01

    The yeast species, Saccharomyces diastaticus, has the ability to ferment starch and dextrin, because of the extracellular enzyme, glucoamylase, which hydrolyzes the starch/dextrin to glucose. A number of nonallelic genes--DEX 1, DEX 2, and dextrinase B which is allelic to STA 3--have been isolated, which impart to the yeast the ability to ferment dextrin. Various diploid yeast strains were constructed, each being either heterozygous or homozygous for the individual dextrinase genes. Using 12 (sup 0) plato hopped wort (30% corn adjunct) under agitated conditions, the fermentation rates of the various diploid yeast strains were monitored. A gene-dosage effect was exhibited by yeast strains containing DEX 1 or DEX 2, however, not with yeast strains containing dextrinase B (STA 3). The fermentation and growth rates and extents were determined under static conditions at 14.4 C and 21 C. With all yeast strains containing the dextrinase genes, both fermentation and growth were increased at the higher incubation temperature. Using 30-liter fermentors, beer was produced with the various yeast strains containing the dextrinase genes and the physical and organoleptic characteristics of the products were determined. The concentration of glucose in the beer was found to increase during a 3-mo storage period at 21 C, indicating that the glucoamylase from Saccharomyces diastaticus is not inactivated by pasteurization. (Refs. 36).

  19. Comparative genomics of biotechnologically important yeasts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Saccharomyces cerevisiae, is used in the vast majority of the world’s bioprocesses, and its economic significance is unchallenged. It, however, represents only a small slice of yeast physiological diversity. Many other yeasts, are used in lesser known, but commercially important processes that take ...

  20. Growth requirements of san francisco sour dough yeasts and bakers' yeast.

    PubMed

    Henry, N

    1976-03-01

    The growth requirements of several yeasts isolated from San Francisco sour dough mother sponges were compared with those of bakers' yeast. The sour dough yeasts studied were one strain of Saccharomyces uvarum, one strain of S. inusitatus, and four strains of S. exiguus. S. inusitatus was the only yeast found to have an amino acid requirement, namely, methionine. All of the yeasts had an absolute requirement for pantothenic acid and a partial requirement for biotin. Inositol was stimulatory to all except bakers' yeast. All strains of S. exiguus required niacin and thiamine. Interestingly, S. inusitatus, the only yeast that required methionine, also needed folic acid. For optimal growth of S. exiguus in a molasses medium, supplementation with thiamine was required.

  1. Anhydrobiosis in yeast: influence of calcium and magnesium ions on yeast resistance to dehydration-rehydration.

    PubMed

    Trofimova, Yuliya; Walker, Graeme; Rapoport, Alexander

    2010-07-01

    The influence of calcium and magnesium ions on resistance to dehydration in the yeast, Saccharomyces cerevisiae, was investigated. Magnesium ion availability directly influenced yeast cells' resistance to dehydration and, when additionally supplemented with calcium ions, this provided further significant increase of yeast resistance to dehydration. Gradual rehydration of dry yeast cells in water vapour indicated that both magnesium and calcium may be important for the stabilization of yeast cell membranes. In particular, calcium ions were shown for the first time to increase the resistance of yeast cells to dehydration in stress-sensitive cultures from exponential growth phases. It is concluded that magnesium and calcium ion supplementations in nutrient media may increase the dehydration stress tolerance of S. cerevisiae cells significantly, and this finding is important for the production of active dry yeast preparations for food and fermentation industries.

  2. Genetic constitution of industrial yeast.

    PubMed

    Benítez, T; Martínez, P; Codón, A C

    1996-09-01

    Saccharomyces cerevisiae industrial yeast strains are highly heterogeneous. These industrial strains, including bakers', wine, brewing and distillers', have been compared with respect to their DNA content, number and size of chromosomes, homologies between their genes and those of laboratory strains, and restriction fragment lengths of their mitDNA. A high variability, and the presence of multigenic families, were observed in some industrial yeast groups. The occurrence or the lack of chromosomal polymorphism, as well as the presence of multiple copies of some genes, could be related to a selective process occurring under specific industrial conditions. This polymorphism is generated by reorganization events, that take place mainly during meiosis and are mediated by repetitive Y' and Ty elements. These elements give rise to ectopic and asymmetric recombination and to gene conversion. The polymorphism displayed by the mitDNA could also result from specific industrial conditions. However, in enological strains the selective process is masked by the mutagenic effect that ethanol exerts on this DNA.

  3. Antifungal resistance in yeast vaginitis.

    PubMed Central

    Dun, E.

    1999-01-01

    The increased number of vaginal yeast infections in the past few years has been a disturbing trend, and the scientific community has been searching for its etiology. Several theories have been put forth to explain the apparent increase. First, the recent widespread availability of low-dosage, azole-based over-the-counter antifungal medications for vaginal yeast infections encourages women to self-diagnose and treat, and women may be misdiagnosing themselves. Their vaginitis may be caused by bacteria, parasites or may be a symptom of another underlying health condition. As a result, they may be unnecessarily and chronically expose themselves to antifungal medications and encourage fungal resistance. Second, medical technology has increased the life span of seriously immune compromised individuals, yet these individuals are frequently plagued by opportunistic fungal infections. Long-term and intense azole-based antifungal treatment has been linked to an increase in resistant Candida and non-Candida species. Thus, the future of limiting antifungal resistance lies in identifying the factors promoting resistance and implementing policies to prevent it. PMID:10907778

  4. Regulation of yeast oscillatory dynamics

    PubMed Central

    Murray, Douglas B.; Beckmann, Manfred; Kitano, Hiroaki

    2007-01-01

    When yeast cells are grown continuously at high cell density, a respiratory oscillation percolates throughout the population. Many essential cellular functions have been shown to be separated temporally during each cycle; however, the regulatory mechanisms involved in oscillatory dynamics remain to be elucidated. Through GC-MS analysis we found that the majority of metabolites show oscillatory dynamics, with 70% of the identified metabolite concentrations peaking in conjunction with NAD(P)H. Through statistical analyses of microarray data, we identified that biosynthetic events have a defined order, and this program is initiated when respiration rates are increasing. We then combined metabolic, transcriptional data and statistical analyses of transcription factor activity, identified the top oscillatory parameters, and filtered a large-scale yeast interaction network according to these parameters. The analyses and controlled experimental perturbation provided evidence that a transcriptional complex formed part of the timing circuit for biosynthetic, reductive, and cell cycle programs in the cell. This circuitry does not act in isolation because both have strong translational, proteomic, and metabolic regulatory mechanisms. Our data lead us to conclude that the regulation of the respiratory oscillation revolves around coupled subgraphs containing large numbers of proteins and metabolites, with a potential to oscillate, and no definable hierarchy, i.e., heterarchical control. PMID:17284613

  5. Functional expression of chicken calmodulin in yeast.

    PubMed

    Ohya, Y; Anraku, Y

    1989-01-31

    The coding region of a chicken calmodulin cDNA was fused to a galactose-inducible GAL1 promoter, and an expression system was constructed in the yeast Saccharomyces cerevisiae. Expression of calmodulin was demonstrated by purifying the heterologously expressed protein and analyzing its biochemical properties. When the expression plasmid was introduced into a calmodulin gene (cmd1)-disrupted strain of yeast, the cells grew in galactose medium, showing that chicken calmodulin could complement the lesion of yeast calmodulin functionally. Repression of chicken calmodulin in the (cmd1)-disrupted strain caused cell cycle arrest with a G2/M nucleus, as observed previously with a conditional-lethal mutant of yeast calmodulin. These results suggest that the essential function of calmodulin for cell proliferation is conserved in cells ranging from yeast to vertebrate cells.

  6. Yeast community survey in the Tagus estuary.

    PubMed

    de Almeida, João M G C F

    2005-07-01

    The yeast community in the waters of the Tagus estuary, Portugal, was followed for over a year in order to assess its dynamics. Yeast occurrence and incidence were measured and this information was related to relevant environmental data. Yeast occurrence did not seem to depend upon tides, but river discharge had a dramatic impact both on the density and diversity of the community. The occurrence of some yeasts was partially correlated with faecal pollution indicators. Yeast isolates were characterized by microsatellite primed PCR (MSP-PCR) fingerprinting and rRNA gene sequencing. The principal species found were Candida catenulata, C. intermedia, C. parapsilosis, Clavispora lusitaniae, Debaryomyces hansenii, Pichia guilliermondii, Rhodotorula mucilaginosa and Rhodosporidium diobovatum. The incidence of these species was evaluated against the environmental context of the samples and the current knowledge about the substrates from which they are usually isolated.

  7. Yeasts that utilize lactose in sweet whey

    SciTech Connect

    Gholson, J.H.; Gough, R.H.

    1980-01-01

    Since processing costs are usually higher for whey than for other available food or feed nutrients, only about one-third of whey produced in the US is used by food and feed industries. As a result whey disposal costs are a problem. Further; when whey is disposed of through municipal sewerage systems, the lactose present is changed by bacteria to lactic acid which tends to act as a preservative and retards further oxidation of whey constituents. This article describes a method of utilizing lactose-fermenting yeasts to produce large quantities of yeast cells, single-cell protein. Kluveromyces fragilis was found to be the most effective yeast species and the yeast cells produced could be used as a natural food or feed additive. Results of this study determined that certain methods and yeast strains could reduce whey-related pollution and thus help reduce costs of whey disposal.

  8. Modeling competition between yeast strains

    NASA Astrophysics Data System (ADS)

    de Gee, Maarten; van Mourik, Hilda; de Visser, Arjan; Molenaar, Jaap

    2016-04-01

    We investigate toxin interference competition between S. cerevisiae colonies grown on a solid medium. In vivo experiments show that the outcome of this competition depends strongly on nutrient availability and cell densities. Here we present a new model for S. cerevisiae colonies, calculating the local height and composition of the colonies. The model simulates yeast colonies that show a good fit to experimental data. Simulations of colonies that start out with a homogeneous mixture of toxin producing and toxin sensitive cells can display remarkable pattern formation, depending on the initial ratio of the strains. Simulations in which the toxin producing and toxin sensitive species start at nearby positions clearly show that toxin production is advantageous.

  9. Analysis of Yeast Extracellular Vesicles.

    PubMed

    Rodrigues, Marcio L; Oliveira, Debora L; Vargas, Gabriele; Girard-Dias, Wendell; Franzen, Anderson J; Frasés, Susana; Miranda, Kildare; Nimrichter, Leonardo

    2016-01-01

    Extracellular vesicles (EV) are important carriers of biologically active components in a number of organisms, including fungal cells. Experimental characterization of fungal EVs suggested that these membranous compartments are likely involved in the regulation of several biological events. In fungal pathogens, these events include mechanisms of disease progression and/or control, suggesting potential targets for therapeutic intervention or disease prophylaxis. In this manuscript we describe methods that have been used in the last 10 years for the characterization of EVs produced by yeast forms of several fungal species. Experimental approaches detailed in this chapter include ultracentrifugation methods for EV fractionation, chromatographic approaches for analysis of EV lipids, microscopy techniques for analysis of both intracellular and extracellular vesicular compartments, interaction of EVs with host cells, and physical chemical analysis of EVs by dynamic light scattering.

  10. Rheologically interesting polysaccharides from yeasts

    NASA Technical Reports Server (NTRS)

    Petersen, G. R.; Nelson, G. A.; Cathey, C. A.; Fuller, G. G.

    1989-01-01

    We have examined the relationships between primary, secondary, and tertiary structures of polysaccharides exhibiting the rheological property of friction (drag) reduction in turbulent flows. We found an example of an exopolysaccharide from the yeast Cryptococcus laurentii that possessed high molecular weight but exhibited lower than expected drag reducing activity. Earlier correlations by Hoyt showing that beta 1 --> 3, beta 2 --> 4, and alpha 1 --> 3 linkages in polysaccharides favored drag reduction were expanded to include correlations to secondary structure. The effect of sidechains in a series of gellan gums was shown to be related to sidechain length and position. Disruption of secondary structure in drag reducing polysaccharides reduced drag reducing activity for some but not all exopolysaccharides. The polymer from C. laurentii was shown to be more stable than xanthan gum and other exopolysaccharides under the most vigorous of denaturing conditions. We also showed a direct relationship between extensional viscosity measurements and the drag reducing coefficient for four exopolysaccharides.

  11. Accelerating Yeast Prion Biology using Droplet Microfluidics

    NASA Astrophysics Data System (ADS)

    Ung, Lloyd; Rotem, Assaf; Jarosz, Daniel; Datta, Manoshi; Lindquist, Susan; Weitz, David

    2012-02-01

    Prions are infectious proteins in a misfolded form, that can induce normal proteins to take the misfolded state. Yeast prions are relevant, as a model of human prion diseases, and interesting from an evolutionary standpoint. Prions may also be a form of epigenetic inheritance, which allow yeast to adapt to stressful conditions at rates exceeding those of random mutations and propagate that adaptation to their offspring. Encapsulation of yeast in droplet microfluidic devices enables high-throughput measurements with single cell resolution, which would not be feasible using bulk methods. Millions of populations of yeast can be screened to obtain reliable measurements of prion induction and loss rates. The population dynamics of clonal yeast, when a fraction of the cells are prion expressing, can be elucidated. Furthermore, the mechanism by which certain strains of bacteria induce yeast to express prions in the wild can be deduced. Integrating the disparate fields of prion biology and droplet microfluidics reveals a more complete picture of how prions may be more than just diseases and play a functional role in yeast.

  12. 21 CFR 184.1983 - Bakers yeast extract.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Bakers yeast extract. 184.1983 Section 184.1983... GRAS § 184.1983 Bakers yeast extract. (a) Bakers yeast extract is the food ingredient resulting from concentration of the solubles of mechanically ruptured cells of a selected strain of yeast,...

  13. 21 CFR 184.1983 - Bakers yeast extract.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Bakers yeast extract. 184.1983 Section 184.1983... Listing of Specific Substances Affirmed as GRAS § 184.1983 Bakers yeast extract. (a) Bakers yeast extract... a selected strain of yeast, Saccharomyces cerevisiae. It may be concentrated or dried. (b)...

  14. 21 CFR 172.590 - Yeast-malt sprout extract.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Yeast-malt sprout extract. 172.590 Section 172.590... CONSUMPTION Flavoring Agents and Related Substances § 172.590 Yeast-malt sprout extract. Yeast-malt sprout... prescribed conditions: (a) The additive is produced by partial hydrolysis of yeast extract (derived...

  15. 21 CFR 172.590 - Yeast-malt sprout extract.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Yeast-malt sprout extract. 172.590 Section 172.590... Substances § 172.590 Yeast-malt sprout extract. Yeast-malt sprout extract, as described in this section, may... produced by partial hydrolysis of yeast extract (derived from Saccharomyces cereviseae,...

  16. 21 CFR 184.1983 - Bakers yeast extract.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Bakers yeast extract. 184.1983 Section 184.1983... Listing of Specific Substances Affirmed as GRAS § 184.1983 Bakers yeast extract. (a) Bakers yeast extract... a selected strain of yeast, Saccharomyces cerevisiae. It may be concentrated or dried. (b)...

  17. 21 CFR 172.325 - Bakers yeast protein.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Bakers yeast protein. 172.325 Section 172.325 Food... Special Dietary and Nutritional Additives § 172.325 Bakers yeast protein. Bakers yeast protein may be safely used in food in accordance with the following conditions: (a) Bakers yeast protein is...

  18. 21 CFR 172.325 - Bakers yeast protein.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Bakers yeast protein. 172.325 Section 172.325 Food... Special Dietary and Nutritional Additives § 172.325 Bakers yeast protein. Bakers yeast protein may be safely used in food in accordance with the following conditions: (a) Bakers yeast protein is...

  19. 21 CFR 184.1983 - Bakers yeast extract.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Bakers yeast extract. 184.1983 Section 184.1983... Listing of Specific Substances Affirmed as GRAS § 184.1983 Bakers yeast extract. (a) Bakers yeast extract... a selected strain of yeast, Saccharomyces cerevisiae. It may be concentrated or dried. (b)...

  20. 21 CFR 172.898 - Bakers yeast glycan.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Bakers yeast glycan. 172.898 Section 172.898 Food... Multipurpose Additives § 172.898 Bakers yeast glycan. Bakers yeast glycan may be safely used in food in accordance with the following conditions: (a) Bakers yeast glycan is the comminuted, washed, pasteurized,...

  1. 21 CFR 172.898 - Bakers yeast glycan.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Bakers yeast glycan. 172.898 Section 172.898 Food... Multipurpose Additives § 172.898 Bakers yeast glycan. Bakers yeast glycan may be safely used in food in accordance with the following conditions: (a) Bakers yeast glycan is the comminuted, washed, pasteurized,...

  2. 21 CFR 172.325 - Bakers yeast protein.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Bakers yeast protein. 172.325 Section 172.325 Food... Special Dietary and Nutritional Additives § 172.325 Bakers yeast protein. Bakers yeast protein may be safely used in food in accordance with the following conditions: (a) Bakers yeast protein is...

  3. 21 CFR 172.590 - Yeast-malt sprout extract.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Yeast-malt sprout extract. 172.590 Section 172.590... CONSUMPTION Flavoring Agents and Related Substances § 172.590 Yeast-malt sprout extract. Yeast-malt sprout... prescribed conditions: (a) The additive is produced by partial hydrolysis of yeast extract (derived...

  4. 21 CFR 172.325 - Bakers yeast protein.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Bakers yeast protein. 172.325 Section 172.325 Food... Special Dietary and Nutritional Additives § 172.325 Bakers yeast protein. Bakers yeast protein may be safely used in food in accordance with the following conditions: (a) Bakers yeast protein is...

  5. 21 CFR 184.1983 - Bakers yeast extract.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Bakers yeast extract. 184.1983 Section 184.1983... Listing of Specific Substances Affirmed as GRAS § 184.1983 Bakers yeast extract. (a) Bakers yeast extract... a selected strain of yeast, Saccharomyces cerevisiae. It may be concentrated or dried. (b)...

  6. 21 CFR 172.590 - Yeast-malt sprout extract.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Yeast-malt sprout extract. 172.590 Section 172.590... CONSUMPTION Flavoring Agents and Related Substances § 172.590 Yeast-malt sprout extract. Yeast-malt sprout... prescribed conditions: (a) The additive is produced by partial hydrolysis of yeast extract (derived...

  7. 21 CFR 172.898 - Bakers yeast glycan.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Bakers yeast glycan. 172.898 Section 172.898 Food... Multipurpose Additives § 172.898 Bakers yeast glycan. Bakers yeast glycan may be safely used in food in accordance with the following conditions: (a) Bakers yeast glycan is the comminuted, washed, pasteurized,...

  8. 21 CFR 172.898 - Bakers yeast glycan.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Bakers yeast glycan. 172.898 Section 172.898 Food... Multipurpose Additives § 172.898 Bakers yeast glycan. Bakers yeast glycan may be safely used in food in accordance with the following conditions: (a) Bakers yeast glycan is the comminuted, washed, pasteurized,...

  9. 21 CFR 172.590 - Yeast-malt sprout extract.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Yeast-malt sprout extract. 172.590 Section 172.590... CONSUMPTION Flavoring Agents and Related Substances § 172.590 Yeast-malt sprout extract. Yeast-malt sprout... prescribed conditions: (a) The additive is produced by partial hydrolysis of yeast extract (derived...

  10. Corning and Kroger turn whey to yeast

    SciTech Connect

    Not Available

    1981-11-16

    It is reported that Corning and Kroger intend to build a 35,000 sq. ft. plant in Winchester, Ky., that will turn whey into bakers' yeast. The plant will convert whey from Kroger's dairies into bakers' yeast, supplying about 60% of the yeast needed for nine Kroger bakeries. It will also produce syrups and whey protein concentrate for use in other food processing activities. In addition to making useful products, the project will convert the whey to glucose and galactose. The protein component of the whey will be concentrated and used in various foods and feeds.

  11. Efforts to make and apply humanized yeast

    PubMed Central

    Laurent, Jon M.; Young, Jonathan H.; Kachroo, Aashiq H.

    2016-01-01

    Despite a billion years of divergent evolution, the baker’s yeast Saccharomyces cerevisiae has long proven to be an invaluable model organism for studying human biology. Given its tractability and ease of genetic manipulation, along with extensive genetic conservation with humans, it is perhaps no surprise that researchers have been able to expand its utility by expressing human proteins in yeast, or by humanizing specific yeast amino acids, proteins or even entire pathways. These methods are increasingly being scaled in throughput, further enabling the detailed investigation of human biology and disease-specific variations of human genes in a simplified model organism. PMID:26462863

  12. Pseudoporphyria associated with consumption of brewers' yeast.

    PubMed Central

    Lim, C K; Rideout, J M; Peters, T J

    1984-01-01

    A case of pseudoporphyria associated with excessive consumption of brewers ' yeast was studied. Detailed analysis of the yeast tablets by high performance liquid chromatography showed the presence of dicarboxylic deuteroporphyrin , mesoporphyrin, and protoporphyrin; coproporphyrin I and III isomers; and uroporphyrin I and III isomers. The faecal porphyrin concentration of the patient taking yeast tablets was significantly increased, resembling the excretion pattern in variegate porphyria. Any patient showing an unusual porphyrin excretion pattern on high performance liquid chromatography should be investigated for a possible dietary cause. PMID:6426673

  13. Yeast and yeast-like diversity in the southernmost glacier of Europe (Calderone Glacier, Apennines, Italy).

    PubMed

    Branda, Eva; Turchetti, Benedetta; Diolaiuti, Guglielmina; Pecci, Massimo; Smiraglia, Claudio; Buzzini, Pietro

    2010-06-01

    The present study reports the characterization of psychrophilic yeast and yeast-like diversity in cold habitats (superficial and deep sediments, ice cores and meltwaters) of the Calderone Glacier (Italy), which is the southernmost glacier in Europe. After incubation at 4 and 20 degrees C, sediments contained about 10(2)-10(3) CFU of yeasts g(-1). The number of viable yeast cells in ice and meltwaters was several orders of magnitude lower. The concomitant presence of viable bacteria and filamentous fungi has also been observed. In all, 257 yeast strains were isolated and identified by 26S rRNA gene D1/D2 and internal transcribed spacers (1 and 2) sequencing as belonging to 28 ascomycetous and basidiomycetous species of 11 genera (Candida, Cystofilobasidium, Cryptococcus, Dioszegia, Erythrobasidium, Guehomyces, Mastigobasidium, Mrakia, Mrakiella, Rhodotorula and Sporobolomyces). Among them, the species Cryptococcus gastricus accounted for almost 40% of the total isolates. In addition, 12 strains were identified as belonging to the yeast-like species Aureobasidium pullulans and Exophiala dermatitidis, whereas 15 strains, presumably belonging to new species, yet to be described, were also isolated. Results herein reported indicate that the Calderone Glacier, although currently considered a vanishing ice body due to the ongoing global-warming phenomenon, still harbors viable psychrophilic yeast populations. Differences of yeast and yeast-like diversity between the glacier under study and other worldwide cold habitats are also discussed.

  14. Yeast Infections: MedlinePlus Health Topic

    MedlinePlus

    ... Candidiasis ("Thrush") (Centers for Disease Control and Prevention) Tinea Versicolor (American Academy of Dermatology) Vaginal Yeast Infections (Department of Health and Human Services, Office on Women's Health) Also in Spanish ...

  15. [Red yeast rice: An unsafe food supplement?

    PubMed

    Steffen, Christian

    2017-03-01

    Red yeast rice is the fermentation product of the mould Monascus ruber and is traditionally used in East Asia to dye and conserve food. Its main pharmacologically active compound, monakolin K, was isolated from red yeast rice and is used as an inhibitor of cholesterol synthesis under the INN lovastatin. Lovastatin and several other statins are marketed as drugs whereas red yeast rice is offered as a food supplement. As statins can cause severe side effects, such as muscle damage and kidney failure, the dosing and information about interactions with drugs and food is essential for the use of these products. Furthermore, red yeast rice can contain the mycotoxin citrinin and several other substances that are not yet toxicologically evaluated.

  16. Barcode technology in yeast: application to pharmacogenomics.

    PubMed

    Delneri, Daniela

    2010-12-01

    The common baker's yeast, Saccharomyces cerevisiae, is one of the oldest domesticated organisms known, and has been exploited by our ancestors in several different applications, particularly in food and fermentations industries and in bioconversion and biodegradation processes. Over the years, yeast has become an excellent experimental model for biological and medical studies, thanks to its genetic tractability, well-known physiology and fast-doubling cycle. In the last decade, the advances in genome sequencing opened the doors to high-throughput studies and yeast quickly has become a model system for drug discovery and mode of action. This review provides a focused overview of the achievements in the field of human medicine and pharmacology by exploiting the molecular tools available for yeast.

  17. Developmentally programmed nuclear destruction during yeast gametogenesis.

    PubMed

    Eastwood, Michael D; Cheung, Sally W T; Lee, Kwan Yin; Moffat, Jason; Meneghini, Marc D

    2012-07-17

    Autophagy controls cellular catabolism in diverse eukaryotes and modulates programmed cell death in plants and animals. While studies of the unicellular yeast Saccharomyces cerevisiae have provided fundamental insights into the mechanisms of autophagy, the roles of cell death pathways in yeast are less well understood. Here, we describe widespread developmentally programmed nuclear destruction (PND) events that occur during yeast gametogenesis. PND is executed through apoptotic-like DNA fragmentation in coordination with an unusual form of autophagy that is most similar to mammalian lysosomal membrane permeabilization and mega-autophagy, a form of plant autophagic cell death. Undomesticated strains execute gametogenic PND broadly in maturing colonies to the apparent benefit of sibling cells, confirming its prominence during the yeast life cycle. Our results reveal that diverse cell-death-related processes converge during gametogenesis in a microbe distantly related to plants or animals, highlighting gametogenesis as a process during which programmed cell death mechanisms may have evolved.

  18. Genomic Evolution of the Ascomycete Yeasts

    SciTech Connect

    Riley, Robert; Haridas, Sajeet; Salamov, Asaf; Boundy-Mills, Kyria; Goker, Markus; Hittinger, Chris; Klenk, Hans-Peter; Lopes, Mariana; Meir-Kolthoff, Jan P.; Rokas, Antonis; Rosa, Carlos; Scheuner, Carmen; Soares, Marco; Stielow, Benjamin; Wisecaver, Jennifer H.; Wolfe, Ken; Blackwell, Meredith; Kurtzman, Cletus; Grigoriev, Igor; Jeffries, Thomas

    2015-03-16

    Yeasts are important for industrial and biotechnological processes and show remarkable metabolic and phylogenetic diversity despite morphological similarities. We have sequenced the genomes of 16 ascomycete yeasts of taxonomic and industrial importance including members of Saccharomycotina and Taphrinomycotina. Phylogenetic analysis of these and previously published yeast genomes helped resolve the placement of species including Saitoella complicata, Babjeviella inositovora, Hyphopichia burtonii, and Metschnikowia bicuspidata. Moreover, we find that alternative nuclear codon usage, where CUG encodes serine instead of leucine, are monophyletic within the Saccharomycotina. Most of the yeasts have compact genomes with a large fraction of single exon genes, and a tendency towards more introns in early-diverging species. Analysis of enzyme phylogeny gives insights into the evolution of metabolic capabilities such as methanol utilization and assimilation of alternative carbon sources.

  19. Monitoring Air Quality with Leaf Yeasts.

    ERIC Educational Resources Information Center

    Richardson, D. H. S.; And Others

    1985-01-01

    Proposes that leaf yeast serve as quick, inexpensive, and effective techniques for monitoring air quality. Outlines procedures and provides suggestions for data analysis. Includes results from sample school groups who employed this technique. (ML)

  20. DISRUPTION OF YEAST MEMBRANES BY METHYLPHENIDATE.

    DTIC Science & Technology

    Methylphenidate blocked sorbose uptake and loss by yeast spheroplasts and, at higher concentrations, disrupted spheroplasts. At high concentrations methylphenidate also ruptured the membranes of whole yeast cells; sorbose and 280 nm-absorbing materials were lost from the cells, and methylene blue stained them. Intracellular structures were extensively affected as shown by electron micrographs, and evidently were more sensitive to methylphenidate than the external membrane. N-ethylmaleimide and Ca(++) enhanced the rupture of external membranes by methylphenidate. (Author)

  1. Metallothionein function and genetic regulation in yeast

    SciTech Connect

    Ecker, D.J.; Butt, T.R.; Crooke, S.T.

    1986-05-01

    Copper resistance in yeast is mediated by the CUP1 locus which codes for yeast metallothionein (MT). A genetic approach was taken to study yeast MT gene regulation and to test the function of MT in the detoxification of metal ions other than copper. A yeast strain was constructed (cup1/sup ..delta../) in which the MT structural and regulatory sequences were deleted. The deleted gene was then replaced with the following genetically modified forms of MT on high copy episomal plasmid (YE/sup p/ 13): 1) the intact yeast gene with normal structural and regulatory sequences; 2) a constitutively expressed yeast promoter (TDH) running the yeast MT structural gene. Metal resistance in the cup1/sup ..delta../ strain and the cup1/sup ..delta../ strain transformed with the MT plasmid constructions was compared on metal-supplemented agar plates. Both of the high copy MT plasmids conferred in excess of 500-fold greater copper resistance to the cup1/sup ..delta../ strain. Increased cadmium resistance was not observed in any of the strains that had MT under normal regulatory control. However, the strain with constitutively expressed MT was in excess of 1000-fold more resistant to cadmium. Neither of the MT constructions conferred resistance to Hg,Zn,Co,Ni,Ag,Au,Pt,La,U or Sn. MT gene induction measured by the analysis of MT mRNA on northern blots showed that the yeast MT promoter is not induced by Cd, Zn, Au, Hg, Ag, superoxide, hydrogen peroxide, steroid hormones or heat shock.

  2. Subcellular localization of the yeast proteome.

    PubMed

    Kumar, Anuj; Agarwal, Seema; Heyman, John A; Matson, Sandra; Heidtman, Matthew; Piccirillo, Stacy; Umansky, Lara; Drawid, Amar; Jansen, Ronald; Liu, Yang; Cheung, Kei-Hoi; Miller, Perry; Gerstein, Mark; Roeder, G Shirleen; Snyder, Michael

    2002-03-15

    Protein localization data are a valuable information resource helpful in elucidating eukaryotic protein function. Here, we report the first proteome-scale analysis of protein localization within any eukaryote. Using directed topoisomerase I-mediated cloning strategies and genome-wide transposon mutagenesis, we have epitope-tagged 60% of the Saccharomyces cerevisiae proteome. By high-throughput immunolocalization of tagged gene products, we have determined the subcellular localization of 2744 yeast proteins. Extrapolating these data through a computational algorithm employing Bayesian formalism, we define the yeast localizome (the subcellular distribution of all 6100 yeast proteins). We estimate the yeast proteome to encompass approximately 5100 soluble proteins and >1000 transmembrane proteins. Our results indicate that 47% of yeast proteins are cytoplasmic, 13% mitochondrial, 13% exocytic (including proteins of the endoplasmic reticulum and secretory vesicles), and 27% nuclear/nucleolar. A subset of nuclear proteins was further analyzed by immunolocalization using surface-spread preparations of meiotic chromosomes. Of these proteins, 38% were found associated with chromosomal DNA. As determined from phenotypic analyses of nuclear proteins, 34% are essential for spore viability--a percentage nearly twice as great as that observed for the proteome as a whole. In total, this study presents experimentally derived localization data for 955 proteins of previously unknown function: nearly half of all functionally uncharacterized proteins in yeast. To facilitate access to these data, we provide a searchable database featuring 2900 fluorescent micrographs at http://ygac.med.yale.edu.

  3. Subcellular localization of the yeast proteome

    PubMed Central

    Kumar, Anuj; Agarwal, Seema; Heyman, John A.; Matson, Sandra; Heidtman, Matthew; Piccirillo, Stacy; Umansky, Lara; Drawid, Amar; Jansen, Ronald; Liu, Yang; Cheung, Kei-Hoi; Miller, Perry; Gerstein, Mark; Roeder, G. Shirleen; Snyder, Michael

    2002-01-01

    Protein localization data are a valuable information resource helpful in elucidating eukaryotic protein function. Here, we report the first proteome-scale analysis of protein localization within any eukaryote. Using directed topoisomerase I-mediated cloning strategies and genome-wide transposon mutagenesis, we have epitope-tagged 60% of the Saccharomyces cerevisiae proteome. By high-throughput immunolocalization of tagged gene products, we have determined the subcellular localization of 2744 yeast proteins. Extrapolating these data through a computational algorithm employing Bayesian formalism, we define the yeast localizome (the subcellular distribution of all 6100 yeast proteins). We estimate the yeast proteome to encompass ∼5100 soluble proteins and >1000 transmembrane proteins. Our results indicate that 47% of yeast proteins are cytoplasmic, 13% mitochondrial, 13% exocytic (including proteins of the endoplasmic reticulum and secretory vesicles), and 27% nuclear/nucleolar. A subset of nuclear proteins was further analyzed by immunolocalization using surface-spread preparations of meiotic chromosomes. Of these proteins, 38% were found associated with chromosomal DNA. As determined from phenotypic analyses of nuclear proteins, 34% are essential for spore viability—a percentage nearly twice as great as that observed for the proteome as a whole. In total, this study presents experimentally derived localization data for 955 proteins of previously unknown function: nearly half of all functionally uncharacterized proteins in yeast. To facilitate access to these data, we provide a searchable database featuring 2900 fluorescent micrographs at http://ygac.med.yale.edu. PMID:11914276

  4. Flor Yeast: New Perspectives Beyond Wine Aging.

    PubMed

    Legras, Jean-Luc; Moreno-Garcia, Jaime; Zara, Severino; Zara, Giacomo; Garcia-Martinez, Teresa; Mauricio, Juan C; Mannazzu, Ilaria; Coi, Anna L; Bou Zeidan, Marc; Dequin, Sylvie; Moreno, Juan; Budroni, Marilena

    2016-01-01

    The most important dogma in white-wine production is the preservation of the wine aroma and the limitation of the oxidative action of oxygen. In contrast, the aging of Sherry and Sherry-like wines is an aerobic process that depends on the oxidative activity of flor strains of Saccharomyces cerevisiae. Under depletion of nitrogen and fermentable carbon sources, these yeast produce aggregates of floating cells and form an air-liquid biofilm on the wine surface, which is also known as velum or flor. This behavior is due to genetic and metabolic peculiarities that differentiate flor yeast from other wine yeast. This review will focus first on the most updated data obtained through the analysis of flor yeast with -omic tools. Comparative genomics, proteomics, and metabolomics of flor and wine yeast strains are shedding new light on several features of these special yeast, and in particular, they have revealed the extent of proteome remodeling imposed by the biofilm life-style. Finally, new insights in terms of promotion and inhibition of biofilm formation through small molecules, amino acids, and di/tri-peptides, and novel possibilities for the exploitation of biofilm immobilization within a fungal hyphae framework, will be discussed.

  5. The growth of solar radiated yeast

    NASA Technical Reports Server (NTRS)

    Kraft, Tyrone

    1995-01-01

    This researcher plans to determine if solar radiation affects the growth of yeast. The irradiated yeast was obtained from a sample exposed in space during a Space Shuttle flight of September 9-20, 1994. Further, the control groups were held at: (1) Goddard Space Flight Center (GSFC) in Greenbelt, Maryland; and (2) South Dakota School of Mines and Technology. The procedure used was based on the fact that yeast is most often used in consumable baked goods. Therefore, the yeast was incorporated into a basic Betty Crocker bread recipe. Data was collected by placing measured amounts of dough into sample containers with fifteen minute growth in height measurements collected and recorded. This researcher assumed the viability of yeast to be relative to its ability to produce carbon dioxide gas and cause the dough to rise. As all ingredients and surroundings were equal, this researcher assumed the yeast will produce the only significant difference in data collected. This researcher noted the approximate use date on all sample packages to be prior to arrival and experiment date. All dates equal, it was then assumed each would act in a similar manner of response. This assumption will allow for equally correct data collection.

  6. Novel brewing yeast hybrids: creation and application.

    PubMed

    Krogerus, Kristoffer; Magalhães, Frederico; Vidgren, Virve; Gibson, Brian

    2017-01-01

    The natural interspecies Saccharomyces cerevisiae × Saccharomyces eubayanus hybrid yeast is responsible for global lager beer production and is one of the most important industrial microorganisms. Its success in the lager brewing environment is due to a combination of traits not commonly found in pure yeast species, principally low-temperature tolerance, and maltotriose utilization. Parental transgression is typical of hybrid organisms and has been exploited previously for, e.g., the production of wine yeast with beneficial properties. The parental strain S. eubayanus has only been discovered recently and newly created lager yeast strains have not yet been applied industrially. A number of reports attest to the feasibility of this approach and artificially created hybrids are likely to have a significant impact on the future of lager brewing. De novo S. cerevisiae × S. eubayanus hybrids outperform their parent strains in a number of respects, including, but not restricted to, fermentation rate, sugar utilization, stress tolerance, and aroma formation. Hybrid genome function and stability, as well as different techniques for generating hybrids and their relative merits are discussed. Hybridization not only offers the possibility of generating novel non-GM brewing yeast strains with unique properties, but is expected to aid in unraveling the complex evolutionary history of industrial lager yeast.

  7. Physiological and environmental control of yeast prions

    PubMed Central

    Chernova, Tatiana A.; Wilkinson, Keith D.; Chernoff, Yury O.

    2014-01-01

    Prions are self-perpetuating protein isoforms that cause fatal and incurable neurodegenerative disease in mammals. Recent evidence indicates that a majority of human proteins involved in amyloid and neural inclusion disorders possess at least some prion properties. In lower eukaryotes, such as yeast, prions act as epigenetic elements, which increase phenotypic diversity by altering a range of cellular processes. While some yeast prions are clearly pathogenic, it is also postulated that prion formation could be beneficial in variable environmental conditions. Yeast and mammalian prions have similar molecular properties. Crucial cellular factors and conditions influencing prion formation and propagation were uncovered in the yeast models. Stress-related chaperones, protein quality control deposits, degradation pathways and cytoskeletal networks control prion formation and propagation in yeast. Environmental stresses trigger prion formation and loss, supposedly acting via influencing intracellular concentrations of the prion-inducing proteins, and/or by localizing prionogenic proteins to the prion induction sites via heterologous ancillary helpers. Physiological and environmental modulation of yeast prions points to new opportunities for pharmacological intervention and/or prophylactic measures targeting general cellular systems rather than the properties of individual amyloids and prions. PMID:24236638

  8. The growth of solar radiated yeast

    SciTech Connect

    Kraft, T.

    1995-09-01

    This researcher plans to determine if solar radiation affects the growth of yeast. The irradiated yeast was obtained from a sample exposed in space during a Space Shuttle flight of September 9-20, 1994. Further, the control groups were held at: (1) Goddard Space Flight Center (GSFC) in Greenbelt, Maryland; and (2) South Dakota School of Mines and Technology. The procedure used was based on the fact that yeast is most often used in consumable baked goods. Therefore, the yeast was incorporated into a basic Betty Crocker bread recipe. Data was collected by placing measured amounts of dough into sample containers with fifteen minute growth in height measurements collected and recorded. This researcher assumed the viability of yeast to be relative to its ability to produce carbon dioxide gas and cause the dough to rise. As all ingredients and surroundings were equal, this researcher assumed the yeast will produce the only significant difference in data collected. This researcher noted the approximate use date on all sample packages to be prior to arrival and experiment date. All dates equal, it was then assumed each would act in a similar manner of response. This assumption will allow for equally correct data collection.

  9. Yeast communities in a natural tequila fermentation.

    PubMed

    Lachance, M A

    1995-08-01

    Fresh and cooked agave, Drosophila spp., processing equipment, agave molasses, agave extract, and fermenting must at a traditional tequila distillery (Herradura, Amatitan, Jalisco, México) were studied to gain insight on the origin of yeasts involved in a natural tequila fermentations. Five yeast communities were identified. (1) Fresh agave contained a diverse mycobiota dominated by Clavispora lusitaniae and an endemic species, Metschnikowia agaveae. (2) Drosophila spp. from around or inside the distillery yielded typical fruit yeasts, in particular Hanseniaspora spp., Pichia kluyveri, and Candida krusei. (3) Schizosaccharomyces pombe prevailed in molasses. (4) Cooked agave and extract had a considerable diversity of species, but included Saccharomyces cerevisiae. (5) Fermenting juice underwent a gradual reduction in yeast heterogeneity. Torulaspora delbrueckii, Kluyveromyces marxianus, and Hanseniaspora spp. progressively ceded the way to S. cerevisiae, Zygosaccharomyces bailii, Candida milleri, and Brettanomyces spp. With the exception of Pichia membranaefaciens, which was shared by all communities, little overlap existed. That separation was even more manifest when species were divided into distinguishable biotypes based on morphology or physiology. It is concluded that crushing equipment and must holding tanks are the main source of significant inoculum for the fermentation process. Drosophila species appear to serve as internal vectors. Proximity to fruit trees probably contributes to maintaining a substantial Drosophila community, but the yeasts found in the distillery exhibit very little similarity to those found in adjacent vegetation. Interactions involving killer toxins had no apparent direct effects on the yeast community structure.

  10. Phylogenetics of Saccharomycetales, the ascomycete yeasts.

    PubMed

    Suh, Sung-Oui; Blackwell, Meredith; Kurtzman, Cletus P; Lachance, Marc-André

    2006-01-01

    Ascomycete yeasts (phylum Ascomycota: subphylum Saccharomycotina: class Saccharomycetes: order Saccharomycetales) comprise a monophyletic lineage with a single order of about 1000 known species. These yeasts live as saprobes, often in association with plants, animals and their interfaces. A few species account for most human mycotic infections, and fewer than 10 species are plant pathogens. Yeasts are responsible for important industrial and biotechnological processes, including baking, brewing and synthesis of recombinant proteins. Species such as Saccharomyces cerevisiae are model organisms in research, some of which led to a Nobel Prize. Yeasts usually reproduce asexually by budding, and their sexual states are not enclosed in a fruiting body. The group also is well defined by synapomorphies visible at the ultrastructural level. Yeast identification and classification changed dramatically with the availability of DNA sequencing. Species identification now benefits from a constantly updated sequence database and no longer relies on ambiguous growth tests. A phylogeny based on single gene analyses has shown the order to be remarkably divergent despite morphological similarities among members. The limits of many previously described genera are not supported by sequence comparisons, and multigene phylogenetic studies are under way to provide a stable circumscription of genera, families and orders. One recent multigene study has resolved species of the Saccharomycetaceae into genera that differ markedly from those defined by analysis of morphology and growth responses, and similar changes are likely to occur in other branches of the yeast tree as additional sequences become available.

  11. Flor Yeast: New Perspectives Beyond Wine Aging

    PubMed Central

    Legras, Jean-Luc; Moreno-Garcia, Jaime; Zara, Severino; Zara, Giacomo; Garcia-Martinez, Teresa; Mauricio, Juan C.; Mannazzu, Ilaria; Coi, Anna L.; Bou Zeidan, Marc; Dequin, Sylvie; Moreno, Juan; Budroni, Marilena

    2016-01-01

    The most important dogma in white-wine production is the preservation of the wine aroma and the limitation of the oxidative action of oxygen. In contrast, the aging of Sherry and Sherry-like wines is an aerobic process that depends on the oxidative activity of flor strains of Saccharomyces cerevisiae. Under depletion of nitrogen and fermentable carbon sources, these yeast produce aggregates of floating cells and form an air–liquid biofilm on the wine surface, which is also known as velum or flor. This behavior is due to genetic and metabolic peculiarities that differentiate flor yeast from other wine yeast. This review will focus first on the most updated data obtained through the analysis of flor yeast with -omic tools. Comparative genomics, proteomics, and metabolomics of flor and wine yeast strains are shedding new light on several features of these special yeast, and in particular, they have revealed the extent of proteome remodeling imposed by the biofilm life-style. Finally, new insights in terms of promotion and inhibition of biofilm formation through small molecules, amino acids, and di/tri-peptides, and novel possibilities for the exploitation of biofilm immobilization within a fungal hyphae framework, will be discussed. PMID:27148192

  12. Training of yeast cell dynamics.

    PubMed

    Reijenga, Karin A; Bakker, Barbara M; van der Weijden, Coen C; Westerhoff, Hans V

    2005-04-01

    In both industrial fermenters and in their natural habitats, microorganisms often experience an inhomogeneous and fluctuating environment. In this paper we mimicked one aspect of this nonideal behaviour by imposing a low and oscillating extracellular glucose concentration on nonoscillating suspensions of yeast cells. The extracellular dynamics changed the intracellular dynamics--which was monitored through NADH fluorescence--from steady to equally dynamic; the latter followed the extracellular dynamics at the frequency of glucose pulsing. Interestingly, the amplitude of the oscillation of the NADH fluorescence increased with time. This increase in amplitude was sensitive to inhibition of protein synthesis, and was due to a change in the cells rather than in the medium; the cell population was 'trained' to respond to the extracellular dynamics. To examine the mechanism behind this 'training', we subjected the cells to a low and constant extracellular glucose concentration. Seventy-five minutes of adaptation to a low and constant glucose concentration induced the same increase of the amplitude of the forced NADH oscillations as did the train of glucose pulses. Furthermore, 75 min of adaptation to a low (oscillating or continuous) glucose concentration decreased the K(M) of the glucose transporter from 26 mm to 3.5 mm. When subsequently the apparent K(M) was increased by addition of maltose, the amplitude of the forced oscillations dropped to its original value. This demonstrated that the increased affinity of glucose transport was essential for the training of the cells' dynamics.

  13. Spermidine cures yeast of prions

    PubMed Central

    Speldewinde, Shaun H.; Grant, Chris M.

    2015-01-01

    Prions are self-perpetuating amyloid protein aggregates which underlie various neurodegenerative diseases in mammals. The molecular basis underlying their conversion from a normally soluble protein into the prion form remains largely unknown. Studies aimed at uncovering these mechanism(s) are therefore essential if we are to develop effective therapeutic strategies to counteract these disease-causing entities. Autophagy is a cellular degradation system which has predominantly been considered as a non-selective bulk degradation process which recycles macromolecules in response to starvation conditions. We now know that autophagy also serves as a protein quality control mechanism which selectively degrades protein aggregates and damaged organelles. These are commonly accumulated in various neurodegenerative disorders including prion diseases. In our recent study [Speldewinde et al. Mol. Biol. Cell. (2015)] we used the well-established yeast [PSI+]/Sup35 and [PIN¬+]/Rnq1 prion models to show that autophagy prevents sporadic prion formation. Importantly, we found that spermidine, a polyamine that has been used to increase autophagic flux, acts as a protective agent which prevents spontaneous prion formation.

  14. YeastIP: a database for identification and phylogeny of Saccharomycotina yeasts.

    PubMed

    Weiss, Stéphanie; Samson, Franck; Navarro, David; Casaregola, Serge

    2013-02-01

    With the advances in sequencing techniques, identification of ascomycetous yeasts to the species level and phylogeny reconstruction increasingly require curated and updated taxonomic information. A specific database with nucleotide sequences of the most common markers used for yeast taxonomy and phylogeny and a user-friendly interface allowing identification, taxonomy and phylogeny of yeasts species was developed. By 1 September 2012, the YeastIP database contained all the described Saccharomycotina species for which sequences used for taxonomy and phylogeny, such as D1/D2 rDNA and ITS, are available. The database interface was developed to provide a maximum of relevant information and data mining tools, including the following features: (1) the blast n program for the sequences of the YeastIP database; (2) easy retrieval of selected sequences; (3) display of the available markers for each selected group of species; and (4) a tool to concatenate marker sequences, including those provided by the user. The concatenation tool allows phylogeny reconstruction through a direct link to the Phylogeny.fr platform. YeastIP is thus a unique database in that it provides taxonomic information and guides users in their taxonomic analyses. YeastIP facilitates multigenic analysis to encourage good practice in ascomycetous yeast phylogeny (URL: http://genome.jouy.inra.fr/yeastip.).

  15. Antimycotic activity of 4-thioisosteres of flavonoids towards yeast and yeast-like microorganisms.

    PubMed

    Buzzini, Pietro; Menichetti, Stefano; Pagliuca, Chiara; Viglianisi, Caterina; Branda, Eva; Turchetti, Benedetta

    2008-07-01

    Different substituted methoxy- and hydroxy-4-thioisosteres of flavonoids were prepared and their in vitro antimycotic activity towards yeast (Candida spp., Clavispora spp., Cryptococcus spp., Filobasidiella spp., Issatchenkia spp., Pichia spp., Kluyveromyces spp., Saccharomyces spp. and Yarrowia spp.) and yeast-like (Prototheca spp.) microorganisms was tested. Further insights in the biological activities of these antioxidant, oestrogenic and antimicrobial biomimetic derivatives were obtained.

  16. Boolean Model of Yeast Apoptosis as a Tool to Study Yeast and Human Apoptotic Regulations

    PubMed Central

    Kazemzadeh, Laleh; Cvijovic, Marija; Petranovic, Dina

    2012-01-01

    Programmed cell death (PCD) is an essential cellular mechanism that is evolutionary conserved, mediated through various pathways and acts by integrating different stimuli. Many diseases such as neurodegenerative diseases and cancers are found to be caused by, or associated with, regulations in the cell death pathways. Yeast Saccharomyces cerevisiae, is a unicellular eukaryotic organism that shares with human cells components and pathways of the PCD and is therefore used as a model organism. Boolean modeling is becoming promising approach to capture qualitative behavior and describe essential properties of such complex networks. Here we present large literature-based and to our knowledge first Boolean model that combines pathways leading to apoptosis (a type of PCD) in yeast. Analysis of the yeast model confirmed experimental findings of anti-apoptotic role of Bir1p and pro-apoptotic role of Stm1p and revealed activation of the stress protein kinase Hog proposing the maximal level of activation upon heat stress. In addition we extended the yeast model and created an in silico humanized yeast in which human pro- and anti-apoptotic regulators Bcl-2 family and Valosin-contain protein (VCP) are included in the model. We showed that accumulation of Bax in silico humanized yeast shows apoptotic markers and that VCP is essential target of Akt Signaling. The presented Boolean model provides comprehensive description of yeast apoptosis network behavior. Extended model of humanized yeast gives new insights of how complex human disease like neurodegeneration can initially be tested. PMID:23233838

  17. Seborrhoeic dermatitis and Pityrosporum yeasts.

    PubMed

    Bergbrant, I M

    1995-01-01

    The connection between P. ovale and seborrhoeic dermatitis has been clearly demonstrated in a number of treatment studies but we still do not know how P. ovale induces skin lesions. An enhanced growth of P. ovale cannot be the cause, because a number of studies with quantitative determinations of P. ovale have not been able to show any difference in the number of yeast cells between patients and healthy controls. The number of P. ovale is probably only important for the individuals who are susceptible to seborrhoeic dermatitis. An abnormal immune response to P. ovale could be another explanation. Sohnle et al. have shown that P. ovale can activate complement by both the classical and the alternative pathway. A defective cell-mediated immunity to P. ovale in patients with seborrhoeic dermatitis has been demonstrated by Wikler et al. In patients with AIDS, who are known to have a diminished T-cell function, a high incidence of seborrhoeic dermatitis has been found. Activation of the alternative complement pathway by P. ovale, which does not require T-cell function, could be an explanation for the inflammatory response. I also believe that the skin lipids are important in the pathogenesis. An improvement of seborrhoeic dermatitis has been demonstrated after treatment with drugs that reduce the sebum excretion. Pityrosporum has lipase activity and may generate free fatty acids, which could also contribute to the inflammatory response. There are a number of factors which are probably important in the pathogenesis of seborrhoeic dermatitis, that is, the number of P. ovale, P. ovale lipase activity, skin lipids, immune function, heredity, atmospheric humidity and emotional state. A reduction in the number of P. ovale in patients suffering from seborrhoeic dermatitis and being treated with antimycotic treatment is, at the present state of knowledge, the best way to treat the disease.

  18. Mutational analysis of yeast profilin.

    PubMed

    Haarer, B K; Petzold, A S; Brown, S S

    1993-12-01

    We have mutated two regions within the yeast profilin gene in an effort to functionally dissect the roles of actin and phosphatidylinositol 4,5-bisphosphate (PIP2) binding in profilin function. A series of truncations was carried out at the C terminus of profilin, a region that has been implicated in actin binding. Removal of the last three amino acids nearly eliminated the ability of profilin to bind polyproline in vitro but had no dramatic in vivo effects. Thus, the extreme C terminus is implicated in polyproline binding, but the physiological relevance of this interaction is called into question. More extensive truncation, of up to eight amino acids, had in vivo effects of increasing severity and resulted in changes in conformation and expression level of the mutant profilins. However, the ability of these mutants to bind actin in vitro was not eliminated, suggesting that this region cannot be solely responsible for actin binding. We also mutagenized a region of profilin that we hypothesized might be involved in PIP2 binding. Alteration of basic amino acids in this region produced mutant profilins that functioned well in vivo. Many of these mutants, however, were unable to suppress the loss of adenylate cyclase-associated protein (Cap/Srv2p [A. Vojtek, B. Haarer, J. Field, J. Gerst, T. D. Pollard, S. S. Brown, and M. Wigler, Cell 66:497-505, 1991]), indicating that a defect could be demonstrated in vivo. In vitro assays demonstrated that the inability to suppress loss of Cap/Srv2p correlated with a defect in the interaction with actin, independently of whether PIP2 binding was reduced. Since our earlier studies of Acanthamoeba profilins suggested the importance of PIP2 binding for suppression, we conclude that both activities are implicated and that an interplay between PIP2 binding and actin binding may be important for profilin function.

  19. Influence of pesticides on yeasts colonizing leaves.

    PubMed

    Vadkertiová, Renata; Sláviková, Elena

    2011-01-01

    The effect of nine different pesticides on the growth of yeasts isolated from the leaves of fruit and forest trees was investigated. Four insecticides (with the active ingredients: thiacloprid, deltamethrin, lambdacyhalothrin, and thiamethoxam) and five fungicides (with the effective substances: bitertanol, kresoxim-methyl, mancozeb, trifloxystrobin, and cupric oxychloride) were tested. The concentrations of chemicals were those recommended by the manufacturers for the spraying of trees. The yeast strains isolated from the leaves of fruit trees were not sensitive to any of the insecticides. The majority of yeast strains isolated from the leaves of forest trees were either not sensitive or only to a small extent. While Rhodotorula mucilaginosa and Pichia anomala were not affected by any insecticide, the strains of Cryptococcus laurentii and Rhodotorula glutinis showed the highest sensitivity. The effects of fungicides on the growth of isolated yeasts were more substantial. The fungicide Dithane DG (mancozeb) completely inhibited the growth of all yeasts. All strains isolated from fruit tree leaves were more resistant to the tested fungicides than those isolated from the leaves of forest trees. The most resistant strains from the leaves of fruit trees belonged to the species Metschnikowia pulcherrima, Pichia anomala, and Saccharomyces cerevisiae, whereas Cryptococcus albidus and C. laurentii, originating from the leaves of forest trees, showed the highest sensitivity to fungicides.

  20. Ecology of pathogenic yeasts in Amazonian soil.

    PubMed Central

    Mok, W Y; Luizão, R C; do Socorro Barreto da Silva, M; Teixeira, M F; Muniz, E G

    1984-01-01

    In an investigation of Amazonian soil as a natural reservoir for pathogenic fungi, 1,949 soil samples collected from diverse geographical and ecological settings of the Brazilian Amazon Basin were analyzed for the presence of non-keratinophilic fungi by the indirect mouse inoculation procedure and for the presence of keratinophilic fungi by the hair bait technique. All soil samples were acidic with low pH values. From 12% of the soil samples, 241 yeast and yeastlike isolates pertaining to six genera and 82 species were recovered, of which 63% were Torulopsis and 26% were Candida species. Nine fungi with known pathogenic potentials were encountered among 43% (104) of the isolates: T. glabrata, C. guilliermondii, C. albicans, C. pseudotropicalis, C. stellatoidea, C. tropicalis, Rhodotorula rubra, and Wangiella dermatitidis. The yeast flora was marked by species diversity, low frequency of each species, random geographical distribution, and an apparent lack of species clustering. The composition and distribution of the yeast flora in soil differed from those of the yeast flora harbored by bats, suggesting that the Amazonian external environment and internal bat organs act as independent natural habitats for yeasts. PMID:6538774

  1. Properties of the yeast nuclear histone deacetylase.

    PubMed Central

    Sanchez del Pino, M M; Lopez-Rodas, G; Sendra, R; Tordera, V

    1994-01-01

    A nuclear histone deacetylase from yeast was partially purified and some of its characteristics were studied. Histone deacetylase activity was stimulated in vitro by high-mobility-group nonhistone chromatin proteins 1 and 2 and ubiquitin and inhibited by spermine and spermidine, whereas n-butyrate had no significant inhibitory effect. Like the mammalian enzyme, partially purified histone deacetylase from yeast was strongly inhibited by trichostatin A. However, in crude extract preparations the yeast enzyme was not inhibited and treatment with trichostatin in vivo did not show any effect, either on the histone acetylation level or on cell viability. At low ionic strength, the enzyme can be isolated as a complex of high molecular mass that is much less inhibited by trichostatin A than is partially purified histone deacetylase activity. Furthermore, radiolabelled oligonucleosomes were more efficiently deacetylated by the complex than by the low-molecular-mass form of the enzyme. The histone deacetylase activity was separated from a polyamine deacetylase activity and its specificity studied. Using h.p.l.c.-purified core histone species as substrate, histone deacetylase from yeast is able to deacetylate all core histones with a slight preference for H3. Our results support the idea that the yeast histone deacetylase may act as a high-molecular-mass complex in vivo. Images Figure 3 PMID:7980438

  2. Production of alpha-amylase by yeast

    SciTech Connect

    Thomse, K.K.

    1987-01-01

    The enzyme alpha-amylase confers to an organism the enzymatic activity for the degradation of polyglucosides with alpha-1,4 glycosidic bonds such as starch and glycogen which are among the major storage compounds in plants and animals. Most alpha-amylases are single polypeptides of molecular weights around 50,000 dalton. They are generally found in the digestive tract of animals and in germinating seeds. Among the products released upon enzymatic degradation of polyglucosides maltose, a sugar that can be utilized as carbon source by yeast, is a major constituent. A cDNA segment complementary to mouse salivary amylase messenger RNA has been inserted into the yeast expression vector pMA56 behind the promoter of the gene encoding alcohol dehydrogenase I of yeast. Yeast transformants harboring plasmids with the normal orientation of the promoter and the mouse amylase cDNA gene produce amylase and release the enzyme in free form into the culture medium. Approximately 90% of the amylase activity is found in the medium. Yeast strains carrying MAL allele and transformed with a plasmid which directed the synthesis of mouse alpha-amylase were tested on plates containing starch and in batch fermentations using different high molecular weight sugars and oligosaccharides as carbon source. The results of these experiments will be discussed. (Refs. 21).

  3. Yeasts associated with Sardinian ewe's dairy products.

    PubMed

    Cosentino, S; Fadda, M E; Deplano, M; Mulargia, A F; Palmas, F

    2001-09-19

    In the present work, the occurrence of yeasts in different types of typical Sardinian ewe's cheeses (32 samples of pecorino, 32 of caciotta, 40 of feta, 56 of ricotta) was determined. For the strains isolated the following properties were studied: proteolytic and lipolytic activities, the ability to grow at different temperatures, different concentrations of salt, and to assimilate and/or ferment compounds like lactate, citrate, lactose, glucose, galactose, lactic acid. Of 160 samples analysed, 76.2% yielded growth of yeasts. Yeast counts showed a certain variability among the samples. The highest levels were observed in caciotta and feta cheeses. A total of 281 strains belonging to 16 genera and 25 species were identified. In general, Debaryomyces hansenii was the dominant species, representing 28.8% of the total isolates. Other frequently appearing species were Geotrichum candidum, Kluyveromyces lactis and K. marxianus. Other genera encountered were Pichia, Candida, Dekkera, Yarrowia and Rhodotorula. With regard to the biochemical and technological properties of the yeasts, only K. lactis, K. marxianus and Dek. anomala assimilated and fermented lactose, whereas the majority of the species assimilated lactic acid. The assimilation of citrate was a characteristic of D. hansenii, R. rubra and Y. lipolytica. On the whole, the yeasts were weakly proteolytic while lipolytic activity was present in several species. A high percentage of strains showed a certain tolerance to low temperatures while only some strains of D. hansenii and K. lactis were able to grow at a 10% NaCl concentration.

  4. Yeast fuel cell: Application for desalination

    NASA Astrophysics Data System (ADS)

    Mardiana, Ummy; Innocent, Christophe; Cretin, Marc; Buchari, Buchari; Gandasasmita, Suryo

    2016-02-01

    Yeasts have been implicated in microbial fuel cells as biocatalysts because they are non-pathogenic organisms, easily handled and robust with a good tolerance in different environmental conditions. Here we investigated baker's yeast Saccharomyces cerevisiae through the oxidation of glucose. Yeast was used in the anolyte, to transfer electrons to the anode in the presence of methylene blue as mediator whereas K3Fe(CN)6 was used as an electron acceptor for the reduction reaction in the catholyte. Power production with biofuel cell was coupled with a desalination process. The maximum current density produced by the cell was 88 mA.m-2. In those conditions, it was found that concentration of salt was removed 64% from initial 0.6 M after 1-month operation. This result proves that yeast fuel cells can be used to remove salt through electrically driven membrane processes and demonstrated that could be applied for energy production and desalination. Further developments are in progress to improve power output to make yeast fuel cells applicable for water treatment.

  5. Stress responses in yeasts: what rules apply?

    PubMed

    González-Párraga, Pilar; Sánchez-Fresneda, Ruth; Martínez-Esparza, María; Argüelles, Juan-Carlos

    2008-04-01

    Living organisms have evolved a complex network of mechanisms to face the unforeseen nutritional and environmental circumstances imposed on their natural habitats, commonly termed "stress". To learn more about these mechanisms, several challenges are usually applied in the laboratory, namely nutrient starvation, heat shock, dehydration, oxidative exposures, etc. Yeasts are chosen as convenient models for studying stress phenomena because of their simple cellular organization and the amenability to genetic analysis. A vast scientific literature has recently appeared on the defensive cellular responses to stress. However, this plethora of studies covers quite different experimental conditions, making any conclusions open to dispute. In fact, the term "yeast stress" is rather confusing, since the same treatment may be very stressful or irrelevant, depending on the yeast. Customary expressions such as "gentle stress" (non-lethal) or "severe stress" (potentially lethal) should be precisely clarified. In turn, although prototypic yeasts share a common repertoire of signalling responsive pathways to stress, these are adapted to the specific ecological niche and biological activity of each particular species. What does "stress" really mean? Before we go any deeper, we have to define this uncertain meaning along with a proper explanation concerning the terms and conditions used in research on yeast stress.

  6. Anaerobic digestion of food waste using yeast.

    PubMed

    Suwannarat, Jutarat; Ritchie, Raymond J

    2015-08-01

    Fermentative breakdown of food waste seems a plausible alternative to feeding food waste to pigs, incineration or garbage disposal in tourist areas. We determined the optimal conditions for the fermentative breakdown of food waste using yeast (Saccharomyces cerevisiae) in incubations up to 30days. Yeast efficiently broke down food waste with food waste loadings as high as 700g FW/l. The optimum inoculation was ≈46×10(6)cells/l of culture with a 40°C optimum (25-40°C). COD and BOD were reduced by ≈30-50%. Yeast used practically all the available sugars and reduced proteins and lipids by ≈50%. Yeast was able to metabolize lipids much better than expected. Starch was mobilized after very long term incubations (>20days). Yeast was effective in breaking down the organic components of food waste but CO2 gas and ethanol production (≈1.5%) were only significant during the first 7days of incubations.

  7. Evidence for yeast autophagy during simulation of sparkling wine aging: a reappraisal of the mechanism of yeast autolysis in wine.

    PubMed

    Cebollero, Eduardo; Carrascosa, Alfonso V; Gonzalez, Ramon

    2005-01-01

    Yeast autolysis is the source of several molecules responsible for the quality of wines aged in contact with yeast cells. However, the mechanisms of yeast autolysis during wine aging are not completely understood. All descriptions of yeast autolysis in enological conditions emphasize the disturbance of cell organization as the starting event in the internal digestion of the cell, while no reference to autophagy is found in wine-related literature. By using yeast mutants defective in the autophagic or the Cvt pathways we have demonstrated that autophagy does take place in wine production conditions. This finding has implications for the genetic improvement of yeasts for accelerated autolysis.

  8. Yeasts and yeast-like organisms associated with fruits and blossoms of different fruit trees.

    PubMed

    Vadkertiová, Renáta; Molnárová, Jana; Vránová, Dana; Sláviková, Elena

    2012-12-01

    Yeasts are common inhabitants of the phyllosphere, but our knowledge of their diversity in various plant organs is still limited. This study focused on the diversity of yeasts and yeast-like organisms associated with matured fruits and fully open blossoms of apple, plum, and pear trees, during 2 consecutive years at 3 localities in southwest Slovakia. The occurrence of yeasts and yeast-like organisms in fruit samples was 2½ times higher and the yeast community more diverse than that in blossom samples. Only 2 species (Aureobasidium pullulans and Metschnikowia pulcherrima) occurred regularly in the blossom samples, whereas Galactomyces candidus, Hanseniaspora guilliermondii, Hanseniaspora uvarum, M. pulcherrima, Pichia kluyveri, Pichia kudriavzevii, and Saccharomyces cerevisiae were the most frequently isolated species from the fruit samples. The ratio of the number of samples where only individual species were present to the number of samples where 2 or more species were found (consortium) was counted. The occurrence of individual species in comparison with consortia was much higher in blossom samples than in fruit samples. In the latter, consortia predominated. Aureobasidium pullulans, M. pulcherrima, and S. cerevisiae, isolated from both the fruits and blossoms, can be considered as resident yeast species of various fruit tree species cultivated in southwest Slovakia localities.

  9. Biofuels. Altered sterol composition renders yeast thermotolerant.

    PubMed

    Caspeta, Luis; Chen, Yun; Ghiaci, Payam; Feizi, Amir; Buskov, Steen; Hallström, Björn M; Petranovic, Dina; Nielsen, Jens

    2014-10-03

    Ethanol production for use as a biofuel is mainly achieved through simultaneous saccharification and fermentation by yeast. Operating at ≥40°C would be beneficial in terms of increasing efficiency of the process and reducing costs, but yeast does not grow efficiently at those temperatures. We used adaptive laboratory evolution to select yeast strains with improved growth and ethanol production at ≥40°C. Sequencing of the whole genome, genome-wide gene expression, and metabolic-flux analyses revealed a change in sterol composition, from ergosterol to fecosterol, caused by mutations in the C-5 sterol desaturase gene, and increased expression of genes involved in sterol biosynthesis. Additionally, large chromosome III rearrangements and mutations in genes associated with DNA damage and respiration were found, but contributed less to the thermotolerant phenotype.

  10. Complete biosynthesis of opioids in yeast

    PubMed Central

    Galanie, Stephanie; Thodey, Kate; Trenchard, Isis J.; Interrante, Maria Filsinger; Smolke, Christina D.

    2016-01-01

    Opioids are the primary drugs used in Western medicine for pain management and palliative care. Farming of opium poppies remains the sole source of these essential medicines despite diverse market demands and uncertainty in crop yields due to weather, climate change, and pests. Here, we engineered yeast to produce the selected opioid compounds thebaine and hydrocodone starting from sugar. All work was conducted in a laboratory that is permitted and secured for work with controlled substances. We combined enzyme discovery, enzyme engineering, and pathway and strain optimization to realize full opiate biosynthesis in yeast. The resulting opioid biosynthesis strains required expression of 21 (thebaine) and 23 (hydrocodone) enzyme activities from plants, mammals, bacteria, and yeast itself. This is a proof-of-principle, and major hurdles remain before optimization and scale up could be achieved. Open discussions of options for governing this technology are also needed in order to responsibly realize alternative supplies for these medically relevant compounds. PMID:26272907

  11. Molecular control of fission yeast cytokinesis.

    PubMed

    Rincon, Sergio A; Paoletti, Anne

    2016-05-01

    Cytokinesis gives rise to two independent daughter cells at the end of the cell division cycle. The fission yeast Schizosaccharomyces pombe has emerged as one of the most powerful systems to understand how cytokinesis is controlled molecularly. Like in most eukaryotes, fission yeast cytokinesis depends on an acto-myosin based contractile ring that assembles at the division site under the control of spatial cues that integrate information on cell geometry and the position of the mitotic apparatus. Cytokinetic events are also tightly coordinated with nuclear division by the cell cycle machinery. These spatial and temporal regulations ensure an equal cleavage of the cytoplasm and an accurate segregation of the genetic material in daughter cells. Although this model system has specificities, the basic mechanisms of contractile ring assembly and function deciphered in fission yeast are highly valuable to understand how cytokinesis is controlled in other organisms that rely on a contractile ring for cell division.

  12. Yeast Interactions in Inoculated Wine Fermentation

    PubMed Central

    Ciani, Maurizio; Capece, Angela; Comitini, Francesca; Canonico, Laura; Siesto, Gabriella; Romano, Patrizia

    2016-01-01

    The use of selected starter culture is widely diffused in winemaking. In pure fermentation, the ability of inoculated Saccharomyces cerevisiae to suppress the wild microflora is one of the most important feature determining the starter ability to dominate the process. Since the wine is the result of the interaction of several yeast species and strains, many studies are available on the effect of mixed cultures on the final wine quality. In mixed fermentation the interactions between the different yeasts composing the starter culture can led the stability of the final product and the analytical and aromatic profile. In the present review, we will discuss the recent developments regarding yeast interactions in pure and in mixed fermentation, focusing on the influence of interactions on growth and dominance in the process. PMID:27148235

  13. Cytotoxic Mechanism of Selenomethionine in Yeast*

    PubMed Central

    Kitajima, Toshihiko; Jigami, Yoshifumi; Chiba, Yasunori

    2012-01-01

    Although selenium is an essential element, its excessive uptake is detrimental to living organisms. The significance of selenium for living organisms has been exploited for various purposes. However, the molecular basis of selenium toxicity is not completely understood. Here, we applied a capillary electrophoresis time-of-flight mass spectrometry-based metabolomics approach to analysis of yeast cells treated with selenomethionine. The data indicated that intracellular thiol compounds are significantly decreased, and diselenide and selenosulfide compounds are increased in selenomethionine-treated cells. The growth defect induced by selenomethionine was recovered by extracellular addition of cysteine and by genetic modification of yeast cells that have an additional de novo synthetic pathway for cysteine. Because cysteine is an intermediate of thiol compounds, these results suggested that the loss of a reduced form of thiol compounds due to selenomethionine causes a growth defect of yeast cells. PMID:22311978

  14. Mitochondrial movement and inheritance in budding yeast.

    PubMed

    Boldogh, Istvan R; Fehrenbacher, Kammy L; Yang, Hyeong-Cheol; Pon, Liza A

    2005-07-18

    Mitochondria are essential organelles that perform fundamental cellular functions including aerobic energy mobilization, fatty acid oxidation, amino acid metabolism, heme biosynthesis and apoptosis. Mitochondria cannot be synthesized de novo. Therefore, the inheritance of this organelle is an essential part of the cell cycle; that is, daughter cells that do not inherit mitochondria will not survive. The budding yeast, Saccharomyces cerevisiae, is a facultative aerobe that can tolerate mitochondrial mutations that would be lethal in other organisms. Therefore, yeast has been used extensively to study inheritance and segregation of mitochondria. As a result, much of what we know regarding mitochondrial inheritance has been uncovered using yeast as a model system. Here, we describe the latest developments in mitochondrial motility and inheritance.

  15. Complete biosynthesis of opioids in yeast.

    PubMed

    Galanie, Stephanie; Thodey, Kate; Trenchard, Isis J; Filsinger Interrante, Maria; Smolke, Christina D

    2015-09-04

    Opioids are the primary drugs used in Western medicine for pain management and palliative care. Farming of opium poppies remains the sole source of these essential medicines, despite diverse market demands and uncertainty in crop yields due to weather, climate change, and pests. We engineered yeast to produce the selected opioid compounds thebaine and hydrocodone starting from sugar. All work was conducted in a laboratory that is permitted and secured for work with controlled substances. We combined enzyme discovery, enzyme engineering, and pathway and strain optimization to realize full opiate biosynthesis in yeast. The resulting opioid biosynthesis strains required the expression of 21 (thebaine) and 23 (hydrocodone) enzyme activities from plants, mammals, bacteria, and yeast itself. This is a proof of principle, and major hurdles remain before optimization and scale-up could be achieved. Open discussions of options for governing this technology are also needed in order to responsibly realize alternative supplies for these medically relevant compounds.

  16. Yeast metabolic engineering for hemicellulosic ethanol production.

    PubMed

    Van Vleet, J H; Jeffries, T W

    2009-06-01

    Efficient fermentation of hemicellulosic sugars is critical for the bioconversion of lignocellulosics to ethanol. Efficient sugar uptake through the heterologous expression of yeast and fungal xylose/glucose transporters can improve fermentation if other metabolic steps are not rate limiting. Rectification of cofactor imbalances through heterologous expression of fungal xylose isomerase or modification of cofactor requirements in the yeast oxidoreductase pathway can reduce xylitol production while increasing ethanol yields, but these changes often occur at the expense of xylose utilization rates. Genetic engineering and evolutionary adaptation to increase glycolytic flux coupled with transcriptomic and proteomic studies have identified targets for further modification, as have genomic and metabolic engineering studies in native xylose fermenting yeasts.

  17. [The yeast biofilm in human medicine].

    PubMed

    Růzicka, Filip; Holá, Veronika; Votava, Miroslav

    2007-08-01

    In recent years, the role of Candida yeasts as causative agents of nosocomial infections has increased. One of the important virulence factors contributing to the development of such infections is biofilm production. This virulence factor enables yeast to colonize both native surfaces and artificial implants. The most common sources of infection are patients themselves, in particular the gastrointestinal tract and skin. The vectors of exogenous yeast infections are predominantly the hands of the health personnel and contaminated medical instruments. The adhesion of yeasts to the implant surfaces is determined both by implant surface and yeast characteristics. This is followed by proliferation and production of microcolonies and extracellular matrix. The final biofilm structure is also influenced by the production of hyphae and pseudohyphae. The entire process of biofilm production is controlled by numerous regulatory systems, with the key role being played by the quorum sensing system. Like the adhered bacterial cultures, candidas growing in the form of a biofilm are highly resistant to antimicrobial therapy. Resistance of yeast biofilms to antifungals is a complex process with multiple contributing factors. These are especially increased gene expression (e.g. genes encoding the so called multidrug efflux pumps), limited penetration of substances through the extracellular matrix, inhibited cell growth and altered microenvironment in deeper biofilm layers. The concentrations of antifungals able to effectively affect the biofilm cells exceed, by several orders of magnitude, the values of conventionally determined MICs. High biofilm resistance results in ineffective antifungal therapy of biofilm infections. Therefore, if possible, the colonized implant should be removed. Conservative therapy should involve antifungals with a proven effect on the biofilm (e.g. caspofungin). The most effective measure in fighting biofilm infections is prevention, especially adhering to

  18. Predicting the fission yeast protein interaction network.

    PubMed

    Pancaldi, Vera; Saraç, Omer S; Rallis, Charalampos; McLean, Janel R; Převorovský, Martin; Gould, Kathleen; Beyer, Andreas; Bähler, Jürg

    2012-04-01

    A systems-level understanding of biological processes and information flow requires the mapping of cellular component interactions, among which protein-protein interactions are particularly important. Fission yeast (Schizosaccharomyces pombe) is a valuable model organism for which no systematic protein-interaction data are available. We exploited gene and protein properties, global genome regulation datasets, and conservation of interactions between budding and fission yeast to predict fission yeast protein interactions in silico. We have extensively tested our method in three ways: first, by predicting with 70-80% accuracy a selected high-confidence test set; second, by recapitulating interactions between members of the well-characterized SAGA co-activator complex; and third, by verifying predicted interactions of the Cbf11 transcription factor using mass spectrometry of TAP-purified protein complexes. Given the importance of the pathway in cell physiology and human disease, we explore the predicted sub-networks centered on the Tor1/2 kinases. Moreover, we predict the histidine kinases Mak1/2/3 to be vital hubs in the fission yeast stress response network, and we suggest interactors of argonaute 1, the principal component of the siRNA-mediated gene silencing pathway, lost in budding yeast but preserved in S. pombe. Of the new high-quality interactions that were discovered after we started this work, 73% were found in our predictions. Even though any predicted interactome is imperfect, the protein network presented here can provide a valuable basis to explore biological processes and to guide wet-lab experiments in fission yeast and beyond. Our predicted protein interactions are freely available through PInt, an online resource on our website (www.bahlerlab.info/PInt).

  19. Predicting the Fission Yeast Protein Interaction Network

    PubMed Central

    Pancaldi, Vera; Saraç, Ömer S.; Rallis, Charalampos; McLean, Janel R.; Převorovský, Martin; Gould, Kathleen; Beyer, Andreas; Bähler, Jürg

    2012-01-01

    A systems-level understanding of biological processes and information flow requires the mapping of cellular component interactions, among which protein–protein interactions are particularly important. Fission yeast (Schizosaccharomyces pombe) is a valuable model organism for which no systematic protein-interaction data are available. We exploited gene and protein properties, global genome regulation datasets, and conservation of interactions between budding and fission yeast to predict fission yeast protein interactions in silico. We have extensively tested our method in three ways: first, by predicting with 70–80% accuracy a selected high-confidence test set; second, by recapitulating interactions between members of the well-characterized SAGA co-activator complex; and third, by verifying predicted interactions of the Cbf11 transcription factor using mass spectrometry of TAP-purified protein complexes. Given the importance of the pathway in cell physiology and human disease, we explore the predicted sub-networks centered on the Tor1/2 kinases. Moreover, we predict the histidine kinases Mak1/2/3 to be vital hubs in the fission yeast stress response network, and we suggest interactors of argonaute 1, the principal component of the siRNA-mediated gene silencing pathway, lost in budding yeast but preserved in S. pombe. Of the new high-quality interactions that were discovered after we started this work, 73% were found in our predictions. Even though any predicted interactome is imperfect, the protein network presented here can provide a valuable basis to explore biological processes and to guide wet-lab experiments in fission yeast and beyond. Our predicted protein interactions are freely available through PInt, an online resource on our website (www.bahlerlab.info/PInt). PMID:22540037

  20. Biochemical Comparison of Commercial Selenium Yeast Preparations.

    PubMed

    Fagan, Sheena; Owens, Rebecca; Ward, Patrick; Connolly, Cathal; Doyle, Sean; Murphy, Richard

    2015-08-01

    The trace mineral selenium (Se) is an essential element for human and animal nutrition. The addition of Se to the diet through dietary supplements or fortified food/feed is increasingly common owing to the often sub-optimal content of standard diets of many countries. Se supplements commercially available include the inorganic mineral salts such as sodium selenite or selenate, and organic forms such as Se-enriched yeast. Today, Se yeast is produced by several manufacturers and has become the most widely used source of Se for human supplementation and is also widely employed in animal nutrition where approval in all species has been granted by regulatory bodies such as the European Food Safety Authority (EFSA). Characterisation and comparison of Se-enriched yeast products has traditionally been made by quantifying total selenomethionine (SeMet) content. A disadvantage of this approach, however, is that it does not consider the effects of Se deposition on subsequent digestive availability. In this study, an assessment was made of the water-soluble extracts of commercially available Se-enriched yeast samples for free, peptide-bound and total water-soluble SeMet. Using LC-MS/MS, a total of 62 Se-containing proteins were identified across four Se yeast products, displaying quantitative/qualitative changes in abundance relative to the certified reference material, SELM-1 (P value <0.05; fold change ≥2). Overall, the study indicates that significant differences exist between Se yeast products in terms of SeMet content, Se-containing protein abundance and associated metabolic pathways.

  1. Yeast 14-3-3 proteins.

    PubMed

    van Heusden, G Paul H; Steensma, H Yde

    2006-02-01

    14-3-3 proteins form a family of highly conserved proteins which are present in all eukaryotic organisms investigated, often in multiple isoforms, up to 13 in some plants. They interact with more than 200 different, mostly phosphorylated proteins. The molecular consequences of 14-3-3 binding are diverse: this binding may result in stabilization of the active or inactive phosphorylated form of the protein, to a conformational alteration leading to activation or inhibition, to a different subcellular localization, to the interaction with other proteins or to shielding of binding sites. The binding partners, and hence the 14-3-3 proteins, are involved in almost every cellular process and 14-3-3 proteins have been linked to several diseases, such as cancer, Alzheimer's disease, the neurological Miller-Dieker and spinocerebellar ataxia type 1 diseases and bovine spongiform encephalopathy (BSE). The yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe both have two genes encoding 14-3-3 proteins, BMH1 and BMH2 and rad24 and rad25, respectively. In these yeasts, 14-3-3 proteins are essential in most laboratory strains. As in higher eukaryotes, yeast 14-3-3 proteins bind to numerous proteins involved in a variety of cellular processes. Recent genome-wide studies on yeast strains with impaired 14-3-3 function support the participation of 14-3-3 proteins in numerous yeast cellular processes. Given the high evolutionary conservation of the 14-3-3 proteins, the experimental accessibility and relative simplicity of yeasts make them excellent model organisms for elucidating the function of the 14-3-3 protein family.

  2. 'Red Yeast Rice' Statin Alternative Not Harmless Either, Study Says

    MedlinePlus

    ... medlineplus.gov/news/fullstory_163221.html 'Red Yeast Rice' Statin Alternative Not Harmless Either, Study Says The ... A natural cholesterol-lowering supplement called red yeast rice could pose the same health risks to users ...

  3. [Invasive yeast infections in neutropenic patients].

    PubMed

    Ruiz Camps, Isabel; Jarque, Isidro

    2016-01-01

    Invasive fungal diseases caused by yeasts still play an important role in the morbidity and mortality in neutropenic patients with haematological malignancies. Although the overall incidence of invasive candidiasis has decreased due to widespread use of antifungal prophylaxis, the incidence of non-Candida albicans Candida species is increasing compared with that of C.albicans, and mortality of invasive candidiasis continues to be high. In addition, there has been an increase in invasive infections caused by an array of uncommon yeasts, including species of the genus Malassezia, Rhodotorula, Trichosporon and Saprochaete, characterised by their resistance to echinocandins and poor prognosis.

  4. Principles of chromosomal organization: lessons from yeast

    PubMed Central

    Zimmer, Christophe

    2011-01-01

    The spatial organization of genes and chromosomes plays an important role in the regulation of several DNA processes. However, the principles and forces underlying this nonrandom organization are mostly unknown. Despite its small dimension, and thanks to new imaging and biochemical techniques, studies of the budding yeast nucleus have led to significant insights into chromosome arrangement and dynamics. The dynamic organization of the yeast genome during interphase argues for both the physical properties of the chromatin fiber and specific molecular interactions as drivers of nuclear order. PMID:21383075

  5. DNA replication in yeast is stochastic

    NASA Astrophysics Data System (ADS)

    Cheng-Hsin Yang, Scott; Rhind, Nicholas; Bechhoefer, John

    2010-03-01

    Largely on the basis of a simple --- perhaps too simple --- analysis of microarray-chip experiments, people have concluded that DNA replication in budding yeast (S. cerevisiae) is a nearly deterministic process, in which the position and activation time of each origin of replication is pre-determined. In this talk, we introduce a more quantitative approach to the analysis of microarray data. Applying our new methods to budding yeast, we show that the microarray data imply a picture of replication where the timing of origin activation is highly stochastic. We then propose a physical model (the ``multiple-initiator model") to account for the observed probability distributions of origin- activation timing.

  6. Genetic diversity of the yeast Candida utilis.

    PubMed

    Stoltenburg, R; Klinner, U; Ritzerfeld, P; Zimmermann, M; Emeis, C C

    1992-12-01

    The electrophoretic karyotypes and some mtDNA restriction fragment patterns of 13 strains of Candida utilis and one strain of Hansenula jadinii were compared. PFGE separations revealed remarkable chromosome length polymorphisms between two groups of strains suggesting that perhaps they do not belong to the same species. However, all strains had the same or similar EcoRI, HindIII and BamHI mtDNA restriction patterns. The mtDNA genomes had an average size range of 55 kb. These results support the supposition that C. utilis is a yeast with a highly variable electrophoretic karyotype as already known for another imperfect yeast species, Candida albicans.

  7. Overwintering of Vineyard Yeasts: Survival of Interacting Yeast Communities in Grapes Mummified on Vines

    PubMed Central

    Sipiczki, Matthias

    2016-01-01

    The conversion of grape must into wine involves the development and succession of yeast populations differing in species composition. The initial population is formed by vineyard strains which are washed into the must from the crushed grapes and then completed with yeasts coming from the cellar environment. As the origin and natural habitat of the vineyard yeasts are not fully understood, this study addresses the possibility, that grape yeasts can be preserved in berries left behind on vines at harvest until the spring of the next year. These berries become mummified during the winter on the vines. To investigate whether yeasts can survive in these overwintering grapes, mummified berries were collected in 16 localities in the Tokaj wine region (Hungary-Slovakia) in early March. The collected berries were rehydrated to recover viable yeasts by plating samples onto agar plates. For the detection of minority species which would not be detected by direct plating, an enrichment step repressing the propagation of alcohol-sensitive yeasts was also included in the process. The morphological, physiological, and molecular analysis identified 13 basidiomycetous and 23 ascomycetous species including fermentative yeasts of wine-making relevance among the 3879 isolates. The presence of viable strains of these species demonstrates that the grapes mummified on the vine can serve as a safe reservoir of yeasts, and may contribute to the maintenance of grape-colonizing yeast populations in the vineyard over years, parallel with other vectors and habitats. All basidiomycetous species were known phylloplane yeasts. Three Hanseniaspora species and pigmented Metschnikowia strains were the most frequent ascomycetes. Other fermentative yeasts of wine-making relevance were detected only in the enrichment cultures. Saccharomyces (S. paradoxus, S. cerevisiae, and S. uvarum) were recovered from 13% of the samples. No Candida zemplinina was found. The isolates with Aureobasidium morphology

  8. Biochemical characteristics of osmophilic yeasts isolated from pollens and honey.

    PubMed

    Park, Y K; Koo, M H; Oliveira, I M

    1996-11-01

    A total of 1752 strains of osmophilic yeasts were isolated from honey and pollens. Forty-three strains of osmophilic yeasts produced polyols, among which 6 strains produced erythritol in good yields. On the other hand, 52 osmophilic yeasts converted sucrose to fructooligosaccharides, among which 8 strains produced both extra and intracellular beta-fructofuranosidase, which converted sucrose to fructooligosaccharides. This investigation concluded that osmophilic yeasts converted sucrose not only to polyols, but also to fructooligosaccharides in good yields.

  9. Further modifications of the auxanographic method for identification of yeasts.

    PubMed Central

    Mickelsen, P A; McCarthy, L R; Propst, M A

    1977-01-01

    A modified auxanographic carbohydrate assimilation procedure for the identification of medically important yeasts is described. This method employs a heavy inoculum of unstarved yeasts, autoclaved yeast assimilation medium, pour plates of shallow depth, and commercially available carbohydrate-impregnated disks. The accuracy of this procedure was established in a comparison with the Wickerham broth method. PMID:853120

  10. Further modifications of the auxanographic method for identification of yeasts.

    PubMed

    Mickelsen, P A; McCarthy, L R; Propst, M A

    1977-03-01

    A modified auxanographic carbohydrate assimilation procedure for the identification of medically important yeasts is described. This method employs a heavy inoculum of unstarved yeasts, autoclaved yeast assimilation medium, pour plates of shallow depth, and commercially available carbohydrate-impregnated disks. The accuracy of this procedure was established in a comparison with the Wickerham broth method.

  11. Triacetic acid lactone production in industrial Saccharomyces yeast strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Triacetic acid lactone (TAL) is a potential platform chemical that can be produced in yeast. To evaluate the potential for industrial yeast strains to produce TAL, the g2ps1 gene encoding 2-pyrone synthase was transformed into thirteen industrial yeast strains of varied genetic background. TAL produ...

  12. Drosophila-associated yeast species in vineyard ecosystems.

    PubMed

    Lam, Samuel S T H; Howell, Kate S

    2015-10-01

    Yeast activity during wine fermentation directly contributes to wine quality, but the source and movement of yeasts in vineyards and winery environments have not been resolved. Here, we investigate the yeast species associated with the Drosophila insect vector to help understand yeast dispersal and persistence. Drosophila are commonly found in vineyards and are known to have a mutualistic relationship with yeasts in other ecosystems. Drosophilids were collected from vineyards, grape waste (marc) piles and wineries during grape harvest. Captured flies were identified morphologically, and their associated yeasts were identified. Drosophila melanogaster/D. simulans, D. hydei and Scaptodrosophila lativittata were identified in 296 captured Drosophila flies. These flies were associated with Metschnikowia pulcherrima, Hanseniaspora uvarum, Torulaspora delbrueckii and H. valbyensis yeasts. Yeast and Drosophila species diversity differed between collection locations (vineyard and marc: R = 0.588 for Drosophila and R = 0.644 for yeasts). Surprisingly, the primary wine fermentation yeast, Saccharomyces cerevisiae, was not isolated. Drosophila flies are preferentially associated with different yeast species in the vineyard and winery environments, and this association may help the movement and dispersal of yeast species in the vineyard and winery ecosystem.

  13. 21 CFR 573.750 - Pichia pastoris dried yeast.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Pichia pastoris dried yeast. 573.750 Section 573... Food Additive Listing § 573.750 Pichia pastoris dried yeast. (a) Identity. The food additive Pichia pastoris dried yeast may be used in feed formulations of broiler chickens as a source of protein not...

  14. 21 CFR 573.750 - Pichia pastoris dried yeast.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Pichia pastoris dried yeast. 573.750 Section 573... Food Additive Listing § 573.750 Pichia pastoris dried yeast. (a) Identity. The food additive Pichia pastoris dried yeast may be used in feed formulations of broiler chickens as a source of protein not...

  15. 21 CFR 573.750 - Pichia pastoris dried yeast.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Pichia pastoris dried yeast. 573.750 Section 573... Food Additive Listing § 573.750 Pichia pastoris dried yeast. (a) Identity. The food additive Pichia pastoris dried yeast may be used in feed formulations of broiler chickens as a source of protein not...

  16. 21 CFR 573.750 - Pichia pastoris dried yeast.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Pichia pastoris dried yeast. 573.750 Section 573... Food Additive Listing § 573.750 Pichia pastoris dried yeast. (a) Identity. The food additive Pichia pastoris dried yeast may be used in feed formulations of broiler chickens as a source of protein not...

  17. 21 CFR 573.750 - Pichia pastoris dried yeast.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Pichia pastoris dried yeast. 573.750 Section 573... Food Additive Listing § 573.750 Pichia pastoris dried yeast. (a) Identity. The food additive Pichia pastoris dried yeast may be used in feed formulations of broiler chickens as a source of protein not...

  18. Fission yeast meets a legend in Kobe: report of the Eighth International Fission Yeast Meeting.

    PubMed

    Asakawa, Haruhiko; Yamamoto, Takaharu G; Hiraoka, Yasushi

    2015-12-01

    The Eighth International Fission Yeast Meeting, which was held at Ikuta Shrine Hall in Kobe, Japan, from 21 to 26 June 2015, was attended by 327 fission yeast researchers from 25 countries (190 overseas and 137 domestic participants). At this meeting, 124 talks were held and 145 posters were presented. In addition, newly developed database tools were introduced to the community during a workshop. Researchers shared cutting-edge knowledge across broad fields of study, ranging from molecules to evolution, derived from the superior model organism commonly used within the fission yeast community. Intensive discussions and constructive suggestions generated in this meeting will surely advance the understanding of complex biological systems in fission yeast, extending to general eukaryotes.

  19. Dynamic changes in brewing yeast cells in culture revealed by statistical analyses of yeast morphological data.

    PubMed

    Ohnuki, Shinsuke; Enomoto, Kenichi; Yoshimoto, Hiroyuki; Ohya, Yoshikazu

    2014-03-01

    The vitality of brewing yeasts has been used to monitor their physiological state during fermentation. To investigate the fermentation process, we used the image processing software, CalMorph, which generates morphological data on yeast mother cells and bud shape, nuclear shape and location, and actin distribution. We found that 248 parameters changed significantly during fermentation. Successive use of principal component analysis (PCA) revealed several important features of yeast, providing insight into the dynamic changes in the yeast population. First, PCA indicated that much of the observed variability in the experiment was summarized in just two components: a change with a peak and a change over time. Second, PCA indicated the independent and important morphological features responsible for dynamic changes: budding ratio, nucleus position, neck position, and actin organization. Thus, the large amount of data provided by imaging analysis can be used to monitor the fermentation processes involved in beer and bioethanol production.

  20. Schizosaccharomyces japonicus: the fission yeast is a fusion of yeast and hyphae.

    PubMed

    Niki, Hironori

    2014-03-01

    The clade of Schizosaccharomyces includes 4 species: S. pombe, S. octosporus, S. cryophilus, and S. japonicus. Although all 4 species exhibit unicellular growth with a binary fission mode of cell division, S. japonicus alone is dimorphic yeast, which can transit from unicellular yeast to long filamentous hyphae. Recently it was found that the hyphal cells response to light and then synchronously activate cytokinesis of hyphae. In addition to hyphal growth, S. japonicas has many properties that aren't shared with other fission yeast. Mitosis of S. japonicas is referred to as semi-open mitosis because dynamics of nuclear membrane is an intermediate mode between open mitosis and closed mitosis. Novel genetic tools and the whole genomic sequencing of S. japonicas now provide us with an opportunity for revealing unique characters of the dimorphic yeast.

  1. Glucose-Induced Acidification in Yeast Cultures

    ERIC Educational Resources Information Center

    Myers, Alan; Bourn, Julia; Pool, Brynne

    2005-01-01

    We present an investigation (for A-level biology students and equivalent) into the mechanism of glucose-induced extracellular acidification in unbuffered yeast suspensions. The investigation is designed to enhance understanding of aspects of the A-level curriculum that relate to the phenomenon (notably glucose catabolism) and to develop key skills…

  2. Yeast metallothionein function in metal ion detoxification.

    PubMed

    Ecker, D J; Butt, T R; Sternberg, E J; Neeper, M P; Debouck, C; Gorman, J A; Crooke, S T

    1986-12-25

    A genetic approach was taken to test the function of yeast metallothionein in metal ion detoxification. A yeast strain was constructed in which the metallothionein locus was deleted (cup1 delta). The cup1 delta strain was complemented with normal or mutant metallothionein genes under normal or constitutive regulatory control on high copy episomal plasmids. Metal resistance of the cup1 delta strain with and without the metallothionein-expressing vectors was analyzed. The normally regulated metallothionein gene conferred resistance only to copper (1000-fold); constitutively expressed metallothionein conferred resistance to both copper (500-fold) and cadmium (1000-fold), but not to mercury, zinc, silver, cobalt, nickel, gold, platinum, lanthanum, uranium, or tin. Two mutant versions of the metallothionein gene were constructed and tested for their ability to confer metal resistance in the cup1 delta background. The first had a deletion of a highly conserved amino acid sequence (Lys-Lys-Ser-Cys-Cys-Ser). The second was a hybrid gene consisting of the sequences coding for the first 20 amino acids of the yeast protein fused to the monkey metallothionein gene. Expression of these genes under the CUP1 promoter provided significant protection from copper, but none of the other metals tested. These results demonstrate that there is significant flexibility in the structural requirements for metallothionein to function in copper detoxification and that yeast metallothionein is also capable of detoxifying cadmium under conditions of constitutive expression.

  3. Actin and Endocytosis in Budding Yeast

    PubMed Central

    Goode, Bruce L.; Eskin, Julian A.; Wendland, Beverly

    2015-01-01

    Endocytosis, the process whereby the plasma membrane invaginates to form vesicles, is essential for bringing many substances into the cell and for membrane turnover. The mechanism driving clathrin-mediated endocytosis (CME) involves > 50 different protein components assembling at a single location on the plasma membrane in a temporally ordered and hierarchal pathway. These proteins perform precisely choreographed steps that promote receptor recognition and clustering, membrane remodeling, and force-generating actin-filament assembly and turnover to drive membrane invagination and vesicle scission. Many critical aspects of the CME mechanism are conserved from yeast to mammals and were first elucidated in yeast, demonstrating that it is a powerful system for studying endocytosis. In this review, we describe our current mechanistic understanding of each step in the process of yeast CME, and the essential roles played by actin polymerization at these sites, while providing a historical perspective of how the landscape has changed since the preceding version of the YeastBook was published 17 years ago (1997). Finally, we discuss the key unresolved issues and where future studies might be headed. PMID:25657349

  4. Antarctic Yeasts: Biodiversity and Potential Applications

    NASA Astrophysics Data System (ADS)

    Shivaji, S.; Prasad, G. S.

    This review is an attempt in cataloguing the diversity of yeasts in Antarctica, highlight their biotechnological potential and understand the basis of adaptation to low temperature. As of now several psychrophilic and psychrotolerant yeasts from Antarctic soils and marine waters have been characterized with respect to their growth characteristics, ecological distribution and taxonomic significance. Interestingly most of these species belonged to basidiomycetous yeasts which as a group are known for their ability to circumvent and survive under stress conditions. Simultaneously their possible role as work horses in the biotechnological industry was recognized due to their ability to produce novel enzymes and biomolecules such as agents for the breakdown of xenobiotics, and novel pharmaceutical chemi cals. The high activity of psychrophilic enzymes at low and moderate temperatures offers potential economic benefits. As of now lipases from Pseudozyma antarctica have been extensively studied to understand their unique thermal stability at 90°C and also because of its use in the pharmaceutical, agriculture, food, cosmetics and chemical industry. A few of the other enzymes which have been studied include extracellular alpha-amylase and glucoamylase from the yeast Pseudozyma antarctica (Candida antarctica), an extra-cellular protease from Cryptococcus humicola, an aspartyl proteinase from Cryptococcus humicola, a novel extracellular subtilase from Leucosporidium antarcticum, and a xylanase from Cryptococcus adeliensis

  5. Degradation of 5-hydroxymethylfurfural during yeast fermentation.

    PubMed

    Akıllıoglu, Halise Gül; Mogol, Burçe Ataç; Gökmen, Vural

    2011-12-01

    5-Hydroxymethyl furfural (HMF) may occur in malt in high quantities depending on roasting conditions. However, the HMF content of different types of beers is relatively low, indicating its potential for degradation during fermentation. This study investigates the degradation kinetics of HMF in wort during fermentation by Saccharomyces cerevisiae. The results indicated that HMF decreased exponentially as fermentation progressed. The first-order degradation rate of HMF was 0.693 × 10(-2) and 1.397 × 10(-2)min(-1) for wort and sweet wort, respectively, indicating that sugar enhances the activity of yeasts. In wort, HMF was converted into hydroxymethyl furfuryl alcohol by yeasts with a high yield (79-84% conversion). Glucose and fructose were utilised more rapidly by the yeasts in dark roasted malt than in pale malt (p<0.05). The conversion of HMF into hydroxymethyl furfuryl alcohol seems to be a primary activity of yeast cells, and presence of sugars in the fermentation medium increases this activity.

  6. Microfermentation Test For Identification Of Yeast

    NASA Technical Reports Server (NTRS)

    Pierson, D. L.; Mishra, S. K.; Molina, Thomas C.

    1995-01-01

    Microfermentation test developed as supplementary method for use in identifying yeasts, especially in clinical and environmental studies. In comparison with traditional fermentation tests, simpler and easier, and requiries less equipment, material, and laboratory space. Results obtained in days instead of weeks.

  7. Yeast cell differentiation: Lessons from pathogenic and non-pathogenic yeasts.

    PubMed

    Palková, Zdena; Váchová, Libuše

    2016-09-01

    Yeasts, historically considered to be single-cell organisms, are able to activate different differentiation processes. Individual yeast cells can change their life-styles by processes of phenotypic switching such as the switch from yeast-shaped cells to filamentous cells (pseudohyphae or true hyphae) and the transition among opaque, white and gray cell-types. Yeasts can also create organized multicellular structures such as colonies and biofilms, and the latter are often observed as contaminants on surfaces in industry and medical care and are formed during infections of the human body. Multicellular structures are formed mostly of stationary-phase or slow-growing cells that diversify into specific cell subpopulations that have unique metabolic properties and can fulfill specific tasks. In addition to the development of multiple protective mechanisms, processes of metabolic reprogramming that reflect a changed environment help differentiated individual cells and/or community cell constituents to survive harmful environmental attacks and/or to escape the host immune system. This review aims to provide an overview of differentiation processes so far identified in individual yeast cells as well as in multicellular communities of yeast pathogens of the Candida and Cryptococcus spp. and the Candida albicans close relative, Saccharomyces cerevisiae. Molecular mechanisms and extracellular signals potentially involved in differentiation processes are also briefly mentioned.

  8. Preservation of frozen yeast cells by trehalose.

    PubMed

    Diniz-Mendes, L; Bernardes, E; de Araujo, P S; Panek, A D; Paschoalin, V M

    1999-12-05

    Two different methods commonly used to preserve intact yeast cells-freezing and freeze-drying-were compared. Different yeast cells submitted to these treatments were stored for 28 days and cell viability assessed during this period. Intact yeast cells showed to be less tolerant to freeze-drying than to freezing. The rate of survival for both treatments could be enhanced by exogenous trehalose (10%) added during freezing and freeze-drying treatments or by a combination of two procedures: a pre-exposure of cells to 40 degrees C for 60 min and addition of trehalose. A maximum survival level of 71.5 +/- 6.3% after freezing could be achieved at the end of a storage period of 28 days, whereas only 25.0 +/- 1.4% showed the ability to tolerate freeze-drying treatment, if both low-temperature treatments were preceded by a heat exposure and addition of trehalose to yeast cells. Increased survival ability was also obtained when the pre-exposure treatment of yeast cells was performed at 10 degrees C for 3 h and trehalose was added: these treatments enhanced cell survival following freezing from 20.5 +/- 7. 7% to 60.0 +/- 3.5%. Although both mild cold and heat shock treatments could enhance cell tolerance to low temperature, only the heat treatment was able to increase the accumulation of intracellular trehalose whereas, during cold shock exposure, the intracellular amount of trehalose remained unaltered. Intracellular trehalose levels seemed not to be the only factor contributing to cell tolerance against freezing and freeze-drying treatments; however, the protection that this sugar confers to cells can be exerted only if it is to be found on both sides of the plasma membrane.

  9. Biotransformation of hop aroma terpenoids by ale and lager yeasts.

    PubMed

    King, Andrew J; Dickinson, J Richard

    2003-03-01

    Terpenoids are important natural flavour compounds, which are introduced to beer via hopping. It has been shown recently that yeasts are able to biotransform some monoterpene alcohols. As a first step towards examining whether yeasts are capable of altering hop terpenoids during the brewing of beer, we investigated whether they were transformed when an ale and lager yeast were cultured in the presence of a commercially available syrup. Both yeasts transformed the monoterpene alcohols geraniol and linalool. The lager yeast also produced acetate esters of geraniol and citronellol. The major terpenoids of hop oil, however, were not biotransformed. Oxygenated terpenoids persisted much longer than the alkenes.

  10. Evaluation of Fungichrom 1: a new yeast identification system.

    PubMed

    Umabala, P; Satheeshkumar, T; Lakshmi, V

    2002-01-01

    Advances in anti-fungal therapy necessitate the need for accurate identification of fungi especially yeasts to their species level for more effective management. Unlike the time consuming conventional methods of yeast identification using fermentation and assimilation patterns of various carbohydrates, the new commercialized yeast identification systems are simpler, rapid and are particularly easy to interpret. In our study, a new colorimetric yeast identification system-Fungichrom 1(International microbio, Signes, France) was evaluated against the conventional method to identify 50 clinical isolates of yeasts belonging to the genera -Candida, Cryptococcus, Geotrichum. 96% agreement was found between the two methods.

  11. Molecular identification of yeasts associated with traditional Egyptian dairy products.

    PubMed

    El-Sharoud, W M; Belloch, C; Peris, D; Querol, A

    2009-09-01

    This study aimed to examine the diversity and ecology of yeasts associated with traditional Egyptian dairy products employing molecular techniques in yeast identification. A total of 120 samples of fresh and stored Domiati cheese, kariesh cheese, and "Matared" cream were collected from local markets and examined. Forty yeast isolates were cultured from these samples and identified using the restriction-fragment length polymorphism (RFLPs) of 5.8S-ITS rDNA region and sequencing of the domains D1 and D2 of the 26S rRNA gene. Yeasts were identified as Issatchenkia orientalis (13 isolates), Candida albicans (4 isolates), Clavispora lusitaniae (Candida lusitaniae) (9 isolates), Kodamaea ohmeri (Pichia ohmeri) (1 isolate), Kluyveromyces marxianus (6 isolates), and Candida catenulata (7 isolates). With the exception of C. lusitaniae, the D1/D2 26S rRNA gene sequences were 100% identical for the yeast isolates within the same species. Phylogenetic reconstruction of C. lusitaniae isolates grouped them into 3 distinguished clusters. Kariesh cheese was found to be the most diverse in its yeast floras and contained the highest total yeast count compared with other examined dairy products. This was linked to the acidic pH and lower salt content of this cheese, which favor the growth and survival of yeasts in foodstuffs. Stored Domiati cheese also contained diverse yeast species involving isolates of the pathogenic yeast C. albicans. This raises the possibility of dairy products being vehicles of transmission of pathogenic yeasts.

  12. Inventions on baker's yeast strains and specialty ingredients.

    PubMed

    Gélinas, Pierre

    2009-06-01

    Baker's yeast is one of the oldest food microbial starters. Between 1927 and 2008, 165 inventions on more than 337 baker's yeast strains were patented. The first generation of patented yeast strains claimed improved biomass yield at the yeast plant, higher gassing power in dough or better survival to drying to prepare active dry baker's yeast. Especially between 1980 and 1995, a major interest was given to strains for multiple bakery applications such as dough with variable sugar content and stored at refrigeration (cold) or freezing temperatures. During the same period, genetically engineered yeast strains became very popular but did not find applications in the baking industry. Since year 2000, patented baker's yeast strains claimed aroma, anti-moulding or nutritive properties to better meet the needs of the baking industry. In addition to patents on yeast strains, 47 patents were issued on baker's yeast specialty ingredients for niche markets. This review shows that patents on baker's yeast with improved characteristics such as aromatic or nutritive properties have regularly been issued since the 1920's. Overall, it also confirms recent interest for a very wide range of tailored-made yeast-based ingredients for bakery applications.

  13. A caspase-related protease regulates apoptosis in yeast.

    PubMed

    Madeo, Frank; Herker, Eva; Maldener, Corinna; Wissing, Silke; Lächelt, Stephan; Herlan, Mark; Fehr, Markus; Lauber, Kirsten; Sigrist, Stephan J; Wesselborg, Sebastian; Fröhlich, Kai Uwe

    2002-04-01

    Yeast can undergo cell death accompanied by cellular markers of apoptosis. However, orthologs of classical mammalian apoptosis regulators appeared to be missing from the yeast genome, challenging a common mechanism of yeast and mammalian apoptosis. Here we investigate Yor197w, a yeast protein with structural homology to mammalian caspases, and demonstrate caspase-like processing of the protein. Hydrogen peroxide treatment induces apoptosis together with a caspase-like enzymatic activity in yeast. This response is completely abrogated after disruption and strongly stimulated after overexpression of Yor197w. Yor197w also mediates the death process within chronologically aged cultures, pointing to a physiological role in elimination of overaged cells. We conclude that Yor197w indeed functions as a bona fide caspase in yeast and propose the name Yeast Caspase-1 (YCA1, gene YCA1).

  14. Yeast Biodiversity from DOQ Priorat Uninoculated Fermentations

    PubMed Central

    Padilla, Beatriz; García-Fernández, David; González, Beatriz; Izidoro, Iara; Esteve-Zarzoso, Braulio; Beltran, Gemma; Mas, Albert

    2016-01-01

    Climate, soil, and grape varieties are the primary characteristics of terroir and lead to the definition of various appellations of origin. However, the microbiota associated with grapes are also affected by these conditions and can leave a footprint in a wine that will be part of the characteristics of terroir. Thus, a description of the yeast microbiota within a vineyard is of interest not only to provide a better understanding of the winemaking process, but also to understand the source of microorganisms that maintain a microbial footprint in wine from the examined vineyard. In this study, two typical grape varieties, Grenache and Carignan, have been sampled from four different vineyards in the DOQ Priorat winegrowing region. Afterward, eight spontaneous alcoholic fermentations containing only grapes from one sampling point and of one variety were conducted at laboratory scale. The fermentation kinetics and yeast population dynamics within each fermentation experiment were evaluated. Yeast identification was performed by RFLP-PCR of the 5.8S-ITS region and by sequencing D1/D2 of the 26S rRNA gene of the isolates. The fermentation kinetics did not indicate clear differences between the two varieties of grapes or among vineyards. Approximately 1,400 isolates were identified, exhibiting high species richness in some fermentations. Of all the isolates studied, approximately 60% belong to the genus Hanseniaspora, 16% to Saccharomyces, and 11% to Candida. Other minor genera, such as Hansenula, Issatchenkia, Kluyveromyces, Saccharomycodes, and Zygosaccharomyces, were also found. The distribution of the identified yeast throughout the fermentation process was studied, and Saccharomyces cerevisiae was found to be present mainly at the end of the fermentation process, while Aureobasidium pullulans was isolated primarily during the first days of fermentation in three of the eight spontaneous fermentations. This work highlights the complexity and diversity of the vineyard

  15. Misidentification of clinical yeast isolates by using the updated Vitek Yeast Biochemical Card.

    PubMed Central

    Dooley, D P; Beckius, M L; Jeffrey, B S

    1994-01-01

    The Vitek Yeast Biochemical Card (YBC) is widely used as a rapid identification (RI) (within 48 h) system for clinical yeast isolates. We compared the RI results obtained by the YBC technique with matched results obtained with the API 20C system. The RI of germ tube-negative yeasts isolated from 222 clinical specimens was performed with the YBC system, and the results were compared with those of standard identifications obtained by using the API 20C system and morphology, with additional biochemical reactions performed as required. Commonly isolated yeasts (Candida albicans [n = 29], Candida tropicalis [n = 40], Torulopsis [Candida] glabrata [n = 28], Candida parapsilosis [n = 12], and Cryptococcus neoformans [n = 14]) were generally well identified (115 of 123 [93%] identified correctly, with only C. albicans, C. tropicalis, and C. neoformans mis- or unidentified more than once). The RI of less commonly isolated yeasts included in the YBC database, however, was less successful (54 of 99 [55%] correct). The YBC card failed to identify 42% (10 of 24) of Candida krusei isolates, 80% (4 of 5) of Candida lambica isolates, 88% (7 of 8) of Trichosporon beigelii isolates, and 83% (10 of 12) of Cryptococcus isolates (non-C. neoformans species). For most identification failures (79%; 42 of 53) there was no identification by the end of 48 h; the other identification failures (21%; 11 of 53) gave definite but incorrect identifications. Of eight rare clinical yeast isolates not included in the Vitek database, six were correctly, not identified, while two (25%) were falsely assigned a definite RI (one Hansenula fabianii isolate was identified as Rhodotorula glutinis, and one Hansenula isolate [non-Hansenula anomala] was identified as Hansenula anomala). While the Vitek YBC rapidly and adequately identifies common yeast isolates, it fails in the RI of more unusual organisms. PMID:7883873

  16. Yeast as Models of Mitotic Fidelity.

    PubMed

    Torres, Eduardo

    2015-01-01

    Chromosome missegregation leads to aneuploidy which is defined as the cellular state of having a chromosome count that is not an exact multiple of the haploid number. Aneuploidy is associated with human diseases including mental retardation, neurodegenerative diseases and cancer. In addition, aneuploidy is the major cause of spontaneous abortions and its occurrence increases with aging. Therefore, it is important to understand the molecular mechanisms by which cells respond and adapt to aneuploidy. Saccharomyces cerevisiae has proven to be a good model to study the effects aneuploidy elicits on cellular homeostasis and physiology. This chapter focuses on the current understanding of how the yeast S. cerevisiae responds to the acquisition of extra chromosomes and highlights how studies in aneuploid yeasts provide insights onto the effects of aneuploidy in human cells.

  17. A Sampling of the Yeast Proteome

    PubMed Central

    Futcher, B.; Latter, G. I.; Monardo, P.; McLaughlin, C. S.; Garrels, J. I.

    1999-01-01

    In this study, we examined yeast proteins by two-dimensional (2D) gel electrophoresis and gathered quantitative information from about 1,400 spots. We found that there is an enormous range of protein abundance and, for identified spots, a good correlation between protein abundance, mRNA abundance, and codon bias. For each molecule of well-translated mRNA, there were about 4,000 molecules of protein. The relative abundance of proteins was measured in glucose and ethanol media. Protein turnover was examined and found to be insignificant for abundant proteins. Some phosphoproteins were identified. The behavior of proteins in differential centrifugation experiments was examined. Such experiments with 2D gels can give a global view of the yeast proteome. PMID:10523624

  18. Nuclear organisation and RNAi in fission yeast.

    PubMed

    Woolcock, Katrina J; Bühler, Marc

    2013-06-01

    Over the last decade, the fission yeast Schizosaccharomyces pombe has been used extensively for investigating RNA interference (RNAi)-mediated heterochromatin assembly. However, only recently have studies begun to shed light on the 3D organisation of chromatin and the RNAi machinery in the fission yeast nucleus. These studies indicate association of repressive and active chromatin with different regions of the nuclear periphery, similar to other model organisms, and clustering of functionally related genomic features. Unexpectedly, RNAi factors were shown to associate with nuclear pores and were implicated in the regulation of genomic features outside of the well-studied heterochromatic regions. Nuclear organisation is likely to contribute to substrate specificity of the RNAi pathway. However, further studies are required to elucidate the exact mechanisms and functional importance of this nuclear organisation.

  19. Simulation of Yeast Cooperation in 2D.

    PubMed

    Wang, M; Huang, Y; Wu, Z

    2016-03-01

    Evolution of cooperation has been an active research area in evolutionary biology in decades. An important type of cooperation is developed from group selection, when individuals form spatial groups to prevent them from foreign invasions. In this paper, we study the evolution of cooperation in a mixed population of cooperating and cheating yeast strains in 2D with the interactions among the yeast cells restricted to their small neighborhoods. We conduct a computer simulation based on a game theoretic model and show that cooperation is increased when the interactions are spatially restricted, whether the game is of a prisoner's dilemma, snow drifting, or mutual benefit type. We study the evolution of homogeneous groups of cooperators or cheaters and describe the conditions for them to sustain or expand in an opponent population. We show that under certain spatial restrictions, cooperator groups are able to sustain and expand as group sizes become large, while cheater groups fail to expand and keep them from collapse.

  20. A switchable yeast display/secretion system

    PubMed Central

    Van Deventer, James A.; Kelly, Ryan L.; Rajan, Saravanan; Wittrup, K. Dane; Sidhu, Sachdev S.

    2015-01-01

    Display technologies such as yeast and phage display offer powerful alternatives to traditional immunization-based antibody discovery, but require conversion of displayed proteins into soluble form prior to downstream characterization. Here we utilize amber suppression to implement a yeast-based switchable display/secretion system that enables the immediate production of soluble, antibody-like reagents at the end of screening efforts. Model selections in the switchable format remain efficient, and library screening in the switchable format yields renewable sources of affinity reagents exhibiting nanomolar binding affinities. These results confirm that this system provides a seamless link between display-based screening and the production and evaluation of soluble forms of candidate binding proteins. Switchable display/secretion libraries provide a cloning-free, accessible approach to affinity reagent generation. PMID:26333274

  1. A switchable yeast display/secretion system.

    PubMed

    Van Deventer, James A; Kelly, Ryan L; Rajan, Saravanan; Wittrup, K Dane; Sidhu, Sachdev S

    2015-10-01

    Display technologies such as yeast and phage display offer powerful alternatives to traditional immunization-based antibody discovery, but require conversion of displayed proteins into soluble form prior to downstream characterization. Here we utilize amber suppression to implement a yeast-based switchable display/secretion system that enables the immediate production of soluble, antibody-like reagents at the end of screening efforts. Model selections in the switchable format remain efficient, and library screening in the switchable format yields renewable sources of affinity reagents exhibiting nanomolar binding affinities. These results confirm that this system provides a seamless link between display-based screening and the production and evaluation of soluble forms of candidate binding proteins. Switchable display/secretion libraries provide a cloning-free, accessible approach to affinity reagent generation.

  2. Synchronization of the Budding Yeast Saccharomyces cerevisiae.

    PubMed

    Foltman, Magdalena; Molist, Iago; Sanchez-Diaz, Alberto

    2016-01-01

    A number of model organisms have provided the basis for our understanding of the eukaryotic cell cycle. These model organisms are generally much easier to manipulate than mammalian cells and as such provide amenable tools for extensive genetic and biochemical analysis. One of the most common model organisms used to study the cell cycle is the budding yeast Saccharomyces cerevisiae. This model provides the ability to synchronise cells efficiently at different stages of the cell cycle, which in turn opens up the possibility for extensive and detailed study of mechanisms regulating the eukaryotic cell cycle. Here, we describe methods in which budding yeast cells are arrested at a particular phase of the cell cycle and then released from the block, permitting the study of molecular mechanisms that drive the progression through the cell cycle.

  3. Rolling adhesion kinematics of yeast engineered to express selectins.

    PubMed

    Bhatia, Sujata K; Swers, Jeffrey S; Camphausen, Raymond T; Wittrup, K Dane; Hammer, Daniel A

    2003-01-01

    Selectins are cell adhesion molecules that mediate capture of leukocytes on vascular endothelium as an essential component of the inflammatory response. Here we describe a method for yeast surface display of selectins, together with a functional assay that measures rolling adhesion of selectin-expressing yeast on a ligand-coated surface. E-selectin-expressing yeast roll specifically on surfaces bearing sialyl-Lewis-x ligands. Observation of yeast rolling dynamics at various stages of their life cycle indicates that the kinematics of yeast motion depends on the ratio of the bud radius to the parent radius (B/P). Large-budded yeast "walk" across the surface, alternately pivoting about bud and parent. Small-budded yeast "wobble" across the surface, with bud pivoting about parent. Tracking the bud location of budding yeast allows measurement of the angular velocity of the yeast particle. Comparison of translational and angular velocities of budding yeast demonstrates that selectin-expressing cells are rolling rather than slipping across ligand-coated surfaces.

  4. Biotechnology of non-Saccharomyces yeasts-the basidiomycetes.

    PubMed

    Johnson, Eric A

    2013-09-01

    Yeasts are the major producer of biotechnology products worldwide, exceeding production in capacity and economic revenues of other groups of industrial microorganisms. Yeasts have wide-ranging fundamental and industrial importance in scientific, food, medical, and agricultural disciplines (Fig. 1). Saccharomyces is the most important genus of yeast from fundamental and applied perspectives and has been expansively studied. Non-Saccharomyces yeasts (non-conventional yeasts) including members of the Ascomycetes and Basidiomycetes also have substantial current utility and potential applicability in biotechnology. In an earlier mini-review, "Biotechnology of non-Saccharomyces yeasts-the ascomycetes" (Johnson Appl Microb Biotechnol 97: 503-517, 2013), the extensive biotechnological utility and potential of ascomycetous yeasts are described. Ascomycetous yeasts are particularly important in food and ethanol formation, production of single-cell protein, feeds and fodder, heterologous production of proteins and enzymes, and as model and fundamental organisms for the delineation of genes and their function in mammalian and human metabolism and disease processes. In contrast, the roles of basidiomycetous yeasts in biotechnology have mainly been evaluated only in the past few decades and compared to the ascomycetous yeasts and currently have limited industrial utility. From a biotechnology perspective, the basidiomycetous yeasts are known mainly for the production of enzymes used in pharmaceutical and chemical synthesis, for production of certain classes of primary and secondary metabolites such as terpenoids and carotenoids, for aerobic catabolism of complex carbon sources, and for bioremediation of environmental pollutants and xenotoxicants. Notwithstanding, the basidiomycetous yeasts appear to have considerable potential in biotechnology owing to their catabolic utilities, formation of enzymes acting on recalcitrant substrates, and through the production of unique primary

  5. Identification of Protein Components of Yeast Telomerase

    DTIC Science & Technology

    2000-09-01

    for forming telomeres at sites with stretches of telomere- like DNA. The pifl mutants also exhibit increased loss and decreased recombination of...like DNA. The pifl mutants also exhibit increased loss 6 and decreased recombination of mitochondrial DNA and thus have a high fraction of...the fission yeast Schizosaccharomyces pombe that was predicted to encode a 805 amino acid protein. The S. pombe gene was called rphl+ (RRM3/PIF1

  6. Multipurpose Transposon-Insertion Libraries in Yeast.

    PubMed

    Kumar, Anuj

    2016-06-01

    Libraries of transposon-insertion alleles constitute powerful and versatile tools for large-scale analysis of yeast gene function. Transposon-insertion libraries are constructed most simply through mutagenesis of a plasmid-based genomic DNA library; modification of the mutagenizing transposon by incorporation of yeast selectable markers, recombination sites, and an epitope tag enables the application of insertion alleles for phenotypic screening and protein localization. In particular, yeast genomic DNA libraries have been mutagenized with modified bacterial transposons carrying the URA3 marker, lox recombination sites, and sequence encoding multiple copies of the hemagglutinin (HA) epitope. Mutagenesis with these transposons has yielded a large resource of insertion alleles affecting nearly 4000 yeast genes in total. Through well-established protocols, these insertion libraries can be introduced into the desired strain backgrounds and the resulting insertional mutants can be screened or systematically analyzed. Relative to alternative methods of UV irradiation or chemical mutagenesis, transposon-insertion alleles can be easily identified by PCR-based approaches or high-throughput sequencing. Transposon-insertion libraries also provide a cost-effective alternative to targeted deletion approaches, although, in contrast to start-codon to stop-codon deletions, insertion alleles might not represent true null-mutants. For protein-localization studies, transposon-insertion alleles can provide encoded epitope tags in-frame with internal codons; in many cases, these transposon-encoded epitope tags can provide a more accurate localization for proteins in which terminal sequences are crucial for intracellular targeting. Thus, overall, transposon-insertion libraries can be used quickly and economically and have a particular utility in screening for desired phenotypes and localization patterns in nonstandard genetic backgrounds.

  7. An Engineered Yeast Efficiently Secreting Penicillin

    PubMed Central

    Gidijala, Loknath; Kiel, Jan A. K. W.; Douma, Rutger D.; Seifar, Reza M.; van Gulik, Walter M.; Bovenberg, Roel A. L.; Veenhuis, Marten; van der Klei, Ida J.

    2009-01-01

    This study aimed at developing an alternative host for the production of penicillin (PEN). As yet, the industrial production of this β-lactam antibiotic is confined to the filamentous fungus Penicillium chrysogenum. As such, the yeast Hansenula polymorpha, a recognized producer of pharmaceuticals, represents an attractive alternative. Introduction of the P. chrysogenum gene encoding the non-ribosomal peptide synthetase (NRPS) δ-(L-α-aminoadipyl)-L-cysteinyl-D-valine synthetase (ACVS) in H. polymorpha, resulted in the production of active ACVS enzyme, when co-expressed with the Bacillus subtilis sfp gene encoding a phosphopantetheinyl transferase that activated ACVS. This represents the first example of the functional expression of a non-ribosomal peptide synthetase in yeast. Co-expression with the P. chrysogenum genes encoding the cytosolic enzyme isopenicillin N synthase as well as the two peroxisomal enzymes isopenicillin N acyl transferase (IAT) and phenylacetyl CoA ligase (PCL) resulted in production of biologically active PEN, which was efficiently secreted. The amount of secreted PEN was similar to that produced by the original P. chrysogenum NRRL1951 strain (approx. 1 mg/L). PEN production was decreased over two-fold in a yeast strain lacking peroxisomes, indicating that the peroxisomal localization of IAT and PCL is important for efficient PEN production. The breakthroughs of this work enable exploration of new yeast-based cell factories for the production of (novel) β-lactam antibiotics as well as other natural and semi-synthetic peptides (e.g. immunosuppressive and cytostatic agents), whose production involves NRPS's. PMID:20016817

  8. Structures of yeast vesicle trafficking proteins.

    PubMed Central

    Tishgarten, T.; Yin, F. F.; Faucher, K. M.; Dluhy, R. A.; Grant, T. R.; Fischer von Mollard, G.; Stevens, T. H.; Lipscomb, L. A.

    1999-01-01

    In protein transport between organelles, interactions of v- and t-SNARE proteins are required for fusion of protein-containing vesicles with appropriate target compartments. Mammalian SNARE proteins have been observed to interact with NSF and SNAP, and yeast SNAREs with yeast homologues of NSF and SNAP proteins. This observation led to the hypothesis that, despite low sequence homology, SNARE proteins are structurally similar among eukaryotes. SNARE proteins can be classified into two groups depending on whether they interact with SNARE binding partners via conserved glutamine (Q-SNAREs) or arginine (R-SNAREs). Much of the published structural data available is for SNAREs involved in exocytosis (either in yeast or synaptic vesicles). This paper describes circular dichroism, Fourier transform infrared spectroscopy, and dynamic light scattering data for a set of yeast v- and t-SNARE proteins, Vti1p and Pep12p, that are Q-SNAREs involved in intracellular trafficking. Our results suggest that the secondary structure of Vti1p is highly alpha-helical and that Vti1p forms multimers under a variety of solution conditions. In these respects, Vti1p appears to be distinct from R-SNARE proteins characterized previously. The alpha-helicity of Vti1p is similar to that of Q-SNARE proteins characterized previously. Pep12p, a Q-SNARE, is highly alpha-helical. It is distinct from other Q-SNAREs in that it forms dimers under many of the solution conditions tested in our experiments. The results presented in this paper are among the first to suggest heterogeneity in the functioning of SNARE complexes. PMID:10595551

  9. An engineered yeast efficiently secreting penicillin.

    PubMed

    Gidijala, Loknath; Kiel, Jan A K W; Douma, Rutger D; Seifar, Reza M; van Gulik, Walter M; Bovenberg, Roel A L; Veenhuis, Marten; van der Klei, Ida J

    2009-12-15

    This study aimed at developing an alternative host for the production of penicillin (PEN). As yet, the industrial production of this beta-lactam antibiotic is confined to the filamentous fungus Penicillium chrysogenum. As such, the yeast Hansenula polymorpha, a recognized producer of pharmaceuticals, represents an attractive alternative. Introduction of the P. chrysogenum gene encoding the non-ribosomal peptide synthetase (NRPS) delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase (ACVS) in H. polymorpha, resulted in the production of active ACVS enzyme, when co-expressed with the Bacillus subtilis sfp gene encoding a phosphopantetheinyl transferase that activated ACVS. This represents the first example of the functional expression of a non-ribosomal peptide synthetase in yeast. Co-expression with the P. chrysogenum genes encoding the cytosolic enzyme isopenicillin N synthase as well as the two peroxisomal enzymes isopenicillin N acyl transferase (IAT) and phenylacetyl CoA ligase (PCL) resulted in production of biologically active PEN, which was efficiently secreted. The amount of secreted PEN was similar to that produced by the original P. chrysogenum NRRL1951 strain (approx. 1 mg/L). PEN production was decreased over two-fold in a yeast strain lacking peroxisomes, indicating that the peroxisomal localization of IAT and PCL is important for efficient PEN production. The breakthroughs of this work enable exploration of new yeast-based cell factories for the production of (novel) beta-lactam antibiotics as well as other natural and semi-synthetic peptides (e.g. immunosuppressive and cytostatic agents), whose production involves NRPS's.

  10. Engineered yeast for enhanced CO2 mineralization.

    PubMed

    Barbero, Roberto; Carnelli, Lino; Simon, Anna; Kao, Albert; Monforte, Alessandra d'Arminio; Riccò, Moreno; Bianchi, Daniele; Belcher, Angela

    2013-02-01

    In this work, a biologically catalyzed CO2 mineralization process for the capture of CO2 from point sources was designed, constructed at a laboratory scale, and, using standard chemical process scale-up protocols, was modeled and evaluated at an industrial scale. A yeast display system in Saccharomyces cerevisae was used to screen several carbonic anhydrase isoforms and mineralization peptides for their impact on CO2 hydration, CaCO3 mineralization, and particle settling rate. Enhanced rates for each of these steps in the CaCO3 mineralization process were confirmed using quantitative techniques in lab-scale measurements. The effect of these enhanced rates on the CO2 capture cost in an industrial scale CO2 mineralization process using coal fly ash as the CaO source was evaluated. The model predicts a process using bCA2- yeast and fly ash is ~10% more cost effective per ton of CO2 captured than a process with no biological molecules, a savings not realized by wild-type yeast and high-temperature stable recombinant CA2 alone or in combination. The levelized cost of electricity for a power plant using this process was calculated and scenarios in which this process compares favorably to CO2 capture by MEA absorption process are presented.

  11. SNF1/AMPK pathways in yeast

    PubMed Central

    Hedbacker, Kristina; Carlson, Marian

    2009-01-01

    The SNF1/AMPK family of protein kinases is highly conserved in eukaryotes and is required for energy homeostasis in mammals, plants, and fungi. SNF1 protein kinase was initially identified by genetic analysis in the budding yeast Saccharomyces cerevisiae. SNF1 is required primarily for the adaptation of yeast cells to glucose limitation and for growth on carbon sources that are less preferred than glucose, but is also involved in responses to other environmental stresses. SNF1 regulates transcription of a large set of genes, modifies the activity of metabolic enzymes, and controls various nutrient-responsive cellular developmental processes. Like AMPK, SNF1 protein kinase is heterotrimeric. It is phosphorylated and activated by the upstream kinases Sak1, Tos3, and Elm1 and is inactivated by the Reg1-Glc7 protein phosphatase 1. Further regulation of SNF1 is achieved through autoinhibition and through control of its subcellular localization. Here we review the current understanding of SNF1 protein kinase pathways in Saccharomyces cerevisiae and other yeasts. PMID:17981722

  12. Engineered yeast for enhanced CO2 mineralization†

    PubMed Central

    Barbero, Roberto; Carnelli, Lino; Simon, Anna; Kao, Albert; Monforte, Alessandra d’Arminio; Riccò, Moreno; Bianchi, Daniele; Belcher, Angela

    2014-01-01

    In this work, a biologically catalyzed CO2 mineralization process for the capture of CO2 from point sources was designed, constructed at a laboratory scale, and, using standard chemical process scale-up protocols, was modeled and evaluated at an industrial scale. A yeast display system in Saccharomyces cerevisae was used to screen several carbonic anhydrase isoforms and mineralization peptides for their impact on CO2 hydration, CaCO3 mineralization, and particle settling rate. Enhanced rates for each of these steps in the CaCO3 mineralization process were confirmed using quantitative techniques in lab-scale measurements. The effect of these enhanced rates on the CO2 capture cost in an industrial scale CO2 mineralization process using coal fly ash as the CaO source was evaluated. The model predicts a process using bCA2- yeast and fly ash is ~10% more cost effective per ton of CO2 captured than a process with no biological molecules, a savings not realized by wild-type yeast and high-temperature stable recombinant CA2 alone or in combination. The levelized cost of electricity for a power plant using this process was calculated and scenarios in which this process compares favorably to CO2 capture by MEA absorption process are presented. PMID:25289021

  13. Comparative genomics of biotechnologically important yeasts

    PubMed Central

    Riley, Robert; Haridas, Sajeet; Wolfe, Kenneth H.; Lopes, Mariana R.; Hittinger, Chris Todd; Göker, Markus; Salamov, Asaf A.; Wisecaver, Jennifer H.; Long, Tanya M.; Aerts, Andrea L.; Barry, Kerrie W.; Choi, Cindy; Clum, Alicia; Coughlan, Aisling Y.; Deshpande, Shweta; Douglass, Alexander P.; Hanson, Sara J.; Klenk, Hans-Peter; LaButti, Kurt M.; Lapidus, Alla; Lindquist, Erika A.; Lipzen, Anna M.; Meier-Kolthoff, Jan P.; Ohm, Robin A.; Otillar, Robert P.; Pangilinan, Jasmyn L.; Peng, Yi; Rosa, Carlos A.; Scheuner, Carmen; Sibirny, Andriy A.; Slot, Jason C.; Stielow, J. Benjamin; Sun, Hui; Kurtzman, Cletus P.; Blackwell, Meredith; Grigoriev, Igor V.

    2016-01-01

    Ascomycete yeasts are metabolically diverse, with great potential for biotechnology. Here, we report the comparative genome analysis of 29 taxonomically and biotechnologically important yeasts, including 16 newly sequenced. We identify a genetic code change, CUG-Ala, in Pachysolen tannophilus in the clade sister to the known CUG-Ser clade. Our well-resolved yeast phylogeny shows that some traits, such as methylotrophy, are restricted to single clades, whereas others, such as l-rhamnose utilization, have patchy phylogenetic distributions. Gene clusters, with variable organization and distribution, encode many pathways of interest. Genomics can predict some biochemical traits precisely, but the genomic basis of others, such as xylose utilization, remains unresolved. Our data also provide insight into early evolution of ascomycetes. We document the loss of H3K9me2/3 heterochromatin, the origin of ascomycete mating-type switching, and panascomycete synteny at the MAT locus. These data and analyses will facilitate the engineering of efficient biosynthetic and degradative pathways and gateways for genomic manipulation. PMID:27535936

  14. Strategies for identifying new prions in yeast.

    PubMed

    MacLea, Kyle S; Ross, Eric D

    2011-01-01

    The unexpected discovery of two prions, [URE3] and [PSI+], in Saccharomyces cerevisiae led to questions about how many other proteins could undergo similar prion-based structural conversions. However, [URE3] and [PSI+] were discovered by serendipity in genetic screens. Cataloging the full range of prions in yeast or in other organisms will therefore require more systematic search methods. Taking advantage of some of the unique features of prions, various researchers have developed bioinformatic and experimental methods for identifying novel prion proteins. These methods have generated long lists of prion candidates. The systematic testing of some of these prion candidates has led to notable successes; however, even in yeast, where rapid growth rate and ease of genetic manipulation aid in testing for prion activity, such candidate testing is laborious. Development of better methods to winnow the field of prion candidates will greatly aid in the discovery of new prions, both in yeast and in other organisms, and help us to better understand the role of prions in biology.

  15. How to build a yeast nucleus.

    PubMed

    Wong, Hua; Arbona, Jean-Michel; Zimmer, Christophe

    2013-01-01

    Biological functions including gene expression and DNA repair are affected by the 3D architecture of the genome, but the underlying mechanisms are still unknown. Notably, it remains unclear to what extent nuclear architecture is driven by generic physical properties of polymers or by specific factors such as proteins binding particular DNA sequences. The budding yeast nucleus has been intensely studied by imaging and biochemical techniques, resulting in a large quantitative data set on locus positions and DNA contact frequencies. We recently described a quantitative model of the interphase yeast nucleus in which chromosomes are represented as passively moving polymer chains. This model ignores the DNA sequence information except for specific constraints at the centromeres, telomeres, and the ribosomal DNA (rDNA). Despite its simplicity, the model accounts for a large majority of experimental data, including absolute and relative locus positions and contact frequency patterns at chromosomal and subchromosomal scales. Here, we also illustrate the model's ability to reproduce observed features of chromatin movements. Our results strongly suggest that the dynamic large-scale architecture of the yeast nucleus is dominated by statistical properties of randomly moving polymers with a few sequence-specific constraints, rather than by a large number of DNA-specific factors or epigenetic modifications. In addition, we show that our model accounts for recently measured variations in homologous recombination efficiency, illustrating its potential for quantitatively understanding functional consequences of nuclear architecture.

  16. Ribosome Biogenesis in the Yeast Saccharomyces cerevisiae

    PubMed Central

    Woolford, John L.; Baserga, Susan J.

    2013-01-01

    Ribosomes are highly conserved ribonucleoprotein nanomachines that translate information in the genome to create the proteome in all cells. In yeast these complex particles contain four RNAs (>5400 nucleotides) and 79 different proteins. During the past 25 years, studies in yeast have led the way to understanding how these molecules are assembled into ribosomes in vivo. Assembly begins with transcription of ribosomal RNA in the nucleolus, where the RNA then undergoes complex pathways of folding, coupled with nucleotide modification, removal of spacer sequences, and binding to ribosomal proteins. More than 200 assembly factors and 76 small nucleolar RNAs transiently associate with assembling ribosomes, to enable their accurate and efficient construction. Following export of preribosomes from the nucleus to the cytoplasm, they undergo final stages of maturation before entering the pool of functioning ribosomes. Elaborate mechanisms exist to monitor the formation of correct structural and functional neighborhoods within ribosomes and to destroy preribosomes that fail to assemble properly. Studies of yeast ribosome biogenesis provide useful models for ribosomopathies, diseases in humans that result from failure to properly assemble ribosomes. PMID:24190922

  17. How do yeast sense mitochondrial dysfunction?

    PubMed Central

    Knorre, Dmitry A.; Sokolov, Svyatoslav S.; Zyrina, Anna N.; Severin, Fedor F.

    2016-01-01

    Apart from energy transformation, mitochondria play important signaling roles. In yeast, mitochondrial signaling relies on several molecular cascades. However, it is not clear how a cell detects a particular mitochondrial malfunction. The problem is that there are many possible manifestations of mitochondrial dysfunction. For example, exposure to the specific antibiotics can either decrease (inhibitors of respiratory chain) or increase (inhibitors of ATP-synthase) mitochondrial transmembrane potential. Moreover, even in the absence of the dysfunctions, a cell needs feedback from mitochondria to coordinate mitochondrial biogenesis and/or removal by mitophagy during the division cycle. To cope with the complexity, only a limited set of compounds is monitored by yeast cells to estimate mitochondrial functionality. The known examples of such compounds are ATP, reactive oxygen species, intermediates of amino acids synthesis, short peptides, Fe-S clusters and heme, and also the precursor proteins which fail to be imported by mitochondria. On one hand, the levels of these molecules depend not only on mitochondria. On the other hand, these substances are recognized by the cytosolic sensors which transmit the signals to the nucleus leading to general, as opposed to mitochondria-specific, transcriptional response. Therefore, we argue that both ways of mitochondria-to-nucleus communication in yeast are mostly (if not completely) unspecific, are mediated by the cytosolic signaling machinery and strongly depend on cellular metabolic state. PMID:28357322

  18. Wood impregnation of yeast lees for winemaking.

    PubMed

    Palomero, Felipe; Bertani, Paolo; Fernández de Simón, Brígida; Cadahía, Estrella; Benito, Santiago; Morata, Antonio; Suárez-Lepe, José A

    2015-03-15

    This study develops a new method to produce more complex wines by means of an indirect diffusion of wood aromas from yeast cell-walls. An exogenous lyophilized biomass was macerated with an ethanol wood extract solution and subsequently dried. Different times were used for the adsorption of polyphenols and volatile compounds to the yeast cell-walls. The analysis of polyphenols and volatile compounds (by HPLC/DAD and GC-MS, respectively) demonstrate that the adsorption/diffusion of these compounds from the wood to the yeast takes place. Red wines were also aged with Saccharomyces cerevisiae lees that had been impregnated with wood aromas and subsequently dried. Four different types of wood were used: chestnut, cherry, acacia and oak. Large differences were observed between the woods studied with regards to their volatile and polyphenolic profiles. Sensory evaluations confirmed large differences even with short-term contact between the wines and the lees, showing that the method could be of interest for red wine making. In addition, the results demonstrate the potential of using woods other than oak in cooperage.

  19. Yeasts found in vineyards and wineries.

    PubMed

    Varela, Cristian; Borneman, Anthony R

    2017-03-01

    Wine is a complex beverage, comprising thousands of metabolites that are produced through the action of a plethora of yeasts and bacteria during fermentation of grape must. These microbial communities originate in the vineyard and the winery and reflect the influence of several factors including grape variety, geographical location, climate, vineyard spraying, technological practices, processing stage and season (pre-harvest, harvest, post-harvest). Vineyard and winery microbial communities have the potential to participate during fermentation and influence wine flavour and aroma. Therefore, there is an enormous interest in isolating and characterising these communities, particularly non-Saccharomyces yeast species to increase wine flavour diversity, while also exploting regional signature microbial populations to enhance regionality. In this review we describe the role and relevance of the main non-Saccharomyces yeast species found in vineyards and wineries. This includes the latest reports covering the application of these species for winemaking; and the biotechnological characteristics and potential applications of non-Saccharomyces species in other areas. In particular, we focus attention on the species for which molecular and genomic tools and resources are available for study. Copyright © 2016 John Wiley & Sons, Ltd.

  20. In situ rheology of yeast biofilms.

    PubMed

    Brugnoni, Lorena I; Tarifa, María C; Lozano, Jorge E; Genovese, Diego

    2014-01-01

    The aim of the present work was to investigate the in situ rheological behavior of yeast biofilms growing on stainless steel under static and turbulent flow. The species used (Rhodototula mucilaginosa, Candida krusei, Candida kefyr and Candida tropicalis) were isolated from a clarified apple juice industry. The flow conditions impacted biofilm composition over time, with a predominance of C. krusei under static and turbulent flow. Likewise, structural variations occurred, with a tighter appearance under dynamic flow. Under turbulent flow there was an increase of 112 μm in biofilm thickness at 11 weeks (p < 0.001) and cell morphology was governed by hyphal structures and rounded cells. Using the in situ growth method introduced here, yeast biofilms were determined to be viscoelastic materials with a predominantly solid-like behavior, and neither this nor the G'0 values were significantly affected by the flow conditions or the growth time, and at large deformations their weak structure collapsed beyond a critical strain of about 1.5-5%. The present work could represent a starting point for developing in situ measurements of yeast rheology and contribute to a thin body of knowledge about fungal biofilm formation.

  1. Yeast Exocytic v-SNAREs Confer Endocytosis

    PubMed Central

    Gurunathan, Sangiliyandi; Chapman-Shimshoni, Daphne; Trajkovic, Selena; Gerst, Jeffrey E.

    2000-01-01

    In yeast, homologues of the synaptobrevin/VAMP family of v-SNAREs (Snc1 and Snc2) confer the docking and fusion of secretory vesicles at the cell surface. As no v-SNARE has been shown to confer endocytosis, we examined whether yeast lacking the SNC genes, or possessing a temperature-sensitive allele of SNC1 (SNC1ala43), are deficient in the endocytic uptake of components from the cell surface. We found that both SNC and temperature-shifted SNC1ala43 yeast are deficient in their ability to deliver the soluble dye FM4–64 to the vacuole. Under conditions in which vesicles accumulate, FM4–64 stained primarily the cytoplasm as well as fragmented vacuoles. In addition, α-factor–stimulated endocytosis of the α-factor receptor, Ste2, was fully blocked, as evidenced using a Ste2-green fluorescent protein fusion protein as well as metabolic labeling studies. This suggests a direct role for Snc v-SNAREs in the retrieval of membrane proteins from the cell surface. Moreover, this idea is supported by genetic and physical data that demonstrate functional interactions with t-SNAREs that confer endosomal transport (e.g., Tlg1,2). Notably, Snc1ala43 was found to be nonfunctional in cells lacking Tlg1 or Tlg2. Thus, we propose that synaptobrevin/VAMP family members are engaged in anterograde and retrograde protein sorting steps between the Golgi and the plasma membrane. PMID:11029060

  2. [Mitochondria inheritance in yeast saccharomyces cerevisiae].

    PubMed

    Fizikova, A Iu

    2011-01-01

    The review is devoted to the main mechanisms of mitochondria inheritance in yeast Saccharonmyces cerevisiae. The genetic mechanisms of functionally active mitochondria inheritance in eukaryotic cells is one of the most relevant in modem researches. A great number of genetic diseases are associated with mitochondria dysfunction. Plasticity of eukaryotic cell metabolism according to the environmental changes is ensured by adequate mitochondria functioning by means of ATP synthesis coordination, reactive oxygen species accumulation, apoptosis regulation and is an important factor of cell adaptation to stress. Mitochondria participation in important for cell vitality processes masters the presence of accurate mechanisms of mitochondria functions regulation according to environment fluctuations. The mechanisms of mitochondria division and distribution are highly conserved. Baker yeast S. cerevisiae is an ideal model object for mitochondria researches due to energetic metabolism lability, ability to switch over respiration to fermentation, and petite-positive phenotype. Correction of metabolism according to the environmental changes is necessary for cell vitality. The influence of respiratory, carbon, amino acid and phosphate metabolism on mitochondria functions was shown. As far as the mechanisms that stabilize functions of mitochondria and mtDNA are highly conserve, we can project yeast regularities on higher eukaryotes systems. This makes it possible to approximate understanding the etiology and pathogenesis of a great number of human diseases.

  3. On the Modeling of Endocytosis in Yeast

    PubMed Central

    Zhang, Tao; Sknepnek, Rastko; Bowick, M.J.; Schwarz, J.M.

    2015-01-01

    The cell membrane deforms during endocytosis to surround extracellular material and draw it into the cell. Results of experiments on endocytosis in yeast show general agreement that 1) actin polymerizes into a network of filaments exerting active forces on the membrane to deform it, and 2) the large-scale membrane deformation is tubular in shape. In contrast, there are three competing proposals for precisely how the actin filament network organizes itself to drive the deformation. We use variational approaches and numerical simulations to address this competition by analyzing a meso-scale model of actin-mediated endocytosis in yeast. The meso-scale model breaks up the invagination process into three stages: 1) initiation, where clathrin interacts with the membrane via adaptor proteins; 2) elongation, where the membrane is then further deformed by polymerizing actin filaments; and 3) pinch-off. Our results suggest that the pinch-off mechanism may be assisted by a pearling-like instability. We rule out two of the three competing proposals for the organization of the actin filament network during the elongation stage. These two proposals could be important in the pinch-off stage, however, where additional actin polymerization helps break off the vesicle. Implications and comparisons with earlier modeling of endocytosis in yeast are discussed. PMID:25650919

  4. Evaluation of the VITEK 2 System for Rapid Identification of Yeasts and Yeast-Like Organisms

    PubMed Central

    Graf, Barbara; Adam, Thomas; Zill, Edith; Göbel, Ulf B.

    2000-01-01

    The new VITEK 2 system is a fully automated system dedicated to the identification and susceptibility testing of microorganisms. In conjunction with the VITEK ID-YST card the VITEK 2 system allows the identification of clinically important yeasts and yeast-like organisms in 15 h due to a sensitive fluorescence-based technology. The ID-YST card consists of 47 biochemical reactions. The database comprises 51 taxa, including newly described species. In this study we evaluated the reliability of the VITEK ID-YST card for the identification of yeasts and yeast-like organisms encountered in a clinical microbiology laboratory. A total of 241 strains representing 21 species were studied. The strains were isolated from clinical samples within a period of 60 days prior to the identification. The tests were performed using 24-h to 55-h subcultures on Sabouraud-gentamicin-chloramphenicol agar. Each strain was tested in parallel using the ID 32C strip as a comparison method combined with microscopic morphology and an agglutination test for C. krusei. Overall, 222 strains (92.1%) were unequivocally identified including 11 isolates (4.6%) identified with low discrimination resolved by simple additional tests. Ten strains (4.1%) for which results were given with low discrimination could not be unequivocally identified with supplemental tests, 4 strains (1.7%) were misidentified and 5 strains (2.1%) could not be identified. In conclusion, we found that the VITEK 2 system is a rapid and accurate method for the identification of medically important yeasts and yeast-like organisms. PMID:10790099

  5. Not your ordinary yeast: non-Saccharomyces yeasts in wine production uncovered.

    PubMed

    Jolly, Neil P; Varela, Cristian; Pretorius, Isak S

    2014-03-01

    Saccharomyces cerevisiae and grape juice are 'natural companions' and make a happy wine marriage. However, this relationship can be enriched by allowing 'wild' non-Saccharomyces yeast to participate in a sequential manner in the early phases of grape must fermentation. However, such a triangular relationship is complex and can only be taken to 'the next level' if there are no spoilage yeast present and if the 'wine yeast' - S. cerevisiae - is able to exert its dominance in time to successfully complete the alcoholic fermentation. Winemakers apply various 'matchmaking' strategies (e.g. cellar hygiene, pH, SO2 , temperature and nutrient management) to keep 'spoilers' (e.g. Dekkera bruxellensis) at bay, and allow 'compatible' wild yeast (e.g. Torulaspora delbrueckii, Pichia kluyveri, Lachancea thermotolerans and Candida/Metschnikowia pulcherrima) to harmonize with potent S. cerevisiae wine yeast and bring the best out in wine. Mismatching can lead to a 'two is company, three is a crowd' scenario. More than 40 of the 1500 known yeast species have been isolated from grape must. In this article, we review the specific flavour-active characteristics of those non-Saccharomyces species that might play a positive role in both spontaneous and inoculated wine ferments. We seek to present 'single-species' and 'multi-species' ferments in a new light and a new context, and we raise important questions about the direction of mixed-fermentation research to address market trends regarding so-called 'natural' wines. This review also highlights that, despite the fact that most frontier research and technological developments are often focussed primarily on S. cerevisiae, non-Saccharomyces research can benefit from the techniques and knowledge developed by research on the former.

  6. Cell surface engineering of yeast for applications in white biotechnology.

    PubMed

    Kuroda, Kouichi; Ueda, Mitsuyoshi

    2011-01-01

    Cell surface engineering is a promising strategy for the molecular breeding of whole-cell biocatalysts. By using this strategy, yeasts can be constructed by the cell surface display of functional proteins; these yeasts are referred to as arming yeasts. Because reactions using arming yeasts as whole-cell biocatalysts occur on the cell surface, materials that cannot enter the cell can be used as reaction substrates. Numerous arming yeasts have therefore been constructed for a wide range of uses such as biofuel production, synthesis of valuable chemicals, adsorption or degradation of environmental pollutants, recovery of rare metal ions, and biosensors. Here, we review the science of yeast cell surface modification as well as current applications and future opportunities.

  7. Genetic aspects of targeted insertion mutagenesis in yeasts.

    PubMed

    Klinner, U; Schäfer, B

    2004-05-01

    Targeted insertion mutagenesis is a main molecular tool of yeast science initially applied in Saccharomyces cerevisiae. The method was extended to fission yeast Schizosaccharomyces pombe and to "non-conventional" yeast species, which show specific properties of special interest to both basic and applied research. Consequently, the behaviour of such non-Saccharomyces yeasts is reviewed against the background of the knowledge of targeted insertion mutagenesis in S. cerevisiae. Data of homologous integration efficiencies obtained with circular, ends-in or ends-out vectors in several yeasts are compared. We follow details of targeted insertion mutagenesis in order to recognize possible rate-limiting steps. The route of the vector to the target and possible mechanisms of its integration into chromosomal genes are considered. Specific features of some yeast species are discussed. In addition, similar approaches based on homologous recombination that have been established for the mitochondrial genome of S. cerevisiae are described.

  8. Isolation and characterization of ethanol tolerant yeast strains

    PubMed Central

    Tikka, Chiranjeevi; Osuru, Hari Prasad; Atluri, Navya; Raghavulu, Praveen Chakravarthi Veera; yellapu, Nanda Kumar; Mannur, Ismail Shaik; Prasad, Uppu Venkateswara; Aluru, Sudheer; K, Narasimha Varma; Bhaskar, Matcha

    2013-01-01

    Yeast strains are commonly associated with sugar rich environments. Various fruit samples were selected as source for isolating yeast cells. The isolated cultures were identified at Genus level by colony morphology, biochemical characteristics and cell morphological characters. An attempt has been made to check the viability of yeast cells under different concentrations of ethanol. Ethanol tolerance of each strain was studied by allowing the yeast to grow in liquid YEPD (Yeast Extract Peptone Dextrose) medium having different concentrations of ethanol. A total of fifteen yeast strains isolated from different samples were used for the study. Seven strains of Saccharomyces cerevisiae obtained from different fruit sources were screened for ethanol tolerance. The results obtained in this study show a range of tolerance levels between 7%-12% in all the stains. Further, the cluster analysis based on 22 RAPD (Random Amplified polymorphic DNA) bands revealed polymorphisms in these seven Saccharomyces strains. PMID:23750092

  9. Yeast Genomics for Bread, Beer, Biology, Bucks and Breath

    NASA Astrophysics Data System (ADS)

    Sakharkar, Kishore R.; Sakharkar, Meena K.

    The rapid advances and scale up of projects in DNA sequencing dur ing the past two decades have produced complete genome sequences of several eukaryotic species. The versatile genetic malleability of the yeast, and the high degree of conservation between its cellular processes and those of human cells have made it a model of choice for pioneering research in molecular and cell biology. The complete sequence of yeast genome has proven to be extremely useful as a reference towards the sequences of human and for providing systems to explore key gene functions. Yeast has been a ‘legendary model’ for new technologies and gaining new biological insights into basic biological sciences and biotechnology. This chapter describes the awesome power of yeast genetics, genomics and proteomics in understanding of biological function. The applications of yeast as a screening tool to the field of drug discovery and development are highlighted and the traditional importance of yeast for bakers and brewers is discussed.

  10. 21 CFR 172.381 - Vitamin D2 bakers yeast.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Vitamin D2 bakers yeast. 172.381 Section 172.381... CONSUMPTION Special Dietary and Nutritional Additives § 172.381 Vitamin D2 bakers yeast. Vitamin D2 bakers yeast may be used safely in foods as a source of vitamin D2 and as a leavening agent in accordance...

  11. 21 CFR 172.381 - Vitamin D2 bakers yeast.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Vitamin D2 bakers yeast. 172.381 Section 172.381... Additives § 172.381 Vitamin D2 bakers yeast. Vitamin D2 bakers yeast may be used safely in foods as a source of vitamin D2 and as a leavening agent in accordance with the following prescribed conditions:...

  12. [Novel bioconversion systems using a yeast molecular display system].

    PubMed

    Shibasaki, Seiji

    2010-11-01

    The budding yeast Saccharomyces cerevisiae has been used for the process of fermentation as well as for studies in biochemistry and molecular biology as a eukaryotic model cell or tool for the analysis of gene functions. Thus, yeast is essential in industries and researches. Yeast cells have a cell wall, which is one characteristic that helps distinguish yeast cells from other eukaryotic cells such as mammalian cells. We have developed a molecular display system using the protein of the yeast cell wall as an anchor for foreign proteins. Yeast cells have been designed for use in sensing and metal adsorption, and have been used in vaccines and for screening novel proteins. Currently, yeast is used not only as a tool for analyzing gene or protein function but also in molecular display technology. The phage display system, which is at the forefront of molecular display technologies, is a powerful tool for screening ligands bound to a target molecule and for analyzing protein-protein interactions; however, in some cases, eukaryotic proteins are not easily expressed by this system. On the other hand, yeast cells have the ability to express eukaryotic proteins and proliferate; thus, these cells display various proteins. Yeast cells are more appropriate for white biotechnology. In this review, displays of enzymes that are important in bioconversion, such as lipases and β-glucosidases, are going to be introduced.

  13. Ethanol production from xylose by enzymic isomerization and yeast fermentation

    SciTech Connect

    Chiang, L.C.; Hsiao, H.Y.; Ueng, P.P.; Chen, L.F.; Tsao, G.T.

    1981-01-01

    Repetitive enzymic isomerization of xylose followed by yeast fermentation of xylulose, and simultaneous enzymic isomerization and yeast fermentation were proven to be methods capable of converting xylose to ethanol. The fermentation product, ethanol, xylitol, or glycerol, has little inhibitory or deactivation effect on the activity of isomerase. In a comparison of the ability of yeasts to ferment xylulose to ethanol, Schizosaccharomyces pombe was found to be superior to industrial bakers' yeast. Under optimal conditions (pH 6, temperature 30/sup 0/C), a final ethanol concentration of 6.3 wt.% was obtained from simulated hemicellulose hydrolysate using a simultaneous fermentation process. The ethanol yield was over 80% of the theoretical value.

  14. Identification of yeasts present in sour fermented foods and fodders.

    PubMed

    Middelhoven, Wouter J

    2002-07-01

    This paper deals with rapid methods for identification of 50 yeast species frequently isolated from foods and fodders that underwent a lactic acid fermentation. However, many yeast species present in olive brine, alpechin, and other olive products were not treated. The methods required for identification include light microscopy, physiological growth tests (ID32C system of BioMérieux), assimilation of nitrate and of ethylamine as sole nitrogen sources, vitamin requirement, and maximum growth temperature. An identification key to treated yeast species is provided. In another table characteristics of all yeast species treated are listed.

  15. Evolution and variation of the yeast (Saccharomyces) genome.

    PubMed

    Mortimer, R K

    2000-04-01

    In this review we describe the role of the yeast Saccharomyces in the development of human societies including the use of this organism in the making of wine, bread, beer, and distilled beverages. We also discuss the tremendous diversity of yeast found in natural (i.e., noninoculated) wine fermentations and the scientific uses of yeast over the past 60 years. In conclusion, we present ideas on the model of "genome renewal" and the use of this model to explain the mode by which yeast has evolved and how diversity can be generated.

  16. Media for preservative resistant yeasts: a collaborative study.

    PubMed

    Hocking, A D

    1996-04-01

    An international collaborative study was carried out to determine the most effective medium for selective isolation and enumeration of preservative resistant yeasts. Such a medium should prevent the growth of other yeasts such as Saccharomyces cerevisiae that are tolerant to lower levels of commonly used food preservatives, and sensitive yeasts such as Rhodotorula species. The study compared two non-selective media that are in common use for cultivation of yeasts from foods, Malt Extract agar (MEA) and Tryptone Glucose Yeast extract agar (TGY) with media made selective for preservative resistant yeasts by addition of 0.5% acetic acid to these two basal media (MEAA and TGYA). A fifth medium, Zygosaccharomyces bailii medium (ZBM) was also included in the study. These media were compared for their efficacy in selective isolation and enumeration of the preservative resistant yeasts Zygosaccharomyces bailii, Schizosaccharomyces pombe and Pichia membranaefaciens. MEA and TGY without acetic acid were used as control, non-selective media, and Rhodotorula glutinis was the preservative sensitive control culture. Seven laboratories in six countries took part in the study. Of the non-selective media, TGY generally gave the highest counts, and TGY amended with 0.5% acetic acid (TGYA) was the best medium for recovery of all three preservative-resistant yeasts. ZBM was found to be selective for Z. bailii, but counts of this yeast on ZBM were significantly lower than on TGYA. R. glutinis did not grow on any of the selective media.

  17. Effect of fungicides on epiphytic yeasts associated with strawberry

    PubMed Central

    Debode, Jane; Van Hemelrijck, Wendy; Creemers, Piet; Maes, Martine

    2013-01-01

    We studied the effect of two commonly used fungicides on the epiphytic yeast community of strawberry. Greenhouse and field experiments were conducted applying Switch (cyprodinil plus fludioxonil) or Signum (boscalid plus pyraclostrobin) to strawberry plants. Yeasts on leaves and fruits were assessed on treated and untreated plants at several time points via plating and denaturing gradient gel electrophoresis (DGGE) analysis. The yeast counts on plates of the treated plants were similar to the control plants. Unripe fruits had 10 times larger yeast concentrations than ripe fruits or leaves. Some dominant yeast types were isolated and in vitro tests showed that they were at least 10 times less sensitive to Switch and Signum as compared with two important fungal strawberry pathogens Botrytis cinerea and Colletotrichum acutatum, which are the targets for the fungicide control. DGGE analysis showed that the applied fungicides had no effect on the composition of the yeast communities, while the growing system, strawberry tissue, and sampling time did affect the yeast communities. The yeast species most commonly identified were Cryptococcus, Rhodotorula, and Sporobolomyces. These results point toward the potential applicability of natural occurring yeast antagonists into an integrated disease control strategy for strawberry diseases.

  18. A Photometer for Measuring Population Growth in Yeast.

    ERIC Educational Resources Information Center

    Tatina, Robert; Hartley, Tamela; Thomas, Danita

    1999-01-01

    Describes the construction and use of an inexpensive, portable photometer designed specifically for estimating population sizes in yeast cultures. Suggests activities for use with the photometer. (WRM)

  19. Yeast and Mammalian Metallothioneins Functionally Substitute for Yeast Copper-Zinc Superoxide Dismutase

    NASA Astrophysics Data System (ADS)

    Tamai, Katherine T.; Gralla, Edith B.; Ellerby, Lisa M.; Valentine, Joan S.; Thiele, Dennis J.

    1993-09-01

    Copper-zinc superoxide dismutase catalyzes the disproportionation of superoxide anion to hydrogen peroxide and dioxygen and is thought to play an important role in protecting cells from oxygen toxicity. Saccharomyces cerevisiae strains lacking copper-zinc superoxide dismutase, which is encoded by the SOD1 gene, are sensitive to oxidative stress and exhibit a variety of growth defects including hypersensitivity to dioxygen and to superoxide-generating drugs such as paraquat. We have found that in addition to these known phenotypes, SOD1-deletion strains fail to grow on agar containing the respiratory carbon source lactate. We demonstrate here that expression of the yeast or monkey metallothionein proteins in the presence of copper suppresses the lactate growth defect and some other phenotypes associated with SOD1-deletion strains, indicating that copper metallothioneins substitute for copper-zinc superoxide dismutase in vivo to protect cells from oxygen toxicity. Consistent with these results, we show that yeast metallothionein mRNA levels are dramatically elevated under conditions of oxidative stress. Furthermore, in vitro assays demonstrate that yeast metallothionein, purified or from whole-cell extracts, exhibits copper-dependent antioxidant activity. Taken together, these data suggest that both yeast and mammalian metallothioneins may play a direct role in the cellular defense against oxidative stress by functioning as antioxidants.

  20. Genetically modified yeast species and fermentation processes using genetically modified yeast

    DOEpatents

    Rajgarhia, Vineet; Koivuranta, Kari; Penttila, Merja; Ilmen, Marja; Suominen, Pirkko; Aristidou, Aristos; Miller, Christopher Kenneth; Olson, Stacey; Ruohonen, Laura

    2011-05-17

    Yeast cells are transformed with an exogenous xylose isomerase gene. Additional genetic modifications enhance the ability of the transformed cells to ferment xylose to ethanol or other desired fermentation products. Those modifications', include deletion of non-specific or specific aldose reductase gene(s), deletion of xylitol dehydrogenase gene(s) and/or overexpression of xylulokinase.

  1. Genetically modified yeast species, and fermentation processes using genetically modified yeast

    SciTech Connect

    Rajgarhia, Vineet; Koivuranta, Kari; Penttila, Merja; Ilmen, Marja; Suominen, Pirkko; Aristidou, Aristos; Miller, Christopher Kenneth; Olson, Stacey; Ruohonen, Laura

    2014-01-07

    Yeast cells are transformed with an exogenous xylose isomerase gene. Additional genetic modifications enhance the ability of the transformed cells to ferment xylose to ethanol or other desired fermentation products. Those modifications include deletion of non-specific aldose reductase gene(s), deletion of xylitol dehydrogenase gene(s) and/or overexpression of xylulokinase.

  2. Genetically modified yeast species, and fermentation processes using genetically modified yeast

    SciTech Connect

    Rajgarhia, Vineet; Koivuranta, Kari; Penttila, Merja; Ilmen, Marja; Suominen, Pirkko; Aristidou, Aristos; Miller, Christopher Kenneth; Olson, Stacey; Ruohonen, Laura

    2013-05-14

    Yeast cells are transformed with an exogenous xylose isomerase gene. Additional genetic modifications enhance the ability of the transformed cells to ferment xylose to ethanol or other desired fermentation products. Those modifications include deletion of non-specific or specific aldose reductase gene(s), deletion of xylitol dehydrogenase gene(s) and/or overexpression of xylulokinase.

  3. Genetically modified yeast species, and fermentation processes using genetically modified yeast

    SciTech Connect

    Rajgarhia, Vineet; Koivuranta, Kari; Penttila, Merja; Ilmen, Marja; Suominen, Pirkko; Aristidou, Aristos; Miller, Christopher Kenneth; Olson, Stacey; Ruohonen, Laura

    2016-08-09

    Yeast cells are transformed with an exogenous xylose isomerase gene. Additional genetic modifications enhance the ability of the transformed cells to ferment xylose to ethanol or other desired fermentation products. Those modifications include deletion of non-specific or specific aldose reductase gene(s), deletion of xylitol dehydrogenase gene(s) and/or overexpression of xylulokinase.

  4. Studying Functions of All Yeast Genes Simultaneously

    NASA Technical Reports Server (NTRS)

    Stolc, Viktor; Eason, Robert G.; Poumand, Nader; Herman, Zelek S.; Davis, Ronald W.; Anthony Kevin; Jejelowo, Olufisayo

    2006-01-01

    A method of studying the functions of all the genes of a given species of microorganism simultaneously has been developed in experiments on Saccharomyces cerevisiae (commonly known as baker's or brewer's yeast). It is already known that many yeast genes perform functions similar to those of corresponding human genes; therefore, by facilitating understanding of yeast genes, the method may ultimately also contribute to the knowledge needed to treat some diseases in humans. Because of the complexity of the method and the highly specialized nature of the underlying knowledge, it is possible to give only a brief and sketchy summary here. The method involves the use of unique synthetic deoxyribonucleic acid (DNA) sequences that are denoted as DNA bar codes because of their utility as molecular labels. The method also involves the disruption of gene functions through deletion of genes. Saccharomyces cerevisiae is a particularly powerful experimental system in that multiple deletion strains easily can be pooled for parallel growth assays. Individual deletion strains recently have been created for 5,918 open reading frames, representing nearly all of the estimated 6,000 genetic loci of Saccharomyces cerevisiae. Tagging of each deletion strain with one or two unique 20-nucleotide sequences enables identification of genes affected by specific growth conditions, without prior knowledge of gene functions. Hybridization of bar-code DNA to oligonucleotide arrays can be used to measure the growth rate of each strain over several cell-division generations. The growth rate thus measured serves as an index of the fitness of the strain.

  5. Crystal structure of yeast Sco1

    SciTech Connect

    Abajian, Carnie; Rosenzweig, Amy C.

    2010-03-05

    The Sco family of proteins are involved in the assembly of the dinuclear CuA site in cytochrome c oxidase (COX), the terminal enzyme in aerobic respiration. These proteins, which are found in both eukaryotes and prokaryotes, are characterized by a conserved CXXXC sequence motif that binds copper ions and that has also been proposed to perform a thiol:disulfide oxidoreductase function. The crystal structures of Saccharomyces cerevisiae apo Sco1 (apo-ySco1) and Sco1 in the presence of copper ions (Cu-ySco1) were determined to 1.8- and 2.3-{angstrom} resolutions, respectively. Yeast Sco1 exhibits a thioredoxin-like fold, similar to that observed for human Sco1 and a homolog from Bacillus subtilis. The Cu-ySco1 structure, obtained by soaking apo-ySco1 crystals in copper ions, reveals an unexpected copper-binding site involving Cys181 and Cys216, cysteine residues present in ySco1 but not in other homologs. The conserved CXXXC cysteines, Cys148 and Cys152, can undergo redox chemistry in the crystal. An essential histidine residue, His239, is located on a highly flexible loop, denoted the Sco loop, and can adopt positions proximal to both pairs of cysteines. Interactions between ySco1 and its partner proteins yeast Cox17 and yeast COX2 are likely to occur via complementary electrostatic surfaces. This high-resolution model of a eukaryotic Sco protein provides new insight into Sco copper binding and function.

  6. Navigating yeast genome maintenance with functional genomics.

    PubMed

    Measday, Vivien; Stirling, Peter C

    2016-03-01

    Maintenance of genome integrity is a fundamental requirement of all organisms. To address this, organisms have evolved extremely faithful modes of replication, DNA repair and chromosome segregation to combat the deleterious effects of an unstable genome. Nonetheless, a small amount of genome instability is the driver of evolutionary change and adaptation, and thus a low level of instability is permitted in populations. While defects in genome maintenance almost invariably reduce fitness in the short term, they can create an environment where beneficial mutations are more likely to occur. The importance of this fact is clearest in the development of human cancer, where genome instability is a well-established enabling characteristic of carcinogenesis. This raises the crucial question: what are the cellular pathways that promote genome maintenance and what are their mechanisms? Work in model organisms, in particular the yeast Saccharomyces cerevisiae, has provided the global foundations of genome maintenance mechanisms in eukaryotes. The development of pioneering genomic tools inS. cerevisiae, such as the systematic creation of mutants in all nonessential and essential genes, has enabled whole-genome approaches to identifying genes with roles in genome maintenance. Here, we review the extensive whole-genome approaches taken in yeast, with an emphasis on functional genomic screens, to understand the genetic basis of genome instability, highlighting a range of genetic and cytological screening modalities. By revealing the biological pathways and processes regulating genome integrity, these analyses contribute to the systems-level map of the yeast cell and inform studies of human disease, especially cancer.

  7. Detection and identification of wild yeasts in lager breweries.

    PubMed

    van der Aa Kühle, A; Jespersen, L

    1998-09-08

    Wild yeasts were detected in 41 out of 101 brewery yeast samples investigated using six different selective principles. Malt extract, yeast extract, glucose, peptone (MYGP) agar supplemented with 195 ppm CuSO4 was found to be the most effective selective principle, detecting wild yeasts in 80% of the contaminated samples. Both Saccharomyces and non-Saccharomyces wild yeasts were detected on this medium. Lysine medium, crystal violet medium and incubation of non-selective media at 37 degrees C detected wild yeasts in 46-56% of the contaminated samples. On using actidione medium, only 20% of the wild yeasts were detected. The combined use of MYGP supplemented with 195 ppm CuSO4 and one of the other selective principles did not improve the recovery of the wild yeasts. The wild yeasts found consisted of Saccharomyces cerevisiae (57%), Pichia spp. (28%) and Candida spp. (15%). Using the API ID 32 C kit, 35 different assimilation profiles were obtained for the 124 wild yeast isolates investigated. All isolates were capable of glucose assimilation, whereas only 79% of the isolates assimilated saccharose, 75% maltose, 70% galactose, 65% raffinose and 65% lactate. Lactose, inositol, rhamnose and glucuronate were not assimilated by any of the isolates. The differences in assimilation pattern did not reflect any differences in recovery by the selective principles investigated. The majority of the wild yeast isolates investigated were capable of growth in wort and beer, indicating their possible role as spoilage organisms. The Sacch. cerevisiae isolates were found to be the most hazardous, with some isolates being capable of extensive growth in bottled beer within seventeen days at ambient temperature.

  8. Inheritance of the fittest mitochondria in yeast

    PubMed Central

    Vevea, Jason D.; Swayne, Theresa C.; Boldogh, Istvan R.; Pon, Liza A.

    2013-01-01

    Eukaryotic cells compartmentalize their biochemical processes within organelles, which have specific functions that must be maintained for overall cellular health. As the site of aerobic energy mobilization and essential biosynthetic activities, mitochondria are critical for cell survival and proliferation. Here, we describe mechanisms to control the quality and quantity of mitochondria within cells with an emphasis on findings from the budding yeast, Saccharomyces cerevisiae. We also describe how mitochondrial quality and quantity control systems that operate during cell division affect lifespan and cell cycle progression. PMID:23932848

  9. Exo-β-glucanases in yeast

    PubMed Central

    Abd-El-Al, Ahmed T. H.; Phaff, H. J.

    1968-01-01

    1. A number of yeast species were examined for the presence of β-glucanases. Extracts obtained by cell disruption of Saccharomyces cerevisiae, Fabospora fragilis and Hansenula anomala hydrolysed laminarin and pustulan with the production of glucose. Enzymic activities were also detected in the culture fluids of F. fragilis and H. anomala grown aerobically in buffered mineral medium with glucose as the carbon source. 2. F. fragilis and H. anomala possessed approximately sevenfold higher β-(1→3)-glucanase activity than S. cerevisiae. 3. Intracellular exo-β-glucanase from baker's yeast was purified 344-fold from the dialysed cell extract. 4. Exo-β-glucanase from F. fragilis was purified 114-fold from the dialysed culture fluid and 423-fold from the dialysed intracellular extract. The purified extracellular and intracellular enzymes had similar properties and essentially the same specific activity, 79 enzyme units/mg. of protein. 5. Extracellular exo-β-glucanase of H. anomala was purified 600-fold. 6. The optimum pH of the enzymes from F. fragilis, S. cerevisiae and H. anomala was 5·5 in each case. Chromatographic evidence indicated that the three enzymes remove glucosyl units sequentially from laminarin as well as pustulan. 7. The ratio of activities towards laminarin and pustulan remained constant during purification of the exo-β-glucanase obtained from the three species, suggesting a single enzyme. Additional evidence for its unienzymic nature are: (i) the two activities were destroyed at exactly the same rate on heating of the purified enzyme from F. fragilis at three different temperatures; (ii) the competitive inhibitor glucono-δ-lactone gave the same value of Ki when tested with either substrate; (iii) quantitative application of the `mixed-substrate' method with the purified enzyme of S. cerevisiae gave data that were in excellent agreement with those calculated on the assumption of a single enzyme. 8. The purified exo-β-glucanases of the different

  10. Alcohol from glucose without using yeast

    SciTech Connect

    Not Available

    1980-12-17

    Researchers at the Oak Ridge National Laboratory (Oak Ridge, Tenn.) have demonstrated a continuous way to make ethanol by bacterial fermentation of glucose using the bacterium Zymomonas mobilis. The bacterium has several advantages over yeasts and can be maintained at higher cell densities in immobilized-cell reactors. Nevertheless, even the most ethanol-tolerant strains of Zymomonas can't survive a concentration greater than 15%, and further studies are required before the bacterium can be used in large-scale alcohol- from-biomass schemes.

  11. Inheritance of the fittest mitochondria in yeast.

    PubMed

    Vevea, Jason D; Swayne, Theresa C; Boldogh, Istvan R; Pon, Liza A

    2014-01-01

    Eukaryotic cells compartmentalize their biochemical processes within organelles, which have specific functions that must be maintained for overall cellular health. As the site of aerobic energy mobilization and essential biosynthetic activities, mitochondria are critical for cell survival and proliferation. Here, we describe mechanisms to control the quality and quantity of mitochondria within cells with an emphasis on findings from the budding yeast Saccharomyces cerevisiae. We also describe how mitochondrial quality and quantity control systems that operate during cell division affect lifespan and cell cycle progression.

  12. De Novo Biosynthesis of Vanillin in Fission Yeast (Schizosaccharomyces pombe) and Baker's Yeast (Saccharomyces cerevisiae) ▿

    PubMed Central

    Hansen, Esben H.; Møller, Birger Lindberg; Kock, Gertrud R.; Bünner, Camilla M.; Kristensen, Charlotte; Jensen, Ole R.; Okkels, Finn T.; Olsen, Carl E.; Motawia, Mohammed S.; Hansen, Jørgen

    2009-01-01

    Vanillin is one of the world's most important flavor compounds, with a global market of 180 million dollars. Natural vanillin is derived from the cured seed pods of the vanilla orchid (Vanilla planifolia), but most of the world's vanillin is synthesized from petrochemicals or wood pulp lignins. We have established a true de novo biosynthetic pathway for vanillin production from glucose in Schizosaccharomyces pombe, also known as fission yeast or African beer yeast, as well as in baker's yeast, Saccharomyces cerevisiae. Productivities were 65 and 45 mg/liter, after introduction of three and four heterologous genes, respectively. The engineered pathways involve incorporation of 3-dehydroshikimate dehydratase from the dung mold Podospora pauciseta, an aromatic carboxylic acid reductase (ACAR) from a bacterium of the Nocardia genus, and an O-methyltransferase from Homo sapiens. In S. cerevisiae, the ACAR enzyme required activation by phosphopantetheinylation, and this was achieved by coexpression of a Corynebacterium glutamicum phosphopantetheinyl transferase. Prevention of reduction of vanillin to vanillyl alcohol was achieved by knockout of the host alcohol dehydrogenase ADH6. In S. pombe, the biosynthesis was further improved by introduction of an Arabidopsis thaliana family 1 UDP-glycosyltransferase, converting vanillin into vanillin β-d-glucoside, which is not toxic to the yeast cells and thus may be accumulated in larger amounts. These de novo pathways represent the first examples of one-cell microbial generation of these valuable compounds from glucose. S. pombe yeast has not previously been metabolically engineered to produce any valuable, industrially scalable, white biotech commodity. PMID:19286778

  13. Identification of superior lipid producing Lipomyces and Myxozyma yeasts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oleaginous yeasts are of interest for production of single cell oils from sugars. Here 17 members of the Lipomyces and Myxozyma clade were screened for lipid production when cultured on glucose. The highest ranking yeasts included L. tetrasporus (21 g/l), L. kononenkoae (19.6 g/l), and L. lipofer (1...

  14. Investigating the proteins released by yeasts in synthetic wine fermentations.

    PubMed

    Mostert, Talitha T; Divol, Benoit

    2014-02-03

    Proteins from various biological sources previously identified in wine play important roles in the functioning and survival of their producers and may exhibit oenological properties. Yeasts contribute significantly to the protein pool during and after alcoholic fermentation. While the extracellular proteins of Saccharomyces cerevisiae, the main wine yeast species, have been characterised, those of non-Saccharomyces yeasts remain restricted to a few enzymes. A more comprehensive insight into all proteins released during fermentation could improve our understanding of how yeasts survive and interact in mixed culture fermentations. This study aimed to characterise the exo-proteome of Saccharomyces and selected non-Saccharomyces yeasts in pure and mixed cultures in a wine-like medium. While S. cerevisiae completed the fermentation rapidly, Metschnikowia pulcherrima hardly fermented and Lachancea thermotolerans fermented slowly but steadily. In sequential fermentations, the kinetics resembled those of the non-Saccharomyces yeasts for a period before switching to that of S. cerevisiae. Identification of the proteins present in wine at the end of fermentation using mass fingerprinting revealed the large diversity of proteins secreted and the influence of yeast interactions therein. The fermentation kinetics observed could partially be explained by the extent of the contribution of the different yeast to the protein content.

  15. Dielectric modelling of cell division for budding and fission yeast

    NASA Astrophysics Data System (ADS)

    Asami, Koji; Sekine, Katsuhisa

    2007-02-01

    The frequency dependence of complex permittivity or the dielectric spectrum of a system including a cell in cell division has been simulated by a numerical technique based on the three-dimensional finite difference method. Two different types of cell division characteristic of budding and fission yeast were examined. The yeast cells are both regarded as a body of rotation, and thus have anisotropic polarization, i.e. the effective permittivity of the cell depends on the orientation of the cell to the direction of an applied electric field. In the perpendicular orientation, where the rotational axis of the cell is perpendicular to the electric field direction, the dielectric spectra for both yeast cells included one dielectric relaxation and its intensity depended on the cell volume. In the parallel orientation, on the other hand, two dielectric relaxations appeared with bud growth for budding yeast and with septum formation for fission yeast. The low-frequency relaxation was shifted to a lower frequency region by narrowing the neck between the bud and the mother cell for budding yeast and by increasing the degree of septum formation for fission yeast. After cell separation, the low-frequency relaxation disappeared. The simulations well interpreted the oscillation of the relative permittivity of culture broth found for synchronous cell growth of budding yeast.

  16. Exploring the Ubiquitin-Proteasome Protein Degradation Pathway in Yeast

    ERIC Educational Resources Information Center

    Will, Tamara J.; McWatters, Melissa K.; McQuade, Kristi L.

    2006-01-01

    This article describes an undergraduate biochemistry laboratory investigating the ubiquitin-proteasome pathway in yeast. In this exercise, the enzyme beta-galactosidase (beta-gal) is expressed in yeast under the control of a stress response promoter. Following exposure to heat stress to induce beta-gal expression, cycloheximide is added to halt…

  17. [Yeasts in domestic animals: species identification and susceptibility to antifungals].

    PubMed

    Hamal, Petr; Koukalová, Dagmar

    2010-02-01

    Yeasts frequently colonize various kinds of domestic animals, but may also cause serious diseases. The aim of this study was to identify yeast isolates collected from dogs, cows and pigs, and to determine their in vitro antifungal susceptibility. Fifty-six yeast isolates from dogs (n = 24), cows (n = 20), and pigs (n = 12) were investigated. Appearance of colonies grown on Sabouraud agar, micromorphology on rice agar, as well as assimilation and fermentation of various carbon and nitrogen sources were evaluated. Susceptibility to six antifungals (flucytosine, amphotericin B, miconazole, ketoconazole, itraconazole and fluconazole) was determined semiquantitatively using the commercially available Fungitest kit (Bio-Rad Laboratories). Ten yeast species were identified in dogs with relatively even distribution. On the other hand, cow and pig were clearly dominated by Candida krusei (from 7 species) and Candida rugosa (from 5 species), respectively. Further, most of yeast isolates exhibited good susceptibility to the antifungals tested particularly to amphotericin B, ketoconazole and itraconazole. Based on results, it can be concluded that significant differences in the species spectrum and distribution were documented between groups of yeasts from dogs, cows and pigs. This is probably due to different environmental conditions and the endogenous origin of the yeast isolates. Mostly good susceptibility to systemic antifungals should positively influence the therapy of diseases caused by yeasts in veterinary medicine.

  18. The yeast flora of the coast redwood, Sequoia sempervirens.

    PubMed

    Middelhoven, W J

    2003-01-01

    Only four yeast species could be isolated from young and perannual shoots of the coast redwood tree, Sequoia sempervirens, and from soil beneath the trees, viz. both varieties of Debaryomyces hansenii, Trichosporon pullulans, T. porosum and an unidentified red basidiomycetous yeast.

  19. The making of biodiversity across the yeast subphyllum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Goals for this research project are to determine how the functional diversity of the yeast subphylum is encoded, and to reconstruct the history of yeasts to elucidate the tempo and mode of functional diversification. The impact of this work will be to integrate discoveries within broadly disseminate...

  20. Emergence of Blastoschizomyces capitatus Yeast Infections, Central Europe

    PubMed Central

    Bertschy, Sonja; Aebersold, Franziska; Mueller, Nicolas J.; Achermann, Yvonne; Muehlethaler, Konrad; Zimmerli, Stefan

    2012-01-01

    We report 5 cases of disseminated infection caused by Blastoschizomyces capitatus yeast in central Switzerland. The emergence of this yeast in an area in which it is not known to be endemic should alert clinicians caring for immunocompromised patients outside the Mediterranean region to consider infections caused by unfamiliar fungal pathogens. PMID:22261201

  1. Analysis of the RNA Content of the Yeast "Saccharomyces Cerevisiae"

    ERIC Educational Resources Information Center

    Deutch, Charles E.; Marshall, Pamela A.

    2008-01-01

    In this article, the authors describe an interconnected set of relatively simple laboratory experiments in which students determine the RNA content of yeast cells and use agarose gel electrophoresis to separate and analyze the major species of cellular RNA. This set of experiments focuses on RNAs from the yeast "Saccharomyces cerevisiae", a…

  2. Using Microsatellites to Identify Yeast Strains in Beer

    PubMed Central

    Bruke, Alexandria; Van Brocklin, Jennifer; Rivest, Jason; Prenni, Jessica E.; Ibrahim, Hend

    2012-01-01

    Yeast is an integral part of the brewing process and is responsible for much of the taste and characteristics of beer. During the brewing process, yeast is subject to ageing and stress factors that can result in growth inhibition, decreased genetic stability, and changes in cell membrane stability. Characterization of yeast species used in industrial fermentation (e.g. S. cerevisiae) is of great importance to the brewing industry. The objective of this study was to develop an assay to identify yeast strains commonly used in the production of beer. Six microsatellite regions of DNA (comprised of AAT) were used as sequence tagged site markers (STR) to identify and compare yeast samples and to determine strain within a species. Labeled primers ScATT (1-6) targeting these six microsatellite regions were designed using 6-FAM, VIC, NED and PET 5′-fluorescent labels. The six regions were amplified, in a single reaction, from extracted yeast genomic DNA using a modified multiplex-PCR protocol and the labeled PCR products were analyzed on an ABI 3130xl Genetic Analyzer. Using this approach 6 STR markers were amplified in a single multiplex reaction from a commercially utilized yeast strain provided by Odell Brewing. Different alleles were distinguished based on the size of each STR and the labeling fluorophore. The procedures developed in this study will provide an invaluable tool for the quality control of yeast strains in the brewing industry.

  3. Improving industrial yeast strains: exploiting natural and artificial diversity

    PubMed Central

    Steensels, Jan; Snoek, Tim; Meersman, Esther; Nicolino, Martina Picca; Voordeckers, Karin; Verstrepen, Kevin J

    2014-01-01

    Yeasts have been used for thousands of years to make fermented foods and beverages, such as beer, wine, sake, and bread. However, the choice for a particular yeast strain or species for a specific industrial application is often based on historical, rather than scientific grounds. Moreover, new biotechnological yeast applications, such as the production of second-generation biofuels, confront yeast with environments and challenges that differ from those encountered in traditional food fermentations. Together, this implies that there are interesting opportunities to isolate or generate yeast variants that perform better than the currently used strains. Here, we discuss the different strategies of strain selection and improvement available for both conventional and nonconventional yeasts. Exploiting the existing natural diversity and using techniques such as mutagenesis, protoplast fusion, breeding, genome shuffling and directed evolution to generate artificial diversity, or the use of genetic modification strategies to alter traits in a more targeted way, have led to the selection of superior industrial yeasts. Furthermore, recent technological advances allowed the development of high-throughput techniques, such as ‘global transcription machinery engineering’ (gTME), to induce genetic variation, providing a new source of yeast genetic diversity. PMID:24724938

  4. Specialist nectar-yeasts decline with urbanization in Berlin

    PubMed Central

    Wehner, Jeannine; Mittelbach, Moritz; Rillig, Matthias C.; Verbruggen, Erik

    2017-01-01

    Nectar yeasts are common inhabitants of insect-pollinated flowers but factors determining their distribution are not well understood. We studied the influence of host identity, environmental factors related to pollution/urbanization, and the distance to a target beehive on local distribution of nectar yeasts within Robinia pseudoacacia L. and Tilia tomentosa Moench in Berlin, Germany. Nectar samples of six individuals per species were collected at seven sites in a 2 km radius from each target beehive and plated on YM-Agar to visualise the different morphotypes, which were then identified by sequencing a section of the 26S rDNA gene. Multivariate linear models were used to analyze the effects of all investigated factors on yeast occurrence per tree. Yeast distribution was mainly driven by host identity. The influence of the environmental factors (NO2, height of construction, soil sealing) strongly depended on the radius around the tree, similar to the distance of the sampled beehive. Incidence of specialist nectar-borne yeast species decreased with increasing pollution/urbanization index. Given that specialist yeast species gave way to generalist yeasts that have a reduced dependency on pollinators for between-flower dispersal, our results indicate that increased urbanization may restrict the movement of nectar-specialized yeasts, via limitations of pollinator foraging behavior. PMID:28358006

  5. Overexpression of membrane proteins from higher eukaryotes in yeasts.

    PubMed

    Emmerstorfer, Anita; Wriessnegger, Tamara; Hirz, Melanie; Pichler, Harald

    2014-09-01

    Heterologous expression and characterisation of the membrane proteins of higher eukaryotes is of paramount interest in fundamental and applied research. Due to the rather simple and well-established methods for their genetic modification and cultivation, yeast cells are attractive host systems for recombinant protein production. This review provides an overview on the remarkable progress, and discusses pitfalls, in applying various yeast host strains for high-level expression of eukaryotic membrane proteins. In contrast to the cell lines of higher eukaryotes, yeasts permit efficient library screening methods. Modified yeasts are used as high-throughput screening tools for heterologous membrane protein functions or as benchmark for analysing drug-target relationships, e.g., by using yeasts as sensors. Furthermore, yeasts are powerful hosts for revealing interactions stabilising and/or activating membrane proteins. We also discuss the stress responses of yeasts upon heterologous expression of membrane proteins. Through co-expression of chaperones and/or optimising yeast cultivation and expression strategies, yield-optimised hosts have been created for membrane protein crystallography or efficient whole-cell production of fine chemicals.

  6. An overview of macroautophagy in yeast.

    PubMed

    Wen, Xin; Klionsky, Daniel J

    2016-05-08

    Macroautophagy is an evolutionarily conserved dynamic pathway that functions primarily in a degradative manner. A basal level of macroautophagy occurs constitutively, but this process can be further induced in response to various types of stress including starvation, hypoxia and hormonal stimuli. The general principle behind macroautophagy is that cytoplasmic contents can be sequestered within a transient double-membrane organelle, an autophagosome, which subsequently fuses with a lysosome or vacuole (in mammals, or yeast and plants, respectively), allowing for degradation of the cargo followed by recycling of the resulting macromolecules. Through this basic mechanism, macroautophagy has a critical role in cellular homeostasis; however, either insufficient or excessive macroautophagy can seriously compromise cell physiology, and thus, it needs to be properly regulated. In fact, a wide range of diseases are associated with dysregulation of macroautophagy. There has been substantial progress in understanding the regulation and molecular mechanisms of macroautophagy in different organisms; however, many questions concerning some of the most fundamental aspects of macroautophagy remain unresolved. In this review, we summarize current knowledge about macroautophagy mainly in yeast, including the mechanism of autophagosome biogenesis, the function of the core macroautophagic machinery, the regulation of macroautophagy and the process of cargo recognition in selective macroautophagy, with the goal of providing insights into some of the key unanswered questions in this field.

  7. Yeast lipid metabolism at a glance.

    PubMed

    Klug, Lisa; Daum, Günther

    2014-05-01

    During the last decades, lipids have gained much attention due to their involvement in health and disease. Lipids are required for the formation of membranes and contribute to many different processes such as cell signaling, energy supply, and cell death. Various organelles such as the endoplasmic reticulum, mitochondria, peroxisomes, and lipid droplets are involved in lipid metabolism. The yeast Saccharomyces cerevisiae has become a reliable model organism to study biochemistry, molecular biology, and cell biology of lipids. The availability of mutants bearing defects in lipid metabolic pathways and the ease of manipulation by culture conditions facilitated these investigations. Here, we summarize the current knowledge about lipid metabolism in yeast. We grouped this large topic into three sections dealing with (1) fatty acids; (2) membrane lipids; and (3) storage lipids. Fatty acids serve as building blocks for the synthesis of membrane lipids (phospholipids, sphingolipids) and storage lipids (triacylglycerols, steryl esters). Phospholipids, sterols, and sphingolipids are essential components of cellular membranes. Recent investigations addressing lipid synthesis, degradation, and storage as well as regulatory aspects are presented. The role of enzymes governing important steps of the different lipid metabolic pathways is described. Finally, the link between lipid metabolic and dynamic processes is discussed.

  8. Perchlorate Reduction by Yeast for Mars Exploration

    NASA Technical Reports Server (NTRS)

    Sharma, Alaisha

    2015-01-01

    Martian soil contains high levels (0.6 percentage by mass) of calcium perchlorate (Ca(ClO4)2), which readily dissociates into calcium and the perchlorate ion (ClO4-) in water. Even in trace amounts, perchlorates are toxic to humans and have been implicated in thyroid dysfunction. Devising methods to lessen perchlorate contamination is crucial to minimizing the health risks associated with human exploration and colonization of Mars. We designed a perchlorate reduction pathway, which sequentially reduces perchlorate to chloride (Cl-) and oxygen (O2), for implementation in the yeast Saccharomyces cerevisiae. Using genes obtained from perchlorate reducing bacteria Azospira oryzae and Dechloromonas aromatica, we plan to assemble this pathway directly within S. cerevisiae through recombinational cloning. A perchlorate reduction pathway would enable S. cerevisiae to lower perchlorate levels and produce oxygen, which may be harvested or used directly by S. cerevisiae for aerobic growth and compound synthesis. Moreover, using perchlorate as an external electron acceptor could improve the efficiency of redox-imbalanced production pathways in yeast. Although several perchlorate reducing bacteria have been identified and utilized in water treatment systems on Earth, the widespread use of S. cerevisiae as a synthetic biology platform justifies the development of a perchlorate reducing strain for implementation on Mars.

  9. Nanomechanics of Yeast Surfaces Revealed by AFM

    NASA Astrophysics Data System (ADS)

    Dague, Etienne; Beaussart, Audrey; Alsteens, David

    Despite the large and well-documented characterization of the microbial cell wall in terms of chemical composition, the determination of the mechanical properties of surface molecules in relation to their function remains a key challenge in cell biology.The emergence of powerful tools allowing molecular manipulations has already revolutionized our understanding of the surface properties of fungal cells. At the frontier between nanophysics and molecular biology, atomic force microscopy (AFM), and more specifically single-molecule force spectroscopy (SMFS), has strongly contributed to our current knowledge of the cell wall organization and nanomechanical properties. However, due to the complexity of the technique, measurements on live cells are still at their infancy.In this chapter, we describe the cell wall composition and recapitulate the principles of AFM as well as the main current methodologies used to perform AFM measurements on live cells, including sample immobilization and tip functionalization.The current status of the progress in probing nanomechanics of the yeast surface is illustrated through three recent breakthrough studies. Determination of the cell wall nanostructure and elasticity is presented through two examples: the mechanical response of mannoproteins from brewing yeasts and elasticity measurements on lacking polysaccharide mutant strains. Additionally, an elegant study on force-induced unfolding and clustering of adhesion proteins located at the cell surface is also presented.

  10. Stationary phase in the yeast Saccharomyces cerevisiae.

    PubMed Central

    Werner-Washburne, M; Braun, E; Johnston, G C; Singer, R A

    1993-01-01

    Growth and proliferation of microorganisms such as the yeast Saccharomyces cerevisiae are controlled in part by the availability of nutrients. When proliferating yeast cells exhaust available nutrients, they enter a stationary phase characterized by cell cycle arrest and specific physiological, biochemical, and morphological changes. These changes include thickening of the cell wall, accumulation of reserve carbohydrates, and acquisition of thermotolerance. Recent characterization of mutant cells that are conditionally defective only for the resumption of proliferation from stationary phase provides evidence that stationary phase is a unique developmental state. Strains with mutations affecting entry into and survival during stationary phase have also been isolated, and the mutations have been shown to affect at least seven different cellular processes: (i) signal transduction, (ii) protein synthesis, (iii) protein N-terminal acetylation, (iv) protein turnover, (v) protein secretion, (vi) membrane biosynthesis, and (vii) cell polarity. The exact nature of the relationship between these processes and survival during stationary phase remains to be elucidated. We propose that cell cycle arrest coordinated with the ability to remain viable in the absence of additional nutrients provides a good operational definition of starvation-induced stationary phase. PMID:8393130

  11. Mitochondrial ribosomal proteins (MRPs) of yeast.

    PubMed Central

    Graack, H R; Wittmann-Liebold, B

    1998-01-01

    Mitochondrial ribosomal proteins (MRPs) are the counterparts in that organelle of the cytoplasmic ribosomal proteins in the host. Although the MRPs fulfil similar functions in protein biosynthesis, they are distinct in number, features and primary structures from the latter. Most progress in the eludication of the properties of individual MRPs, and in the characterization of the corresponding genes, has been made in baker's yeast (Saccharomyces cerevisiae). To date, 50 different MRPs have been determined, although biochemical data and mutational analysis propose a total number which is substantially higher. Surprisingly, only a minority of the MRPs that have been characterized show significant sequence similarities to known ribosomal proteins from other sources, thus limiting the deduction of their functions by simple comparison of amino acid sequences. Further, individual MRPs have been characterized functionally by mutational studies, and the regulation of expression of MRP genes has been described. The interaction of the mitochondrial ribosomes with transcription factors specific for individual mitochondrial mRNAs, and the communication between mitochondria and the nucleus for the co-ordinated expression of ribosomal constituents, are other aspects of current MRP research. Although the mitochondrial translational system is still far from being described completely, the yeast MRP system serves as a model for other organisms, including that of humans. PMID:9445368

  12. Divergence of mitotic strategies in fission yeasts

    PubMed Central

    Gu, Ying; Yam, Candice; Oliferenko, Snezhana

    2012-01-01

    The aim of mitosis is to produce two daughter nuclei, each containing a chromosome complement identical to that of the mother nucleus. This can be accomplished through a variety of strategies, with “open” and “closed” modes of mitosis positioned at the opposite ends of the spectrum and a range of intermediate patterns in between. In the “closed” mitosis, the nuclear envelope remains intact throughout the nuclear division. In the “open” division type, the envelope of the original nucleus breaks down early in mitosis and reassembles around the segregated daughter genomes. In any case, the nuclear membrane has to remodel to accommodate the mitotic spindle assembly, chromosome segregation and formation of the daughter nuclei. We have recently shown that within the fission yeast clade, the mitotic control of the nuclear surface area may determine the choice between the nuclear envelope breakdown and a fully “closed” division. Here we discuss our data and argue that comparative cell biology studies using two fission yeast species, Schizosaccharomyces pombe and Schizosaccharomyces japonicus, could provide unprecedented insights into physiology and evolution of mitosis. PMID:22572960

  13. Functional Diversity of Silencers in Budding Yeasts

    PubMed Central

    Sjöstrand, Jimmy O. O.; Kegel, Andreas; Åström, Stefan U.

    2002-01-01

    We studied the silencing of the cryptic mating-type loci HMLα and HMRa in the budding yeast Kluyveromyces lactis. A 102-bp minimal silencer fragment was defined that was both necessary and sufficient for silencing of HMLα. Mutagenesis of the silencer revealed three distinct regions (A, B, and C) that were important for silencing. Recombinant K. lactis ribosomal DNA enhancer binding protein 1 (Reb1p) could bind the silencer in vitro, and point mutations in the B box abolished both Reb1p binding and silencer function. Furthermore, strains carrying temperature-sensitive alleles of the REB1 gene derepressed the transcription of the HMLα1 gene at the nonpermissive temperature. A functional silencer element from the K. lactis cryptic HMRa locus was also identified, which contained both Reb1p binding sites and A boxes, strongly suggesting a general role for these sequences in K. lactis silencing. Our data indicate that different proteins bind to Kluyveromyces silencers than to Saccharomyces silencers. We suggest that the evolution of silencers is rapid in budding yeasts and discuss the similarities and differences between silencers in Saccharomyces and Kluyveromyces. PMID:12456003

  14. Thermodynamic study of yeast phosphoglycerate kinase.

    PubMed

    Hu, C Q; Sturtevant, J M

    1987-01-13

    Enthalpies of binding of MgADP, MgATP, and 3-phosphoglycerate to yeast phosphoglycerate kinase have been determined by flow calorimetry at 9.95-32.00 degrees C. Combination of these data with published dissociation constants [Scopes, R.K. (1978) Eur. J. Biochem. 91, 119-129] yielded the following thermodynamic parameters for the binding of 3-phosphoglycerate at 25 degrees C: delta Go = -6.76 +/- 0.11 kcal mol-1, delta H = 3.74 +/- 0.08 kcal mol-1, delta So = 35.2 +/- 0.6 cal K-1 mol-1, and delta Cp = 0.12 +/- 0.32 kcal K-1 mol-1. The thermal unfolding of phosphoglycerate kinase in the absence and presence of the ligands listed above was studied by differential scanning calorimetry. The temperature of half-completion, t 1/2, of the denaturation and the denaturational enthalpy are increased by the binding of the ligands, the increase in t 1/2 being a manifestation of Le Chatelier's principle and that in enthalpy reflecting the enthalpy of dissociation of the ligand. Only one denaturational peak was observed under all conditions, and in contrast with the case of yeast hexokinase [Takahashi, K., Casey, J.L., & Sturtevant, J.M. (1981) Biochemistry 20, 4693-4697], no definitive evidence for the unfolding of more than one domain was obtained.

  15. Intracellular accumulation of ethanol in yeast

    SciTech Connect

    Loueiro, V.; Ferreira, H.G.

    1983-09-01

    Ethanol produced in the course of a batch fermentation by Saccharomyces cerevisiae or added from the outside, affects adversely the specific rate of growth of the yeast population, its viability, its specific rate of fermentation, and the specific rates of the uptake of sugar and amino acids. The underlying mechanisms are many and include irreversible denaturation and hyperbolic noncompetitive inhibition of glycolytic enzymes, the exponential noncompetitive inhibition of glucose, maltose, and ammonium transport, the depression of the optimum and the maximum temperature for growth, the increase of the minimum temperature for growth, and the enhancement of thermal death and petite mutation. Nagodawithana and Steinkraus reported that added ethanol was less toxic for S. cerevisiae than ethanol produced by the yeast. The death rates were lower in the presence of added ethanol than those measured at similar external ethanol concentrations endogenously produced. They proposed that, due to an unbalance between the rates of production and the net outflux of ethanol, there would be an intracellular accumulation of ethanol which in turn would explain the apparently greater inhibitory potency of endogenously produced ethanol present in the medium. This hypothesis was supported by the findings of several authors who reported that the intracellular concentration of ethanol, in the course of batch fermentation, is much higher than its concentration in the extracellular medium. The present work is an attempt to clarify this matter. (Refs. 32).

  16. Yeast cell factories for fine chemical and API production

    PubMed Central

    Pscheidt, Beate; Glieder, Anton

    2008-01-01

    This review gives an overview of different yeast strains and enzyme classes involved in yeast whole-cell biotransformations. A focus was put on the synthesis of compounds for fine chemical and API (= active pharmaceutical ingredient) production employing single or only few-step enzymatic reactions. Accounting for recent success stories in metabolic engineering, the construction and use of synthetic pathways was also highlighted. Examples from academia and industry and advances in the field of designed yeast strain construction demonstrate the broad significance of yeast whole-cell applications. In addition to Saccharomyces cerevisiae, alternative yeast whole-cell biocatalysts are discussed such as Candida sp., Cryptococcus sp., Geotrichum sp., Issatchenkia sp., Kloeckera sp., Kluyveromyces sp., Pichia sp. (including Hansenula polymorpha = P. angusta), Rhodotorula sp., Rhodosporidium sp., alternative Saccharomyces sp., Schizosaccharomyces pombe, Torulopsis sp., Trichosporon sp., Trigonopsis variabilis, Yarrowia lipolytica and Zygosaccharomyces rouxii. PMID:18684335

  17. Stabilization and encapsulation of photosensitive resveratrol within yeast cell.

    PubMed

    Shi, Guorong; Rao, Liqun; Yu, Huazhong; Xiang, Hua; Yang, Hua; Ji, Runa

    2008-02-12

    The photosensitive resveratrol was successfully encapsulated in yeast cells for the first time, as characterized by FT-IR spectra, fluorescence and confocal micrographs of the yeast cells, resveratrol and microcapsules. The release characteristic of the obtained yeast-encapsulated resveratrol in simulated gastric fluid was evaluated, and its storage stability as a powder was investigated at 25 degrees C/75% relative humidity (RH), 25 degrees C/90% RH and 60 degrees C under the laboratory fluorescent lighting conditions (ca. 300 lx) or in the dark. Also, the scavenging capacity of yeast-encapsulated resveratrol on DPPH radical was compared with that of non-encapsulated resveratrol. It could be demonstrated clearly that no chemical changes occurred during the encapsulation. Besides, the DPPH radical-scavenging activity increased after the encapsulation. In addition, the yeast-encapsulated resveratrol exhibited good stability, and its bioavailability was enhanced as a result of increased solubility of resveratrol and sustained releasing.

  18. Yeast diversity and native vigor for flavor phenotypes.

    PubMed

    Carrau, Francisco; Gaggero, Carina; Aguilar, Pablo S

    2015-03-01

    Saccharomyces cerevisiae, the yeast used widely for beer, bread, cider, and wine production, is the most resourceful eukaryotic model used for genetic engineering. A typical concern about using engineered yeasts for food production might be negative consumer perception of genetically modified organisms. However, we believe the true pitfall of using genetically modified yeasts is their limited capacity to either refine or improve the sensory properties of fermented foods under real production conditions. Alternatively, yeast diversity screening to improve the aroma and flavors could offer groundbreaking opportunities in food biotechnology. We propose a 'Yeast Flavor Diversity Screening' strategy which integrates knowledge from sensory analysis and natural whole-genome evolution with information about flavor metabolic networks and their regulation.

  19. Uniform Yeast Cell Assembly Based on Microfluidic Microgels

    NASA Astrophysics Data System (ADS)

    Chang, Ya-Wen; He, Peng; Marquez, Manuel; Cheng, Zhengdong; Marquez, Samantha M.

    2011-03-01

    We present a novel microgel templated Yeastosome (Yeast- Celloidosome ) based on self-assembly of yeast cells onto liquid-gel interfaces. To organize living cells onto the surface of the gel particles, strong positive charges were first introduced via LbL (layer by layer) polyelectrolyte decoration on monodisperse agarose microgel templates fabricated with a microfluidic flow focusing device. Native yeasts, bearing negative surface charges can then be driven electrostatically to form a monolayer shell around the gel core. Surface coverage/packing density of the yeast biofilm on varying microgel-to-yeast size ratio assemblies is evaluated with optical microscopy. Mechanical properties of the corresponding shells are characterized with buckling or collapse behavior during drying-hydrating cycle. We demonstrate the capability to fabricate narrow size distribution Yeastosome with a soft hydrogel core. The combination of microfluidic fabrication with cell assembly offers excellent control over inner core properties and could enable further hierarchy bio-structures.

  20. Tolerance of budding yeast Saccharomyces cerevisiae to ultra high pressure

    NASA Astrophysics Data System (ADS)

    Shibata, M.; Torigoe, M.; Matsumoto, Y.; Yamamoto, M.; Takizawa, N.; Hada, Y.; Mori, Y.; Takarabe, K.; Ono, F.

    2014-05-01

    Our studies on the tolerance of plants and animals against very high pressure of several GPa have been extended to a smaller sized fungus, the budding yeast Saccharomyces cerevisiae. Several pieces of budding yeast (dry yeast) were sealed in a small teflon capsule with a liquid pressure medium fluorinate, and exposed to 7.5 GPa by using a cubic anvil press. The pressure was kept constant for various duration of time from 2 to 24 h. After the pressure was released, the specimens were brought out from the teflon capsule, and they were cultivated on a potato dextrose agar. It was found that the budding yeast exposed to 7.5 GPa for up to 6 h showed multiplication. However, those exposed to 7.5 GPa for longer than 12 h were found dead. The high pressure tolerance of budding yeast is a little weaker than that of tardigrades.

  1. Yeast species associated with wine grapes in China.

    PubMed

    Li, Shuang-Shi; Cheng, Chao; Li, Zheng; Chen, Jing-Yu; Yan, Bin; Han, Bei-Zhong; Reeves, Malcolm

    2010-03-31

    Having more information on the yeast ecology of grapes is important for wine-makers to produce wine with high quality and typical attributes. China is a significant wine-consuming country and is becoming a serious wine-producer, but little has been reported about the yeast ecology of local ecosystems. This study provides the first step towards the exploitation of the yeast wealth in China's vine-growing regions. The aim of this study was to investigate the yeast population density and diversity on three grape varieties cultivated in four representative vine-growing regions of China. Yeast species diversity was evaluated by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequence analysis of the 5.8S internal transcribed spacer (ITS) ribosomal DNA (rDNA) region of cultivable yeasts. The grapes harbored yeast populations at 10(2)-10(6)CFU/mL, consisting mostly of non-Saccharomyces species. Seventeen different yeast species belonging to eight genera were detected on the grape samples tested, including Hanseniaspora uvarum, Cryptococcus flavescens, Pichia fermentans, Candida zemplinina, Cryptococcus carnescens, Candida inconpicua, Zygosaccharomyces fermentati, Issatchenkia terricola, Candida quercitrusa, Hanseniaspora guilliermondii, Candida bombi, Zygosaccharomyces bailii, Sporidiobolus pararoseus, Cryptococcus magnus, Metschnikowia pulcherrima, Issatchenkia orientalis and Pichia guilliermondii. H. uvarum and C. flavescens were the dominant species present on the grapes. For the first time Sporidiobolus pararoseus was discovered as an inhabitant of the grape ecosystem. The yeast community on grape berries was influenced by the grape chemical composition, vine-variety and vine-growing region. This study is the first to identify the yeast communities associated with grapes in China using molecular methods. The results enrich our knowledge of wine-related microorganisms, and can be used to promote the development of the local wine

  2. Yeast identification in the clinical microbiology laboratory: phenotypical methods.

    PubMed

    Freydiere, A M; Guinet, R; Boiron, P

    2001-02-01

    Emerging yeast pathogens are favoured by increasing numbers of immunocompromised patients and by certain current medical practices. These yeasts differ in their antifungal drug susceptibilities, and rapid species identification is imperative. A large variety of methods have been developed with the aim of facilitating rapid, accurate yeast identification. Significant recent commercial introductions have included species-specific direct enzymatic colour tests, differential chromogenic isolation plates, direct immunological tests, and enhanced manual and automated biochemical and enzymatic panels. Chromogenic isolation media demonstrate better detection rates of yeasts in mixed cultures than traditional media, and allow the direct identification of Candida albicans by means of colony colour. Comparative evaluation of rapid methods for C. albicans identification, including the germ tube test, shows that chromogenic media may be economically advantageous. Accurate tests for single species include the Bichrolatex Albicans and Krusei Color tests, both immunologically based, as well as the Remel Rapid Trehalose Assimilation Broth for C. glabrata. Among broad-spectrum tests, the RapID Yeast Plus system gives same-day identification of clinical yeasts, but performance depends on inoculum density and geographic isolate source. The API 20 C AUX system is considered a reference method, but newer systems such as Auxacolor and Fungichrom are as accurate and are more convenient. Among automated systems, the ID 32 C strip, the Vitek Yeast Biochemical Card and the Vitek 2 ID-YST system correctly identify >93% of common yeasts, but the ID-YST is the most accurate with uncommon yeasts, including C. dubliniensis. Spectroscopic methods such as Fourier transformed-infrared spectroscopy offer potential advantages for the future. Overall, the advantages of rapid yeast identification methods include relative simplicity and low cost. For all rapid methods, meticulous, standardized

  3. Lipid raft involvement in yeast cell growth and death

    PubMed Central

    Mollinedo, Faustino

    2012-01-01

    The notion that cellular membranes contain distinct microdomains, acting as scaffolds for signal transduction processes, has gained considerable momentum. In particular, a class of such domains that is rich in sphingolipids and cholesterol, termed as lipid rafts, is thought to compartmentalize the plasma membrane, and to have important roles in survival and cell death signaling in mammalian cells. Likewise, yeast lipid rafts are membrane domains enriched in sphingolipids and ergosterol, the yeast counterpart of mammalian cholesterol. Sterol-rich membrane domains have been identified in several fungal species, including the budding yeast Saccharomyces cerevisiae, the fission yeast Schizosaccharomyces pombe as well as the pathogens Candida albicans and Cryptococcus neoformans. Yeast rafts have been mainly involved in membrane trafficking, but increasing evidence implicates rafts in a wide range of additional cellular processes. Yeast lipid rafts house biologically important proteins involved in the proper function of yeast, such as proteins that control Na+, K+, and pH homeostasis, which influence many cellular processes, including cell growth and death. Membrane raft constituents affect drug susceptibility, and drugs interacting with sterols alter raft composition and membrane integrity, leading to yeast cell death. Because of the genetic tractability of yeast, analysis of yeast rafts could be an excellent model to approach unanswered questions of mammalian raft biology, and to understand the role of lipid rafts in the regulation of cell death and survival in human cells. A better insight in raft biology might lead to envisage new raft-mediated approaches to the treatment of human diseases where regulation of cell death and survival is critical, such as cancer and neurodegenerative diseases. PMID:23087902

  4. High-throughput screening of improved protease inhibitors using a yeast cell surface display system and a yeast cell chip.

    PubMed

    Aoki, Wataru; Yoshino, Yuichi; Morisaka, Hironobu; Tsunetomo, Keiji; Koyo, Hirotaka; Kamiya, Shinji; Kawata, Noriyuki; Kuroda, Kouichi; Ueda, Mitsuyoshi

    2011-01-01

    Protease-targeted inhibitors have been promising pharmaceuticals. Here, we combined a yeast cell surface display system with a yeast cell chip for the high-throughput screening of protease inhibitors, and succeeded in improving the activity of a protease inhibitor.

  5. Introducing a New Breed of Wine Yeast: Interspecific Hybridisation between a Commercial Saccharomyces cerevisiae Wine Yeast and Saccharomyces mikatae

    PubMed Central

    Bellon, Jennifer R.; Schmid, Frank; Capone, Dimitra L.; Dunn, Barbara L.; Chambers, Paul J.

    2013-01-01

    Interspecific hybrids are commonplace in agriculture and horticulture; bread wheat and grapefruit are but two examples. The benefits derived from interspecific hybridisation include the potential of generating advantageous transgressive phenotypes. This paper describes the generation of a new breed of wine yeast by interspecific hybridisation between a commercial Saccharomyces cerevisiae wine yeast strain and Saccharomyces mikatae, a species hitherto not associated with industrial fermentation environs. While commercially available wine yeast strains provide consistent and reliable fermentations, wines produced using single inocula are thought to lack the sensory complexity and rounded palate structure obtained from spontaneous fermentations. In contrast, interspecific yeast hybrids have the potential to deliver increased complexity to wine sensory properties and alternative wine styles through the formation of novel, and wider ranging, yeast volatile fermentation metabolite profiles, whilst maintaining the robustness of the wine yeast parent. Screening of newly generated hybrids from a cross between a S. cerevisiae wine yeast and S. mikatae (closely-related but ecologically distant members of the Saccharomyces sensu stricto clade), has identified progeny with robust fermentation properties and winemaking potential. Chemical analysis showed that, relative to the S. cerevisiae wine yeast parent, hybrids produced wines with different concentrations of volatile metabolites that are known to contribute to wine flavour and aroma, including flavour compounds associated with non-Saccharomyces species. The new S. cerevisiae x S. mikatae hybrids have the potential to produce complex wines akin to products of spontaneous fermentation while giving winemakers the safeguard of an inoculated ferment. PMID:23614011

  6. Introducing a new breed of wine yeast: interspecific hybridisation between a commercial Saccharomyces cerevisiae wine yeast and Saccharomyces mikatae.

    PubMed

    Bellon, Jennifer R; Schmid, Frank; Capone, Dimitra L; Dunn, Barbara L; Chambers, Paul J

    2013-01-01

    Interspecific hybrids are commonplace in agriculture and horticulture; bread wheat and grapefruit are but two examples. The benefits derived from interspecific hybridisation include the potential of generating advantageous transgressive phenotypes. This paper describes the generation of a new breed of wine yeast by interspecific hybridisation between a commercial Saccharomyces cerevisiae wine yeast strain and Saccharomyces mikatae, a species hitherto not associated with industrial fermentation environs. While commercially available wine yeast strains provide consistent and reliable fermentations, wines produced using single inocula are thought to lack the sensory complexity and rounded palate structure obtained from spontaneous fermentations. In contrast, interspecific yeast hybrids have the potential to deliver increased complexity to wine sensory properties and alternative wine styles through the formation of novel, and wider ranging, yeast volatile fermentation metabolite profiles, whilst maintaining the robustness of the wine yeast parent. Screening of newly generated hybrids from a cross between a S. cerevisiae wine yeast and S. mikatae (closely-related but ecologically distant members of the Saccharomyces sensu stricto clade), has identified progeny with robust fermentation properties and winemaking potential. Chemical analysis showed that, relative to the S. cerevisiae wine yeast parent, hybrids produced wines with different concentrations of volatile metabolites that are known to contribute to wine flavour and aroma, including flavour compounds associated with non-Saccharomyces species. The new S. cerevisiae x S. mikatae hybrids have the potential to produce complex wines akin to products of spontaneous fermentation while giving winemakers the safeguard of an inoculated ferment.

  7. Clinical and tree hollow populations of human pathogenic yeast in Hamilton, Ontario, Canada are different.

    PubMed

    Carvalho, Chris; Yang, Jiaqi; Vogan, Aaron; Maganti, Harinad; Yamamura, Deborah; Xu, Jianping

    2014-05-01

    Yeast are among the most frequent pathogens in humans. The dominant yeast causing human infections belong to the genus Candida and Candida albicans is the most frequently isolated species. However, several non-C. albicans species are becoming increasingly common in patients worldwide. The relationships between yeast in humans and the natural environments remain poorly understood. Furthermore, it is often difficult to identify or exclude the origins of disease-causing yeast from specific environmental reservoirs. In this study, we compared the yeast isolates from tree hollows and from clinics in Hamilton, Ontario, Canada. Our surveys and analyses showed significant differences in yeast species composition, in their temporal dynamics, and in yeast genotypes between isolates from tree hollows and hospitals. Our results are inconsistent with the hypothesis that yeast from trees constitute a significant source of pathogenic yeast in humans in this region. Similarly, the yeast in humans and clinics do not appear to contribute to yeast in tree hollows.

  8. A Proteome-wide Fission Yeast Interactome Reveals Network Evolution Principles from Yeasts to Human.

    PubMed

    Vo, Tommy V; Das, Jishnu; Meyer, Michael J; Cordero, Nicolas A; Akturk, Nurten; Wei, Xiaomu; Fair, Benjamin J; Degatano, Andrew G; Fragoza, Robert; Liu, Lisa G; Matsuyama, Akihisa; Trickey, Michelle; Horibata, Sachi; Grimson, Andrew; Yamano, Hiroyuki; Yoshida, Minoru; Roth, Frederick P; Pleiss, Jeffrey A; Xia, Yu; Yu, Haiyuan

    2016-01-14

    Here, we present FissionNet, a proteome-wide binary protein interactome for S. pombe, comprising 2,278 high-quality interactions, of which ∼ 50% were previously not reported in any species. FissionNet unravels previously unreported interactions implicated in processes such as gene silencing and pre-mRNA splicing. We developed a rigorous network comparison framework that accounts for assay sensitivity and specificity, revealing extensive species-specific network rewiring between fission yeast, budding yeast, and human. Surprisingly, although genes are better conserved between the yeasts, S. pombe interactions are significantly better conserved in human than in S. cerevisiae. Our framework also reveals that different modes of gene duplication influence the extent to which paralogous proteins are functionally repurposed. Finally, cross-species interactome mapping demonstrates that coevolution of interacting proteins is remarkably prevalent, a result with important implications for studying human disease in model organisms. Overall, FissionNet is a valuable resource for understanding protein functions and their evolution.

  9. Biocavity laser spectroscopy of genetically altered yeast cells and isolated yeast mitochondria

    NASA Astrophysics Data System (ADS)

    Gourley, Paul L.; Hendricks, Judy K.; McDonald, Anthony E.; Copeland, R. Guild; Naviaux, Robert K.; Yaffe, Michael P.

    2006-02-01

    We report an analysis of 2 yeast cell mutants using biocavity laser spectroscopy. The two yeast strains differed only by the presence or absence of mitochondrial DNA. Strain 104 is a wild-type (ρ +) strain of the baker's yeast, Saccharomyces cerevisiae. Strain 110 was derived from strain 104 by removal of its mitochondrial DNA (mtDNA). Removal of mtDNA causes strain 110 to grow as a "petite" (ρ -), named because it forms small colonies (of fewer cells because it grows more slowly) on agar plates supplemented with a variety of different carbon sources. The absence of mitochondrial DNA results in the complete loss of all the mtDNA-encoded proteins and RNAs, and loss of the pigmented, heme-containing cytochromes a and b. These cells have mitochondria, but the mitochondria lack the normal respiratory chain complexes I, III, IV, and V. Complex II is preserved because its subunits are encoded by genes located in nuclear DNA. The frequency distributions of the peak shifts produced by wild-type and petite cells and mitochondria show striking differences in the symmetry and patterns of the distributions. Wild-type ρ + cells (104) and mitochondria produced nearly symmetric, Gaussian distributions. The ρ - cells (110) and mitochondria showed striking asymmetry and skew that appeared to follow a Poisson distribution.

  10. Anhydrobiosis in yeast: cell wall mannoproteins are important for yeast Saccharomyces cerevisiae resistance to dehydration.

    PubMed

    Borovikova, Diana; Teparić, Renata; Mrša, Vladimir; Rapoport, Alexander

    2016-08-01

    The state of anhydrobiosis is linked with the reversible delay of metabolism as a result of strong dehydration of cells, and is widely distributed in nature. A number of factors responsible for the maintenance of organisms' viability in these conditions have been revealed. This study was directed to understanding how changes in cell wall structure may influence the resistance of yeasts to dehydration-rehydration. Mutants lacking various cell wall mannoproteins were tested to address this issue. It was revealed that mutants lacking proteins belonging to two structurally and functionally unrelated groups (proteins non-covalently attached to the cell wall, and Pir proteins) possessed significantly lower cell resistance to dehydration-rehydration than the mother wild-type strain. At the same time, the absence of the GPI-anchored cell wall protein Ccw12 unexpectedly resulted in an increase of cell resistance to this treatment; this phenomenon is explained by the compensatory synthesis of chitin. The results clearly indicate that the cell wall structure/composition relates to parameters strongly influencing yeast viability during the processes of dehydration-rehydration, and that damage to cell wall proteins during yeast desiccation can be an important factor leading to cell death. Copyright © 2016 John Wiley & Sons, Ltd.

  11. A proteome-wide fission yeast interactome reveals network evolution principles from yeasts to human

    PubMed Central

    Vo, Tommy V.; Das, Jishnu; Meyer, Michael J.; Cordero, Nicolas A.; Akturk, Nurten; Wei, Xiaomu; Fair, Benjamin J.; Degatano, Andrew G.; Fragoza, Robert; Liu, Lisa G.; Matsuyama, Akihisa; Trickey, Michelle; Horibata, Sachi; Grimson, Andrew; Yamano, Hiroyuki; Yoshida, Minoru; Roth, Frederick P.; Pleiss, Jeffrey A.; Xia, Yu; Yu, Haiyuan

    2015-01-01

    SUMMARY Here, we present FissionNet, a proteome-wide binary protein interactome for S. pombe, comprising 2,278 high-quality interactions, of which ~50% were previously not reported in any species. FissionNet unravels previously unreported interactions implicated in processes such as gene silencing and pre-mRNA splicing. We developed a rigorous network comparison framework that accounts for assay sensitivity and specificity, revealing extensive species-specific network rewiring between fission yeast, budding yeast, and human. Surprisingly, although genes are better conserved between the yeasts, S. pombe interactions are significantly better conserved in human than in S. cerevisiae. Our framework also reveals that different modes of gene duplication influence the extent to which paralogous proteins are functionally repurposed. Finally, cross-species interactome mapping demonstrates that coevolution of interacting proteins is remarkably prevalent, a result with important implications for studying human disease in model organisms. Overall, FissionNet is a valuable resource for understanding protein functions and their evolution. PMID:26771498

  12. A Nematode Growth Factor from Baker's Yeast

    PubMed Central

    Buecher, E. J.; Hansen, E. L.; Gottfried, T.

    1970-01-01

    An extract prepared from commercially available yeast supported maturation of the free-living nematode Caenorhabditis briggsae. The extract can be used to supplement a chemically defined medium or, after a limited dialysis, as a complete medium. Several biologically active fractions were prepared; those containing larger amounts of ribonucleic acid (RNA) had greater biological activity, the most active being a pellet resuspended after centrifugation at 30,000 × g for 30 min. This fraction could be substituted for serum in a medium which supports the maturation of the animal parasites Trichinella spiralis and Hymenolepis nana. Addition of protamine sulfate decreased the RNA content, leaving inactive protein fractions which could be reactivated by specific treatments that caused protein precipitation. It is postulated that biological activity is associated with protein sedimented with ribosomes. PMID:19322277

  13. Natural gene expression variation studies in yeast.

    PubMed

    Thompson, Dawn A; Cubillos, Francisco A

    2017-01-01

    The rise of sequence information across different yeast species and strains is driving an increasing number of studies in the emerging field of genomics to associate polymorphic variants, mRNA abundance and phenotypic differences between individuals. Here, we gathered evidence from recent studies covering several layers that define the genotype-phenotype gap, such as mRNA abundance, allele-specific expression and translation efficiency to demonstrate how genetic variants co-evolve and define an individual's genome. Moreover, we exposed several antecedents where inter- and intra-specific studies led to opposite conclusions, probably owing to genetic divergence. Future studies in this area will benefit from the access to a massive array of well-annotated genomes and new sequencing technologies, which will allow the fine breakdown of the complex layers that delineate the genotype-phenotype map. Copyright © 2016 John Wiley & Sons, Ltd.

  14. Nuclear size control in fission yeast.

    PubMed

    Neumann, Frank R; Nurse, Paul

    2007-11-19

    A long-standing biological question is how a eukaryotic cell controls the size of its nucleus. We report here that in fission yeast, nuclear size is proportional to cell size over a 35-fold range, and use mutants to show that a 16-fold change in nuclear DNA content does not influence the relative size of the nucleus. Multi-nucleated cells with unevenly distributed nuclei reveal that nuclei surrounded by a greater volume of cytoplasm grow more rapidly. During interphase of the cell cycle nuclear growth is proportional to cell growth, and during mitosis there is a rapid expansion of the nuclear envelope. When the nuclear/cell (N/C) volume ratio is increased by centrifugation or genetic manipulation, nuclear growth is arrested while the cell continues to grow; in contrast, low N/C ratios are rapidly corrected by nuclear growth. We propose that there is a general cellular control linking nuclear growth to cell size.

  15. Transcriptional regulation at the yeast nuclear envelope

    PubMed Central

    Steglich, Babett; Sazer, Shelley; Ekwall, Karl

    2013-01-01

    The spatial organization of the genome inside the nucleus affects many nuclear processes, such as DNA replication, DNA repair, and gene transcription. In metazoans, the nuclear periphery harbors mainly repressed genes that associate with the nuclear lamina. This review discusses how peripheral positioning is connected to transcriptional regulation in yeasts. Tethering of reporter genes to the nuclear envelope was found to result in transcriptional silencing. Similarly, repression of the silent mating type loci and subtelomeric genes is influenced by their position close to the nuclear envelope. In contrast, active genes are bound by nucleoporins and inducible genes associate with the nuclear pore complex upon activation. Taken together, these results portray the nuclear envelope as a platform for transcriptional regulation, both through activation at nuclear pores and silencing at the nuclear envelope. PMID:24021962

  16. Architecture of the yeast Elongator complex.

    PubMed

    Dauden, Maria I; Kosinski, Jan; Kolaj-Robin, Olga; Desfosses, Ambroise; Ori, Alessandro; Faux, Celine; Hoffmann, Niklas A; Onuma, Osita F; Breunig, Karin D; Beck, Martin; Sachse, Carsten; Séraphin, Bertrand; Glatt, Sebastian; Müller, Christoph W

    2017-02-01

    The highly conserved eukaryotic Elongator complex performs specific chemical modifications on wobble base uridines of tRNAs, which are essential for proteome stability and homeostasis. The complex is formed by six individual subunits (Elp1-6) that are all equally important for its tRNA modification activity. However, its overall architecture and the detailed reaction mechanism remain elusive. Here, we report the structures of the fully assembled yeast Elongator and the Elp123 sub-complex solved by an integrative structure determination approach showing that two copies of the Elp1, Elp2, and Elp3 subunits form a two-lobed scaffold, which binds Elp456 asymmetrically. Our topological models are consistent with previous studies on individual subunits and further validated by complementary biochemical analyses. Our study provides a structural framework on how the tRNA modification activity is carried out by Elongator.

  17. Import of ribosomal proteins into yeast mitochondria.

    PubMed

    Woellhaf, Michael W; Hansen, Katja G; Garth, Christoph; Herrmann, Johannes M

    2014-12-01

    Mitochondrial ribosomes of baker's yeast contain at least 78 protein subunits. All but one of these proteins are nuclear-encoded, synthesized on cytosolic ribosomes, and imported into the matrix for biogenesis. The import of matrix proteins typically relies on N-terminal mitochondrial targeting sequences that form positively charged amphipathic helices. Interestingly, the N-terminal regions of many ribosomal proteins do not closely match the characteristics of matrix targeting sequences, suggesting that the import processes of these proteins might deviate to some extent from the general import route. So far, the biogenesis of only two ribosomal proteins, Mrpl32 and Mrp10, was studied experimentally and indeed showed surprising differences to the import of other preproteins. In this review article we summarize the current knowledge on the transport of proteins into the mitochondrial matrix, and thereby specifically focus on proteins of the mitochondrial ribosome.

  18. Yeast Gal4: a transcriptional paradigm revisited

    PubMed Central

    Traven, Ana; Jelicic, Branka; Sopta, Mary

    2006-01-01

    During the past two decades, the yeast Gal4 protein has been used as a model for studying transcriptional activation in eukaryotes. Many of the properties of transcriptional regulation first demonstrated for Gal4 have since been shown to be reiterated in the function of several other eukaryotic transcriptional regulators. Technological advances based on the transcriptional properties of this factor—such as the two-hybrid technology and Gal4-inducible systems for controlled gene expression—have had far-reaching influences in fields beyond transcription. In this review, we provide an updated account of Gal4 function, including data from new technologies that have been recently applied to the study of the GAL network. PMID:16670683

  19. Cyanohydrin reactions enhance glycolytic oscillations in yeast.

    PubMed

    Hald, Bjørn Olav; Nielsen, Astrid Gram; Tortzen, Christian; Sørensen, Preben Graae

    2015-01-01

    Synchronous metabolic oscillations can be induced in yeast by addition of glucose and removal of extracellular acetaldehyde (ACAx). Compared to other means of ACAx removal, cyanide robustly induces oscillations, indicating additional cyanide reactions besides ACA to lactonitrile conversion. Here, (13)C NMR is used to confirm our previous hypothesis, that cyanide directly affects glycolytic fluxes through reaction with carbonyl-containing compounds. Intracellularly, at least 3 cyanohydrins were identified. Extracellularly, all signals could be identified and lactonitrile was found to account for ~66% of total cyanide removal. Simulations of our updated computational model show that intracellular cyanide reactions increase the amplitude of oscillations and that cyanide addition lowers [ACA] instantaneously. We conclude that cyanide provides the following means of inducing global oscillations: a) by reducing [ACAx] relative to oscillation amplitude, b) by targeting multiple intracellular carbonyl compounds during fermentation, and c) by acting as a phase resetting stimulus.

  20. Ordering the Final Events in Yeast Exocytosis

    PubMed Central

    Grote, Eric; Carr, Chavela M.; Novick, Peter J.

    2000-01-01

    In yeast, assembly of exocytic soluble N-ethylmaleimide–sensitive fusion protein (NSF) attachment protein receptor (SNARE) complexes between the secretory vesicle SNARE Sncp and the plasma membrane SNAREs Ssop and Sec9p occurs at a late stage of the exocytic reaction. Mutations that block either secretory vesicle delivery or tethering prevent SNARE complex assembly and the localization of Sec1p, a SNARE complex binding protein, to sites of secretion. By contrast, wild-type levels of SNARE complexes persist in the sec1-1 mutant after a secretory block is imposed, suggesting a role for Sec1p after SNARE complex assembly. In the sec18-1 mutant, cis-SNARE complexes containing surface-accessible Sncp accumulate in the plasma membrane. Thus, one function of Sec18p is to disassemble SNARE complexes on the postfusion membrane. PMID:11038189

  1. Phyllosphere yeasts rapidly break down biodegradable plastics.

    PubMed

    Kitamoto, Hiroko K; Shinozaki, Yukiko; Cao, Xiao-Hong; Morita, Tomotake; Konishi, Masaaki; Tago, Kanako; Kajiwara, Hideyuki; Koitabashi, Motoo; Yoshida, Shigenobu; Watanabe, Takashi; Sameshima-Yamashita, Yuka; Nakajima-Kambe, Toshiaki; Tsushima, Seiya

    2011-11-29

    The use of biodegradable plastics can reduce the accumulation of environmentally persistent plastic wastes. The rate of degradation of biodegradable plastics depends on environmental conditions and is highly variable. Techniques for achieving more consistent degradation are needed. However, only a few microorganisms involved in the degradation process have been isolated so far from the environment. Here, we show that Pseudozyma spp. yeasts, which are common in the phyllosphere and are easily isolated from plant surfaces, displayed strong degradation activity on films made from poly-butylene succinate or poly-butylene succinate-co-adipate. Strains of P. antarctica isolated from leaves and husks of paddy rice displayed strong degradation activity on these films at 30°C. The type strain, P. antarctica JCM 10317, and Pseudozyma spp. strains from phyllosphere secreted a biodegradable plastic-degrading enzyme with a molecular mass of about 22 kDa. Reliable source of biodegradable plastic-degrading microorganisms are now in our hands.

  2. Preparation of Total RNA from Fission Yeast.

    PubMed

    Bähler, Jürg; Wise, Jo Ann

    2017-04-03

    Treatment with hot phenol breaks open fission yeast cells and begins to strip away bound proteins from RNA. Deproteinization is completed by multiple extractions with chloroform/isoamyl alcohol and separation of the aqueous and organic phases using MaXtract gel, an inert material that acts as a physical barrier between the phases. The final step is concentration of the RNA by ethanol precipitation. The protocol can be used to prepare RNA from several cultures grown in parallel, but it is important not to process too many samples at once because delays can be detrimental to RNA quality. A reasonable number of samples to process at once would be three to four for microarray or RNA sequencing analyses and six for preliminary investigations of mutants implicated in RNA metabolism.

  3. Biofilm/Mat assays for budding yeast.

    PubMed

    Cullen, Paul J

    2015-02-02

    Many microbial species form biofilms/mats under nutrient-limiting conditions, and fungal pathogens rely on this social behavior for virulence. In budding yeast, mat formation is dependent on the mucin-like flocculin Flo11, which promotes cell-to-cell and cell-to-substrate adhesion in mats. The biofilm/mat assays described here allow the evaluation of the role of Flo11 in the formation of mats. Cells are grown on surfaces with different degrees of rigidity to assess their expansion and three-dimensional architecture, and the cells are also exposed to plastic surfaces to quantify their adherence. These assays are broadly applicable to studying biofilm/mat formation in microbial species.

  4. Chromatographic purification of highly active yeast ribosomes.

    PubMed

    Meskauskas, Arturas; Leshin, Jonathan A; Dinman, Jonathan D

    2011-10-24

    Eukaryotic ribosomes are much more labile as compared to their eubacterial and archael counterparts, thus posing a significant challenge to researchers. Particularly troublesome is the fact that lysis of cells releases a large number of proteases and nucleases which can degrade ribosomes. Thus, it is important to separate ribosomes from these enzymes as quickly as possible. Unfortunately, conventional differential ultracentrifugation methods leaves ribosomes exposed to these enzymes for unacceptably long periods of time, impacting their structural integrity and functionality. To address this problem, we utilize a chromatographic method using a cysteine charged Sulfolink resin. This simple and rapid application significantly reduces co-purifying proteolytic and nucleolytic activities, producing high yields of intact, highly biochemically active yeast ribosomes. We suggest that this method should also be applicable to mammalian ribosomes. The simplicity of the method, and the enhanced purity and activity of chromatographically purified ribosome represents a significant technical advancement for the study of eukaryotic ribosomes.

  5. Combinatorial Regulation in Yeast Transcription Networks

    NASA Astrophysics Data System (ADS)

    Li, Hao

    2006-03-01

    Yeast has evolved a complex network to regulate its transcriptional program in response to changes in environment. It is quite common that in response to an external stimulus, several transcription factors will be activated and they work in combinations to control different subsets of genes in the genome. We are interested in how the promoters of genes are designed to integrate signals from multiple transcription factors and what are the functional and evolutionary constraints. To answer how, we have developed a number of computational algorithms to systematically map the binding sites and target genes of transcription factors using sequence and gene expression data. To analyze the functional constraints, we have employed mechanistic models to study the dynamic behavior of genes regulated by multiple factors. We have also developed methods to trace the evolution of transcriptional networks via comparative analysis of multiple species.

  6. Oxidative stress and antioxidant response in a thermotolerant yeast.

    PubMed

    Mejía-Barajas, Jorge A; Montoya-Pérez, Rocío; Salgado-Garciglia, Rafael; Aguilera-Aguirre, Leopoldo; Cortés-Rojo, Christian; Mejía-Zepeda, Ricardo; Arellano-Plaza, Melchor; Saavedra-Molina, Alfredo

    Stress tolerance is a key attribute that must be considered when using yeast cells for industrial applications. High temperature is one factor that can cause stress in yeast. High environmental temperature in particular may exert a natural selection pressure to evolve yeasts into thermotolerant strains. In the present study, three yeasts (Saccharomyces cerevisiae, MC4, and Kluyveromyces marxianus, OFF1 and SLP1) isolated from hot environments were exposed to increased temperatures and were then compared with a laboratory yeast strain. Their resistance to high temperature, oxidative stress, and antioxidant response were evaluated, along with the fatty acid composition of their cell membranes. The SLP1 strain showed a higher specific growth rate, biomass yield, and biomass volumetric productivity while also showing lower duplication time, reactive oxygen species (ROS) production, and lipid peroxidation. In addition, the SLP1 strain demonstrated more catalase activity after temperature was increased, and this strain also showed membranes enriched in saturated fatty acids. It is concluded that the SLP1 yeast strain is a thermotolerant yeast with less oxidative stress and a greater antioxidant response. Therefore, this strain could be used for fermentation at high temperatures.

  7. Yeast Biomass Production in Brewery's Spent Grains Hemicellulosic Hydrolyzate

    NASA Astrophysics Data System (ADS)

    Duarte, Luís C.; Carvalheiro, Florbela; Lopes, Sónia; Neves, Ines; Gírio, Francisco M.

    Yeast single-cell protein and yeast extract, in particular, are two products which have many feed, food, pharmaceutical, and biotechnological applications. However, many of these applications are limited by their market price. Specifically, the yeast extract requirements for culture media are one of the major technical hurdles to be overcome for the development of low-cost fermentation routes for several top value chemicals in a biorefinery framework. A potential biotechnical solution is the production of yeast biomass from the hemicellulosic fraction stream. The growth of three pentose-assimilating yeast cell factories, Debaryomyces hansenii, Kluyveromyces marxianus, and Pichia stipitis was compared using non-detoxified brewery's spent grains hemicellulosic hydrolyzate supplemented with mineral nutrients. The yeasts exhibited different specific growth rates, biomass productivities, and yields being D. hansenii as the yeast species that presented the best performance, assimilating all sugars and noteworthy consuming most of the hydrolyzate inhibitors. Under optimized conditions, D. hansenii displayed a maximum specific growth rate, biomass yield, and productivity of 0.34 h-1, 0.61 g g-1, and 0.56 g 1-1 h-1, respectively. The nutritional profile of D. hansenii was thoroughly evaluated, and it compares favorably to others reported in literature. It contains considerable amounts of some essential amino acids and a high ratio of unsaturated over saturated fatty acids.

  8. Sensitivity of yeasts to amphotericin B and 5-fluorocytosine.

    PubMed

    Abdul-Samad, S; Arumugham, G; Yasin, M S

    1989-08-01

    One hundred and forty-four clinical yeast isolates were tested for antifungal susceptibility to Amphotericin B (AMB) and 5-Fluorocytosine (5FC). 61% (88 of 144) of the total yeast isolates were C. albicans. Yeasts were most frequently isolated from high vaginal swabs. High vaginal swabs constituted 64% (92 of 144) of the total number of specimens. Antifungal susceptibility testing of yeasts was conducted by employing an agar dilution technique. 76% (67 of 88) of C. albicans demonstrated MIC values of less than or equal to 1.0 ug/ml to 5FC. All yeasts tested against AMB demonstrated MICs of less than or equal to 0.25 ug/ml. Resistance to 5FC and AMB was defined as any isolate demonstrating an MIC of greater than 16 ug/ml and MIC greater than or equal to 2 ug/ml respectively. Based on this definition approximately 6% of total yeasts and 8% of C. albicans were resistant to 5FC. All yeasts tested were sensitive to AMB.

  9. Yeast cell-based analysis of human lactate dehydrogenase isoforms.

    PubMed

    Mohamed, Lulu Ahmed; Tachikawa, Hiroyuki; Gao, Xiao-Dong; Nakanishi, Hideki

    2015-12-01

    Human lactate dehydrogenase (LDH) has attracted attention as a potential target for cancer therapy and contraception. In this study, we reconstituted human lactic acid fermentation in Saccharomyces cerevisiae, with the goal of constructing a yeast cell-based LDH assay system. pdc null mutant yeast (mutated in the endogenous pyruvate decarboxylase genes) are unable to perform alcoholic fermentation; when grown in the presence of an electron transport chain inhibitor, pdc null strains exhibit a growth defect. We found that introduction of the human gene encoding LDHA complemented the pdc growth defect; this complementation depended on LDHA catalytic activity. Similarly, introduction of the human LDHC complemented the pdc growth defect, even though LDHC did not generate lactate at the levels seen with LDHA. In contrast, the human LDHB did not complement the yeast pdc null mutant, although LDHB did generate lactate in yeast cells. Expression of LDHB as a red fluorescent protein (RFP) fusion yielded blebs in yeast, whereas LDHA-RFP and LDHC-RFP fusion proteins exhibited cytosolic distribution. Thus, LDHB exhibits several unique features when expressed in yeast cells. Because yeast cells are amenable to genetic analysis and cell-based high-throughput screening, our pdc/LDH strains are expected to be of use for versatile analyses of human LDH.

  10. Characterization of isolated yeast growth response to methionine analogs.

    PubMed

    Saengkerdsub, Suwat; Lingbeck, Jody M; Wilkinson, Heather H; O'Bryan, Corliss A; Crandall, Philip G; Muthaiyan, Arunachalam; Biswas, Debabrata; Ricke, Steven C

    2013-01-01

    Methionine is one of the first limiting amino acids in poultry nutrition. The use of methionine-rich natural feed ingredients, such as soybean meal or rapeseed meal may lead to negative environmental consequences. Amino acid supplementation leads to reduced use of protein-rich ingredients. The objectives of this study were isolation of potentially high content methionine-containing yeasts, quantification of methionine content in yeasts and their respective growth response to methionine analogs. Minimal medium was used as the selection medium and the isolation medium of methionine-producing yeasts from yeast collection and environmental samples, respectively. Two yeasts previously collected along with six additional strains isolated from Caucasian kefir grains, air-trapped, cantaloupe, and three soil samples could grow on minimal medium. Only two of the newly isolated strains, K1 and C1, grew in minimal medium supplied with either methionine analogs ethionine or norleucine at 0.5% (w/v). Based on large subunit rRNA sequences, these isolated strains were identified as Pichia udriavzevii/Issatchenkia orientalis. P. kudriavzevii/I. orentalis is a generally recognized as a safe organism. In addition, methionine produced by K1 and C1 yeast hydrolysate yielded 1.3 ± 0.01 and 1.1 ± 0.01 mg g(-1) dry cell. Yeast strain K1 may be suitable as a potential source of methionine for dietary supplements in organic poultry feed but may require growth conditions to further increase their methionine content.

  11. Yeast responses to stresses associated with industrial brewery handling.

    PubMed

    Gibson, Brian R; Lawrence, Stephen J; Leclaire, Jessica P R; Powell, Chris D; Smart, Katherine A

    2007-09-01

    During brewery handling, production strains of yeast must respond to fluctuations in dissolved oxygen concentration, pH, osmolarity, ethanol concentration, nutrient supply and temperature. Fermentation performance of brewing yeast strains is dependent on their ability to adapt to these changes, particularly during batch brewery fermentation which involves the recycling (repitching) of a single yeast culture (slurry) over a number of fermentations (generations). Modern practices, such as the use of high-gravity worts and preparation of dried yeast for use as an inoculum, have increased the magnitude of the stresses to which the cell is subjected. The ability of yeast to respond effectively to these conditions is essential not only for beer production but also for maintaining the fermentation fitness of yeast for use in subsequent fermentations. During brewery handling, cells inhabit a complex environment and our understanding of stress responses under such conditions is limited. The advent of techniques capable of determining genomic and proteomic changes within the cell is likely vastly to improve our knowledge of yeast stress responses during industrial brewery handling.

  12. Measuring mitotic spindle dynamics in budding yeast

    NASA Astrophysics Data System (ADS)

    Plumb, Kemp

    In order to carry out its life cycle and produce viable progeny through cell division, a cell must successfully coordinate and execute a number of complex processes with high fidelity, in an environment dominated by thermal noise. One important example of such a process is the assembly and positioning of the mitotic spindle prior to chromosome segregation. The mitotic spindle is a modular structure composed of two spindle pole bodies, separated in space and spanned by filamentous proteins called microtubules, along which the genetic material of the cell is held. The spindle is responsible for alignment and subsequent segregation of chromosomes into two equal parts; proper spindle positioning and timing ensure that genetic material is appropriately divided amongst mother and daughter cells. In this thesis, I describe fluorescence confocal microscopy and automated image analysis algorithms, which I have used to observe and analyze the real space dynamics of the mitotic spindle in budding yeast. The software can locate structures in three spatial dimensions and track their movement in time. By selecting fluorescent proteins which specifically label the spindle poles and cell periphery, mitotic spindle dynamics have been measured in a coordinate system relevant to the cell division. I describe how I have characterised the accuracy and precision of the algorithms by simulating fluorescence data for both spindle poles and the budding yeast cell surface. In this thesis I also describe the construction of a microfluidic apparatus that allows for the measurement of long time-scale dynamics of individual cells and the development of a cell population. The tools developed in this thesis work will facilitate in-depth quantitative analysis of the non-equilibrium processes in living cells.

  13. Unsuspected pyocyanin effect in yeast under anaerobiosis.

    PubMed

    Barakat, Rana; Goubet, Isabelle; Manon, Stephen; Berges, Thierry; Rosenfeld, Eric

    2014-02-01

    The blue-green phenazine, Pyocyanin (PYO), is a well-known virulence factor produced by Pseudomonas aeruginosa, notably during cystic fibrosis lung infections. It is toxic to both eukaryotic and bacterial cells and several mechanisms, including the induction of oxidative stress, have been postulated. However, the mechanism of PYO toxicity under the physiological conditions of oxygen limitation that are encountered by P. aeruginosa and by target organisms in vivo remains unclear. In this study, wild-type and mutant strains of the yeast Saccharomyces cerevisiae were used as an effective eukaryotic model to determine the toxicity of PYO (100-500 μmol/L) under key growth conditions. Under respiro-fermentative conditions (with glucose as substrate), WT strains and certain H2 O2 -hypersensitive strains showed a low-toxic response to PYO. Under respiratory conditions (with glycerol as substrate) all the strains tested were significantly more sensitive to PYO. Four antioxidants were tested but only N-acetylcysteine was capable of partially counteracting PYO toxicity. PYO did not appear to affect short-term respiratory O2 uptake, but it did seem to interfere with cyanide-poisoned mitochondria through a complex III-dependent mechanism. Therefore, a combination of oxidative stress and respiration disturbance could partly explain aerobic PYO toxicity. Surprisingly, the toxic effects of PYO were more significant under anaerobic conditions. More pronounced effects were observed in several strains including a 'petite' strain lacking mitochondrial DNA, strains with increased or decreased levels of ABC transporters, and strains deficient in DNA damage repair. Therefore, even though PYO is toxic for actively respiring cells, O2 may indirectly protect the cells from the higher anaerobic-linked toxicity of PYO. The increased sensitivity to PYO under anaerobic conditions is not unique to S. cerevisiae and was also observed in another yeast, Candida albicans.

  14. The yeast spectrum of the 'tea fungus Kombucha'.

    PubMed

    Mayser, P; Fromme, S; Leitzmann, C; Gründer, K

    1995-01-01

    The tea fungus 'Kombucha' is a symbiosis of Acetobacter, including Acetobacter xylinum as a characteristic species, and various yeasts. A characteristic yeast species or genus has not yet been identified. Kombucha is mainly cultivated in sugared black tea to produce a slightly acidulous effervescent beverage that is said to have several curative effects. In addition to sugar, the beverage contains small amounts of alcohol and various acids, including acetic acid, gluconic acid and lactic acid, as well as some antibiotic substances. To characterize the yeast spectrum with special consideration given to facultatively pathogenic yeasts, two commercially available specimens of tea fungus and 32 from private households in Germany were analysed by micromorphological and biochemical methods. Yeasts of the genera Brettanomyces, Zygosaccharomyces and Saccharomyces were identified in 56%, 29% and 26% respectively. The species Saccharomycodes ludwigii and Candida kefyr were only demonstrated in isolated cases. Furthermore, the tests revealed pellicle-forming yeasts such as Candida krusei or Issatchenkia orientalis/occidentalis as well as species of the apiculatus yeasts (Kloeckera, Hanseniaspora). Thus, the genus Brettanomyces may be a typical group of yeasts that are especially adapted to the environment of the tea fungus. However, to investigate further the beneficial effects of tea fungus, a spectrum of the other typical genera must be defined. Only three specimens showed definite contaminations. In one case, no yeasts could be isolated because of massive contamination with Penicillium spp. In the remaining two samples (from one household), Candida albicans was demonstrated. The low rate of contamination might be explained by protective mechanisms, such as formation of organic acids and antibiotic substances. Thus, subjects with a healthy metabolism do not need to be advised against cultivating Kombucha. However, those suffering from immunosuppression should preferably

  15. Proton Pumping of the Yeast Plasma Membrane H+-ATPase

    DTIC Science & Technology

    1993-08-16

    function of the yeast plasma membrane H+- ATPase. This ATPase is a P-type cation transporter composed of a single protein of 100,000 Da molecular...August 16, 1993 ] Final 25 Sep 89 - 14 May 94 / 4. TITLE AND SUBTITLE S UDN UBR Proton Pumping of the Yeast Plasma Membrane HW-AT~ase G. AUTOR(S)DAALO3...Maximum 200 words) This proposal was to study the structure and function of the yeast plasma membrane H+-ATPase. We I proposed to study I )the

  16. Mediated amperometry reveals different modes of yeast responses to sugars.

    PubMed

    Garjonyte, Rasa; Melvydas, Vytautas; Malinauskas, Albertas

    2016-02-01

    Menadione-mediated amperometry at carbon paste electrodes modified with various yeasts (Saccharomyces cerevisiae, Candida pulcherrima, Pichia guilliermondii and Debaryomyces hansenii) was employed to monitor redox activity inside the yeast cells induced by glucose, fructose, sucrose, maltose or galactose. Continuous measurements revealed distinct modes (transient or gradually increasing) of the current development during the first 2 to 3 min after subjection to glucose, fructose and sucrose at electrodes containing S. cerevisiae and non-Saccharomyces strains. Different modes (increasing or decreasing) of the current development after yeast subjection to galactose at electrodes with S. cerevisiae or D. hansenii and at electrodes with C. pulcherrima and P. guilliermondii suggested different mechanisms of galactose assimilation.

  17. How do yeast cells become tolerant to high ethanol concentrations?

    PubMed

    Snoek, Tim; Verstrepen, Kevin J; Voordeckers, Karin

    2016-08-01

    The brewer's yeast Saccharomyces cerevisiae displays a much higher ethanol tolerance compared to most other organisms, and it is therefore commonly used for the industrial production of bioethanol and alcoholic beverages. However, the genetic determinants underlying this yeast's exceptional ethanol tolerance have proven difficult to elucidate. In this perspective, we discuss how different types of experiments have contributed to our understanding of the toxic effects of ethanol and the mechanisms and complex genetics underlying ethanol tolerance. In a second part, we summarize the different routes and challenges involved in obtaining superior industrial yeasts with improved ethanol tolerance.

  18. Occurrence and function of yeasts in Asian indigenous fermented foods.

    PubMed

    Aidoo, Kofi E; Nout, M J Rob; Sarkar, Prabir K

    2006-01-01

    In the Asian region, indigenous fermented foods are important in daily life. In many of these foods, yeasts are predominant and functional during the fermentation. The diversity of foods in which yeasts predominate ranges from leavened bread-like products such as nan and idli, to alcoholic beverages such as rice and palm wines, and condiments such as papads and soy sauce. Although several products are obtained by natural fermentation, the use of traditional starter cultures is widespread. This minireview focuses on the diversity and functionality of yeasts in these products, and on opportunities for research and development.

  19. Characterization of Septin Ultrastructure in Budding Yeast Using Electron Tomography

    PubMed Central

    Bertin, Aurélie; Nogales, Eva

    2015-01-01

    Summary Septins are essential for the completion of cytokinesis. In budding yeast, Saccharomyces cerevisiae, septins are located at the bud neck during mitosis and are closely connected to the inner plasma membrane. In vitro, yeast septins have been shown to self-assemble into a variety of filamentous structures, including rods, paired filaments, bundles and rings [1–3]. Using electron tomography of freeze-substituted section and cryo-electron tomography of frozen sections, we determined the three dimensional organization of the septin cytoskeleton in dividing budding yeast with molecular resolution [4,5]. Here we describe the detailed procedures used for our characterization of the septin cellular ultrastructure. PMID:26519309

  20. The roles of thiol oxidoreductases in yeast replicative aging.

    PubMed

    Hacioglu, Elise; Esmer, Isil; Fomenko, Dmitri E; Gladyshev, Vadim N; Koc, Ahmet

    2010-01-01

    Thiol-based redox reactions are involved in the regulation of a variety of biological functions, such as protection against oxidative stress, signal transduction and protein folding. Some proteins involved in redox regulation have been shown to modulate life span in organisms from yeast to mammals. To assess the role of thiol oxidoreductases in aging on a genome-wide scale, we analyzed the replicative life span of yeast cells lacking known and candidate thiol oxidoreductases. The data suggest the role of several pathways in controlling yeast replicative life span, including thioredoxin reduction, protein folding and degradation, peroxide reduction, PIP3 signaling, and ATP synthesis.

  1. The complex and dynamic genomes of industrial yeasts.

    PubMed

    Querol, Amparo; Bond, Ursula

    2009-04-01

    The Saccharomyces sensu stricto genus contains many species that are industrially important for fermentation of wines, beers and ales. The molecular characterization of the genomes of yeasts involved in these processes reveals that the majority arose from interspecific hybridization between two and sometimes three yeast species. The hybridization events generated allopolyploid genomes, and subsequent recombination events between the parental genomes resulted in the formation of mosaic chromosomes. The polyploid and hybrid nature of the genomes confers robust characteristics such as tolerance to environmental stress to these industrial yeasts and provides a means for adaptive evolution.

  2. Media composition influences yeast one- and two-hybrid results.

    PubMed

    Liu, Ying; Merchant, Zabeena; Hsiao, Hao-Ching; Gonzalez, Kim L; Matthews, Kathleen S; Bondos, Sarah E

    2011-08-15

    Although yeast two-hybrid experiments are commonly used to identify protein interactions, the frequent occurrence of false negatives and false positives hampers data interpretation. Using both yeast one-hybrid and two-hybrid experiments, we have identified potential sources of these problems: the media preparation protocol and the source of the yeast nitrogen base may not only impact signal range but also effect whether a result appears positive or negative. While altering media preparation may optimize signal differences for individual experiments, media preparation must be reported in detail to replicate studies and accurately compare results from different experiments.

  3. PMAA-stabilized ferrofluid/chitosan/yeast composite for bioapplications

    NASA Astrophysics Data System (ADS)

    Baldikova, Eva; Prochazkova, Jitka; Stepanek, Miroslav; Hajduova, Jana; Pospiskova, Kristyna; Safarikova, Mirka; Safarik, Ivo

    2017-04-01

    A simple, one-pot process for the preparation of magnetically responsive yeast-based biocatalysts was developed. Saccharomyces cerevisiae, Candida utilis and Kluyveromyces lactis cells were successfully incorporated into chitosan gel magnetically modified with poly(methacrylic acid)-stabilized magnetic fluid (PMAA-FF) during its formation. Magnetic PMAA-FF/chitosan/yeast composites were efficiently employed for invert sugar production. The dependence of invertase activity on used yeast, amount of magnetic biocatalyst, agitation time and after reuse was studied in detail. The tested magnetic biocatalysts retained at least 69% of their initial activity after 8 reuse cycles.

  4. Differential Adsorption of Ochratoxin A and Anthocyanins by Inactivated Yeasts and Yeast Cell Walls during Simulation of Wine Aging

    PubMed Central

    Petruzzi, Leonardo; Baiano, Antonietta; De Gianni, Antonio; Sinigaglia, Milena; Corbo, Maria Rosaria; Bevilacqua, Antonio

    2015-01-01

    The adsorption of ochratoxin A (OTA) by yeasts is a promising approach for the decontamination of musts and wines, but some potential competitive or interactive phenomena between mycotoxin, yeast cells, and anthocyanins might modify the intensity of the phenomenon. The aim of this study was to examine OTA adsorption by two strains of Saccharomyces cerevisiae (the wild strain W13, and the commercial isolate BM45), previously inactivated by heat, and a yeast cell wall preparation. Experiments were conducted using Nero di Troia red wine contaminated with 2 μg/L OTA and supplemented with yeast biomass (20 g/L). The samples were analyzed periodically to assess mycotoxin concentration, chromatic characteristics, and total anthocyanins over 84 days of aging. Yeast cell walls revealed the highest OTA-adsorption in comparison to thermally-inactivated cells (50% vs. 43% toxin reduction), whilst no significant differences were found for the amount of adsorbed anthocyanins in OTA-contaminated and control wines. OTA and anthocyanins adsorption were not competitive phenomena. Unfortunately, the addition of yeast cells to wine could cause color loss; therefore, yeast selection should also focus on this trait to select the best strain. PMID:26516913

  5. Yeasts for Global Happiness: report of the 14th International Congress on Yeasts (ICY14) held in Awaji Island.

    PubMed

    Watanabe, Daisuke; Takagi, Hiroshi

    2017-02-01

    The 14th International Congress on Yeasts (ICY14) was held at Awaji Yumebutai International Conference Center (Awaji, Hyogo) in Japan from 11 to 15 September 2016. The main slogan of ICY14 was 'Yeasts for Global Happiness', which enabled us to acknowledge the high-potential usefulness of yeasts contributing to the global happiness in terms of food/beverage, health/medicine and energy/environment industries, as well as to basic biosciences. In addition, two more concepts were introduced: 'from Japan to the world' and 'from senior to junior'. As it was the first ICY meeting held in Japan or other Asian countries, ICY14 provided a good opportunity to widely spread the great achievements by Japanese and Asian yeast researchers, such as those by the 2016 Nobel Laureate Dr. Yoshinori Ohsumi, and also, to convey the fun and importance of yeasts to the next generation of researchers from Asia and all over the world. As a result, a total of 426 yeast lovers from 42 countries (225 overseas and 201 domestic participants) with different generations attended ICY14 to share the latest knowledge of a wide range of yeast research fields and to join active and constructive scientific discussions.

  6. Construction of a large synthetic human Fab antibody library on yeast cell surface by optimized yeast mating.

    PubMed

    Baek, Du-San; Kim, Yong-Sung

    2014-03-28

    Yeast surface-displayed antibody libraries provide an efficient and quantitative screening resource for given antigens, but suffer from typically modest library sizes owing to low yeast transformation efficiency. Yeast mating is an attractive method for overcoming the limit of yeast transformation to construct a large, combinatorial antibody library, but the optimal conditions have not been reported. Here, we report a large synthetic human Fab (antigen binding fragment) yeast surface-displayed library generated by stepwise optimization of yeast mating conditions. We first constructed HC (heavy chain) and LC (light chain) libraries, where all of the six CDRs (complementarity-determining regions) of the variable domains were diversified mimicking the human germline antibody repertoires by degenerate codons, onto single frameworks of VH3-23 and Vkappa1-16 germline sequences, in two haploid cells of opposite mating types. Yeast mating conditions were optimized in the order of cell density, media pH, and cell growth phase, yielding a mating efficiency of ~58% between the two haploid cells carrying HC and LC libraries. We constructed two combinatorial Fab libraries with CDR-H3 of 9 or 11 residues in length with colony diversities of more than 10(9) by one round of yeast mating between the two haploid HC and LC libraries, with modest diversity sizes of ~10(7). The synthetic human Fab yeast-displayed libraries exhibited relative amino acid compositions in each position of the six CDRs that were very similar to those of the designed repertoires, suggesting that they are a promising source for human Fab antibody screening.

  7. A yeast screen system for aromatase inhibitors and ligands for androgen receptor: yeast cells transformed with aromatase and androgen receptor.

    PubMed

    Mak, P; Cruz, F D; Chen, S

    1999-11-01

    Endocrine disruptors are hormone mimics that modify hormonal action in humans and animals. It is thought that some endocrine disruptors modify estrogen and androgen action in humans and animals by suppressing aromatase activity. Aromatase cytochrome P450 is the key enzyme that converts C19 androgens to aromatic C18 estrogenic steroids. We have developed a novel aromatase inhibitor screening method that allows us to identify antiaromatase activity of various environmental chemicals. The screen was developed by coexpressing the human aromatase and the mouse androgen receptor in yeast cells, which carry the androgen-responsive ss-galactosidase reporter plasmid. Functional expression of aromatase in yeast has been demonstrated using the [3H]-water release assay with intact cells as well as with yeast microsomes. The aromatase activity could be blocked by known aromatase inhibitors such as aminoglutethimide (AG). Yeast-produced androgen receptors were able to transactivate a yeast basal promoter linked to an androgen-responsive element in response to androgens. The resultant triple yeast transformant responded to the treatment of testosterone, androstenedione, or 5 alpha-dihydrotestosterone (5 alpha-DHT). In the absence of the aromatase inhibitor AG, transcriptional activation was observed only for the nonaromatizable androgen 5 alpha-DHT. However, the two aromatizable androgens (testosterone and androstenedione) induced the reporter activity in the presence of AG. Using this yeast-based assay, we confirmed that two flavones, chrysin and alpha-naphtholflavone, are inhibitors of aromatase. Thus, this yeast system allows us to develop a high-throughput screening method, without using radioactive substrate, to identify aromatase inhibitors as well as new ligands (nonaromatizable androgen mimics) for the androgen receptors. In addition, this screening method also allows us to distinguish nonandrogenic aromatase inhibitors from inhibitors with androgenic activity. This yeast

  8. Organoleptic Analysis of Doughs Fermented with Yeasts From A Nigerian Palm Wine (Elaeis guineensis) and Certain Commercial Yeasts

    PubMed Central

    B, Boboye; I, Dayo-Owoyemi; F. A, Akinyosoye

    2008-01-01

    Yeasts isolated from a freshly tapped palm wine obtained from Akure, Nigeria were identified as Schizosaccharomyces pombe, Saccharomyces cerevisiae, Debaryomyces hansenii, Geotrichum lactis and Zygosaccharomyces rouxii. Each of the isolates was used to ferment wheat flour dough and baked. Sensory analysis of the doughs was carried out on leavening, texture, aroma, taste and appearance. Saccharomyces cerevisiae performed best in leavening the dough while Debaryomyces hansenii produced doughs with the best taste and aroma. Appearances of the doughs made with all the isolated yeasts did not differ significantly (P<0.05) from that of the dough that lacked yeast. PMID:19088921

  9. Organoleptic Analysis of Doughs Fermented with Yeasts From A Nigerian Palm Wine (Elaeis guineensis) and Certain Commercial Yeasts.

    PubMed

    I, Dayo-Owoyemi; B, Boboye; Fa, Akinyosoye

    2008-01-01

    Yeasts isolated from a freshly tapped palm wine obtained from Akure, Nigeria were identified as Schizosaccharomyces pombe, Saccharomyces cerevisiae, Debaryomyces hansenii, Geotrichum lactis and Zygosaccharomyces rouxii. Each of the isolates was used to ferment wheat flour dough and baked. Sensory analysis of the doughs was carried out using leavening, texture, aroma, taste and appearance. Saccharomyces cerevisiae performed best in leavening the dough while Debaryomyces hansenii produced doughs with the best taste and aroma. Appearances of the doughs made with all the isolated yeasts did not differ significantly (P>0.05) from that of the dough that lacked yeast.

  10. Nuclear membrane: nuclear envelope PORosity in fission yeast meiosis.

    PubMed

    Sazer, Shelley

    2010-11-09

    The fission yeast Schizosaccharomyces pombe undergoes closed mitosis but 'virtual nuclear envelope breakdown' at anaphase of meiosis II, in which the nuclear envelope is structurally closed but functionally open.

  11. Mathematical model of sugar uptake in fermenting yeasted dough.

    PubMed

    Loveday, S M; Winger, R J

    2007-07-25

    Fermentation prior to freezing significantly reduces the shelf life of frozen dough, measured as a decline in proofing power. Changes during fermentation caused by yeast metabolism have previously been described empirically on a dough weight basis and have not been mathematically modeled. In this work, yeast metabolites were quantified in fermenting dough and their concentrations were estimated in the aqueous environment around yeast cells. The osmotic pressure in the aqueous phase increases by 23% during 3 h of fermentation, which depresses the freezing point by 1 degrees C. The rise in osmotic pressure and the accumulation of ethanol may affect phase equilibria in the dough, baking properties, and the shelf life of frozen dough. Predictive modeling equations fitted sugar concentration data accurately. It was found that the preference of baker's yeast for glucose over fructose was stronger in fermenting dough than in liquid fermentations. The usefulness of the model in industrial bakery formulation work was demonstrated.

  12. A panoramic view of yeast noncoding RNA processing.

    PubMed

    Peng, Wen Tao; Robinson, Mark D; Mnaimneh, Sanie; Krogan, Nevan J; Cagney, Gerard; Morris, Quaid; Davierwala, Armaity P; Grigull, Jörg; Yang, Xueqi; Zhang, Wen; Mitsakakis, Nicholas; Ryan, Owen W; Datta, Nira; Jojic, Vladimir; Pal, Chris; Canadien, Veronica; Richards, Dawn; Beattie, Bryan; Wu, Lani F; Altschuler, Steven J; Roweis, Sam; Frey, Brendan J; Emili, Andrew; Greenblatt, Jack F; Hughes, Timothy R

    2003-06-27

    Predictive analysis using publicly available yeast functional genomics and proteomics data suggests that many more proteins may be involved in biogenesis of ribonucleoproteins than are currently known. Using a microarray that monitors abundance and processing of noncoding RNAs, we analyzed 468 yeast strains carrying mutations in protein-coding genes, most of which have not previously been associated with RNA or RNP synthesis. Many strains mutated in uncharacterized genes displayed aberrant noncoding RNA profiles. Ten factors involved in noncoding RNA biogenesis were verified by further experimentation, including a protein required for 20S pre-rRNA processing (Tsr2p), a protein associated with the nuclear exosome (Lrp1p), and a factor required for box C/D snoRNA accumulation (Bcd1p). These data present a global view of yeast noncoding RNA processing and confirm that many currently uncharacterized yeast proteins are involved in biogenesis of noncoding RNA.

  13. Biodiversity of brewery yeast strains and their fermentative activities.

    PubMed

    Berlowska, Joanna; Kregiel, Dorota; Rajkowska, Katarzyna

    2015-01-01

    We investigated the genetic, biochemical, fermentative and physiological characteristics of brewery yeast strains and performed a hierarchical cluster analysis to evaluate their similarity. We used five different ale and lager yeast strains, originating from different European breweries and deposited at the National Collection of Yeast Cultures (UK). Ale and lager strains exhibited different genomic properties, but their assimilation profiles and pyruvate decarboxylase activities corresponded to their species classifications. The activity of another enzyme, succinate dehydrogenase, varied between different brewing strains. Our results confirmed that ATP and glycogen content, and the activity of the key metabolic enzymes succinate dehydrogenase and pyruvate decarboxylase, may be good general indicators of cell viability. However, the genetic properties, physiology and fermentation capacity of different brewery yeasts are unique to individual strains.

  14. Comparative study on the identification of food-borne yeasts.

    PubMed Central

    Török, T; King, A D

    1991-01-01

    Morphologically distinct yeast colonies from partially and fully processed fruits and vegetables were isolated over a 3-year period. Identification of 239 strains was achieved by using standard methods, commercial identification kits (API 20C and API YEAST-IDENT), and a simplified system for food-borne yeasts. The identified strains of fruit origin represented 36 species belonging to 19 genera. Among strains of vegetable origin, 34 species representing 17 genera were identified. The simplified identification system and the conventional method provided the same results in 80% of the cases. The commercial identification kits were easy to use but were not appropriate for food-borne yeast species. Computer-assisted identification was helpful. PMID:2059042

  15. Baker's yeast assay procedure for testing heavy metal toxicity

    SciTech Connect

    Bitton, G.; Koopman, B.; Wang, H.D.

    1984-01-01

    Baker's yeast (Saccharomyces cerevisiae) is microorganism which is commercially available and sold as packaged dry pellets in any food store at low cost. Studies have been undertaken on the effects of organic xenobiotics as well as heavy metals on yeast metabolism. This type of study has been generally useful in examining the mechanism(s) of chemical toxicity. However, a rapid and quantitative toxicity test using S. cerevisiae as the test organism has not been developed. The purpose of this study was to develop a toxicity assay for heavy metals, using commercial dry yeast as the test microorganism. This rapid and simple procedure is based on the reduction of 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride (INT) to INT-formazan by the yeast electron transport system. The scoring of active cells following exposure to heavy metals was undertaken according to the MINT (malachite green-INT) method developed by Bitton and Koopman.

  16. An Analysis of Interference in the Fission Yeast Schizosaccharomyces Pombe

    PubMed Central

    Munz, P.

    1994-01-01

    The evaluation of three-point crosses at the tetrad and random spore level leads to the conclusion that both chiasma and chromatid interference are absent in the fission yeast Schizosaccharomyces pombe. PMID:8088515

  17. Domestication and Divergence of Saccharomyces cerevisiae Beer Yeasts.

    PubMed

    Gallone, Brigida; Steensels, Jan; Prahl, Troels; Soriaga, Leah; Saels, Veerle; Herrera-Malaver, Beatriz; Merlevede, Adriaan; Roncoroni, Miguel; Voordeckers, Karin; Miraglia, Loren; Teiling, Clotilde; Steffy, Brian; Taylor, Maryann; Schwartz, Ariel; Richardson, Toby; White, Christopher; Baele, Guy; Maere, Steven; Verstrepen, Kevin J

    2016-09-08

    Whereas domestication of livestock, pets, and crops is well documented, it is still unclear to what extent microbes associated with the production of food have also undergone human selection and where the plethora of industrial strains originates from. Here, we present the genomes and phenomes of 157 industrial Saccharomyces cerevisiae yeasts. Our analyses reveal that today's industrial yeasts can be divided into five sublineages that are genetically and phenotypically separated from wild strains and originate from only a few ancestors through complex patterns of domestication and local divergence. Large-scale phenotyping and genome analysis further show strong industry-specific selection for stress tolerance, sugar utilization, and flavor production, while the sexual cycle and other phenotypes related to survival in nature show decay, particularly in beer yeasts. Together, these results shed light on the origins, evolutionary history, and phenotypic diversity of industrial yeasts and provide a resource for further selection of superior strains. PAPERCLIP.

  18. Inhibition of the growth of yeasts in fermented salads.

    PubMed

    Bonestroo, M H; de Wit, J C; Kusters, B J; Rombouts, F M

    1993-02-01

    Salads composed of vegetables and/or meat in an oil-in-water emulsion were prepared by fermentation for 7 h at 42 degrees C or 45 degrees C with strains of Lactobacillus spp. Their stability towards spoilage yeasts was studied using Saccharomyces cerevisiae, Saccharomyces exiguus and Torulaspora delbrueckii, isolated from salads, as well as Pichia membranaefaciens and Zygosaccharomyces bailii. Salads fermented with good lactic starters usually had pH values of < or = 4.2 and lactic acid concentrations of 0.28 to 0.43% (w/w). High numbers of spoilage yeasts (and production of large volumes of CO2) were not attained in these salads, provided the initial concentration of spoilage yeasts was sufficiently low (< or = 100 CFU/g). Inhibition of spoilage yeasts in lactic fermented salads is probably due to lactic acid, the low storage temperature and the low residual oxygen concentration.

  19. Protein transmission during Dean vortex microfiltration of yeast suspensions.

    PubMed

    Kluge, T; Rezende, C; Wood, D; Belfort, G

    1999-12-20

    Substantially higher rates of protein and fluid volume transport for microfiltration of yeast suspensions were possible with improved hydrodynamics using centrifugal fluid instabilities called Dean vortices. Under constant permeate flux operation with suspended yeast cells, a helical module exhibited 19 times the filtration capacity of a linear module. For feed containing both BSA and beer yeast under constant transmembrane pressure with diafiltration, about twice as much protein (BSA and other proteins from cell lysis) was transported out of the feed by the helical module as compared with the linear module. The volumetric permeation flux improvements for the helical over the linear module ranged from 18 to 43% for yeast concentrations up to 4.5 dry wt %.

  20. Oxidative Stress and Programmed Cell Death in Yeast

    PubMed Central

    Farrugia, Gianluca; Balzan, Rena

    2012-01-01

    Yeasts, such as Saccharomyces cerevisiae, have long served as useful models for the study of oxidative stress, an event associated with cell death and severe human pathologies. This review will discuss oxidative stress in yeast, in terms of sources of reactive oxygen species (ROS), their molecular targets, and the metabolic responses elicited by cellular ROS accumulation. Responses of yeast to accumulated ROS include upregulation of antioxidants mediated by complex transcriptional changes, activation of pro-survival pathways such as mitophagy, and programmed cell death (PCD) which, apart from apoptosis, includes pathways such as autophagy and necrosis, a form of cell death long considered accidental and uncoordinated. The role of ROS in yeast aging will also be discussed. PMID:22737670

  1. Mitochondrial inheritance in budding yeasts: towards an integrated understanding.

    PubMed

    Solieri, Lisa

    2010-11-01

    Recent advances in yeast mitogenomics have significantly contributed to our understanding of the diversity of organization, structure and topology in the mitochondrial genome of budding yeasts. In parallel, new insights on mitochondrial DNA (mtDNA) inheritance in the model organism Saccharomyces cerevisiae highlighted an integrated scenario where recombination, replication and segregation of mtDNA are intricately linked to mitochondrial nucleoid (mt-nucleoid) structure and organelle sorting. In addition to this, recent discoveries of bifunctional roles of some mitochondrial proteins have interesting implications on mito-nuclear genome interactions and the relationship between mtDNA inheritance, yeast fitness and speciation. This review summarizes the current knowledge on yeast mitogenomics, mtDNA inheritance with regard to mt-nucleoid structure and organelle dynamics, and mito-nuclear genome interactions.

  2. Dissecting principles governing actin assembly using yeast extracts.

    PubMed

    Michelot, Alphée; Drubin, David G

    2014-01-01

    In this chapter, we describe recent protocols that we have developed to trigger actin assembly and actin-based motility in yeast cell extracts. Our method allows for the fast preparation of yeast extracts that are competent in dynamic assembly of distinct actin filament structures of biologically appropriate protein composition. Compared to previous extract-based systems using other eukaryotic cell types, yeast provides a unique advantage for combining reconstituted assays with the preparation of extracts from genetically modified yeast strains. We present a global strategy for dissecting the functions of individual proteins, where the activities of the proteins are analyzed in systems of variable complexity, ranging from simple mixtures of pure proteins to the full complexity of a cell's cytoplasm.

  3. [Overexpression of FKS1 to improve yeast autolysis-stress].

    PubMed

    Li, Jia; Wang, Jinjing; Li, Qi

    2015-09-01

    With the development of high gravity brewing, yeast cells are exposed to multiple brewing-associated stresses, such as increased osmotic pressure, enhanced alcohol concentration and nutritional imbalance. These will speed up yeast autolysis, which seriously influence beer flavor and quality. To increase yeast anti-autolytic ability, FKS1 overexpression strain was constructed by 18S rDNA. The concentration of β-1,3-glucan of overexpression strain was 62% higher than that of wild type strain. Meantime, FKS1 overexpression strain increased anti-stress ability at 8% ethanol, 0.4 mol/L NaCl and starvation stress. Under simulated autolysis, FKS1 showed good anti-autolytic ability by slower autolysis. These results confirms the potential of FKS1 overexpression to tackle yeast autolysis in high-gravity brewing.

  4. Production of a yeast artificial chromosome for stable expression of a synthetic xylose isomerase-xylulokinase polyprotein in a fuel ethanol yeast strain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Commercialization of fuel ethanol production from lignocellulosic biomass has focused on engineering the glucose-fermenting industrial yeast Saccharomyces cerevisiae to utilize pentose sugars. A yeast artificial chromosome (YAC) was engineered to contain a polyprotein gene construct expressing xylos...

  5. Determination of Glucose Concentration in Yeast Culture Medium

    NASA Astrophysics Data System (ADS)

    Hara, Seiichi; Kishimoto, Tomokazu; Muraji, Masafumi; Tsujimoto, Hiroaki; Azuma, Masayuki; Ooshima, Hiroshi

    The present paper describes a sensor for measuring the glucose concentration of yeast culture medium. The sensor determines glucose concentration by measuring the yield of hydrogen peroxide produced by glucose oxidase, which is monitored as luminescence using photomultiplier. The present sensor is able to measure low glucose concentration in media in which yeast cells keep respiration state. We herein describe the system and the characteristics of the glucose sensor.

  6. A new specific DNA endonuclease activity in yeast mitochondria.

    PubMed

    Sargueil, B; Delahodde, A; Hatat, D; Tian, G L; Lazowska, J; Jacq, C

    1991-02-01

    Two group I intron-encoded proteins from the yeast mitochondrial genome have already been shown to have a specific DNA endonuclease activity. This activity mediates intron insertion by cleaving the DNA sequence corresponding to the splice junction of an intronless strain. We have discovered in mitochondrial extracts from the yeast strain 777-3A a new DNA endonuclease activity which cleaves the fused exon A3-exon A4 junction sequence of the CO XI gene.

  7. [Studies on the assimilation of inorganic selenium by yeast].

    PubMed

    Xie, L; Ouyang, Z; Xie, X

    1990-02-01

    In the process of assimilation of inorganic selenium by yeast to the organic-selenium, some rules on the relation of the kinds of culture medium, concentration of sodium selenite and methionine to the total selenium and selenomethionine content in the yeast formed have been found; and a new, accurate procedure--modified acid hydrolysis-ion exchange chromatography for determining the content of seleno-amino acid in biological materials has been established.

  8. Kinetics of growth and sugar consumption in yeasts.

    PubMed

    van Dijken, J P; Weusthuis, R A; Pronk, J T

    1993-01-01

    An overview is presented of the steady- and transient state kinetics of growth and formation of metabolic byproducts in yeasts. Saccharomyces cerevisiae is strongly inclined to perform alcoholic fermentation. Even under fully aerobic conditions, ethanol is produced by this yeast when sugars are present in excess. This so-called 'Crabtree effect' probably results from a multiplicity of factors, including the mode of sugar transport and the regulation of enzyme activities involved in respiration and alcoholic fermentation. The Crabtree effect in S. cerevisiae is not caused by an intrinsic inability to adjust its respiratory activity to high glycolytic fluxes. Under certain cultivation conditions, for example during growth in the presence of weak organic acids, very high respiration rates can be achieved by this yeast. S. cerevisiae is an exceptional yeast since, in contrast to most other species that are able to perform alcoholic fermentation, it can grow under strictly anaerobic conditions. 'Non-Saccharomyces' yeasts require a growth-limiting supply of oxygen (i.e. oxygen-limited growth conditions) to trigger alcoholic fermentation. However, complete absence of oxygen results in cessation of growth and therefore, ultimately, of alcoholic fermentation. Since it is very difficult to reproducibly achieve the right oxygen dosage in large-scale fermentations, non-Saccharomyces yeasts are therefore not suitable for large-scale alcoholic fermentation of sugar-containing waste streams. In these yeasts, alcoholic fermentation is also dependent on the type of sugar. For example, the facultatively fermentative yeast Candida utilis does not ferment maltose, not even under oxygen-limited growth conditions, although this disaccharide supports rapid oxidative growth.

  9. Opportunistic yeast infections: candidiasis, cryptococcosis, trichosporonosis and geotrichosis.

    PubMed

    Vázquez-González, Denisse; Perusquía-Ortiz, Ana María; Hundeiker, Max; Bonifaz, Alexandro

    2013-05-01

    Opportunistic yeast infections are diseases caused by fungi which normally are saprophytic and do not cause disease in humans or animals. The prevalence of these diseases has been increasing due to immunosuppressive, corticosteroid, and long-term antibiotic treatment following organ transplantation or after serious metabolic, hematological, or immunological diseases. We review epidemiological, clinical, diagnostic, and therapeutic aspects of the four "big" opportunistic yeast infections: candidiasis, cryptococcosis, trichosporonosis, and geotrichosis.

  10. [Treatment of drilling wastewater from oil field by using yeast].

    PubMed

    Wang, Yanming; Yang, Min; Zheng, Shaokui; Zhou, Xiangyu; Shen, Zhemin

    2002-09-01

    Two strains of yeast, namely Wickerhamiella domercqii and Candida boidinii, were acquired through screening from soil samples contaminated by drilling wastewater. A TOC removal of 40.5% was acquired when the mixture of the two yeast strains was used for drilling wastewater treatment, a little higher than that with activated sludge acclimated with wastewater (35.2%). Some organic compounds in the fraction of molecular weight above 60,000 were found to be biodegradable.

  11. Antifungal Susceptibility Testing of Ascomycetous Yeasts Isolated from Animals

    PubMed Central

    Álvarez-Pérez, Sergio; García, Marta E.; Peláez, Teresa; Martínez-Nevado, Eva

    2016-01-01

    Recent studies suggest that antifungal resistance in yeast isolates of veterinary origin may be an underdiagnosed threat. We tested a collection of 92 ascomycetous yeast isolates that were obtained in Spain from birds, mammals and insects for antifungal susceptibility. MICs to amphotericin B and azoles were low, and no resistant isolates were detected. Despite these results, and given the potential role of animals as reservoirs of resistant strains, continuous monitoring of antifungal susceptibility in the veterinary setting is recommended. PMID:27216048

  12. Yeast Infection and Diabetes Mellitus among Pregnant Mother in Malaysia

    PubMed Central

    Sopian, Iylia Liyana; Shahabudin, Sa’adiah; Ahmed, Mowaffaq Adam; Lung, Leslie Than Thian; Sandai, Doblin

    2016-01-01

    Background Vaginal yeast infection refers to irritation of the vagina due to the presence of opportunistic yeast of the genus Candida (mostly Candida albicans). About 75% of women will have at least one episode of vaginal yeast infection during their lifetime. Several studies have shown that pregnancy and uncontrolled diabetes increase the infection risk. Reproductive hormone fluctuations during pregnancy and elevated glucose levels characteristic of diabetes provide the carbon needed for Candida overgrowth and infection. The goal of this study was to determine the prevalence of vaginal yeast infection among pregnant women with and without diabetes. Methods This was a case-control study using cases reports from Kepala Batas Health Clinic, Penang State, Malaysia from 2006 to 2012. In total, 740 pregnant ladies were chosen as sample of which 370 were diabetic and 370 were non-diabetic cases. Results No relationship between diabetes and the occurrence of vaginal yeast infection in pregnant women was detected, and there was no significant association between infection and age group, race or education level. Conclusion In conclusion, within radius of this study, vaginal yeast infection can occur randomly in pregnant women. PMID:27540323

  13. Immobilisation increases yeast cells' resistance to dehydration-rehydration treatment.

    PubMed

    Borovikova, Diana; Rozenfelde, Linda; Pavlovska, Ilona; Rapoport, Alexander

    2014-08-20

    This study was performed with the goal of revealing if the dehydration procedure used in our new immobilisation method noticeably decreases the viability of yeast cells in immobilised preparations. Various yeasts were used in this research: Saccharomyces cerevisiae cells that were rather sensitive to dehydration and had been aerobically grown in an ethanol-containing medium, a recombinant strain of S. cerevisiae grown in aerobic conditions which were completely non-resistant to dehydration and an anaerobically grown bakers' yeast strain S. cerevisiae, as well as a fairly resistant Pichia pastoris strain. Experiments performed showed that immobilisation of all these strains essentially increased their resistance to a dehydration-rehydration treatment. The increase of cells' viability (compared with control cells dehydrated in similar conditions) was from 30 to 60%. It is concluded that a new immobilisation method, which includes a dehydration stage, does not lead to an essential loss of yeast cell viability. Correspondingly, there is no risk of losing the biotechnological activities of immobilised preparations. The possibility of producing dry, active yeast preparations is shown, for those strains that are very sensitive to dehydration and which can be used in biotechnology in an immobilised form. Finally, the immobilisation approach can be used for the development of efficient methods for the storage of recombinant yeast strains.

  14. Optimization of killer assays for yeast selection protocols.

    PubMed

    Lopes, C A; Sangorrín, M P

    2010-01-01

    A new optimized semiquantitative yeast killer assay is reported for the first time. The killer activity of 36 yeast isolates belonging to three species, namely, Metschnikowia pulcherrima, Wickerhamomyces anomala and Torulaspora delbrueckii, was tested with a view to potentially using these yeasts as biocontrol agents against the wine spoilage species Pichia guilliermondii and Pichia membranifaciens. The effectiveness of the classical streak-based (qualitative method) and the new semiquantitative techniques was compared. The percentage of yeasts showing killer activity was found to be higher by the semiquantitative technique (60%) than by the qualitative method (45%). In all cases, the addition of 1% NaCl into the medium allowed a better observation of the killer phenomenon. Important differences were observed in the killer capacity of different isolates belonging to a same killer species. The broadest spectrum of action was detected in isolates of W. anomala NPCC 1023 and 1025, and M. pulcherrima NPCC 1009 and 1013. We also brought experimental evidence supporting the importance of the adequate selection of the sensitive isolate to be used in killer evaluation. The new semiquantitative method proposed in this work enables to visualize the relationship between the number of yeasts tested and the growth of the inhibition halo (specific productivity). Hence, this experimental approach could become an interesting tool to be taken into account for killer yeast selection protocols.

  15. Psychrophilic yeasts in glacial environments of Alpine glaciers.

    PubMed

    Turchetti, Benedetta; Buzzini, Pietro; Goretti, Marta; Branda, Eva; Diolaiuti, Guglielmina; D'Agata, Carlo; Smiraglia, Claudio; Vaughan-Martini, Ann

    2008-01-01

    The presence of psychrophilic yeasts in supra- and subglacial sediments, ice and meltwater collected from two glaciers of the Italian Alps (Forni and Sforzellina-Ortles-Cevedale group) was investigated. After incubation at 4 degrees C, subglacial sediments contained from 1.3 x 10(3) to 9.6 x 10(3) CFU of yeasts g(-1). The number of yeast cells in supraglacial sediments was c. 10-100-fold lower. A significant proportion of isolated yeasts exhibited one or more extracellular enzymatic activities (starch-degrading, lipolytic, esterolytic, proteolytic and pectinolytic activity) at 4 degrees C. Selected isolates were able to grow at 2 degrees C under laboratory-simulated in situ conditions. In all, 106 isolated yeasts were identified by MSP-PCR fingerprinting and 26S rRNA gene sequencing of the D1/D2 region as belonging to 10 species: Aureobasidium pullulans, Cryptococcus gilvescens (over 50% of the total), Cryptococcus terricolus, Mrakia gelida, Naganishia globosa, Rhodotorula glacialis, Rhodotorula psychrophenolica, Rhodotorula bacarum, Rhodotorula creatinivora and Rhodotorula laryngis. Four strains, all belonging to a new yeast species, yet to be described, were also isolated.

  16. Advances in Gene Expression in Non-Conventional Yeasts

    NASA Astrophysics Data System (ADS)

    Nel, Sanet; Labuschagne, Michel; Albertyn, Jacobus

    Yeast has been a favoured lower eukaryotic system for the expression and production of recombinant proteins for both basic research and practical applications, and the demand for foreign-gene expression systems is increasing rapidly. Despite the vast amount of information on the molecular biology and physiology of Saccharomyces cerevisiae, which has consequently been the first choice as host system for recombinant protein production in the past, several limitations have been identified in this expression system. These limitations have recently been relieved by the development of expression systems in other yeast species known as ‘ non-conventional yeasts’ or ‘non-Saccharomyces ’ yeasts. With the increasing interest in the biotechnological applications of these yeasts in applied and fundamental studies and processes, the term ‘ non-conventional ’ yeast may well soon become redundant. As there is no universal expression system for heterologous protein production, it is necessary to recognize the merits and demerits of each system in order to make a right choice. This chapter will evaluate the competitive environment of non-conventional expression platforms represented by some of the best-known alternative yeasts systems including Kluyveromyces lactis, Yarrowia lipolytica, Hansenula polymorpha, Pichia pastoris and more recently, Arxula adeninivorans.

  17. Biochemical characterization and growth patterns of new yeast isolates.

    PubMed

    Djegui, Kadjogbé Y; Gachomo, Emma W; Hounhouigan, Djidjoho J; Kayodé, Adéchola P P; Kotchoni, Simeon O

    2014-08-01

    African sorghum opaque beers play a vital role in the diet of millions of consumers. In the current study we investigated the growth profiles of yeast strains isolated from kpete-kpete, a traditional starter used to produce tchoukoutou, an opaque sorghum beer in Benin. 10 yeast strains were isolated from sorghum beer starters and cultivated under both liquid and solid media for phenotypic growth characterization. All yeast isolates were able to grow both on solid and liquid media. Based on their growth profiles, the isolates were clustered into three groups: (i) the aggressive growth pattern (30%), (ii) the moderate growth pattern (50%), and (iii) the slow growth pattern (20%). Based on gene expression pattern, absorbance (A(600 nm)) and diameter of growth in both liquid and solid media respectively, yeast strains YK34, YK15 and YK48 were clustered in the first group, and referred to as the most aggressive growth strains, followed by group 2 (YK24, YK5, YK12, YK20, YK2) and group 3 (YK37, YK41). This growth pattern was confirmed by Invertase gene expression profiling of the yeasts showing group 1 with high level of Invertase gene expression followed by group 2 and group 3 respectively. Our results suggest that YK34, YK15 and YK48 and YK2 yeast strains constitute the best candidates in fermentation of sorghum beer production based on growth rate and assimilation of carbon and nitrogen sources.

  18. Cofilin is an essential component of the yeast cortical cytoskeleton

    PubMed Central

    1993-01-01

    We have biochemically identified the Saccharomyces cerevisiae homologue of the mammalian actin binding protein cofilin. Cofilin and related proteins isolated from diverse organisms are low molecular weight proteins (15-20 kD) that possess several activities in vitro. All bind to monomeric actin and sever filaments, and some can stably associate with filaments. In this study, we demonstrate using viscosity, sedimentation, and actin assembly rate assays that yeast cofilin (16 kD) possesses all of these properties. Cloning and sequencing of the S. cerevisiae cofilin gene (COF1) revealed that yeast cofilin is 41% identical in amino acid sequence to mammalian cofilin and, surprisingly, has homology to a protein outside the family of cofilin- like proteins. The NH2-terminal 16kD of Abp1p, a 65-kD yeast protein identified by its ability to bind to actin filaments, is 23% identical to yeast cofilin. Immunofluorescence experiments showed that, like Abp1p, cofilin is associated with the membrane actin cytoskeleton. A complete disruption of the COF1 gene was created in diploid cells. Sporulation and tetrad analysis revealed that yeast cofilin has an essential function in vivo. Although Abp1p shares sequence similarity with cofilin and has the same distribution as cofilin in the cell, multiple copies of the ABP1 gene cannot compensate for the loss of cofilin. Thus, cofilin and Abp1p are structurally related but functionally distinct components of the yeast membrane cytoskeleton. PMID:8421056

  19. The Yeast Deletion Collection: A Decade of Functional Genomics

    PubMed Central

    Giaever, Guri; Nislow, Corey

    2014-01-01

    The yeast deletion collections comprise >21,000 mutant strains that carry precise start-to-stop deletions of ∼6000 open reading frames. This collection includes heterozygous and homozygous diploids, and haploids of both MATa and MATα mating types. The yeast deletion collection, or yeast knockout (YKO) set, represents the first and only complete, systematically constructed deletion collection available for any organism. Conceived during the Saccharomyces cerevisiae sequencing project, work on the project began in 1998 and was completed in 2002. The YKO strains have been used in numerous laboratories in >1000 genome-wide screens. This landmark genome project has inspired development of numerous genome-wide technologies in organisms from yeast to man. Notable spinoff technologies include synthetic genetic array and HIPHOP chemogenomics. In this retrospective, we briefly describe the yeast deletion project and some of its most noteworthy biological contributions and the impact that these collections have had on the yeast research community and on genomics in general. PMID:24939991

  20. Detoxification of olive mill wastewaters by Moroccan yeast isolates.

    PubMed

    Ben Sassi, A; Ouazzani, N; Walker, G M; Ibnsouda, S; El Mzibri, M; Boussaid, A

    2008-06-01

    A total of 105 yeast strains were isolated from Moroccan olive oil production plants and evaluated for their ability to grow in olive oil mill wastewaters (OMW). The 9 isolates that grew best on OMW were selected for further study to evaluate their effect on removal of organic pollutants and OMW phytotoxicity (barley seed germination test). The results showed that at least four yeast isolates effectively lowered the toxicity of this effluent in addition to providing very useful materials in terms of both yeast biomass (6 g/l DW) and an irrigation fluid. This group of yeast isolates significantly reduced the concentration of total phenols (44% removal) and Chemical Oxygen Demand, COD (63% removal). The best germination rate of 80% for undiluted OMW was obtained for strain Candida holstii that also increased the pH from 4.76 to 6.75. Principal component analysis of the results obtained for the best yeast strains confirmed the importance of COD and total phenol reduction along with increase of organic nitrogen and final pH for the improvement of germination rates and phytotoxic reduction. This study has highlighted the potential of indigenous yeasts in detoxification of olive mill wastewaters.

  1. The Fermentative and Aromatic Ability of Kloeckera and Hanseniaspora Yeasts

    NASA Astrophysics Data System (ADS)

    Díaz-Montaño, Dulce M.; de Jesús Ramírez Córdova, J.

    Spontaneous alcoholic fermentation from grape, agave and others musts into an alcoholic beverage is usually characterized by the presence of several non-Saccharomyces yeasts. These genera yeasts are dominant in the early stages of the alcoholic fermentation. However the genera Hanseniaspora and Kloeckera may survive at a significant level during fermentation and can influence the chemical composition of the beverage. Several strains belonging to the species Kloeckera api-culata and Hanseniaspora guilliermondii have been extensively studied in relation to the formation of some metabolic compounds affecting the bouquet of the final product. Indeed some apiculate yeast showed positive oenological properties and their use in the alcoholic fermentations has been suggested to enhance the aroma and flavor profiles. The non- Saccharomyces yeasts have the capability to produce and secrete enzymes in the medium, such as β -glucosidases, which release monoterpenes derived from their glycosylated form. These compounds contribute to the higher fruit-like characteristic of final product. This chapter reviews metabolic activity of Kloeckera and Hanseniaspora yeasts in several aspects: fermentative capability, aromatic compounds production and transformation of aromatic precursor present in the must, also covers the molecular methods for identifying of the yeast

  2. Life cycle of yeast prions: propagation mediated by amyloid fibrils.

    PubMed

    Inoue, Yuji

    2009-01-01

    Currently, prion phenomena have been detected in various organisms, in addition to mammals affected by transmissible spongiform encephalopathies. In the budding yeast Saccharomyces cerevisiae, various proteins have prion properties and adopt atypical phenotypes as genetic elements, such as the Sup35 and Ure2 proteins, corresponding to the [PSI+] and [URE3] phenotypes, respectively. Each yeast prion protein has a prion-forming region rich in glutamines and/or asparagines, and can form amyloid fibrils in its prion conformation. Studies on yeast prions have revealed that the amyloid fibrils play critical roles in the life cycle of the yeast prion. First, the amyloid fibril binds the normal prion protein and catalyzes a structural conversion into the abnormal form, the key event of the prion phenomenon. Second, the amyloid fibril is related to the strain differences of the prion phenotypes, by its substructural differences. Third, the number of prion elements multiplies by the fragmentation of amyloid fibrils, which is mediated by a chaperone system in which Hsp104 plays a central role, and the prion elements are distributed to the daughter cells during cell division. Moreover, heterologous prion-prion communications may occur, probably by cross-seeding of amyloid fibrils among different prion proteins in the same yeast cell. Findings achieved by yeast prion studies are making great contributions toward understanding the characteristics of amyloid fibrils and prions.

  3. Association between Grape Yeast Communities and the Vineyard Ecosystems

    PubMed Central

    Drumonde-Neves, João; Lima, Teresa; Schuller, Dorit; Pais, Célia

    2017-01-01

    The grape yeast biota from several wine-producing areas, with distinct soil types and grapevine training systems, was assessed on five islands of Azores Archipelago, and differences in yeast communities composition associated with the geographic origin of the grapes were explored. Fifty-seven grape samples belonging to the Vitis vinifera grapevine cultivars Verdelho dos Açores (Verdelho), Arinto da Terceira (Arinto) and Terrantez do Pico (Terrantez) were collected in two consecutive years and 40 spontaneous fermentations were achieved. A total of 1710 yeast isolates were obtained from freshly crushed grapes and 1200 from final stage of fermentations. Twenty-eight species were identified, Hanseniaspura uvarum, Pichia terricola and Metschnikowia pulcherrima being the three most representative species isolated. Candida carpophila was encountered for the first time as an inhabitant of grape or wine-associated environments. In both sampling years, a higher proportion of H. uvarum in fresh grapes from Verdelho cultivar was observed, in comparison with Arinto cultivar. Qualitatively significant differences were found among yeast communities from several locations on five islands of the Archipelago, particularly in locations with distinctive agro-ecological compositions. Our results are in agreement with the statement that grape-associated microbial biogeography is non-randomly associated with interactions of climate, soil, cultivar, and vine training systems in vineyard ecosystems. Our observations strongly support a possible linkage between grape yeast and wine typicality, reinforcing the statement that different viticultural terroirs harbor distinctive yeast biota, in particular in vineyards with very distinctive environmental conditions. PMID:28085916

  4. Yeast diversity on grapes in two German wine growing regions.

    PubMed

    Brysch-Herzberg, Michael; Seidel, Martin

    2015-12-02

    The yeast diversity on wine grapes in Germany, one of the most northern wine growing regions of the world, was investigated by means of a culture dependent approach. All yeast isolates were identified by sequence analysis of the D1/D2 domain of the 26S rDNA and the ITS region. Besides Hanseniaspora uvarum and Metschnikowia pulcherrima, which are well known to be abundant on grapes, Metschnikowia viticola, Rhodosporidium babjevae, and Curvibasidium pallidicorallinum, as well as two potentially new species related to Sporidiobolus pararoseus and Filobasidium floriforme, turned out to be typical members of the grape yeast community. We found M. viticola in about half of the grape samples in high abundance. Our data strongly suggest that M. viticola is one of the most important fermenting yeast species on grapes in the temperate climate of Germany. The frequent occurrence of Cu. pallidicorallinum and strains related to F. floriforme is a new finding. The current investigation provides information on the distribution of recently described yeast species, some of which are known from a very few strains up to now. Interestingly yeasts known for their role in the wine making process, such as Saccharomyces cerevisiae, Saccharomyces bayanus ssp. uvarum, Torulaspora delbrueckii, and Zygosaccharomyces bailii, were not found in the grape samples.

  5. Yeast diversity of sourdoughs and associated metabolic properties and functionalities.

    PubMed

    De Vuyst, Luc; Harth, Henning; Van Kerrebroeck, Simon; Leroy, Frédéric

    2016-12-19

    Together with acidifying lactic acid bacteria, yeasts play a key role in the production process of sourdough, where they are either naturally present or added as a starter culture. Worldwide, a diversity of yeast species is encountered, with Saccharomyces cerevisiae, Candida humilis, Kazachstania exigua, Pichia kudriavzevii, Wickerhamomyces anomalus, and Torulaspora delbrueckii among the most common ones. Sourdough-adapted yeasts are able to withstand the stress conditions encountered during their growth, including nutrient starvation as well as the effects of acidic, oxidative, thermal, and osmotic stresses. From a technological point of view, their metabolism primarily contributes to the leavening and flavour of sourdough products. Besides ethanol and carbon dioxide, yeasts can produce metabolites that specifically affect flavour, such as organic acids, diacetyl, higher alcohols from branched-chain amino acids, and esters derived thereof. Additionally, several yeast strains possess functional properties that can potentially lead to nutritional and safety advantages. These properties encompass the production of vitamins, an improvement of the bioavailability of phenolic compounds, the dephosphorylation of phytic acid, the presence of probiotic potential, and the inhibition of fungi and their mycotoxin production. Strains of diverse species are new candidate functional starter cultures, offering opportunities beyond the conventional use of baker's yeast.

  6. Association between Grape Yeast Communities and the Vineyard Ecosystems.

    PubMed

    Drumonde-Neves, João; Franco-Duarte, Ricardo; Lima, Teresa; Schuller, Dorit; Pais, Célia

    2017-01-01

    The grape yeast biota from several wine-producing areas, with distinct soil types and grapevine training systems, was assessed on five islands of Azores Archipelago, and differences in yeast communities composition associated with the geographic origin of the grapes were explored. Fifty-seven grape samples belonging to the Vitis vinifera grapevine cultivars Verdelho dos Açores (Verdelho), Arinto da Terceira (Arinto) and Terrantez do Pico (Terrantez) were collected in two consecutive years and 40 spontaneous fermentations were achieved. A total of 1710 yeast isolates were obtained from freshly crushed grapes and 1200 from final stage of fermentations. Twenty-eight species were identified, Hanseniaspura uvarum, Pichia terricola and Metschnikowia pulcherrima being the three most representative species isolated. Candida carpophila was encountered for the first time as an inhabitant of grape or wine-associated environments. In both sampling years, a higher proportion of H. uvarum in fresh grapes from Verdelho cultivar was observed, in comparison with Arinto cultivar. Qualitatively significant differences were found among yeast communities from several locations on five islands of the Archipelago, particularly in locations with distinctive agro-ecological compositions. Our results are in agreement with the statement that grape-associated microbial biogeography is non-randomly associated with interactions of climate, soil, cultivar, and vine training systems in vineyard ecosystems. Our observations strongly support a possible linkage between grape yeast and wine typicality, reinforcing the statement that different viticultural terroirs harbor distinctive yeast biota, in particular in vineyards with very distinctive environmental conditions.

  7. Plant farnesyltransferase can restore yeast Ras signaling and mating.

    PubMed Central

    Yalovsky, S; Trueblood, C E; Callan, K L; Narita, J O; Jenkins, S M; Rine, J; Gruissem, W

    1997-01-01

    Farnesyltransferase (FTase) is a heterodimeric enzyme that modifies a group of proteins, including Ras, in mammals and yeasts. Plant FTase alpha and beta subunits were cloned from tomato and expressed in the yeast Saccharomyces cerevisiae to assess their functional conservation in farnesylating Ras and a-factor proteins, which are important for cell growth and mating. The tomato FTase beta subunit (LeFTB) alone was unable to complement the growth defect of ram1 delta mutant yeast strains in which the chromosomal FTase beta subunit gene was deleted, but coexpression of LeFTB with the plant alpha subunit gene (LeFTA) restored normal growth, Ras membrane association, and mating. LeFTB contains a novel 66-amino-acid sequence domain whose deletion reduces the efficiency of tomato FTase to restore normal growth to yeast ram1 delta strains. Coexpression of LeFTA and LeFTB in either yeast or insect cells yielded a functional enzyme that correctly farnesylated CaaX-motif-containing peptides. Despite their low degree of sequence homology, yeast and plant FTases shared similar in vivo and in vitro substrate specificities, demonstrating that this enzymatic modification of proteins with intermediates from the isoprenoid biosynthesis pathway is conserved in evolutionarily divergent eukaryotes. PMID:9121446

  8. In vitro antifungal activity of fluconazole and voriconazole against non-Candida yeasts and yeast-like fungi clinical isolates.

    PubMed

    Mandras, Narcisa; Roana, Janira; Scalas, Daniela; Fucale, Giacomo; Allizond, Valeria; Banche, Giuliana; Barbui, Anna; Li Vigni, Nicolò; Newell, Vance A; Cuffini, Anna Maria; Tullio, Vivian

    2015-10-01

    The risk of opportunistic infections caused by non-Candida yeasts and yeast-like fungi is increasingly common, mainly in immunocompromised patients. Appropriate first-line therapy has not been defined and standardized, mainly due to the low number of cases reported. To improve empirical treatment guidelines, we describe the susceptibility profile to fluconazole and voriconazole of 176 non-Candida yeasts and yeast-like fungi collected from hospitals in Piedmont, North West Italy from January 2009 to December 2013. The results showed that most isolates are susceptible to voriconazole (94%), but less susceptible to fluconazole (78%), suggesting that voriconazole could be used as first-line therapy in infections caused by these fungi.

  9. Vacuole Partitioning during Meiotic Division in Yeast

    PubMed Central

    Roeder, A. D.; Shaw, J. M.

    1996-01-01

    We have examined the partitioning of the yeast vacuole during meiotic division. In pulse-chase experiments, vacuoles labeled with the lumenal ade2 fluorophore or the membrane-specific dye FM 4-64 were not inherited by haploid spores. Instead, these fluorescent markers were excluded from spores and trapped between the spore cell walls and the ascus. Serial optical sections using a confocal microscope confirmed that spores did not inherit detectable amounts of fluorescently labeled vacuoles. Moreover, indirect immunofluorescence studies established that an endogenous vacuolar membrane protein, alkaline phosphatase, and a soluable vacuolar protease, carboxypeptidase Y, were also detected outside spores after meiotic division. Spores that did not inherit ade2- or FM 4-64-labeled vacuoles did generate an organelle that could be visualized by subsequent staining with vacuole-specific fluorophores. These data contrast with genetic evidence that a soluble vacuolar protease is inherited by spores. When the partitioning of both types of markers was examined in sporulating cultures, the vacuolar protease activity was inherited by spores while fluorescently labeled vacuoles were largely excluded from spores. Our results indicate that the majority of the diploid vacuole, both soluble contents and membrane-bound components, are excluded from spores formed during meiotic division. PMID:8889511

  10. Cargo selectivity of yeast sorting nexins.

    PubMed

    Bean, Björn D M; Davey, Michael; Conibear, Elizabeth

    2017-02-01

    Sorting nexins are PX domain-containing proteins that bind phospholipids and often act in membrane trafficking where they help to select cargo. However, the functions and cargo specificities of many sorting nexins are unknown. Here, a high-throughput imaging screen was used to identify new sorting nexin cargo in the yeast Saccharomyces cerevisiae. Deletions of 9 different sorting nexins were screened for mislocalization of a set of green fluorescent protein (GFP)-tagged membrane proteins found at the plasma membrane, Golgi or endosomes. This identified 27 proteins that require 1 or more sorting nexins for their correct localization, 23 of which represent novel sorting nexin cargo. Nine hits whose sorting was dependent on Snx4, the sorting nexin-containing retromer complex, or both retromer and Snx3, were examined in detail to search for potential sorting motifs. We identified cytosolic domains of Ear1, Ymd8 and Ymr010w that conferred retromer-dependent sorting on a chimeric reporter and identified conserved residues required for this sorting in a functional assay. This work defined a consensus sequence for retromer and Snx3-dependent sorting.

  11. Development of yeasts for xylose fermentation

    SciTech Connect

    Jeffries, T.W.; Yang, V.; Marks, J.; Amartey, S.; Kenealy, W.R.; Cho, J.Y.; Dahn, K.; Davis, B.P.

    1993-12-31

    Xylose is an abundant sugar in hardwoods and agricultural residues. Its use is essential for any economical conversion of lignocellulose to ethanol. Only a few yeasts ferment xylose effectively. Our results show that the best strains are Candida shehatae ATCC 2984 and Pichia stipitis CBS 6054. Wild type strains of C. shehatae ATCC 22984 will produce 56 g/L of ethanol from xylose within 48 h in a fed batch fermentation. We have obtained improved mutants of P.stipitis by selecting for growth on L-xylose and L-arabinose. Mutant strains produce up to 55% more ethanol than the parent and exhibit higher specific fermentation rates. We have also developed an effective transformation system that enables the introduction and expression of heterologous DNA on integrating and autonomous vectors. The transformation system for P. stipitis is based on its URA3 gene as a selectable marker and an autonomous replication sequence (ARS) which we isolated from the parent. We are using integrating and ARS vectors to metabolically engineer P. stipitis by altering the regulation and expression of key enzymes. As model systems we are examining the expression of alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC) that are present in limiting amounts or induced only under non-growth conditions.

  12. Mechanical feedback stabilizes budding yeast morphogenesis

    NASA Astrophysics Data System (ADS)

    Banavar, Samhita; Trogdon, Michael; Petzold, Linda; Campas, Otger

    Walled cells have the ability to remodel their shape while sustaining an internal turgor pressure that can reach values up to 10 atmospheres. This requires a tight and simultaneous regulation of cell wall assembly and mechanochemistry, but the underlying mechanisms by which this is achieved remain unclear. Using the growth of mating projections in budding yeast (S. cerevisiae) as a motivating example, we have developed a theoretical description that couples the mechanics of cell wall expansion and assembly via a mechanical feedback. In the absence of a mechanical feedback, cell morphogenesis is inherently unstable. The presence of a mechanical feedback stabilizes changes in cell shape and growth, and provides a mechanism to prevent cell lysis in a wide range of conditions. We solve for the dynamics of the system and obtain the different dynamical regimes. In particular, we show that several parameters affect the stability of growth, including the strength of mechanical feedback in the system. Finally, we compare our results to existing experimental data.

  13. Genetic basis of metabolome variation in yeast.

    PubMed

    Breunig, Jeffrey S; Hackett, Sean R; Rabinowitz, Joshua D; Kruglyak, Leonid

    2014-03-01

    Metabolism, the conversion of nutrients into usable energy and biochemical building blocks, is an essential feature of all cells. The genetic factors responsible for inter-individual metabolic variability remain poorly understood. To investigate genetic causes of metabolome variation, we measured the concentrations of 74 metabolites across ~ 100 segregants from a Saccharomyces cerevisiae cross by liquid chromatography-tandem mass spectrometry. We found 52 quantitative trait loci for 34 metabolites. These included linkages due to overt changes in metabolic genes, e.g., linking pyrimidine intermediates to the deletion of ura3. They also included linkages not directly related to metabolic enzymes, such as those for five central carbon metabolites to ira2, a Ras/PKA pathway regulator, and for the metabolites, S-adenosyl-methionine and S-adenosyl-homocysteine to slt2, a MAP kinase involved in cell wall integrity. The variant of ira2 that elevates metabolite levels also increases glucose uptake and ethanol secretion. These results highlight specific examples of genetic variability, including in genes without prior known metabolic regulatory function, that impact yeast metabolism.

  14. Genetic Basis of Metabolome Variation in Yeast

    PubMed Central

    Breunig, Jeffrey S.; Hackett, Sean R.; Rabinowitz, Joshua D.; Kruglyak, Leonid

    2014-01-01

    Metabolism, the conversion of nutrients into usable energy and biochemical building blocks, is an essential feature of all cells. The genetic factors responsible for inter-individual metabolic variability remain poorly understood. To investigate genetic causes of metabolome variation, we measured the concentrations of 74 metabolites across 100 segregants from a Saccharomyces cerevisiae cross by liquid chromatography-tandem mass spectrometry. We found 52 quantitative trait loci for 34 metabolites. These included linkages due to overt changes in metabolic genes, e.g., linking pyrimidine intermediates to the deletion of ura3. They also included linkages not directly related to metabolic enzymes, such as those for five central carbon metabolites to ira2, a Ras/PKA pathway regulator, and for the metabolites, S-adenosyl-methionine and S-adenosyl-homocysteine to slt2, a MAP kinase involved in cell wall integrity. The variant of ira2 that elevates metabolite levels also increases glucose uptake and ethanol secretion. These results highlight specific examples of genetic variability, including in genes without prior known metabolic regulatory function, that impact yeast metabolism. PMID:24603560

  15. Reversible, cooperative reactions of yeast vacuole docking

    PubMed Central

    Jun, Youngsoo; Thorngren, Naomi; Starai, Vincent J; Fratti, Rutilio A; Collins, Kevin; Wickner, William

    2006-01-01

    Homotypic yeast vacuole fusion occurs in three stages: (i) priming reactions, which are independent of vacuole clustering, (ii) docking, in which vacuoles cluster and accumulate fusion proteins and fusion regulatory lipids at a ring-shaped microdomain surrounding the apposed membranes of each docked vacuole, where fusion will occur, and (iii) bilayer fusion/compartment mixing. These stages require vacuolar SNAREs, SNARE-chaperones, GTPases, effector complexes, and chemically minor but functionally important lipids. For each, we have developed specific ligands that block fusion and conditions that reverse each block. Using them, we test whether docking entails a linearly ordered series of catalytic events, marked by sequential acquisition of resistance to inhibitors, or whether docking subreactions are cooperative and/or reversible. We find that each fusion protein and regulatory lipid is needed throughout docking, indicative of a reversible or highly cooperative assembly of the fusion-competent vertex ring. In accord with this cooperativity, vertices enriched in one fusion catalyst are enriched in others. Docked vacuoles finally assemble SNARE complexes, yet still require physiological temperature and lipid rearrangements to complete fusion. PMID:17082764

  16. Modular assembly of yeast cytochrome oxidase.

    PubMed

    McStay, Gavin P; Su, Chen Hsien; Tzagoloff, Alexander

    2013-02-01

    Previous studies of yeast cytochrome oxidase (COX) biogenesis identified Cox1p, one of the three mitochondrially encoded core subunits, in two high-molecular weight complexes combined with regulatory/assembly factors essential for expression of this subunit. In the present study we use pulse-chase labeling experiments in conjunction with isolated mitochondria to identify new Cox1p intermediates and place them in an ordered pathway. Our results indicate that before its assimilation into COX, Cox1p transitions through five intermediates that are differentiated by their compositions of accessory factors and of two of the eight imported subunits. We propose a model of COX biogenesis in which Cox1p and the two other mitochondrial gene products, Cox2p and Cox3p, constitute independent assembly modules, each with its own complement of subunits. Unlike their bacterial counterparts, which are composed only of the individual core subunits, the final sequence in which the mitochondrial modules associate to form the holoenzyme may have been conserved during evolution.

  17. A unified model for yeast transcript definition.

    PubMed

    de Boer, Carl G; van Bakel, Harm; Tsui, Kyle; Li, Joyce; Morris, Quaid D; Nislow, Corey; Greenblatt, Jack F; Hughes, Timothy R

    2014-01-01

    Identifying genes in the genomic context is central to a cell's ability to interpret the genome. Yet, in general, the signals used to define eukaryotic genes are poorly described. Here, we derived simple classifiers that identify where transcription will initiate and terminate using nucleic acid sequence features detectable by the yeast cell, which we integrate into a Unified Model (UM) that models transcription as a whole. The cis-elements that denote where transcription initiates function primarily through nucleosome depletion, and, using a synthetic promoter system, we show that most of these elements are sufficient to initiate transcription in vivo. Hrp1 binding sites are the major characteristic of terminators; these binding sites are often clustered in terminator regions and can terminate transcription bidirectionally. The UM predicts global transcript structure by modeling transcription of the genome using a hidden Markov model whose emissions are the outputs of the initiation and termination classifiers. We validated the novel predictions of the UM with available RNA-seq data and tested it further by directly comparing the transcript structure predicted by the model to the transcription generated by the cell for synthetic DNA segments of random design. We show that the UM identifies transcription start sites more accurately than the initiation classifier alone, indicating that the relative arrangement of promoter and terminator elements influences their function. Our model presents a concrete description of how the cell defines transcript units, explains the existence of nongenic transcripts, and provides insight into genome evolution.

  18. Electrochemical Regulation of Budding Yeast Polarity

    PubMed Central

    Piel, Matthieu; Chang, Fred; Minc, Nicolas

    2014-01-01

    Cells are naturally surrounded by organized electrical signals in the form of local ion fluxes, membrane potential, and electric fields (EFs) at their surface. Although the contribution of electrochemical elements to cell polarity and migration is beginning to be appreciated, underlying mechanisms are not known. Here we show that an exogenous EF can orient cell polarization in budding yeast (Saccharomyces cerevisiae) cells, directing the growth of mating projections towards sites of hyperpolarized membrane potential, while directing bud emergence in the opposite direction, towards sites of depolarized potential. Using an optogenetic approach, we demonstrate that a local change in membrane potential triggered by light is sufficient to direct cell polarization. Screens for mutants with altered EF responses identify genes involved in transducing electrochemical signals to the polarity machinery. Membrane potential, which is regulated by the potassium transporter Trk1p, is required for polarity orientation during mating and EF response. Membrane potential may regulate membrane charges through negatively charged phosphatidylserines (PSs), which act to position the Cdc42p-based polarity machinery. These studies thus define an electrochemical pathway that directs the orientation of cell polarization. PMID:25548923

  19. High gas pressure effects on yeast.

    PubMed

    Espinasse, V; Perrier-Cornet, J-M; Marecat, A; Gervais, P

    2008-11-01

    Dried microorganisms are particularly resistant to high hydrostatic pressure effects. However, exposure to high pressures of nitrogen proved to be effective in inactivating dried yeasts. In this study, we tried to elucidate this mechanism on Saccharomyces cerevisiae. High-pressure treatments were performed using different inert gases at 150 MPa and 25 degrees C with holding time values up to 12 months. The influence of cell hydration was also investigated. For fully hydrated cells, pressurized gases had little specific effect: cell inactivation was mainly due to compression effects. However, dried cells were sensitive to high pressure of gases. In this latter case, two inactivation kinetics were observed. For holding time up to 1 h, the inactivation rate increased to 4 log and was linked to a loss of membrane integrity and the presence of damage on the cell wall. In such case cell inactivation would be due to gas sorption and desorption phenomena which would rupture dried cells during a fast pressure release. Gas sorption would occur in cell lipid phases. For longer holding times, the inactivation rate increased more slightly due to compression effects and/or to a slower gas sorption. Water therefore played a key role in cell sensitivity to fast gas pressure release. Two hypotheses were proposed to explain this phenomenon: the rigidity of vitrified dried cells and the presence of glassy solid phases which would favor intracellular gas expansion. Our results showed that dried microorganisms can be ruptured and inactivated by a fast pressure release with gases.

  20. Yeast mutants overproducing iso-cytochromes c

    SciTech Connect

    Sherman, F.; Cardillo, T.S.; Errede, B.; Friedman, L.; McKnight, G.; Stiles, J.I.

    1980-01-01

    For over 15 years, the iso-cytochrome c system in the yeast Saccharomyces cerevisiae has been used to investigate a multitude of problems in genetics and molecular biology. More recently, attention has been focused on using mutants for examining translation and transcriptional processes and for probing regulatory regions governing gene expression. In an effort to explore regulatory mechanisms and to investigate mutational alterations that lead to increased levels of gene products, we have isolated and characterized mutants that overproduce cytochrome c. In this paper we have briefly summarized background information of some essential features of the iso-cytochrome c system and we have described the types of mutants that overproduce iso-1-cytochrome c or iso-2-cytochrome c. Genetic procedures and recombinant DNA procedures were used to demonstrate that abnormally high amounts of gene products occur in mutants as result of duplications of gene copies or of extended alteration of regulatory regions. The results summarized in this paper point out the requirements of gross mutational changes or rearrangements of chromosomal segments for augmenting gene products.

  1. Yeast peroxisomes: structure, functions and biotechnological opportunities.

    PubMed

    Sibirny, Andriy A

    2016-06-01

    Peroxisomes are ubiquitous organelles found in most eukaryotic cells. In yeasts, peroxisomes play important roles in cell metabolism, especially in different catabolic processes including fatty acid β-oxidation, the glyoxylic shunt and methanol metabolism, as well as some biosynthetic processes. In addition, peroxisomes are the compartment in which oxidases and catalase are localized. New peroxisomes mainly arise by fission of pre-existing ones, although they can also be formed from the endoplasmic reticulum (ER). Peroxisomes consist of matrix-soluble proteins and membrane proteins known as peroxins. A total of 34 PEX peroxin genes and proteins have been identified to date. and their functions have been elucidated. Protein import into peroxisomes depends on peroxins and requires specific signals in the structure of transported proteins: PTS1, PTS2 and mPTS. The mechanisms of metabolite penetration into peroxisomes are still poorly understood. Peroxisome number and the volume occupied by these organelles are tightly regulated. Methanol, fatty acids and methylamine act as efficient peroxisome proliferators, whereas glucose and ethanol induce peroxisome autophagic degradation (pexophagy). To date, 42 Atg proteins involved in pexophagy are known. Catabolism and alcoholic fermentation of the major pentose sugar, xylose, depend on peroxisomal enzymes. Overexpression of peroxisomal transketolase and transaldolase activates xylose fermentation. Peroxisomes could be useful as target organelles for overexpression of foreign toxic proteins.

  2. Pulsatile Dynamics in the Yeast Proteome

    PubMed Central

    Dalal, Chiraj K.; Cai, Long; Lin, Yihan; Rahbar, Kasra; Elowitz, Michael B.

    2014-01-01

    The activation of transcription factors in response to environmental conditions is fundamental to cellular regulation. Recent work has revealed that some transcription factors are activated in stochastic pulses of nuclear localization, rather than at a constant level, even in a constant environment. In such cases, signals control the mean activity of the transcription factor by modulating the frequency, duration, or amplitude of these pulses. Although specific pulsatile transcription factors have been identified in diverse cell types, it has remained unclear how prevalent pulsing is within the cell, how variable pulsing behaviors are between genes, and whether pulsing is specific to transcriptional regulators or employed more broadly. To address these issues, we performed a proteome-wide movie-based screen to systematically identify localization-based pulsing behaviors in Saccharomyces cerevisiae. The screen examined all genes in a previously developed fluorescent protein fusion library of 4159 strains in multiple media conditions. This approach revealed stochastic pulsing in 10 proteins, all transcription factors. In each case, pulse dynamics were heterogeneous and unsynchronized among cells in clonal populations. Pulsing is the only dynamic localization behavior we observed, and it tends to occur in pairs of paralagous and redundant proteins. Taken together, these results suggest that pulsatile dynamics play a pervasive role in yeast and may be similarly prevalent in other eukaryotic species. PMID:25220054

  3. Molecular architecture of the yeast Mediator complex

    PubMed Central

    Robinson, Philip J; Trnka, Michael J; Pellarin, Riccardo; Greenberg, Charles H; Bushnell, David A; Davis, Ralph; Burlingame, Alma L; Sali, Andrej; Kornberg, Roger D

    2015-01-01

    The 21-subunit Mediator complex transduces regulatory information from enhancers to promoters, and performs an essential role in the initiation of transcription in all eukaryotes. Structural information on two-thirds of the complex has been limited to coarse subunit mapping onto 2-D images from electron micrographs. We have performed chemical cross-linking and mass spectrometry, and combined the results with information from X-ray crystallography, homology modeling, and cryo-electron microscopy by an integrative modeling approach to determine a 3-D model of the entire Mediator complex. The approach is validated by the use of X-ray crystal structures as internal controls and by consistency with previous results from electron microscopy and yeast two-hybrid screens. The model shows the locations and orientations of all Mediator subunits, as well as subunit interfaces and some secondary structural elements. Segments of 20–40 amino acid residues are placed with an average precision of 20 Å. The model reveals roles of individual subunits in the organization of the complex. DOI: http://dx.doi.org/10.7554/eLife.08719.001 PMID:26402457

  4. Computational Modeling of Lipid Metabolism in Yeast

    PubMed Central

    Schützhold, Vera; Hahn, Jens; Tummler, Katja; Klipp, Edda

    2016-01-01

    Lipid metabolism is essential for all major cell functions and has recently gained increasing attention in research and health studies. However, mathematical modeling by means of classical approaches such as stoichiometric networks and ordinary differential equation systems has not yet provided satisfactory insights, due to the complexity of lipid metabolism characterized by many different species with only slight differences and by promiscuous multifunctional enzymes. Here, we present an object-oriented stochastic model approach as a way to cope with the complex lipid metabolic network. While all lipid species are treated objects in the model, they can be modified by the respective converting reactions based on reaction rules, a hybrid method that integrates benefits of agent-based and classical stochastic simulation. This approach allows to follow the dynamics of all lipid species with different fatty acids, different degrees of saturation and different headgroups over time and to analyze the effect of parameter changes, potential mutations in the catalyzing enzymes or provision of different precursors. Applied to yeast metabolism during one cell cycle period, we could analyze the distribution of all lipids to the various membranes in time-dependent manner. The presented approach allows to efficiently treat the complexity of cellular lipid metabolism and to derive conclusions on the time- and location-dependent distributions of lipid species and their properties such as saturation. It is widely applicable, easily extendable and will provide further insights in healthy and diseased states of cell metabolism. PMID:27730126

  5. Yeast cells can access distinct quiescent states.

    PubMed

    Klosinska, Maja M; Crutchfield, Christopher A; Bradley, Patrick H; Rabinowitz, Joshua D; Broach, James R

    2011-02-15

    We conducted a phenotypic, transcriptional, metabolic, and genetic analysis of quiescence in yeast induced by starvation of prototrophic cells for one of three essential nutrients (glucose, nitrogen, or phosphate) and compared those results with those obtained with cells growing slowly due to nutrient limitation. These studies address two related questions: (1) Is quiescence a state distinct from any attained during mitotic growth, and (2) does the nature of quiescence differ depending on the means by which it is induced? We found that either limitation or starvation for any of the three nutrients elicits all of the physiological properties associated with quiescence, such as enhanced cell wall integrity and resistance to heat shock and oxidative stress. Moreover, the starvations result in a common transcriptional program, which is in large part a direct extrapolation of the changes that occur during slow growth. In contrast, the metabolic changes that occur upon starvation and the genetic requirements for surviving starvation differ significantly depending on the nutrient for which the cell is starved. The genes needed by cells to survive starvation do not overlap the genes that are induced upon starvation. We conclude that cells do not access a unique and discrete G(0) state, but rather are programmed, when nutrients are scarce, to prepare for a range of possible future stressors. Moreover, these survival strategies are not unique to quiescence, but are engaged by the cell in proportion to nutrient scarcity.

  6. A unified model for yeast transcript definition

    PubMed Central

    de Boer, Carl G.; van Bakel, Harm; Tsui, Kyle; Li, Joyce; Morris, Quaid D.; Nislow, Corey; Greenblatt, Jack F.; Hughes, Timothy R.

    2014-01-01

    Identifying genes in the genomic context is central to a cell's ability to interpret the genome. Yet, in general, the signals used to define eukaryotic genes are poorly described. Here, we derived simple classifiers that identify where transcription will initiate and terminate using nucleic acid sequence features detectable by the yeast cell, which we integrate into a Unified Model (UM) that models transcription as a whole. The cis-elements that denote where transcription initiates function primarily through nucleosome depletion, and, using a synthetic promoter system, we show that most of these elements are sufficient to initiate transcription in vivo. Hrp1 binding sites are the major characteristic of terminators; these binding sites are often clustered in terminator regions and can terminate transcription bidirectionally. The UM predicts global transcript structure by modeling transcription of the genome using a hidden Markov model whose emissions are the outputs of the initiation and termination classifiers. We validated the novel predictions of the UM with available RNA-seq data and tested it further by directly comparing the transcript structure predicted by the model to the transcription generated by the cell for synthetic DNA segments of random design. We show that the UM identifies transcription start sites more accurately than the initiation classifier alone, indicating that the relative arrangement of promoter and terminator elements influences their function. Our model presents a concrete description of how the cell defines transcript units, explains the existence of nongenic transcripts, and provides insight into genome evolution. PMID:24170600

  7. X-ray irradiation of yeast cells

    NASA Astrophysics Data System (ADS)

    Masini, Alessandra; Batani, Dimitri; Previdi, Fabio; Conti, Aldo; Pisani, Francesca; Botto, Cesare; Bortolotto, Fulvia; Torsiello, Flavia; Turcu, I. C. Edmond; Allott, Ric M.; Lisi, Nicola; Milani, Marziale; Costato, Michele; Pozzi, Achille; Koenig, Michel

    1997-10-01

    Saccharomyces Cerevisiae yeast cells were irradiated using the soft X-ray laser-plasma source at Rutherford Laboratory. The aim was to produce a selective damage of enzyme metabolic activity at the wall and membrane level (responsible for fermentation) without interfering with respiration (taking place in mitochondria) and with nuclear and DNA activity. The source was calibrated by PIN diodes and X-ray spectrometers. Teflon stripes were chosen as targets for the UV laser, emitting X-rays at about 0.9 keV, characterized by a very large decay exponent in biological matter. X-ray doses to the different cell compartments were calculated following a Lambert-Bouguet-Beer law. After irradiation, the selective damage to metabolic activity at the membrane level was measured by monitoring CO2 production with pressure silicon detectors. Preliminary results gave evidence of pressure reduction for irradiated samples and non-linear response to doses. Also metabolic oscillations were evidenced in cell suspensions and it was shown that X-ray irradiation changed the oscillation frequency.

  8. Computational Modeling of Lipid Metabolism in Yeast.

    PubMed

    Schützhold, Vera; Hahn, Jens; Tummler, Katja; Klipp, Edda

    2016-01-01

    Lipid metabolism is essential for all major cell functions and has recently gained increasing attention in research and health studies. However, mathematical modeling by means of classical approaches such as stoichiometric networks and ordinary differential equation systems has not yet provided satisfactory insights, due to the complexity of lipid metabolism characterized by many different species with only slight differences and by promiscuous multifunctional enzymes. Here, we present an object-oriented stochastic model approach as a way to cope with the complex lipid metabolic network. While all lipid species are treated objects in the model, they can be modified by the respective converting reactions based on reaction rules, a hybrid method that integrates benefits of agent-based and classical stochastic simulation. This approach allows to follow the dynamics of all lipid species with different fatty acids, different degrees of saturation and different headgroups over time and to analyze the effect of parameter changes, potential mutations in the catalyzing enzymes or provision of different precursors. Applied to yeast metabolism during one cell cycle period, we could analyze the distribution of all lipids to the various membranes in time-dependent manner. The presented approach allows to efficiently treat the complexity of cellular lipid metabolism and to derive conclusions on the time- and location-dependent distributions of lipid species and their properties such as saturation. It is widely applicable, easily extendable and will provide further insights in healthy and diseased states of cell metabolism.

  9. Influence of the farming system on the epiphytic yeasts and yeast-like fungi colonizing grape berries during the ripening process.

    PubMed

    Martins, Guilherme; Vallance, Jessica; Mercier, Anne; Albertin, Warren; Stamatopoulos, Panagiotis; Rey, Patrice; Lonvaud, Aline; Masneuf-Pomarède, Isabelle

    2014-05-02

    Grape berries are colonized by a wide array of epiphytic microorganisms such as yeast and filamentous fungi. This microbiota plays a major role in crop health and also interferes with the winemaking process. In this study, culture-dependent and -independent methods were used to investigate the dynamics and diversity of the yeast and yeast-like microorganisms on the grape berry surface during maturation and the influence of cropping systems in this microflora. The results showed a significant impact of both the farming system and the maturity stage on the epiphytic yeast and yeast-like community. A quantitative approach based on counting cultivable populations indicated an increase in the yeast and yeast-like population during the grape ripening process, reaching a maximum when the berries became overripe. The cultivable yeast and yeast-like population also varied significantly depending on the farming system. Microorganism counts were significantly higher for organically- than conventionally-farmed grapes. The yeast and yeast-like community structures were analysed by culture independent methods, using CE-SSCP. The results revealed changes in the genetic structure of the yeast and yeast-like community throughout the ripening process, as well as the impact of the farming system. Copper-based fungicide treatments were revealed as the main factor responsible for the differences in microbial population densities between samples of different farming systems. The results showed a negative correlation between copper levels and yeast and yeast-like populations, providing evidence that copper inhibited this epiphytic community. Taken together, our results showed that shifts in the microbial community were related to changes in the composition of the grape-berry surface, particularly sugar exudation and the occurrence of copper residues from pesticide treatments.

  10. Solving ethanol production problems with genetically modified yeast strains

    PubMed Central

    Abreu-Cavalheiro, A.; Monteiro, G.

    2013-01-01

    The current world demand for bioethanol is increasing as a consequence of low fossil fuel availability and a growing number of ethanol/gasoline flex-fuel cars. In addition, countries in several parts of the world have agreed to reduce carbon dioxide emissions, and the use of ethanol as a fuel (which produces fewer pollutants than petroleum products) has been considered to be a good alternative to petroleum products. The ethanol that is produced in Brazil from the first-generation process is optimized and can be accomplished at low cost. However, because of the large volume of ethanol that is produced and traded each year, any small improvement in the process could represent a savings of billions dollars. Several Brazilian research programs are investing in sugarcane improvement, but little attention has been given to the improvement of yeast strains that participate in the first-generation process at present. The Brazilian ethanol production process uses sugarcane as a carbon source for the yeast Saccharomyces cerevisiae. Yeast is then grown at a high cellular density and high temperatures in large-capacity open tanks with cells recycle. All of these culture conditions compel the yeast to cope with several types of stress. Among the main stressors are high temperatures and high ethanol concentrations inside the fermentation tanks during alcohol production. Moreover, the competition between the desired yeast strains, which are inoculated at the beginning of the process, with contaminants such as wild type yeasts and bacteria, requires acid treatment to successfully recycle the cells. This review is focused on describing the problems and stressors within the Brazilian ethanol production system. It also highlights some genetic modifications that can help to circumvent these difficulties in yeast. PMID:24516432

  11. Solving ethanol production problems with genetically modified yeast strains.

    PubMed

    Abreu-Cavalheiro, A; Monteiro, G

    2013-01-01

    The current world demand for bioethanol is increasing as a consequence of low fossil fuel availability and a growing number of ethanol/gasoline flex-fuel cars. In addition, countries in several parts of the world have agreed to reduce carbon dioxide emissions, and the use of ethanol as a fuel (which produces fewer pollutants than petroleum products) has been considered to be a good alternative to petroleum products. The ethanol that is produced in Brazil from the first-generation process is optimized and can be accomplished at low cost. However, because of the large volume of ethanol that is produced and traded each year, any small improvement in the process could represent a savings of billions dollars. Several Brazilian research programs are investing in sugarcane improvement, but little attention has been given to the improvement of yeast strains that participate in the first-generation process at present. The Brazilian ethanol production process uses sugarcane as a carbon source for the yeast Saccharomyces cerevisiae. Yeast is then grown at a high cellular density and high temperatures in large-capacity open tanks with cells recycle. All of these culture conditions compel the yeast to cope with several types of stress. Among the main stressors are high temperatures and high ethanol concentrations inside the fermentation tanks during alcohol production. Moreover, the competition between the desired yeast strains, which are inoculated at the beginning of the process, with contaminants such as wild type yeasts and bacteria, requires acid treatment to successfully recycle the cells. This review is focused on describing the problems and stressors within the Brazilian ethanol production system. It also highlights some genetic modifications that can help to circumvent these difficulties in yeast.

  12. Functional domains of yeast hexokinase 2

    PubMed Central

    Peláez, Rafael; Herrero, Pilar; Moreno, Fernando

    2010-01-01

    Hkx2 (hexokinase 2) from Saccharomyces cerevisiae was one of the first metabolic enzymes described as a multifunctional protein. Hxk2 has a double subcellular localization: it functions as a glycolytic enzyme in the cytoplasm and as a regulator of gene transcription of several Mig1-regulated genes in the nucleus. To get more insights into the structure–function relationships of the Hxk2 protein, we followed two different approaches. In the first, we deleted the last eight amino acids of Hxk2 and replaced Ser304 with phenylalanine to generate Hxk2wca. Analysis of this mutant demonstrated that these domains play an essential role in the catalytic activity of yeast Hxk2, but has no effect on the regulatory function of this protein. In the second, we analysed whether amino acids from Lys6 to Met15 of Hxk2 (Hxk2wrf) are essential for the regulatory role of Hxk2 and whether there is an effect on the hexose kinase activity of this protein. In the present paper, we report that the Hxk2wca mutant protein interacts with the Mig1 transcriptional repressor and the Snf1 protein kinase in the nucleus at the level of the SUC2–Mig1 repressor complex. We have demonstrated that Hxk2wca maintained full regulatory function because the glucose-repression signalling of the wild-type machinery is maintained. We also report that the Hxk2wrf mutant allele is incapable of glucose repression signalling because it does not interact with Mig1 at the level of the SUC2–Mig1 repressor complex. The two mutants, Hxk2wca and Hxk2wrf retain single functions, as a transcriptional factor or as an enzyme with hexose-phosphorylating activity, but have lost the original bifunctionality of Hxk2. PMID:20815814

  13. Assembly of the Yeast Cell Wall

    PubMed Central

    Cabib, Enrico; Farkas, Vladimir; Kosík, Ondrej; Blanco, Noelia; Arroyo, Javier; McPhie, Peter

    2008-01-01

    The cross-linking of polysaccharides to assemble new cell wall in fungi requires mechanisms by which a preexisting linkage is broken for each new one made, to allow for the absence of free energy sources outside the plasma membrane. Previous work showed that Crh1p and Crh2p, putative transglycosylases, are required for the linkage of chitin to β(1–3)glucose branches of β(1–6)glucan in the cell wall of budding yeast. To explore the linking reaction in vivo and in vitro, we used fluorescent sulforhodamine-linked laminari-oligosaccharides as artificial chitin acceptors. In vivo, fluorescence was detected in bud scars and at a lower level in the cell contour, both being dependent on the CRH genes. The linking reaction was also shown in digitonin-permeabilized cells, with UDP-N-acetylglucosamine as the substrate for nascent chitin production. Both the nucleotide and the Crh proteins were required here. A gas1 mutant that overexpresses Crh1p showed very high fluorescence both in intact and permeabilized cells. In the latter, fluorescence was still incorporated in patches in the absence of UDP-GlcNAc. Isolated cell walls of this strain, when incubated with sulforhodamine-oligosaccharide, also showed Crhp-dependent fluorescence in patches, which were identified as bud scars. In all three systems, binding of the fluorescent material to chitin was verified by chitinase digestion. Moreover, the cell wall reaction was inhibited by chitooligosaccharides. These results demonstrate that the Crh proteins act by transferring chitin chains to β(1–6)glucan, with a newly observed high activity in the bud scar. The importance of transglycosylation for cell wall assembly is thus firmly established. PMID:18694928

  14. Dynamic Positioning of Mitotic Spindles in Yeast:

    PubMed Central

    Yeh, Elaine; Yang, Charlie; Chin, Elaine; Maddox, Paul; Salmon, E. D.; Lew, Daniel J.; Bloom, Kerry

    2000-01-01

    In the budding yeast Saccharomyces cerevisiae, movement of the mitotic spindle to a predetermined cleavage plane at the bud neck is essential for partitioning chromosomes into the mother and daughter cells. Astral microtubule dynamics are critical to the mechanism that ensures nuclear migration to the bud neck. The nucleus moves in the opposite direction of astral microtubule growth in the mother cell, apparently being “pushed” by microtubule contacts at the cortex. In contrast, microtubules growing toward the neck and within the bud promote nuclear movement in the same direction of microtubule growth, thus “pulling” the nucleus toward the bud neck. Failure of “pulling” is evident in cells lacking Bud6p, Bni1p, Kar9p, or the kinesin homolog, Kip3p. As a consequence, there is a loss of asymmetry in spindle pole body segregation into the bud. The cytoplasmic motor protein, dynein, is not required for nuclear movement to the neck; rather, it has been postulated to contribute to spindle elongation through the neck. In the absence of KAR9, dynein-dependent spindle oscillations are evident before anaphase onset, as are postanaphase dynein-dependent pulling forces that exceed the velocity of wild-type spindle elongation threefold. In addition, dynein-mediated forces on astral microtubules are sufficient to segregate a 2N chromosome set through the neck in the absence of spindle elongation, but cytoplasmic kinesins are not. These observations support a model in which spindle polarity determinants (BUD6, BNI1, KAR9) and cytoplasmic kinesin (KIP3) provide directional cues for spindle orientation to the bud while restraining the spindle to the neck. Cytoplasmic dynein is attenuated by these spindle polarity determinants and kinesin until anaphase onset, when dynein directs spindle elongation to distal points in the mother and bud. PMID:11071919

  15. Characterizing yeast promoters used in Kluyveromyces marxianus.

    PubMed

    Yang, Chun; Hu, Shenglin; Zhu, Songli; Wang, Dongmei; Gao, Xiaolian; Hong, Jiong

    2015-10-01

    Fermentation at higher temperatures can potentially reduce the cooling cost in large-scale fermentation and reduce the contamination risk. Thus, the thermotolerant yeast, Kluyveromyces marxianus, which can grow and ferment at elevated temperatures, is a promising biotechnological tool for future applications. However, the promoters used in K. marxianus are not well characterized, especially at elevated temperatures, which is important in efficient metabolic pathway construction. In this study, six constitutive promoters (P(TDH3), P(PGK), and P(ADH1) from both Saccharomyces cerevisiae and K. marxianus) were evaluated in K. marxianus through the heterologous expression of the KlLAC4, GUSA, and SH BLE genes at various temperatures, with various carbon sources and oxygen conditions. The expression was evaluated at the transcription and protein level using real-time PCR and protein activity determination to eliminate the effect of heterologous protein stability. While the transcription of all the promoters decreased at higher temperatures, the order of their promoting strength at various temperatures with glucose as the carbon source was P(KmPGK) > P(KmTDH3) > P(ScPGK) > P(ScTDH3) > P(KmADH1) > P(ScADH1). When glycerol or xylose was supplied as the carbon source at 42 °C, the order of promoter strength was P(KmPGK) > P(ScPGK) > P(KmADH1) > P(ScADH1) > P(ScTDH3) > P(KmTDH3). The promoter activity of P TDH3 decreased significantly, while the promoter activity of both of the P(ADH1) promoters increased. Oxygen conditions had non-significant effect. The results of this study provide important information for fine-tuned pathway construction for the metabolic engineering of K. marxianus.

  16. Yeast Alcohol Dehydrogenase Structure and Catalysis

    PubMed Central

    2015-01-01

    Yeast (Saccharomyces cerevisiae) alcohol dehydrogenase I (ADH1) is the constitutive enzyme that reduces acetaldehyde to ethanol during the fermentation of glucose. ADH1 is a homotetramer of subunits with 347 amino acid residues. A structure for ADH1 was determined by X-ray crystallography at 2.4 Å resolution. The asymmetric unit contains four different subunits, arranged as similar dimers named AB and CD. The unit cell contains two different tetramers made up of “back-to-back” dimers, AB:AB and CD:CD. The A and C subunits in each dimer are structurally similar, with a closed conformation, bound coenzyme, and the oxygen of 2,2,2-trifluoroethanol ligated to the catalytic zinc in the classical tetrahedral coordination with Cys-43, Cys-153, and His-66. In contrast, the B and D subunits have an open conformation with no bound coenzyme, and the catalytic zinc has an alternative, inverted coordination with Cys-43, Cys-153, His-66, and the carboxylate of Glu-67. The asymmetry in the dimeric subunits of the tetramer provides two structures that appear to be relevant for the catalytic mechanism. The alternative coordination of the zinc may represent an intermediate in the mechanism of displacement of the zinc-bound water with alcohol or aldehyde substrates. Substitution of Glu-67 with Gln-67 decreases the catalytic efficiency by 100-fold. Previous studies of structural modeling, evolutionary relationships, substrate specificity, chemical modification, and site-directed mutagenesis are interpreted more fully with the three-dimensional structure. PMID:25157460

  17. Functional domains of yeast hexokinase 2.

    PubMed

    Peláez, Rafael; Herrero, Pilar; Moreno, Fernando

    2010-11-15

    Hkx2 (hexokinase 2) from Saccharomyces cerevisiae was one of the first metabolic enzymes described as a multifunctional protein. Hxk2 has a double subcellular localization: it functions as a glycolytic enzyme in the cytoplasm and as a regulator of gene transcription of several Mig1-regulated genes in the nucleus. To get more insights into the structure-function relationships of the Hxk2 protein, we followed two different approaches. In the first, we deleted the last eight amino acids of Hxk2 and replaced Ser³⁰⁴ with phenylalanine to generate Hxk2(wca). Analysis of this mutant demonstrated that these domains play an essential role in the catalytic activity of yeast Hxk2, but has no effect on the regulatory function of this protein. In the second, we analysed whether amino acids from Lys⁶ to Met¹⁵ of Hxk2 (Hxk2(wrf)) are essential for the regulatory role of Hxk2 and whether there is an effect on the hexose kinase activity of this protein. In the present paper, we report that the Hxk2(wca) mutant protein interacts with the Mig1 transcriptional repressor and the Snf1 protein kinase in the nucleus at the level of the SUC2-Mig1 repressor complex. We have demonstrated that Hxk2(wca) maintained full regulatory function because the glucose-repression signalling of the wild-type machinery is maintained. We also report that the Hxk2(wrf) mutant allele is incapable of glucose repression signalling because it does not interact with Mig1 at the level of the SUC2-Mig1 repressor complex. The two mutants, Hxk2(wca) and Hxk2(wrf) retain single functions, as a transcriptional factor or as an enzyme with hexose-phosphorylating activity, but have lost the original bifunctionality of Hxk2.

  18. Posttranscriptional Control of Gene Expression in Yeast

    PubMed Central

    McCarthy, John E. G.

    1998-01-01

    Studies of the budding yeast Saccharomyces cerevisiae have greatly advanced our understanding of the posttranscriptional steps of eukaryotic gene expression. Given the wide range of experimental tools applicable to S. cerevisiae and the recent determination of its complete genomic sequence, many of the key challenges of the posttranscriptional control field can be tackled particularly effectively by using this organism. This article reviews the current knowledge of the cellular components and mechanisms related to translation and mRNA decay, with the emphasis on the molecular basis for rate control and gene regulation. Recent progress in characterizing translation factors and their protein-protein and RNA-protein interactions has been rapid. Against the background of a growing body of structural information, the review discusses the thermodynamic and kinetic principles that govern the translation process. As in prokaryotic systems, translational initiation is a key point of control. Modulation of the activities of translational initiation factors imposes global regulation in the cell, while structural features of particular 5′ untranslated regions, such as upstream open reading frames and effector binding sites, allow for gene-specific regulation. Recent data have revealed many new details of the molecular mechanisms involved while providing insight into the functional overlaps and molecular networking that are apparently a key feature of evolving cellular systems. An overall picture of the mechanisms governing mRNA decay has only very recently begun to develop. The latest work has revealed new information about the mRNA decay pathways, the components of the mRNA degradation machinery, and the way in which these might relate to the translation apparatus. Overall, major challenges still to be addressed include the task of relating principles of posttranscriptional control to cellular compartmentalization and polysome structure and the role of molecular channelling

  19. Lipase production by yeasts from extra virgin olive oil.

    PubMed

    Ciafardini, G; Zullo, B A; Iride, A

    2006-02-01

    Newly produced olive oil has an opalescent appearance due to the presence of solid particles and micro-drops of vegetation water from the fruits. Some of our recent microbiological research has shown that a rich micro-flora is present in the suspended fraction of the freshly produced olive oil capable of improving the quality of the oil through the hydrolysis of the oleuropein. Present research however has, for the first time, demonstrated the presence of lipase-positive yeasts in some samples of extra virgin olive oil which can lower the quality of the oil through the hydrolysis of the triglycerides. The tests performed with yeasts of our collection, previously isolated from olive oil, demonstrated that two lipase-producing yeast strains named Saccharomyces cerevisiae 1525 and Williopsis californica 1639 were able to hydrolyse different specific synthetic substrates represented by p-nitrophenyl stearate, 4-nitrophenyl palmitate, tripalmitin and triolein as well as olive oil triglycerides. The lipase activity in S. cerevisiae 1525 was confined to the whole cells, whereas in W. californica 1639 it was also detected in the extracellular fraction. The enzyme activity in both yeasts was influenced by the ratio of the aqueous to the organic phase reaching its maximum value in S. cerevisiae 1525 when the water added to the olive oil was present in a ratio of 0.25% (v/v), whereas in W. californica 1639 the optimal ratio was 1% (v/v). Furthermore, the free fatty acids of olive oil proved to be good inducers of lipase activity in both yeasts. The microbiological analysis carried out on commercial extra virgin olive oil, produced in four different geographic areas, demonstrated that the presence of lipase-producing yeast varied from zero to 56% of the total yeasts detected, according to the source of oil samples. The discovery of lipase-positive yeasts in some extra virgin olive oils leads us to believe that yeasts are able to contribute in a positive or negative way towards

  20. Occurrence of hydrogen sulfide in wine and in fermentation: influence of yeast strain and supplementation of yeast available nitrogen.

    PubMed

    Ugliano, Maurizio; Kolouchova, Radka; Henschke, Paul A

    2011-03-01

    Hydrogen sulfide (H₂S) is a powerful aroma compound largely produced by yeast during fermentation. Its occurrence in wines and other fermented beverages has been associated with off-odors described as rotten egg and/or sewage. While the formation of hydrogen sulfide (H₂S) during fermentation has been extensively studied, it is the final H₂S content of wine that is actually linked to potential off-odors. Nevertheless, factors determining final H₂S content of wine have received little attention, and it is commonly assumed that high H₂S-forming fermentations will result in high final concentrations of H₂S. However, a clear relationship has never been established. In this report, we investigated the contribution of yeast strain and nitrogen addition to H₂S formation during fermentation and its consequent occurrence the resulting wines. Five commercial Saccharomyces cerevisiae wine yeast strains were used to ferment a Chardonnay juice containing 110 mg/l of YAN (yeast assimilable nitrogen), supplemented with di-ammonium phosphate (DAP) to increase YAN concentration to moderate (260 mg/l) and high (410 mg/l) levels. In contrast to the widely reported decrease in H₂S production in response to DAP addition, a non-linear relationship was found such that moderate DAP supplementation resulted in a remarkable increase in H₂S formation by each of the five wine yeasts. H₂S content of the finished wine was affected by yeast strain, YAN, and fermentation vigor. However, we did not observe a correlation between concentration of H₂S in the finished wines and H₂S produced during fermentation, with low-forming fermentations often having relatively high final H₂S and vice versa. Management of H₂S in wine through nitrogen supplementation requires knowledge of initial YAN and yeast H₂S characteristics.

  1. Table wine from tropical fruits utilizing natural yeast isolates.

    PubMed

    Baidya, Dipak; Chakraborty, Ivi; Saha, Jayanta

    2016-03-01

    An attempt was made to utilize few widely available tropical fruits to develop wine with the objective of comparing the fermentation efficiency (along with progress in fermentation) of two efficient yeast isolates with commercially available strain. Fruit wine from juices of fully ripe mango, jackfruit and pineapple alone and in blended combinations of all three fruit juice (2: 1: 2) was prepared using two different yeasts (Y4 and Y7) isolated from natural plain date palm juice and one standard Saccharomyces cerevisiae (MTCC-170) collected from IMTECH, Chandigar. Juices were extracted by using pectinase enzyme at 0.15-0.20 % of pulp. Changes in °Brix, titratable acid content, pH, total viable yeast count were recorded and rate of fermentation, sugar use efficiency were determined at every 24-hour interval up to the completion (6 days after inoculation) of fermentation. Considering all the quality parameter as well as fermentation efficiency, yeast isolate Y7 was found superior followed by Y4 as fermenting agent and pineapple juice as sole substrate found to be the most suitable medium for production of wine followed by fruit juice blending. In interpreting the efficacy of fruit and yeast in combination, pineapple juice inoculated with Y7 found to be the best in reducing the degree Brix to its lowest from initial 24 degree.

  2. Analysis of the Secretomes of Paracoccidioides Mycelia and Yeast Cells

    PubMed Central

    Weber, Simone Schneider; Parente, Ana Flávia Alves; Borges, Clayton Luiz; Parente, Juliana Alves; Bailão, Alexandre Melo; de Almeida Soares, Célia Maria

    2012-01-01

    Paracoccidioides, a complex of several phylogenetic species, is the causative agent of paracoccidioidomycosis. The ability of pathogenic fungi to develop a multifaceted response to the wide variety of stressors found in the host environment is important for virulence and pathogenesis. Extracellular proteins represent key mediators of the host-parasite interaction. To analyze the expression profile of the proteins secreted by Paracoccidioides, Pb01 mycelia and yeast cells, we used a proteomics approach combining two-dimensional electrophoresis with matrix-assisted laser desorption ionization quadrupole time-of-flight mass spectrometry (MALDI-Q-TOF MS/MS). From three biological replicates, 356 and 388 spots were detected, in mycelium and yeast cell secretomes, respectively. In this study, 160 non-redundant proteins/isoforms were indentified, including 30 and 24 proteins preferentially secreted in mycelia and yeast cells, respectively. In silico analyses revealed that 65% of the identified proteins/isoforms were secreted primarily via non-conventional pathways. We also investigated the influence of protein export inhibition in the phagocytosis of Paracoccidioides by macrophages. The addition of Brefeldin A to the culture medium significantly decreased the production of secreted proteins by both Paracoccidioides and internalized yeast cells by macrophages. In contrast, the addition of concentrated culture supernatant to the co-cultivation significantly increased the number of internalized yeast cells by macrophages. Importantly, the proteins detected in the fungal secretome were also identified within macrophages. These results indicate that Paracoccidioides extracellular proteins are important for the fungal interaction with the host. PMID:23272246

  3. Grape berry yeast communities: influence of fungicide treatments.

    PubMed

    Milanović, Vesna; Comitini, Francesca; Ciani, Maurizio

    2013-02-15

    The yeast communities colonising grape berry surfaces were evaluated for the influence of fungicide treatments in an organic vineyard (copper/sulphur-based products) and a conventional vineyard (commonly used fungicides). Analysis of yeast abundance and diversity was carried out on grape berries and juice during fermentation, using culture-dependent and -independent approaches. Yeast abundance was as generally reported for mature grapes and it was slight higher from grapes treated with conventional fungicides. Initial grape samples showed less yeast species diversity in the organic vineyard compared with the conventional one. In both vineyards, the dominant yeast were Candida zemplinina and Hanseniaspora uvarum (>50%), respectively, typical species that colonise surfaces of mature grape berries. Metschnikowia pulcherrima was widely found in the conventional samples while it was only occasionally found in organic ones. Saccharomyces cerevisiae was isolated only at the end of natural fermentation (conducted in sterile condition), with lower levels in the organic samples. S. cerevisiae strains showed less intraspecies diversity in the organic samples (two genotypes), in comparison with the conventional samples (six genotypes).

  4. Responses of Yeast Biocontrol Agents to Environmental Stress

    PubMed Central

    Sui, Yuan; Wisniewski, Michael; Droby, Samir

    2015-01-01

    Biological control of postharvest diseases, utilizing wild species and strains of antagonistic yeast species, is a research topic that has received considerable attention in the literature over the past 30 years. In principle, it represents a promising alternative to chemical fungicides for the management of postharvest decay of fruits, vegetables, and grains. A yeast-based biocontrol system is composed of a tritrophic interaction between a host (commodity), a pathogen, and a yeast species, all of which are affected by environmental factors such as temperature, pH, and UV light as well as osmotic and oxidative stresses. Additionally, during the production process, biocontrol agents encounter various severe abiotic stresses that also impact their viability. Therefore, understanding the ecological fitness of the potential yeast biocontrol agents and developing strategies to enhance their stress tolerance are essential to their efficacy and commercial application. The current review provides an overview of the responses of antagonistic yeast species to various environmental stresses, the methods that can be used to improve stress tolerance and efficacy, and the related mechanisms associated with improved stress tolerance. PMID:25710368

  5. [Synthesis of melanin pigments by Antarctic black yeast].

    PubMed

    Tashirev, A B; Romanovskaia, V A; Rokitko, P V; Matveeva, N A; Shilin, S O; Tashireva, A A

    2012-01-01

    Five strains of the black yeast similar to Exophiala nigra (Nadsoniela nigra), which we have isolated from the Antarctic biotopes, are studied. At cultivation in a periodic operation the maximum level of absolutely dry biomass in five tested strains constituted 3.2-7.8 g/l of medium, melanin pigment yield being 6-9% of absolutely dry mass of cells. Two highly productive strains have been selected. Pigments of the studied black yeast are water-insoluble, however dissolve in alkali and concentrated acids. The maximum absorption of the yeast pigments was in the range of 220 nm. The above-stated properties of pigments of the investigated yeast correspond to the description of melanin fractions of Nadsoniela nigra and some microscopic mushrooms. The water-soluble melanin-pigments have been obtained after the dialysis of alkaline solution of the pigment. UV-spectra and visible absorption spectra of water solution of melanin-pigments are almost identical to those of initial alkaline solutions. It is shown that the studied yeast are resistant to high concentrations of toxic metals (Hg2+, Cu2+, Co2+, Cr(VI) and Ni2+), and introduction of Co2+ into the cultivation medium leads to the increase of pigments synthesis.

  6. Phenol degradation and heavy metal tolerance of Antarctic yeasts.

    PubMed

    Fernández, Pablo Marcelo; Martorell, María Martha; Blaser, Mariana G; Ruberto, Lucas Adolfo Mauro; de Figueroa, Lucía Inés Castellanos; Mac Cormack, Walter Patricio

    2017-03-07

    In cold environments, biodegradation of organic pollutants and heavy metal bio-conversion requires the activity of cold-adapted or cold-tolerant microorganisms. In this work, the ability to utilize phenol, methanol and n-hexadecane as C source, the tolerance to different heavy metals and growth from 5 to 30 °C were evaluated in cold-adapted yeasts isolated from Antarctica. Fifty-nine percent of the yeasts were classified as psychrotolerant as they could grow in all the range of temperature tested, while the other 41% were classified as psychrophilic as they only grew below 25 °C. In the assimilation tests, 32, 78, and 13% of the yeasts could utilize phenol, n-hexadecane, and methanol as C source, respectively, but only 6% could assimilate the three C sources evaluated. In relation to heavy metals ions, 55, 68, and 80% were tolerant to 1 mM of Cr(VI), Cd(II), and Cu(II), respectively. Approximately a half of the isolates tolerated all of them. Most of the selected yeasts belong to genera previously reported as common for Antarctic soils, but several other genera were also isolated, which contribute to the knowledge of this cold environment mycodiversity. The tolerance to heavy metals of the phenol-degrading cold-adapted yeasts illustrated that the strains could be valuable as inoculant for cold wastewater treatment in extremely cold environments.

  7. Yeast Prions: Structure, Biology, and Prion-Handling Systems

    PubMed Central

    Shewmaker, Frank P.; Bateman, David A.; Edskes, Herman K.; Gorkovskiy, Anton; Dayani, Yaron; Bezsonov, Evgeny E.

    2015-01-01

    SUMMARY A prion is an infectious protein horizontally transmitting a disease or trait without a required nucleic acid. Yeast and fungal prions are nonchromosomal genes composed of protein, generally an altered form of a protein that catalyzes the same alteration of the protein. Yeast prions are thus transmitted both vertically (as genes composed of protein) and horizontally (as infectious proteins, or prions). Formation of amyloids (linear ordered β-sheet-rich protein aggregates with β-strands perpendicular to the long axis of the filament) underlies most yeast and fungal prions, and a single prion protein can have any of several distinct self-propagating amyloid forms with different biological properties (prion variants). Here we review the mechanism of faithful templating of protein conformation, the biological roles of these prions, and their interactions with cellular chaperones, the Btn2 and Cur1 aggregate-handling systems, and other cellular factors governing prion generation and propagation. Human amyloidoses include the PrP-based prion conditions and many other, more common amyloid-based diseases, several of which show prion-like features. Yeast prions increasingly are serving as models for the understanding and treatment of many mammalian amyloidoses. Patients with different clinical pictures of the same amyloidosis may be the equivalent of yeasts with different prion variants. PMID:25631286

  8. Yeast prions: structure, biology, and prion-handling systems.

    PubMed

    Wickner, Reed B; Shewmaker, Frank P; Bateman, David A; Edskes, Herman K; Gorkovskiy, Anton; Dayani, Yaron; Bezsonov, Evgeny E

    2015-03-01

    A prion is an infectious protein horizontally transmitting a disease or trait without a required nucleic acid. Yeast and fungal prions are nonchromosomal genes composed of protein, generally an altered form of a protein that catalyzes the same alteration of the protein. Yeast prions are thus transmitted both vertically (as genes composed of protein) and horizontally (as infectious proteins, or prions). Formation of amyloids (linear ordered β-sheet-rich protein aggregates with β-strands perpendicular to the long axis of the filament) underlies most yeast and fungal prions, and a single prion protein can have any of several distinct self-propagating amyloid forms with different biological properties (prion variants). Here we review the mechanism of faithful templating of protein conformation, the biological roles of these prions, and their interactions with cellular chaperones, the Btn2 and Cur1 aggregate-handling systems, and other cellular factors governing prion generation and propagation. Human amyloidoses include the PrP-based prion conditions and many other, more common amyloid-based diseases, several of which show prion-like features. Yeast prions increasingly are serving as models for the understanding and treatment of many mammalian amyloidoses. Patients with different clinical pictures of the same amyloidosis may be the equivalent of yeasts with different prion variants.

  9. Genome sequence of the lager brewing yeast, an interspecies hybrid.

    PubMed

    Nakao, Yoshihiro; Kanamori, Takeshi; Itoh, Takehiko; Kodama, Yukiko; Rainieri, Sandra; Nakamura, Norihisa; Shimonaga, Tomoko; Hattori, Masahira; Ashikari, Toshihiko

    2009-04-01

    This work presents the genome sequencing of the lager brewing yeast (Saccharomyces pastorianus) Weihenstephan 34/70, a strain widely used in lager beer brewing. The 25 Mb genome comprises two nuclear sub-genomes originating from Saccharomyces cerevisiae and Saccharomyces bayanus and one circular mitochondrial genome originating from S. bayanus. Thirty-six different types of chromosomes were found including eight chromosomes with translocations between the two sub-genomes, whose breakpoints are within the orthologous open reading frames. Several gene loci responsible for typical lager brewing yeast characteristics such as maltotriose uptake and sulfite production have been increased in number by chromosomal rearrangements. Despite an overall high degree of conservation of the synteny with S. cerevisiae and S. bayanus, the syntenies were not well conserved in the sub-telomeric regions that contain lager brewing yeast characteristic and specific genes. Deletion of larger chromosomal regions, a massive unilateral decrease of the ribosomal DNA cluster and bilateral truncations of over 60 genes reflect a post-hybridization evolution process. Truncations and deletions of less efficient maltose and maltotriose uptake genes may indicate the result of adaptation to brewing. The genome sequence of this interspecies hybrid yeast provides a new tool for better understanding of lager brewing yeast behavior in industrial beer production.

  10. Nuclear Magnetic Resonance Spectroscopy-Based Identification of Yeast.

    PubMed

    Himmelreich, Uwe; Sorrell, Tania C; Daniel, Heide-Marie

    2017-01-01

    Rapid and robust high-throughput identification of environmental, industrial, or clinical yeast isolates is important whenever relatively large numbers of samples need to be processed in a cost-efficient way. Nuclear magnetic resonance (NMR) spectroscopy generates complex data based on metabolite profiles, chemical composition and possibly on medium consumption, which can not only be used for the assessment of metabolic pathways but also for accurate identification of yeast down to the subspecies level. Initial results on NMR based yeast identification where comparable with conventional and DNA-based identification. Potential advantages of NMR spectroscopy in mycological laboratories include not only accurate identification but also the potential of automated sample delivery, automated analysis using computer-based methods, rapid turnaround time, high throughput, and low running costs.We describe here the sample preparation, data acquisition and analysis for NMR-based yeast identification. In addition, a roadmap for the development of classification strategies is given that will result in the acquisition of a database and analysis algorithms for yeast identification in different environments.

  11. Ceramide triggers metacaspase-independent mitochondrial cell death in yeast.

    PubMed

    Carmona-Gutierrez, Didac; Reisenbichler, Angela; Heimbucher, Petra; Bauer, Maria A; Braun, Ralf J; Ruckenstuhl, Christoph; Büttner, Sabrina; Eisenberg, Tobias; Rockenfeller, Patrick; Fröhlich, Kai-Uwe; Kroemer, Guido; Madeo, Frank

    2011-11-15

    The activation of ceramide-generating enzymes, the blockade of ceramide degradation, or the addition of ceramide analogues can trigger apoptosis or necrosis in human cancer cells. Moreover, endogenous ceramide plays a decisive role in the killing of neoplastic cells by conventional anticancer chemotherapeutics. Here, we explored the possibility that membrane-permeable C2-ceramide might kill budding yeast (Saccharomyces cerevisiae) cells under fermentative conditions, where they exhibit rapid proliferation and a Warburg-like metabolism that is reminiscent of cancer cells. C2-ceramide efficiently induced the generation of reactive oxygen species (ROS), as well as apoptotic and necrotic cell death, and this effect was not influenced by deletion of the sole yeast metacaspase. However, C2-ceramide largely failed to cause ROS hypergeneration and cell death upon deletion of the mitochondrial genome. Thus, mitochondrial function is strictly required for C2-ceramide-induced yeast lethality. Accordingly, mitochondria from C2-ceramide-treated yeast cells exhibited major morphological alterations including organelle fragmentation and aggregation. Altogether, our results point to a pivotal role of mitochondria in ceramide-induced yeast cell death.

  12. The yeast Saccharomyces cerevisiae- the main character in beer brewing.

    PubMed

    Lodolo, Elizabeth J; Kock, Johan L F; Axcell, Barry C; Brooks, Martin

    2008-11-01

    Historically, mankind and yeast developed a relationship that led to the discovery of fermented beverages. Numerous inventions have led to improved technologies and capabilities to optimize fermentation technology on an industrial scale. The role of brewing yeast in the beer-making process is reviewed and its importance as the main character is highlighted. On considering the various outcomes of functions in a brewery, it has been found that these functions are focused on supporting the supply of yeast requirements for fermentation and ultimately to maintain the integrity of the product. The functions/processes include: nutrient supply to the yeast (raw material supply for brewhouse wort production); utilities (supply of water, heat and cooling); quality assurance practices (hygiene practices, microbiological integrity measures and other specifications); plant automation (vessels, pipes, pumps, valves, sensors, stirrers and centrifuges); filtration and packaging (product preservation until consumption); distribution (consumer supply); and marketing (consumer awareness). Considering this value chain of beer production and the 'bottle neck' during production, the spotlight falls on fermentation, the age-old process where yeast transforms wort into beer.

  13. Immobilized yeast bioreactor systems for continuous beer fermentation

    PubMed

    Tata; Bower; Bromberg; Duncombe; Fehring; Lau; Ryder; Stassi

    1999-01-01

    Two different types of immobilized yeast bioreactors were examined for continuous fermentation of high-gravity worts. One of these is a fluidized bed reactor (FBR) that employs porous glass beads for yeast immobilization. The second system is a loop reactor containing a porous silicon carbide cartridge (SCCR) for immobilizing the yeast cells. Although there was some residual fermentable sugar in the SCCR system product, nearly complete attenuation of the wort sugars was achieved in either of the systems when operated as a two-stage process. Fermentation could be completed in these systems in only half the time required for a conventional batch process. Both the systems showed similar kinetics of extract consumption, and therefore similar volumetric productivity. As compared to the batch fermentation, total fusel alcohols were lower; total esters, while variable, were generally higher. The yeast biomass production was similar to that in a conventional fermentation process. As would be expected in an accelerated fermentation system, the levels of vicinal diketones (VDKs) were higher. To remove the VDKs, the young beer was heat-treated to convert the VDK precursors and processed through a packed bed immobilized yeast bioreactor for VDK assimilation. The finished product from the FBR system was found to be quite acceptable from a flavor perspective, albeit different from the product from a conventional batch process. Significantly shortened fermentation times demonstrate the feasibility of this technology for beer production.

  14. The Yeast Copper Response Is Regulated by DNA Damage

    PubMed Central

    Dong, Kangzhen; Addinall, Stephen G.; Lydall, David

    2013-01-01

    Copper is an essential but potentially toxic redox-active metal, so the levels and distribution of this metal are carefully regulated to ensure that it binds to the correct proteins. Previous studies of copper-dependent transcription in the yeast Saccharomyces cerevisiae have focused on the response of genes to changes in the exogenous levels of copper. We now report that yeast copper genes are regulated in response to the DNA-damaging agents methyl methanesulfonate (MMS) and hydroxyurea by a mechanism(s) that requires the copper-responsive transcription factors Mac1 and AceI, copper superoxide dismutase (Sod1) activity, and the Rad53 checkpoint kinase. Furthermore, in copper-starved yeast, the response of the Rad53 pathway to MMS is compromised due to a loss of Sod1 activity, consistent with the model that yeast imports copper to ensure Sod1 activity and Rad53 signaling. Crucially, the Mac1 transcription factor undergoes changes in its redox state in response to changing levels of copper or MMS. This study has therefore identified a novel regulatory relationship between cellular redox, copper homeostasis, and the DNA damage response in yeast. PMID:23959798

  15. Screening wild yeast strains for alcohol fermentation from various fruits.

    PubMed

    Lee, Yeon-Ju; Choi, Yu-Ri; Lee, So-Young; Park, Jong-Tae; Shim, Jae-Hoon; Park, Kwan-Hwa; Kim, Jung-Wan

    2011-03-01

    Wild yeasts on the surface of various fruits including grapes were surveyed to obtain yeast strains suitable for fermenting a novel wine with higher alcohol content and supplemented with rice starch. We considered selected characteristics, such as tolerance to alcohol and osmotic pressure, capability of utilizing maltose, and starch hydrolysis. Among 637 putative yeast isolates, 115 strains exhibiting better growth in yeast-peptone-dextrose broth containing 30% dextrose, 7% alcohol, or 2% maltose were selected, as well as five α-amylase producers. Nucleotide sequence analysis of the 26S rDNA gene classified the strains into 13 species belonging to five genera; Pichia anomala was the most prevalent (41.7%), followed by Wickerhamomyces anomalus (19.2%), P. guilliermondii (15%), Candida spp. (5.8%), Kodamaea ohmeri (2.5%), and Metschnikowia spp. (2.5%). All of the α-amylase producers were Aureobasidium pullulans. Only one isolate (NK28) was identified as Saccharomyces cerevisiae. NK28 had all of the desired properties for the purpose of this study, except α-amylase production, and fermented alcohol better than commercial wine yeasts.

  16. Screening Wild Yeast Strains for Alcohol Fermentation from Various Fruits

    PubMed Central

    Lee, Yeon-Ju; Choi, Yu-Ri; Lee, So-Young; Park, Jong-Tae; Shim, Jae-Hoon; Park, Kwan-Hwa

    2011-01-01

    Wild yeasts on the surface of various fruits including grapes were surveyed to obtain yeast strains suitable for fermenting a novel wine with higher alcohol content and supplemented with rice starch. We considered selected characteristics, such as tolerance to alcohol and osmotic pressure, capability of utilizing maltose, and starch hydrolysis. Among 637 putative yeast isolates, 115 strains exhibiting better growth in yeast-peptone-dextrose broth containing 30% dextrose, 7% alcohol, or 2% maltose were selected, as well as five α-amylase producers. Nucleotide sequence analysis of the 26S rDNA gene classified the strains into 13 species belonging to five genera; Pichia anomala was the most prevalent (41.7%), followed by Wickerhamomyces anomalus (19.2%), P. guilliermondii (15%), Candida spp. (5.8%), Kodamaea ohmeri (2.5%), and Metschnikowia spp. (2.5%). All of the α-amylase producers were Aureobasidium pullulans. Only one isolate (NK28) was identified as Saccharomyces cerevisiae. NK28 had all of the desired properties for the purpose of this study, except α-amylase production, and fermented alcohol better than commercial wine yeasts. PMID:22783070

  17. Technological properties of bakers' yeasts in durum wheat semolina dough.

    PubMed

    Giannone, Virgilio; Longo, Chiara; Damigella, Arcangelo; Raspagliesi, Domenico; Spina, Alfio; Palumbo, Massimo

    2010-04-01

    Properties of 13 Saccharomyces cerevisiae strains isolated from different sources (traditional sourdoughs, industrial baking yeasts etc.) were studied in dough produced with durum wheat (Sicilian semolina, variety Mongibello). Durum wheat semolina and durum wheat flour are products prepared from grain of durum wheat (Triticum durum Desf.) by grinding or milling processes in which the bran and germ are essentially removed and the remainder is comminuted to a suitable degree of fineness. Acidification and leavening properties of the dough were evaluated. Strains isolated from traditional sourdoughs (DSM PST18864, DSM PST18865 and DSM PST18866) showed higher leavening power, valuable after the first and second hours of fermentation, than commercial baking yeasts. In particular the strain DSM PST 18865 has also been successfully tested in bakery companies for the improvement of production processes. Baking and staling tests were carried out on five yeast strains to evaluate their fermentation ability directly and their resistance to the staling process. Amplified fragment length polymorphism (fAFLP) was used to investigate genetic variations in the yeast strains. This study showed an appreciable biodiversity in the microbial populations of both wild and commercial yeast strains.

  18. Carbonation acceleration of calcium hydroxide nanoparticles: induced by yeast fermentation

    NASA Astrophysics Data System (ADS)

    Lopez-Arce, Paula; Zornoza-Indart, Ainara

    2015-09-01

    Carbonation of Ca(OH)2 nanoparticles and consolidation of limestone are accelerated by high humidity and a yeast fermentation system that supplies a saturated atmosphere on CO2, H2O vapor and ethanol during 28 days. Nanoparticles were analyzed by X-ray diffraction and differential thermal analyses with thermogravimetry. Spectrophotometry, scanning electron microscopy analyses, and hydric and mechanical tests were also performed in stones specimens. Samples exposed to the yeast environment achieve 100 % relative CaCO3 yield, whereas at high humidity but without the yeast and under laboratory environment, relative yields of 95 % CaCO3 and 15 % CaCO3 are, respectively, reached, with white crusts and glazing left on the stone surfaces when the nanoparticles are applied at a concentration of 25 g/l. The largest increase in the drilling resistance and surface hardness values with slight increase in the capillarity absorption and desorption coefficients and with lesser stone color changes are produced at a concentration of 5 g/l, in the yeast system environment. This especially happens in stone specimens initially with bimodal pore size distributions, more amounts of pores with diameters between 0.1 and 1 µm, higher open porosity values and faster capillary coefficients. An inexpensive and reliable method based on water and yeast-sugar solution is presented to speed up carbonation of Ca(OH)2 nanoparticles used as a consolidating product to improve the mechanical properties of decayed limestone from archaeological and architectural heritage.

  19. Dimethyl sulfoxide induces oxidative stress in the yeast Saccharomyces cerevisiae.

    PubMed

    Sadowska-Bartosz, Izabela; Pączka, Aleksandra; Mołoń, Mateusz; Bartosz, Grzegorz

    2013-12-01

    Dimethyl sulfoxide (DMSO) is used as a cryoprotectant for the preservation of cells, including yeast, and as a solvent for chemical compounds. We report that DMSO induces oxidative stress in the yeast. Saccharomyces cerevisiae wt strain EG-103 and its mutants Δsod1, Δsod2, and Δsod1 Δsod2 were used. Yeast were subjected to the action of 1-14% DMSO for 1 h at 28 °C. DMSO induced a concentration-dependent inhibition of yeast growth, the effect being more pronounced for mutants devoid of SOD (especially Δsod1 Δsod2). Cell viability was compromised. DMSO-concentration-dependent activity loss of succinate dehydrogenase, a FeS enzyme sensitive to oxidative stress, was observed. DMSO enhanced formation of reactive oxygen species, estimated with dihydroethidine in a concentration-dependent manner, the effect being again more pronounced in mutants devoid of superoxide dismutases. The content of cellular glutathione was increased with increasing DMSO concentrations, which may represent a compensatory response. Membrane fluidity, estimated by fluorescence polarization of DPH, was decreased by DMSO. These results demonstrate that DMSO, although generally considered to be antioxidant, induces oxidative stress in yeast cells.

  20. Tolerance of budding yeast Saccharomyces cerevisiae to ultra high pressure

    NASA Astrophysics Data System (ADS)

    Ono, Fumihisa; Shibata, Michiko; Torigoe, Motoki; Matsumoto, Yuta; Yamamoto, Shinsuke; Takizawa, Noboru; Hada, Yoshio; Mori, Yoshihisa; Takarabe, Kenichi

    2013-06-01

    In our previous studies on the tolerance of small plants and animals to the high hydrostatic pressure of 7.5 GPa, it was shown that all the living samples could be borne at this high pressure, which is more than one order of magnitude higher than the proteinic denaturation pressure. To make this inconsistency clear, we have extended these studies to a smaller sized fungus, budding yeast Saccharomyces cerevisiae. A several pieces of budding yeast (dry yeast) were sealed in a small teflon capsule with a liquid pressure medium fluorinate (PC72, Sumitomo 3M), and exposed to 7.5 GPa by using a cubic anvil press. The pressure was kept constant for various duration of time from 2 to 24 h. After the pressure was released, the specimens were brought out from the teflon capsule, and they were cultivated on a potato dextrose agar (PDA). It was found that the budding yeast exposed to 7.5 GPa for up to 6 h showed multiplication. However, those exposed to 7.5 GPa for 12 and 24 h were found dead. The high pressure tolerance of budding yeast is weaker than that of tardigrades.

  1. Dietary glucose regulates yeast consumption in adult Drosophila males

    PubMed Central

    Lebreton, Sébastien; Witzgall, Peter; Olsson, Marie; Becher, Paul G.

    2014-01-01

    The adjustment of feeding behavior in response to hunger and satiety contributes to homeostatic regulation in animals. The fruit fly Drosophila melanogaster feeds on yeasts growing on overripe fruit, providing nutrients required for adult survival, reproduction and larval growth. Here, we present data on how the nutritional value of food affects subsequent yeast consumption in Drosophila adult males. After a period of starvation, flies showed intensive yeast consumption. In comparison, flies stopped feeding after having access to a nutritive cornmeal diet. Interestingly, dietary glucose was equally efficient as the complex cornmeal diet. In contrast, flies fed with sucralose, a non-metabolizable sweetener, behaved as if they were starved. The adipokinetic hormone and insulin-like peptides regulate metabolic processes in insects. We did not find any effect of the adipokinetic hormone pathway on this modulation. Instead, the insulin pathway was involved in these changes. Flies lacking the insulin receptor (InR) did not respond to nutrient deprivation by increasing yeast consumption. Together these results show the importance of insulin in the regulation of yeast consumption in response to starvation in adult D. melanogaster males. PMID:25566097

  2. Evolutionary Role of Interspecies Hybridization and Genetic Exchanges in Yeasts

    PubMed Central

    Dujon, Bernard

    2012-01-01

    Summary: Forced interspecific hybridization has been used in yeasts for many years to study speciation or to construct artificial strains with novel fermentative and metabolic properties. Recent genome analyses indicate that natural hybrids are also generated spontaneously between yeasts belonging to distinct species, creating lineages with novel phenotypes, varied genetic stability, or altered virulence in the case of pathogens. Large segmental introgressions from evolutionarily distant species are also visible in some yeast genomes, suggesting that interspecific genetic exchanges occur during evolution. The origin of this phenomenon remains unclear, but it is likely based on weak prezygotic barriers, limited Dobzhansky-Muller (DM) incompatibilities, and rapid clonal expansions. Newly formed interspecies hybrids suffer rapid changes in the genetic contribution of each parent, including chromosome loss or aneuploidy, translocations, and loss of heterozygosity, that, except in a few recently studied cases, remain to be characterized more precisely at the genomic level by use of modern technologies. We review here known cases of natural or artificially formed interspecies hybrids between yeasts and discuss their potential importance in terms of genome evolution. Problems of meiotic fertility, ploidy constraint, gene and gene product compatibility, and nucleomitochondrial interactions are discussed and placed in the context of other known mechanisms of yeast genome evolution as a model for eukaryotes. PMID:23204364

  3. Phylogenetic Relationships Matter: Antifungal Susceptibility among Clinically Relevant Yeasts

    PubMed Central

    Schmalreck, A. F.; Becker, K.; Fegeler, W.; Czaika, V.; Ulmer, H.; Lass-Flörl, C.

    2014-01-01

    The objective of this study was 2-fold: to evaluate whether phylogenetically closely related yeasts share common antifungal susceptibility profiles (ASPs) and whether these ASPs can be predicted from phylogeny. To address this question, 9,627 yeast strains were collected and tested for their antifungal susceptibility. Isolates were reidentified by considering recent changes in taxonomy and nomenclature. A phylogenetic (PHYLO) code based on the results of multilocus sequence analyses (large-subunit rRNA, small-subunit rRNA, translation elongation factor 1α, RNA polymerase II subunits 1 and 2) and the classification of the cellular neutral sugar composition of coenzyme Q and 18S ribosomal DNA was created to group related yeasts into PHYLO groups. The ASPs were determined for fluconazole, itraconazole, and voriconazole in each PHYLO group. The majority (95%) of the yeast strains were Ascomycetes. After reclassification, a total of 23 genera and 54 species were identified, resulting in an increase of 64% of genera and a decrease of 5% of species compared with the initial identification. These taxa were assigned to 17 distinct PHYLO groups (Ascomycota, n = 13; Basidiomycota, n = 4). ASPs for azoles were similar among members of the same PHYLO group and different between the various PHYLO groups. Yeast phylogeny may be an additional tool to significantly enhance the assessment of MIC values and to predict antifungal susceptibility, thereby more rapidly initiating appropriate patient management. PMID:24366735

  4. Diversity of soil yeasts isolated from South Victoria Land, Antarctica

    USGS Publications Warehouse

    Connell, L.; Redman, R.; Craig, S.; Scorzetti, G.; Iszard, M.; Rodriguez, R.

    2008-01-01

    Unicellular fungi, commonly referred to as yeasts, were found to be components of the culturable soil fungal population in Taylor Valley, Mt. Discovery, Wright Valley, and two mountain peaks of South Victoria Land, Antarctica. Samples were taken from sites spanning a diversity of soil habitats that were not directly associated with vertebrate activity. A large proportion of yeasts isolated in this study were basidiomycetous species (89%), of which 43% may represent undescribed species, demonstrating that culturable yeasts remain incompletely described in these polar desert soils. Cryptococcus species represented the most often isolated genus (33%) followed by Leucosporidium (22%). Principle component analysis and multiple linear regression using stepwise selection was used to model the relation between abiotic variables (principle component 1 and principle component 2 scores) and yeast biodiversity (the number of species present at a given site). These analyses identified soil pH and electrical conductivity as significant predictors of yeast biodiversity. Species-specific PCR primers were designed to rapidly discriminate among the Dioszegia and Leucosporidium species collected in this study. ?? 2008 Springer Science+Business Media, LLC.

  5. Cellular and molecular effects of yeast probiotics on cancer.

    PubMed

    Saber, Amir; Alipour, Beitollah; Faghfoori, Zeinab; Yari Khosroushahi, Ahmad

    2017-02-01

    The cancer is one of the main causes of human deaths worldwide. The exact mechanisms of initiation and progression of malignancies are not clear yet, but there is a common agreement about the role of colonic microbiota in the etiology of different cancers. Probiotics have been examined for their anti-cancer effects, and different mechanisms have been suggested about their antitumor functions. Nonpathogenic yeasts, as members of probiotics family, can be effective on gut microbiota dysbiosis. Generally safe yeasts have shown so many beneficial effects on human health. Probiotic yeasts influence physiology, metabolism, and immune homeostasis in the colon and contribute to cancer treatment due to possessing anti-inflammatory, anti-proliferative and anti-cancer properties. This study reviews some of the health-beneficial effects of probiotic yeasts and their biological substances like folic acid and β-glucan on cancer and focuses on the possible cellular and molecular mechanisms of probiotic yeasts such as influencing pathogenic bacteria, inactivation of carcinogenic compounds, especially those derived from food, improvement of intestinal barrier function, modulation of immune responses, antitoxic function, apoptosis, and anti-proliferative effects.

  6. A laboratory yeast strain suitable for spirit production.

    PubMed

    Schehl, Beatus; Müller, Christine; Senn, Thomas; Heinisch, Jürgen J

    2004-12-01

    Yeast strains of the species Saccharomyces cerevisiae currently in use for the production of consumable alcohols such as beer, wine and spirits are genetically largely undefined. This prevents the use of standard genetic manipulations, such as crossings and tetrad analysis, for strain improvement. Furthermore, it complicates the application of the majority of modern methods developed in yeast molecular biology. Here we used two haploid laboratory strains with suitable auxotrophic markers for the construction of a genetically well defined, prototrophic diploid production strain. This strain was tested for its fermentative and sensory performances in comparison to commercially available yeasts. Three different fruit mashes (cherries, plums and pears) were fermented in a 90 kg scale. These were then subjected to distillation and used for the production of spirits with a final ethanol content of 40% (v/v). Fermentation parameters assayed included growth, sugar utilization, ethanol production and generation of volatile compounds, higher alcohols and glycerol. The spirits were also tested for their sensory performances and the data obtained statistically consolidated. Our results clearly demonstrate that this laboratory strain does not display any disadvantage compared with commercial yeasts in spirit production for any of the parameters tested, yet it offers the potential to apply both classical breeding and modern molecular genetic techniques for adjusting yeast physiology to special production schemes.

  7. Transcription of a yeast ribosomal RNA minigene in Saccharomyces cerevisiae.

    PubMed Central

    Quincey, R V; Arnold, R E

    1984-01-01

    A transcription system using intact yeast has been developed for investigating which sequences are implicated in the initiation of transcription of yeast rRNA genes. The system employs an rRNA minigene that consists of the initiation and termination sites for rRNA biosynthesis separated by approx. 700 base pairs of vector DNA in the Escherichia coli-yeast shuttle vector, pJDB207. Two recombinants containing this minigene were constructed; one retained all of the nontranscribed spacer DNA upstream from the initiation site, the other retained 208 base pairs of this DNA. Transcripts of this structurally unique minigene in RNA from yeast transformed with these recombinants were readily detected by nuclease S1 mapping. These transcripts were initiated at the site used by the host rRNA genes, were approx. 3-fold more abundant in the recombinant retaining all of the nontranscribed spacer and were less abundant when the yeast was not growing. Images Fig. 4. Fig. 5. Fig. 6. PMID:6097222

  8. A yeast screen system for aromatase inhibitors and ligands for androgen receptor: yeast cells transformed with aromatase and androgen receptor.

    PubMed Central

    Mak, P; Cruz, F D; Chen, S

    1999-01-01

    Endocrine disruptors are hormone mimics that modify hormonal action in humans and animals. It is thought that some endocrine disruptors modify estrogen and androgen action in humans and animals by suppressing aromatase activity. Aromatase cytochrome P450 is the key enzyme that converts C19 androgens to aromatic C18 estrogenic steroids. We have developed a novel aromatase inhibitor screening method that allows us to identify antiaromatase activity of various environmental chemicals. The screen was developed by coexpressing the human aromatase and the mouse androgen receptor in yeast cells, which carry the androgen-responsive ss-galactosidase reporter plasmid. Functional expression of aromatase in yeast has been demonstrated using the [3H]-water release assay with intact cells as well as with yeast microsomes. The aromatase activity could be blocked by known aromatase inhibitors such as aminoglutethimide (AG). Yeast-produced androgen receptors were able to transactivate a yeast basal promoter linked to an androgen-responsive element in response to androgens. The resultant triple yeast transformant responded to the treatment of testosterone, androstenedione, or 5 alpha-dihydrotestosterone (5 alpha-DHT). In the absence of the aromatase inhibitor AG, transcriptional activation was observed only for the nonaromatizable androgen 5 alpha-DHT. However, the two aromatizable androgens (testosterone and androstenedione) induced the reporter activity in the presence of AG. Using this yeast-based assay, we confirmed that two flavones, chrysin and alpha-naphtholflavone, are inhibitors of aromatase. Thus, this yeast system allows us to develop a high-throughput screening method, without using radioactive substrate, to identify aromatase inhibitors as well as new ligands (nonaromatizable androgen mimics) for the androgen receptors. In addition, this screening method also allows us to distinguish nonandrogenic aromatase inhibitors from inhibitors with androgenic activity. This yeast

  9. Production of fermentation aroma compounds by Saccharomyces cerevisiae wine yeasts: effects of yeast assimilable nitrogen on two model strains.

    PubMed

    Carrau, Francisco M; Medina, Karina; Farina, Laura; Boido, Eduardo; Henschke, Paul A; Dellacassa, Eduardo

    2008-11-01

    The contribution of yeast fermentation metabolites to the aromatic profile of wine is well documented; however, the biotechnological application of this knowledge, apart from strain selection, is still rather limited and often contradictory. Understanding and modeling the relationship between nutrient availability and the production of desirable aroma compounds by different strains must be one of the main objectives in the selection of industrial yeasts for the beverage and food industry. In order to overcome the variability in the composition of grape juices, we have used a chemically defined model medium for studying yeast physiological behavior and metabolite production in response to nitrogen supplementation so as to identify an appropriate yeast assimilable nitrogen level for strain differentiation. At low initial nitrogen concentrations, strain KU1 produced higher quantities of esters and fatty acids whereas M522 produced higher concentrations of isoacids, gamma-butyrolactone, higher alcohols and 3-methylthio-1-propanol. We propose that although strains KU1 and M522 have a similar nitrogen consumption profile, they represent useful models for the chemical characterization of wine strains in relation to wine quality. The differential production of aroma compounds by the two strains is discussed in relation to their capacity for nitrogen usage and their impact on winemaking. The results obtained here will help to develop targeted metabolic footprinting methods for the discrimination of industrial yeasts.

  10. Sensory input attenuation allows predictive sexual response in yeast

    PubMed Central

    Banderas, Alvaro; Koltai, Mihaly; Anders, Alexander; Sourjik, Victor

    2016-01-01

    Animals are known to adjust their sexual behaviour depending on mate competition. Here we report similar regulation for mating behaviour in a sexual unicellular eukaryote, the budding yeast Saccharomyces cerevisiae. We demonstrate that pheromone-based communication between the two mating types, coupled to input attenuation by recipient cells, enables yeast to robustly monitor relative mate abundance (sex ratio) within a mixed population and to adjust their commitment to sexual reproduction in proportion to their estimated chances of successful mating. The mechanism of sex-ratio sensing relies on the diffusible peptidase Bar1, which is known to degrade the pheromone signal produced by mating partners. We further show that such a response to sexual competition within a population can optimize the fitness trade-off between the costs and benefits of mating response induction. Our study thus provides an adaptive explanation for the known molecular mechanism of pheromone degradation in yeast. PMID:27557894

  11. Single-Molecule mRNA Detection in Live Yeast

    PubMed Central

    Lenstra, Tineke L.

    2016-01-01

    Visualization of single RNA molecules in living cells has enabled the study of synthesis, movement, and localization of mRNAs and has provided insight into gene regulation with sub-second temporal resolution and nanometer spatial resolution. Following transcription in single cells indicates that gene activity is heterogeneous between cells and also exhibits random variability over time even within single cells. Studies of mRNAs in yeast can take advantage of the powerful genetics available in this model organism and allow mechanistic questions to be addressed. In this chapter, we describe an approach for visualizing mRNA and transcription in live yeast cells. The method is based on binding of fluorescently labeled MS2 and PP7 coat proteins to stem loops sequences that are introduced into the gene of interest. We give detailed protocols for the construction of the necessary yeast strains, for image acquisition, and for validation. PMID:27110320

  12. Enzymatic initiation of DNA synthesis by yeast DNA polymerases.

    PubMed Central

    Plevani, P; Chang, L M

    1977-01-01

    Partially purified yeast RNA polymerases (RNA nucleotidyltransferases) initiate DNA synthesis by yeast DNA polymerase (DNA nucleotidyltransferase) I and to a lesser extent yeast DNA polymerase II in the replication of single-stranded DNA. The enzymatic initiation of DNA synthesis on phage fd DNA template occurs with dNTPs alone and is further stimulated by the presence of rNTPs in DNA polymerase I reactions. The presence of rNTPs has no effect on the RNA polymerase initiation of the DNA polymerase II reaction. RNA polymerases I and III are more efficient in initiation of DNA synthesis than RNA polymerase II. Analyses of the products of fd DNA replication show noncovalent linkage between the newly synthesized DNA and the template DNA, and covalent linkage between the newly synthesized RNA and DNA. PMID:325562

  13. In vivo genomic footprint of a yeast centromere.

    PubMed Central

    Densmore, L; Payne, W E; Fitzgerald-Hayes, M

    1991-01-01

    We have used in vivo genomic footprinting to investigate the protein-DNA interactions within the conserved DNA elements (CDEI, CDEII, and CDEIII) in the centromere from chromosome III of the yeast Saccharomyces cerevisiae. The in vivo footprint pattern obtained from wild-type cells shows that some guanines within the centromere DNA are protected from methylation by dimethyl sulfate. These results are consistent with studies demonstrating that yeast cells contain sequence-specific centromere DNA-binding proteins. Our in vivo experiments on chromosomes with mutant centromeres show that some mutations which affect chromosome segregation also alter the footprint pattern caused by proteins bound to the centromere DNA. The results of this study provide the first fine-structure map of proteins bound to centromere DNA in living yeast cells and suggest a direct correlation between these protein-DNA interactions and centromere function. Images PMID:1986217

  14. In vitro reconstruction of the mitochondrial translation system of yeast.

    PubMed Central

    Pfisterer, J; Buetow, D E

    1981-01-01

    We have isolated the translation system from yeast mitochondria and have reconstructed it in vitro. This submitochondrial system, composed of mitochondrial ribosomes, tRNA, pH 5 fraction and mRNA, is maximally active at 10 mM Mg2+ and 100 mM KCl or NH4Cl. NH4+ is more stimulatory than K+. Added Escherichia coli tRNA gives less than half the activity obtained with added mitochondrial tRNA. Activity is enhanced with protease inhibitors but not with Ca2+, spermine, or spermidine. In contrast to heterologous translation systems, the present system produces products with molecular weights similar to those of products synthesized by yeast mitochondria in vivo and by intact yeast mitochondria in vitro. The results support the idea that the unique coding features of the mitochondrial genome require a unique translation system for accurate translation of mitochondrial mRNAs. Images PMID:6946437

  15. Diversity and adaptive evolution of Saccharomyces wine yeast: a review

    PubMed Central

    Marsit, Souhir; Dequin, Sylvie

    2015-01-01

    Saccharomyces cerevisiae and related species, the main workhorses of wine fermentation, have been exposed to stressful conditions for millennia, potentially resulting in adaptive differentiation. As a result, wine yeasts have recently attracted considerable interest for studying the evolutionary effects of domestication. The widespread use of whole-genome sequencing during the last decade has provided new insights into the biodiversity, population structure, phylogeography and evolutionary history of wine yeasts. Comparisons between S. cerevisiae isolates from various origins have indicated that a variety of mechanisms, including heterozygosity, nucleotide and structural variations, introgressions, horizontal gene transfer and hybridization, contribute to the genetic and phenotypic diversity of S. cerevisiae. This review will summarize the current knowledge on the diversity and evolutionary history of wine yeasts, focusing on the domestication fingerprints identified in these strains. PMID:26205244

  16. Protein enrichment of potato processing waste through yeast fermentation.

    PubMed

    Gélinas, P; Barrette, J

    2007-03-01

    Potato starch obtained from waste waters of chips manufacturing was used as a fermentation substrate for yeast protein enrichment. Among 18 yeast strains, 6 strains were screened according to their biomass yield and protein content after fermentation for 16 h at 30 degrees C in an aerated glucose-based liquid media (4.5 Ls). Using concentrated media (25% solids) made from potato starch pre-hydrolyzed with malt flour and batch-fermented for 20 h at 26 degrees C under aerobic conditions, Candida utilis ATCC 9256 was the most efficient protein-forming strain. Scaled-up at the 100 Ls level, the aerobic batch process was improved under fed-batch conditions with molasses supplementation. After drying, fermented starch contained 11-12% protein, including 7-8% yeast protein.

  17. QTL mapping of sake brewing characteristics of yeast.

    PubMed

    Katou, Taku; Namise, Masahiro; Kitagaki, Hiroshi; Akao, Takeshi; Shimoi, Hitoshi

    2009-04-01

    A haploid sake yeast strain derived from the commercial diploid sake yeast strain Kyokai no. 7 showed better characteristics for sake brewing compared to the haploid laboratory yeast strain X2180-1B, including higher production of ethanol and aromatic components. A hybrid of these two strains showed intermediate characteristics in most cases. After sporulation of the hybrid strain, we obtained 100 haploid segregants of the hybrid. Small-scale sake brewing tests of these segregants showed a smooth continuous distribution of the sake brewing characteristics, suggesting that these traits are determined by multiple quantitative trait loci (QTLs). To examine these sake brewing characteristics at the genomic level, we performed QTL analysis of sake brewing characteristics using 142 DNA markers that showed heterogeneity between the two parental strains. As a result, we identified 25 significant QTLs involved in the specification of sake brewing characteristics such as ethanol fermentation and the production of aromatic components.

  18. Estimation of population effects in synchronized budding yeast experiments

    NASA Astrophysics Data System (ADS)

    Niemistoe, Antti; Aho, Tommi; Thesleff, Henna; Tiainen, Mikko; Marjanen, Kalle; Linne, Marja-Leena; Yli-Harja, Olli P.

    2003-05-01

    An approach for estimating the distribution of a synchronized budding yeast (Saccharomyces cerevisiae) cell population is discussed. This involves estimation of the phase of the cell cycle for each cell. The approach is based on counting the number of buds of different sizes in budding yeast images. An image processing procedure is presented for the bud-counting task. The procedure employs clustering of the local mean-variance space for segmentation of the images. The subsequent bud-detection step is based on an object separation method which utilizes the chain code representation of objects as well as labeling of connected components. The procedure is tested with microscopic images that were obtained in a time-series experiment of a synchronized budding yeast cell population. The use of the distribution estimate of the cell population for inverse filtering of signals that are obtained in time-series microarray measurements is discussed as well.

  19. Antifungal chitinase against human pathogenic yeasts from Coprinellus congregatus.

    PubMed

    Yoo, Yeeun; Choi, Hyoung T

    2014-05-01

    The inky cap, Coprinellus congregatus, produces mushrooms which become autolyzed rapidly to generate black liquid droplets, in which no cell wall is detected by microscopy. A chitinase (Chi2) which is synthesized during the autolytic phase of C. congregatus inhibits the growths of Candida albicans and Cryptococcus neoformans up to 10% at the concentration of 10 μg/ml, about 50% at concentration of 20 μg/ml, and up to 95% at the concentration of 70 μg/ml. Upon treatment these yeast cells are observed to be severely deformed, with the formation of large holes in the cell wall. The two yeast species show no growth inhibition at the concentration of 5 μg/ml, which means the minimum inhibitory concentrations for both yeast species are 10 μg/ml under these experimental conditions.

  20. Yeast-based microporous carbon materials for carbon dioxide capture.

    PubMed

    Shen, Wenzhong; He, Yue; Zhang, Shouchun; Li, Junfen; Fan, Weibin

    2012-07-01

    A hierarchical microporous carbon material with a Brunauer-Emmett-Teller surface area of 1348 m(2) g(-1) and a pore volume of 0.67 cm(3) g(-1) was prepared from yeast through chemical activation with potassium hydroxide. This type of material contains large numbers of nitrogen-containing groups (nitrogen content >5.3 wt%), and, consequently, basic sites. As a result, this material shows a faster adsorption rate and a higher adsorption capacity of CO(2) than the material obtained by directly carbonizing yeast under the same conditions. The difference is more pronounced in the presence of N(2) or H(2)O, showing that chemical activation of discarded yeast with potassium hydroxide could afford high-performance microporous carbon materials for the capture of CO(2).

  1. Recent Taxonomic Developments with Candida and Other Opportunistic Yeasts.

    PubMed

    Brandt, Mary E; Lockhart, Shawn R

    2012-09-01

    Increases in susceptible patient populations and advances in identification methods have resulted in the continued recognition of novel yeasts as agents of human infection. Most of these agents are members of the well-recognized genera Candida, Cryptococcus, Trichosporon, and Rhodotorula. Some of these agents are "cryptic species," members of species complexes, and may not be detectable using classical carbohydrate assimilation-based methods of yeast identification. Such species require DNA- or MALDI-based methods for correct identification, although sporadic isolates may not routinely require delineation to the individual species level. The coming end of the fungal taxonomy rules requiring separate names for sexual and asexual forms of the same fungus will hopefully allow greater clarity, as names for medically important yeast can now be based on the needs of the medical mycology community and the common goal of better communication between laboratory and clinician.

  2. Genetic Analysis of Haploids from Industrial Strains of Baker's Yeast.

    PubMed

    Oda, Y; Ouchi, K

    1989-07-01

    Strains of baker's yeast conventionally used by the baking industry in Japan were tested for the ability to sporulate and produce viable haploid spores. Three isolates which possessed the properties of baker's yeasts were obtained from single spores. Each strain was a haploid, and one of these strains, YOY34, was characterized. YOY34 fermented maltose and sucrose, but did not utilize galactose, unlike its parental strain. Genetic analysis showed that YOY34 carried two MAL genes, one functional and one cryptic; two SUC genes; and one defective gal gene. The genotype of YOY34 was identified as MATalpha MAL1 MAL3g SUC2 SUC4 gall. The MAL1 gene from this haploid was constitutively expressed, was dominant over other wild-type MAL tester genes, and gave a weak sucrose fermentation. YOY34 was suitable for both bakery products, like conventional baker's yeasts, and for genetic analysis, like laboratory strains.

  3. Synthetic Biology for Engineering Acetyl Coenzyme A Metabolism in Yeast

    PubMed Central

    2014-01-01

    ABSTRACT The yeast Saccharomyces cerevisiae is a widely used cell factory for the production of fuels, chemicals, and pharmaceuticals. The use of this cell factory for cost-efficient production of novel fuels and chemicals requires high yields and low by-product production. Many industrially interesting chemicals are biosynthesized from acetyl coenzyme A (acetyl-CoA), which serves as a central precursor metabolite in yeast. To ensure high yields in production of these chemicals, it is necessary to engineer the central carbon metabolism so that ethanol production is minimized (or eliminated) and acetyl-CoA can be formed from glucose in high yield. Here the perspective of generating yeast platform strains that have such properties is discussed in the context of a major breakthrough with expression of a functional pyruvate dehydrogenase complex in the cytosol. PMID:25370498

  4. Safrole, eugenol and methyleugenol induce intrachromosomal recombination in yeast.

    PubMed

    Schiestl, R H; Chan, W S; Gietz, R D; Mehta, R D; Hastings, P J

    1989-12-01

    Deletion of an integrated plasmid, a specific type of intrachromosomal recombination, was evaluated for inducibility with the phenylpropenes safrole, eugenol and methyleugenol in the yeast Saccharomyces cerevisiae. These phenylpropenes are found in food products, spices, pharmaceuticals and clove cigarettes. Safrole and eugenol are known carcinogens in animals and methyleugenol is a suspected carcinogen. These phenylpropenes are not detectable by the Ames assay and most other short-term tests used currently in predictive carcinogenesis. Like safrole, which has been shown to be nonmutagenic with the Ames assay, eugenol and methyleugenol were found to be nonmutagenic with the Ames assay. In contrast, with the yeast assays which screen for intra- and inter-chromosomal recombination in logarithmic phase cultures, all 3 compounds gave a positive dose-related response. These results demonstrate further that the yeast system can be modified easily to detect various genetic endpoints and that it deserves serious consideration as a test system for predictive carcinogenesis.

  5. [Adaptation of yeasts of the genus Debaryomyces to protocatechuic acid].

    PubMed

    Karasevich, Iu N

    1980-01-01

    Among five yeast strains belonging to the genus Debaryomyces that were unable of utilizing aromatic compounds (phenols and hydroxybenzoic acids), three strains, viz. D. kloeckeri BKM-Y-1044, D. marama BKM-Y-100 and D. marama BKM-Y-2045, were adapted to protocatechuic acid. The adapted yeasts utilized protocatechuic acid if its concentration in the medium was 0.1%, but did not utilize it, or did at a very low rate, if the concentration of protocatechuic acid was decreased to 0.05%. The mechanism of adaptation is rare mutations occurring in succession, and the process takes therefore several months. The adaptation seems to be based on reversion of inactivated genes for enzymes involved in the preparative metabolism of protocatechuic acid. Three typical yeast species of the Debaryomyces genus are proposed (D. hansenii, D. kloeckeri and D. konokotinae) which include all of the Debaryomyces species and strains available at the Institute of Microbiology of the USSR Academy of Sciences.

  6. The development and characterization of synthetic minimal yeast promoters

    PubMed Central

    Redden, Heidi; Alper, Hal S.

    2015-01-01

    Synthetic promoters, especially minimally sized, are critical for advancing fungal synthetic biology. Fungal promoters often span hundreds of base pairs, nearly ten times the amount of bacterial counterparts. This size limits large-scale synthetic biology efforts in yeasts. Here we address this shortcoming by establishing a methodical workflow necessary to identify robust minimal core elements that can be linked with minimal upstream activating sequences to develop short, yet strong yeast promoters. Through a series of library-based synthesis, analysis and robustness tests, we create a set of non-homologous, purely synthetic, minimal promoters for yeast. These promoters are comprised of short core elements that are generic and interoperable and 10 bp UAS elements that impart strong, constitutive function. Through this methodology, we are able to generate the shortest fungal promoters to date, which can achieve high levels of both inducible and constitutive expression with up to an 80% reduction in size. PMID:26183606

  7. How to halve ploidy: lessons from budding yeast meiosis.

    PubMed

    Kerr, Gary William; Sarkar, Sourav; Arumugam, Prakash

    2012-09-01

    Maintenance of ploidy in sexually reproducing organisms requires a specialized form of cell division called meiosis that generates genetically diverse haploid gametes from diploid germ cells. Meiotic cells halve their ploidy by undergoing two rounds of nuclear division (meiosis I and II) after a single round of DNA replication. Research in Saccharomyces cerevisiae (budding yeast) has shown that four major deviations from the mitotic cell cycle during meiosis are essential for halving ploidy. The deviations are (1) formation of a link between homologous chromosomes by crossover, (2) monopolar attachment of sister kinetochores during meiosis I, (3) protection of centromeric cohesion during meiosis I, and (4) suppression of DNA replication following exit from meiosis I. In this review we present the current understanding of the above four processes in budding yeast and examine the possible conservation of molecular mechanisms from yeast to humans.

  8. Patagonian wines: the selection of an indigenous yeast starter.

    PubMed

    Lopes, Christian A; Rodríguez, María E; Sangorrín, Marcela; Querol, Amparo; Caballero, Adriana C

    2007-08-01

    The use of selected yeasts for winemaking has clear advantages over the traditional spontaneous fermentation. The aim of this study was to select an indigenous Saccharomyces cerevisiae yeast isolate in order to develop a regional North Patagonian red wine starter culture. A two-step selection protocol developed according to physiological, technological and ecological criteria based on killer interactions was used. Following this methodology, S. cerevisiae isolate MMf9 was selected among 32 indigenous yeasts previously characterized as belonging to different strains according to molecular patterns and killer biotype. This isolate showed interesting technological and qualitative features including high fermentative power and low volatile acidity production, low foam and low sulphide production, as well as relevant ecological characteristics such as resistance to all indigenous and commercial S. cerevisiae killer strains assayed. Red wines with differential volatile profiles and interesting enological features were obtained at laboratory scale by using this selected indigenous strain.

  9. Whole Genome Analysis of a Wine Yeast Strain

    PubMed Central

    Hauser, Nicole C.; Fellenberg, Kurt; Gil, Rosario; Bastuck, Sonja; Hoheisel, Jörg D.

    2001-01-01

    Saccharomyces cerevisiae strains frequently exhibit rather specific phenotypic features needed for adaptation to a special environment. Wine yeast strains are able to ferment musts, for example, while other industrial or laboratory strains fail to do so. The genetic differences that characterize wine yeast strains are poorly understood, however. As a first search of genetic differences between wine and laboratory strains, we performed DNA-array analyses on the typical wine yeast strain T73 and the standard laboratory background in S288c. Our analysis shows that even under normal conditions, logarithmic growth in YPD medium, the two strains have expression patterns that differ significantly in more than 40 genes. Subsequent studies indicated that these differences correlate with small changes in promoter regions or variations in gene copy number. Blotting copy numbers vs. transcript levels produced patterns, which were specific for the individual strains and could be used for a characterization of unknown samples. PMID:18628902

  10. Aroma formation by immobilized yeast cells in fermentation processes.

    PubMed

    Nedović, V; Gibson, B; Mantzouridou, T F; Bugarski, B; Djordjević, V; Kalušević, A; Paraskevopoulou, A; Sandell, M; Šmogrovičová, D; Yilmaztekin, M

    2015-01-01

    Immobilized cell technology has shown a significant promotional effect on the fermentation of alcoholic beverages such as beer, wine and cider. However, genetic, morphological and physiological alterations occurring in immobilized yeast cells impact on aroma formation during fermentation processes. The focus of this review is exploitation of existing knowledge on the biochemistry and the biological role of flavour production in yeast for the biotechnological production of aroma compounds of industrial importance, by means of immobilized yeast. Various types of carrier materials and immobilization methods proposed for application in beer, wine, fruit wine, cider and mead production are presented. Engineering aspects with special emphasis on immobilized cell bioreactor design, operation and scale-up potential are also discussed. Ultimately, examples of products with improved quality properties within the alcoholic beverages are addressed, together with identification and description of the future perspectives and scope for cell immobilization in fermentation processes.

  11. [The effect of sodium malonate on yeast thermotolerance].

    PubMed

    Rikhvanov, E G; Varakina, N N; Rusaleva, T M; Rachenko, E I; Voĭnikov, V K

    2003-01-01

    The study of the effect of malonate (an inhibitor of the succinate dehydrogenase complex of the respiratory chain of mitochondria) on the thermotolerance of the fermentative Saccharomyces cerevisiae and nonfermentative Rhodotorula rubra yeasts showed that malonate augmented the damaging effect of heat shock on the yeasts utilizing glucose (or other sugars) by means of oxidative phosphorylation. At the same time, malonate did not influence and sometimes even improved the thermotolerance of the yeasts utilizing glucose through fermentation. The suggestion is made that cell tolerance to heat shock depends on the normal functioning of mitochondria. On the other hand, their increased activity at elevated temperatures may accelerate the formation of cytotoxic reactive oxygen species and, hence, is not beneficial to cells.

  12. Relaxation of yeast mitochondrial functions after whole-genome duplication

    PubMed Central

    Jiang, Huifeng; Guan, Wenjun; Pinney, David; Wang, Wen; Gu, Zhenglong

    2008-01-01

    Mitochondria are essential for cellular energy production in most eukaryotic organisms. However, when glucose is abundant, yeast species that underwent whole-genome duplication (WGD) mostly conduct fermentation even under aerobic conditions, and most can survive without a functional mitochondrial genome. In this study, we show that the rate of evolution for the nuclear-encoded mitochondrial genes was greater in post-WGD species than pre-WGD species. Furthermore, codon usage bias was relaxed for these genes in post-WGD yeast species. The codon usage pattern and the distribution of a particular transcription regulatory element suggest that the change to an efficient aerobic fermentation lifestyle in this lineage might have emerged after WGD between the divergence of Kluyveromyces polysporus and Saccharomyces castellii from their common ancestor. This new energy production strategy could have led to the relaxation of mitochondrial function in the relevant yeast species. PMID:18669479

  13. Biomimetic Yeast Cell Typing-Application of QCMs.

    PubMed

    Seidler, Karin; Polreichová, Miroslava; Lieberzeit, Peter A; Dickert, Franz L

    2009-01-01

    Artificial antibodies represent a key factor in the generation of sensing systems for the selective detection of bioanalytes of variable sizes. With biomimetic surfaces, the important model organism Saccharomyces cerevisiae and several of its growth stages may be detected. Quartz crystal microbalances (QCM) with 10 MHz fundamental frequency and coated with polymers imprinted with synchronized yeast cells are presented, which are able to detect duplex cells with high selectivity. Furthermore, a multichannel quartz crystal microbalance (MQCM) was designed and optimized for the measurement in liquids. This one-chip system based on four-electrode geometry allows the simultaneous detection of four analytes and, thus, provides a monitoring system for biotechnology and process control. For further standardization of the method, synthetic stamps containing plastic yeast cells in different growth stages were produced and utilized for imprinting. Mass-sensitive measurements with such MIPs resulted in the same sensor characteristics as obtained for those imprinted with native yeast cells.

  14. In vitro activity of voriconazole against Mexican oral yeast isolates.

    PubMed

    Sánchez Vargas, Luis Octavio; Eraso, Elena; Carrillo-Muñoz, Alfonso Javier; Aguirre, José Manuel; Gaitán-Cepeda, Luis Alberto; Quindós, Guillermo

    2010-05-01

    Oral candidiasis is the most prevalent complication in HIV-infected and AIDS patients. Topical antifungal treatment is useful for the initial episodes of oral candidiasis, but most patients suffer more than one episode and fluconazole or itraconazole can help in the management, and voriconazole may represent a useful alternative agent for the treatment of recalcitrant oral and oesophageal candidiasis. The aim of this research was to study the in vitro activity of voriconazole and fluconazole against Mexican oral isolates of clinically relevant yeast. The in vitro susceptibility of 187 oral yeast isolates from HIV-infected and healthy Mexicans was determined for fluconazole and voriconazole by the M44-A disc diffusion method. At 24 h, fluconazole was active against 179 of 187 isolates (95.7 %). Moreover, a 100% susceptibility to voriconazole was observed. Voriconazole and fluconazole are highly active in vitro against oral yeast isolates. This study provides baseline data on susceptibilities to both antifungal agents in Mexico.

  15. Cross-referencing yeast genetics and mammalian genomes

    SciTech Connect

    Hieter, P.; Basset, D.; Boguski, M.

    1994-09-01

    We have initiated a project that will systematically transfer information about yeast genes onto the genetic maps of mice and human beings. Rapidly expanding human EST data will serve as a source of candidate human homologs that will be repeatedly searched using yeast protein sequence queries. Search results will be automatically reported to participating labs. Human cDNA sequences from which the ESTs are derived will be mapped at high resolution in the human and mouse genomes. The comparative mapping information cross-references the genomic position of novel human cDNAs with functional information known about the cognate yeast genes. This should facilitate the initial identification of genes responsible for mammalian mutant phenotypes, including human disease. In addition, the identification of mammalian homologs of yeast genes provides reagents for determining evolutionary conservation and for performing direct experiments in multicellular eukaryotes to enhance study of the yeast protein`s function. For example, ESTs homologous to CDC27 and CDC16 were identified, and the corresponding cDNA clones were obtained from ATTC, completely sequenced, and mapped on human and mouse chromosomes. In addition, the CDC17hs cDNA has been used to raise antisera to the CDC27Hs protein and used in subcellular localization experiments and junctional studies in mammalian cells. We have received funding from the National Center for Human Genome Research to provide a community resource which will establish comprehensive cross-referencing among yeast, human, and mouse loci. The project is set up as a service and information on how to communicate with this effort will be provided.

  16. Uranium bioprecipitation mediated by yeasts utilizing organic phosphorus substrates.

    PubMed

    Liang, Xinjin; Csetenyi, Laszlo; Gadd, Geoffrey Michael

    2016-06-01

    In this research, we have demonstrated the ability of several yeast species to mediate U(VI) biomineralization through uranium phosphate biomineral formation when utilizing an organic source of phosphorus (glycerol 2-phosphate disodium salt hydrate (C3H7Na2O6P·xH2O (G2P)) or phytic acid sodium salt hydrate (C6H18O24P6·xNa(+)·yH2O (PyA))) in the presence of soluble UO2(NO3)2. The formation of meta-ankoleite (K2(UO2)2(PO4)2·6(H2O)), chernikovite ((H3O)2(UO2)2(PO4)2·6(H2O)), bassetite (Fe(++)(UO2)2(PO4)2·8(H2O)), and uramphite ((NH4)(UO2)(PO4)·3(H2O)) on cell surfaces was confirmed by X-ray diffraction in yeasts grown in a defined liquid medium amended with uranium and an organic phosphorus source, as well as in yeasts pre-grown in organic phosphorus-containing media and then subsequently exposed to UO2(NO3)2. The resulting minerals depended on the yeast species as well as physico-chemical conditions. The results obtained in this study demonstrate that phosphatase-mediated uranium biomineralization can occur in yeasts supplied with an organic phosphate substrate as sole source of phosphorus. Further understanding of yeast interactions with uranium may be relevant to development of potential treatment methods for uranium waste and utilization of organic phosphate sources and for prediction of microbial impacts on the fate of uranium in the environment.

  17. Yeast strains as potential aroma enhancers in dry fermented sausages.

    PubMed

    Flores, Mónica; Corral, Sara; Cano-García, Liliana; Salvador, Ana; Belloch, Carmela

    2015-11-06

    Actual healthy trends produce changes in the sensory characteristics of dry fermented sausages therefore, new strategies are needed to enhance their aroma. In particular, a reduction in the aroma characteristics was observed in reduced fat and salt dry sausages. In terms of aroma enhancing, generally coagulase-negative cocci were selected as the most important group from the endogenous microbiota in the production of flavour compounds. Among the volatile compounds analysed in dry sausages, ester compounds contribute to fruity aroma notes associated with high acceptance of traditional dry sausages. However, the origin of ester compounds in traditional dry sausages can be due to other microorganisms as lactic acid bacteria, yeast and moulds. Yeast contribution in dry fermented sausages was investigated with opposite results attributed to low yeast survival or low activity during processing. Generally, they affect sausage colour and flavour by their oxygen-scavenging and lipolytic activities in addition to, their ability to catabolize fermentation products such as lactate increasing the pH and contributing to less tangy and more aromatic sausages. Recently, the isolation and characterization of yeast from traditional dry fermented sausages made possible the selection of those with ability to produce aroma active compounds. Molecular methods were used for genetic typing of the isolated yeasts whereas their ability to produce aroma compounds was tested in different systems such as in culture media, in model systems and finally on dry fermented sausages. The results revealed that the appropriate selection of yeast strains with aroma potential may be used to improve the sensory characteristics of reformulated fermented sausages.

  18. Yeast identification in floral nectar of Mimulus aurantiacus (Invited)

    NASA Astrophysics Data System (ADS)

    Kyauk, C.; Belisle, M.; Fukami, T.

    2009-12-01

    Nectar is such a sugar-rich resource that serves as a natural habitat in which microbes thrive. As a result, yeasts arrive to nectar on the bodies of pollinators such as hummingbirds and bees. Yeasts use the sugar in nectar for their own needs when introduced. This research focuses on the identification of different types of yeast that are found in the nectar of Mimulus aurantiacus (commonly known as sticky monkey-flower). Unopened Mimulus aurantiacus flower buds were tagged at Jasper Ridge and bagged three days later. Floral nectar was then extracted and plated on potato dextrose agar. Colonies on the plates were isolated and DNA was extracted from each sample using QIAGEN DNeasy Plant Mini Kit. The DNA was amplified through PCR and ran through gel electrophoresis. The PCR product was used to clone the nectar samples into an E.coli vector. Finally, a phylogenetic tree was created by BLAST searching sequences in GenBank using the Internal Transcribed Space (ITS) locus. It was found that 18 of the 50 identified species were Candida magnifica, 14 was Candida rancensis, 6 were Crytococcus albidus and there were 3 or less of the following: Starmella bombicola, Candida floricola, Aureobasidium pullulans, Pichia kluyvera, Metschnikowa cibodaserisis, Rhodotorua colostri, and Malassezia globosa. The low diversity of the yeast could have been due to several factors: time of collection, demographics of Jasper Ridge, low variety of pollinators, and sugar concentration of the nectar. The results of this study serve as a necessary first step for a recently started research project on ecological interactions between plants, pollinators, and nectar-living yeast. More generally, this research studies the use of the nectar-living yeast community as a natural microcosm for addressing basic questions about the role of dispersal and competitive and facilitative interactions in ecological succession.

  19. Automated Segmentation and Classification of High Throughput Yeast Assay Spots

    PubMed Central

    Jafari-Khouzani, Kourosh; Soltanian-Zadeh, Hamid; Fotouhi, Farshad; Parrish, Jodi R.; Finley, Russell L.

    2009-01-01

    Several technologies for characterizing genes and proteins from humans and other organisms use yeast growth or color development as read outs. The yeast two-hybrid assay, for example, detects protein-protein interactions by measuring the growth of yeast on a specific solid medium, or the ability of the yeast to change color when grown on a medium containing a chromogenic substrate. Current systems for analyzing the results of these types of assays rely on subjective and inefficient scoring of growth or color by human experts. Here an image analysis system is described for scoring yeast growth and color development in high throughput biological assays. The goal is to locate the spots and score them in color images of two types of plates named “X-Gal” and “growth assay” plates, with uniformly placed spots (cell areas) on each plate (both plates in one image). The scoring system relies on color for the X-Gal spots, and texture properties for the growth assay spots. A maximum likelihood projection-based segmentation is developed to automatically locate spots of yeast on each plate. Then color histogram and wavelet texture features are extracted for scoring using an optimal linear transformation. Finally an artificial neural network is used to score the X-Gal and growth assay spots using the extracted features. The performance of the system is evaluated using spots of 60 images. After training the networks using training and validation sets, the system was assessed on the test set. The overall accuracies of 95.4% and 88.2% are achieved respectively for scoring the X-Gal and growth assay spots. PMID:17948730

  20. Phenotypic and metabolic traits of commercial Saccharomyces cerevisiae yeasts

    PubMed Central

    2014-01-01

    Currently, pursuing yeast strains that display both a high potential fitness for alcoholic fermentation and a favorable impact on quality is a major goal in the alcoholic beverage industry. This considerable industrial interest has led to many studies characterizing the phenotypic and metabolic traits of commercial yeast populations. In this study, 20 Saccharomyces cerevisiae strains from different geographical origins exhibited high phenotypic diversity when their response to nine biotechnologically relevant conditions was examined. Next, the fermentation fitness and metabolic traits of eight selected strains with a unique phenotypic profile were evaluated in a high-sugar synthetic medium under two nitrogen regimes. Although the strains exhibited significant differences in nitrogen requirements and utilization rates, a direct relationship between nitrogen consumption, specific growth rate, cell biomass, cell viability, acetic acid and glycerol formation was only observed under high-nitrogen conditions. In contrast, the strains produced more succinic acid under the low-nitrogen regime, and a direct relationship with the final cell biomass was established. Glucose and fructose utilization patterns depended on both yeast strain and nitrogen availability. For low-nitrogen fermentation, three strains did not fully degrade the fructose. This study validates phenotypic and metabolic diversity among commercial wine yeasts and contributes new findings on the relationship between nitrogen availability, yeast cell growth and sugar utilization. We suggest that measuring nitrogen during the stationary growth phase is important because yeast cells fermentative activity is not exclusively related to population size, as previously assumed, but it is also related to the quantity of nitrogen consumed during this growth phase. PMID:24949272