yeast get3 suggest: Topics by Science.gov

Sample records for yeast get3 suggest

The ER membrane insertase Get1/2 is required for efficient mitophagy in yeast.

PubMed

Onishi, Mashun; Nagumo, Sachiyo; Iwashita, Shohei; Okamoto, Koji

2018-05-10

Mitophagy is an evolutionarily conserved autophagy pathway that selectively eliminates mitochondria to control mitochondrial quality and quantity. Although mitophagy is thought to be crucial for cellular homeostasis, how this catabolic process is regulated remains largely unknown. Here we demonstrate that mitophagy during prolonged respiratory growth is strongly impaired in yeast cells lacking Get1/2, a transmembrane complex mediating insertion of tail-anchored (TA) proteins into the endoplasmic reticulum (ER) membrane. Under the same conditions, loss of Get1/2 caused only slight defects in other types of selective and bulk autophagy. In addition, mitophagy and other autophagy-related processes are mostly normal in cells lacking Get3, a cytosolic ATP-driven chaperone that promotes delivery of TA proteins to the Get1/2 complex. We also found that Get1/2-deficient cells exhibited wildtype-like induction and mitochondrial localization of Atg32, a protein essential for mitophagy. Notably, Get1/2 is important for Atg32-independent, ectopically promoted mitophagy. Together, we propose that Get1/2-dependent TA protein(s) and/or the Get1/2 complex itself may act specifically in mitophagy. Copyright © 2018 Elsevier Inc. All rights reserved.
The Conserved ATPase Get3/Arr4 Modulates the Activity of Membrane-Associated Proteins in Saccharomyces cerevisiae

PubMed Central

Auld, Kathryn L.; Hitchcock, Amy L.; Doherty, Hugh K.; Frietze, Seth; Huang, Linda S.; Silver, Pamela A.

2006-01-01

The regulation of cellular membrane dynamics is crucial for maintaining proper cell growth and division. The Cdc48-Npl4-Ufd1 complex is required for several regulated membrane-associated processes as part of the ubiquitin–proteasome system, including ER-associated degradation and the control of lipid composition in yeast. In this study we report the results of a genetic screen in Saccharomyces cerevisiae for extragenic suppressors of a temperature-sensitive npl4 allele and the subsequent analysis of one suppressor, GET3/ARR4. The GET3 gene encodes an ATPase with homology to the regulatory component of the bacterial arsenic pump. Mutants of GET3 rescue several phenotypes of the npl4 mutant and transcription of GET3 is coregulated with the proteasome, illustrating a functional relationship between GET3 and NPL4 in the ubiquitin–proteasome system. We have further found that Get3 biochemically interacts with the trans-membrane domain proteins Get1/Mdm39 and Get2/Rmd7 and that Δget3 is able to suppress phenotypes of get1 and get2 mutants, including sporulation defects. In combination, our characterization of GET3 genetic and biochemical interactions with NPL4, GET1, and GET2 implicates Get3 in multiple membrane-dependent pathways. PMID:16816426
Partial purification of histone H3 proteolytic activity from the budding yeast Saccharomyces cerevisiae.

PubMed

Azad, Gajendra Kumar; Tomar, Raghuvir Singh

2016-06-01

The proteolytic clipping of histone tails has recently emerged as a novel form of irreversible post-translational modification (PTM) of histones. Histone clipping has been implicated as a regulatory process leading to the permanent removal of PTMs from histone proteins. However, there is scarcity of literature that describes the identification and characterization of histone-specific proteases. Here, we employed various biochemical methods to report histone H3-specific proteolytic activity from budding yeast. Our results demonstrate that H3 proteolytic activity was associated with sepharose bead matrices and activity was not affected by a variety of stress conditions. We have also identified the existence of an unknown protein that acts as a physiological inhibitor of the H3-clipping activity of yeast H3 protease. Moreover, through protease inhibition assays, we have also characterized yeast H3 protease as a serine protease. Interestingly, unlike glutamate dehydrogenase (GDH), yeast H3 proteolytic activity was not inhibited by Stefin B. Together, our findings suggest the existence of a novel H3 protease in yeast that is different from other reported histone H3 proteases. The presence of histone H3 proteolytic activity, along with the physiological inhibitor in yeast, suggests an interesting molecular mechanism that regulates the activity of histone proteases. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.
Male Yeast Infection: How Can I Tell if I Have One?

MedlinePlus

... tell if I have one? Can men get yeast infections? What are the signs and symptoms of a male yeast infection? Answers from James M. Steckelberg, M.D. Yes, men can get yeast infections, too, which can lead to a condition ...
Indole-3-Acetic Acid-Producing Yeasts in the Phyllosphere of the Carnivorous Plant Drosera indica L

PubMed Central

Shin, Li-Ying; Wei, Jyuan-Yu; Fu, Shih-Feng; Chou, Jui-Yu

2014-01-01

Yeasts are widely distributed in nature and exist in association with other microorganisms as normal inhabitants of soil, vegetation, and aqueous environments. In this study, 12 yeast strains were enriched and isolated from leaf samples of the carnivorous plant Drosera indica L., which is currently threatened because of restricted habitats and use in herbal industries. According to similarities in large subunit and small subunit ribosomal RNA gene sequences, we identified 2 yeast species in 2 genera of the phylum Ascomycota, and 5 yeast species in 5 genera of the phylum Basidiomycota. All of the isolated yeasts produced indole-3-acetic acid (IAA) when cultivated in YPD broth supplemented with 0.1% L-tryptophan. Growth conditions, such as the pH and temperature of the medium, influenced yeast IAA production. Our results also suggested the existence of a tryptophan-independent IAA biosynthetic pathway. We evaluated the effects of various concentrations of exogenous IAA on yeast growth and observed that IAA produced by wild yeasts modifies auxin-inducible gene expression in Arabidopsis. Our data suggest that yeasts can promote plant growth and support ongoing prospecting of yeast strains for inclusion into biofertilizer for sustainable agriculture. PMID:25464336
Effects of yeast stress and pH on 3-monochloropropanediol (3-MCPD)-producing reactions in model dough systems.

PubMed

Hamlet, C G; Sadd, P A

2005-07-01

A major precursor of 3-monochloropropanediol (3-MCPD) in leavened cereal products is glycerol, which is formed as a natural by-product of yeast fermentation. However, yeast metabolism is affected by stresses such as low osmotic pressure from, for example, the incorporation of sugar or salt in the dough recipe. Tests with model doughs have shown that glycerol production was proportional to yeast mass and limited by available sugars, but that high levels of yeast inhibited 3-MCPD formation. The yeast fraction responsible for the inhibition of 3-MCPD in model dough was shown to be the soluble cytosol proteins, and the inhibition mechanism could be explained by the known reactions of 3-MCPD and/or its precursors with ammonia/amino acids (from yeast proteins). Added glucose did not increase the production of glycerol by yeast but it did promote the generation of 3-MCPD in cooked doughs. The latter effect was attributed to the removal of 3-MCPD inhibitors such as ammonia and amino acids by their reactions with added glucose (e.g. Maillard). The thermal generation of organic acids from added glucose also reduced the pH of cooked doughs, so the effect of pH and short-chain organic acids on 3-MCPD generation in dough was measured. There was a good correlation between initial dough pH and the level of 3-MCPD generated. The effect was weaker than that predicted by simple kinetic modelling, suggesting that the involvement of H+ and/or the organic acid was catalytic. The results showed that modifications to dough recipes involving the addition of reducing sugars and/or organic acids can have a significant impact on 3-MPCD generation in bakery products.
Structure of the Get3 targeting factor in complex with its membrane protein cargo

DOE PAGES

Mateja, Agnieszka; Paduch, Marcin; Chang, Hsin-Yang; ...

2015-03-06

Tail-anchored (TA) proteins are a physiologically important class of membrane proteins targeted to the endoplasmic reticulum by the conserved guided-entry of TA proteins (GET) pathway. During transit, their hydrophobic transmembrane domains (TMDs) are chaperoned by the cytosolic targeting factor Get3, but the molecular nature of the functional Get3-TA protein targeting complex remains unknown. In this paper, we reconstituted the physiologic assembly pathway for a functional targeting complex and showed that it comprises a TA protein bound to a Get3 homodimer. Crystal structures of Get3 bound to different TA proteins showed an α-helical TMD occupying a hydrophobic groove that spans themore » Get3 homodimer. Finally, our data elucidate the mechanism of TA protein recognition and shielding by Get3 and suggest general principles of hydrophobic domain chaperoning by cellular targeting factors.« less
Interaction surface and topology of Get3-Get4-Get5 protein complex, involved in targeting tail-anchored proteins to endoplasmic reticulum.

PubMed

Chang, Yi-Wei; Lin, Tai-Wen; Li, Yi-Chuan; Huang, Yu-Shan; Sun, Yuh-Ju; Hsiao, Chwan-Deng

2012-02-10

Recent work has uncovered the "GET system," which is responsible for endoplasmic reticulum targeting of tail-anchored proteins. Although structural information and the individual roles of most components of this system have been defined, the interactions and interplay between them remain to be elucidated. Here, we investigated the interactions between Get3 and the Get4-Get5 complex from Saccharomyces cerevisiae. We show that Get3 interacts with Get4-Get5 via an interface dominated by electrostatic forces. Using isothermal titration calorimetry and small-angle x-ray scattering, we further demonstrate that the Get3 homodimer interacts with two copies of the Get4-Get5 complex to form an extended conformation in solution.
Molecular partners of hNOT/ALG3, the human counterpart of the Drosophila NOT and yeast ALG3 gene, suggest its involvement in distinct cellular processes relevant to congenital disorders of glycosylation, cancer, neurodegeneration and a variety of further pathologies.

PubMed

Hacker, Benedikt; Schultheiß, Christoph; Döring, Michael; Kurzik-Dumke, Ursula

2018-06-01

This study provides first insights into the involvement of hNOT/ALG3, the human counterpart of the Drosophila Neighbour of TID and yeast ALG3 gene, in various putative molecular networks. HNOT/ALG3 encodes two translated transcripts encoding precursor proteins differing in their N-terminus and showing 33% identity with the yeast asparagine-linked glycosylation 3 (ALG3) protein. Experimental evidence for the functional homology of the proteins of fly and man in the N-glycosylation has still to be provided. In this study, using the yeast two-hybrid technique we identify 17 molecular partners of hNOT-1/ALG3-1. We disclose the building of hNOT/ALG3 homodimers and provide experimental evidence for its in vivo interaction with the functionally linked proteins OSBP, OSBPL9 and LRP1, the SYPL1 protein and the transcription factor CREB3. Regarding the latter, we show that the 55 kDa N-glycosylated hNOT-1/ALG3-1 molecule binds the N-glycosylated CREB3 precursor but does not interact with CREB3's proteolytic products specific to the endoplasmic reticulum and to the nucleus. The interaction between the two partners is a prerequisite for the proteolytic activation of CREB3. In case of the further binding partners, our data suggest that hNOT-1/ALG3-1 interacts with both OSBPs and with their direct targets LRP1 and VAMP/VAP-A. Moreover, our results show that various partners of hNOT-1/ALG3-1 interact with its diverse post translationally processed products destined to distinct cellular compartments. Generally, our data suggest the involvement of hNOT-1/ALG3-1 in various molecular contexts determining essential processes associated with distinct cellular machineries and related to various pathologies, such as cancer, viral infections, neuronal and immunological disorders and CDG.
The structure of a β-(1→3)-d-glucan from yeast cell walls

PubMed Central

Manners, David J.; Masson, Alan J.; Patterson, James C.

1973-01-01

Yeast glucan as normally prepared by various treatments of yeast (Saccharomyces cerevisiae) cell walls to remove mannan and glycogen is still heterogeneous. The major component (about 85%) is a branched β-(1→3)-glucan of high molecular weight (about 240000) containing 3% of β-(1→6)-glucosidic interchain linkages. The minor component is a branched β-(1→6)-glucan. A comparison of our results with those of other workers suggests that different glucan preparations may differ in the degree of heterogeneity and that the major β-(1→3)-glucan component may vary considerably in degree of branching. PMID:4359920
Get3 is a holdase chaperone and moves to deposition sites for aggregated proteins when membrane targeting is blocked

PubMed Central

Powis, Katie; Schrul, Bianca; Tienson, Heather; Gostimskaya, Irina; Breker, Michal; High, Stephen; Schuldiner, Maya; Jakob, Ursula; Schwappach, Blanche

2013-01-01

Summary The endomembrane system of yeast contains different tail-anchored proteins that are post-translationally targeted to membranes via their C-terminal transmembrane domain. This hydrophobic segment could be hazardous in the cytosol if membrane insertion fails, resulting in the need for energy-dependent chaperoning and the degradation of aggregated tail-anchored proteins. A cascade of GET proteins cooperates in a conserved pathway to accept newly synthesized tail-anchored proteins from ribosomes and guide them to a receptor at the endoplasmic reticulum, where membrane integration takes place. It is, however, unclear how the GET system reacts to conditions of energy depletion that might prevent membrane insertion and hence lead to the accumulation of hydrophobic proteins in the cytosol. Here we show that the ATPase Get3, which accommodates the hydrophobic tail anchor of clients, has a dual function: promoting tail-anchored protein insertion when glucose is abundant and serving as an ATP-independent holdase chaperone during energy depletion. Like the generic chaperones Hsp42, Ssa2, Sis1 and Hsp104, we found that Get3 moves reversibly to deposition sites for protein aggregates, hence supporting the sequestration of tail-anchored proteins under conditions that prevent tail-anchored protein insertion. Our findings support a ubiquitous role for the cytosolic GET complex as a triaging platform involved in cellular proteostasis. PMID:23203805
Boric acid-dependent decrease in regulatory histone H3 acetylation is not mutagenic in yeast.

PubMed

Pointer, Benjamin R; Schmidt, Martin

2016-07-01

Candida albicans is a dimorphic yeast commonly found on human mucosal membranes that switches from yeast to hyphal morphology in response to environmental factors. The change to hyphal growth requires histone H3 modifications by the yeast-specific histone acetyltransferase Rtt109. In addition to its role in morphogenesis, Rtt109-dependent acetylation of histone H3 lysine residues 9 and 56 has regulatory functions during DNA replication and repair. Boric acid (BA) is a broad-spectrum agent that specifically inhibits C. albicans hyphal growth, locking the fungus in its harmless commensal yeast state. The present study characterizes the effect of BA on C. albicans histone acetylation in respect to specificity, time-course and significance. We demonstrate that sublethal concentrations of BA reduce H3K9/H3K56 acetylation, both on a basal level and in response to genotoxic stress. Acetylation at other selected histone sites were not affected by BA. qRT-PCR expression analysis of the DNA repair gene Rad51 indicated no elevated level of genotoxic stress during BA exposure. A forward-mutation analysis demonstrated the BA does not increase spontaneous or induced mutations. The findings suggest that DNA repair remains effective even when histone H3 acetylation decreases and dispels the notion that BA treatment impairs genome integrity in yeast. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Six-coordinate manganese(3+) in catalysis by yeast manganese superoxide dismutase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheng, Yuewei; Gralla, Edith Butler; Schumacher, Mikhail

Reduction of superoxide (O{sub 2}{sup -}) by manganese-containing superoxide dismutase occurs through either a 'prompt protonation' pathway, or an 'inner-sphere' pathway, with the latter leading to formation of an observable Mn-peroxo complex. We recently reported that wild-type (WT) manganese superoxide dismutases (MnSODs) from Saccharomyces cerevisiae and Candida albicans are more gated toward the 'prompt protonation' pathway than human and bacterial MnSODs and suggested that this could result from small structural changes in the second coordination sphere of manganese. We report here that substitution of a second-sphere residue, Tyr34, by phenylalanine (Y34F) causes the MnSOD from S. cerevisiae to react exclusivelymore » through the 'inner-sphere' pathway. At neutral pH, we have a surprising observation that protonation of the Mn-peroxo complex in the mutant yeast enzyme occurs through a fast pathway, leading to a putative six-coordinate Mn3+ species, which actively oxidizes O{sub 2}{sup -} in the catalytic cycle. Upon increasing pH, the fast pathway is gradually replaced by a slow proton-transfer pathway, leading to the well-characterized five-coordinate Mn{sup 3+}. We here propose and compare two hypothetical mechanisms for the mutant yeast enzyme, diffeeing in the structure of the Mn-peroxo complex yet both involving formation of the active six-coordinate Mn{sup 3+} and proton transfer from a second-sphere water molecule, which has substituted for the -OH of Tyr34, to the Mn-peroxo complex. Because WT and the mutant yeast MnSOD both rest in the 2+ state and become six-coordinate when oxidized up from Mn{sup 2+}, six-coordinate Mn{sup 3+} species could also actively function in the mechanism of WT yeast MnSODs.« less
Structural analysis of the core COMPASS family of histone H3K4 methylases from yeast to human

PubMed Central

Takahashi, Yoh-hei; Westfield, Gerwin H.; Oleskie, Austin N.; Trievel, Raymond C.; Shilatifard, Ali; Skiniotis, Georgios

2011-01-01

Histone H3 lysine 4 (H3K4) methylation is catalyzed by the highly evolutionarily conserved multiprotein complex known as Set1/COMPASS or MLL/COMPASS-like complexes from yeast to human, respectively. Here we have reconstituted fully functional yeast Set1/COMPASS and human MLL/COMPASS-like complex in vitro and have identified the minimum subunit composition required for histone H3K4 methylation. These subunits include the methyltransferase C-terminal SET domain of Set1/MLL, Cps60/Ash2L, Cps50/RbBP5, Cps30/WDR5, and Cps25/Dpy30, which are all common components of the COMPASS family from yeast to human. Three-dimensional (3D) cryo-EM reconstructions of the core yeast complex, combined with immunolabeling and two-dimensional (2D) EM analysis of the individual subcomplexes reveal a Y-shaped architecture with Cps50 and Cps30 localizing on the top two adjacent lobes and Cps60-Cps25 forming the base at the bottom. EM analysis of the human complex reveals a striking similarity to its yeast counterpart, suggesting a common subunit organization. The SET domain of Set1 is located at the juncture of Cps50, Cps30, and the Cps60-Cps25 module, lining the walls of a central channel that may act as the platform for catalysis and regulative processing of various degrees of H3K4 methylation. This structural arrangement suggested that COMPASS family members function as exo-methylases, which we have confirmed by in vitro and in vivo studies. PMID:22158900
Structural analysis of the core COMPASS family of histone H3K4 methylases from yeast to human.

PubMed

Takahashi, Yoh-hei; Westfield, Gerwin H; Oleskie, Austin N; Trievel, Raymond C; Shilatifard, Ali; Skiniotis, Georgios

2011-12-20

Histone H3 lysine 4 (H3K4) methylation is catalyzed by the highly evolutionarily conserved multiprotein complex known as Set1/COMPASS or MLL/COMPASS-like complexes from yeast to human, respectively. Here we have reconstituted fully functional yeast Set1/COMPASS and human MLL/COMPASS-like complex in vitro and have identified the minimum subunit composition required for histone H3K4 methylation. These subunits include the methyltransferase C-terminal SET domain of Set1/MLL, Cps60/Ash2L, Cps50/RbBP5, Cps30/WDR5, and Cps25/Dpy30, which are all common components of the COMPASS family from yeast to human. Three-dimensional (3D) cryo-EM reconstructions of the core yeast complex, combined with immunolabeling and two-dimensional (2D) EM analysis of the individual subcomplexes reveal a Y-shaped architecture with Cps50 and Cps30 localizing on the top two adjacent lobes and Cps60-Cps25 forming the base at the bottom. EM analysis of the human complex reveals a striking similarity to its yeast counterpart, suggesting a common subunit organization. The SET domain of Set1 is located at the juncture of Cps50, Cps30, and the Cps60-Cps25 module, lining the walls of a central channel that may act as the platform for catalysis and regulative processing of various degrees of H3K4 methylation. This structural arrangement suggested that COMPASS family members function as exo-methylases, which we have confirmed by in vitro and in vivo studies.
Identification of Yju3p as functional orthologue of mammalian monoglyceride lipase in the yeast Saccharomycescerevisiae.

PubMed

Heier, Christoph; Taschler, Ulrike; Rengachari, Srinivasan; Oberer, Monika; Wolinski, Heimo; Natter, Klaus; Kohlwein, Sepp D; Leber, Regina; Zimmermann, Robert

2010-09-01

Monoacylglycerols (MAGs) are short-lived intermediates of glycerolipid metabolism. Specific molecular species, such as 2-arachidonoylglycerol, which is a potent activator of cannabinoid receptors, may also function as lipid signaling molecules. In mammals, enzymes hydrolyzing MAG to glycerol and fatty acids, resembling the final step in lipolysis, or esterifying MAG to diacylglycerol, are well known; however, despite the high level of conservation of lipolysis, the corresponding activities in yeast have not been characterized yet. Here we provide evidence that the protein Yju3p functions as a potent MAG hydrolase in yeast. Cellular MAG hydrolase activity was decreased by more than 90% in extracts of Yju3p-deficient cells, indicating that Yju3p accounts for the vast majority of this activity in yeast. Loss of this activity was restored by heterologous expression of murine monoglyceride lipase (MGL). Since yju3Delta mutants accumulated MAG in vivo only at very low concentrations, we considered the possibility that MAGs are re-esterified into DAG by acyltransferases. Indeed, cellular MAG levels were further increased in mutant cells lacking Yju3p and Dga1p or Lro1p acyltransferase activities. In conclusion, our studies suggest that catabolic and anabolic reactions affect cellular MAG levels. Yju3p is the functional orthologue of mammalian MGL and is required for efficient degradation of MAG in yeast. 2010 Elsevier B.V. All rights reserved.
Identification of Yju3p as functional orthologue of mammalian monoglyceride lipase in the yeast Saccharomycescerevisiae

PubMed Central

Heier, Christoph; Taschler, Ulrike; Rengachari, Srinivasan; Oberer, Monika; Wolinski, Heimo; Natter, Klaus; Kohlwein, Sepp D.; Leber, Regina; Zimmermann, Robert

2010-01-01

Monoacylglycerols (MAGs) are short-lived intermediates of glycerolipid metabolism. Specific molecular species, such as 2-arachidonoylglycerol, which is a potent activator of cannabinoid receptors, may also function as lipid signaling molecules. In mammals, enzymes hydrolyzing MAG to glycerol and fatty acids, resembling the final step in lipolysis, or esterifying MAG to diacylglycerol, are well known; however, despite the high level of conservation of lipolysis, the corresponding activities in yeast have not been characterized yet. Here we provide evidence that the protein Yju3p functions as a potent MAG hydrolase in yeast. Cellular MAG hydrolase activity was decreased by more than 90% in extracts of Yju3p-deficient cells, indicating that Yju3p accounts for the vast majority of this activity in yeast. Loss of this activity was restored by heterologous expression of murine monoglyceride lipase (MGL). Since yju3Δ mutants accumulated MAG in vivo only at very low concentrations, we considered the possibility that MAGs are re-esterified into DAG by acyltransferases. Indeed, cellular MAG levels were further increased in mutant cells lacking Yju3p and Dga1p or Lro1p acyltransferase activities. In conclusion, our studies suggest that catabolic and anabolic reactions affect cellular MAG levels. Yju3p is the functional orthologue of mammalian MGL and is required for efficient degradation of MAG in yeast. PMID:20554061
An N-terminal fragment of yeast ribosomal protein L3 inhibits the cytotoxicity of pokeweed antiviral protein in Saccharomyces cerevisiae.

PubMed

Di, Rong; Tumer, Nilgun E

2014-04-11

We have previously shown that ribosomal protein L3 is required for pokeweed antiviral protein (PAP), a type I ribosome inactivating protein, to bind to ribosomes and depurinate the α-sarcin/ricin loop (SRL) in yeast. Co-expression of the N-terminal 99 amino acids of yeast L3 (L3Δ99) with PAP in transgenic tobacco plants completely abolished the toxicity of PAP. In this study, we investigated the interaction between PAP and L3Δ99 in Saccharomyces cerevisiae. Yeast cells co-transformed with PAP and L3Δ99 showed markedly reduced growth inhibition and reduced rRNA depurination by PAP, compared to cells transformed with PAP alone. Co-transformation of yeast with PAP and L3Δ21 corresponding to the highly conserved N-terminal 21 amino acids of L3Δ99, reduced the cytotoxicity of PAP. PAP mRNA and protein levels were elevated and L3Δ99 or L3Δ21 mRNA and protein levels were reduced in yeast co-transformed with PAP and L3Δ99 or with PAP and L3Δ21, respectively. PAP interacted with L3Δ21 in yeast cells in vivo and by Biacore analysis in vitro, suggesting that the interaction between L3Δ21 and PAP may inhibit PAP-mediated depurination of the SRL, leading to a reduction in the cytotoxicity of PAP.
Transport and cytotoxicity of the anticancer drug 3-bromopyruvate in the yeast Saccharomyces cerevisiae.

PubMed

Lis, Paweł; Zarzycki, Marek; Ko, Young H; Casal, Margarida; Pedersen, Peter L; Goffeau, Andre; Ułaszewski, Stanisław

2012-02-01

We have investigated the cytotoxicity in Saccharomyces cerevisiae of the novel antitumor agent 3-bromopyruvate (3-BP). 3-BP enters the yeast cells through the lactate/pyruvate H(+) symporter Jen1p and inhibits cell growth at minimal inhibitory concentration of 1.8 mM when grown on non-glucose conditions. It is not submitted to the efflux pumps conferring Pleiotropic Drug Resistance in yeast. Yeast growth is more sensitive to 3-BP than Gleevec (Imatinib methanesulfonate) which in contrast to 3-BP is submitted to the PDR network of efflux pumps. The sensitivity of yeast to 3-BP is increased considerably by mutations or chemical treatment by buthionine sulfoximine that decrease the intracellular concentration of glutathione.
Cell cycle- and chaperone-mediated regulation of H3K56ac incorporation in yeast.

PubMed

Kaplan, Tommy; Liu, Chih Long; Erkmann, Judith A; Holik, John; Grunstein, Michael; Kaufman, Paul D; Friedman, Nir; Rando, Oliver J

2008-11-01

Acetylation of histone H3 lysine 56 is a covalent modification best known as a mark of newly replicated chromatin, but it has also been linked to replication-independent histone replacement. Here, we measured H3K56ac levels at single-nucleosome resolution in asynchronously growing yeast cultures, as well as in yeast proceeding synchronously through the cell cycle. We developed a quantitative model of H3K56ac kinetics, which shows that H3K56ac is largely explained by the genomic replication timing and the turnover rate of each nucleosome, suggesting that cell cycle profiles of H3K56ac should reveal most first-time nucleosome incorporation events. However, since the deacetylases Hst3/4 prevent use of H3K56ac as a marker for histone deposition during M phase, we also directly measured M phase histone replacement rates. We report a global decrease in turnover rates during M phase and a further specific decrease in turnover at several early origins of replication, which switch from rapidly replaced in G1 phase to stably bound during M phase. Finally, by measuring H3 replacement in yeast deleted for the H3K56 acetyltransferase Rtt109 and its two co-chaperones Asf1 and Vps75, we find evidence that Rtt109 and Asf1 preferentially enhance histone replacement at rapidly replaced nucleosomes, whereas Vps75 appears to inhibit histone turnover at those loci. These results provide a broad perspective on histone replacement/incorporation throughout the cell cycle and suggest that H3K56 acetylation provides a positive-feedback loop by which replacement of a nucleosome enhances subsequent replacement at the same location.

Genome-wide bisulfite sensitivity profiling of yeast suggests bisulfite inhibits transcription.

PubMed

Segovia, Romulo; Mathew, Veena; Tam, Annie S; Stirling, Peter C

2017-09-01

Bisulfite, in the form of sodium bisulfite or metabisulfite, is used commercially as a food preservative. Bisulfite is used in the laboratory as a single-stranded DNA mutagen in epigenomic analyses of DNA methylation. Recently it has also been used on whole yeast cells to induce mutations in exposed single-stranded regions in vivo. To understand the effects of bisulfite on live cells we conducted a genome-wide screen for bisulfite sensitive mutants in yeast. Screening the deletion mutant array, and collections of essential gene mutants we define a genetic network of bisulfite sensitive mutants. Validation of screen hits revealed hyper-sensitivity of transcription and RNA processing mutants, rather than DNA repair pathways and follow-up analyses support a role in perturbation of RNA transactions. We propose a model in which bisulfite-modified nucleotides may interfere with transcription or RNA metabolism when used in vivo. Copyright © 2017 Elsevier B.V. All rights reserved.
Drosophila Regulate Yeast Density and Increase Yeast Community Similarity in a Natural Substrate

PubMed Central

Stamps, Judy A.; Yang, Louie H.; Morales, Vanessa M.; Boundy-Mills, Kyria L.

2012-01-01

Drosophila melanogaster adults and larvae, but especially larvae, had profound effects on the densities and community structure of yeasts that developed in banana fruits. Pieces of fruit exposed to adult female flies previously fed fly-conditioned bananas developed higher yeast densities than pieces of the same fruits that were not exposed to flies, supporting previous suggestions that adult Drosophila vector yeasts to new substrates. However, larvae alone had dramatic effects on yeast density and species composition. When yeast densities were compared in pieces of the same fruits assigned to different treatments, fruits that developed low yeast densities in the absence of flies developed significantly higher yeast densities when exposed to larvae. Across all of the fruits, larvae regulated yeast densities within narrow limits, as compared to a much wider range of yeast densities that developed in pieces of the same fruits not exposed to flies. Larvae also affected yeast species composition, dramatically reducing species diversity across fruits, reducing variation in yeast communities from one fruit to the next (beta diversity), and encouraging the consistent development of a yeast community composed of three species of yeast (Candida californica, C. zemplinina, and Pichia kluvyeri), all of which were palatable to larvae. Larvae excreted viable cells of these three yeast species in their fecal pools, and discouraged the growth of filamentous fungi, processes which may have contributed to their effects on the yeast communities in banana fruits. These and other findings suggest that D. melanogaster adults and their larval offspring together engage in ‘niche construction’, facilitating a predictable microbial environment in the fruit substrates in which the larvae live and develop. PMID:22860093
A Comparison of the Beneficial Effects of Live and Heat-Inactivated Baker's Yeast on Nile Tilapia: Suggestions on the Role and Function of the Secretory Metabolites Released from the Yeast.

PubMed

Ran, Chao; Huang, Lu; Liu, Zhi; Xu, Li; Yang, Yalin; Tacon, Philippe; Auclair, Eric; Zhou, Zhigang

2015-01-01

Yeast is frequently used as a probiotic in aquaculture with the potential to substitute for antibiotics. In this study, the involvement and extent to which the viability of yeast cells and thus the secretory metabolites released from the yeast contribute to effects of baker's yeast was investigated in Nile tilapia. No yeast, live yeast or heat-inactivated baker's yeast were added to basal diets high in fishmeal and low in soybean (diet A) or low in fishmeal and high in soybean (diet B), which were fed to fish for 8 weeks. Growth, feed utilization, gut microvilli morphology, and expressions of hsp70 and inflammation-related cytokines in the intestine and head kidney were assessed. Intestinal microbiota was investigated using 16S rRNA gene pyrosequencing. Gut alkaline phosphatase (AKP) activity was measured after challenging the fish with Aeromonas hydrophila. Results showed that live yeast significantly improved FBW and WG (P < 0.05), and tended to improve FCR (P = 0.06) of fish compared to the control (no yeast). No significant differences were observed between inactivated yeast and control. Live yeast improved gut microvilli length (P < 0.001) and density (P < 0.05) while inactivated yeast did not. The hsp70 expression level in both the intestine and head kidney of fish was significantly reduced by live yeast (P < 0.05) but not inactivated yeast. Live yeast but not inactivated yeast reduced intestinal expression of tnfα (P < 0.05), tgfβ (P < 0.05 under diet A) and il1β (P = 0.08). Intestinal Lactococcus spp. numbers were enriched by both live and inactivated yeast. Lastly, both live and inactivated yeast reduced the gut AKP activity compared to the control (P < 0.001), indicating protection of the host against infection by A. hydrophila. In conclusion, secretory metabolites did not play major roles in the growth promotion and disease protection effects of yeast. Nevertheless, secretory metabolites were the major contributing factor towards improved gut
Digestion of Yeasts and Beta-1,3-Glucanases in Mosquito Larvae: Physiological and Biochemical Considerations.

PubMed

Souza, Raquel Santos; Diaz-Albiter, Hector Manuel; Dillon, Vivian Maureen; Dillon, Rod J; Genta, Fernando Ariel

2016-01-01

Aedes aegypti larvae ingest several kinds of microorganisms. In spite of studies regarding mosquito digestion, little is known about the nutritional utilization of ingested cells by larvae. We investigated the effects of using yeasts as the sole nutrient source for A. aegypti larvae. We also assessed the role of beta-1,3-glucanases in digestion of live yeast cells. Beta-1,3-glucanases are enzymes which hydrolyze the cell wall beta-1,3-glucan polyssacharide. Larvae were fed with cat food (controls), live or autoclaved Saccharomyces cerevisiae cells and larval weight, time for pupation and adult emergence, larval and pupal mortality were measured. The presence of S. cerevisiae cells inside the larval gut was demonstrated by light microscopy. Beta-1,3-glucanase was measured in dissected larval samples. Viability assays were performed with live yeast cells and larval gut homogenates, with or without addition of competing beta-1,3-glucan. A. aegypti larvae fed with yeast cells were heavier at the 4th instar and showed complete development with normal mortality rates. Yeast cells were efficiently ingested by larvae and quickly killed (10% death in 2 h, 100% in 48 h). Larvae showed beta-1,3-glucanase in head, gut and rest of body. Gut beta-1,3-glucanase was not derived from ingested yeast cells. Gut and rest of body activity was not affected by the yeast diet, but head homogenates showed a lower activity in animals fed with autoclaved S. cerevisiae cells. The enzymatic lysis of live S. cerevisiae cells was demonstrated using gut homogenates, and this activity was abolished when excess beta-1,3-glucan was added to assays. These results show that live yeast cells are efficiently ingested and hydrolyzed by A. aegypti larvae, which are able to fully-develop on a diet based exclusively on these organisms. Beta-1,3-glucanase seems to be essential for yeast lytic activity of A. aegypti larvae, which possess significant amounts of these enzyme in all parts investigated.
Heterologous expression of anti-apoptotic human 14-3-3β/α enhances iron-mediated programmed cell death in yeast

PubMed Central

Eid, Rawan; Zhou, David R.; Arab, Nagla T. T.; Boucher, Eric; Young, Paul G.; Mandato, Craig A.

2017-01-01

The induction of Programmed Cell Death (PCD) requires the activation of complex responses involving the interplay of a variety of different cellular proteins, pathways, and processes. Uncovering the mechanisms regulating PCD requires an understanding of the different processes that both positively and negatively regulate cell death. Here we have examined the response of normal as well as PCD resistant yeast cells to different PCD inducing stresses. As expected cells expressing the pro-survival human 14-3-3β/α sequence show increased resistance to numerous stresses including copper and rapamycin. In contrast, other stresses including iron were more lethal in PCD resistant 14-3-3β/α expressing cells. The increased sensitivity to PCD was not iron and 14-3-3β/α specific since it was also observed with other stresses (hydroxyurea and zinc) and other pro-survival sequences (human TC-1 and H-ferritin). Although microscopical examination revealed little differences in morphology with iron or copper stresses, cells undergoing PCD in response to high levels of prolonged copper treatment were reduced in size. This supports the interaction some forms of PCD have with the mechanisms regulating cell growth. Analysis of iron-mediated effects in yeast mutant strains lacking key regulators suggests that a functional vacuole is required to mediate the synergistic effects of iron and 14-3-3β/α on yeast PCD. Finally, mild sub-lethal levels of copper were found to attenuate the observed inhibitory effects of iron. Taken together, we propose a model in which a subset of stresses like iron induces a complex process that requires the cross-talk of two different PCD inducing pathways. PMID:28854230
Klebsiella pneumoniae type 3 fimbriae agglutinate yeast in a mannose-resistant manner.

PubMed

Stahlhut, Steen G; Struve, Carsten; Krogfelt, Karen A

2012-03-01

The ability of bacterial pathogens to express different fimbrial adhesins plays a significant role in virulence. Thus, specific detection of fimbrial expression is an important task in virulence characterization and epidemiological studies. Most clinical Klebsiella pneumoniae isolates express type 1 and type 3 fimbriae, which are characterized by mediation of mannose-sensitive agglutination of yeast cells and agglutination of tannic acid-treated ox red blood cells (RBCs), respectively. It has been observed that K. pneumoniae isolates agglutinate yeast cells and commercially available sheep RBCs in a mannose-resistant manner. Thus, this study was initiated to identify the adhesin involved. Screening of a mutant library surprisingly revealed that the mannose-resistant agglutination of yeast and sheep RBCs was mediated by type 3 fimbriae. Specific detection of type 1 fimbriae expression in K. pneumoniae was feasible only by the use of guinea pig RBCs. This was further verified by the use of isogenic fimbriae mutants and by cloning and expressing K. pneumoniae fimbrial gene clusters in Escherichia coli. Yeast agglutination assays are commonly used to detect type 1 fimbriae expression but should not be used for bacterial species able to express type 3 fimbriae. For these species, the use of guinea pig blood for specific type 1 fimbriae detection is essential. The use of commercially available sheep RBCs or yeast is an easy alternative to traditional methods to detect type 3 fimbriae expression. Easy and specific detection of expression of type 1 and type 3 fimbriae is essential in the continuous characterization of these important adhesive virulence factors present in members of the Enterobacteriaceae.
The primary structures of two yeast enolase genes. Homology between the 5' noncoding flanking regions of yeast enolase and glyceraldehyde-3-phosphate dehydrogenase genes.

PubMed

Holland, M J; Holland, J P; Thill, G P; Jackson, K A

1981-02-10

Segments of yeast genomic DNA containing two enolase structural genes have been isolated by subculture cloning procedures using a cDNA hybridization probe synthesized from purified yeast enolase mRNA. Based on restriction endonuclease and transcriptional maps of these two segments of yeast DNA, each hybrid plasmid contains a region of extensive nucleotide sequence homology which forms hybrids with the cDNA probe. The DNA sequences which flank this homologous region in the two hybrid plasmids are nonhomologous indicating that these sequences are nontandemly repeated in the yeast genome. The complete nucleotide sequence of the coding as well as the flanking noncoding regions of these genes has been determined. The amino acid sequence predicted from one reading frame of both structural genes is extremely similar to that determined for yeast enolase (Chin, C. C. Q., Brewer, J. M., Eckard, E., and Wold, F. (1981) J. Biol. Chem. 256, 1370-1376), confirming that these isolated structural genes encode yeast enolase. The nucleotide sequences of the coding regions of the genes are approximately 95% homologous, and neither gene contains an intervening sequence. Codon utilization in the enolase genes follows the same biased pattern previously described for two yeast glyceraldehyde-3-phosphate dehydrogenase structural genes (Holland, J. P., and Holland, M. J. (1980) J. Biol. Chem. 255, 2596-2605). DNA blotting analysis confirmed that the isolated segments of yeast DNA are colinear with yeast genomic DNA and that there are two nontandemly repeated enolase genes per haploid yeast genome. The noncoding portions of the two enolase genes adjacent to the initiation and termination codons are approximately 70% homologous and contain sequences thought to be involved in the synthesis and processing messenger RNA. Finally there are regions of extensive homology between the two enolase structural genes and two yeast glyceraldehyde-3-phosphate dehydrogenase structural genes within the 5
[Expression of the Drosophila melanogaster limk1 gene 3'-UTRs mRNA in Yeast Saccharomyces cerevisiae].

PubMed

Rumyantsev, A M; Zakharov, G A; Zhuravlev, A V; Padkina, M V; Savvateeva-Popova, E V; Sambuk, E V

2014-06-01

The stability of mRNA and its translation efficacy in higher eukaryotes are influenced by the interaction of 3'-untranscribed regions (3'-UTRs) with microRNAs and RNA-binding proteins. Since Saccharomyces cerevisiae lack microRNAs, it is possible to evaluate the contribution of only 3'-UTRs' and RNA-binding proteins' interaction in post-transcriptional regulation. For this, the post-transcriptional regulation of Drosophila limk1 gene encoding for the key enzyme of actin remodeling was studied in yeast. Analysis of limkl mRNA 3'-UTRs revealed the potential sites of yeast transcriptional termination. Computer remodeling demonstrated the possibility of secondary structure formation in limkl mRNA 3'-UTRs. For an evaluation of the functional activity of Drosophila 3'-UTRs in yeast, the reporter gene PHO5 encoding for yeast acid phosphatase (AP) fused to different variants of Drosophila limk1 mRNA 3'-UTRs (513, 1075, 1554 bp) was used. Assessments of AP activity and RT-PCR demonstrated that Drosophila limkl gene 3'-UTRs were functionally active and recognized in yeast. Therefore, yeast might be used as an appropriate model system for studies of 3'-UTR's role in post-transcriptional regulation.
Fission yeast translation initiation factor 3 subunit eIF3h is not essential for global translation initiation, but deletion of eif3h+ affects spore formation.

PubMed

Ray, Anirban; Bandyopadhyay, Amitabha; Matsumoto, Tomohiro; Deng, Haiteng; Maitra, Umadas

2008-11-01

The fission yeast Schizosaccharomyces pombe homologue of the p40/eIF3h subunit of mammalian translation initiation factor eIF3 has been characterized in this study. We show that this protein physically associates with the 40S ribosomal particles as a constituent of the multimeric eIF3 protein complex, which consists of all five known eIF3 core subunits (eIF3a, eIF3b, eIF3c, eIF3g and eIF3i) as well as the five non-core subunits (eIF3d, eIF3e, eIF3f, eIF3h and eIF3m) that constitute an eIF3 holocomplex in fission yeast. However, affinity purification of eIF3 from fission yeast cells expressing TAP-tagged eIF3h suggests the presence of distinct forms of eIF3 that differ in their composition of the non-core subunits. Further characterization of eIF3h shows that strains lacking eif3h(+) (eif3hDelta) are viable and show no gross defects, either in vegetative growth or in the rate of in vivo protein synthesis. Polysome profile analysis shows no apparent defects in translation initiation. Furthermore, deletion of eif3h(+) does not affect the ability of the other eIF3 subunits to remain associated with one another in a tight protein complex similar to the situation in wild-type cells. Additionally, we show that human eIF3h can functionally substitute fission yeast eIF3h in complementing in vivo a genetic deletion of eif3h(+). Interestingly, mutant eif3hDelta cells show several prominent phenotypic properties. They are hypersensitive to caffeine and highly defective in meiosis, producing either no spores or incomplete tetrads with a very high frequency. The implications of these results in relation to the functions of eIF3h in Sz. pombe are discussed. (c) 2008 John Wiley & Sons, Ltd.
A Comparison of the Beneficial Effects of Live and Heat-Inactivated Baker’s Yeast on Nile Tilapia: Suggestions on the Role and Function of the Secretory Metabolites Released from the Yeast

PubMed Central

Liu, Zhi; Xu, Li; Yang, Yalin; Tacon, Philippe; Auclair, Eric; Zhou, Zhigang

2015-01-01

Yeast is frequently used as a probiotic in aquaculture with the potential to substitute for antibiotics. In this study, the involvement and extent to which the viability of yeast cells and thus the secretory metabolites released from the yeast contribute to effects of baker’s yeast was investigated in Nile tilapia. No yeast, live yeast or heat-inactivated baker’s yeast were added to basal diets high in fishmeal and low in soybean (diet A) or low in fishmeal and high in soybean (diet B), which were fed to fish for 8 weeks. Growth, feed utilization, gut microvilli morphology, and expressions of hsp70 and inflammation-related cytokines in the intestine and head kidney were assessed. Intestinal microbiota was investigated using 16S rRNA gene pyrosequencing. Gut alkaline phosphatase (AKP) activity was measured after challenging the fish with Aeromonas hydrophila. Results showed that live yeast significantly improved FBW and WG (P < 0.05), and tended to improve FCR (P = 0.06) of fish compared to the control (no yeast). No significant differences were observed between inactivated yeast and control. Live yeast improved gut microvilli length (P < 0.001) and density (P < 0.05) while inactivated yeast did not. The hsp70 expression level in both the intestine and head kidney of fish was significantly reduced by live yeast (P < 0.05) but not inactivated yeast. Live yeast but not inactivated yeast reduced intestinal expression of tnfα (P < 0.05), tgfβ (P < 0.05 under diet A) and il1β (P = 0.08). Intestinal Lactococcus spp. numbers were enriched by both live and inactivated yeast. Lastly, both live and inactivated yeast reduced the gut AKP activity compared to the control (P < 0.001), indicating protection of the host against infection by A. hydrophila. In conclusion, secretory metabolites did not play major roles in the growth promotion and disease protection effects of yeast. Nevertheless, secretory metabolites were the major contributing factor towards improved gut
Acetylated Histone H3K9 is associated with meiotic recombination hotspots, and plays a role in recombination redundantly with other factors including the H3K4 methylase Set1 in fission yeast

PubMed Central

Yamada, Shintaro; Ohta, Kunihiro; Yamada, Takatomi

2013-01-01

Histone modifications are associated with meiotic recombination hotspots, discrete sites with augmented recombination frequency. For example, trimethylation of histone H3 lysine4 (H3K4me3) marks most hotspots in budding yeast and mouse. Modified histones are known to regulate meiotic recombination partly by promoting DNA double-strand break (DSB) formation at hotspots, but the role and precise landscape of involved modifications remain unclear. Here, we studied hotspot-associated modifications in fission yeast and found general features: acetylation of H3 lysine9 (H3K9ac) is elevated, and H3K4me3 is not significantly enriched. Mutating H3K9 to non-acetylatable alanine mildly reduced levels of the DSB-inducing protein Rec12 (the fission yeast homologue of Spo11) and DSB at hotspots, indicating that H3K9ac may be involved in DSB formation by enhancing the interaction between Rec12 and hotspots. In addition, we found that the lack of the H3K4 methyltransferase Set1 generally increased Rec12 binding to chromatin but partially reduced DSB formation at some loci, suggesting that Set1 is also involved in DSB formation. These results suggest that meiotic DSB formation is redundantly regulated by multiple chromatin-related factors including H3K9ac and Set1 in fission yeast. PMID:23382177
Amyloid-like assembly of the low complexity domain of yeast Nab3.

PubMed

O'Rourke, Thomas W; Loya, Travis J; Head, PamelaSara E; Horton, John R; Reines, Daniel

2015-01-01

Termination of transcription of short non-coding RNAs is carried out in yeast by the Nab3-Nrd1-Sen1 complex. Nab3 and Nrd1 are hnRNP-like proteins that dimerize and bind RNA with sequence specificity. We show here that an essential region of Nab3 that is predicted to be prion-like based upon its sequence bias, formed amyloid-like filaments. A similar region from Nrd1 also assembled into filaments in vitro. The purified Nab3 domain formed a macroscopic gel whose lattice organization was observed by X-ray fiber diffraction. Filaments were resistant to dissociation in anionic detergent, bound the fluorescent dye thioflavin T, and showed a β-sheet rich structure by circular dichroism spectroscopy, similar to human amyloid β which served as a reference amyloid. A version of the Nab3 domain with a mutation that impairs its termination function, also formed fibers as observed by electron microscopy. Using a protein fragment interaction assay, the purified Nab3 domain was seen to interact with itself in living yeast. A similar observation was made for full length Nab3. These results suggest that the Nab3 and Nrd1 RNA-binding proteins can attain a complex polymeric form and raise the possibility that this property is important for organizing their functional state during termination. These findings are congruent with recent work showing that RNA binding proteins with low complexity domains form a dynamic subcellular matrix in which RNA metabolism takes place but can also aberrantly yield pathological aggregated particles.
Adaptive divergence in wine yeasts and their wild relatives suggests a prominent role for introgressions and rapid evolution at noncoding sites.

PubMed

Almeida, Pedro; Barbosa, Raquel; Bensasson, Douda; Gonçalves, Paula; Sampaio, José Paulo

2017-04-01

In Saccharomyces cerevisiae, the main yeast in wine fermentation, the opportunity to examine divergence at the molecular level between a domesticated lineage and its wild counterpart arose recently due to the identification of the closest relatives of wine strains, a wild population associated with Mediterranean oaks. As genomic data are available for a considerable number of representatives belonging to both groups, we used population genomics to estimate the degree and distribution of nucleotide variation between wine yeasts and their closest wild relatives. We found widespread genomewide divergence, particularly at noncoding sites, which, together with above average divergence in trans-acting DNA binding proteins, may suggest an important role for divergence at the level of transcriptional regulation. Nine outlier regions putatively under strong divergent selection were highlighted by a genomewide scan under stringent conditions. Several cases of introgressions, originating in the sibling species Saccharomyces paradoxus, were also identified in the Mediterranean oak population. FZF1 and SSU1, mostly known for conferring sulphite resistance in wine yeasts, were among the introgressed genes, although not fixed. Because the introgressions detected in our study are not found in wine strains, we hypothesize that ongoing divergent ecological selection segregates the two forms between the different niches. Together, our results provide a first insight into the extent and kind of divergence between wine yeasts and their closest wild relatives. © 2017 John Wiley & Sons Ltd.
Requirement of the yeast MSH3 and MSH6 genes for MSH2-dependent genomic stability.

PubMed

Johnson, R E; Kovvali, G K; Prakash, L; Prakash, S

1996-03-29

Defects in DNA mismatch repair result in instability of simple repetitive DNA sequences and elevated levels of spontaneous mutability. The human G/T mismatch binding protein, GTBP/p160, has been suggested to have a role in the repair of base-base and single nucleotide insertion-deletion mismatches. Here we examine the role of the yeast GTBP homolog, MSH6, in mismatch repair. We show that both MSH6 and MSH3 genes are essential for normal genomic stability. Interestingly, although mutations in either MSH3 or MSH6 do not cause the extreme microsatellite instability and spontaneous mutability observed in the msh2 mutant, yeast cells harboring null mutations in both the MSH3 and MSH6 genes exhibit microsatellite instability and mutability similar to that in the msh2 mutant. Results from epistasis analyses indicate that MSH2 functions in mismatch repair in conjunction with MSH3 or MSH6 and that MSH3 and MSH6 constitute alternate pathways of MSH2-dependent mismatch repair.
Characterization of the interaction of yeast enolase with polynucleotides.

PubMed

al-Giery, A G; Brewer, J M

1992-09-23

Yeast enolase is inhibited under certain conditions by DNA. The enzyme binds to single-stranded DNA-cellulose. Inhibition was used for routine characterization of the interaction. The presence of the substrate 2-phospho-D-glycerate reduces inhibition and binding. Both yeast enolase isozymes behave similarly. Impure yeast enolase was purified by adsorption onto a single-stranded DNA-cellulose column followed by elution with substrate. Interaction with RNA, double-stranded DNA, or degraded DNA results in less inhibition, suggesting that yeast enolase preferentially binds single-stranded DNA. However, yeast enolase is not a DNA-unwinding protein. The enzyme is inhibited by the short synthetic oligodeoxynucleotides G6, G8 and G10 but not T8 or T6, suggesting some base specificity in the interaction. The interaction is stronger at more acid pH values, with an apparent pK of 5.6. The interaction is prevented by 0.3 M KCl, suggesting that electrostatic factors are important. Histidine or lysine reverse the inhibition at lower concentrations, while phosphate is still more effective. Binding of single-stranded DNA to enolase reduces the reaction of protein histidyl residues with diethylpyrocarbonate. The inhibition of yeast enolase by single-stranded DNA is not total, and suggests the active site is not directly involved in the interaction. Binding of substrate may induce a conformational change in the enzyme that interferes with DNA binding and vice versa.
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
Oral yeast colonization throughout pregnancy.

PubMed

Rio, R; Simões-Silva, L; Garro, S; Silva, M-J; Azevedo, Á; Sampaio-Maia, B

2017-03-01

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. 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. 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. Pregnancy may favour oral yeast growth that may be associated with an acidic oral environment.
Quantification of 1,3-β-D-glucan from yeast added as a functional ingredient to bread.

PubMed

Rieder, Anne; Ballance, Simon; Böcker, Ulrike; Knutsen, Svein

2018-02-01

Due to their immunomodulatory effect, 1,3-β-G from yeast are used as functional ingredients, but reliable methods for their detection in foods are lacking. We have adapted a method based on fluorescence detection with aniline blue to quantify the amount of five commercial yeast β-glucan preparations added to crisp or yeast-leavened bread. This assay detected yeast β-glucan preparations added to different breads with an average recovery of 90, 96, 99 and 105%, while one of the preparations was overestimated, with an average recovery of 157%. The presence of cereal 1,3-1,4-β- D- glucans did not interfere with assay performance. The addition of 1,3-β-G at 0.2 and 0.5 g/100g is low compared to the recommended dose of 1,3-β-G per serving demonstrating assay sensitivity. However, more research is needed to fully understand the effect of 1,3-β-G conformation/structure on aniline blue interaction as well as the effect of baking on structure and dissolution properties of yeast β-glucans. Copyright © 2017 Elsevier Ltd. All rights reserved.
Electron transport chain in a thermotolerant yeast.

PubMed

Mejía-Barajas, Jorge A; Martínez-Mora, José A; Salgado-Garciglia, Rafael; Noriega-Cisneros, Ruth; Ortiz-Avila, Omar; Cortés-Rojo, Christian; Saavedra-Molina, Alfredo

2017-04-01

Yeasts capable of growing and surviving at high temperatures are regarded as thermotolerant. For appropriate functioning of cellular processes and cell survival, the maintenance of an optimal redox state is critical of reducing and oxidizing species. We studied mitochondrial functions of the thermotolerant Kluyveromyces marxianus SLP1 and the mesophilic OFF1 yeasts, through the evaluation of its mitochondrial membrane potential (ΔΨ m ), ATPase activity, electron transport chain (ETC) activities, alternative oxidase activity, lipid peroxidation. Mitochondrial membrane potential and the cytoplasmic free Ca 2+ ions (Ca 2+ cyt) increased in the SLP1 yeast when exposed to high temperature, compared with the mesophilic yeast OFF1. ATPase activity in the mesophilic yeast diminished 80% when exposed to 40° while the thermotolerant SLP1 showed no change, despite an increase in the mitochondrial lipid peroxidation. The SLP1 thermotolerant yeast exposed to high temperature showed a diminution of 33% of the oxygen consumption in state 4. The uncoupled state 3 of oxygen consumption did not change in the mesophilic yeast when it had an increase of temperature, whereas in the thermotolerant SLP1 yeast resulted in an increase of 2.5 times when yeast were grown at 30 o , while a decrease of 51% was observed when it was exposed to high temperature. The activities of the ETC complexes were diminished in the SLP1 when exposed to high temperature, but also it was distinguished an alternative oxidase activity. Our results suggest that the mitochondria state, particularly ETC state, is an important characteristic of the thermotolerance of the SLP1 yeast strain.
Cloning and in-silico analysis of beta-1,3-xylanase from psychrophilic yeast, Glaciozyma antarctica PI12

NASA Astrophysics Data System (ADS)

Nor, Nooraisyah Mohamad; Bakar, Farah Diba Abu; Mahadi, Nor Muhammad; Murad, Abdul Munir Abdul

2015-09-01

A beta-1,3-xylanase (EC 3.2.1.32) gene from psychrophilic yeast, Glaciozyma antarctica has been identified via genome data mining. The enzyme was grouped into GH26 family based on Carbohydrate Active Enzyme (CaZY) database. The molecular weight of this protein was predicted to be 42 kDa and is expected to be soluble for expression. The presence of signal peptide suggested that this enzyme may be released extracellularly into the marine environment of the host's habitat. This supports the theory that such enzymatic activity is required for degradation of nutrients of polysaccharide origins into simpler carbohydrates outside the environment before it could be taken up inside the cell. The sequence for this protein showed very little conservation (< 30%) with other beta-1,3-xylanases from available databases. Based on the phylogenetic analysis, this protein also showed distant relationship to other xylanases from eukaryotic origin. The protein may have undergone major substitution in its gene sequence order to adapt to the cold climate. This is the first report of beta-1,3-xylanase gene isolated from a psychrophilic yeast.

Effect of wine yeast monoculture practice on the biodiversity of non-Saccharomyces yeasts.

PubMed

Ganga, M A; Martínez, C

2004-01-01

The objective of this work was to study the effect of the use of Saccharomyces cerevisiae monocultures over the biodiversity of non-Saccharomyces yeasts in wine-producing areas in Chile. Microvinifications were carried out with grape musts of two areas. In one of them, the fermentation is carried out mainly in a spontaneous manner, whereas in the other the musts are inoculated with commercial yeasts. The isolated yeasts were identified by the internal transcribed (ITS)/restriction fragment length polymorphism technique. In the industrial production area less variability of yeast genera was observed as compared with the traditional area, an observation that is greatest at the end of the fermentation. Furthermore, a study of the production of extracellular enzymes was done. The majority of the yeasts showed at least one of the activities assayed with the exception of beta-glycosidase. The results suggest that in the industrialized area the diversity of yeasts is less in the traditional area. Likewise, the potentiality of the non-Saccharomyces yeasts as enzyme producers with industrial interest has been confirmed. This study shows the negative effect of the use of monocultures over the biodiversity of yeasts in wine-producing regions.
Dynamical analysis of yeast protein interaction network during the sake brewing process.

PubMed

Mirzarezaee, Mitra; Sadeghi, Mehdi; Araabi, Babak N

2011-12-01

Proteins interact with each other for performing essential functions of an organism. They change partners to get involved in various processes at different times or locations. Studying variations of protein interactions within a specific process would help better understand the dynamic features of the protein interactions and their functions. We studied the protein interaction network of Saccharomyces cerevisiae (yeast) during the brewing of Japanese sake. In this process, yeast cells are exposed to several stresses. Analysis of protein interaction networks of yeast during this process helps to understand how protein interactions of yeast change during the sake brewing process. We used gene expression profiles of yeast cells for this purpose. Results of our experiments revealed some characteristics and behaviors of yeast hubs and non-hubs and their dynamical changes during the brewing process. We found that just a small portion of the proteins (12.8 to 21.6%) is responsible for the functional changes of the proteins in the sake brewing process. The changes in the number of edges and hubs of the yeast protein interaction networks increase in the first stages of the process and it then decreases at the final stages.
El Paso/Yslete schools Get-Away Special Space Shuttle student projects

NASA Technical Reports Server (NTRS)

Azar, S. S.

1984-01-01

Student projects for the Get Away Special (GAS) space shuttle program were summarized. Experimental topics included: seed germination, shrimp growth, liquid lasers, planaria regeneration, fluid dynamics (wicking), soil molds, antibiotics, crystallization, the symbiosis of yeast and fungi, and the performance of electronic chips. A brief experimental design is included for each project.
Distinct Domestication Trajectories in Top-Fermenting Beer Yeasts and Wine Yeasts.

PubMed

Gonçalves, Margarida; Pontes, Ana; Almeida, Pedro; Barbosa, Raquel; Serra, Marta; Libkind, Diego; Hutzler, Mathias; Gonçalves, Paula; Sampaio, José Paulo

2016-10-24

Beer is one of the oldest alcoholic beverages and is produced by the fermentation of sugars derived from starches present in cereal grains. Contrary to lager beers, made by bottom-fermenting strains of Saccharomyces pastorianus, a hybrid yeast, ale beers are closer to the ancient beer type and are fermented by S. cerevisiae, a top-fermenting yeast. Here, we use population genomics to investigate (1) the closest relatives of top-fermenting beer yeasts; (2) whether top-fermenting yeasts represent an independent domestication event separate from those already described; (3) whether single or multiple beer yeast domestication events can be inferred; and (4) whether top-fermenting yeasts represent non-recombinant or recombinant lineages. Our results revealed that top-fermenting beer yeasts are polyphyletic, with a main clade composed of at least three subgroups, dominantly represented by the German, British, and wheat beer strains. Other beer strains were phylogenetically close to sake, wine, or bread yeasts. We detected genetic signatures of beer yeast domestication by investigating genes previously linked to brewing and using genome-wide scans. We propose that the emergence of the main clade of beer yeasts is related with a domestication event distinct from the previously known cases of wine and sake yeast domestication. The nucleotide diversity of the main beer clade more than doubled that of wine yeasts, which might be a consequence of fundamental differences in the modes of beer and wine yeast domestication. The higher diversity of beer strains could be due to the more intense and different selection regimes associated to brewing. Copyright © 2016 Elsevier Ltd. All rights reserved.
Cleavage of the SUN-domain protein Mps3 at its N-terminus regulates centrosome disjunction in budding yeast meiosis

PubMed Central

Koch, Bailey A.; Han, Xuemei

2017-01-01

Centrosomes organize microtubules and are essential for spindle formation and chromosome segregation during cell division. Duplicated centrosomes are physically linked, but how this linkage is dissolved remains unclear. Yeast centrosomes are tethered by a nuclear-envelope-attached structure called the half-bridge, whose components have mammalian homologues. We report here that cleavage of the half-bridge protein Mps3 promotes accurate centrosome disjunction in budding yeast. Mps3 is a single-pass SUN-domain protein anchored at the inner nuclear membrane and concentrated at the nuclear side of the half-bridge. Using the unique feature in yeast meiosis that centrosomes are linked for hours before their separation, we have revealed that Mps3 is cleaved at its nucleus-localized N-terminal domain, the process of which is regulated by its phosphorylation at serine 70. Cleavage of Mps3 takes place at the yeast centrosome and requires proteasome activity. We show that noncleavable Mps3 (Mps3-nc) inhibits centrosome separation during yeast meiosis. In addition, overexpression of mps3-nc in vegetative yeast cells also inhibits centrosome separation and is lethal. Our findings provide a genetic mechanism for the regulation of SUN-domain protein-mediated activities, including centrosome separation, by irreversible protein cleavage at the nuclear periphery. PMID:28609436
Quality improvement and geographical indication of cachaça (Brazilian spirit) by using locally selected yeast strains.

PubMed

Barbosa, E A; Souza, M T; Diniz, R H S; Godoy-Santos, F; Faria-Oliveira, F; Correa, L F M; Alvarez, F; Coutrim, M X; Afonso, R J C F; Castro, I M; Brandão, R L

2016-10-01

In order to improve the quality and to create a biological basis for obtainment of the protected denomination of origin (PDO), indigenous yeast were isolated and characterized for use in Salinas city (the Brazilian region of quality cachaça production). Seven thousand and two hundred yeast colonies from 15 Salinas city distilleries were screened based on their fermentative behaviour and the physicochemical composition of cachaça. Molecular polymorphic analyses were performed to characterize these isolates. Two Saccharomyces cerevisiae strains (nos. 678 and 680) showed appropriate characteristics to use in the cachaça production: low levels of acetaldehyde and methanol, and high ethyl lactate/ethyl acetate ratio respectively. They also presented polymorphic characteristics more closely related between themselves even when compared to other strains from Salinas. The application of selected yeast to cachaça production can contribute for the improvement of the quality product as well as be used as a natural marker for PDO. This study suggests that the use of selected yeast strains could contribute to obtain a cachaça similar to those produced traditionally, while getting wide acceptation in the market, yet presenting more homogeneous organoleptic characteristics, and thus contributing to the PDO implementation. © 2016 The Society for Applied Microbiology.
Draft genome sequence of the D-Xylose-Fermenting yeast Spathaspora xylofermentans UFMG-HMD23.3

USDA-ARS?s Scientific Manuscript database

Here, we report the draft genome sequence of the yeast Spathaspora xylofermentans UFMG-HMD23.3 (CBMAI 1427=CBS 12681), a D-xylose fermenting yeast isolated from the Amazonian forest. The genome consists of 298 contigs, with a total size of 15.1 Mb, including the mitochondrial genome, and 5,948 predi...
Brewing characteristics of piezosensitive sake yeasts

NASA Astrophysics Data System (ADS)

Nomura, Kazuki; Hoshino, Hirofumi; Igoshi, Kazuaki; Onozuka, Haruka; Tanaka, Erika; Hayashi, Mayumi; Yamazaki, Harutake; Takaku, Hiroaki; Iguchi, Akinori; Shigematsu, Toru

2018-04-01

Application of high hydrostatic pressure (HHP) treatment to food processing is expected as a non-thermal fermentation regulation technology that supresses over fermentation. However, the yeast Saccharomyces cerevisiae used for Japanese rice wine (sake) brewing shows high tolerance to HHP. Therefore, we aimed to generate pressure-sensitive (piezosensitive) sake yeast strains by mating sake with piezosensitive yeast strains to establish an HHP fermentation regulation technology and extend the shelf life of fermented foods. The results of phenotypic analyses showed that the generated yeast strains were piezosensitive and exhibited similar fermentation ability compared with the original sake yeast strain. In addition, primary properties of sake brewed using these strains, such as ethanol concentration, sake meter value and sake flavor compounds, were almost equivalent to those obtained using the sake yeast strain. These results suggest that the piezosensitive strains exhibit brewing characteristics essentially equivalent to those of the sake yeast strain.
Fission Yeast Sec3 and Exo70 Are Transported on Actin Cables and Localize the Exocyst Complex to Cell Poles

PubMed Central

Martin, Sophie G.

2012-01-01

The exocyst complex is essential for many exocytic events, by tethering vesicles at the plasma membrane for fusion. In fission yeast, polarized exocytosis for growth relies on the combined action of the exocyst at cell poles and myosin-driven transport along actin cables. We report here the identification of fission yeast Schizosaccharomyces pombe Sec3 protein, which we identified through sequence homology of its PH-like domain. Like other exocyst subunits, sec3 is required for secretion and cell division. Cells deleted for sec3 are only conditionally lethal and can proliferate when osmotically stabilized. Sec3 is redundant with Exo70 for viability and for the localization of other exocyst subunits, suggesting these components act as exocyst tethers at the plasma membrane. Consistently, Sec3 localizes to zones of growth independently of other exocyst subunits but depends on PIP2 and functional Cdc42. FRAP analysis shows that Sec3, like all other exocyst subunits, localizes to cell poles largely independently of the actin cytoskeleton. However, we show that Sec3, Exo70 and Sec5 are transported by the myosin V Myo52 along actin cables. These data suggest that the exocyst holocomplex, including Sec3 and Exo70, is present on exocytic vesicles, which can reach cell poles by either myosin-driven transport or random walk. PMID:22768263
Endocytosis and Vacuolar Degradation of the Yeast Cell Surface Glucose Sensors Rgt2 and Snf3*

PubMed Central

Roy, Adhiraj; Kim, Jeong-Ho

2014-01-01

Sensing and signaling the presence of extracellular glucose is crucial for the yeast Saccharomyces cerevisiae because of its fermentative metabolism, characterized by high glucose flux through glycolysis. The yeast senses glucose through the cell surface glucose sensors Rgt2 and Snf3, which serve as glucose receptors that generate the signal for induction of genes involved in glucose uptake and metabolism. Rgt2 and Snf3 detect high and low glucose concentrations, respectively, perhaps because of their different affinities for glucose. Here, we provide evidence that cell surface levels of glucose sensors are regulated by ubiquitination and degradation. The glucose sensors are removed from the plasma membrane through endocytosis and targeted to the vacuole for degradation upon glucose depletion. The turnover of the glucose sensors is inhibited in endocytosis defective mutants, and the sensor proteins with a mutation at their putative ubiquitin-acceptor lysine residues are resistant to degradation. Of note, the low affinity glucose sensor Rgt2 remains stable only in high glucose grown cells, and the high affinity glucose sensor Snf3 is stable only in cells grown in low glucose. In addition, constitutively active, signaling forms of glucose sensors do not undergo endocytosis, whereas signaling defective sensors are constitutively targeted for degradation, suggesting that the stability of the glucose sensors may be associated with their ability to sense glucose. Therefore, our findings demonstrate that the amount of glucose available dictates the cell surface levels of the glucose sensors and that the regulation of glucose sensors by glucose concentration may enable yeast cells to maintain glucose sensing activity at the cell surface over a wide range of glucose concentrations. PMID:24451370
Conversion of deoxynivalenol to 3-acetyldeoxynivalenol in barley-derived fuel ethanol co-products with yeast expressing trichothecene 3-O-acetyltransferases

PubMed Central

2011-01-01

Background The trichothecene mycotoxin deoxynivalenol (DON) may be concentrated in distillers dried grains with solubles (DDGS; a co-product of fuel ethanol fermentation) when grain containing DON is used to produce fuel ethanol. Even low levels of DON (≤ 5 ppm) in DDGS sold as feed pose a significant threat to the health of monogastric animals. New and improved strategies to reduce DON in DDGS need to be developed and implemented to address this problem. Enzymes known as trichothecene 3-O-acetyltransferases convert DON to 3-acetyldeoxynivalenol (3ADON), and may reduce its toxicity in plants and animals. Results Two Fusarium trichothecene 3-O-acetyltransferases (FgTRI101 and FfTRI201) were cloned and expressed in yeast (Saccharomyces cerevisiae) during a series of small-scale ethanol fermentations using barley (Hordeum vulgare). DON was concentrated 1.6 to 8.2 times in DDGS compared with the starting ground grain. During the fermentation process, FgTRI101 converted 9.2% to 55.3% of the DON to 3ADON, resulting in DDGS with reductions in DON and increases in 3ADON in the Virginia winter barley cultivars Eve, Thoroughbred and Price, and the experimental line VA06H-25. Analysis of barley mashes prepared from the barley line VA04B-125 showed that yeast expressing FfTRI201 were more effective at acetylating DON than those expressing FgTRI101; DON conversion for FfTRI201 ranged from 26.1% to 28.3%, whereas DON conversion for FgTRI101 ranged from 18.3% to 21.8% in VA04B-125 mashes. Ethanol yields were highest with the industrial yeast strain Ethanol Red®, which also consumed galactose when present in the mash. Conclusions This study demonstrates the potential of using yeast expressing a trichothecene 3-O-acetyltransferase to modify DON during commercial fuel ethanol fermentation. PMID:21888629
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 utilis...
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 acid...
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 acid...
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 acid...
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 acid...
Evolutionary History of Ascomyceteous Yeasts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haridas, Sajeet; Riley, Robert; Salamov, Asaf

2014-06-06

Yeasts are important for many industrial and biotechnological processes and show remarkable diversity despite morphological similarities. We have sequenced the genomes of 16 ascomycete yeasts of taxonomic and industrial importance including members of Saccharomycotina and Taphrinomycotina. A comparison of these with several other previously published yeast genomes have added increased confidence to the phylogenetic positions of previously poorly placed species including Saitoella complicata, Babjeviella inositovora and Metschnikowia bicuspidata. Phylogenetic analysis also showed that yeasts with alternative nuclear codon usage where CUG encodes serine instead of leucine are monophyletic within the Saccharomycotina. Most of the yeasts have compact genomes with amore » large fraction of single exon genes with Lipomyces starkeyi and the previously published Pneumocystis jirovecii being notable exceptions. Intron analysis suggests that early diverging species have more introns. We also observed a large number of unclassified lineage specific non-simple repeats in these genomes.« less
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.
Is the yeast a relevant model for aging of multicellular organisms? An insight from the total lifespan of Saccharomyces cerevisiae.

PubMed

Zadrag, Renata; Bartosz, Grzegorz; Bilinski, Tomasz

2008-12-01

The applicability of the free radical theory of aging to the yeast S. cerevisiae is a matter of debate. In order to get an insight into this question, we studied the reproductive potential (the number of buds produced), reproductive lifespan (the time during which a yeast cell is able to divide), postreproductive lifespan (duration of life of yeast cells which ceased to divide) and total lifespan (sum of reproductive lifespan and postreproductive lifespan) of three isogenic pairs of yeast strains. Each pair contained a parent strain and a disruptant of gene(s) coding for important antioxidant enzyme(s) (CuZn-superoxide dismutase, all five peroxiredoxins or glutaredoxin 5). Although the reproductive potential was decreased in all antioxidant enzyme-deficient mutants, the differences in the reproductive lifespan between the parent strains and the mutants were less pronounced while postreproductive lifespan and total lifespan were not diminished in the mutants. These results suggest that either the free-radical theory of aging is not applicable to S. cerevisiae or that this yeast is not a proper model organism for the study of aging of higher organisms. In our opinion the latter possibility is more apparent and the increase in cell volume (unavoidable for a cell propagating by budding) rather than accumulation of oxidative damage may be the main reason for the cessation of budding (and perhaps postreproductive death) in S. cerevisiae.
21 CFR 172.898 - Bakers yeast glycan.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Bakers yeast glycan. 172.898 Section 172.898 Food... 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, and dried cell walls of the yeast...

Synthesis of recombinant human parainfluenza virus 1 and 3 nucleocapsid proteins in yeast Saccharomyces cerevisiae.

PubMed

Juozapaitis, Mindaugas; Zvirbliene, Aurelija; Kucinskaite, Indre; Sezaite, Indre; Slibinskas, Rimantas; Coiras, Mayte; de Ory Manchon, Fernando; López-Huertas, María Rosa; Pérez-Breña, Pilar; Staniulis, Juozas; Narkeviciute, Irena; Sasnauskas, Kestutis

2008-05-01

Human parainfluenza virus types 1 and 3 (HPIV1 and HPIV3, respectively), members of the virus family Paramyxoviridae, are common causes of lower respiratory tract infections in infants, young children, the immunocompromised, the chronically ill, and the elderly. In order to synthesize recombinant HPIV1 and HPIV3 nucleocapsid proteins, the coding sequences were cloned into the yeast Saccharomyces cerevisiae expression vector pFGG3 under control of GAL7 promoter. A high level of recombinant virus nucleocapsid proteins expression (20-24 mg l(-1) of yeast culture) was obtained. Electron microscopy demonstrated the assembly of typical herring-bone structures of purified recombinant nucleocapsid proteins, characteristic for other paramyxoviruses. These structures contained host RNA, which was resistant to RNase treatment. The nucleocapsid proteins were stable in yeast and were easily purified by caesium chloride gradient ultracentrifugation. Therefore, this system proved to be simple, efficient and cost-effective, suitable for high-level production of parainfluenza virus nucleocapsids as nucleocapsid-like particles. When used as coating antigens in an indirect ELISA, the recombinant N proteins reacted with sera of patients infected with HPIV1 or 3. Serological assays to detect HPIV-specific antibodies could be designed on this basis.
Evidence for a high mutation rate at rapidly evolving yeast centromeres.

PubMed

Bensasson, Douda

2011-07-18

Although their role in cell division is essential, centromeres evolve rapidly in animals, plants and yeasts. Unlike the complex centromeres of plants and aminals, the point centromeres of Saccharomcyes yeasts can be readily sequenced to distinguish amongst the possible explanations for fast centromere evolution. Using DNA sequences of all 16 centromeres from 34 strains of Saccharomyces cerevisiae and population genomic data from Saccharomyces paradoxus, I show that centromeres in both species evolve 3 times more rapidly even than selectively unconstrained DNA. Exceptionally high levels of polymorphism seen in multiple yeast populations suggest that rapid centromere evolution does not result from the repeated selective sweeps expected under meiotic drive. I further show that there is little evidence for crossing-over or gene conversion within centromeres, although there is clear evidence for recombination in their immediate vicinity. Finally I show that the mutation spectrum at centromeres is consistent with the pattern of spontaneous mutation elsewhere in the genome. These results indicate that rapid centromere evolution is a common phenomenon in yeast species. Furthermore, these results suggest that rapid centromere evolution does not result from the mutagenic effect of gene conversion, but from a generalised increase in the mutation rate, perhaps arising from the unusual chromatin structure at centromeres in yeast and other eukaryotes.
A protein interaction network analysis for yeast integral membrane protein.

PubMed

Shi, Ming-Guang; Huang, De-Shuang; Li, Xue-Ling

2008-01-01

Although the yeast Saccharomyces cerevisiae is the best exemplified single-celled eukaryote, the vast number of protein-protein interactions of integral membrane proteins of Saccharomyces cerevisiae have not been characterized by experiments. Here, based on the kernel method of Greedy Kernel Principal Component analysis plus Linear Discriminant Analysis, we identify 300 protein-protein interactions involving 189 membrane proteins and get the outcome of a highly connected protein-protein interactions network. Furthermore, we study the global topological features of integral membrane proteins network of Saccharomyces cerevisiae. These results give the comprehensive description of protein-protein interactions of integral membrane proteins and reveal global topological and robustness of the interactome network at a system level. This work represents an important step towards a comprehensive understanding of yeast protein interactions.
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
Identification of uncommon oral yeasts from cancer patients by MALDI-TOF mass spectrometry.

PubMed

Aslani, Narges; Janbabaei, Ghasem; Abastabar, Mahdi; Meis, Jacques F; Babaeian, Mahasti; Khodavaisy, Sadegh; Boekhout, Teun; Badali, Hamid

2018-01-08

Opportunistic infections due to Candida species occur frequently in cancer patients because of their inherent immunosuppression. The aim of the present study was to investigate the epidemiology of yeast species from the oral cavity of patients during treatment for oncological and haematological malignancies. MALDI-TOF was performed to identify yeasts isolated from the oral cavity of 350 cancer patients. Moreover, antifungal susceptibility testing was performed in according to CLSI guidelines (M27-A3). Among 162 yeasts and yeast-like fungi isolated from the oral cavity of cancer patients, Candida albicans was the most common species (50.6%), followed by Candida glabrata (24.7%), Pichia kudriavzevii (Candida krusei (9.9%)), Candida tropicalis (4.3%), Candida dubliniensis (3.7%), Kluyveromyces marxianus (Candida kefyr (3.7%)) and Candida parapsilosis (1%). In addition, uncommon yeast species i.e., Saprochaete capitata, Saccharomyces cerevisiae, Clavispora lusitaniae (C. lusitaniae) and Pichia kluyveri (C. eremophila) were recovered from oral lesions. Oral colonization by C. albicans, non-albicans Candida species and uncommon yeasts were as follow; 55%, 44% and 1%, whereas oral infection due to C. albicans was 33.3%, non-albicans Candida species 60.6%, and uncommon yeasts 6.1%. Poor oral hygiene and xerostomia were identified as independent risk factors associated with oral yeast colonization. The overall resistance to fluconazole was 11.7% (19/162). Low MIC values were observed for anidulafungin for all Candida and uncommon yeast species. This current study provides insight into the prevalence and susceptibility profiles of Candida species, including emerging Candida species and uncommon yeasts, isolated from the oral cavity of Iranian cancer patients. The incidence of oral candidiasis was higher amongst patients with hematological malignancies. The majority of oral infections were caused by non-albicans Candida species which were often more resistant to anti
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, Saccharomyces...
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) The...
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) The...
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
Ty3 Retrotransposon Hijacks Mating Yeast RNA Processing Bodies to Infect New Genomes

PubMed Central

Kaake, Robyn; Dawson, Anthony R.; Matheos, Dina; Nagashima, Kunio; Sitlani, Parth; Patterson, Kurt; Chang, Ivan; Huang, Lan; Sandmeyer, Suzanne

2015-01-01

Retrotransposition of the budding yeast long terminal repeat retrotransposon Ty3 is activated during mating. In this study, proteins that associate with Ty3 Gag3 capsid protein during virus-like particle (VLP) assembly were identified by mass spectrometry and screened for roles in mating-stimulated retrotransposition. Components of RNA processing bodies including DEAD box helicases Dhh1/DDX6 and Ded1/DDX3, Sm-like protein Lsm1, decapping protein Dcp2, and 5’ to 3’ exonuclease Xrn1 were among the proteins identified. These proteins associated with Ty3 proteins and RNA, and were required for formation of Ty3 VLP retrosome assembly factories and for retrotransposition. Specifically, Dhh1/DDX6 was required for normal levels of Ty3 genomic RNA, and Lsm1 and Xrn1 were required for association of Ty3 protein and RNA into retrosomes. This role for components of RNA processing bodies in promoting VLP assembly and retrotransposition during mating in a yeast that lacks RNA interference, contrasts with roles proposed for orthologous components in animal germ cell ribonucleoprotein granules in turnover and epigenetic suppression of retrotransposon RNAs. PMID:26421679
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, and...
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, and...
Yeast Communities of Diverse Drosophila Species: Comparison of Two Symbiont Groups in the Same Hosts

PubMed Central

Eisen, Jonathan A.; Kopp, Artyom

2012-01-01

The combination of ecological diversity with genetic and experimental tractability makes Drosophila a powerful model for the study of animal-associated microbial communities. Despite the known importance of yeasts in Drosophila physiology, behavior, and fitness, most recent work has focused on Drosophila-bacterial interactions. In order to get a more complete understanding of the Drosophila microbiome, we characterized the yeast communities associated with different Drosophila species collected around the world. We focused on the phylum Ascomycota because it constitutes the vast majority of the Drosophila-associated yeasts. Our sampling strategy allowed us to compare the distribution and structure of the yeast and bacterial communities in the same host populations. We show that yeast communities are dominated by a small number of abundant taxa, that the same yeast lineages are associated with different host species and populations, and that host diet has a greater effect than host species on yeast community composition. These patterns closely parallel those observed in Drosophila bacterial communities. However, we do not detect a significant correlation between the yeast and bacterial communities of the same host populations. Comparative analysis of different symbiont groups provides a more comprehensive picture of host-microbe interactions. Future work on the role of symbiont communities in animal physiology, ecological adaptation, and evolution would benefit from a similarly holistic approach. PMID:22885750
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
Acetic acid production from food wastes using yeast and acetic acid bacteria micro-aerobic fermentation.

PubMed

Li, Yang; He, Dongwei; Niu, Dongjie; Zhao, Youcai

2015-05-01

In this study, yeast and acetic acid bacteria strains were adopted to enhance the ethanol-type fermentation resulting to a volatile fatty acids yield of 30.22 g/L, and improve acetic acid production to 25.88 g/L, with food wastes as substrate. In contrast, only 12.81 g/L acetic acid can be obtained in the absence of strains. The parameters such as pH, oxidation reduction potential and volatile fatty acids were tested and the microbial diversity of different strains and activity of hydrolytic ferment were investigated to reveal the mechanism. The optimum pH and oxidation reduction potential for the acetic acid production were determined to be at 3.0-3.5 and -500 mV, respectively. Yeast can convert organic matters into ethanol, which is used by acetic acid bacteria to convert the organic wastes into acetic acid. The acetic acid thus obtained from food wastes micro-aerobic fermentation liquid could be extracted by distillation to get high-pure acetic acid.
Yeast and Fungal Prions: Amyloid-Handling Systems, Amyloid Structure, and Prion Biology.

PubMed

Wickner, R B; Edskes, H K; Gorkovskiy, A; Bezsonov, E E; Stroobant, E E

2016-01-01

Yeast prions (infectious proteins) were discovered by their outré genetic properties and have become important models for an array of human prion and amyloid diseases. A single prion protein can become any of many distinct amyloid forms (called prion variants or strains), each of which is self-propagating, but with different biological properties (eg, lethal vs mild). The folded in-register parallel β sheet architecture of the yeast prion amyloids naturally suggests a mechanism by which prion variant information can be faithfully transmitted for many generations. The yeast prions rely on cellular chaperones for their propagation, but can be cured by various chaperone imbalances. The Btn2/Cur1 system normally cures most variants of the [URE3] prion that arise. Although most variants of the [PSI+] and [URE3] prions are toxic or lethal, some are mild in their effects. Even the most mild forms of these prions are rare in the wild, indicating that they too are detrimental to yeast. The beneficial [Het-s] prion of Podospora anserina poses an important contrast in its structure, biology, and evolution to the yeast prions characterized thus far. Copyright © 2016 Elsevier Inc. All rights reserved.
Evidence for a high mutation rate at rapidly evolving yeast centromeres

PubMed Central

2011-01-01

Background Although their role in cell division is essential, centromeres evolve rapidly in animals, plants and yeasts. Unlike the complex centromeres of plants and aminals, the point centromeres of Saccharomcyes yeasts can be readily sequenced to distinguish amongst the possible explanations for fast centromere evolution. Results Using DNA sequences of all 16 centromeres from 34 strains of Saccharomyces cerevisiae and population genomic data from Saccharomyces paradoxus, I show that centromeres in both species evolve 3 times more rapidly even than selectively unconstrained DNA. Exceptionally high levels of polymorphism seen in multiple yeast populations suggest that rapid centromere evolution does not result from the repeated selective sweeps expected under meiotic drive. I further show that there is little evidence for crossing-over or gene conversion within centromeres, although there is clear evidence for recombination in their immediate vicinity. Finally I show that the mutation spectrum at centromeres is consistent with the pattern of spontaneous mutation elsewhere in the genome. Conclusions These results indicate that rapid centromere evolution is a common phenomenon in yeast species. Furthermore, these results suggest that rapid centromere evolution does not result from the mutagenic effect of gene conversion, but from a generalised increase in the mutation rate, perhaps arising from the unusual chromatin structure at centromeres in yeast and other eukaryotes. PMID:21767380
Checkpoint independence of most DNA replication origins in fission yeast

PubMed Central

Mickle, Katie L; Ramanathan, Sunita; Rosebrock, Adam; Oliva, Anna; Chaudari, Amna; Yompakdee, Chulee; Scott, Donna; Leatherwood, Janet; Huberman, Joel A

2007-01-01

Background In budding yeast, the replication checkpoint slows progress through S phase by inhibiting replication origin firing. In mammals, the replication checkpoint inhibits both origin firing and replication fork movement. To find out which strategy is employed in the fission yeast, Schizosaccharomyces pombe, we used microarrays to investigate the use of origins by wild-type and checkpoint-mutant strains in the presence of hydroxyurea (HU), which limits the pool of deoxyribonucleoside triphosphates (dNTPs) and activates the replication checkpoint. The checkpoint-mutant cells carried deletions either of rad3 (which encodes the fission yeast homologue of ATR) or cds1 (which encodes the fission yeast homologue of Chk2). Results Our microarray results proved to be largely consistent with those independently obtained and recently published by three other laboratories. However, we were able to reconcile differences between the previous studies regarding the extent to which fission yeast replication origins are affected by the replication checkpoint. We found (consistent with the three previous studies after appropriate interpretation) that, in surprising contrast to budding yeast, most fission yeast origins, including both early- and late-firing origins, are not significantly affected by checkpoint mutations during replication in the presence of HU. A few origins (~3%) behaved like those in budding yeast: they replicated earlier in the checkpoint mutants than in wild type. These were located primarily in the heterochromatic subtelomeric regions of chromosomes 1 and 2. Indeed, the subtelomeric regions defined by the strongest checkpoint restraint correspond precisely to previously mapped subtelomeric heterochromatin. This observation implies that subtelomeric heterochromatin in fission yeast differs from heterochromatin at centromeres, in the mating type region, and in ribosomal DNA, since these regions replicated at least as efficiently in wild-type cells as in
Influence of gamma radiation on ethanol production from yeast.

PubMed

Del-Mastro, N L; Gimenes, J J; Villavicencio, A L

1988-01-01

The effect of up to 6,000 Gray (Gy; 1 Gy = 1 J/k) 60Co gamma irradiation on the fermentative capacity of two strains of yeast cells is reported. Ethanol production by the irradiated cells was unchanged for both strains at 3,000 Gy and reduced 43% for only one strain at 6,000 Gy in spite of a marked decrease in viability at higher doses (2-8% at 3,000 Gy and 0.01% at 6,000 Gy). These results suggest that the yeast fermentation system for converting sugar to alcohol is a relatively radioresistant process and not inhibited by the stable by-products produced during irradiation. Furthermore, these data indicate that radiation polymerization for immobilizing these cells should not interfere with their fermentation capacity.
The presence of a mycangium in European Sinodendron cylindricum (Coleoptera: Lucanidae) and the associated yeast symbionts

PubMed Central

Tanahashi, Masahiko; Hawes, Colin J.

2016-01-01

Part of the exoskeleton of some wood-inhabiting insects is modified to form a mycangium, which is a specialized organ used to convey fungal spores or yeasts to their offspring. Although most stag beetles (Coleoptera: Lucanidae) are known to have female-specific mycangia and associated yeast symbionts, the evolutionary origin of the mycangium in this group remains unresolved. Here, we report the presence of a mycangium and associated yeast symbionts in the European horned stag beetle Sinodendron cylindricum (L.), which belongs to an ancestral clade of the Lucanidae. The mycangium of S. cylindricum is shown to be female-specific and have the same developmental origin as that of other stag beetles. A total of five yeast strains were isolated from adult mycangia and larval gut of S. cylindricum. Of these, we suggest that SICYAM1 is an undescribed yeast with taxonomic novelty, and have identified SICYLG3 as the xylose-fermenting yeast Scheffersomyces insectosa using nuclear ribosomal RNA and ITS sequences. The remaining three yeast strains, SICYAM2, SICYLG1, and SICYLG2, were assigned to the genus Sugiyamaella. Yeast density in the adult mycangium was lower than that of the more evolutionarily advanced stag beetles, the European Lucanus cervus (L.) and Dorcus parallelipipedus (L.), which were also examined in this study. No living yeasts were isolated from the adult guts. However, a third instar larva of S. cylindricum harbored 104–106 living yeasts in each gut region, which suggests that gut yeasts play an important role in these wood-feeding larvae. PMID:27432353

Recurrent Rearrangement during Adaptive Evolution in an Interspecific Yeast Hybrid Suggests a Model for Rapid Introgression

PubMed Central

Dunn, Barbara; Paulish, Terry; Stanbery, Alison; Piotrowski, Jeff; Koniges, Gregory; Kroll, Evgueny; Louis, Edward J.; Liti, Gianni; Sherlock, Gavin; Rosenzweig, Frank

2013-01-01

Genome rearrangements are associated with eukaryotic evolutionary processes ranging from tumorigenesis to speciation. Rearrangements are especially common following interspecific hybridization, and some of these could be expected to have strong selective value. To test this expectation we created de novo interspecific yeast hybrids between two diverged but largely syntenic Saccharomyces species, S. cerevisiae and S. uvarum, then experimentally evolved them under continuous ammonium limitation. We discovered that a characteristic interspecific genome rearrangement arose multiple times in independently evolved populations. We uncovered nine different breakpoints, all occurring in a narrow ∼1-kb region of chromosome 14, and all producing an “interspecific fusion junction” within the MEP2 gene coding sequence, such that the 5′ portion derives from S. cerevisiae and the 3′ portion derives from S. uvarum. In most cases the rearrangements altered both chromosomes, resulting in what can be considered to be an introgression of a several-kb region of S. uvarum into an otherwise intact S. cerevisiae chromosome 14, while the homeologous S. uvarum chromosome 14 experienced an interspecific reciprocal translocation at the same breakpoint within MEP2, yielding a chimaeric chromosome; these events result in the presence in the cell of two MEP2 fusion genes having identical breakpoints. Given that MEP2 encodes for a high-affinity ammonium permease, that MEP2 fusion genes arise repeatedly under ammonium-limitation, and that three independent evolved isolates carrying MEP2 fusion genes are each more fit than their common ancestor, the novel MEP2 fusion genes are very likely adaptive under ammonium limitation. Our results suggest that, when homoploid hybrids form, the admixture of two genomes enables swift and otherwise unavailable evolutionary innovations. Furthermore, the architecture of the MEP2 rearrangement suggests a model for rapid introgression, a phenomenon seen in
Swa2, the yeast homolog of mammalian auxilin, is specifically required for the propagation of the prion variant [URE 3‐1

PubMed Central

Troisi, Elizabeth M.; Rockman, Michael E.; Nguyen, Phil P.; Oliver, Emily E.

2015-01-01

Summary Yeast prions require a core set of chaperone proteins including Sis1, Hsp70 and Hsp104 to generate new amyloid templates for stable propagation, yet emerging studies indicate that propagation of some prions requires additional chaperone activities, demonstrating chaperone specificity beyond the common amyloid requirements. To comprehensively assess such prion‐specific requirements for the propagation of the [URE 3] prion variant [URE 3‐1], we screened 12 yeast cytosolic J‐proteins, and here we report a novel role for the J‐protein Swa2/Aux1. Swa2 is the sole yeast homolog of the mammalian protein auxilin, which, like Swa2, functions in vesicle‐mediated endocytosis by disassembling the structural lattice formed by the protein clathrin. We found that, in addition to Sis1, [URE 3‐1] is specifically dependent upon Swa2, but not on any of the 11 other J‐proteins. Further, we show that [URE 3‐1] propagation requires both a functional J‐domain and the tetratricopeptide repeat (TPR) domain, but surprisingly does not require Swa2‐clathrin binding. Because the J‐domain of Swa2 can be replaced with the J‐domains of other proteins, our data strongly suggest that prion‐chaperone specificity arises from the Swa2 TPR domain and supports a model where Swa2 acts through Hsp70, most likely to provide additional access points for Hsp104 to promote prion template generation. PMID:26031938
BH3-only protein Bim inhibits activity of antiapoptotic members of Bcl-2 family when expressed in yeast.

PubMed

Juhásová, Barbora; Mentel, Marek; Bhatia-Kiššová, Ingrid; Zeman, Igor; Kolarov, Jordan; Forte, Michael; Polčic, Peter

2011-09-02

Proteins of the Bcl-2 family regulate programmed cell death in mammals by promoting the release of cytochrome c from mitochondria in response to various proapoptotic stimuli. The mechanism by which BH3-only members of the family activate multidomain proapoptotic proteins Bax and Bak to form a pore in mitochondrial membranes remains under dispute. We report that cell death promoting activity of BH3-only protein Bim can be reconstituted in yeast when both Bax and antiapoptotic protein Bcl-X(L) are present, suggesting that Bim likely activates Bax indirectly by inhibiting antiapoptotic proteins. Copyright © 2011 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
Budding yeast telomerase RNA transcription termination is dictated by the Nrd1/Nab3 non-coding RNA termination pathway

PubMed Central

Noël, Jean-François; Larose, Stéphanie; Abou Elela, Sherif; Wellinger, Raymund J.

2012-01-01

The RNA component of budding yeast telomerase (Tlc1) occurs in two forms, a non-polyadenylated form found in functional telomerase and a rare polyadenylated version with unknown function. Previous work suggested that the functional Tlc1 polyA− RNA is processed from the polyA+ form, but the mechanisms regulating its transcription termination and 3′-end formation remained unclear. Here we examined transcription termination of Tlc1 RNA in the sequences 3′ of the TLC1 gene and relate it to telomere maintenance. Strikingly, disruption of all probable or cryptic polyadenylation signals near the 3′-end blocked the accumulation of the previously reported polyA+ RNA without affecting the level, function or specific 3′ nucleotide of the mature polyA− form. A genetic approach analysing TLC1 3′-end sequences revealed that transcription terminates upstream of the polyadenylation sites. Furthermore, the results also demonstrate that the function of this Tlc1 terminator depends on the Nrd1/Nab3 transcription termination pathway. The data thus show that transcription termination of the budding yeast telomerase RNA occurs as that of snRNAs and Tlc1 functions in telomere maintenance are not strictly dependent on a polyadenylated precursor, even if the polyA+ form can serve as intermediate in a redundant termination/maturation pathway. PMID:22379137
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, Saccharomyces...
Biogas Production from Brewer’s Yeast Using an Anaerobic Sequencing Batch Reactor

PubMed Central

2017-01-01

Summary Renewable energy sources are becoming increasingly important in the beverage and food industries. In the brewing industry, a significant percentage of the used raw materials finishes the process as secondary resource or waste. The research on the anaerobic digestion of brewer’s yeast has been scarce until recent years. One of the reasons for this is its use as a secondary resource in the food industry and as cattle feed. Additionally, market value of brewer’s yeast is higher than its energy value. Due to the increase of energy prices, brewer’s yeast has become of interest as energy substrate despite its difficult degradability in anaerobic conditions. The anaerobic co-digestion of brewer’s yeast and anaerobically treated brewery wastewater was studied using a pilot-scale anaerobic sequencing batch reactor (ASBR) seeded with granular biomass. The experiments showed very good and stable operation with an organic loading rate of up to 8.0 kg/(m3·day), and with a maximum achieved organic loading rate of 13.6 kg/(m3·day) in a single cycle. A specific biogas productivity of over 0.430 m3/kg of the total chemical oxygen demand (COD) inserted, and total COD removal efficiencies of over 90% were achieved. This study suggests that the brewer’s yeast can be successfully digested in an ASBR without adverse effects on the biogas production from brewer’s yeast/wastewater mixtures of up to 8% (by volume). By using the brewer’s yeast in the ASBR process, the biogas production from brewery wastewater could be increased by 50%. PMID:28867948
Genetic and Biochemical Analysis of High Iron Toxicity in Yeast

PubMed Central

Lin, Huilan; Li, Liangtao; Jia, Xuan; Ward, Diane McVey; Kaplan, Jerry

2011-01-01

Iron storage in yeast requires the activity of the vacuolar iron transporter Ccc1. Yeast with an intact CCC1 are resistant to iron toxicity, but deletion of CCC1 renders yeast susceptible to iron toxicity. We used genetic and biochemical analysis to identify suppressors of high iron toxicity in Δccc1 cells to probe the mechanism of high iron toxicity. All genes identified as suppressors of high iron toxicity in aerobically grown Δccc1 cells encode organelle iron transporters including mitochondrial iron transporters MRS3, MRS4, and RIM2. Overexpression of MRS3 suppressed high iron toxicity by decreasing cytosolic iron through mitochondrial iron accumulation. Under anaerobic conditions, Δccc1 cells were still sensitive to high iron toxicity, but overexpression of MRS3 did not suppress iron toxicity and did not result in mitochondrial iron accumulation. We conclude that Mrs3/Mrs4 can sequester iron within mitochondria under aerobic conditions but not anaerobic conditions. We show that iron toxicity in Δccc1 cells occurred under both aerobic and anaerobic conditions. Microarray analysis showed no evidence of oxidative damage under anaerobic conditions, suggesting that iron toxicity may not be solely due to oxidative damage. Deletion of TSA1, which encodes a peroxiredoxin, exacerbated iron toxicity in Δccc1 cells under both aerobic and anaerobic conditions, suggesting a unique role for Tsa1 in iron toxicity. PMID:21115478
Chemical signaling and insect attraction is a conserved trait in yeasts.

PubMed

Becher, Paul G; Hagman, Arne; Verschut, Vasiliki; Chakraborty, Amrita; Rozpędowska, Elżbieta; Lebreton, Sébastien; Bengtsson, Marie; Flick, Gerhard; Witzgall, Peter; Piškur, Jure

2018-03-01

. Moreover, volatiles emitted by yeasts are commonly found also in flowers and attract many insect species. The collective evidence suggests that the release of volatile signals by yeasts is a widespread and phylogenetically ancient trait, and that insect-yeast communication evolved prior to the emergence of flowering plants. Co-occurrence of the same attractant signals in yeast and flowers suggests that yeast-insect communication may have contributed to the evolution of insect-mediated pollination in flowers.
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 from...
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 from...
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 from...
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 from...
Saccharomyces cerevisiae: a sexy yeast with a prion problem.

PubMed

Kelly, Amy C; Wickner, Reed B

2013-01-01

Yeast prions are infectious proteins that spread exclusively by mating. The frequency of prions in the wild therefore largely reflects the rate of spread by mating counterbalanced by prion growth slowing effects in the host. We recently showed that the frequency of outcross mating is about 1% of mitotic doublings with 23-46% of total matings being outcrosses. These findings imply that even the mildest forms of the [PSI+], [URE3] and [PIN+] prions impart > 1% growth/survival detriment on their hosts. Our estimate of outcrossing suggests that Saccharomyces cerevisiae is far more sexual than previously thought and would therefore be more responsive to the adaptive effects of natural selection compared with a strictly asexual yeast. Further, given its large effective population size, a growth/survival detriment of > 1% for yeast prions should strongly select against prion-infected strains in wild populations of Saccharomyces cerevisiae.
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.
An original method for producing acetaldehyde and diacetyl by yeast fermentation.

PubMed

Rosca, Irina; Petrovici, Anca Roxana; Brebu, Mihai; Stoica, Irina; Minea, Bogdan; Marangoci, Narcisa

In this study a natural culture medium that mimics the synthetic yeast peptone glucose medium used for yeast fermentations was designed to screen and select yeasts capable of producing high levels of diacetyl and acetaldehyde. The presence of whey powder and sodium citrate in the medium along with manganese and magnesium sulfate enhanced both biomass and aroma development. A total of 52 yeasts strains were cultivated in two different culture media, namely, yeast peptone glucose medium and yeast acetaldehyde-diacetyl medium. The initial screening of the strains was based on the qualitative reaction of the acetaldehyde with Schiff's reagent (violet color) and diacetyl with Brady's reagent (yellow precipitate). The fermented culture media of 10 yeast strains were subsequently analyzed by gas chromatography to quantify the concentration of acetaldehyde and diacetyl synthesized. Total titratable acidity values indicated that a total titratable acidity of 5.5°SH, implying culture medium at basic pH, was more favorable for the acetaldehyde biosynthesis using strain D15 (Candida lipolytica; 96.05mgL -1 acetaldehyde) while a total titratable acidity value of 7°SH facilitated diacetyl flavor synthesis by strain D38 (Candida globosa; 3.58mgL -1 diacetyl). Importantly, the results presented here suggest that this can be potentially used in the baking industry. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.
Low bioaccessibility of vitamin D2 from yeast-fortified bread compared to crystalline D2 bread and D3 from fluid milks.

PubMed

Lipkie, Tristan E; Ferruzzi, Mario G; Weaver, Connie M

2016-11-09

The assessment of the efficacy of dietary and supplemental vitamin D tends to be confounded by differences in the serum 25-hydroxyvitamin D response between vitamin D 2 and vitamin D 3 . Serum response differences from these vitamers may be due to differences in bioavailability. To address this specifically, the bioaccessibility was assessed for vitamin D 2 from breads fortified with UV-treated yeast, and a benchmark against staple vitamin D 3 fortified foods including bovine milks and infant formula, as well as crystalline vitamin D 2 fortified bread. Fortified foods were subjected to a three-stage static in vitro digestion model, and vitamin D was analyzed by HPLC-MS. Vitamin D bioaccessibility was significantly greater from bovine milks and infant formula (71-85%) than from yeast-fortified sandwich breads (6-7%). Bioaccessibility was not different between whole wheat and white wheat bread (p > 0.05), but was ∼4× lower from yeast-fortified bread than from crystalline vitamin D 2 fortified bread (p < 0.05). Intact yeast cells were observed in the digesta of yeast fortified bread. These results indicate that the low bioavailability of yeast D 2 in comparison to other vitamin D 2 sources is likely due to entrapment within a less digestible yeast matrix and not only to metabolic differences between vitamins D 2 and D 3 .
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.
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.
Targeting of Chitin Synthase 3 to Polarized Growth Sites in Yeast Requires Chs5p and Myo2p

PubMed Central

Santos, Beatriz; Snyder, Michael

1997-01-01

Chitin is an essential structural component of the yeast cell wall whose deposition is regulated throughout the yeast life cycle. The temporal and spatial regulation of chitin synthesis was investigated during vegetative growth and mating of Saccharomyces cerevisiae by localization of the putative catalytic subunit of chitin synthase III, Chs3p, and its regulator, Chs5p. Immunolocalization of epitope-tagged Chs3p revealed a novel localization pattern that is cell cycledependent. Chs3p is polarized as a diffuse ring at the incipient bud site and at the neck between the mother and bud in small-budded cells; it is not found at the neck in large-budded cells containing a single nucleus. In large-budded cells undergoing cytokinesis, it reappears as a ring at the neck. In cells responding to mating pheromone, Chs3p is found throughout the projection. The appearance of Chs3p at cortical sites correlates with times that chitin synthesis is expected to occur. In addition to its localization at the incipient bud site and neck, Chs3p is also found in cytoplasmic patches in cells at different stages of the cell cycle. Epitope-tagged Chs5p also localizes to cytoplasmic patches; these patches contain Kex2p, a late Golgi-associated enzyme. Unlike Chs3p, Chs5p does not accumulate at the incipient bud site or neck. Nearly all Chs3p patches contain Chs5p, whereas some Chs5p patches lack detectable Chs3p. In the absence of Chs5p, Chs3p localizes in cytoplasmic patches, but it is no longer found at the neck or the incipient bud site, indicating that Chs5p is required for the polarization of Chs3p. Furthermore, Chs5p localization is not affected either by temperature shift or by the myo2-66 mutation, however, Chs3p polarization is affected by temperature shift and myo2-66. We suggest a model in which Chs3p polarization to cortical sites in yeast is dependent on both Chs5p and the actin cytoskeleton/Myo2p. PMID:9008706
LegC3, an Effector Protein from Legionella pneumophila, Inhibits Homotypic Yeast Vacuole Fusion In Vivo and In Vitro

PubMed Central

Bennett, Terry L.; Kraft, Shannon M.; Reaves, Barbara J.; Mima, Joji; O’Brien, Kevin M.; Starai, Vincent J.

2013-01-01

During infection, the intracellular pathogenic bacterium Legionella pneumophila causes an extensive remodeling of host membrane trafficking pathways, both in the construction of a replication-competent vacuole comprised of ER-derived vesicles and plasma membrane components, and in the inhibition of normal phagosome:endosome/lysosome fusion pathways. Here, we identify the LegC3 secreted effector protein from L. pneumophila as able to inhibit a SNARE- and Rab GTPase-dependent membrane fusion pathway in vitro, the homotypic fusion of yeast vacuoles (lysosomes). This vacuole fusion inhibition appeared to be specific, as similar secreted coiled-coiled domain containing proteins from L. pneumophila, LegC7/YlfA and LegC2/YlfB, did not inhibit vacuole fusion. The LegC3-mediated fusion inhibition was reversible by a yeast cytosolic extract, as well as by a purified soluble SNARE, Vam7p. LegC3 blocked the formation of trans-SNARE complexes during vacuole fusion, although we did not detect a direct interaction of LegC3 with the vacuolar SNARE protein complexes required for fusion. Additionally, LegC3 was incapable of inhibiting a defined synthetic model of vacuolar SNARE-driven membrane fusion, further suggesting that LegC3 does not directly inhibit the activity of vacuolar SNAREs, HOPS complex, or Sec17p/18p during membrane fusion. LegC3 is likely utilized by Legionella to modulate eukaryotic membrane fusion events during pathogenesis. PMID:23437241

HIV-1 Protease in the Fission Yeast Schizosaccharomyces pombe.

PubMed

Benko, Zsigmond; Elder, Robert T; Li, Ge; Liang, Dong; Zhao, Richard Y

2016-01-01

HIV-1 protease (PR) is an essential viral enzyme. Its primary function is to proteolyze the viral Gag-Pol polyprotein for production of viral enzymes and structural proteins and for maturation of infectious viral particles. Increasing evidence suggests that PR cleaves host cellular proteins. However, the nature of PR-host cellular protein interactions is elusive. This study aimed to develop a fission yeast (Schizosaccharomyces pombe) model system and to examine the possible interaction of HIV-1 PR with cellular proteins and its potential impact on cell proliferation and viability. A fission yeast strain RE294 was created that carried a single integrated copy of the PR gene in its chromosome. The PR gene was expressed using an inducible nmt1 promoter so that PR-specific effects could be measured. HIV-1 PR from this system cleaved the same indigenous viral p6/MA protein substrate as it does in natural HIV-1 infections. HIV-1 PR expression in fission yeast cells prevented cell proliferation and induced cellular oxidative stress and changes in mitochondrial morphology that led to cell death. Both these PR activities can be prevented by a PR-specific enzymatic inhibitor, indinavir, suggesting that PR-mediated proteolytic activities and cytotoxic effects resulted from enzymatic activities of HIV-1 PR. Through genome-wide screening, a serine/threonine kinase, Hhp2, was identified that suppresses HIV-1 PR-induced protease cleavage and cell death in fission yeast and in mammalian cells, where it prevented PR-induced apoptosis and cleavage of caspase-3 and caspase-8. This is the first report to show that HIV-1 protease is functional as an enzyme in fission yeast, and that it behaves in a similar manner as it does in HIV-1 infection. HIV-1 PR-induced cell death in fission yeast could potentially be used as an endpoint for mechanistic studies, and this system could be used for developing a high-throughput system for drug screenings.
Chromosomal Aneuploidy Improves the Brewing Characteristics of Sake Yeast.

PubMed

Kadowaki, Masafumi; Fujimaru, Yuki; Taguchi, Seiga; Ferdouse, Jannatul; Sawada, Kazutaka; Kimura, Yuta; Terasawa, Yohei; Agrimi, Gennaro; Anai, Toyoaki; Noguchi, Hideki; Toyoda, Atsushi; Fujiyama, Asao; Akao, Takeshi; Kitagaki, Hiroshi

2017-12-15

The effect of chromosomal aneuploidy on the brewing characteristics of brewery yeasts has not been studied. Here we report that chromosomal aneuploidy in sake brewery yeast ( Saccharomyces cerevisiae ) leads to the development of favorable brewing characteristics. We found that pyruvate-underproducing sake yeast, which produces less off-flavor diacetyl, is aneuploid and trisomic for chromosomes XI and XIV. To confirm that this phenotype is due to aneuploidy, we obtained 45 haploids with various chromosomal additions and investigated their brewing profiles. A greater number of chromosomes correlated with a decrease in pyruvate production. Especially, sake yeast haploids with extra chromosomes in addition to chromosome XI produced less pyruvate than euploids. Mitochondrion-related metabolites and intracellular oxygen species in chromosome XI aneuploids were higher than those in euploids, and this effect was canceled in their "petite" strains, suggesting that an increase in chromosomes upregulated mitochondrial activity and decreased pyruvate levels. These findings suggested that an increase in chromosome number, including chromosome XI, in sake yeast haploids leads to pyruvate underproduction through the augmentation of mitochondrial activity. This is the first report proposing that aneuploidy in brewery yeasts improves their brewing profile. IMPORTANCE Chromosomal aneuploidy has not been evaluated in development of sake brewing yeast strains. This study shows the relationship between chromosomal aneuploidy and brewing characteristics of brewery yeast strains. High concentrations of pyruvate during sake storage give rise to α-acetolactate and, in turn, to high concentrations of diacetyl, which is considered an off-flavor. It was demonstrated that pyruvate-underproducing sake yeast is trisomic for chromosome XI and XIV. Furthermore, sake yeast haploids with extra chromosomes produced reduced levels of pyruvate and showed metabolic processes characteristic of
Chromosomal Aneuploidy Improves the Brewing Characteristics of Sake Yeast

PubMed Central

Kadowaki, Masafumi; Fujimaru, Yuki; Taguchi, Seiga; Ferdouse, Jannatul; Sawada, Kazutaka; Kimura, Yuta; Terasawa, Yohei; Agrimi, Gennaro; Anai, Toyoaki; Noguchi, Hideki; Toyoda, Atsushi; Fujiyama, Asao; Akao, Takeshi

2017-01-01

ABSTRACT The effect of chromosomal aneuploidy on the brewing characteristics of brewery yeasts has not been studied. Here we report that chromosomal aneuploidy in sake brewery yeast (Saccharomyces cerevisiae) leads to the development of favorable brewing characteristics. We found that pyruvate-underproducing sake yeast, which produces less off-flavor diacetyl, is aneuploid and trisomic for chromosomes XI and XIV. To confirm that this phenotype is due to aneuploidy, we obtained 45 haploids with various chromosomal additions and investigated their brewing profiles. A greater number of chromosomes correlated with a decrease in pyruvate production. Especially, sake yeast haploids with extra chromosomes in addition to chromosome XI produced less pyruvate than euploids. Mitochondrion-related metabolites and intracellular oxygen species in chromosome XI aneuploids were higher than those in euploids, and this effect was canceled in their “petite” strains, suggesting that an increase in chromosomes upregulated mitochondrial activity and decreased pyruvate levels. These findings suggested that an increase in chromosome number, including chromosome XI, in sake yeast haploids leads to pyruvate underproduction through the augmentation of mitochondrial activity. This is the first report proposing that aneuploidy in brewery yeasts improves their brewing profile. IMPORTANCE Chromosomal aneuploidy has not been evaluated in development of sake brewing yeast strains. This study shows the relationship between chromosomal aneuploidy and brewing characteristics of brewery yeast strains. High concentrations of pyruvate during sake storage give rise to α-acetolactate and, in turn, to high concentrations of diacetyl, which is considered an off-flavor. It was demonstrated that pyruvate-underproducing sake yeast is trisomic for chromosome XI and XIV. Furthermore, sake yeast haploids with extra chromosomes produced reduced levels of pyruvate and showed metabolic processes characteristic
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)
A rice tonoplastic calcium exchanger, OsCCX2 mediates Ca2+/cation transport in yeast

PubMed Central

Yadav, Akhilesh K.; Shankar, Alka; Jha, Saroj K.; Kanwar, Poonam; Pandey, Amita; Pandey, Girdhar K.

2015-01-01

In plant cell, cations gradient in cellular compartments is maintained by synergistic action of various exchangers, pumps and channels. The Arabidopsis exchanger family members (AtCCX3 and AtCCX5) were previously studied and belong to CaCA (calcium cation exchangers) superfamily while none of the rice CCXs has been functionally characterized for their cation transport activities till date. Rice genome encode four CCXs and only OsCCX2 transcript showed differential expression under abiotic stresses and Ca2+ starvation conditions. The OsCCX2 localized to tonoplast and suppresses the Ca2+ sensitivity of K667 (low affinity Ca2+ uptake deficient) yeast mutant under excess CaCl2 conditions. In contrast to AtCCXs, OsCCX2 expressing K667 yeast cells show tolerance towards excess Na+, Li+, Fe2+, Zn2+ and Co2+ and suggest its ability to transport both mono as well as divalent cations in yeast. Additionally, in contrast to previously characterized AtCCXs, OsCCX2 is unable to complement yeast trk1trk2 double mutant suggesting inability to transport K+ in yeast system. These finding suggest that OsCCX2 having distinct metal transport properties than previously characterized plant CCXs. OsCCX2 can be used as potential candidate for enhancing the abiotic stress tolerance in plants as well as for phytoremediation of heavy metal polluted soil. PMID:26607171
Isolation of oligotrophic yeasts from supraglacial environments of different altitude on the Gulkana Glacier (Alaska).

PubMed

Uetake, Jun; Yoshimura, Yoshitaka; Nagatsuka, Naoko; Kanda, Hiroshi

2012-11-01

Psychrophilic yeasts have been isolated from supra- and subglacial ice at many sites worldwide. To understand the ecology of psychrophilic yeasts on glaciers, we focused on their adaptation to wide range of nutrient concentrations and their distribution with altitude on the Gulkana Glacier in Alaska. We found various culturable psychrophilic yeasts on the ice surfaces of the glacier, and 11 species were isolated with incubation at 4 °C in four different dilutions of agar medium. Some of our isolated species (Rhodotorula psychrophenolica, Rhodotorula aff. psychrophenolica, Rhodotorula glacialis, and Basidiomycota sp. 1) can grow on the low dissolved organic matter (DOC) concentrations medium (7.6 mg L(-1)) which is close to the typical level of supraglacial melt water, suggesting that these species can inhabit in any supraglacial meltwater. Otherwise, most of other species were isolated only from higher DOC concentration medium (183 mg L(-1) -18.3 g L(-1)), suggesting that these are inhabitant around the cryoconite, because DOC concentrations in melted surface-ice contained cryoconite is much higher than in melted water. Similarity of altitudinal distribution between culturable yeast and algal biomass suggests that the ecological role played by the cold-adapted yeasts is as organic matter decomposers and nutrient cyclers in glacier ecosystem. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
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.
Yeast Infection (Vaginal)

MedlinePlus

Yeast infection (vaginal) Overview A vaginal yeast infection is a fungal infection that causes irritation, discharge and intense itchiness ... symptoms Causes The fungus candida causes a vaginal yeast infection. Your vagina naturally contains a balanced mix of yeast, including ...
Promoter-Terminator Gene Loops Affect Alternative 3'-End Processing in Yeast.

PubMed

Lamas-Maceiras, Mónica; Singh, Badri Nath; Hampsey, Michael; Freire-Picos, María A

2016-04-22

Many eukaryotic genes undergo alternative 3'-end poly(A)-site selection producing transcript isoforms with 3'-UTRs of different lengths and post-transcriptional fates. Gene loops are dynamic structures that juxtapose the 3'-ends of genes with their promoters. Several functions have been attributed to looping, including memory of recent transcriptional activity and polarity of transcription initiation. In this study, we investigated the relationship between gene loops and alternative poly(A)-site. Using the KlCYC1 gene of the yeast Kluyveromyces lactis, which includes a single promoter and two poly(A) sites separated by 394 nucleotides, we demonstrate in two yeast species the formation of alternative gene loops (L1 and L2) that juxtapose the KlCYC1 promoter with either proximal or distal 3'-end processing sites, resulting in the synthesis of short and long forms of KlCYC1 mRNA. Furthermore, synthesis of short and long mRNAs and formation of the L1 and L2 loops are growth phase-dependent. Chromatin immunoprecipitation experiments revealed that the Ssu72 RNA polymerase II carboxyl-terminal domain phosphatase, a critical determinant of looping, peaks in early log phase at the proximal poly(A) site, but as growth phase advances, it extends to the distal site. These results define a cause-and-effect relationship between gene loops and alternative poly(A) site selection that responds to different physiological signals manifested by RNA polymerase II carboxyl-terminal domain phosphorylation status. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.
Amino acid substitution equivalent to human chorea-acanthocytosis I2771R in yeast Vps13 protein affects its binding to phosphatidylinositol 3-phosphate

PubMed Central

Rzepnikowska, Weronika; Flis, Krzysztof; Kaminska, Joanna; Grynberg, Marcin; Urbanek, Agnieszka; Ayscough, Kathryn R.

2017-01-01

Abstract The rare human disorder chorea-acanthocytosis (ChAc) is caused by mutations in hVPS13A gene. The hVps13A protein interacts with actin and regulates the level of phosphatidylinositol 4-phosphate (PI4P) in the membranes of neuronal cells. Yeast Vps13 is involved in vacuolar protein transport and, like hVps13A, participates in PI4P metabolism. Vps13 proteins are conserved in eukaryotes, but their molecular function remains unknown. One of the mutations found in ChAc patients causes amino acids substitution I2771R which affects the localization of hVps13A in skeletal muscles. To dissect the mechanism of pathogenesis of I2771R, we created and analyzed a yeast strain carrying the equivalent mutation. Here we show that in yeast, substitution I2749R causes dysfunction of Vps13 protein in endocytosis and vacuolar transport, although the level of the protein is not affected, suggesting loss of function. We also show that Vps13, like hVps13A, influences actin cytoskeleton organization and binds actin in immunoprecipitation experiments. Vps13-I2749R binds actin, but does not function in the actin cytoskeleton organization. Moreover, we show that Vps13 binds phospholipids, especially phosphatidylinositol 3-phosphate (PI3P), via its SHR_BD and APT1 domains. Substitution I2749R attenuates this ability. Finally, the localization of Vps13-GFP is altered when cellular levels of PI3P are decreased indicating its trafficking within the endosomal membrane system. These results suggest that PI3P regulates the functioning of Vps13, both in protein trafficking and actin cytoskeleton organization. Attenuation of PI3P-binding ability in the mutant hVps13A protein may be one of the reasons for its mislocalization and disrupted function in cells of patients suffering from ChAc. PMID:28334785
Comparative genomics of wild type yeast strains unveils important genome diversity

PubMed Central

Carreto, Laura; Eiriz, Maria F; Gomes, Ana C; Pereira, Patrícia M; Schuller, Dorit; Santos, Manuel AS

2008-01-01

Background Genome variability generates phenotypic heterogeneity and is of relevance for adaptation to environmental change, but the extent of such variability in natural populations is still poorly understood. For example, selected Saccharomyces cerevisiae strains are variable at the ploidy level, have gene amplifications, changes in chromosome copy number, and gross chromosomal rearrangements. This suggests that genome plasticity provides important genetic diversity upon which natural selection mechanisms can operate. Results In this study, we have used wild-type S. cerevisiae (yeast) strains to investigate genome variation in natural and artificial environments. We have used comparative genome hybridization on array (aCGH) to characterize the genome variability of 16 yeast strains, of laboratory and commercial origin, isolated from vineyards and wine cellars, and from opportunistic human infections. Interestingly, sub-telomeric instability was associated with the clinical phenotype, while Ty element insertion regions determined genomic differences of natural wine fermentation strains. Copy number depletion of ASP3 and YRF1 genes was found in all wild-type strains. Other gene families involved in transmembrane transport, sugar and alcohol metabolism or drug resistance had copy number changes, which also distinguished wine from clinical isolates. Conclusion We have isolated and genotyped more than 1000 yeast strains from natural environments and carried out an aCGH analysis of 16 strains representative of distinct genotype clusters. Important genomic variability was identified between these strains, in particular in sub-telomeric regions and in Ty-element insertion sites, suggesting that this type of genome variability is the main source of genetic diversity in natural populations of yeast. The data highlights the usefulness of yeast as a model system to unravel intraspecific natural genome diversity and to elucidate how natural selection shapes the yeast genome
A specific role of the yeast mitochondrial carriers MRS3/4p in mitochondrial iron acquisition under iron-limiting conditions.

PubMed

Mühlenhoff, Ulrich; Stadler, Jochen A; Richhardt, Nadine; Seubert, Andreas; Eickhorst, Thomas; Schweyen, Rudolf J; Lill, Roland; Wiesenberger, Gerlinde

2003-10-17

The yeast genes MRS3 and MRS4 encode two members of the mitochondrial carrier family with high sequence similarity. To elucidate their function we utilized genome-wide expression profiling and found that both deletion and overexpression of MRS3/4 lead to up-regulation of several genes of the "iron regulon." We therefore analyzed the two major iron-utilizing processes, heme formation and Fe/S protein biosynthesis in vivo, in organello (intact mitochondria), and in vitro (mitochondrial extracts). Radiolabeling of yeast cells with 55Fe revealed a clear correlation between MRS3/4 expression levels and the efficiency of these biosynthetic reactions indicating a role of the carriers in utilization and/or transport of iron in vivo. Similar effects on both heme formation and Fe/S protein biosynthesis were seen in organello using mitochondria isolated from cells grown under iron-limiting conditions. The correlation between MRS3/4 expression levels and the efficiency of the two iron-utilizing processes was lost upon detergent lysis of mitochondria. As no significant changes in the mitochondrial membrane potential were observed upon overexpression or deletion of MRS3/4, our results suggest that Mrs3/4p carriers are directly involved in mitochondrial iron uptake. Mrs3/4p function in mitochondrial iron transport becomes evident under iron-limiting conditions only, indicating that the two carriers do not represent the sole system for mitochondrial iron acquisition.
Novel endophytic yeast Rhodotorula mucilaginosa strain PTD3 II: production of xylitol and ethanol in the presence of inhibitors.

PubMed

Vajzovic, Azra; Bura, Renata; Kohlmeier, Kevin; Doty, Sharon L

2012-10-01

A systematic study was conducted characterizing the effect of furfural, 5-hydroxymethylfurfural (5-HMF), and acetic acid concentration on the production of xylitol and ethanol by a novel endophytic yeast, Rhodotorula mucilaginosa strain PTD3. The influence of different inhibitor concentrations on the growth and fermentation abilities of PTD3 cultivated in synthetic nutrient media containing 30 g/l xylose or glucose were measured during liquid batch cultures. Concentrations of up to 5 g/l of furfural stimulated production of xylitol to 77 % of theoretical yield (10 % higher compared to the control) by PTD3. Xylitol yields produced by this yeast were not affected in the presence of 5-HMF at concentrations of up to 3 g/l. At higher concentrations of furfural and 5-HMF, xylitol and ethanol yields were negatively affected. The higher the concentration of acetic acid present in a media, the higher the ethanol yield approaching 99 % of theoretical yield (15 % higher compared to the control) was produced by the yeast. At all concentrations of acetic acid tested, xylitol yield was lowered. PTD3 was capable of metabolizing concentrations of 5, 15, and 5 g/l of furfural, 5-HMF, and acetic acid, respectively. This yeast would be a potent candidate for the bioconversion of lignocellulosic sugars to biochemicals given that in the presence of low concentrations of inhibitors, its xylitol and ethanol yields are stimulated, and it is capable of metabolizing pretreatment degradation products.
Associations of Yeasts with Spotted-Wing Drosophila (Drosophila suzukii; Diptera: Drosophilidae) in Cherries and Raspberries

PubMed Central

Hernández, Alejandro; Zalom, Frank G.

2012-01-01

A rich history of investigation documents various Drosophila-yeast mutualisms, suggesting that Drosophila suzukii similarly has an association with a specific yeast species or community. To discover candidate yeast species, yeasts were isolated from larval frass, adult midguts, and fruit hosts of D. suzukii. Terminal restriction fragment length polymorphism (TRFLP) technology and decimal dilution plating were used to identify and determine the relative abundance of yeast species present in fruit juice samples that were either infested with D. suzukii or not infested. Yeasts were less abundant in uninfested than infested samples. A total of 126 independent yeast isolates were cultivated from frass, midguts, and fruit hosts of D. suzukii, representing 28 species of yeasts, with Hanseniaspora uvarum predominating. This suggests an association between D. suzukii and H. uvarum that could be utilized for pest management of the highly pestiferous D. suzukii. PMID:22582060
Low toxicity of HfO2, SiO2, Al2O3 and CeO2 nanoparticles to the yeast, Saccharomyces cerevisiae.

PubMed

García-Saucedo, Citlali; Field, James A; Otero-Gonzalez, Lila; Sierra-Álvarez, Reyes

2011-09-15

Increasing use of nanomaterials necessitates an improved understanding of their potential impact on environment health. This study evaluated the cytotoxicity of nanosized HfO(2), SiO(2), Al(2)O(3) and CeO(2) towards the eukaryotic model organism Saccharomyces cerevisiae, and characterized their state of dispersion in bioassay medium. Nanotoxicity was assessed by monitoring oxygen consumption in batch cultures and by analysis of cell membrane integrity. CeO(2), Al(2)O(3), and HfO(2) nanoparticles were highly unstable in yeast medium and formed micron-sized, settleable agglomerates. A non-toxic polyacrylate dispersant (Dispex A40) was used to improve nanoparticle stability and determine the impact of enhanced dispersion on toxicity. None of the NPs tested without dispersant inhibited O(2) uptake by yeast at concentrations as high as 1000 mg/L. Dispersant supplementation only enhanced the toxicity of CeO(2) (47% at 1000 mg/L). Dispersed SiO(2) and Al(2)O(3) (1000 mg/L) caused cell membrane damage, whereas dispersed HfO(2) and CeO(2) did not cause significant disruption of membrane integrity at the same concentration. These results suggest that the O(2) uptake inhibition observed with dispersed CeO(2) NPs was not due to reduced cell viability. This is the first study evaluating toxicity of nanoscale HfO(2), SiO(2), Al(2)O(3) and CeO(2) to S. cerevisiae. Overall the results obtained demonstrate that these nanomaterials display low or no toxicity to yeast. Copyright © 2011 Elsevier B.V. All rights reserved.
Functional adaptation between yeast actin and its cognate myosin motors.

PubMed

Stark, Benjamin C; Wen, Kuo-Kuang; Allingham, John S; Rubenstein, Peter A; Lord, Matthew

2011-09-02

We employed budding yeast and skeletal muscle actin to examine the contribution of the actin isoform to myosin motor function. While yeast and muscle actin are highly homologous, they exhibit different charge density at their N termini (a proposed myosin-binding interface). Muscle myosin-II actin-activated ATPase activity is significantly higher with muscle versus yeast actin. Whether this reflects inefficiency in the ability of yeast actin to activate myosin is not known. Here we optimized the isolation of two yeast myosins to assess actin function in a homogenous system. Yeast myosin-II (Myo1p) and myosin-V (Myo2p) accommodate the reduced N-terminal charge density of yeast actin, showing greater activity with yeast over muscle actin. Increasing the number of negative charges at the N terminus of yeast actin from two to four (as in muscle) had little effect on yeast myosin activity, while other substitutions of charged residues at the myosin interface of yeast actin reduced activity. Thus, yeast actin functions most effectively with its native myosins, which in part relies on associations mediated by its outer domain. Compared with yeast myosin-II and myosin-V, muscle myosin-II activity was very sensitive to salt. Collectively, our findings suggest differing degrees of reliance on electrostatic interactions during weak actomyosin binding in yeast versus muscle. Our study also highlights the importance of native actin isoforms when considering the function of myosins.
The dynamic three-dimensional organization of the diploid yeast genome

PubMed Central

Kim, Seungsoo; Liachko, Ivan; Brickner, Donna G; Cook, Kate; Noble, William S; Brickner, Jason H; Shendure, Jay; Dunham, Maitreya J

2017-01-01

The budding yeast Saccharomyces cerevisiae is a long-standing model for the three-dimensional organization of eukaryotic genomes. However, even in this well-studied model, it is unclear how homolog pairing in diploids or environmental conditions influence overall genome organization. Here, we performed high-throughput chromosome conformation capture on diverged Saccharomyces hybrid diploids to obtain the first global view of chromosome conformation in diploid yeasts. After controlling for the Rabl-like orientation using a polymer model, we observe significant homolog proximity that increases in saturated culture conditions. Surprisingly, we observe a localized increase in homologous interactions between the HAS1-TDA1 alleles specifically under galactose induction and saturated growth. This pairing is accompanied by relocalization to the nuclear periphery and requires Nup2, suggesting a role for nuclear pore complexes. Together, these results reveal that the diploid yeast genome has a dynamic and complex 3D organization. DOI: http://dx.doi.org/10.7554/eLife.23623.001 PMID:28537556
21 CFR 172.325 - Bakers yeast protein.

Code of Federal Regulations, 2010 CFR

2010-04-01

... harmful microbial toxin. (d) The ingredient is used in food as a nutrient supplement as defined in § 170.3... Special Dietary and Nutritional Additives § 172.325 Bakers yeast protein. Bakers yeast protein may be...
21 CFR 172.325 - Bakers yeast protein.

Code of Federal Regulations, 2012 CFR

2012-04-01

... harmful microbial toxin. (d) The ingredient is used in food as a nutrient supplement as defined in § 170.3... Special Dietary and Nutritional Additives § 172.325 Bakers yeast protein. Bakers yeast protein may be...
21 CFR 172.325 - Bakers yeast protein.

Code of Federal Regulations, 2011 CFR

2011-04-01

... harmful microbial toxin. (d) The ingredient is used in food as a nutrient supplement as defined in § 170.3... Special Dietary and Nutritional Additives § 172.325 Bakers yeast protein. Bakers yeast protein may be...

21 CFR 172.325 - Bakers yeast protein.

Code of Federal Regulations, 2013 CFR

2013-04-01

... harmful microbial toxin. (d) The ingredient is used in food as a nutrient supplement as defined in § 170.3... Special Dietary and Nutritional Additives § 172.325 Bakers yeast protein. Bakers yeast protein may be...
New lager yeast strains generated by interspecific hybridization.

PubMed

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

2015-05-01

The interspecific hybrid Saccharomyces pastorianus is the most commonly used yeast in brewery fermentations worldwide. Here, we generated de novo lager yeast hybrids by mating a domesticated and strongly flocculent Saccharomyces cerevisiae ale strain with the Saccharomyces eubayanus type strain. The hybrids were characterized with respect to the parent strains in a wort fermentation performed at temperatures typical for lager brewing (12 °C). The resulting beers were analysed for sugar and aroma compounds, while the yeasts were tested for their flocculation ability and α-glucoside transport capability. These hybrids inherited beneficial properties from both parent strains (cryotolerance, maltotriose utilization and strong flocculation) and showed apparent hybrid vigour, fermenting faster and producing beer with higher alcohol content (5.6 vs 4.5 % ABV) than the parents. Results suggest that interspecific hybridization is suitable for production of novel non-GM lager yeast strains with unique properties and will help in elucidating the evolutionary history of industrial lager yeast.
S-Adenosyl-L-methionine protects the probiotic yeast, Saccharomyces boulardii, from acid-induced cell death.

PubMed

Cascio, Vincent; Gittings, Daniel; Merloni, Kristen; Hurton, Matthew; Laprade, David; Austriaco, Nicanor

2013-02-13

Saccharomyces boulardii is a probiotic yeast routinely used to prevent and to treat gastrointestinal disorders, including the antibiotic-associated diarrhea caused by Clostridium difficile infections. However, only 1-3% of the yeast administered orally is recovered alive in the feces suggesting that this yeast is unable to survive the acidic environment of the gastrointestinal tract. We provide evidence that suggests that S. boulardii undergoes programmed cell death (PCD) in acidic environments, which is accompanied by the generation of reactive oxygen species and the appearance of caspase-like activity. To better understand the mechanism of cell death at the molecular level, we generated microarray gene expression profiles of S. boulardii cells cultured in an acidic environment. Significantly, functional annotation revealed that the up-regulated genes were significantly over-represented in cell death pathways Finally, we show that S-adenosyl-L-methionine (AdoMet), a commercially available, FDA-approved dietary supplement, enhances the viability of S. boulardii in acidic environments, most likely by preventing programmed cell death. In toto, given the observation that many of the proven health benefits of S. boulardii are dependent on cell viability, our data suggests that taking S. boulardii and AdoMet together may be a more effective treatment for gastrointestinal disorders than taking the probiotic yeast alone.
Volatile sulphur compounds and pathways of L-methionine catabolism in Williopsis yeasts.

PubMed

Tan, Amelia W J; Lee, Pin-Rou; Seow, Yi-Xin; Ong, Peter K C; Liu, Shao-Quan

2012-08-01

Volatile sulphur compounds (VSCs) are important to the food industry due to their high potency and presence in many foods. This study assessed for the first time VSC production and pathways of L: -methionine catabolism in yeasts from the genus Williopsis with a view to understanding VSC formation and their potential flavour impact. Five strains of Williopsis saturnus (var. saturnus, var. subsufficiens, var. suavolens, var. sargentensis and var. mrakii) were screened for VSC production in a synthetic medium supplemented with L: -methionine. A diverse range of VSCs were produced including dimethyl disulphide, dimethyl trisulphide, 3-(methylthio)-1-propanal (methional), 3-(methylthio)-1-propanol (methionol), 3-(methylthio)-1-propene, 3-(methylthio)-1-propyl acetate, 3-(methylthio)-1-propanoic acid (methionic acid) and ethyl 3-(methylthio)-1-propanoate, though the production of these VSCs varied between yeast strains. W. saturnus var. saturnus NCYC22 was selected for further studies due to its relatively high VSC production. VSC production was characterised step-wise with yeast strain NCYC22 in coconut cream at different L: -methionine concentrations (0.00-0.20%) and under various inorganic sulphate (0.00-0.20%) and nitrogen (ammonia) supplementation (0.00-0.20%), respectively. Optimal VSC production was obtained with 0.1% of L: -methionine, while supplementation of sulphate had no significant effect. Nitrogen supplementation showed a dramatic inhibitory effect on VSC production. Based on the production of VSCs, the study suggests that the Ehrlich pathway of L: -methionine catabolism is operative in W. saturnus yeasts and can be manipulated by adjusting certain nutrient parameters to control VSC production.
[Control levels of Sin3 histone deacetylase for spontaneous and UV-induced mutagenesis in yeasts Saccharomyces cerevisiae].

PubMed

Lebovka, I Iu; Kozhina, T N; Fedorova, I V; Peshekhonov, V T; Evstiukhina, T A; Chernenkov, A Iu; Korolev, V G

2014-01-01

SIN3 gene product operates as a repressor for a huge amount of genes in Saccharomyces cerevisiae. Sin3 protein with a mass of about 175 kDa is a member of the RPD3 protein complex with an assessed mass of greater than 2 million Da. It was previously shownthat RPD3 gene mutations influence recombination and repair processes in S. cerevisiae yeasts. We studied the impacts of the sin3 mutation on UV-light sensitivity and UV-induced mutagenesis in budding yeast cells. The deletion ofthe SIN3 gene causes weak UV-sensitivity of mutant budding cells as compared to the wild-type strain. These results show that the sin3 mutation decreases both spontaneous and UV-induced levels of levels. This fact is hypothetically related to themalfunction of ribonucleotide reductase activity regulation, which leads to a decrease in the dNTP pool and the inaccurate error-prone damage bypass postreplication repair pathway, which in turn provokes a reduction in the incidence of mutations.
Effect of temperature on replicative aging of the budding yeast Saccharomyces cerevisiae.

PubMed

Molon, Mateusz; Zadrag-Tecza, Renata

2016-04-01

The use of the budding yeast Saccharomyces cerevisiae in gerontological studies was based on the assumption that the reproduction limit of a single cell (replicative aging) is a consequence of accumulation of a hypothetical universal "senescence factor" within the mother cell. However, some evidence suggests that molecules or structures proposed as the "aging factor", such as rDNA circles, oxidatively damaged proteins (with carbonyl groups) or mitochondria, have little effect on replicative lifespan of yeast cells. Our results also suggest that protein aggregates associated with Hsp104, treated as a marker of yeast aging, do not seem to affect the numeric value of replicative lifespan of yeast. What these results indicate, however, is the need for finding a different way of expressing age and longevity of yeast cells instead of the commonly used number of daughters produced over units of time, as in the case of other organisms. In this paper, we show that the temperature has a stronger influence on the time of life (the total lifespan) than on the reproductive potential of yeast cells.
Effects of yeast and bran on phytate degradation and minerals in rice bread.

PubMed

Kadan, R S; Phillippy, B Q

2007-05-01

Rice bread is a potential alternative to wheat bread for gluten-sensitive individuals. Incorporation of rice bran into bread made from white rice flour adds flavor but also phytic acid, which can reduce the bioavailability of minerals. Breads with varied amounts of defatted bran and yeast were prepared to determine their effects on the phytate and mineral contents of the bread. A completely randomized factorial design was used with bran levels of 3.7%, 7.3%, and 10.5% of the dry ingredients and yeast levels of 1.6%, 3.2%, and 4.7%. Increasing the amount of bran decreased the phytate degradation from 42% at the lowest level of bran to 10% at the highest, and the amount of yeast had no significant effect. The bran contributed substantial amounts of magnesium, iron, and zinc. Breads with the lowest level of bran had phytate-to-zinc molar ratios between 5 and 10, which suggest medium zinc bioavailability. Rice bread is a tasty and nutritious food that is a good dietary source of minerals for people who cannot tolerate wheat bread.
Regulation of transcriptional silencing and chromodomain protein localization at centromeric heterochromatin by histone H3 tyrosine 41 phosphorylation in fission yeast.

PubMed

Ren, Bingbing; Tan, Hwei Ling; Nguyen, Thi Thuy Trang; Sayed, Ahmed Mahmoud Mohammed; Li, Ying; Mok, Yu-Keung; Yang, Henry; Chen, Ee Sin

2018-01-09

Heterochromatin silencing is critical for genomic integrity and cell survival. It is orchestrated by chromodomain (CD)-containing proteins that bind to methylated histone H3 lysine 9 (H3K9me), a hallmark of heterochromatin. Here, we show that phosphorylation of tyrosine 41 (H3Y41p)-a novel histone H3 modification-participates in the regulation of heterochromatin in fission yeast. We show that a loss-of-function mutant of H3Y41 can suppress heterochromatin de-silencing in the centromere and subtelomere repeat regions, suggesting a de-silencing role for H3Y41p on heterochromatin. Furthermore, we show both in vitro and in vivo that H3Y41p differentially regulates two CD-containing proteins without the change in the level of H3K9 methylation: it promotes the binding of Chp1 to histone H3 and the exclusion of Swi6. H3Y41p is preferentially enriched on centromeric heterochromatin during M- to early S phase, which coincides with the localization switch of Swi6/Chp1. The loss-of-function H3Y41 mutant could suppress the hypersensitivity of the RNAi mutants towards hydroxyurea (HU), which arrests replication in S phase. Overall, we describe H3Y41p as a novel histone modification that differentially regulates heterochromatin silencing in fission yeast via the binding of CD-containing proteins. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.
Enumeration and rapid identification of yeasts during extraction processes of extra virgin olive oil in Tuscany.

PubMed

Mari, Eleonora; Guerrini, Simona; Granchi, Lisa; Vincenzini, Massimo

2016-06-01

The aim of this study was to evaluate the occurrence of yeast populations during different olive oil extraction processes, carried out in three consecutive years in Tuscany (Italy), by analysing crushed pastes, kneaded pastes, oil from decanter and pomaces. The results showed yeast concentrations ranging between 10(3) and 10(5) CFU/g or per mL. Seventeen dominant yeast species were identified by random amplified polymorphic DNA with primer M13 and their identification was confirmed by restriction fragments length polymorphism of ribosomal internal transcribed spacer and sequencing rRNA genes. The isolation frequencies of each species in the collected samples pointed out that the occurrence of the various yeast species in olive oil extraction process was dependent not only on the yeasts contaminating the olives but also on the yeasts colonizing the plant for oil extraction. In fact, eleven dominant yeast species were detected from the washed olives, but only three of them were also found in oil samples at significant isolation frequency. On the contrary, the most abundant species in oil samples, Yamadazyma terventina, did not occur in washed olive samples. These findings suggest a phenomenon of contamination of the plant for oil extraction that selects some yeast species that could affect the quality of olive oil.
Yeast-assisted synthesis of polypyrrole: Quantification and influence on the mechanical properties of the cell wall.

PubMed

Andriukonis, Eivydas; Stirke, Arunas; Garbaras, Andrius; Mikoliunaite, Lina; Ramanaviciene, Almira; Remeikis, Vidmantas; Thornton, Barry; Ramanavicius, Arunas

2018-04-01

In this study, the metabolism of yeast cells (Saccharomyces cerevisiae) was utilized for the synthesis of the conducting polymer - polypyrrole (Ppy).Yeast cells were modified in situ by synthesized Ppy. The Ppy was formed in the cell wall by redox-cycling of [Fe(CN) 6 ] 3-/4- , performed by the yeast cells. Fluorescence microscopy, enzymatic digestions, atomic force microscopy and isotope ratio mass spectroscopy were applied to determine both the polymerization reaction itself and the polymer location in yeast cells. Ppy formation resulted in enhanced resistance to lytic enzymes, significant increase of elasticity and alteration of other mechanical cell wall properties evaluated by atomic force microscopy (AFM). The suggested method of polymer synthesis allows the introduction of polypyrrole structures within the cell wall, which is build up from polymers consisting of carbohydrates. This cell wall modification strategy could increase the usefulness of yeast as an alternative energy source in biofuel cells, and in cell based biosensors. Copyright © 2018 Elsevier B.V. All rights reserved.
Characterization of active reverse transcriptase and nucleoprotein complexes of the yeast retrotransposon Ty3 in vitro.

PubMed

Cristofari, G; Gabus, C; Ficheux, D; Bona, M; Le Grice, S F; Darlix, J L

1999-12-17

Human immunodeficiency virus (HIV) and the distantly related yeast Ty3 retrotransposon encode reverse transcriptase (RT) and a nucleic acid-binding protein designated nucleocapsid protein (NCp) with either one or two zinc fingers, required for HIV-1 replication and Ty3 transposition, respectively. In vitro binding of HIV-1 NCp7 to viral 5' RNA and primer tRNA(3)(Lys) catalyzes formation of nucleoprotein complexes resembling the virion nucleocapsid. Nucleocapsid complex formation functions in viral RNA dimerization and tRNA annealing to the primer binding site (PBS). RT is recruited in these nucleoprotein complexes and synthesizes minus-strand cDNA initiated at the PBS. Recent results on yeast Ty3 have shown that the homologous NCp9 promotes annealing of primer tRNA(i)(Met) to a 5'-3' bipartite PBS, allowing RNA:tRNA dimer formation and initiation of cDNA synthesis at the 5' PBS (). To compare specific cDNA synthesis in a retrotransposon and HIV-1, we have established a Ty3 model system comprising Ty3 RNA with the 5'-3' PBS, primer tRNA(i)(Met), NCp9, and for the first time, highly purified Ty3 RT. Here we report that Ty3 RT is as active as retroviral HIV-1 or murine leukemia virus RT using a synthetic template-primer system. Moreover, and in contrast to what was found with retroviral RTs, retrotransposon Ty3 RT was unable to direct cDNA synthesis by self-priming. We also show that Ty3 nucleoprotein complexes were formed in vitro and that the N terminus of NCp9, but not the zinc finger, is required for complex formation, tRNA annealing to the PBS, RNA dimerization, and primer tRNA-directed cDNA synthesis by Ty3 RT. These results indicate that NCp9 chaperones bona fide cDNA synthesis by RT in the yeast Ty3 retrotransposon, as illustrated for NCp7 in HIV-1, reinforcing the notion that Ty3 NCp9 is an ancestor of HIV-1 NCp7.
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)
Identification of the Transcription Factor Znc1p, which Regulates the Yeast-to-Hypha Transition in the Dimorphic Yeast Yarrowia lipolytica

PubMed Central

Martinez-Vazquez, Azul; Gonzalez-Hernandez, Angelica; Domínguez, Ángel; Rachubinski, Richard; Riquelme, Meritxell; Cuellar-Mata, Patricia; Guzman, Juan Carlos Torres

2013-01-01

The dimorphic yeast Yarrowia lipolytica is used as a model to study fungal differentiation because it grows as yeast-like cells or forms hyphal cells in response to changes in environmental conditions. Here, we report the isolation and characterization of a gene, ZNC1, involved in the dimorphic transition in Y. lipolytica. The ZNC1 gene encodes a 782 amino acid protein that contains a Zn(II)2C6 fungal-type zinc finger DNA-binding domain and a leucine zipper domain. ZNC1 transcription is elevated during yeast growth and decreases during the formation of mycelium. Cells in which ZNC1 has been deleted show increased hyphal cell formation. Znc1p-GFP localizes to the nucleus, but mutations within the leucine zipper domain of Znc1p, and to a lesser extent within the Zn(II)2C6 domain, result in a mislocalization of Znc1p to the cytoplasm. Microarrays comparing gene expression between znc1::URA3 and wild-type cells during both exponential growth and the induction of the yeast-to-hypha transition revealed 1,214 genes whose expression was changed by 2-fold or more under at least one of the conditions analyzed. Our results suggest that Znc1p acts as a transcription factor repressing hyphal cell formation and functions as part of a complex network regulating mycelial growth in Y. lipolytica. PMID:23826133
Binding of insertion/deletion DNA mismatches by the heterodimer of yeast mismatch repair proteins MSH2 and MSH3.

PubMed

Habraken, Y; Sung, P; Prakash, L; Prakash, S

1996-09-01

DNA-mismatch repair removes mismatches from the newly replicated DNA strand. In humans, mutations in the mismatch repair genes hMSH2, hMLH1, hPMS1 and hPMS2 result in hereditary non-polyposis colorectal cancer (HNPCC) [1-8]. The hMSH2 (MSH for MutS homologue) protein forms a complex with a 160 kDa protein, and this heterodimer, hMutSalpha, has high affinity for a G/T mismatch [9,10]. Cell lines in which the 160 kDa subunit of hMutSalpha is mutated are specifically defective in the repair of base-base and single-nucleotide insertion/deletion mismatches [9,11]. Genetic studies in S. cerevisiae have suggested that MSH2 functions with either MSH3 or MSH6 in mismatch repair, and, in the absence of the latter two genes, MSH2 is inactive [12,13]. MSH6 encodes the yeast counterpart of the 160 kDa subunit of hMutSalpha [12,13]. As in humans, yeast MSH6 forms a complex with MSH2, and the MSH2-MSH6 heterodimer binds a G/T mismatch [14]. Here, we find that MSH2 and MSH3 form another stable heterodimer, and we purify this heterodimer to near homogeneity. We show that MSH2-MSH3 has low affinity for a G/T mismatch but binds to insertion/deletion mismatches with high specificity, unlike MSH2-MSH6.
Synthesis of polypyrrole within the cell wall of yeast by redox-cycling of [Fe(CN)6](3-)/[Fe(CN)6](4-).

PubMed

Ramanavicius, Arunas; Andriukonis, Eivydas; Stirke, Arunas; Mikoliunaite, Lina; Balevicius, Zigmas; Ramanaviciene, Almira

2016-02-01

Yeast cells are often used as a model system in various experiments. Moreover, due to their high metabolic activity, yeast cells have a potential to be applied as elements in the design of biofuel cells and biosensors. However a wider application of yeast cells in electrochemical systems is limited due to high electric resistance of their cell wall. In order to reduce this problem we have polymerized conducting polymer polypyrrole (Ppy) directly in the cell wall and/or within periplasmic membrane. In this research the formation of Ppy was induced by [Fe(CN)6](3-)ions, which were generated from K4[Fe(CN)6], which was initially added to polymerization solution. The redox process was catalyzed by oxido-reductases, which are present in the plasma membrane of yeast cells. The formation of Ppy was confirmed by spectrophotometry and atomic force microscopy. It was confirmed that the conducting polymer polypyrrole was formed within periplasmic space and/or within the cell wall of yeast cells, which were incubated in solution containing pyrrole, glucose and [Fe(CN)6](4-). After 24h drying at room temperature we have observed that Ppy-modified yeast cell walls retained their initial spherical form. In contrast to Ppy-modified cells, the walls of unmodified yeast have wrinkled after 24h drying. The viability of yeast cells in the presence of different pyrrole concentrations has been evaluated. Copyright © 2015 Elsevier Inc. All rights reserved.
Prions in Yeast

PubMed Central

Liebman, Susan W.; Chernoff, Yury O.

2012-01-01

The concept of a prion as an infectious self-propagating protein isoform was initially proposed to explain certain mammalian diseases. It is now clear that yeast also has heritable elements transmitted via protein. Indeed, the “protein only” model of prion transmission was first proven using a yeast prion. Typically, known prions are ordered cross-β aggregates (amyloids). Recently, there has been an explosion in the number of recognized prions in yeast. Yeast continues to lead the way in understanding cellular control of prion propagation, prion structure, mechanisms of de novo prion formation, specificity of prion transmission, and the biological roles of prions. This review summarizes what has been learned from yeast prions. PMID:22879407
The relationship between salivary histatin levels and oral yeast carriage.

PubMed

Jainkittivong, A; Johnson, D A; Yeh, C K

1998-06-01

Candida species are common commensal inhabitants of the oral cavity. Human saliva contains antifungal proteins called histatins. We tested the hypothesis that oral yeast status is related to salivary histatin levels. Thirty subjects were divided into two groups based on the presence (n = 15) or absence (n = 15) of yeast on oral mucosa surfaces. Unstimulated and stimulated submandibular and sublingual and parotid saliva was collected from each subject. Salivary flow rates were measured and histatin concentrations were determined in the stimulated saliva samples. The yeast colony positive group showed lower median unstimulated parotid saliva flow rates as well as lower median concentrations of total histatins in submandibular and sublingual saliva. There was a negative correlation between yeast colony-forming units and unstimulated parotid saliva flow rates and between yeast colony-forming units and submandibular and sublingual saliva histatin concentration and secretion. The results suggest that oral yeast status may be influenced by unstimulated parotid saliva flow rates and by submandibular and sublingual histatin concentration and secretion.
Unique phagocytic properties of hemocytes of Pacific oyster Crassostrea gigas against yeast and yeast cell-wall derivatives.

PubMed

Takahashi, Keisuke G; Izumi-Nakajima, Nakako; Mori, Katsuyoshi

2017-11-01

For a marine bivalve mollusk such as Pacific oyster Crassostrea gigas, the elimination of foreign particles via hemocyte phagocytosis plays an important role in host defense mechanisms. The hemocytes of C. gigas have a high phagocytic ability for baker's yeast (Saccharomyces cerevisiae) and its cell-wall product zymosan. C. gigas hemocytes might phagocytose yeast cells after binding to polysaccharides on the cell-wall surface, but it is unknown how and what kinds of polysaccharide molecules are recognized. We conducted experiments to determine differences in the phagocytic ability of C. gigas hemocytes against heat-killed yeast (HK yeast), zymosan and zymocel, which are similarly sized and shaped but differ in the polysaccharide composition of their particle surface. We found that both the agranulocytes and granulocytes exerted strong phagocytic ability on all tested particles. The phagocytic index (PI) of granulocytes for zymosan was 9.4 ± 1.7, which significantly differed with that for HK yeast and zymocel (P < 0.05). To evaluate the PI for the three types of particles, and especially to understand the outcome of the much higher PI for zymosan, PI was gauged in increments of 5 (1-5, 6-10, 11-15, and ≥16), and the phagocytic frequencies were compared according to these increments. The results show that a markedly high PI of ≥16 was exhibited by 18.1% of granulocytes for zymosan, significantly higher than 1.7% and 3.9% shown for HK yeast and zymocel, respectively (P < 0.05). These findings indicate that the relatively high PI for zymosan could not be attributed to a situation wherein all phagocytic hemocytes shared a high mean PI, but rather to the ability of some hemocytes to phagocytose a larger portion of zymosan. To determine whether the phagocytosis of these respective particles depended on the recognition of specific polysaccharide receptors on the hemocyte surface, C. gigas hemocytes were pretreated with soluble α-mannan or β-laminarin and
S-Adenosyl-L-Methionine protects the probiotic yeast, Saccharomyces boulardii, from acid-induced cell death

PubMed Central

2013-01-01

Background Saccharomyces boulardii is a probiotic yeast routinely used to prevent and to treat gastrointestinal disorders, including the antibiotic-associated diarrhea caused by Clostridium difficile infections. However, only 1-3% of the yeast administered orally is recovered alive in the feces suggesting that this yeast is unable to survive the acidic environment of the gastrointestinal tract. Results We provide evidence that suggests that S. boulardii undergoes programmed cell death (PCD) in acidic environments, which is accompanied by the generation of reactive oxygen species and the appearance of caspase-like activity. To better understand the mechanism of cell death at the molecular level, we generated microarray gene expression profiles of S. boulardii cells cultured in an acidic environment. Significantly, functional annotation revealed that the up-regulated genes were significantly over-represented in cell death pathways Finally, we show that S-adenosyl-L-methionine (AdoMet), a commercially available, FDA-approved dietary supplement, enhances the viability of S. boulardii in acidic environments, most likely by preventing programmed cell death. Conclusions In toto, given the observation that many of the proven health benefits of S. boulardii are dependent on cell viability, our data suggests that taking S. boulardii and AdoMet together may be a more effective treatment for gastrointestinal disorders than taking the probiotic yeast alone. PMID:23402325
Screening the yeast genome for energetic metabolism pathways involved in a phenotypic response to the anti-cancer agent 3-bromopyruvate.

PubMed

Lis, Paweł; Jurkiewicz, Paweł; Cal-Bąkowska, Magdalena; Ko, Young H; Pedersen, Peter L; Goffeau, Andre; Ułaszewski, Stanisław

2016-03-01

In this study the detailed characteristic of the anti-cancer agent 3-bromopyruvate (3-BP) activity in the yeast Saccharomyces cerevisiae model is described, with the emphasis on its influence on energetic metabolism of the cell. It shows that 3-BP toxicity in yeast is strain-dependent and influenced by the glucose-repression system. Its toxic effect is mainly due to the rapid depletion of intracellular ATP. Moreover, lack of the Whi2p phosphatase results in strongly increased sensitivity of yeast cells to 3-BP, possibly due to the non-functional system of mitophagy of damaged mitochondria through the Ras-cAMP-PKA pathway. Single deletions of genes encoding glycolytic enzymes, the TCA cycle enzymes and mitochondrial carriers result in multiple effects after 3-BP treatment. However, it can be concluded that activity of the pentose phosphate pathway is necessary to prevent the toxicity of 3-BP, probably due to the fact that large amounts of NADPH are produced by this pathway, ensuring the reducing force needed for glutathione reduction, crucial to cope with the oxidative stress. Moreover, single deletions of genes encoding the TCA cycle enzymes and mitochondrial carriers generally cause sensitivity to 3-BP, while totally inactive mitochondrial respiration in the rho0 mutant resulted in increased resistance to 3-BP.

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.
Freeze-drying of yeast cultures.

PubMed

Bond, Chris

2007-01-01

A method is described that allows yeast species to be stored using a variation on the standard freeze-drying method, which employs evaporative cooling in a two-stage process. Yeast cultures are placed in glass ampoules after having been mixed with a lyoprotectant. Primary drying is carried out using a centrifuge head connected to a standard freeze-dryer. Once the centrifuge head is running, air is removed and evaporated liquid is captured in the freeze-dryer. Centrifugation continues for 15 min and primary drying for a further 3 h. The ampoules are constricted using a glass blowing torch. They are then placed on the freeze-dryer manifold for secondary drying under vacuum overnight, using phosphorus pentoxide as a desiccant. The ampoules are sealed and removed from the manifold by melting the constricted section. Although the process causes an initial large drop in viability, further losses after storage are minimal. Yeast strains have remained viable for more than 30 yr when stored using this method and sufficient cells are recovered to produce new working stocks. Although survival rates are strain specific, nearly all National Collection of Yeast Cultures strains covering most yeast genera, have been successfully stored with little or no detectable change in strain characteristics.
The ecology of insect-yeast relationships and its relevance to human industry.

PubMed

Madden, Anne A; Epps, Mary Jane; Fukami, Tadashi; Irwin, Rebecca E; Sheppard, John; Sorger, D Magdalena; Dunn, Robert R

2018-03-28

Many species of yeast are integral to human society. They produce many of our foods, beverages and industrial chemicals, challenge us as pathogens, and provide models for the study of our own biology. However, few species are regularly studied and much of their ecology remains unclear, hindering the development of knowledge that is needed to improve the relationships between humans and yeasts. There is increasing evidence that insects are an essential component of ascomycetous yeast ecology. We propose a 'dispersal-encounter hypothesis' whereby yeasts are dispersed by insects between ephemeral, spatially disparate sugar resources, and insects, in turn, obtain the benefits of an honest signal from yeasts for the sugar resources. We review the relationship between yeasts and insects through three main examples: social wasps, social bees and beetles, with some additional examples from fruit flies. Ultimately, we suggest that over the next decades, consideration of these ecological and evolutionary relationships between insects and yeasts will allow prediction of where new yeast diversity is most likely to be discovered, particularly yeasts with traits of interest to human industry. © 2018 The Author(s).
The ecology of insect–yeast relationships and its relevance to human industry

PubMed Central

Epps, Mary Jane; Sheppard, John; Sorger, D. Magdalena; Dunn, Robert R.

2018-01-01

Many species of yeast are integral to human society. They produce many of our foods, beverages and industrial chemicals, challenge us as pathogens, and provide models for the study of our own biology. However, few species are regularly studied and much of their ecology remains unclear, hindering the development of knowledge that is needed to improve the relationships between humans and yeasts. There is increasing evidence that insects are an essential component of ascomycetous yeast ecology. We propose a ‘dispersal–encounter hypothesis' whereby yeasts are dispersed by insects between ephemeral, spatially disparate sugar resources, and insects, in turn, obtain the benefits of an honest signal from yeasts for the sugar resources. We review the relationship between yeasts and insects through three main examples: social wasps, social bees and beetles, with some additional examples from fruit flies. Ultimately, we suggest that over the next decades, consideration of these ecological and evolutionary relationships between insects and yeasts will allow prediction of where new yeast diversity is most likely to be discovered, particularly yeasts with traits of interest to human industry. PMID:29563264
Novel insights into the architecture and protein interaction network of yeast eIF3.

PubMed

Khoshnevis, Sohail; Hauer, Florian; Milón, Pohl; Stark, Holger; Ficner, Ralf

2012-12-01

Translation initiation in eukaryotes is a multistep process requiring the orchestrated interaction of several eukaryotic initiation factors (eIFs). The largest of these factors, eIF3, forms the scaffold for other initiation factors, promoting their binding to the 40S ribosomal subunit. Biochemical and structural studies on eIF3 need highly pure eIF3. However, natively purified eIF3 comprise complexes containing other proteins such as eIF5. Therefore we have established in vitro reconstitution protocols for Saccharomyces cerevisiae eIF3 using its five recombinantly expressed and purified subunits. This reconstituted eIF3 complex (eIF3(rec)) exhibits the same size and activity as the natively purified eIF3 (eIF3(nat)). The homogeneity and stoichiometry of eIF3(rec) and eIF3(nat) were confirmed by analytical size exclusion chromatography, mass spectrometry, and multi-angle light scattering, demonstrating the presence of one copy of each subunit in the eIF3 complex. The reconstituted and native eIF3 complexes were compared by single-particle electron microscopy showing a high degree of structural conservation. The interaction network between eIF3 proteins was studied by means of limited proteolysis, analytical size exclusion chromatography, in vitro binding assays, and isothermal titration calorimetry, unveiling distinct protein domains and subcomplexes that are critical for the integrity of the protein network in yeast eIF3. Taken together, the data presented here provide a novel procedure to obtain highly pure yeast eIF3, suitable for biochemical and structural analysis, in addition to a detailed picture of the network of protein interactions within this complex.
Yeast for virus research

PubMed Central

Zhao, Richard Yuqi

2017-01-01

Budding yeast (Saccharomyces cerevisiae) and fission yeast (Schizosaccharomyces pombe) are two popular model organisms for virus research. They are natural hosts for viruses as they carry their own indigenous viruses. Both yeasts have been used for studies of plant, animal and human viruses. Many positive sense (+) RNA viruses and some DNA viruses replicate with various levels in yeasts, thus allowing study of those viral activities during viral life cycle. Yeasts are single cell eukaryotic organisms. Hence, many of the fundamental cellular functions such as cell cycle regulation or programed cell death are highly conserved from yeasts to higher eukaryotes. Therefore, they are particularly suited to study the impact of those viral activities on related cellular activities during virus-host interactions. Yeasts present many unique advantages in virus research over high eukaryotes. Yeast cells are easy to maintain in the laboratory with relative short doubling time. They are non-biohazardous, genetically amendable with small genomes that permit genome-wide analysis of virologic and cellular functions. In this review, similarities and differences of these two yeasts are described. Studies of virologic activities such as viral translation, viral replication and genome-wide study of virus-cell interactions in yeasts are highlighted. Impacts of viral proteins on basic cellular functions such as cell cycle regulation and programed cell death are discussed. Potential applications of using yeasts as hosts to carry out functional analysis of small viral genome and to develop high throughput drug screening platform for the discovery of antiviral drugs are presented. PMID:29082230
L-arabinose fermenting yeast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Min; Singh, Arjun; Suominen, Pirkko

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.
L-arabinose fermenting yeast

DOEpatents

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.
Yeast heterochromatin regulators Sir2 and Sir3 act directly at euchromatic DNA replication origins.

PubMed

Hoggard, Timothy A; Chang, FuJung; Perry, Kelsey Rae; Subramanian, Sandya; Kenworthy, Jessica; Chueng, Julie; Shor, Erika; Hyland, Edel M; Boeke, Jef D; Weinreich, Michael; Fox, Catherine A

2018-05-01

Most active DNA replication origins are found within euchromatin, while origins within heterochromatin are often inactive or inhibited. In yeast, origin activity within heterochromatin is negatively controlled by the histone H4K16 deacetylase, Sir2, and at some heterochromatic loci also by the nucleosome binding protein, Sir3. The prevailing view has been that direct functions of Sir2 and Sir3 are confined to heterochromatin. However, growth defects in yeast mutants compromised for loading the MCM helicase, such as cdc6-4, are suppressed by deletion of either SIR2 or SIR3. While these and other observations indicate that SIR2,3 can have a negative impact on at least some euchromatic origins, the genomic scale of this effect was unknown. It was also unknown whether this suppression resulted from direct functions of Sir2,3 within euchromatin, or was an indirect effect of their previously established roles within heterochromatin. Using MCM ChIP-Seq, we show that a SIR2 deletion rescued MCM complex loading at ~80% of euchromatic origins in cdc6-4 cells. Therefore, Sir2 exhibited a pervasive effect at the majority of euchromatic origins. Using MNase-H4K16ac ChIP-Seq, we show that origin-adjacent nucleosomes were depleted for H4K16 acetylation in a SIR2-dependent manner in wild type (i.e. CDC6) cells. In addition, we present evidence that both Sir2 and Sir3 bound to nucleosomes adjacent to euchromatic origins. The relative levels of each of these molecular hallmarks of yeast heterochromatin-SIR2-dependent H4K16 hypoacetylation, Sir2, and Sir3 -correlated with how strongly a SIR2 deletion suppressed the MCM loading defect in cdc6-4 cells. Finally, a screen for histone H3 and H4 mutants that could suppress the cdc6-4 growth defect identified amino acids that map to a surface of the nucleosome important for Sir3 binding. We conclude that heterochromatin proteins directly modify the local chromatin environment of euchromatic DNA replication origins.
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
Yeast surface displaying glucose oxidase as whole-cell biocatalyst: construction, characterization, and its electrochemical glucose sensing application.

PubMed

Wang, Hongwei; Lang, Qiaolin; Li, Liang; Liang, Bo; Tang, Xiangjiang; Kong, Lingrang; Mascini, Marco; Liu, Aihua

2013-06-18

The display of glucose oxidase (GOx) on yeast cell surface using a-agglutinin as an anchor motif was successfully developed. Both the immunochemical analysis and enzymatic assay showed that active GOx was efficiently expressed and translocated on the cell surface. Compared with conventional GOx, the yeast cell surface that displayed GOx (GOx-yeast) demonstrated excellent enzyme properties, such as good stability within a wide pH range (pH 3.5-11.5), good thermostability (retaining over 94.8% enzyme activity at 52 °C and 84.2% enzyme activity at 56 °C), and high d-glucose specificity. In addition, direct electrochemistry was achieved at a GOx-yeast/multiwalled-carbon-nanotube modified electrode, suggesting that the host cell of yeast did not have any adverse effect on the electrocatalytic property of the recombinant GOx. Thus, a novel electrochemical glucose biosensor based on this GOx-yeast was developed. The as-prepared biosensor was linear with the concentration of d-glucose within the range of 0.1-14 mM and a low detection limit of 0.05 mM (signal-to-noise ratio of S/N = 3). Moreover, the as-prepared biosensor is stable, specific, reproducible, simple, and cost-effective, which can be applicable for real sample detection. The proposed strategy to construct robust GOx-yeast may be applied to explore other oxidase-displaying-system-based whole-cell biocatalysts, which can find broad potential application in biosensors, bioenergy, and industrial catalysis.
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 with...
Brewing characteristics of haploid strains isolated from sake yeast Kyokai No. 7.

PubMed

Katou, Taku; Kitagaki, Hiroshi; Akao, Takeshi; Shimoi, Hitoshi

2008-11-01

Sake yeast exhibit various characteristics that make them more suitable for sake brewing compared to other yeast strains. Since sake yeast strains are Saccharomyces cerevisiae heterothallic diploid strains, it is likely that they have heterozygous alleles on homologous chromosomes (heterozygosity) due to spontaneous mutations. If this is the case, segregation of phenotypic traits in haploid strains after sporulation and concomitant meiosis of sake yeast strains would be expected to occur. To examine this hypothesis, we isolated 100 haploid strains from Kyokai No. 7 (K7), a typical sake yeast strain in Japan, and compared their brewing characteristics in small-scale sake-brewing tests. Analyses of the resultant sake samples showed a smooth and continuous distribution of analytical values for brewing characteristics, suggesting that K7 has multiple heterozygosities that affect brewing characteristics and that these heterozygous alleles do segregate after sporulation. Correlation and principal component analyses suggested that the analytical parameters could be classified into two groups, indicating fermentation ability and sake flavour. (c) 2008 John Wiley & Sons, Ltd.
Screening the yeast genome for energetic metabolism pathways involved in a phenotypic response to the anti-cancer agent 3-bromopyruvate

PubMed Central

Lis, Paweł; Jurkiewicz, Paweł; Cal-Bąkowska, Magdalena; Ko, Young H.; Pedersen, Peter L.; Goffeau, Andre; Ułaszewski, Stanisław

2016-01-01

In this study the detailed characteristic of the anti-cancer agent 3-bromopyruvate (3-BP) activity in the yeast Saccharomyces cerevisiae model is described, with the emphasis on its influence on energetic metabolism of the cell. It shows that 3-BP toxicity in yeast is strain-dependent and influenced by the glucose-repression system. Its toxic effect is mainly due to the rapid depletion of intracellular ATP. Moreover, lack of the Whi2p phosphatase results in strongly increased sensitivity of yeast cells to 3-BP, possibly due to the non-functional system of mitophagy of damaged mitochondria through the Ras-cAMP-PKA pathway. Single deletions of genes encoding glycolytic enzymes, the TCA cycle enzymes and mitochondrial carriers result in multiple effects after 3-BP treatment. However, it can be concluded that activity of the pentose phosphate pathway is necessary to prevent the toxicity of 3-BP, probably due to the fact that large amounts of NADPH are produced by this pathway, ensuring the reducing force needed for glutathione reduction, crucial to cope with the oxidative stress. Moreover, single deletions of genes encoding the TCA cycle enzymes and mitochondrial carriers generally cause sensitivity to 3-BP, while totally inactive mitochondrial respiration in the rho0 mutant resulted in increased resistance to 3-BP. PMID:26862728
In vitro studies on the translocation of acid phosphatase into the endoplasmic reticulum of the yeast Saccharomyces cerevisiae.

PubMed

Krebs, H O; Hoffschulte, H K; Müller, M

1989-05-01

We demonstrate here the in vitro translocation of yeast acid phosphatase into rough endoplasmic reticulum. The precursor of the repressible acid phosphatase from Saccharomyces cerevisiae encoded by the PHO5 gene, was synthesized in a yeast lysate programmed with in vitro transcribed PHO5 mRNA. In the presence of yeast rough microsomes up to 16% of the acid phosphatase synthesized was found to be translocated into the microsomes, as judged by proteinase resistance, and fully core-glycosylated. The translocation efficiency however, decreased to 3% if yeast rough microsomes were added after synthesis of acid phosphatase had been terminated. When a wheat-germ extract was used for in vitro synthesis, the precursor of acid phosphatase was translocated into canine pancreatic rough microsomes and thereby core-glycosylated in a signal-recognition-particle-dependent manner. Replacing canine with yeast rough microsomes in the wheat-germ translation system, however, resulted in a significant decrease in the ability to translocate and glycosylate the precursor. Translocation and glycosylation were partially restored by a high-salt extract prepared from yeast ribosomes. The results presented here suggest that yeast-specific factors are needed to translocate and glycosylate acid phosphatase efficiently in vitro.
Nectar yeasts warm the flowers of a winter-blooming plant

PubMed Central

Herrera, Carlos M.; Pozo, María I.

2010-01-01

Yeasts are ubiquitous in terrestrial and aquatic microbiota, yet their ecological functionality remains relatively unexplored in comparison with other micro-organisms. This paper formulates and tests the novel hypothesis that heat produced by the sugar catabolism of yeast populations inhabiting floral nectar can increase the temperature of floral nectar and, more generally, modify the within-flower thermal microenvironment. Two field experiments were designed to test this hypothesis for the winter-blooming herb Helleborus foetidus (Ranunculaceae). In experiment 1, the effect of yeasts on the within-flower thermal environment was tested by excluding them from flowers, while in experiment 2 the test involved artificial inoculation of virgin flowers with yeasts. Nectary temperature (Tnect), within-flower air temperature (Tflow) and external air temperature (Tair) were measured on experimental and control flowers in both experiments. Experimental exclusion of yeasts from the nectaries significantly reduced, and experimental addition of yeasts significantly increased, the temperature excess of nectaries (ΔTnect = Tnect − Tair) and the air space inside flowers in relation to the air just outside the flowers. In non-experimental flowers exposed to natural pollinator visitation, ΔTnect was linearly related to log yeast cell density in nectar, and reached +6°C in nectaries with the densest yeast populations. The warming effect of nectar-dwelling yeasts documented in this study suggests novel ecological mechanisms potentially linking nectarivorous microbes with winter-blooming plants and their insect pollinators. PMID:20147331
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.
Identification and assessment of kefir yeast potential for sugar/ethanol-resistance

PubMed Central

Miguel, M.G.C.P.; Cardoso, P.G.; Magalhães-Guedes, K.T.; Schwan, R.F.

2013-01-01

Biochemical and molecular analysis was used for identification of different kefir yeasts species from Brazil, Canada and the United States of America. The sugar/ethanol-resistant activity of the yeasts was evaluated. Saccharomyces cerevisiae and Kluyveromyces marxianus had the highest growth rates, suggesting biotechnological applications possible for these strains. PMID:24159292
Enhancement of MSH2-MSH3-mediated mismatch recognition by the yeast MLH1-PMS1 complex.

PubMed

Habraken, Y; Sung, P; Prakash, L; Prakash, S

1997-10-01

DNA mismatch repair has a key role in maintaining genomic stability. Defects in mismatch repair cause elevated spontaneous mutation rates and increased instability of simple repetitive sequences, while mutations in human mismatch repair genes result in hereditary nonpolyposis colorectal cancers. Mismatch recognition represents the first critical step of mismatch repair. Genetic and biochemical studies in yeast and humans have indicated a requirement for MSH2-MSH3 and MSH2-MSH6 heterodimers in mismatch recognition. These complexes have, to some extent, overlapping mismatch binding specificities. MLH1 and PMS1 are the other essential components of mismatch repair, but how they function in this process is not known. We have purified the yeast MLH1-PMS1 heterodimer to near homogeneity, and examined its effect on MSH2-MSH3 binding to DNA mismatches. By itself, the MLH1-PMS1 complex shows no affinity for mismatched DNA, but it greatly enhances the mismatch binding ability of MSH2-MSH3.
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)

Conversion of yellow wine lees into high-protein yeast culture by solid-state fermentation.

PubMed

Hu, Yuanliang; Pan, Lina; Dun, Yaohao; Peng, Nan; Liang, Yunxiang; Zhao, Shumiao

2014-09-03

This study is focussed on the possibility of producing a yeast culture with yellow wine lees as a substrate by solid-state fermentation (SSF). Results showed that a yeast count of 1.58 × 10 9 CFU/g was achieved by signal factor and orthogonal experiments. After fermentation, the starch content in the yeast culture reduced from 32.2% ± 0.5% to 7.5% ± 0.2%, and the contents of crude protein and peptide increased from 36.1% ± 0.8% to 48.0% ± 1.0% and 3.9% ± 0.2% to 7.2% ± 0.4%, respectively. Additionally, large amounts of short peptides and free amino acids were detected by fast protein liquid chromatography (FPLC). These results suggest that yellow wine lees are a suitable substrate for the production of yeast cultures. It can serve as a growth-promoting factor and help reduce the shortage of protein feed in the animal industry. This research provides a potential way for the utilization of agro-industrial residues.
Conversion of yellow wine lees into high-protein yeast culture by solid-state fermentation

PubMed Central

Hu, Yuanliang; Pan, Lina; Dun, Yaohao; Peng, Nan; Liang, Yunxiang; Zhao, Shumiao

2014-01-01

This study is focussed on the possibility of producing a yeast culture with yellow wine lees as a substrate by solid-state fermentation (SSF). Results showed that a yeast count of 1.58 × 109 CFU/g was achieved by signal factor and orthogonal experiments. After fermentation, the starch content in the yeast culture reduced from 32.2% ± 0.5% to 7.5% ± 0.2%, and the contents of crude protein and peptide increased from 36.1% ± 0.8% to 48.0% ± 1.0% and 3.9% ± 0.2% to 7.2% ± 0.4%, respectively. Additionally, large amounts of short peptides and free amino acids were detected by fast protein liquid chromatography (FPLC). These results suggest that yellow wine lees are a suitable substrate for the production of yeast cultures. It can serve as a growth-promoting factor and help reduce the shortage of protein feed in the animal industry. This research provides a potential way for the utilization of agro-industrial residues. PMID:26019568
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.
Further studies on the quaternary structure of yeast casein kinase II.

PubMed

Szyszka, R; Lopaczyński, W; Gałasiński, W; Grankowski, N; Gasior, E

1986-01-01

Casein kinase type II were isolated by the same procedure, from rat liver, human placenta, Querin carcinoma and yeast, and characterized. The mammalian enzymes were composed of three subunits alpha, alpha' and beta, whereas yeast kinase was composed of two subunits alpha and alpha'. It was shown that the catalytic activity, substrate and phosphate donor specificity, sensitivity to heparin and spermine were the same for all the kinases tested. The results give additional support to the suggestion [1] that the beta subunit is not required for optimal activity and specificity of yeast casein kinase II. The quaternary structure of the yeast enzyme of a molecular weight of approximately 150 000 is proposed as alpha2 alpha'2.
Prm3p is a pheromone-induced peripheral nuclear envelope protein required for yeast nuclear fusion.

PubMed

Shen, Shu; Tobery, Cynthia E; Rose, Mark D

2009-05-01

Nuclear membrane fusion is the last step in the mating pathway of the yeast Saccharomyces cerevisiae. We adapted a bioinformatics approach to identify putative pheromone-induced membrane proteins potentially required for nuclear membrane fusion. One protein, Prm3p, was found to be required for nuclear membrane fusion; disruption of PRM3 caused a strong bilateral defect, in which nuclear congression was completed but fusion did not occur. Prm3p was localized to the nuclear envelope in pheromone-responding cells, with significant colocalization with the spindle pole body in zygotes. A previous report, using a truncated protein, claimed that Prm3p is localized to the inner nuclear envelope. Based on biochemistry, immunoelectron microscopy and live cell microscopy, we find that functional Prm3p is a peripheral membrane protein exposed on the cytoplasmic face of the outer nuclear envelope. In support of this, mutations in a putative nuclear localization sequence had no effect on full-length protein function or localization. In contrast, point mutations and deletions in the highly conserved hydrophobic carboxy-terminal domain disrupted both protein function and localization. Genetic analysis, colocalization, and biochemical experiments indicate that Prm3p interacts directly with Kar5p, suggesting that nuclear membrane fusion is mediated by a protein complex.
The Baker's Yeast Reduction of Keto-Esters in Organic Solvents: A One Week Research Project for Undergraduate Students

NASA Astrophysics Data System (ADS)

North, Michael

1998-05-01

An experiment has been designed which allows final year undergraduate students to carry out a mini-research project in one week and thus get a flavour of the joys and tribulations of conducting chemical research before they undertake a major research project. The experiment is an investigation into the reduction of alpha- or beta-keto esters using non-fermenting Baker's yeast in petroleum ether. There are a number of advantages to this method of using Baker's yeast, including a reduction in the amount of organic solvent used, and a much simplified purification procedure. During the course of the mini-project, the substrate specificity of the yeast is investigated, and the conditions for the optimisation of a particular keto ester are determined. Each product is analysed by a variety of analytical techniques including polarimetry, IR, NMR, and GC. In addition, the use of correct stereochemical nomenclature to describe prochiral, and chiral compounds as well as chemical reactions are discussed.
Novel endophytic yeast Rhodotorula mucilaginosa strain PTD3 I: production of xylitol and ethanol.

PubMed

Bura, Renata; Vajzovic, Azra; Doty, Sharon L

2012-07-01

An endophytic yeast, Rhodotorula mucilaginosa strain PTD3, that was isolated from stems of hybrid poplar was found to be capable of production of xylitol from xylose, of ethanol from glucose, galactose, and mannose, and of arabitol from arabinose. The utilization of 30 g/L of each of the five sugars during fermentation by PTD3 was studied in liquid batch cultures. Glucose-acclimated PTD3 produced enhanced yields of xylitol (67% of theoretical yield) from xylose and of ethanol (84, 86, and 94% of theoretical yield, respectively) from glucose, galactose, and mannose. Additionally, this yeast was capable of metabolizing high concentrations of mixed sugars (150 g/L), with high yields of xylitol (61% of theoretical yield) and ethanol (83% of theoretical yield). A 1:1 glucose:xylose ratio with 30 g/L of each during double sugar fermentation did not affect PTD3's ability to produce high yields of xylitol (65% of theoretical yield) and ethanol (92% of theoretical yield). Surprisingly, the highest yields of xylitol (76% of theoretical yield) and ethanol (100% of theoretical yield) were observed during fermentation of sugars present in the lignocellulosic hydrolysate obtained after steam pretreatment of a mixture of hybrid poplar and Douglas fir. PTD3 demonstrated an exceptional ability to ferment the hydrolysate, overcome hexose repression of xylose utilization with a short lag period of 10 h, and tolerate sugar degradation products. In direct comparison, PTD3 had higher xylitol yields from the mixed sugar hydrolysate compared with the widely studied and used xylitol producer Candida guilliermondii.
A Comparison of Two Yeast MnSODs: Mitochondrial Saccharomyces cerevisiae versus Cytosolic Candida albicans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheng Y.; Cabelli D.; Stich, T.A.

Human MnSOD is significantly more product-inhibited than bacterial MnSODs at high concentrations of superoxide (O{sub 2}{sup -}). This behavior limits the amount of H{sub 2}O{sub 2} produced at high [O{sub 2}{sup -}]; its desirability can be explained by the multiple roles of H{sub 2}O{sub 2} in mammalian cells, particularly its role in signaling. To investigate the mechanism of product inhibition in MnSOD, two yeast MnSODs, one from Saccharomyces cerevisiae mitochondria (ScMnSOD) and the other from Candida albicans cytosol (CaMnSODc), were isolated and characterized. ScMnSOD and CaMnSODc are similar in catalytic kinetics, spectroscopy, and redox chemistry, and they both rest predominantlymore » in the reduced state (unlike most other MnSODs). At high [O{sub 2}{sup -}], the dismutation efficiencies of the yeast MnSODs surpass those of human and bacterial MnSODs, due to very low level of product inhibition. Optical and parallel-mode electron paramagnetic resonance (EPR) spectra suggest the presence of two Mn{sup 3+} species in yeast Mn{sup 3+}SODs, including the well-characterized 5-coordinate Mn{sup 3+} species and a 6-coordinate L-Mn{sup 3+} species with hydroxide as the putative sixth ligand (L). The first and second coordination spheres of ScMnSOD are more similar to bacterial than to human MnSOD. Gln154, an H-bond donor to the Mn-coordinated solvent molecule, is slightly further away from Mn in yeast MnSODs, which may result in their unusual resting state. Mechanistically, the high efficiency of yeast MnSODs could be ascribed to putative translocation of an outer-sphere solvent molecule, which could destabilize the inhibited complex and enhance proton transfer from protein to peroxide. Our studies on yeast MnSODs indicate the unique nature of human MnSOD in that it predominantly undergoes the inhibited pathway at high [O{sub 2}{sup -}].« less
A Comparison of Two Yeast MnSODs: Mitochondrial Saccharomyces cerevisiae versus Cytosolic Candida albicans

PubMed Central

Sheng, Yuewei; Stich, Troy A.; Barnese, Kevin; Gralla, Edith B.; Cascio, Duilio; Britt, R. David; Cabelli, Diane E.; Valentine, Joan Selverstone

2011-01-01

Human MnSOD is significantly more product-inhibited than bacterial MnSODs at high concentrations of superoxide (O2−). This behavior limits the amount of H2O2 produced at high [O2−]; its desirability can be explained by the multiple roles of H2O2 in mammalian cells, particularly its role in signaling. To investigate the mechanism of product inhibition in MnSOD, two yeast MnSODs, one from Saccharomyces cerevisiae mitochondria (ScMnSOD) and the other from Candida albicans cytosol (CaMnSODc), were isolated and characterized. ScMnSOD and CaMnSODc are similar in catalytic kinetics, spectroscopy and redox chemistry, and they both rest predominantly in the reduced state (unlike most other MnSODs). At high [O2−] the dismutation efficiencies of the yeast MnSODs surpass those of human and bacterial MnSODs, due to very low level of product inhibition. Optical and parallel-mode electron paramagnetic resonance (EPR) spectra suggest the presence of two Mn3+ species in yeast Mn3+SODs, including the well-characterized 5-coordinate Mn3+ species and a 6-coordinate L-Mn3+ species with hydroxide as the putative sixth ligand (L). The first and second coordination spheres of ScMnSOD are more similar to bacterial than to human MnSOD. Gln154, an H-bond donor to the Mn-coordinated solvent molecule, is slightly further away from Mn in yeast MnSODs, which may result in their unusual resting state. Mechanistically, the high efficiency of yeast MnSODs could be ascribed to putative translocation of an outer-sphere solvent molecule, which could destabilize the inhibited complex and enhance proton transfer from protein to peroxide. Our studies on yeast MnSODs indicate the unique nature of human MnSOD in that it predominantly undergoes the inhibited pathway at high [O2−]. PMID:22077216
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. Copyright © 2016 Elsevier Ltd. All rights reserved.
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##
Sake yeast strains have difficulty in entering a quiescent state after cell growth cessation.

PubMed

Urbanczyk, Henryk; Noguchi, Chiemi; Wu, Hong; Watanabe, Daisuke; Akao, Takeshi; Takagi, Hiroshi; Shimoi, Hitoshi

2011-07-01

Sake yeast strains produce a high concentration of ethanol during sake brewing compared to laboratory yeast strains. As ethanol fermentation by yeast cells continues even after cell growth stops, analysis of the physiological state of the stationary phase cells is very important for understanding the mechanism of producing higher concentrations of ethanol. We compared the physiological characteristics of stationary phase cells of both sake and laboratory yeast strains in an aerobic batch culture and under sake brewing conditions. We unexpectedly found that sake yeast cells in the stationary phase had a lower buoyant density and stress tolerance than did the laboratory yeast cells under both experimental conditions. These results suggest that it is difficult for sake yeast cells to enter a quiescent state after cell growth has stopped, which may be one reason for the higher fermentation rate of sake yeast compared to laboratory yeast strains. Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.
Independent Evolution of Winner Traits without Whole Genome Duplication in Dekkera Yeasts.

PubMed

Guo, Yi-Cheng; Zhang, Lin; Dai, Shao-Xing; Li, Wen-Xing; Zheng, Jun-Juan; Li, Gong-Hua; Huang, Jing-Fei

2016-01-01

Dekkera yeasts have often been considered as alternative sources of ethanol production that could compete with S. cerevisiae. The two lineages of yeasts independently evolved traits that include high glucose and ethanol tolerance, aerobic fermentation, and a rapid ethanol fermentation rate. The Saccharomyces yeasts attained these traits mainly through whole genome duplication approximately 100 million years ago (Mya). However, the Dekkera yeasts, which were separated from S. cerevisiae approximately 200 Mya, did not undergo whole genome duplication (WGD) but still occupy a niche similar to S. cerevisiae. Upon analysis of two Dekkera yeasts and five closely related non-WGD yeasts, we found that a massive loss of cis-regulatory elements occurred in an ancestor of the Dekkera yeasts, which led to improved mitochondrial functions similar to the S. cerevisiae yeasts. The evolutionary analysis indicated that genes involved in the transcription and translation process exhibited faster evolution in the Dekkera yeasts. We detected 90 positively selected genes, suggesting that the Dekkera yeasts evolved an efficient translation system to facilitate adaptive evolution. Moreover, we identified that 12 vacuolar H+-ATPase (V-ATPase) function genes that were under positive selection, which assists in developing tolerance to high alcohol and high sugar stress. We also revealed that the enzyme PGK1 is responsible for the increased rate of glycolysis in the Dekkera yeasts. These results provide important insights to understand the independent adaptive evolution of the Dekkera yeasts and provide tools for genetic modification promoting industrial usage.
Independent Evolution of Winner Traits without Whole Genome Duplication in Dekkera Yeasts

PubMed Central

Dai, Shao-Xing; Li, Wen-Xing; Zheng, Jun-Juan; Li, Gong-Hua; Huang, Jing-Fei

2016-01-01

Dekkera yeasts have often been considered as alternative sources of ethanol production that could compete with S. cerevisiae. The two lineages of yeasts independently evolved traits that include high glucose and ethanol tolerance, aerobic fermentation, and a rapid ethanol fermentation rate. The Saccharomyces yeasts attained these traits mainly through whole genome duplication approximately 100 million years ago (Mya). However, the Dekkera yeasts, which were separated from S. cerevisiae approximately 200 Mya, did not undergo whole genome duplication (WGD) but still occupy a niche similar to S. cerevisiae. Upon analysis of two Dekkera yeasts and five closely related non-WGD yeasts, we found that a massive loss of cis-regulatory elements occurred in an ancestor of the Dekkera yeasts, which led to improved mitochondrial functions similar to the S. cerevisiae yeasts. The evolutionary analysis indicated that genes involved in the transcription and translation process exhibited faster evolution in the Dekkera yeasts. We detected 90 positively selected genes, suggesting that the Dekkera yeasts evolved an efficient translation system to facilitate adaptive evolution. Moreover, we identified that 12 vacuolar H+-ATPase (V-ATPase) function genes that were under positive selection, which assists in developing tolerance to high alcohol and high sugar stress. We also revealed that the enzyme PGK1 is responsible for the increased rate of glycolysis in the Dekkera yeasts. These results provide important insights to understand the independent adaptive evolution of the Dekkera yeasts and provide tools for genetic modification promoting industrial usage. PMID:27152421
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
Get Cooking with Chemistry!

ERIC Educational Resources Information Center

American Chemical Society, Washington, DC.

This book presents science activities investigating the chemical changes and reactions with powders that are used in baking. Activities include: (1) Mystery Powders; (2) Find the Fizz: Discover the Secret of Baking Powder; and (3) A Feast for Yeast and Cheese: Behold the Power of Chemistry. (YDS)
Genome dynamics and evolution in yeasts: A long-term yeast-bacteria competition experiment

PubMed Central

Katz, Michael; Knecht, Wolfgang; Compagno, Concetta; Piškur, Jure

2018-01-01

There is an enormous genetic diversity evident in modern yeasts, but our understanding of the ecological basis of such diversifications in nature remains at best fragmented so far. Here we report a long-term experiment mimicking a primordial competitive environment, in which yeast and bacteria co-exist and compete against each other. Eighteen yeasts covering a wide phylogenetic background spanning approximately 250 million years of evolutionary history were used to establish independent evolution lines for at most 130 passages. Our collection of hundreds of modified strains generated through such a rare two-species cross-kingdom competition experiment re-created the appearance of large-scale genomic rearrangements and altered phenotypes important in the diversification history of yeasts. At the same time, the methodology employed in this evolutionary study would also be a non-gene-technological method of reprogramming yeast genomes and then selecting yeast strains with desired traits. Cross-kingdom competition may therefore be a method of significant value to generate industrially useful yeast strains with new metabolic traits. PMID:29624585
Electron beam radiation of dried fruits and nuts to reduce yeast and mold bioburden.

PubMed

Ic, Erhan; Kottapalli, Bala; Maxim, Joseph; Pillai, Suresh D

2007-04-01

Dried fruits and nuts make up a significant portion of the commodities traded globally, and the presence of yeasts and molds on dried fruits and nuts can be a public health risk because of the potential for exposure to toxigenic fungi. Since current postharvest treatment technologies are rather limited for dried fruits and nuts, electron beam (E-beam) radiation experiments were performed to determine the doses required to reduce the yeast and mold bioburden of raisins, walnuts, and dates. The indigenous yeast and mold bioburden on a select number of commodities sold at retail ranged from 10(2) to 10(3) CFU/g. E-beam inactivation kinetics based on the linear model suggest that the decimal reduction dose required to eliminate 90% of the microbial population (D10-value) of these indigenous fungal populations ranges from 1.09 to 1.59 kGy. Some samples, however, exhibited inactivation kinetics that were better modeled by a quadratic model. The results indicate that different commodities can contain molds and yeasts of varying resistance to ionizing radiation. It is thus essential for the dried fruit and nut industry to determine empirically the minimum E-beam dose that is capable of reducing or eliminating the bioburden of yeasts and molds in their specific commodities.
The C Terminus of the Histone Chaperone Asf1 Cross-Links to Histone H3 in Yeast and Promotes Interaction with Histones H3 and H4

PubMed Central

Dennehey, Briana K.; Noone, Seth; Liu, Wallace H.; Smith, Luke

2013-01-01

The central histone H3/H4 chaperone Asf1 comprises a highly conserved globular core and a divergent C-terminal tail. While the function and structure of the Asf1 core are well known, the function of the tail is less well understood. Here, we have explored the role of the yeast (yAsf1) and human (hAsf1a and hAsf1b) Asf1 tails in Saccharomyces cerevisiae. We show, using a photoreactive, unnatural amino acid, that Asf1 tail residue 210 cross-links to histone H3 in vivo and, further, that loss of C-terminal tail residues 211 to 279 weakens yAsf1-histone binding affinity in vitro nearly 200-fold. Via several yAsf1 C-terminal truncations and yeast-human chimeric proteins, we found that truncations at residue 210 increase transcriptional silencing and that the hAsf1a tail partially substitutes for full-length yAsf1 with respect to silencing but that full-length hAsf1b is a better overall substitute for full-length yAsf1. In addition, we show that the C-terminal tail of Asf1 is phosphorylated at T270 in yeast. Loss of this phosphorylation site does not prevent coimmunoprecipitation of yAsf1 and Rad53 from yeast extracts, whereas amino acid residue substitutions at the Asf1-histone H3/H4 interface do. Finally, we show that residue substitutions in yAsf1 near the CAF-1/HIRA interface also influence yAsf1's function in silencing. PMID:23184661
Yeast selection for fuel ethanol production in Brazil.

PubMed

Basso, Luiz C; de Amorim, Henrique V; de Oliveira, Antonio J; Lopes, Mario L

2008-11-01

Brazil is one of the largest ethanol biofuel producers and exporters in the world and its production has increased steadily during the last three decades. The increasing efficiency of Brazilian ethanol plants has been evident due to the many technological contributions. As far as yeast is concerned, few publications are available regarding the industrial fermentation processes in Brazil. The present paper reports on a yeast selection program performed during the last 12 years aimed at selecting Saccharomyces cerevisiae strains suitable for fermentation of sugar cane substrates (cane juice and molasses) with cell recycle, as it is conducted in Brazilian bioethanol plants. As a result, some evidence is presented showing the positive impact of selected yeast strains in increasing ethanol yield and reducing production costs, due to their higher fermentation performance (high ethanol yield, reduced glycerol and foam formation, maintenance of high viability during recycling and very high implantation capability into industrial fermenters). Results also suggest that the great yeast biodiversity found in distillery environments could be an important source of strains. This is because during yeast cell recycling, selective pressure (an adaptive evolution) is imposed on cells, leading to strains with higher tolerance to the stressful conditions of the industrial fermentation.

Improvement of fermentation ability under baking-associated stress conditions by altering the POG1 gene expression in baker's yeast.

PubMed

Sasano, Yu; Haitani, Yutaka; Hashida, Keisuke; Oshiro, Satoshi; Shima, Jun; Takagi, Hiroshi

2013-08-01

During the bread-making process, yeast cells are exposed to many types of baking-associated stress. There is thus a demand within the baking industry for yeast strains with high fermentation abilities under these stress conditions. The POG1 gene, encoding a putative transcription factor involved in cell cycle regulation, is a multicopy suppressor of the yeast Saccharomyces cerevisiae E3 ubiquitin ligase Rsp5 mutant. The pog1 mutant is sensitive to various stresses. Our results suggested that the POG1 gene is involved in stress tolerance in yeast cells. In this study, we showed that overexpression of the POG1 gene in baker's yeast conferred increased fermentation ability in high-sucrose-containing dough, which is used for sweet dough baking. Furthermore, deletion of the POG1 gene drastically increased the fermentation ability in bread dough after freeze-thaw stress, which would be a useful characteristic for frozen dough baking. Thus, the engineering of yeast strains to control the POG1 gene expression level would be a novel method for molecular breeding of baker's yeast. Copyright © 2013 Elsevier B.V. All rights reserved.
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
Characterization of pectinase activity for enology from yeasts occurring in Argentine Bonarda grape.

PubMed

Merín, María Gabriela; Martín, María Carolina; Rantsiou, Kalliopi; Cocolin, Luca; de Ambrosini, Vilma Inés Morata

2015-01-01

Pectinolytic enzymes are greatly important in winemaking due to their ability to degrade pectic polymers from grape, contributing to enhance process efficiency and wine quality. This study aimed to analyze the occurrence of pectinolytic yeasts during spontaneous fermentation of Argentine Bonarda grape, to select yeasts that produce extracellular pectinases and to characterize their pectinolytic activity under wine-like conditions. Isolated yeasts were grouped using PCR-DGGE and identified by partial sequencing of 26S rRNA gene. Isolates comprised 7 genera, with Aureobasidium pullulans as the most predominant pectinolytic species, followed by Rhodotorula dairenensis and Cryptococcus saitoi. No pectinolytic activity was detected among ascomycetous yeasts isolated on grapes and during fermentation, suggesting a low occurrence of pectinolytic yeast species in wine fermentation ecosystem. This is the first study reporting R. dairenensis and Cr. saitoi species with pectinolytic activity. R. dairenensis GM-15 produced pectinases that proved to be highly active at grape pH, at 12 °C, and under ethanol and SO2 concentrations usually found in vinifications (pectinase activity around 1.1 U/mL). This strain also produced cellulase activity at 12 °C and pH 3.5, but did not produce β-glucosidase activity under these conditions. The strain showed encouraging enological properties for its potential use in low-temperature winemaking.
Characterization of pectinase activity for enology from yeasts occurring in Argentine Bonarda grape

PubMed Central

Merín, María Gabriela; Martín, María Carolina; Rantsiou, Kalliopi; Cocolin, Luca; de Ambrosini, Vilma Inés Morata

2015-01-01

Pectinolytic enzymes are greatly important in winemaking due to their ability to degrade pectic polymers from grape, contributing to enhance process efficiency and wine quality. This study aimed to analyze the occurrence of pectinolytic yeasts during spontaneous fermentation of Argentine Bonarda grape, to select yeasts that produce extracellular pectinases and to characterize their pectinolytic activity under wine-like conditions. Isolated yeasts were grouped using PCR-DGGE and identified by partial sequencing of 26S rRNA gene. Isolates comprised 7 genera, with Aureobasidium pullulans as the most predominant pectinolytic species, followed by Rhodotorula dairenensis and Cryptococcus saitoi. No pectinolytic activity was detected among ascomycetous yeasts isolated on grapes and during fermentation, suggesting a low occurrence of pectinolytic yeast species in wine fermentation ecosystem. This is the first study reporting R. dairenensis and Cr. saitoi species with pectinolytic activity. R. dairenensis GM-15 produced pectinases that proved to be highly active at grape pH, at 12 °C, and under ethanol and SO2 concentrations usually found in vinifications (pectinase activity around 1.1 U/mL). This strain also produced cellulase activity at 12 °C and pH 3.5, but did not produce β-glucosidase activity under these conditions. The strain showed encouraging enological properties for its potential use in low-temperature winemaking. PMID:26413065
Repeat-Associated Fission Yeast-Like Regional Centromeres in the Ascomycetous Budding Yeast Candida tropicalis

PubMed Central

Chatterjee, Gautam; Sankaranarayanan, Sundar Ram; Guin, Krishnendu; Thattikota, Yogitha; Padmanabhan, Sreedevi; Siddharthan, Rahul; Sanyal, Kaustuv

2016-01-01

The centromere, on which kinetochore proteins assemble, ensures precise chromosome segregation. Centromeres are largely specified by the histone H3 variant CENP-A (also known as Cse4 in yeasts). Structurally, centromere DNA sequences are highly diverse in nature. However, the evolutionary consequence of these structural diversities on de novo CENP-A chromatin formation remains elusive. Here, we report the identification of centromeres, as the binding sites of four evolutionarily conserved kinetochore proteins, in the human pathogenic budding yeast Candida tropicalis. Each of the seven centromeres comprises a 2 to 5 kb non-repetitive mid core flanked by 2 to 5 kb inverted repeats. The repeat-associated centromeres of C. tropicalis all share a high degree of sequence conservation with each other and are strikingly diverged from the unique and mostly non-repetitive centromeres of related Candida species—Candida albicans, Candida dubliniensis, and Candida lusitaniae. Using a plasmid-based assay, we further demonstrate that pericentric inverted repeats and the underlying DNA sequence provide a structural determinant in CENP-A recruitment in C. tropicalis, as opposed to epigenetically regulated CENP-A loading at centromeres in C. albicans. Thus, the centromere structure and its influence on de novo CENP-A recruitment has been significantly rewired in closely related Candida species. Strikingly, the centromere structural properties along with role of pericentric repeats in de novo CENP-A loading in C. tropicalis are more reminiscent to those of the distantly related fission yeast Schizosaccharomyces pombe. Taken together, we demonstrate, for the first time, fission yeast-like repeat-associated centromeres in an ascomycetous budding yeast. PMID:26845548
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Uncoupling reproduction from metabolism extends chronological lifespan in yeast

PubMed Central

Nagarajan, Saisubramanian; Kruckeberg, Arthur L.; Schmidt, Karen H.; Kroll, Evgueny; Hamilton, Morgan; McInnerney, Kate; Summers, Ryan; Taylor, Timothy; Rosenzweig, Frank

2014-01-01

Studies of replicative and chronological lifespan in Saccharomyces cerevisiae have advanced understanding of longevity in all eukaryotes. Chronological lifespan in this species is defined as the age-dependent viability of nondividing cells. To date this parameter has only been estimated under calorie restriction, mimicked by starvation. Because postmitotic cells in higher eukaryotes often do not starve, we developed a model yeast system to study cells as they age in the absence of calorie restriction. Yeast cells were encapsulated in a matrix consisting of calcium alginate to form ∼3 mm beads that were packed into bioreactors and fed ad libitum. Under these conditions cells ceased to divide, became heat shock and zymolyase resistant, yet retained high fermentative capacity. Over the course of 17 d, immobilized yeast cells maintained >95% viability, whereas the viability of starving, freely suspended (planktonic) cells decreased to <10%. Immobilized cells exhibited a stable pattern of gene expression that differed markedly from growing or starving planktonic cells, highly expressing genes in glycolysis, cell wall remodeling, and stress resistance, but decreasing transcription of genes in the tricarboxylic acid cycle, and genes that regulate the cell cycle, including master cyclins CDC28 and CLN1. Stress resistance transcription factor MSN4 and its upstream effector RIM15 are conspicuously up-regulated in the immobilized state, and an immobilized rim15 knockout strain fails to exhibit the long-lived, growth-arrested phenotype, suggesting that altered regulation of the Rim15-mediated nutrient-sensing pathway plays an important role in extending yeast chronological lifespan under calorie-unrestricted conditions. PMID:24706810
Effects of different yeast cell wall supplements added to maize- or wheat-based diets for broiler chickens.

PubMed

Morales-López, R; Auclair, E; Van Immerseel, F; Ducatelle, R; García, F; Brufau, J

2010-06-01

1. Three experiments were carried out to study the effects of two experimental yeast cell wall (YCW) supplements, one from the yeast extract industry and the other from the brewery industry, added to maize or wheat based-diets, on performance and intestinal parameters of broiler chickens (Ross 308). 2. In the first and second experiments, a completely randomised block design with 4 experimental treatments was used: T-1) Negative control, no additives T-2) Positive control, avilamycin group (10 mg/kg feed), T-3) Yeast extract-YCW (500 mg/kg), and T-4) Brewery-YCW (500 mg/kg feed). There were 6 replicates of 20 (experiment 1) and 22 (experiment 2) chicks per treatment. 3. In experiment 1 (wheat based diets), yeast extract-YCW increased BW and daily feed intake (42 d). The effects were comparable to those of avilamycin. In experiment 2 (maize based diet), avilamycin, yeast extract-YCW and brewery-YCW treatments improved the feed conversion ratio with respect to the negative control group (0 to 14 d). 4. At 24 d, in both experiments, the ileal nutrient digestibility and ileal bacterial counts were not affected by any experimental treatment. In maize diets, lower intestinal viscosity was obtained with avilamycin, yeast extract-YCW and brewery-YCW than with the negative control. In wheat diets, yeast extract-YCW and brewery-YCW reduced intestinal viscosity. 5. A third experiment was conducted to study the effect of yeast extract-YCW on animal performance, intestinal mucosa morphology and intestinal viscosity. A 2 x 2 factorial arrangement of treatments was used; one factor was the dietary yeast extract-YCW supplementation (0 or 500 mg/kg feed) and the other the cereal in the diet (maize or wheat). 6. At 43 d, the heaviest BW was in chickens fed on yeast extract-YCW compared to those given the negative control. At 22 d, yeast extract-YCW increased villus height, mucus thickness and number of goblet cells with respect to negative control. 7. Results of these experiments
Succinic acid production by Actinobacillus succinogenes using hydrolysates of spent yeast cells and corn fiber.

PubMed

Chen, Ke-Quan; Li, Jian; Ma, Jiang-Feng; Jiang, Min; Wei, Ping; Liu, Zhong-Min; Ying, Han-Jie

2011-01-01

The enzymatic hydrolysate of spent yeast cells was evaluated as a nitrogen source for succinic acid production by Actinobacillus succinogenes NJ113, using corn fiber hydrolysate as a carbon source. When spent yeast cell hydrolysate was used directly as a nitrogen source, a maximum succinic acid concentration of 35.5 g/l was obtained from a glucose concentration of 50 g/l, with a glucose utilization of 95.2%. Supplementation with individual vitamins showed that biotin was the most likely factor to be limiting for succinic acid production with spent yeast cell hydrolysate. After supplementing spent yeast cell hydrolysate and 90 g/l of glucose with 150 μg/l of biotin, cell growth increased 32.5%, glucose utilization increased 37.6%, and succinic acid concentration was enhanced 49.0%. As a result, when biotin-supplemented spent yeast cell hydrolysate was used with corn fiber hydrolysate, a succinic acid yield of 67.7% was obtained from 70.3 g/l of total sugar concentration, with a productivity of 0.63 g/(l h). Our results suggest that biotin-supplemented spent yeast cell hydrolysate may be an alternative nitrogen source for the efficient production of succinic acid by A. succinogenes NJ113, using renewable resources. Crown Copyright Â© 2010. Published by Elsevier Ltd. All rights reserved.
The use of lactic acid-producing, malic acid-producing, or malic acid-degrading yeast strains for acidity adjustment in the wine industry.

PubMed

Su, Jing; Wang, Tao; Wang, Yun; Li, Ying-Ying; Li, Hua

2014-03-01

In an era of economic globalization, the competition among wine businesses is likely to get tougher. Biotechnological innovation permeates the entire world and intensifies the severity of the competition of the wine industry. Moreover, modern consumers preferred individualized, tailored, and healthy and top quality wine products. Consequently, these two facts induce large gaps between wine production and wine consumption. Market-orientated yeast strains are presently being selected or developed for enhancing the core competitiveness of wine enterprises. Reasonable biological acidity is critical to warrant a high-quality wine. Many wild-type acidity adjustment yeast strains have been selected all over the world. Moreover, mutation breeding, metabolic engineering, genetic engineering, and protoplast fusion methods are used to construct new acidity adjustment yeast strains to meet the demands of the market. In this paper, strategies and concepts for strain selection or improvement methods were discussed, and many examples based upon selected studies involving acidity adjustment yeast strains were reviewed. Furthermore, the development of acidity adjustment yeast strains with minimized resource inputs, improved fermentation, and enological capabilities for an environmentally friendly production of healthy, top quality wine is presented.
A large-scale full-length cDNA analysis to explore the budding yeast transcriptome

PubMed Central

Miura, Fumihito; Kawaguchi, Noriko; Sese, Jun; Toyoda, Atsushi; Hattori, Masahira; Morishita, Shinichi; Ito, Takashi

2006-01-01

We performed a large-scale cDNA analysis to explore the transcriptome of the budding yeast Saccharomyces cerevisiae. We sequenced two cDNA libraries, one from the cells exponentially growing in a minimal medium and the other from meiotic cells. Both libraries were generated by using a vector-capping method that allows the accurate mapping of transcription start sites (TSSs). Consequently, we identified 11,575 TSSs associated with 3,638 annotated genomic features, including 3,599 ORFs, to suggest that most yeast genes have two or more TSSs. In addition, we identified 45 previously undescribed introns, including those affecting current ORF annotations and those spliced alternatively. Furthermore, the analysis revealed 667 transcription units in the intergenic regions and transcripts derived from antisense strands of 367 known features. We also found that 348 ORFs carry TSSs in their 3′-halves to generate sense transcripts starting from inside the ORFs. These results indicate that the budding yeast transcriptome is considerably more complex than previously thought, and it shares many recently revealed characteristics with the transcriptomes of mammals and other higher eukaryotes. Thus, the genome-wide active transcription that generates novel classes of transcripts appears to be an intrinsic feature of the eukaryotic cells. The budding yeast will serve as a versatile model for the studies on these aspects of transcriptome, and the full-length cDNA clones can function as an invaluable resource in such studies. PMID:17101987
Effects of black yeast-derived β-1,3-1,6-glucan on serum cytokine and microRNA expression in transplanted sarcoma in mice.

PubMed

Li, Wei; Zhang, Yaru; Cong, Fengsong

2013-01-01

β-1,3-1,6-glucans are the most abundant glucose polymers in the cell walls of fungi. Previous studies have shown that β-1,3-1,6-glucans derived from fungi possess immunomodulating activitivies. Antitumor effects of these compounds have also been reported in animal models. Current studies mainly focus on the direct effects of β-1,3-1,6-glucans on immune systems, but no data are available to address the underlying molecular events in tumor cells. β-1,3-1,6-glucan purified from black yeast at 5 mg/100 g body weight (study group) or saline (control group) was intragastrically administered on a daily basis to subcutaneously-injected mice with mouse S180 sarcoma cells. Tumor sizes, tumor weights, serum concentrations of cytokines and levels of microRNAs (miRNAs) in transplanted tumors were compared between the treated and control groups. The volumes and weights of transplanted tumors were significantly lower in the treatment groups compared to the control groups by ∼150% and 70%, respectively. The treated mice demonstrated significantly higher levels of cytokines, including IL-2, IL-4, IL-6, IL-8, IL-10 and IL-12, compared to the control mice. Notably, the expression of several miRNAs in transplanted tumor tissues also markedly changed. These data suggest that black yeast-derived β-1,3-1,6-glucan, not only stimulates cytokine release from immune cells, but also changes the expression profiles of miRNAs in transplanted tumors.
Effects of black yeast-derived β-1,3-1,6-glucan on serum cytokine and microRNA expression in transplanted sarcoma in mice

PubMed Central

LI, WEI; ZHANG, YARU; CONG, FENGSONG

2013-01-01

β-1,3-1,6-glucans are the most abundant glucose polymers in the cell walls of fungi. Previous studies have shown that β-1,3-1,6-glucans derived from fungi possess immunomodulating activitivies. Antitumor effects of these compounds have also been reported in animal models. Current studies mainly focus on the direct effects of β-1,3-1,6-glucans on immune systems, but no data are available to address the underlying molecular events in tumor cells. β-1,3-1,6-glucan purified from black yeast at 5 mg/100 g body weight (study group) or saline (control group) was intragastrically administered on a daily basis to subcutaneously-injected mice with mouse S180 sarcoma cells. Tumor sizes, tumor weights, serum concentrations of cytokines and levels of microRNAs (miRNAs) in transplanted tumors were compared between the treated and control groups. The volumes and weights of transplanted tumors were significantly lower in the treatment groups compared to the control groups by ∼150% and 70%, respectively. The treated mice demonstrated significantly higher levels of cytokines, including IL-2, IL-4, IL-6, IL-8, IL-10 and IL-12, compared to the control mice. Notably, the expression of several miRNAs in transplanted tumor tissues also markedly changed. These data suggest that black yeast-derived β-1,3-1,6-glucan, not only stimulates cytokine release from immune cells, but also changes the expression profiles of miRNAs in transplanted tumors. PMID:24648910
Yeast Prions and Human Prion-like Proteins: Sequence Features and Prediction Methods

PubMed Central

Cascarina, Sean; Ross, Eric D.

2014-01-01

Prions are self-propagating infectious protein isoforms. A growing number of prions have been identified in yeast, each resulting from the conversion of soluble proteins into an insoluble amyloid form. These yeast prions have served as a powerful model system for studying the causes and consequences of prion aggregation. Remarkably, a number of human proteins containing prion-like domains, defined as domains with compositional similarity to yeast prion domains, have recently been linked to various human degenerative diseases, including amyotrophic lateral sclerosis (ALS). This suggests that the lessons learned from yeast prions may help in understanding these human diseases. In this review, we examine what has been learned about the amino acid sequence basis for prion aggregation in yeast, and how this information has been used to develop methods to predict aggregation propensity. We then discuss how this information is being applied to understand human disease, and the challenges involved in applying yeast prediction methods to higher organisms. PMID:24390581
Yeast prions and human prion-like proteins: sequence features and prediction methods.

PubMed

Cascarina, Sean M; Ross, Eric D

2014-06-01

Prions are self-propagating infectious protein isoforms. A growing number of prions have been identified in yeast, each resulting from the conversion of soluble proteins into an insoluble amyloid form. These yeast prions have served as a powerful model system for studying the causes and consequences of prion aggregation. Remarkably, a number of human proteins containing prion-like domains, defined as domains with compositional similarity to yeast prion domains, have recently been linked to various human degenerative diseases, including amyotrophic lateral sclerosis. This suggests that the lessons learned from yeast prions may help in understanding these human diseases. In this review, we examine what has been learned about the amino acid sequence basis for prion aggregation in yeast, and how this information has been used to develop methods to predict aggregation propensity. We then discuss how this information is being applied to understand human disease, and the challenges involved in applying yeast prediction methods to higher organisms.
Quantifying variation in the ability of yeasts to attract Drosophila melanogaster.

PubMed

Palanca, Loida; Gaskett, Anne C; Günther, Catrin S; Newcomb, Richard D; Goddard, Matthew R

2013-01-01

Yeasts that invade and colonise fruit significantly enhance the volatile chemical diversity of this ecosystem. These modified bouquets are thought to be more attractive to Drosophila flies than the fruit alone, but the variance of attraction in natural yeast populations is uncharacterised. Here we investigate how a range of yeast isolates affect the attraction of female D. melanogaster to fruit in a simple two choice assay comparing yeast to sterile fruit. Of the 43 yeast isolates examined, 33 were attractive and seven repellent to the flies. The results of isolate-versus-isolate comparisons provided the same relative rankings. Attractiveness varied significantly by yeast, with the strongly fermenting Saccharomyces species generally being more attractive than the mostly respiring non-Saccharomyces species (P = 0.0035). Overall the habitat (fruit or other) from which the isolates were directly sampled did not explain attraction (P = 0.2352). However, yeasts isolated from fruit associated niches were more attractive than those from non-fruit associated niches (P = 0.0188) regardless of taxonomic positioning. These data suggest that while attractiveness is primarily correlated with phylogenetic status, the ability to attract Drosophila is a labile trait among yeasts that is potentially associated with those inhabiting fruit ecosystems. Preliminary analysis of the volatiles emitted by four yeast isolates in grape juice show the presence/absence of ethanol and acetic acid were not likely explanations for the observed variation in attraction. These data demonstrate variation among yeasts for their ability to attract Drosophila in a pattern that is consistent with the hypothesis that certain yeasts are manipulating fruit odours to mediate interactions with their Drosophila dispersal agent.
Primers-4-Yeast: a comprehensive web tool for planning primers for Saccharomyces cerevisiae.

PubMed

Yofe, Ido; Schuldiner, Maya

2014-02-01

The budding yeast Saccharomyces cerevisiae is a key model organism of functional genomics, due to its ease and speed of genetic manipulations. In fact, in this yeast, the requirement for homologous sequences for recombination purposes is so small that 40 base pairs (bp) are sufficient. Hence, an enormous variety of genetic manipulations can be performed by simply planning primers with the correct homology, using a defined set of transformation plasmids. Although designing primers for yeast transformations and for the verification of their correct insertion is a common task in all yeast laboratories, primer planning is usually done manually and a tool that would enable easy, automated primer planning for the yeast research community is still lacking. Here we introduce Primers-4-Yeast, a web tool that allows primers to be designed in batches for S. cerevisiae gene-targeting transformations, and for the validation of correct insertions. This novel tool enables fast, automated, accurate primer planning for large sets of genes, introduces consistency in primer planning and is therefore suggested to serve as a standard in yeast research. Primers-4-Yeast is available at: http://www.weizmann.ac.il/Primers-4-Yeast Copyright © 2013 John Wiley & Sons, Ltd.
New yeasts-new brews: modern approaches to brewing yeast design and development.

PubMed

Gibson, B; Geertman, J-M A; Hittinger, C T; Krogerus, K; Libkind, D; Louis, E J; Magalhães, F; Sampaio, J P

2017-06-01

The brewing industry is experiencing a period of change and experimentation largely driven by customer demand for product diversity. This has coincided with a greater appreciation of the role of yeast in determining the character of beer and the widespread availability of powerful tools for yeast research. Genome analysis in particular has helped clarify the processes leading to domestication of brewing yeast and has identified domestication signatures that may be exploited for further yeast development. The functional properties of non-conventional yeast (both Saccharomyces and non-Saccharomyces) are being assessed with a view to creating beers with new flavours as well as producing flavoursome non-alcoholic beers. The discovery of the psychrotolerant S. eubayanus has stimulated research on de novo S. cerevisiae × S. eubayanus hybrids for low-temperature lager brewing and has led to renewed interest in the functional importance of hybrid organisms and the mechanisms that determine hybrid genome function and stability. The greater diversity of yeast that can be applied in brewing, along with an improved understanding of yeasts' evolutionary history and biology, is expected to have a significant and direct impact on the brewing industry, with potential for improved brewing efficiency, product diversity and, above all, customer satisfaction. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
A Method of Visualizing Three-Dimensional Distribution of Yeast in Bread Dough

NASA Astrophysics Data System (ADS)

Maeda, Tatsurou; Do, Gab-Soo; Sugiyama, Junichi; Oguchi, Kosei; Shiraga, Seizaburou; Ueda, Mitsuyoshi; Takeya, Koji; Endo, Shigeru

A novel technique was developed to monitor the change in three-dimensional (3D) distribution of yeast in frozen bread dough samples in accordance with the progress of mixing process. Application of a surface engineering technology allowed the identification of yeast in bread dough by bonding EGFP (Enhanced Green Fluorescent Protein) to the surface of yeast cells. The fluorescent yeast (a biomarker) was recognized as bright spots at the wavelength of 520 nm. A Micro-Slicer Image Processing System (MSIPS) with a fluorescence microscope was utilized to acquire cross-sectional images of frozen dough samples sliced at intervals of 1 μm. A set of successive two-dimensional images was reconstructed to analyze 3D distribution of yeast. Samples were taken from each of four normal mixing stages (i.e., pick up, clean up, development, and final stages) and also from over mixing stage. In the pick up stage yeast distribution was uneven with local areas of dense yeast. As the mixing progressed from clean up to final stages, the yeast became more evenly distributed throughout the dough sample. However, the uniformity in yeast distribution was lost in the over mixing stage possibly due to the breakdown of gluten structure within the dough sample.
Antimicrobial activity of yeasts against some pathogenic bacteria

PubMed Central

Younis, Gamal; Awad, Amal; Dawod, Rehab E.; Yousef, Nehal E.

2017-01-01

Aim: This study was designed to isolate and identify yeast species from milk and meat products, and to test their antimicrobial activity against some bacterial species. Materials and Methods: A total of 160 milk and meat products samples were collected from random sellers and super markets in New Damietta city, Damietta, Egypt. Samples were subjected to yeast isolation procedures and tested for its antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. In addition, all yeast species isolates were subjected to polymerase chain reaction (PCR) for detection of khs (kievitone hydratase) and pelA (pectate degrading enzyme)genes. Results: The recovery rate of yeasts from sausage was 20% (2/10) followed by kareish cheese, processed cheese, and butter 10% (1/10) each as well as raw milk 9% (9/100), and fruit yoghurt 30% (6/20). Different yeast species were recovered, namely, Candida kefyr (5 isolates), Saccharomyces cerevisiae (4 isolates), Candida intermedia (3 isolates), Candida tropicalis (2 isolates), Candida lusitaniae (2 isolates), and Candida krusei (1 isolate). khs gene was detected in all S. cerevisiae isolates, however, pelA gene was not detected in all identified yeast species. Antimicrobial activity of recovered yeasts against the selected bacterial species showed high activity with C. intermedia against S. aureus and E. coli, C. kefyr against E. coli, and C. lusitaniae against S. aureus. Moderate activities were obtained with C. tropicalis, C. lusitaniae, and S. cerevisiae against E. coli; meanwhile, all the tested yeasts revealed a very low antimicrobial activity against P. aeruginosa. Conclusion: The obtained results confirmed that some kinds of yeasts have the ability to produce antimicrobial compounds that could inhibit some pathogenic and spoilage bacteria and these antimicrobial activity of yeasts enables them to be one of the novel agents in controlling spoilage of food. PMID:28919693

Yeast Modulation of Human Dendritic Cell Cytokine Secretion: An In Vitro Study

PubMed Central

Smith, Ida M.; Christensen, Jeffrey E.; Arneborg, Nils; Jespersen, Lene

2014-01-01

Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. The concept of individual microorganisms influencing the makeup of T cell subsets via interactions with intestinal dendritic cells (DCs) appears to constitute the foundation for immunoregulatory effects of probiotics, and several studies have reported probiotic strains resulting in reduction of intestinal inflammation through modulation of DC function. Consequent to a focus on Saccharomyces boulardii as the fundamental probiotic yeast, very little is known about hundreds of non-Saccharomyces yeasts in terms of their interaction with the human gastrointestinal immune system. The aim of the present study was to evaluate 170 yeast strains representing 75 diverse species for modulation of inflammatory cytokine secretion by human DCs in vitro, as compared to cytokine responses induced by a S. boulardii reference strain with probiotic properties documented in clinical trials. Furthermore, we investigated whether cytokine inducing interactions between yeasts and human DCs are dependent upon yeast viability or rather a product of membrane interactions regardless of yeast metabolic function. We demonstrate high diversity in yeast induced cytokine profiles and employ multivariate data analysis to reveal distinct clustering of yeasts inducing similar cytokine profiles in DCs, highlighting clear species distinction within specific yeast genera. The observed differences in induced DC cytokine profiles add to the currently very limited knowledge of the cross-talk between yeasts and human immune cells and provide a foundation for selecting yeast strains for further characterization and development toward potentially novel yeast probiotics. Additionally, we present data to support a hypothesis that the interaction between yeasts and human DCs does not solely depend on yeast viability, a concept which may suggest a need for further classifications beyond the current
A new methodology to obtain wine yeast strains overproducing mannoproteins.

PubMed

Quirós, Manuel; Gonzalez-Ramos, Daniel; Tabera, Laura; Gonzalez, Ramon

2010-04-30

Yeast mannoproteins are highly glycosylated proteins that are covalently bound to the beta-1,3-glucan present in the yeast cell wall. Among their outstanding enological properties, yeast mannoproteins contribute to several aspects of wine quality by protecting against protein haze, reducing astringency, retaining aroma compounds and stimulating growth of lactic-acid bacteria. The development of a non-recombinant method to obtain enological yeast strains overproducing mannoproteins would therefore be very useful. Our previous experience on the genetic determinants of the release of these molecules by Saccharomyces cerevisiae has allowed us to propose a new methodology to isolate and characterize wine yeast that overproduce mannoproteins. The described methodology is based on the resistance of the killer 9 toxin produced by Williopsis saturnus, a feature linked to an altered biogenesis of the yeast cell wall. Copyright 2010 Elsevier B.V. All rights reserved.
Biosorption of nickel by yeasts in an osmotically unsuitable environment.

PubMed

Breierová, Emilia; Certík, Milan; Kovárová, Annamaria; Gregor, Tomas

2008-01-01

The tolerance, sorption of nickel(II) ions, and changes in the production and composition of exopolymers of eight yeast strains grown under nickel presence with/without NaCl were studied. Strains of Pichia anomala and Candida maltosa known as the most resistant yeasts against nickel tolerated up to 3 mM Ni2+. NaCl addition decreased both the resistance of the yeast strains toward nickel ions and the sorption of metal ions into cells. All yeasts absorbed nickel predominantly into exopolymers (glycoproteins) and on the surface of cells. However, while the amount of polysaccharide moieties of exoglycoproteins of most of the resistant yeasts was induced by stress conditions, the ratio polysaccharide/protein in the exopolymers remained unchanged in the sensitive species Cystofilobasidium. The exopolymer composition might play a key role in yeast adaptation to stress conditions caused by heavy metal ions.
Genomic and Phenotypic Characterization of Yeast Biosensor for Deep-space Radiation

NASA Technical Reports Server (NTRS)

Marina, Diana B.; Santa Maria, Sergio; Bhattacharya, Sharmila

2016-01-01

The BioSentinel mission was selected to launch as a secondary payload onboard NASA Exploration Mission 1 (EM-1) in 2018. In BioSentinel, the budding yeast Saccharomyces cerevisiae will be used as a biosensor to measure the long-term impact of deep-space radiation to living organisms. In the 4U-payload, desiccated yeast cells from different strains will be stored inside microfluidic cards equipped with 3-color LED optical detection system to monitor cell growth and metabolic activity. At different times throughout the 12-month mission, these cards will be filled with liquid yeast growth media to rehydrate and grow the desiccated cells. The growth and metabolic rates of wild-type and radiation-sensitive strains in deep-space radiation environment will be compared to the rates measured in the ground- and microgravity-control units. These rates will also be correlated with measurements obtained from onboard physical dosimeters. In our preliminary long-term desiccation study, we found that air-drying yeast cells in 10% trehalose is the best method of cell preservation in order to survive the entire 18-month mission duration (6-month pre-launch plus 12-month full-mission periods). However, our study also revealed that desiccated yeast cells have decreasing viability over time when stored in payload-like environment. This suggests that the yeast biosensor will have different population of cells at different time points during the long-term mission. In this study, we are characterizing genomic and phenotypic changes in our yeast biosensor due to long-term storage and desiccation. For each yeast strain that will be part of the biosensor, several clones were reisolated after long-term storage by desiccation. These clones were compared to their respective original isolate in terms of genomic composition, desiccation tolerance and radiation sensitivity. Interestingly, clones from a radiation-sensitive mutant have better desiccation tolerance compared to their original isolate
Blastomyces dermatitidis septins CDC3, CDC10, and CDC12 impact the morphology of yeast and hyphae, but are not required for the phase transition.

PubMed

Marty, Amber J; Gauthier, Gregory M

2013-01-01

Blastomyces dermatitidis, the etiologic agent of blastomycosis, belongs to a group of thermally dimorphic fungi that change between mold (22°C) and yeast (37°C) in response to temperature. The contribution of structural proteins such as septins to this phase transition in these fungi remains poorly understood. Septins are GTPases that serve as a scaffold for proteins involved with cytokinesis, cell polarity, and cell morphology. In this study, we use a GFP sentinel RNA interference system to investigate the impact of CDC3, CDC10, CDC12, and ASPE on the morphology and phase transition of B. dermatitidis. Targeting CDC3, CDC10, and CDC12 by RNA interference resulted in yeast with aberrant morphology at 37°C with defects in cytokinesis. Downshifting the temperature to 22°C promoted the conversion to the mold phase, but did not abrogate the morphologic defects. CDC3, CDC10, and CDC12 knockdown strains grew as mold with curved, thickened hyphae. Knocking down ASPE transcript did not alter morphology of yeast at 37°C or mold at 22°C. Following an increase in temperature from 22°C to 37°C, all septin knockdown strains were able to revert to yeast. In conclusion, CDC3, CDC10, and CDC12 septin- encoding genes are required for proper morphology of yeast and hyphae, but are dispensable for the phase transition.
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 ...
Measurement of the volume growth rate of single budding yeast with the MOSFET-based microfluidic Coulter counter

PubMed Central

Sun, Jiashu; Stowers, Chris C.; Boczko, Erik M.

2012-01-01

We report on measurements of the volume growth rate of ten individual budding yeast cells using a recently developed MOSFET-based microfluidic Coulter counter. The MOSFET-based microfluidic Coulter counter is very sensitive, provides signals that are immune from the baseline drift, and can work with cell culture media of complex composition. These desirable features allow us to directly measure the volume growth rate of single cells of Saccharomyces cerevisiae LYH3865 strain budding yeast in YNB culture media over a whole cell cycle. Results indicate that all budding yeast follow a sigmoid volume growth profile with reduced growth rates at the initial stage before the bud emerges and the final stage after the daughter gets mature. Analysis of the data indicates that even though all piecewise linear, Gomperitz, and Hill’s function models can fit the global growth profile equally well, the data strongly support local exponential growth phenomenon. Accurate volume growth measurements are important for applications in systems biology where quantitative parameters are required for modeling and simulation. PMID:20717618
Measurement of the volume growth rate of single budding yeast with the MOSFET-based microfluidic Coulter counter.

PubMed

Sun, Jiashu; Stowers, Chris C; Boczko, Erik M; Li, Deyu

2010-11-07

We report on measurements of the volume growth rate of ten individual budding yeast cells using a recently developed MOSFET-based microfluidic Coulter counter. The MOSFET-based microfluidic Coulter counter is very sensitive, provides signals that are immune from the baseline drift, and can work with cell culture media of complex composition. These desirable features allow us to directly measure the volume growth rate of single cells of Saccharomyces cerevisiae LYH3865 strain budding yeast in YNB culture media over a whole cell cycle. Results indicate that all budding yeast follow a sigmoid volume growth profile with reduced growth rates at the initial stage before the bud emerges and the final stage after the daughter gets mature. Analysis of the data indicates that even though all piecewise linear, Gomperitz, and Hill's function models can fit the global growth profile equally well, the data strongly support local exponential growth phenomenon. Accurate volume growth measurements are important for applications in systems biology where quantitative parameters are required for modeling and simulation.
Yeast Reporter Assay to Identify Cellular Components of Ricin Toxin A Chain Trafficking.

PubMed

Becker, Björn; Schnöder, Tina; Schmitt, Manfred J

2016-12-06

RTA, the catalytic A-subunit of the ribosome inactivating A/B toxin ricin, inhibits eukaryotic protein biosynthesis by depurination of 28S rRNA. Although cell surface binding of ricin holotoxin is mainly mediated through its B-subunit (RTB), sole application of RTA is also toxic, albeit to a significantly lower extent, suggesting alternative pathways for toxin uptake and transport. Since ricin toxin trafficking in mammalian cells is still not fully understood, we developed a GFP-based reporter assay in yeast that allows rapid identification of cellular components required for RTA uptake and subsequent transport through a target cell. We hereby show that Ypt6p, Sft2p and GARP-complex components play an important role in RTA transport, while neither the retromer complex nor COPIB vesicles are part of the transport machinery. Analyses of yeast knock-out mutants with chromosomal deletion in genes whose products regulate ADP-ribosylation factor GTPases (Arf-GTPases) and/or retrograde Golgi-to-ER (endoplasmic reticulum) transport identified Sso1p, Snc1p, Rer1p, Sec22p, Erv46p, Gea1p and Glo3p as novel components in RTA transport, suggesting the developed reporter assay as a powerful tool to dissect the multistep processes of host cell intoxication in yeast.
Comparison of the effects of seleno-l-methionine, seleno-dl-methionine, and selenized yeast on reproduction of mallards

USGS Publications Warehouse

Heinz, G.H.; Hoffman, D.J.

1996-01-01

The toxicities of seleno-L-methionine, seleno-DL-methionine, and selenized yeast were compared. Ten pairs of mallards were fed a control diet and 15 pairs were fed diets containing 10 ppm selenium as seleno-DL-methionine, seleno-L-methionine, or selenized yeast. Hatching of fertile eggs was significantly lower for females fed 10 ppm selenium as seleno-DL-methionine (7.6%) and seleno-L-methionine (6.4%) than for controls (41.3%). Survival of ducklings was lower when their parents had been fed 10 ppm selenium as seleno-L-methionine (20.0%) than for controls (98.4%). The number of 6-day-old ducklings produced per female was significantly lower for mallards fed 10 ppm selenium as seleno-DL-methionine (0.47) or selenized yeast (2.67) than for controls (6.10), and was significantly lower for mallards fed seleno-L-methionine (0.13) than for mallards fed selenized yeast. The eighth eggs of females fed the DL or L forms of selenomethionine contained means of 9.2 and 8.9 ppm selenium, wet weight; these means were higher than the mean (6.6 ppm) for females fed selenized yeast. Among embryos that died at 7 days of age or older, the percentage of embryos that were deformed was 1.3% for controls, 24.6% for seleno-DL-methionine, 28.2% for seleno-L-methionine, and 11.0% for selenized yeast. The results suggested that seleno-DL-methionine and seleno-L-methionine were of similar toxicity and were both more toxic than selenium from selenized yeast.
Astaxanthinogenesis in the yeast Phaffia rhodozyma - optimization of low-cost culture media and yeast cell-wall lysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fontana, J.D.; Baron, M.; Guimaraes, M.F.

Astaxanthin is a diketo-dihydroxy-carotenoid produced by Phaffia rhodozyma, a basidiomicetous yeast. A low-cost fermentation medium consisting of raw sugarcane juice and urea was developed to exploit the active sucrolytic/urelolytic enzyme apparatus inherent to the yeast. As compared to the beneficial effect of 0.1 g% urea, a ready nitrogen source, mild phosphoric pre inversion of juice sucrose to glucose and fructose, promptly fermentable carbon sources, resulted in smaller benefits. Corn steep liquor (CSL) was found to be a valuable supplement for both yeast biomass yield (9.2 g dry cells/L) and astaxanthin production (1.3 mg/g cells). Distillery effluent (vinace), despite only amore » slightly positive effect on yeast growth, allowed for the highest pigment productivity (1.9 mg/g cells). Trace amounts of Ni{sup 2} (1 mg/L, as a cofactor for urease) resulted in controversial effects, namely, biomass decrease and astaxanthin increase, with no effect on the release (and uptake) of ammonium ion from urea. 13 refs., 6 figs.« less
The Candida albicans stress response gene Stomatin-Like Protein 3 is implicated in ROS-induced apoptotic-like death of yeast phase cells

PubMed Central

Salcedo, Eugenia C.

2018-01-01

The ubiquitous presence of SPFH (Stomatin, Prohibitin, Flotillin, HflK/HflC) proteins in all domains of life suggests that their function would be conserved. However, SPFH functions are diverse with organism-specific attributes. SPFH proteins play critical roles in physiological processes such as mechanosensation and respiration. Here, we characterize the stomatin ORF19.7296/SLP3 in the opportunistic human pathogen Candida albicans. Consistent with the localization of stomatin proteins, a Slp3p-Yfp fusion protein formed visible puncta along the plasma membrane. We also visualized Slp3p within the vacuolar lumen. Slp3p primary sequence analyses identified four putative S-palmitoylation sites, which may facilitate membrane localization and are conserved features of stomatins. Plasma membrane insertion sequences are present in mammalian and nematode SPFH proteins, but are absent in Slp3p. Strikingly, Slp3p was present in yeast cells, but was absent in hyphal cells, thus categorizing it as a yeast-phase specific protein. Slp3p membrane fluorescence significantly increased in response to cellular stress caused by plasma membrane, cell wall, oxidative, or osmotic perturbants, implicating SLP3 as a general stress-response gene. A slp3Δ/Δ homozygous null mutant had no detected phenotype when slp3Δ/Δ mutants were grown in the presence of a variety of stress agents. Also, we did not observe a defect in ion accumulation, filamentation, endocytosis, vacuolar structure and function, cell wall structure, or cytoskeletal structure. However, SLP3 over-expression triggered apoptotic-like death following prolonged exposure to oxidative stress or when cells were induced to form hyphae. Our findings reveal the cellular localization of Slp3p, and for the first time associate Slp3p function with the oxidative stress response. PMID:29389961
Get Ready, Get in, Get through: Factors That Influence Latino College Student Success

ERIC Educational Resources Information Center

Murphy, Joel P.; Murphy, Shirley A.

2018-01-01

"Get ready, get in, and get through." Latino adolescents and young adults are enrolling in the nation's colleges and universities at record numbers. However, completion rates of Latinos range from 8% to 25%. We examined individual rather than organizational factors shown to influence Latino student post-secondary levels of success.…
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. © 2013 The Author. Yeast Published by John Wiley & Sons Ltd.
Identification of She3 as an SCFGrr1 Substrate in Budding Yeast

PubMed Central

Wang, Ruiwen; Solomon, Mark J.

2012-01-01

The highly orchestrated progression of the cell cycle depends on the degradation of many regulatory proteins at different cell cycle stages. One of the key cell cycle ubiquitin ligases is the Skp1-cullin-F-box (SCF) complex. Acting in concert with the substrate-binding F-box protein Grr1, SCFGrr1 promotes the degradation of cell cycle regulators as well as various metabolic enzymes. Using a yeast two-hybrid assay with a Grr1 derivative as the bait, we identified She3, which is an adaptor protein in the asymmetric mRNA transport system, as a novel Grr1 substrate. We generated stabilized She3 mutants, which no longer bound to Grr1, and found that the degradation of She3 is not required for regulating asymmetric mRNA transport. However, She3 stabilization leads to slower growth compared to wild-type cells in a co-culture assay, demonstrating that the degradation of She3 by Grr1 is required for optimal cell growth. PMID:23144720
The presence of Enterococcus, coliforms and E. coli in a commercial yeast manufacturing process.

PubMed

O'Brien, S S; Lindsay, D; von Holy, A

2004-07-01

This study evaluated a typical commercial yeast manufacturing process for bacterial contamination. Product line samples of a commercial yeast manufacturing process and the corresponding seed yeast manufacturing process were obtained upstream from the final compressed and dry yeast products. All samples were analysed before (non-PI) and after preliminary incubation (PI) at 37 degrees C for 24 h. The PI procedure was incorporated for amplification of bacterial counts below the lower detection limit. Enterococcus, coliform and Escherichia coli counts were quantified by standard pour-plate techniques using selective media. Presence at all stages and progressive increases in counts of Enterococcus, coliforms and E. coli during processing in the commercial manufacturing operation suggested that the primary source of contamination of both compressed and dry yeast with these bacteria was the seed yeast manufacturing process and that contamination was amplified throughout the commercial yeast manufacturing process. This was confirmed by surveys of the seed yeast manufacturing process which indicated that contamination of the seed yeast with Enterococcus, coliforms and E. coli occurred during scale up of seed yeast biomass destined as inoculum for the commercial fermentation.
Marine yeast isolation and industrial application.

PubMed

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

2014-09-01

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. © 2014 The Authors FEMS Yeast Research published by John Wiley & Sons Ltd on behalf of Federation of European Microbiological Societies.
Competitive advantage and tolerance of selected shochu yeast in barley shochu mash.

PubMed

Takashita, Hideharu; Fujihara, Emi; Furutera, Mihoko; Kajiwara, Yasuhiro; Shimoda, Masahiko; Matsuoka, Masayoshi; Ogawa, Takahira; Kawamoto, Seiji; Ono, Kazuhisa

2013-07-01

A shochu yeast strain, Saccharomyces cerevisiae BAW-6, was previously isolated from Kagoshima yeast strain Ko, and has since been utilized in shochu production. The BAW-6 strain carries pho3/pho3 homozygous genes in contrast to the heterozygous PHO3/pho3 genes in the parental Ko strain. However, absence of the PHO3 gene per se cannot explain the fermentation superiority of BAW-6. Here, we demonstrate the growth advantage of the BAW-6 strain over the Ko strain by competitive cultivation in barley shochu preparation, where alcohol yield and nihonshudo of the former strain were higher than those of the latter strain. In addition, the maximum growth rate of BAW-6 was less affected than that of Ko by high Brix values of barley koji medium, suggesting that BAW-6 is less sensitive to growth inhibitory compounds derived from barley or barley koji. The tolerance of BAW-6 to growth inhibitory compounds, cerulenin and diethylstilbestrol (an H⁺-ATPase inhibitor), was also higher than that of other yeast strains. Consistent with BAW-6's tolerance to diethylstilbestrol in the presence of 8% ethanol (pH 4.5), H⁺-ATPase activity, but not transcription of its gene, was higher in BAW-6 than in Ko. We conclude that the BAW-6 strain is associated with certain gene alterations other than PHO3, such that it can maintain cellular ion homeostasis under conditions of ethanol stress during the latter phase of fermentation. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.
Yeast: An Overlooked Component of Bactrocera tryoni (Diptera: Tephritidae) Larval Gut Microbiota.

PubMed

Deutscher, Ania T; Reynolds, Olivia L; Chapman, Toni A

2017-02-01

Yeasts, often in hydrolyzed form, are key ingredients in the larval and adult diets of tephritid fruit fly colonies. However, very little is known about the presence or role of yeasts in the diets of tephritid fruit flies in nature. Previous studies have identified bacteria but not detected yeasts in the gut of Queensland fruit fly, Bactrocera tryoni (Froggatt), one of Australia's most economically damaging insect pests of horticultural crops and of significant biosecurity concern domestically and internationally. Here we demonstrate that cultivable yeasts are commonly found in the gut of B. tryoni larvae from fruit hosts. Analysis of the ITS1, 5.8S rRNA gene, and ITS2 sequences of randomly selected isolates identified yeasts and yeast-like fungi of the genera Aureobasidium, Candida, Cryptococcus, Hanseniaspora, Pichia, and Starmerella. The prevalence of these yeasts in fruits suggests that larvae consume the yeasts as part of their diet. This work highlights that yeasts should be considered in future tephritid larval gut microbiota studies. Understanding tephritid-microbial symbiont interactions will lead to improvements in artificial diets and the quality of mass-reared tephritids for the sterile insect technique. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
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.

Single-particle tracking of quantum dot-conjugated prion proteins inside yeast cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsuji, Toshikazu; Kawai-Noma, Shigeko; Pack, Chan-Gi

2011-02-25

Research highlights: {yields} We develop a method to track a quantum dot-conjugated protein in yeast cells. {yields} We incorporate the conjugated quantum dot proteins into yeast spheroplasts. {yields} We track the motions by conventional or 3D tracking microscopy. -- Abstract: Yeast is a model eukaryote with a variety of biological resources. Here we developed a method to track a quantum dot (QD)-conjugated protein in the budding yeast Saccharomyces cerevisiae. We chemically conjugated QDs with the yeast prion Sup35, incorporated them into yeast spheroplasts, and tracked the motions by conventional two-dimensional or three-dimensional tracking microscopy. The method paves the way towardmore » the individual tracking of proteins of interest inside living yeast cells.« less
Characterization of Hyaluronan-Degrading Enzymes from Yeasts.

PubMed

Smirnou, Dzianis; Krčmář, Martin; Kulhánek, Jaromír; Hermannová, Martina; Bobková, Lenka; Franke, Lukáš; Pepeliaev, Stanislav; Velebný, Vladimír

2015-10-01

Hyaluronidases (HAases) from yeasts were characterized for the first time. The study elucidated that hyaluronate 4-glycanohydrolase and hyaluronan (HA) lyase can be produced by yeasts. Six yeasts producing HAases were found through express screening of activities. The extracellular HAases from two of the yeast isolates, Pseudozyma aphidis and Cryptococcus laurentii, were characterized among them. P. aphidis HAase hydrolyzed β-1,4 glycosidic bonds of HA, yielding even-numbered oligosaccharides with N-acetyl-D-glucosamine at the reducing end. C. laurentii produced hyaluronan lyase, which cleaved β-1,4 glycosidic bonds of HA in β-elimination reaction, and the products of HA degradation were different-sized even-numbered oligosaccharides. The shortest detected HA oligomer was dimer. The enzymes' pH and temperature optima were pH 3.0 and 37-45 °C (P. aphidis) and pH 6.0 and 37 °C (C. laurentii), respectively. Both HAases showed good thermostability.
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
The Putative Exchange Factor Gef3p Interacts with Rho3p GTPase and the Septin Ring during Cytokinesis in Fission Yeast*

PubMed Central

Muñoz, Sofía; Manjón, Elvira; Sánchez, Yolanda

2014-01-01

The small GTP-binding proteins of the Rho family and its regulatory proteins play a central role in cytokinetic actomyosin ring assembly and cytokinesis. Here we show that the fission yeast guanine nucleotide exchange factor Gef3p interacts with Rho3p at the division site. Gef3p contains a putative DH homology domain and a BAR/IMD-like domain. The protein localized to the division site late in mitosis, where it formed a ring that did not constrict with actomyosin ring (cytokinetic actomyosin ring) invagination; instead, it split into a double ring that resembled the septin ring. Gef3p co-localized with septins and Mid2p and required septins and Mid2p for its localization. Gef3p interacts physically with the GTP-bound form of Rho3p. Although Gef3p is not essential for cell separation, the simultaneous disruption of gef3+ and Rho3p-interacting proteins, such as Sec8p, an exocyst component, Apm1p, a subunit of the clathrin adaptor complex or For3p, an actin-polymerizing protein, yielded cells with strong defects in septation and polarity respectively. Our results suggest that interactions between septins and Rho-GEFs provide a new targeting mechanism for GTPases in cytokinesis, in this case probably contributing to Rho3p function in vesicle tethering and vesicle trafficking in the later steps of cell separation. PMID:24947517
Interaction between lactic acid bacteria and yeasts in airag, an alcoholic fermented milk.

PubMed

Sudun; Wulijideligen; Arakawa, Kensuke; Miyamoto, Mari; Miyamoto, Taku

2013-01-01

The interaction between nine lactic acid bacteria (LAB) and five yeast strains isolated from airag of Inner Mongolia Autonomic Region, China was investigated. Three representative LAB and two yeasts showed symbioses were selected and incubated in 10% (w/v) reconstituted skim milk as single and mixed cultures to measure viable count, titratable acidity, ethanol and sugar content every 24 h for 1 week. LAB and yeasts showed high viable counts in the mixed cultures compared to the single cultures. Titratable acidity of the mixed cultures was obviously enhanced compared with that of the single cultures, except for the combinations of Lactobacillus reuteri 940B3 with Saccharomyces cerevisiae 4C and Lactobacillus helveticus 130B4 with Candida kefyr 2Y305. C. kefyr 2Y305 produced large amounts of ethanol (maximum 1.35 g/L), whereas non-lactose-fermenting S. cerevisiae 4C produced large amounts of ethanol only in the mixed cultures. Total glucose and galactose content increased while lactose content decreased in the single cultures of Leuconostoc mesenteroides 6B2081 and Lb. helveticus 130B4. However, both glucose and galactose were completely consumed and lactose was markedly reduced in the mixed cultures with yeasts. The result suggests that yeasts utilize glucose and galactose produced by LAB lactase to promote cell growth. © 2012 The Authors. Animal Science Journal © 2012 Japanese Society of Animal Science.
Brewers dried yeast as a source of mannan oligosaccharides for weanling pigs.

PubMed

White, L A; Newman, M C; Cromwell, G L; Lindemann, M D

2002-10-01

Brewers dried yeast, a source of mannan oligosaccharides (MOS), was assessed as an alternative to an antimicrobial agent (carbadox) for young pigs in two experiments. The yeast contained 5.2% MOS. Agglutination tests confirmed adsorption of several serovars of E. coli and Salmonella spp. onto the yeast product. In Exp. 1, seven replicates (five pigs per pen) of 22-d-old pigs were fed a nonmedicated basal diet or the basal diet with carbadox (55 mg/kg), yeast (3%), or a combination of 3% yeast and 2% citric acid for 28 d. Carbadox did not improve growth performance. Growth rate and feed intake were depressed (P < 0.05) in pigs fed yeast alone or in combination with acid. Log counts of total coliforms, Escherichia coli, and Clostridium perfringens in feces were not affected by diet, but Bifidobacteria spp. counts were lower (P < 0.05) in pigs fed the yeast + acid diet and lactobacilli counts were higher (P < 0.05) in pigs fed yeast. Fecal pH and VFA concentrations and intestinal morphological traits were not consistently affected by diet. Serum IgG levels were elevated in the yeast + acid (P < 0.01) group. In Exp. 2, the effects of yeast and carbadox additions to the diet on enteric microbial populations in young pigs housed in isolation units were evaluated. Pigs (n = 24) were weaned at 11 d of age (4.1 kg BW) and placed in isolation chambers (two pigs per chamber) equipped with individual air filtering systems and excrement containers. Treatments were a nonmedicated basal diet and the basal diet with 55 mg/kg of carbadox or with 3% yeast. Diets were fed for 29 d, then each pig was orally dosed with approximately 9.5 x 10(8) CFU of E. coli K88. Daily fecal E. coli K88 counts were not different (P > 0.05) among treatments, but fecal shedding of carbadox-resistant coliforms was higher (P < 0.01) during the 9-d period in pigs fed carbadox. Total fecal coliforms were consistently lower throughout the postinoculation period in pigs fed yeast (P < 0.05). Yeast reduced
A prolonged chronological lifespan is an unexpected benefit of the [PSI+] prion in yeast.

PubMed

Wang, Kai; Melki, Ronald; Kabani, Mehdi

2017-01-01

Self-replicating 'proteinaceous infectious particles' or prions are responsible for complex heritable traits in the yeast Saccharomyces cerevisiae. Our current understanding of the biology of yeast prions stems from studies mostly done in the context of actively dividing cells in optimal laboratory growth conditions. Evidence suggest that fungal prions exist in the wild where most cells are in a non-dividing quiescent state, because of imperfect growth conditions, scarcity of nutrients and competition. We know little about the faithful transmission of yeast prions in such conditions and their physiological consequences throughout the lifespan of yeast cells. We addressed this issue for the [PSI+] prion that results from the self-assembly of the translation release factor Sup35p into insoluble fibrillar aggregates. [PSI+] leads to increased nonsense suppression and confers phenotypic plasticity in response to environmental fluctuations. Here, we report that while [PSI+] had little to no effect on growth per se, it dramatically improved the survival of yeast cells in stationary phase. Remarkably, prolonged chronological lifespan persisted even after [PSI+] was cured from the cells, suggesting that prions may facilitate the acquisition of complex new traits. Such an important selective advantage may contribute to the evolutionary conservation of the prion-forming ability of Sup35p orthologues in distantly related yeast species.
Internal amino acid state modulates yeast taste neurons to support protein homeostasis in Drosophila

PubMed Central

Itskov, Pavel M; Baltazar, Célia; Moreira, José-Maria

2018-01-01

To optimize fitness, animals must dynamically match food choices to their current needs. For drosophilids, yeast fulfills most dietary protein and micronutrient requirements. While several yeast metabolites activate known gustatory receptor neurons (GRNs) in Drosophila melanogaster, the chemosensory channels mediating yeast feeding remain unknown. Here we identify a class of proboscis GRNs required for yeast intake. Within this class, taste peg GRNs are specifically required to sustain yeast feeding. Sensillar GRNs, however, mediate feeding initiation. Furthermore, the response of yeast GRNs, but not sweet GRNs, is enhanced following deprivation from amino acids, providing a potential basis for protein-specific appetite. Although nutritional and reproductive states synergistically increase yeast appetite, reproductive state acts independently of nutritional state, modulating processing downstream of GRNs. Together, these results suggest that different internal states act at distinct levels of a dedicated gustatory circuit to elicit nutrient-specific appetites towards a complex, ecologically relevant protein source. PMID:29393045
Metabolic Engineering of Oleaginous Yeasts for Production of Fuels and Chemicals

PubMed Central

Shi, Shuobo; Zhao, Huimin

2017-01-01

Oleaginous yeasts have been increasingly explored for production of chemicals and fuels via metabolic engineering. Particularly, there is a growing interest in using oleaginous yeasts for the synthesis of lipid-related products due to their high lipogenesis capability, robustness, and ability to utilize a variety of substrates. Most of the metabolic engineering studies in oleaginous yeasts focused on Yarrowia that already has plenty of genetic engineering tools. However, recent advances in systems biology and synthetic biology have provided new strategies and tools to engineer those oleaginous yeasts that have naturally high lipid accumulation but lack genetic tools, such as Rhodosporidium, Trichosporon, and Lipomyces. This review highlights recent accomplishments in metabolic engineering of oleaginous yeasts and recent advances in the development of genetic engineering tools in oleaginous yeasts within the last 3 years. PMID:29167664
Metabolic Engineering of Oleaginous Yeasts for Production of Fuels and Chemicals.

PubMed

Shi, Shuobo; Zhao, Huimin

2017-01-01

Oleaginous yeasts have been increasingly explored for production of chemicals and fuels via metabolic engineering. Particularly, there is a growing interest in using oleaginous yeasts for the synthesis of lipid-related products due to their high lipogenesis capability, robustness, and ability to utilize a variety of substrates. Most of the metabolic engineering studies in oleaginous yeasts focused on Yarrowia that already has plenty of genetic engineering tools. However, recent advances in systems biology and synthetic biology have provided new strategies and tools to engineer those oleaginous yeasts that have naturally high lipid accumulation but lack genetic tools, such as Rhodosporidium , Trichosporon , and Lipomyces . This review highlights recent accomplishments in metabolic engineering of oleaginous yeasts and recent advances in the development of genetic engineering tools in oleaginous yeasts within the last 3 years.
Nectar-living yeasts of a tropical host plant community: diversity and effects on community-wide floral nectar traits

PubMed Central

2017-01-01

We characterize the diversity of nectar-living yeasts of a tropical host plant community at different hierarchical sampling levels, measure the associations between yeasts and nectariferous plants, and measure the effect of yeasts on nectar traits. Using a series of hierarchically nested sampling units, we extracted nectar from an assemblage of host plants that were representative of the diversity of life forms, flower shapes, and pollinator types in the tropical area of Yucatan, Mexico. Yeasts were isolated from single nectar samples; their DNA was identified, the yeast cell density was estimated, and the sugar composition and concentration of nectar were quantified using HPLC. In contrast to previous studies from temperate regions, the diversity of nectar-living yeasts in the plant community was characterized by a relatively high number of equally common species with low dominance. Analyses predict highly diverse nectar yeast communities in a relatively narrow range of tropical vegetation, suggesting that the diversity of yeasts will increase as the number of sampling units increases at the level of the species, genera, and botanical families of the hosts. Significant associations between specific yeast species and host plants were also detected; the interaction between yeasts and host plants impacted the effect of yeast cell density on nectar sugars. This study provides an overall picture of the diversity of nectar-living yeasts in tropical host plants and suggests that the key factor that affects the community-wide patterns of nectar traits is not nectar chemistry, but rather the type of yeasts interacting with host plants. PMID:28717591
Chemical Synthesis of Sulfated Yeast (Saccharomyces cerevisiae) Glucans and Their In Vivo Antioxidant Activity.

PubMed

Zhang, Hua; Zhang, Jing; Fan, Ziluan; Zhou, Xintao; Geng, Lin; Wang, Zhenyu; Regenstein, Joe M; Xia, Zhiqiang

2017-07-28

The effects of sulfation of yeast glucans was optimized using response surface methodology. The degree of sulfation was evaluated from 0.11 to 0.75 using ion-chromatography. The structural characteristics of SYG (sulfation of yeast glucans) with a DS = 0.75 were determined using high-performance liquid chromatography/gel-permeation chromatography and finally by Fourier transform infrared spectrometry. The SYG had lower viscosity and greater solubility than the native yeast glucans, suggesting that the conformation of the SYG had significantly changed. The results also showed that SYG had a significantly greater antioxidant activity in vivo compared to native yeast glucans.
[Yeast microbiota in artisanal cheeses from Corrientes, Argentina].

PubMed

Cardozo, Marina C; Fusco, Ángel J V; Carrasco, Marta S

The artisanal cheese from Corrientes (from the Spanish acronym QAC-Queso Artesanal de Corrientes/Artisanal Cheese from Corrientes) is a soft cheese elaborated with raw cow milk and an artisanal coagulant agent. Lactic bacteria contitute the main flora of this cheese although yeasts are also present in high quantities as secondary microbiota and might play a relevant role in cheese ripening. The aim of this work was to evaluate yeast occurrence during QAC elaboration and ripening, and the effect of seasonal variation. Yeasts were isolated and purified from raw materials and cheese at different ripening stagesl elaborated during the different seasons. Yeast sample counts were in the order of 10 3 - 10 7 UFC/ml o UFC/g. Ninety yeast strains were classified: 9 from milk, 28 from the coagulant agent, 10 from curd and 43 from cheese. Candida predominated in milk samples while other yeast genera had low incidence. Candida also predominated in the coagulant agent samples, followed by genera Myxozyma and Debaryomyces. The isolates obtained from cheese belonged to the same genera predominating in the coagulant agent, and showed the same order of prevalence. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.
Mutations in the Atp1p and Atp3p subunits of yeast ATP synthase differentially affect respiration and fermentation in Saccharomyces cerevisiae.

PubMed

Francis, Brian R; White, Karen H; Thorsness, Peter E

2007-04-01

ATP1-111, a suppressor of the slow-growth phenotype of yme1Delta lacking mitochondrial DNA is due to the substitution of phenylalanine for valine at position 111 of the alpha-subunit of mitochondrial ATP synthase (Atp1p in yeast). The suppressing activity of ATP1-111 requires intact beta (Atp2p) and gamma (Atp3p) subunits of mitochondrial ATP synthase, but not the stator stalk subunits b (Atp4p) and OSCP (Atp5p). ATP1-111 and other similarly suppressing mutations in ATP1 and ATP3 increase the growth rate of wild-type strains lacking mitochondrial DNA. These suppressing mutations decrease the growth rate of yeast containing an intact mitochondrial chromosome on media requiring oxidative phosphorylation, but not when grown on fermentable media. Measurement of chronological aging of yeast in culture reveals that ATP1 and ATP3 suppressor alleles in strains that contain mitochondrial DNA are longer lived than the isogenic wild-type strain. In contrast, the chronological life span of yeast cells lacking mitochondrial DNA and containing these mutations is shorter than that of the isogenic wild-type strain. Spore viability of strains bearing ATP1-111 is reduced compared to wild type, although ATP1-111 enhances the survival of spores that lacked mitochondrial DNA.
Quasi-programmed aging of budding yeast: a trade-off between programmed processes of cell proliferation, differentiation, stress response, survival and death defines yeast lifespan

PubMed Central

Arlia-Ciommo, Anthony; Piano, Amanda; Leonov, Anna; Svistkova, Veronika; Titorenko, Vladimir I

2014-01-01

Recent findings suggest that evolutionarily distant organisms share the key features of the aging process and exhibit similar mechanisms of its modulation by certain genetic, dietary and pharmacological interventions. The scope of this review is to analyze mechanisms that in the yeast Saccharomyces cerevisiae underlie: (1) the replicative and chronological modes of aging; (2) the convergence of these 2 modes of aging into a single aging process; (3) a programmed differentiation of aging cell communities in liquid media and on solid surfaces; and (4) longevity-defining responses of cells to some chemical compounds released to an ecosystem by other organisms populating it. Based on such analysis, we conclude that all these mechanisms are programs for upholding the long-term survival of the entire yeast population inhabiting an ecological niche; however, none of these mechanisms is a ʺprogram of agingʺ - i.e., a program for progressing through consecutive steps of the aging process. PMID:25485579
Wine yeasts for the future.

PubMed

Fleet, Graham H

2008-11-01

International competition within the wine market, consumer demands for newer styles of wines and increasing concerns about the environmental sustainability of wine production are providing new challenges for innovation in wine fermentation. Within the total production chain, the alcoholic fermentation of grape juice by yeasts is a key process where winemakers can creatively engineer wine character and value through better yeast management and, thereby, strategically tailor wines to a changing market. This review considers the importance of yeast ecology and yeast metabolic reactions in determining wine quality, and then discusses new directions for exploiting yeasts in wine fermentation. It covers criteria for selecting and developing new commercial strains, the possibilities of using yeasts other than those in the genus of Saccharomyces, the prospects for mixed culture fermentations and explores the possibilities for high cell density, continuous fermentations.
Immobilised Sarawak Malaysia yeast cells for production of bioethanol.

PubMed

Zain, Masniroszaime Mohd; Kofli, Noorhisham Tan; Rozaimah, Siti; Abdullah, Sheikh

2011-05-01

Bioethanol production using yeast has become a popular topic due to worrying depleting worldwide fuel reserve. The aim of the study was to investigate the capability of Malaysia yeast strains isolated from starter culture used in traditional fermented food and alcoholic beverages in producing Bioethanol using alginate beads entrapment method. The starter yeast consists of groups of microbes, thus the yeasts were grown in Sabouraud agar to obtain single colony called ST1 (tuak) and ST3 (tapai). The growth in Yeast Potatoes Dextrose (YPD) resulted in specific growth of ST1 at micro = 0.396 h-1 and ST3 at micro = 0.38 h-1, with maximum ethanol production of 7.36 g L-1 observed using ST1 strain. The two strains were then immobilized using calcium alginate entrapment method producing average alginate beads size of 0.51 cm and were grown in different substrates; YPD medium and Local Brown Sugar (LBS) for 8 h in flask. The maximum ethanol concentration measured after 7 h were at 6.63 and 6.59 g L-1 in YPD media and 1.54 and 1.39 g L-1in LBS media for ST1 and ST3, respectively. The use of LBS as carbon source showed higher yield of product (Yp/s), 0.59 g g-1 compared to YPD, 0.25 g g-1 in ST1 and (Yp/s), 0.54 g g-1 compared to YPD, 0.24 g g-1 in ST3 . This study indicated the possibility of using local strains (STI and ST3) to produce bioethanol via immobilization technique with local materials as substrate.
New family of pectinase genes PGU1b-PGU3b of the pectinolytic yeast Saccharomyces bayanus var. uvarum.

PubMed

Naumov, G I; Shalamitskiy, M Yu; Naumova, E S

2016-03-01

Using yeast genome databases and literature data, we have conducted a phylogenetic analysis of pectinase PGU genes from Saccharomyces strains assigned to the biological species S. arboricola, S. bayanus (var. uvarum), S. cariocanus, S. cerevisiae, S. kudriavzevii, S. mikatae, S. paradoxus, and hybrid taxon S. pastorianus (syn. S. carlsbergensis). Single PGU genes were observed in all Saccharomyces species, except S. bayanus. The superfamily of divergent PGU genes has been documented in S. bayanus var. uvarum for the first time. Chromosomal localization of new PGU1b, PGU2b, and PGU3b genes in the yeast S. bayanus var. uvarum has been determined by molecular karyotyping and Southern hybridization.
Isolation of Yeasts from Guajillo Pepper (Capsicum annuum L.) Fermentation and Study of Some Probiotic Characteristics.

PubMed

Lara-Hidalgo, C E; Dorantes-Álvarez, L; Hernández-Sánchez, H; Santoyo-Tepole, F; Martínez-Torres, A; Villa-Tanaca, L; Hernández-Rodríguez, C

2018-04-25

Three yeast strains were isolated from the spontaneous fermentation of guajillo pepper: Hanseniaspora opuntiae, Pichia kudriavzevii, and Wickerhamomyces anomalus, which were identified by amplification of the ITS/5.8S ribosomal DNA. Some probiotic characteristics of these strains were evaluated and compared with one commercial probiotic yeast (Saccharomyces boulardii). The survival percentage of all the yeasts was similar to that of the commercial product. They showed different hydrophobicity characteristics with hydrocarbons, autoaggregation > 90%, and characteristics of co-aggregation with pathogenic microorganisms. The adhesion capacity to mucin of the three yeast samples was similar to the reference yeast. The antioxidant activity of the yeasts varied between 155 and 178 μM Trolox equivalents. All exhibited cholesterol reduction capacity, and W. anomalus was able to decrease up to 83% of cholesterol after 48 h of incubation. The 7.5-fold concentrated H. opuntiae supernatant had antimicrobial activity against Salmonella enterica ser. Typhimurium ATCC 14028 and Candida albicans ENCBDM2; tests suggest this activity against S. Typhimurium is due to a proteinaceous metabolite with a weight between 10 and 30 kDa. Among the yeasts, P. kudriavzevii exhibited the highest protective effect on the viability of Lactobacillus casei Shirota in gastric and intestinal conditions. These results suggest that yeasts isolated from guajillo pepper may have a probiotic potential.
Tolerant industrial yeast Saccharomyces cerevisiae posses a more robust cell wall integrity signaling pathway against 2-furaldehyde and 5-(hydroxymethyl)-2-furaldehyde.

PubMed

Liu, Z Lewis; Wang, Xu; Weber, Scott A

2018-06-20

Cell wall integrity signaling pathway in Saccharomyces cerevisiae is a conserved function for detecting and responding to cell stress conditions but less understood for industrial yeast. We examined gene expression dynamics for a tolerant industrial yeast strain NRRL Y-50049 in response to challenges of furfural and HMF through comparative quantitative gene expression analysis using pathway-based qRT-PCR array assays. All tested genes from Y-50049, except for MLP2, demonstrated more resistant and significantly increased gene expression than that from a laboratory strain BY4741. While all five sensor encoding genes WSC1, WSC2, WSC3, MID2 and MTL1 from both strains were activated in response to the furfural-HMF treatment, WSC3 from Y-50049 demonstrated the most increased expression over time compared with any other sensor genes. These results suggested the industrial yeast poses more robust cell wall integrity pathway, and gene WSC3 could have the special capability for signal transmission against furfural and HMF. Among five single nucleotide variations discovered in WSC3 from Y-50049, three were found to be non-synonymous mutations resulting in amino acid alterations of Ser 158  → Tyr 158 , Val 186  → Ile 186 , and Glu 430  → Asp 430 . Our results suggest the industrial yeast as a more desirable delivery vehicle for the next-generation biocatalyst development. Published by Elsevier B.V.

Stable current outputs and phytate degradation by yeast-based biofuel cell.

PubMed

Hubenova, Yolina; Georgiev, Danail; Mitov, Mario

2014-09-01

In this paper, we report for the first time that Candida melibiosica 2491 yeast strain expresses enhanced phytase activity when used as a biocatalyst in biofuel cells. The polarization also results in an increase of the yeast biomass. Higher steady-state electrical outputs, assigned to earlier production of an endogenous mediator, were achieved at continuous polarization under constant load. The obtained results prove that the C. melibiosica yeast-based biofuel cell could be used for simultaneous electricity generation and phytate bioremediation. In addition, the higher phytase activity obtained by interruptive polarization suggests a new method for increasing the phytase yield from microorganisms. Copyright © 2014 John Wiley & Sons, Ltd.
[Antivirus effect of polysaccharides of brewer yeast in vitro].

PubMed

Li, F; Shi, Y; Guan, X; Zhang, S; Tian, T

1998-03-01

The antivirus effect of polysaccharides of brewer yeast from yeast mud on 13 kinds of viruses including DNA and RNA virus along with their mechanisms were studied. The result showed that this effect was remarkable on the infections with poliovirus III, adenovirus III, ECHO6 virus, enterovirus 71, vesicular stomatitis virus, herpesvirus I, II, coxsackie A16 virus and coxsackie B3 virus. The polysaccharides of brewer yeast could also inhibit the development of cytopathic effect(CPE) and protect cultural cells from being infected with the above viruses.
Yeasts as important agents of onychomycosis: in vitro activity of propolis against yeasts isolated from patients with nail infection.

PubMed

Khosravi, Ali Reza; Shokri, Hojjatollah; Nikaein, Donya; Mansouri, Parvin; Erfanmanesh, Ahmad; Chalangari, Reza; Katalin, Martis

2013-01-01

The purposes of this study were to determine the frequency of the yeast species obtained from patients with clinical features of onychomycosis and the in vitro antifungal susceptibility of the yeast species to propolis. A prospective study was carried out at the Mycology Research Center in Iran from 2010 to 2011. Clinical diagnosis was performed by direct microscopic examination and culture. Different yeast species were identified by morphological and biochemical tests. An antifungal susceptibility test to fluconazole (FLU) and propolis by the broth microdilution method was performed on each isolate. One hundred and twenty-eight fungal isolates were obtained. The most prevalent fungi were yeasts (81, 63.2%), dermatophytes (36, 28.1%), and nondermatophyte fungi (11, 8.6%). Fingernails were more affected than toenails (65.4% vs. 19.8%, respectively). The most frequently found species was Candida albicans (38.5%), followed by Candida spp. (23.1%), C. tropicalis (10.8%), C. kefyr (6.2%), C. krusei (3.1%), Malassezia globosa (4.6%), M. slooffiae (4.6%), and M. pachydermatis (1.5%). Of all yeast isolates (65), seven showed resistance to FLU. The average MIC of propolis for FLU-susceptible isolates was 5.8 μg/mL, whereas this value was 12.25 μg/mL for FLU-resistant isolates. Our results proved that the propolis inhibits the growth of pathogenic yeasts and confirmed the efficiency of propolis as an anti-Candida and anti-Malassezia agent.
SH3 interactome conserves general function over specific form

PubMed Central

Xin, Xiaofeng; Gfeller, David; Cheng, Jackie; Tonikian, Raffi; Sun, Lin; Guo, Ailan; Lopez, Lianet; Pavlenco, Alevtina; Akintobi, Adenrele; Zhang, Yingnan; Rual, Jean-François; Currell, Bridget; Seshagiri, Somasekar; Hao, Tong; Yang, Xinping; Shen, Yun A; Salehi-Ashtiani, Kourosh; Li, Jingjing; Cheng, Aaron T; Bouamalay, Dryden; Lugari, Adrien; Hill, David E; Grimes, Mark L; Drubin, David G; Grant, Barth D; Vidal, Marc; Boone, Charles; Sidhu, Sachdev S; Bader, Gary D

2013-01-01

Src homology 3 (SH3) domains bind peptides to mediate protein–protein interactions that assemble and regulate dynamic biological processes. We surveyed the repertoire of SH3 binding specificity using peptide phage display in a metazoan, the worm Caenorhabditis elegans, and discovered that it structurally mirrors that of the budding yeast Saccharomyces cerevisiae. We then mapped the worm SH3 interactome using stringent yeast two-hybrid and compared it with the equivalent map for yeast. We found that the worm SH3 interactome resembles the analogous yeast network because it is significantly enriched for proteins with roles in endocytosis. Nevertheless, orthologous SH3 domain-mediated interactions are highly rewired. Our results suggest a model of network evolution where general function of the SH3 domain network is conserved over its specific form. PMID:23549480
Discussion of teleomorphic and anamorphic Ascomycetous yeasts and yeast-like taxa

USDA-ARS?s Scientific Manuscript database

The relationship of ascomycetous yeasts with other members of the ascomycete fungi (Ascomycota) has been controversial for over 100 years. Because yeasts are morphologically simple, it was proposed that they represent primitive forms of ascomycetes (e.g., Guilliermond 1912). Alternatively, the ide...
Recombinant yeast with improved ethanol tolerance and related methods of use

DOEpatents

Gasch, Audrey P [Madison, WI; Lewis, Jeffrey A [Madison, WI

2012-05-15

The present invention provides isolated Elo1 and Mig3 nucleic acid sequences capable of conferring increased ethanol tolerance on recombinant yeast and methods of using same in biofuel production, particularly ethanol production. Methods of bioengineering yeast using the Elo1 and, or, Mig3 nucleic acid sequences are also provided.
The plant homeodomain fingers of fission yeast Msc1 exhibit E3 ubiquitin ligase activity.

PubMed

Dul, Barbara E; Walworth, Nancy C

2007-06-22

The DNA damage checkpoint pathway governs how cells regulate cell cycle progression in response to DNA damage. A screen for suppressors of a fission yeast chk1 mutant defective in the checkpoint pathway identified a novel Schizosaccharomyces pombe protein, Msc1. Msc1 contains 3 plant homeodomain (PHD) finger motifs, characteristically defined by a C4HC3 consensus similar to RING finger domains. PHD finger domains in viral proteins and in the cellular protein kinase MEKK1 (mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase 1) have been implicated as ubiquitin E3 protein ligases that affect protein stability. The close structural relationship of PHD fingers to RING fingers suggests that other PHD domain-containing proteins might share this activity. We show that each of the three PHD fingers of Msc1 can act as ubiquitin E3 ligases, reporting for the first time that PHD fingers from a nuclear protein exhibit E3 ubiquitin ligase activity. The function of the PHD fingers of Msc1 is needed to rescue the DNA damage sensitivity of a chk1Delta strain. Msc1 co-precipitates Rhp6, the S. pombe homologue of the human ubiquitin-conjugating enzyme Ubc2. Strikingly, deletion of msc1 confers complete suppression of the slow growth phenotype, UV and hydroxyurea sensitivities of an rhp6 deletion strain and restores deficient histone H3 methylation observed in the rhp6Delta mutant. We speculate that the target of the E3 ubiquitin ligase activity of Msc1 is likely to be a chromatin-associated protein.
Chitosan inactivates spoilage yeasts but enhances survival of Escherichia coli O157:H7 in apple juice.

PubMed

Kiskó, G; Sharp, R; Roller, S

2005-01-01

To develop new measures for controlling both spoilage and pathogenic micro-organisms in unpasteurized apple juice using chitosan. Micro-organisms were isolated and identified from apple juice treated or untreated with chitosan using enrichment, selective media, microscopy, substrate assimilation patterns and ribosomal DNA profiling. Chitosan (0.05-0.1%) delayed spoilage by yeasts at 25 degrees C for up to 12 days but the effect was species specific: Kloeckera apiculata and Metschnikowia pulcherrima were inactivated but Saccharomyces cerevisiae and Pichia spp. multiplied slowly. In challenge experiments at 25 degrees C, total yeast counts were 3-5 log CFU ml(-1) lower in chitosan-treated juices than in the controls for 4 days but the survival of Escherichia coli O157:H7 was extended from 1 to 2 days; at 4 degrees C, chitosan reduced the yeast counts by 2-3 log CFU ml(-1) for up to 10 days but survival of the pathogen was prolonged from 3 to 5 days. The survival of Salmonella enterica serovar Typhimurium was unaffected by chitosan at either temperature. The addition of chitosan to apple juice delayed spoilage by yeasts but enhanced the survival of E. coli O157:H7. The results suggest that the use of chitosan in the treatment of fruit juices may potentially lead to an increased risk of food poisoning from E. coli O157:H7.
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. Copyright © 2015. Published by Elsevier B.V.
Influence of Zero-Shear on Yeast Development

NASA Technical Reports Server (NTRS)

McGinnis, Michael R.

1997-01-01

The objective of the research was to begin evaluating the effect of zero-shear on the development of the cell wall of Saccharomyces cerevisiae employing the High Aspect Rotating-Wall Vessel (HARV) NASA bioreactor. This particular yeast has enormous potential for research as a model eukaryotic system on the International Space Station, as well as the production of food stuffs' at the future lunar colony. Because the cell wall is the barrier between the cell and the environment, its form and function as influenced by microgravity is of great importance. Morphologic studies revealed that the circularity and total area of the individual yeast cells were essentially the same in both the control and test HARV's. The growth rates were also essentially the same. In zero-shear, the yeast grew in clumps consisting of rudimentary pseudohyphae in contrast to solitary budding cells in the control. Based upon mechanical and sonic shear applied to the yeast cells, those grown in zero-shear had stronger cell walls and septa. This suggests that there are structural differences, most likely related to the chitin skeleton of the cell wall. From this research further NASA support was obtained to continue the work. Investigations will deal with gene expression and ultrastructure. These will lead to a clearer assessment of the value of S. cerevisiae eukaryotic as a model for space station research.
Transport of pyruvate and lactate in yeast mitochondria.

PubMed

Briquet, M

1977-02-07

Evidence for the existence of mediated transport of pyruvate and lactate in isolated mitochondria of Saccharomyces cerevisiae is presented. 1. The mitochondrial oxidation of pyruvate is specifically inhibited by the monocarboxylic oxoacids alpha-ketoisocaproate and by alpha-cyano-3-hydroxycinnamate, while pyruvate and malate dehydrogenases activities are not inhibited. 2. The stimulation of the mitochondrial oxidations of succinate, alpha-ketoglutarate and citrate by pyruvate are also inhibited by alpha-cyano-3-hydroxycinnamate. 3. The [14C]pyruvate uptake by yeast mitochondria follows saturation kinetics and is completely inhibited by alpha-cyano-3-hydroxycinnamate. 4. Large amplitude passive swellings of mitochondria of the wild type and of cytoplasmic rho- and rho-n mutants are induced by isoosmotic ammonium pyruvate and lactate. These pH-dependent swellings are inhibited by alpha-cyano-3-hydroxycinnamate suggesting that the carrier system is not coded by mitochondrial DNA.
The yeast actin cytoskeleton.

PubMed

Mishra, Mithilesh; Huang, Junqi; Balasubramanian, Mohan K

2014-03-01

The actin cytoskeleton is a complex network of dynamic polymers, which plays an important role in various fundamental cellular processes, including maintenance of cell shape, polarity, cell division, cell migration, endocytosis, vesicular trafficking, and mechanosensation. Precise spatiotemporal assembly and disassembly of actin structures is regulated by the coordinated activity of about 100 highly conserved accessory proteins, which nucleate, elongate, cross-link, and sever actin filaments. Both in vivo studies in a wide range of organisms from yeast to metazoans and in vitro studies of purified proteins have helped shape the current understanding of actin dynamics and function. Molecular genetics, genome-wide functional analysis, sophisticated real-time imaging, and ultrastructural studies in concert with biochemical analysis have made yeast an attractive model to understand the actin cytoskeleton, its molecular dynamics, and physiological function. Studies of the yeast actin cytoskeleton have contributed substantially in defining the universal mechanism regulating actin assembly and disassembly in eukaryotes. Here, we review some of the important insights generated by the study of actin cytoskeleton in two important yeast models the budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.
The Est3 protein associates with yeast telomerase through an OB-fold domain

PubMed Central

Lee, Jaesung S.; Mandell, Edward K.; Tucey, Timothy M.; Morris, Danna K.; Victoria, Lundblad

2009-01-01

The Est3 protein is a small regulatory subunit of yeast telomerase which is dispensable for enzyme catalysis but essential for telomere replication in vivo. Using structure prediction combined with in vivo characterization, we show here that Est3 consists of a predicted OB (oligo-saccharide/oligo-nucleotide binding) fold. Mutagenesis of predicted surface residues was used to generate a functional map of one surface of Est3, which identified a site that mediates association with the telomerase complex. Surprisingly, the predicted OB-fold of Est3 is structurally similar to the OB-fold of the mammalian TPP1 protein, despite the fact that Est3 and TPP1, as components of telomerase and a telomere capping complex, respectively, perform functionally distinct tasks at chromosome ends. The analysis performed on Est3 may be instructive in generating comparable missense mutations on the surface of the OB-fold domain of TPP1. PMID:19172754
[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.
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
Combined zebrafish-yeast chemical-genetic screens reveal gene-copper-nutrition interactions that modulate melanocyte pigmentation.

PubMed

Ishizaki, Hironori; Spitzer, Michaela; Wildenhain, Jan; Anastasaki, Corina; Zeng, Zhiqiang; Dolma, Sonam; Shaw, Michael; Madsen, Erik; Gitlin, Jonathan; Marais, Richard; Tyers, Mike; Patton, E Elizabeth

2010-01-01

Hypopigmentation is a feature of copper deficiency in humans, as caused by mutation of the copper (Cu(2+)) transporter ATP7A in Menkes disease, or an inability to absorb copper after gastric surgery. However, many causes of copper deficiency are unknown, and genetic polymorphisms might underlie sensitivity to suboptimal environmental copper conditions. Here, we combined phenotypic screens in zebrafish for compounds that affect copper metabolism with yeast chemical-genetic profiles to identify pathways that are sensitive to copper depletion. Yeast chemical-genetic interactions revealed that defects in intracellular trafficking pathways cause sensitivity to low-copper conditions; partial knockdown of the analogous Ap3s1 and Ap1s1 trafficking components in zebrafish sensitized developing melanocytes to hypopigmentation in low-copper environmental conditions. Because trafficking pathways are essential for copper loading into cuproproteins, our results suggest that hypomorphic alleles of trafficking components might underlie sensitivity to reduced-copper nutrient conditions. In addition, we used zebrafish-yeast screening to identify a novel target pathway in copper metabolism for the small-molecule MEK kinase inhibitor U0126. The zebrafish-yeast screening method combines the power of zebrafish as a disease model with facile genome-scale identification of chemical-genetic interactions in yeast to enable the discovery and dissection of complex multigenic interactions in disease-gene networks.
Visualization and quantification of three-dimensional distribution of yeast in bread dough.

PubMed

Maeda, Tatsuro; DO, Gab-Soo; Sugiyama, Junichi; Araki, Tetsuya; Tsuta, Mizuki; Shiraga, Seizaburo; Ueda, Mitsuyoshi; Yamada, Masaharu; Takeya, Koji; Sagara, Yasuyuki

2009-07-01

A three-dimensional (3-D) bio-imaging technique was developed for visualizing and quantifying the 3-D distribution of yeast in frozen bread dough samples in accordance with the progress of the mixing process of the samples, applying cell-surface engineering to the surfaces of the yeast cells. The fluorescent yeast was recognized as bright spots at the wavelength of 520 nm. Frozen dough samples were sliced at intervals of 1 microm by an micro-slicer image processing system (MSIPS) equipped with a fluorescence microscope for acquiring cross-sectional images of the samples. A set of successive two-dimensional images was reconstructed to analyze the 3-D distribution of the yeast. The average shortest distance between centroids of enhanced green fluorescent protein (EGFP) yeasts was 10.7 microm at the pick-up stage, 9.7 microm at the clean-up stage, 9.0 microm at the final stage, and 10.2 microm at the over-mixing stage. The results indicated that the distribution of the yeast cells was the most uniform in the dough of white bread at the final stage, while the heterogeneous distribution at the over-mixing stage was possibly due to the destruction of the gluten network structure within the samples.
Braving the Waters, or How To Get your Computing "Feet" Wet.

ERIC Educational Resources Information Center

Miller, Pat

1997-01-01

Suggests ways for educators to become computer literate: (1) admit you don't know about computers; (2) be patient with yourself; (3) read about technology; (4) get a home computer; (5) attend training; (6) experiment; (7) ask for assistance; and (8) talk with others about what works for them. (AEF)
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.
Discrete dynamical system modelling for gene regulatory networks of 5-hydroxymethylfurfural tolerance for ethanologenic yeast.

PubMed

Song, M; Ouyang, Z; Liu, Z L

2009-05-01

Composed of linear difference equations, a discrete dynamical system (DDS) model was designed to reconstruct transcriptional regulations in gene regulatory networks (GRNs) for ethanologenic yeast Saccharomyces cerevisiae in response to 5-hydroxymethylfurfural (HMF), a bioethanol conversion inhibitor. The modelling aims at identification of a system of linear difference equations to represent temporal interactions among significantly expressed genes. Power stability is imposed on a system model under the normal condition in the absence of the inhibitor. Non-uniform sampling, typical in a time-course experimental design, is addressed by a log-time domain interpolation. A statistically significant DDS model of the yeast GRN derived from time-course gene expression measurements by exposure to HMF, revealed several verified transcriptional regulation events. These events implicate Yap1 and Pdr3, transcription factors consistently known for their regulatory roles by other studies or postulated by independent sequence motif analysis, suggesting their involvement in yeast tolerance and detoxification of the inhibitor.

Antagonistic interactions between garden yeasts and microfungal garden pathogens of leaf-cutting ants.

PubMed

Rodrigues, Andre; Cable, Rachel N; Mueller, Ulrich G; Bacci, Maurício; Pagnocca, Fernando C

2009-10-01

We investigate the diversity of yeasts isolated in gardens of the leafcutter ant Atta texana. Repeated sampling of gardens from four nests over a 1-year time period showed that gardens contain a diverse assemblage of yeasts. The yeast community in gardens consisted mostly of yeasts associated with plants or soil, but community composition changed between sampling periods. In order to understand the potential disease-suppressing roles of the garden yeasts, we screened isolates for antagonistic effects against known microfungal garden contaminants. In vitro assays revealed that yeasts inhibited the mycelial growth of two strains of Escovopsis (a specialized attine garden parasite), Syncephalastrum racemosum (a fungus often growing in gardens of leafcutter lab nests), and the insect pathogen Beauveria bassiana. These garden yeasts add to the growing list of disease-suppressing microbes in attine nests that may contribute synergistically, together with actinomycetes and Burkholderia bacteria, to protect the gardens and the ants against diseases. Additionally, we suggest that garden immunity against problem fungi may therefore derive not only from the presence of disease-suppressing Pseudonocardia actinomycetes, but from an enrichment of multiple disease-suppressing microorganisms in the garden matrix.
β-(1 → 3)-Glucanolytic yeasts from Brazilian grape microbiota: production and characterization of β-glucanolytic enzymes by Aureobasidium pullulans 1WA1 cultivated on fungal Mycelium.

PubMed

Bauermeister, Anelize; Amador, Ismael R; Pretti, Carla P; Giese, Ellen C; Oliveira, André L M

2015-01-14

A total of 95 yeast strains were isolated from the microbiota of different grapes collected at vineyards in southern Brazil. The yeasts were screened for β-(1 → 3)-glucanases using a newly developed zymogram method that relies upon the appearance of clearance zones around growing colonies cultured on agar–botryosphaeran medium and also by submerged fermentation on nutrient medium containing botryosphaeran, a (1 → 3),(1 → 6)-β-d-glucan. Among 14 β-(1 → 3)-glucanase-positive yeasts identified, four strains produced the highest β-glucanolytic activities and were evaluated for enzyme production on cellobiose, botryosphaeran, and mycelial biomass from Botryosphaeria rhodina (MAMB-05). Yeast strain 1WA1 produced the highest β-(1 → 3)-glucanase and β-glucosidase activities and was identified by molecular characterization as Aureobasidium pullulans. The physicochemical properties of the crude β-glucanolytic enzyme preparation were characterized, and the preparation was used to hydrolyze several β-d-glucans (laminarin, botryosphaeran, lasiodiplodan, pustulan, and curdlan). The production and physicochemical properties of the β-glucanolytic preparation enable its potential applications in wine enology and production of prebiotics through hydrolysis of β-d-glucans.
Chlorhexidine: beta-cyclodextrin inhibits yeast growth by extraction of ergosterol.

PubMed

Teixeira, K I R; Araújo, P V; Sinisterra, R D; Cortés, M E

2012-04-01

Chlorhexidine (Cx) augmented with beta-cyclodextrin (β-cd) inclusion compounds, termed Cx:β-cd complexes, have been developed for use as antiseptic agents. The aim of this study was to examine the interactions of Cx:β-cd complexes, prepared at different molecular ratios, with sterol and yeast membranes. The Minimal Inhibitory Concentration (MIC) against the yeast Candida albicans (C.a.) was determined for each complex; the MICs were found to range from 0.5 to 2 μg/mL. To confirm the MIC data, quantitative analysis of viable cells was performed using trypan blue staining. Mechanistic characterization of the interactions that the Cx:β-cd complexes have with the yeast membrane and assessment of membrane morphology following exposure to Cx:β-cd complexes were performed using Sterol Quantification Method analysis (SQM) and scanning electron microscopy (SEM). SQM revealed that sterol extraction increased with increasing β-cd concentrations (1.71 ×10(3); 1.4 ×10(3); 3.45 ×10(3), and 3.74 ×10(3) CFU for 1:1, 1:2, 1:3, and 1:4, respectively), likely as a consequence of membrane ergosterol solubilization. SEM images demonstrated that cell membrane damage is a visible and significant mechanism that contributes to the antimicrobial effects of Cx:β-cd complexes. Cell disorganization increased significantly as the proportion of β-cyclodextrin present in the complex increased. Morphology of cells exposed to complexes with 1:3 and 1:4 molar ratios of Cx:β-cd were observed to have large aggregates mixed with yeast remains, representing more membrane disruption than that observed in cells treated with Cx alone. In conclusion, nanoaggregates of Cx:β-cd complexes block yeast growth via ergosterol extraction, permeabilizing the membrane by creating cluster-like structures within the cell membrane, possibly due to high amounts of hydrogen bonding.
UCS Protein Rng3p Is Essential for Myosin-II Motor Activity during Cytokinesis in Fission Yeast

PubMed Central

Stark, Benjamin C.; James, Michael L.; Pollard, Luther W.; Sirotkin, Vladimir; Lord, Matthew

2013-01-01

UCS proteins have been proposed to operate as co-chaperones that work with Hsp90 in the de novo folding of myosin motors. The fission yeast UCS protein Rng3p is essential for actomyosin ring assembly and cytokinesis. Here we investigated the role of Rng3p in fission yeast myosin-II (Myo2p) motor activity. Myo2p isolated from an arrested rng3-65 mutant was capable of binding actin, yet lacked stability and activity based on its expression levels and inactivity in ATPase and actin filament gliding assays. Myo2p isolated from a myo2-E1 mutant (a mutant hyper-sensitive to perturbation of Rng3p function) showed similar behavior in the same assays and exhibited an altered motor conformation based on limited proteolysis experiments. We propose that Rng3p is not required for the folding of motors per se, but instead works to ensure the activity of intrinsically unstable myosin-II motors. Rng3p is specific to conventional myosin-II and the actomyosin ring, and is not required for unconventional myosin motor function at other actin structures. However, artificial destabilization of myosin-I motors at endocytic actin patches (using a myo1-E1 mutant) led to recruitment of Rng3p to patches. Thus, while Rng3p is specific to myosin-II, UCS proteins are adaptable and can respond to changes in the stability of other myosin motors. PMID:24244528
Kinetic Analysis of a Molecular Model of the Budding Yeast Cell Cycle

PubMed Central

Chen, Katherine C.; Csikasz-Nagy, Attila; Gyorffy, Bela; Val, John; Novak, Bela; Tyson, John J.

2000-01-01

The molecular machinery of cell cycle control is known in more detail for budding yeast, Saccharomyces cerevisiae, than for any other eukaryotic organism. In recent years, many elegant experiments on budding yeast have dissected the roles of cyclin molecules (Cln1–3 and Clb1–6) in coordinating the events of DNA synthesis, bud emergence, spindle formation, nuclear division, and cell separation. These experimental clues suggest a mechanism for the principal molecular interactions controlling cyclin synthesis and degradation. Using standard techniques of biochemical kinetics, we convert the mechanism into a set of differential equations, which describe the time courses of three major classes of cyclin-dependent kinase activities. Model in hand, we examine the molecular events controlling “Start” (the commitment step to a new round of chromosome replication, bud formation, and mitosis) and “Finish” (the transition from metaphase to anaphase, when sister chromatids are pulled apart and the bud separates from the mother cell) in wild-type cells and 50 mutants. The model accounts for many details of the physiology, biochemistry, and genetics of cell cycle control in budding yeast. PMID:10637314
Polyhexamethyl biguanide can eliminate contaminant yeasts from fuel-ethanol fermentation process.

PubMed

Elsztein, Carolina; de Menezes, João Assis Scavuzzi; de Morais, Marcos Antonio

2008-09-01

Industrial ethanol fermentation is a non-sterile process and contaminant microorganisms can lead to a decrease in industrial productivity and significant economic loss. Nowadays, some distilleries in Northeastern Brazil deal with bacterial contamination by decreasing must pH and adding bactericides. Alternatively, contamination can be challenged by adding a pure batch of Saccharomyces cerevisiae-a time-consuming and costly process. A better strategy might involve the development of a fungicide that kills contaminant yeasts while preserving S. cerevisiae cells. Here, we show that polyhexamethyl biguanide (PHMB) inhibits and kills the most important contaminant yeasts detected in the distilleries of Northeastern Brazil without affecting the cell viability and fermentation capacity of S. cerevisiae. Moreover, some physiological data suggest that PHMB acts through interaction with the yeast membrane. These results support the development of a new strategy for controlling contaminant yeast population whilst keeping industrial yields high.
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
Phenotypic and metabolic traits of commercial Saccharomyces cerevisiae yeasts.

PubMed

Barbosa, Catarina; Lage, Patrícia; Vilela, Alice; Mendes-Faia, Arlete; Mendes-Ferreira, Ana

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.
High-Gravity Brewing: Effects of Nutrition on Yeast Composition, Fermentative Ability, and Alcohol Production

PubMed Central

Casey, Gregory P.; Magnus, Carol A.; Ingledew, W. M.

1984-01-01

A number of economic and product quality advantages exist in brewing when high-gravity worts of 16 to 18% dissolved solids are fermented. Above this level, production problems such as slow or stuck fermentations and poor yeast viability occur. Ethanol toxicity has been cited as the main cause, as brewers' yeasts are reported to tolerate only 7 to 9% (vol/vol) ethanol. The inhibitory effect of high osmotic pressure has also been implicated. In this report, it is demonstrated that the factor limiting the production of high levels of ethanol by brewing yeasts is actually a nutritional deficiency. When a nitrogen source, ergosterol, and oleic acid are added to worts up to 31% dissolved solids, it is possible to produce beers up to 16.2% (vol/vol) ethanol. Yeast viability remains high, and the yeasts can be repitched at least five times. Supplementation does not increase the fermentative tolerance of the yeasts to ethanol but increases the length and level of new yeast cell mass synthesis over that seen in unsupplemented wort (and therefore the period of more rapid wort attenuation). Glycogen, protein, and sterol levels in yeasts were examined, as was the importance of pitching rate, temperature, and degree of anaerobiosis. The ethanol tolerance of brewers' yeast is suggested to be no different than that of sake or distillers' yeast. PMID:16346630
Assessment of Accuracy of Identification of Pathogenic Yeasts in Microbiology Laboratories in the United Kingdom

PubMed Central

Szekely, Adrien; Palmer, Michael D.; Johnson, Elizabeth M.

2012-01-01

Rapid, accurate identification of yeast isolates from clinical samples has always been important given their innately variable antifungal susceptibility profiles. Recently, this has become paramount with the proposed introduction of species-specific interpretive breakpoints for MICs obtained in yeast antifungal susceptibility tests (M. A. Pfaller, D. Andes, D. J. Diekema, A. Espinel–Ingroff, D. Sheehan, and CLSI Subcommittee for Antifungal Susceptibility Testing, Drug Resist. Updat. 13:180–195, 2010). Here, we present the results of a 12-month evaluation of the accuracy of identifications that accompany yeast isolates submitted to the Mycology Reference Laboratory (United Kingdom) for either confirmation of identity or susceptibility testing. In total, 1,781 yeast isolates were analyzed, and the robustness of prior identifications obtained in microbiology laboratories throughout the United Kingdom was assessed using a combination of culture on chromogenic agar, morphology on cornmeal agar, and molecular identification by pyrosequencing. Over 40% of isolates (755) were submitted without any suggested identification. Of those isolates with a prior identification, 100 (9.7%) were incorrectly identified. Error rates ranged from 5.2% (for organisms submitted for antifungal susceptibility testing) to 18.2% (for organisms requiring confirmation of identity) and varied in a strictly species-specific manner. At least 50% of identification errors would be likely to affect interpretation of MIC data, with a possible impact on patient management. In addition, 2.3% of submitted cultures were found to contain mixtures of at least two yeast species. The vast majority of mixtures had gone undetected in the referring laboratory and would have impacted the interpretation of antifungal susceptibility profiles and patient management. Some of the more common misidentifications are discussed according to the identification method employed, with suggestions for avoiding such
Assessment of accuracy of identification of pathogenic yeasts in microbiology laboratories in the United kingdom.

PubMed

Borman, Andrew M; Szekely, Adrien; Palmer, Michael D; Johnson, Elizabeth M

2012-08-01

Rapid, accurate identification of yeast isolates from clinical samples has always been important given their innately variable antifungal susceptibility profiles. Recently, this has become paramount with the proposed introduction of species-specific interpretive breakpoints for MICs obtained in yeast antifungal susceptibility tests (M. A. Pfaller, D. Andes, D. J. Diekema, A. Espinel-Ingroff, D. Sheehan, and CLSI Subcommittee for Antifungal Susceptibility Testing, Drug Resist. Updat. 13:180-195, 2010). Here, we present the results of a 12-month evaluation of the accuracy of identifications that accompany yeast isolates submitted to the Mycology Reference Laboratory (United Kingdom) for either confirmation of identity or susceptibility testing. In total, 1,781 yeast isolates were analyzed, and the robustness of prior identifications obtained in microbiology laboratories throughout the United Kingdom was assessed using a combination of culture on chromogenic agar, morphology on cornmeal agar, and molecular identification by pyrosequencing. Over 40% of isolates (755) were submitted without any suggested identification. Of those isolates with a prior identification, 100 (9.7%) were incorrectly identified. Error rates ranged from 5.2% (for organisms submitted for antifungal susceptibility testing) to 18.2% (for organisms requiring confirmation of identity) and varied in a strictly species-specific manner. At least 50% of identification errors would be likely to affect interpretation of MIC data, with a possible impact on patient management. In addition, 2.3% of submitted cultures were found to contain mixtures of at least two yeast species. The vast majority of mixtures had gone undetected in the referring laboratory and would have impacted the interpretation of antifungal susceptibility profiles and patient management. Some of the more common misidentifications are discussed according to the identification method employed, with suggestions for avoiding such
Yeast flocculation: New story in fuel ethanol production.

PubMed

Zhao, X Q; Bai, F W

2009-01-01

Yeast flocculation has been used in the brewing industry to facilitate biomass recovery for a long time, and thus its mechanism of yeast flocculation has been intensively studied. However, the application of flocculating yeast in ethanol production garnered attention mainly in the 1980s and 1990s. In this article, updated research progress in the molecular mechanism of yeast flocculation and the impact of environmental conditions on yeast flocculation are reviewed. Construction of flocculating yeast strains by genetic approach and utilization of yeast flocculation for ethanol production from various feedstocks were presented. The concept of self-immobilized yeast cells through their flocculation is revisited through a case study of continuous ethanol fermentation with the flocculating yeast SPSC01, and their technical and economic advantages are highlighted by comparing with yeast cells immobilized with supporting materials and regular free yeast cells as well. Taking the flocculating yeast SPSC01 as an example, the ethanol tolerance of the flocculating yeast was also discussed.
RNA interactome capture in yeast.

PubMed

Beckmann, Benedikt M

2017-04-15

RNA-binding proteins (RBPs) are key players in post-transcriptional regulation of gene expression in eukaryotic cells. To be able to unbiasedly identify RBPs in Saccharomyces cerevisiae, we developed a yeast RNA interactome capture protocol which employs RNA labeling, covalent UV crosslinking of RNA and proteins at 365nm wavelength (photoactivatable-ribonucleoside-enhanced crosslinking, PAR-CL) and finally purification of the protein-bound mRNA. The method can be easily implemented in common workflows and takes about 3days to complete. Next to a comprehensive explanation of the method, we focus on our findings about the choice of crosslinking in yeast and discuss the rationale of individual steps in the protocol. Copyright © 2016. Published by Elsevier Inc.
The PGM3 gene encodes the major phosphoribomutase in the yeast Saccharomyces cerevisiae.

PubMed

Walther, Thomas; Baylac, Audrey; Alkim, Ceren; Vax, Amélie; Cordier, Hélène; François, Jean Marie

2012-11-30

The phosphoglucomutases (PGM) Pgm1, Pgm2, and Pgm3 of the yeast Saccharomyces cerevisiae were tested for their ability to interconvert ribose-1-phosphate and ribose-5-phosphate. The purified proteins were studied in vitro with regard to their kinetic properties on glucose-1-phosphate and ribose-1-phosphate. All tested enzymes were active on both substrates with Pgm1 exhibiting only residual activity on ribose-1-phosphate. The Pgm2 and Pgm3 proteins had almost equal kinetic properties on ribose-1-phosphate, but Pgm2 had a 2000 times higher preference for glucose-1-phosphate when compared to Pgm3. The in vivo function of the PGMs was characterized by monitoring ribose-1-phosphate kinetics following a perturbation of the purine nucleotide balance. Only mutants with a deletion of PGM3 hyper-accumulated ribose-1-phosphate. We conclude that Pgm3 functions as the major phosphoribomutase in vivo. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
Get Enough Calcium

MedlinePlus

... Vitamins 3 of 4 sections Take Action: Vitamin D Get enough vitamin D. Vitamin D helps your body absorb (take in) calcium. Find out how much vitamin D you need each day . Your body makes vitamin ...
Assessment of yeast Saccharomyces cerevisiae component binding to Mycobacterium avium subspecies paratuberculosis using bovine epithelial cells.

PubMed

Li, Ziwei; You, Qiumei; Ossa, Faisury; Mead, Philip; Quinton, Margaret; Karrow, Niel A

2016-03-01

Since yeast Saccharomyces cerevisiae and its components are being used for the prevention and treatment of enteric diseases in different species, they may also be useful for preventing Johne's disease, a chronic inflammatory bowel disease of ruminants caused by Mycobacterium avium spp. paratuberculosis (MAP). This study aimed to identify potential yeast derivatives that may be used to help prevent MAP infection. The adherence of mCherry-labeled MAP to bovine mammary epithelial cell line (MAC-T cells) and bovine primary epithelial cells (BECs) co-cultured with yeast cell wall components (CWCs) from four different yeast strains (A, B, C and D) and two forms of dead yeast from strain A was investigated. The CWCs from all four yeast strains and the other two forms of dead yeast from strain A reduced MAP adhesion to MAC-T cells and BECs in a concentration-dependent manner after 6-h of exposure, with the dead yeast having the greatest effect. The following in vitro binding studies suggest that dead yeast and its' CWCs may be useful for reducing risk of MAP infection.
Assessment of Multi Fragment Melting Analysis System (MFMAS) for the Identification of Food-Borne Yeasts.

PubMed

Kesmen, Zülal; Büyükkiraz, Mine E; Özbekar, Esra; Çelik, Mete; Özkök, F Özge; Kılıç, Özge; Çetin, Bülent; Yetim, Hasan

2018-06-01

Multi Fragment Melting Analysis System (MFMAS) is a novel approach that was developed for the species-level identification of microorganisms. It is a software-assisted system that performs concurrent melting analysis of 8 different DNA fragments to obtain a fingerprint of each strain analyzed. The identification is performed according to the comparison of these fingerprints with the fingerprints of known yeast species recorded in a database to obtain the best possible match. In this study, applicability of the yeast version of the MFMAS (MFMAS-yeast) was evaluated for the identification of food-associated yeast species. For this purpose, in this study, a total of 145 yeast strains originated from foods and beverages and 19 standard yeast strains were tested. The DNAs isolated from these yeast strains were analyzed by the MFMAS, and their species were successfully identified with a similarity rate of 95% or higher. It was shown that the strains belonged to 43 different yeast species that are widely found in the foods. A clear discrimination was also observed in the phylogenetically related species. In conclusion, it might be suggested that the MFMAS-yeast seems to be a highly promising approach for a rapid, accurate, and one-step identification of the yeasts isolated from food products and/or their processing environments.
A polyphasic study on the taxonomic position of industrial sour dough yeasts.

PubMed

Mäntynen, V H; Korhola, M; Gudmundsson, H; Turakainen, H; Alfredsson, G A; Salovaara, H; Lindström, K

1999-02-01

The sour dough bread making process is extensively used to produce wholesome palatable rye bread. The process is traditionally done using a back-slopping procedure. Traditional sour doughs in Finland comprise of lactic acid bacteria and yeasts. The yeasts present in these doughs have been enriched in the doughs due to their metabolic activities, e.g. acid tolerance. We characterized the yeasts in five major sour bread bakeries in Finland. We found that most of the commercial sour doughs contained yeasts which were similar to Candida milleri on the basis of 18S rDNA and EF-3 PCR-RFLP patterns and metabolic activities. Some of the bakery yeasts exhibited extensive karyotype polymorphism. The minimum growth temperature was 8 degrees C for C. milleri and also for most of sour dough yeasts.
Strategies for identifying new prions in yeast

PubMed Central

MacLea, Kyle S

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. PMID:22052351
Preparation of corncob grits as a carrier for immobilizing yeast cells for ethanol production.

PubMed

Lee, Sang-Eun; Lee, Choon Geun; Kang, Do Hyung; Lee, Hyeon-Yong; Jung, Kyung-Hwan

2012-12-01

In this study, DEAE-corncobs [delignified corncob grits derivatized with 2-(diethylamino)ethyl chloride hydrochloride (DEAE·HCl)] were prepared as a carrier to immobilize yeast (Saccharomyces cerevisiae) for ethanol production. The immobilized yeast cell reactor produced ethanol under optimized DEAE·HCl derivatization and adsorption conditions between yeast cells and the DEAE-corncobs. When delignified corncob grit (3.0 g) was derivatized with 0.5M DEAE·HCl, the yeast cell suspension (OD600 = 3.0) was adsorbed at >90% of the initial cell OD600. This amount of adsorbed yeast cells was estimated to be 5.36 mg-dry cells/g-DEAE corncobs. The Qmax (the maximum cell adsorption by the carrier) of the DEAE-corncobs was estimated to be 25.1 (mg/g), based on a Languir model biosorption isotherm experiment. When we conducted a batch culture with medium recycling using the immobilized yeast cells, the yeast cells on DEAE-corncobs produced ethanol gradually, according to glucose consumption, without cells detaching from the DEAE-corncobs. We observed under electron microscopy that the yeast cells grew on the surface and in the holes of the DEAEcorncobs. In a future study, DEAE-corncobs and the immobilized yeast cell reactor system will contribute to bioethanol production from biomass hydrolysates.

Reconstitution of plant alkane biosynthesis in yeast demonstrates that Arabidopsis ECERIFERUM1 and ECERIFERUM3 are core components of a very-long-chain alkane synthesis complex.

PubMed

Bernard, Amélie; Domergue, Frédéric; Pascal, Stéphanie; Jetter, Reinhard; Renne, Charlotte; Faure, Jean-Denis; Haslam, Richard P; Napier, Johnathan A; Lessire, René; Joubès, Jérôme

2012-07-01

In land plants, very-long-chain (VLC) alkanes are major components of cuticular waxes that cover aerial organs, mainly acting as a waterproof barrier to prevent nonstomatal water loss. Although thoroughly investigated, plant alkane synthesis remains largely undiscovered. The Arabidopsis thaliana ECERIFERUM1 (CER1) protein has been recognized as an essential element of wax alkane synthesis; nevertheless, its function remains elusive. In this study, a screen for CER1 physical interaction partners was performed. The screen revealed that CER1 interacts with the wax-associated protein ECERIFERUM3 (CER3) and endoplasmic reticulum-localized cytochrome b5 isoforms (CYTB5s). The functional relevance of these interactions was assayed through an iterative approach using yeast as a heterologous expression system. In a yeast strain manipulated to produce VLC acyl-CoAs, a strict CER1 and CER3 coexpression resulted in VLC alkane synthesis. The additional presence of CYTB5s was found to enhance CER1/CER3 alkane production. Site-directed mutagenesis showed that CER1 His clusters are essential for alkane synthesis, whereas those of CER3 are not, suggesting that CYTB5s are specific CER1 cofactors. Collectively, our study reports the identification of plant alkane synthesis enzymatic components and supports a new model for alkane production in which CER1 interacts with both CER3 and CYTB5 to catalyze the redox-dependent synthesis of VLC alkanes from VLC acyl-CoAs.
Opportunistic Pathogenic Yeasts

NASA Astrophysics Data System (ADS)

Banerjee, Uma

Advances in medical research, made during the last few decades, have improved the prophylactic, diagnostic and therapeutic capabilities for variety of infections/diseases. However, many of the prophylactic and therapeutic procedures have been seen in many instances to exact a price of host-vulnerability to an expanding group of opportunistic pathogens and yeasts are one of the important members in it. Fortunately amongst the vast majority of yeasts present in nature only few are considered to have the capability to cause infections when certain opportunities predisposes and these are termed as ‘opportunistic pathogenic yeasts.’ However, the term ‘pathogenic’ is quite tricky, as it depends of various factors of the host, the ‘bug’ and the environment to manifest the clinical infection. The borderline is expanding. In the present century with unprecedented increase in number of immune-compromised host in various disciplines of health care settings, where any yeast, which has the capability to grow at 37 ° C (normal body temperature of human), can be pathogenic and cause infection in particular situation
Vegemite Beer: yeast extract spreads as nutrient supplements to promote fermentation.

PubMed

Kerr, Edward D; Schulz, Benjamin L

2016-01-01

Vegemite is an iconic Australian food spread made from spent brewers' yeast extract, which has been reported to be used as an ingredient in illegal home brewing. In this study, we tested the utility of Vegemite and the similar spread Marmite in promoting fermentation. We could not culture microorganisms from either Vegemite or Marmite, consistent with these food-grade spreads being essentially sterile. To test if the addition of Vegemite or Marmite could assist in fermentation when additional viable yeast was also present, solutions containing glucose and a range of concentrations of either Vegemite or Marmite were inoculated with brewers' yeast. No fermentation occurred in any condition without addition of extra brewer's yeast. Fermentation did not occur when yeast was inoculated into solutions containing only glucose, but progressed efficiently with when Vegemite or Marmite was also added. Gas Chromatography confirmed that ethanol was present at ∼3% v/v post-fermentation in all samples which contained glucose, Vegemite or Marmite, and brewers' yeast. Trace amounts of methanol were also detected. Mass spectrometry proteomics identified abundant intracellular yeast proteins and barley proteins in Vegemite and Marmite, and abundant secreted yeast proteins from actively growing yeast in those samples to which extra brewers' yeast had been added. We estimate that the real-world cost of home brewed "Vegemite Beer" would be very low. Our results show that Vegemite or other yeast extract spreads could provide cheap and readily available sources of nutrient supplementation to increase the efficiency of fermentation in home brewing or other settings.
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
The contribution of glutathione to the destabilizing effect of yeast on wheat dough.

PubMed

Verheyen, C; Albrecht, A; Herrmann, J; Strobl, M; Jekle, M; Becker, T

2015-04-15

Any factor which impairs the development of the gluten network affects the gas retention capacity and the overall baking performance. This study aimed to examine why rising yeast concentrations (Saccharomyces cerevisiae) decrease the dough elasticity in an asymptotic manner. Since in 27 commercial fresh and dry yeasts up to 81 mg glutathione (GSH) per 1g dry sample were found. Through the addition of reduced GSH in dough without yeast, the extent of dough weakening was analysed. Indeed rheological measurements confirmed that yeast-equivalent levels of GSH had a softening effect and during 3h fermentation the weakening coefficient increased from 0.3% to 20.4% in a Rheofermentometer. The present results indicate that free -SH compounds, as represented by GSH, considerably contribute to the softening of dough through dead yeast cells. Copyright © 2014 Elsevier Ltd. All rights reserved.
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.
Evaluation of pectinolytic activities for oenological uses from psychrotrophic yeasts.

PubMed

Sahay, S; Hamid, B; Singh, P; Ranjan, K; Chauhan, D; Rana, R S; Chaurse, V K

2013-08-01

Of the twenty-three morphotypes of yeasts isolated from soil capable of utilizing pectin as sole carbon source at 6°C, two yeast isolates, one psychrotolerant (PT1) and one psychrophilic (SPY11), were selected according to their ability to secrete pectinolytic enzymes under some oenological conditions (temperature 6 and 12°C and pH 3.5) and ability or inability to grow above 20°C, respectively. As compared to their optimal activity, the three pectinolytic enzymes viz., pectin methyl esterase (PME), endopolygalacturonase (endo-PG) and exopolygalacturonase (exo-PG) isolated and assayed at pH 3.5 from PT1 were found to retain 39, 60 and 60% activity at 12°C and 40, 79 and 74% activity at 28°C, respectively. Likewise, the enzymes PME and endo-PG at pH 3.5 from SPY11 displayed 46 and 86% activity at 12°C and 50 and 60% activity at 28°C, respectively. All these enzymes showed 20-90% of residual activity at pH 3.5 and 6°C. The yeast isolates PT1 and SPY11 were identified as Rhodotorula mucilaginosa and Cystofilobasidium capitatum, respectively, on the basis of morphological, physiological and molecular characteristics. This study presents the first report on pectinolytic activities under major oenological conditions from psychrotolerant isolate R. mucilaginosa PT1 and psychrophilic isolate C. capitatum SPY11. The cold-active pectinolytic enzymes (PME, endo-PG and exo-PG) from the newly isolated and identified psychrophilic yeast Cystofilobasidium capitatum SPY11 and psychrotolerant yeast Rhodotorula mucilaginosa PT1that exhibited 50-80% of their optimum activity under some major oenological conditions pH (3.5) and temperatures (6 and 12°C) could be applied to wine production and juice clarification at low temperature. The psychrotrophic yeasts themselves could be applied to cold process for the production of enzymes thus saving cost of energy and protecting process from contamination. © 2013 The Society for Applied Microbiology.
Yeast Droplets

NASA Astrophysics Data System (ADS)

Nguyen, Baochi; Upadhyaya, Arpita; van Oudenaarden, Alexander; Brenner, Michael

2002-11-01

It is well known that the Young's law and surface tension govern the shape of liquid droplets on solid surfaces. Here we address through experiments and theory the shape of growing aggregates of yeast on agar substrates, and assess whether these ideas still hold. Experiments are carried out on Baker's yeast, with different levels of expressions of an adhesive protein governing cell-cell and cell-substrate adhesion. Changing either the agar concentration or the expression of this protein modifies the local contact angle of a yeast droplet. When the colony is small, the shape is a spherical cap with the contact angle obeying Young's law. However, above a critical volume this structure is unstable, and the droplet becomes nonspherical. We present a theoretical model where this instability is caused by bulk elastic effects. The model predicts that the transition depends on both volume and contact angle, in a manner quantitatively consistent with our experiments.
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. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.
Functional Coupling of a Nematode Chemoreceptor to the Yeast Pheromone Response Pathway

PubMed Central

Tehseen, Muhammad; Dumancic, Mira; Briggs, Lyndall; Wang, Jian; Berna, Amalia; Anderson, Alisha; Trowell, Stephen

2014-01-01

Sequencing of the Caenorhabditis elegans genome revealed sequences encoding more than 1,000 G-protein coupled receptors, hundreds of which may respond to volatile organic ligands. To understand how the worm's simple olfactory system can sense its chemical environment there is a need to characterise a representative selection of these receptors but only very few receptors have been linked to a specific volatile ligand. We therefore set out to design a yeast expression system for assigning ligands to nematode chemoreceptors. We showed that while a model receptor ODR-10 binds to C. elegans Gα subunits ODR-3 and GPA-3 it cannot bind to yeast Gα. However, chimaeras between the nematode and yeast Gα subunits bound to both ODR-10 and the yeast Gβγ subunits. FIG2 was shown to be a superior MAP-dependent promoter for reporter expression. We replaced the endogenous Gα subunit (GPA1) of the Saccharomyces cerevisiae (ste2Δ sst2Δ far1Δ) triple mutant (“Cyb”) with a Gpa1/ODR-3 chimaera and introduced ODR-10 as a model nematode GPCR. This strain showed concentration-dependent activation of the yeast MAP kinase pathway in the presence of diacetyl, the first time that the native form of a nematode chemoreceptor has been functionally expressed in yeast. This is an important step towards en masse de-orphaning of C. elegans chemoreceptors. PMID:25415379
The implementation of high fermentative 2,3-butanediol production from xylose by simultaneous additions of yeast extract, Na2EDTA, and acetic acid.

PubMed

Wang, Xiao-Xiong; Hu, Hong-Ying; Liu, De-Hua; Song, Yuan-Quan

2016-01-25

The effective use of xylose may significantly enhance the feasibility of using lignocellulosic hydrolysate to produce 2,3-butanediol (2,3-BD). Previous difficulties in 2,3-BD production include that the high-concentration xylose cannot be converted completely and the fermentation rate is slow. This study investigated the effects of yeast extract, ethylenediaminetetraacetic acid disodium salt (Na2EDTA), and acetic acid on 2,3-BD production from xylose. The central composite design approach was used to optimize the concentrations of these components. It was found that simultaneous addition of yeast extract, Na2EDTA, and acetic acid could significantly improve 2,3-BD production. The optimal concentrations of yeast extract, Na2EDTA, and acetic acid were 35.2, 1.2, and 4.5 g/L, respectively. The 2,3-BD concentration in the optimized medium reached 39.7 g/L after 48 hours of shake flask fermentation, the highest value ever reported in such a short period. The xylose utilization ratio and the 2,3-BD concentration increased to 99.0% and 42.7 g/L, respectively, after 48 hours of stirred batch fermentation. Furthermore, the 2,3-BD yield was 0.475 g/g, 95.0% of the theoretical maximum value. As the major components of lignocellulosic hydrolysate are glucose, xylose, and acetic acid, the results of this study indicate the possibility of directly using the hydrolysate to effectively produce 2,3-BD. Copyright © 2015 Elsevier B.V. All rights reserved.
mlh3 mutations in baker’s yeast alter meiotic recombination outcomes by increasing noncrossover events genome-wide

PubMed Central

Al-Sweel, Najla; Raghavan, Vandana; Khondakar, Nabila; Manhart, Carol M.; Surtees, Jennifer A.

2017-01-01

Mlh1-Mlh3 is an endonuclease hypothesized to act in meiosis to resolve double Holliday junctions into crossovers. It also plays a minor role in eukaryotic DNA mismatch repair (MMR). To understand how Mlh1-Mlh3 functions in both meiosis and MMR, we analyzed in baker’s yeast 60 new mlh3 alleles. Five alleles specifically disrupted MMR, whereas one (mlh3-32) specifically disrupted meiotic crossing over. Mlh1-mlh3 representatives for each class were purified and characterized. Both Mlh1-mlh3-32 (MMR+, crossover-) and Mlh1-mlh3-45 (MMR-, crossover+) displayed wild-type endonuclease activities in vitro. Msh2-Msh3, an MSH complex that acts with Mlh1-Mlh3 in MMR, stimulated the endonuclease activity of Mlh1-mlh3-32 but not Mlh1-mlh3-45, suggesting that Mlh1-mlh3-45 is defective in MSH interactions. Whole genome recombination maps were constructed for wild-type and MMR+ crossover-, MMR- crossover+, endonuclease defective and null mlh3 mutants in an S288c/YJM789 hybrid background. Compared to wild-type, all of the mlh3 mutants showed increases in the number of noncrossover events, consistent with recombination intermediates being resolved through alternative recombination pathways. Our observations provide a structure-function map for Mlh3 that reveals the importance of protein-protein interactions in regulating Mlh1-Mlh3’s enzymatic activity. They also illustrate how defective meiotic components can alter the fate of meiotic recombination intermediates, providing new insights for how meiotic recombination pathways are regulated. PMID:28827832
A Steroidal Saponin from Ophiopogon japonicus Extends the Lifespan of Yeast via the Pathway Involved in SOD and UTH1

PubMed Central

Sun, Kaiyue; Cao, Shining; Pei, Liang; Matsuura, Akira; Xiang, Lan; Qi, Jianhua

2013-01-01

Nolinospiroside F is a steroidal saponin isolated from Ophiopogon japonicus (O. japonicus). In this study, we found that nolinospiroside F significantly extends the replicative lifespan of K6001 yeast at doses of 1, 3 and 10 μM, indicating that it has an anti-aging effect. This may be attributed to its anti-oxidative effect, as nolinospiroside F could increase yeast survival under oxidative stress conditions and decrease the level of malondialdehyde (MDA), an oxidative stress biomarker. It could also increase anti-oxidative stress genes, SOD1 and SOD2, expression, and the activity of superoxide dismutase (SOD). It increase the activity of SIRT1, an upstream inducer of SOD2 expression. In sod1 and sod2 mutant yeast strains, nolinospiroside F failed to extend their replicative lifespan. These results indicate that SOD participates in the anti-aging effect of nolinospiroside F. Furthermore, nolinospiroside F inhibited the expression of UTH1, a yeast-aging gene that is involved in the oxidative stress of yeast, and failed to extend the replicative lifespan of uth1 or skn7 mutant yeast cells. SKN7 is the transcriptional activator of UTH1. We also demonstrate that SOD and UTH1 regulate each other’s expression. Together, these results suggest that SOD and UTH1 genes are required for and play interactive roles in nolinospiroside F-mediated yeast lifespan extension. PMID:23439553
Development of intra-strain self-cloning procedure for breeding baker's yeast strains.

PubMed

Nakagawa, Youji; Ogihara, Hiroyuki; Mochizuki, Chisato; Yamamura, Hideki; Iimura, Yuzuru; Hayakawa, Masayuki

2017-03-01

Previously reported self-cloning procedures for breeding of industrial yeast strains require DNA from other strains, plasmid DNA, or mutagenesis. Therefore, we aimed to construct a self-cloning baker's yeast strain that exhibits freeze tolerance via an improved self-cloning procedure. We first disrupted the URA3 gene of a prototrophic baker's yeast strain without the use of any marker gene, resulting in a Δura3 homozygous disruptant. Then, the URA3 gene of the parental baker's yeast strain was used as a selection marker to introduce the constitutive TDH3 promoter upstream of the PDE2 gene encoding high-affinity cyclic AMP phosphodiesterase. This self-cloning procedure was performed without using DNA from other Saccharomyces cerevisiae strains, plasmid DNA, or mutagenesis and was therefore designated an intra-strain self-cloning procedure. Using this self-cloning procedure, we succeeded in producing self-cloning baker's yeast strains that harbor the TDH3p-PDE2 gene heterozygously and homozygously, designated TDH3p-PDE2 hetero and TDH3p-PDE2 homo strains, respectively. These self-cloning strains expressed much higher levels of PDE2 mRNA than the parental strain and exhibited higher viability after freeze stress, as well as higher fermentation ability in frozen dough, when compared with the parental strain. The TDH3p-PDE2 homo strain was genetically more stable than the TDH3p-PDE2 hetero strain. These results indicate that both heterozygous and homozygous strains of self-cloning PDE2-overexpressing freeze-tolerant strains of industrial baker's yeast can be prepared using the intra-strain self-cloning procedure, and, from a practical viewpoint, the TDH3p-PDE2 homo strain constructed in this study is preferable to the TDH3p-PDE2 hetero strain for frozen dough baking. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.
Remanence and survival of commercial yeast in different ecological niches of the vineyard.

PubMed

Cordero-Bueso, Gustavo; Arroyo, Teresa; Serrano, Ana; Valero, Eva

2011-08-01

The use of commercial wine yeast strains as starters has been grown extensively over the past three decades. Wine yeasts are annually released in winery environments; however, little is known about the fate of these strains in the vineyard. To evaluate the industrial starter yeasts' ability to survive in nature and become part of the natural microbiota of musts, commercial yeast was disseminated voluntarily in an experimental vineyard in the Madrid region (Spain). A large sampling plan was devised over 3 years, including samples of grapes, leaves, bark and soil. The disseminated yeast was well represented in the vineyard during the first 8 months. After 2 years, the commercial yeast strain had not survived in the sprayed plants, but a residual population was found in plants situated 50 m east of the sprayed area. After 3 years, commercial yeast disseminated was not found in the sampled vineyard. Grapes and soil showed the highest number of yeasts isolated in the vegetative period, the bark being the main natural reservoir during the resting stages. The result of analysis of population variations from year to year indicated that permanent implantation of commercial strain (K1M) in the vineyard did not occur and its presence was limited in time. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
Evaluation of the Microbial Identification System for identification of clinically isolated yeasts.

PubMed Central

Crist, A E; Johnson, L M; Burke, P J

1996-01-01

The Microbial Identification System (MIS; Microbial ID, Inc., Newark, Del.) was evaluated for the identification of 550 clinically isolated yeasts. The organisms evaluated were fresh clinical isolates identified by methods routinely used in our laboratory (API 20C and conventional methods) and included Candida albicans (n = 294), C. glabrata (n = 145), C. tropicalis (n = 58), C. parapsilosis (n = 33), and other yeasts (n = 20). In preparation for fatty acid analysis, yeasts were inoculated onto Sabouraud dextrose agar and incubated at 28 degrees C for 24 h. Yeasts were harvested, saponified, derivatized, and extracted, and fatty acid analysis was performed according to the manufacturer's instructions. Fatty acid profiles were analyzed, and computer identifications were made with the Yeast Clinical Library (database version 3.8). Of the 550 isolates tested, 374 (68.0%) were correctly identified to the species level, with 87 (15.8%) being incorrectly identified and 89 (16.2%) giving no identification. Repeat testing of isolates giving no identification resulted in an additional 18 isolates being correctly identified. This gave the MIS an overall identification rate of 71.3%. The most frequently misidentified yeast was C. glabrata, which was identified as Saccharomyces cerevisiae 32.4% of the time. On the basis of these results, the MIS, with its current database, does not appear suitable for the routine identification of clinically important yeasts. PMID:8880489
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.
High-performance TiO(2) from Baker's yeast.

PubMed

He, Wen; Cui, Jingjie; Yue, Yuanzheng; Zhang, Xudong; Xia, Xi; Liu, Hong; Lui, Suwen

2011-02-01

Based on the biomineralization assembly concept, a biomimetic approach has been developed to synthesize high-performance mesoporous TiO(2). The key step of this approach is to apply Baker's yeast cells as biotemplates for deriving the hierarchically ordered mesoporous anatase structure. The mechanism of formation of the yeast-TiO(2) is revealed by characterizing its morphology, microstructure, and chemical composition. The yeast-TiO(2) exhibits outstanding photocatalytic performance. Under visible-light irradiation, the removal efficiency of chemical oxygen demand (COD) and color of the paper industry wastewater has reached 80.3% and nearly 100%, respectively. The approach may open new vistas for fabricating advanced mesoporous materials under ambient condition. Copyright © 2010 Elsevier Inc. All rights reserved.
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
Denaturing gradient gel electrophoresis profiles of bacteria from the saliva of twenty four different individuals form clusters that showed no relationship to the yeasts present.

PubMed

M Weerasekera, Manjula; H Sissons, Chris; Wong, Lisa; A Anderson, Sally; R Holmes, Ann; D Cannon, Richard

2017-10-01

The aim was to investigate the relationship between groups of bacteria identified by cluster analysis of the DGGE fingerprints and the amounts and diversity of yeast present. Bacterial and yeast populations in saliva samples from 24 adults were analysed using denaturing gradient gel electrophoresis (DGGE) of the bacteria present and by yeast culture. Eubacterial DGGE banding patterns showed considerable variation between individuals. Seventy one different amplicon bands were detected, the band number per saliva sample ranged from 21 to 39 (mean±SD=29.3±4.9). Cluster and principal component analysis of the bacterial DGGE patterns yielded three major clusters containing 20 of the samples. Seventeen of the 24 (71%) saliva samples were yeast positive with concentrations up to 10 3 cfu/mL. Candida albicans was the predominant species in saliva samples although six other yeast species, including Candida dubliniensis, Candida tropicalis, Candida krusei, Candida guilliermondii, Candida rugosa and Saccharomyces cerevisiae, were identified. The presence, concentration, and species of yeast in samples showed no clear relationship to the bacterial clusters. Despite indications of in vitro bacteria-yeast interactions, there was a lack of association between the presence, identity and diversity of yeasts and the bacterial DGGE fingerprint clusters in saliva. This suggests significant ecological individual-specificity of these associations in highly complex in vivo oral biofilm systems under normal oral conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modification of the feeding behavior of dairy cows through live yeast supplementation.

PubMed

DeVries, T J; Chevaux, E

2014-10-01

The objective of this study was to determine if the feeding behavior of dairy cows is modified through live yeast supplementation. Twelve lactating Holstein dairy cows (2 primiparous and 10 multiparous) were individually exposed, in a replicated crossover design, to each of 2 treatment diets (over 35-d periods): (1) a control TMR and (2) a control TMR plus 1 × 10(10) cfu/head per day of live yeast (Saccharomyces cerevisiae CNCM I-1077; Levucell SC20; Lallemand Animal Nutrition, Montreal, QC, Canada). Milk production, feeding, and rumination behavior were electronically monitored for each animal for the last 7 d of each treatment period. Milk samples were collected for the last 6 d of each period for milk component analysis. Dry matter intake (28.3 kg/d), eating time (229.3 min/d), and rate (0.14 kg of dry matter/min) were similar between treatments. With yeast supplementation, meal criteria (minimum intermeal interval) were shorter (20.0 vs. 25.8 min), translating to cows tending to have more meals (9.0 vs. 7.8 meals/d), which tended to be smaller in size (3.4 vs. 3.8 kg/meal). Yeast-supplemented cows also tended to ruminate longer (570.3 vs. 544.9 min/d). Milk yield (45.8 kg/d) and efficiency of production (1.64 kg of milk/kg of dry matter intake) were similar between treatments. A tendency for higher milk fat percent (3.71 vs. 3.55%) and yield (1.70 vs. 1.63 kg/d) was observed when cows were supplemented with yeast. No differences in milk fatty acid composition were observed, with the exception of a tendency for a greater concentration of 18:2 cis-9,cis-12 fatty acid (2.71 vs. 2.48% of total fatty acids) with yeast supplementation. Yeast-supplemented cows had lower mean ruminal temperature (38.4 vs. 38.5 °C) and spent less time with rumen temperature above 39.0 °C (353.1 vs. 366.9 min/d), potentially indicating improved rumen pH conditions. Overall, the results show that live yeast supplementation tended to improve meal patterns and rumination, rumen
House microbiotas as sources of lactic acid bacteria and yeasts in traditional Italian sourdoughs.

PubMed

Minervini, Fabio; Lattanzi, Anna; De Angelis, Maria; Celano, Giuseppe; Gobbetti, Marco

2015-12-01

This study aimed at understanding the extent of contamination by lactic acid bacteria (LAB) and yeasts from the house microbiotas during sourdough back-slopping. Besides sourdoughs, wall, air, storage box, dough mixer and flour of four bakeries were analyzed. Based on plate counts, LAB and yeasts dominated the house microbiota. Based on high throughput sequencing of the 16S rRNA genes, flour harbored the highest number of Firmicutes, but only few of them adapted to storage box, dough mixer and sourdough. Lactobacillus sanfranciscensis showed the highest abundance in dough mixer and sourdoughs. Lactobacillus plantarum persisted only in storage box, dough mixer and sourdough of two bakeries. Weissella cibaria also showed higher adaptability in sourdough than in bakery equipment, suggesting that flour is the main origin of this species. Based on 18S rRNA data, Saccharomyces cerevisiae was the dominant yeast in house and sourdough microbiotas, excepted one bakery dominated by Kazachstania exigua. The results of this study suggest that the dominant species of sourdough LAB and yeasts dominated also the house microbiota. Copyright © 2015 Elsevier Ltd. All rights reserved.
The effects of live yeast Saccharomyces cerevisiae on postweaning diarrhea, immune response, and growth performance in weaned piglets.

PubMed

Trckova, M; Faldyna, M; Alexa, P; Sramkova Zajacova, Z; Gopfert, E; Kumprechtova, D; Auclair, E; D'Inca, R

2014-02-01

The effects of live yeast Saccharomyces cerevisiae (strain CNCM I-4407, 10(10) cfu/g; Actisaf; Lesaffre Feed Additives, Marcq-en-Baroeul, France) on the severity of diarrhea, immune response, and growth performance in weaned piglets orally challenged with enterotoxigenic Escherichia coli (ETEC) strain O149:K88 were investigated. Live yeast was fed to sows and their piglets in the late gestation, suckling, and postweaning periods. Sows were fed a basal diet without (Control; n = 2) or with (Supplemented; n = 2) 1 g/kg of live yeast from d 94 of gestation and during lactation until weaning of the piglets (d 28). Suckling piglets of the supplemented sows were orally treated with 1 g of live yeast in porridge carrier 3 times a week until weaning. Weaned piglets were fed a basal starter diet without (Control; n = 19) or with (Supplemented; n = 15) 5 g of live yeast/kg feed for 2 wk. Significantly lower daily diarrhea scores (P < 0.05), duration of diarrhea (P < 0.01), and shedding of pathogenic ETEC bacteria (P < 0.05) in feces was detected in the supplemented piglets. Administration of live yeast significantly increased (P < 0.05) IgA levels in the serum of piglets. Evidence indicates that decreased infection-related stress and severity of diarrhea in yeast-fed weaned piglets positively affected their growth capacity in the postweaning period (P < 0.05). The results suggest that dietary supplementation with live yeast S. cerevisiae to sows and piglets in the late gestation, suckling, and postweaning periods can be useful in the reduction of the duration and severity of postweaning diarrhea caused by ETEC.
Yeasts as distinct life forms of fungi

USDA-ARS?s Scientific Manuscript database

This review describes all presently recognized genera of the Ascomycete yeasts (Saccharomycotina, budding yeasts, and the Taphrinomycotina, fission yeasts and related) as well as all currently recognized genera of the Basidiomycete yeasts. This update will be the lead chapter for a book entitled “Ye...
Study of amyloids using yeast

PubMed Central

Wickner, Reed B.; Kryndushkin, Dmitry; Shewmaker, Frank; McGlinchey, Ryan; Edskes, Herman K.

2012-01-01

Summary Saccharomyces cerevisiae has been a useful model organism in such fields as the cell cycle, regulation of transcription, protein trafficking and cell biology, primarily because of its ease of genetic manipulation. This is no less so in the area of amyloid studies. The endogenous yeast amyloids described to date include prions, infectious proteins (Table 1), and some cell wall proteins (1). and amyloids of humans and a fungal prion have also been studied using the yeast system. Accordingly, the emphasis of this chapter will be on genetic, biochemical, cell biological and physical methods particularly useful in the study of yeast prions and other amyloids studied in yeast. We limit our description of these methods to those aspects which have been most useful in studying yeast prions, citing more detailed expositions in the literature. Volumes on yeast genetics methods (2–4), and on amyloids and prions (5, 6) are useful, and Masison has edited a volume of Methods on “Identification, analysis and characterization of fungal prions” which covers some of this territory (7). We also outline some useful physical methods, pointing the reader to more extensive and authoratative descriptions. PMID:22528100
Fission yeast Ags1 confers the essential septum strength needed for safe gradual cell abscission

PubMed Central

Sato, Mamiko; Muñoz, Javier; Moreno, M. Belén; Clemente-Ramos, Jose Angel; Ramos, Mariona; Okada, Hitoshi; Osumi, Masako; Durán, Angel; Ribas, Juan Carlos

2012-01-01

Fungal cytokinesis requires the assembly of a dividing septum wall. In yeast, the septum has to be selectively digested during the critical cell separation process. Fission yeast cell wall α(1-3)glucan is essential, but nothing is known about its localization and function in the cell wall or about cooperation between the α- and β(1-3)glucan synthases Ags1 and Bgs for cell wall and septum assembly. Here, we generate a physiological Ags1-GFP variant and demonstrate a tight colocalization with Bgs1, suggesting a cooperation in the important early steps of septum construction. Moreover, we define the essential functions of α(1-3)glucan in septation and cell separation. We show that α(1-3)glucan is essential for both secondary septum formation and the primary septum structural strength needed to support the physical forces of the cell turgor pressure during cell separation. Consequently, the absence of Ags1 and therefore α(1-3)glucan generates a special and unique side-explosive cell separation due to an instantaneous primary septum tearing caused by the turgor pressure. PMID:22891259
Eighteen new oleaginous yeast species.

PubMed

Garay, Luis A; Sitepu, Irnayuli R; Cajka, Tomas; Chandra, Idelia; Shi, Sandy; Lin, Ting; German, J Bruce; Fiehn, Oliver; Boundy-Mills, Kyria L

2016-07-01

Of 1600 known species of yeasts, about 70 are known to be oleaginous, defined as being able to accumulate over 20 % intracellular lipids. These yeasts have value for fundamental and applied research. A survey of yeasts from the Phaff Yeast Culture Collection, University of California Davis was performed to identify additional oleaginous species within the Basidiomycota phylum. Fifty-nine strains belonging to 34 species were grown in lipid inducing media, and total cell mass, lipid yield and triacylglycerol profiles were determined. Thirty-two species accumulated at least 20 % lipid and 25 species accumulated over 40 % lipid by dry weight. Eighteen of these species were not previously reported to be oleaginous. Triacylglycerol profiles were suitable for biodiesel production. These results greatly expand the number of known oleaginous yeast species, and reveal the wealth of natural diversity of triacylglycerol profiles within wild-type oleaginous Basidiomycetes.
Drying enhances immunoactivity of spent brewer's yeast cell wall β-D-glucans.

PubMed

Liepins, Janis; Kovačova, Elena; Shvirksts, Karlis; Grube, Mara; Rapoport, Alexander; Kogan, Grigorij

2015-07-20

Due to immunological activity, microbial cell wall polysaccharides are defined as 'biological response modifiers' (BRM). Cell walls of spent brewer's yeast also have some BRM activity. However, up to date there is no consensus on the use of spent brewer's yeast D-glucan as specific BRM in humans or animals. The aim of this paper is to demonstrate the potential of spent brewer's yeast β-D-glucans as BRM, and drying as an efficient pretreatment to increase β-D-glucan's immunogenic activity. Our results revealed that drying does not change spent brewer's yeast biomass carbohydrate content as well as the chemical structure of purified β-D-glucan. However, drying increased purified β-D-glucan TNF-α induction activity in the murine macrophage model. We presume drying pretreatment enhances purity of extracted β-D-glucan. This is corroborated with FT-IR analyses of the β-D-glucan spectra. Based on our results, we suggest that dry spent brewer's yeast biomass can be used as a cheap source for high-quality β-D-glucan extraction. Drying in combination with carboxylmethylation (CM), endows spent brewer's yeast β-D-glucan with the immunoactivity similar or exceeding that of a well-characterized fungal BRM pleuran. Copyright © 2015 Elsevier B.V. All rights reserved.
Culex pipiens Development Is Greatly Influenced by Native Bacteria and Exogenous Yeast

PubMed Central

Díaz-Nieto, Leonardo M.; D´Alessio, Cecilia

2016-01-01

Culex pipiens is the most cosmopolitan mosquito of the Pipiens Assemblage. By studying the nature of interactions between this species and microorganisms common to its breeding environment we can unravel important pitfalls encountered during development. We tested the survival rate of larval stages, pupae and adults of a Cx. pipiens colony exposed to a variety of microorganisms in laboratory conditions and assessed the transmission to offspring (F1) by those organisms that secured development up to adulthood. Three complementary experiments were designed to: 1) explore the nutritional value of yeasts and other microorganisms during Cx. pipiens development; 2) elucidate the transstadial transmission of yeast to the host offspring; and 3) to examine the relevance of all these microorganisms in female choice for oviposition-substratum. The yeast Saccharomyces cerevisiae proved to be the most nutritional diet, but despite showing the highest survival rates, vertical transmission to F1 was never confirmed. In addition, during the oviposition trials, none of the gravid females was attracted to the yeast substratum. Notably, the two native bacterial strains, Klebsiella sp. and Aeromonas sp., were the preferred oviposition media, the same two bacteria that managed to feed neonates until molting into 2nd instar larvae. Our results not only suggest that Klebsiella sp. or Aeromonas sp. serve as attractants for oviposition habitat selection, but also nurture the most fragile instar, L1, to assure molting into a more resilient stage, L2, while yeast proves to be the most supportive diet for completing development. These experiments unearthed survival traits that might be considered in the future development of strategies of Cx. pipiens control. These studies can be extended to other members of the Pipiens Assemblage. PMID:27055276
Get Important Shots

MedlinePlus

... checkup. Make a plan with your doctor or nurse to get the shots you need. You may also be able to get shots at your local pharmacy. Use this vaccine clinic locator to find out where you can get important shots. Get a seasonal flu shot every year. Remember, everyone age 6 months ...
"Omics" of Selenium Biology: A Prospective Study of Plasma Proteome Network Before and After Selenized-Yeast Supplementation in Healthy Men.

PubMed

Sinha, Indu; Karagoz, Kubra; Fogle, Rachel L; Hollenbeak, Christopher S; Zea, Arnold H; Arga, Kazim Y; Stanley, Anne E; Hawkes, Wayne C; Sinha, Raghu

2016-04-01

Low selenium levels have been linked to a higher incidence of cancer and other diseases, including Keshan, Chagas, and Kashin-Beck, and insulin resistance. Additionally, muscle and cardiovascular disorders, immune dysfunction, cancer, neurological disorders, and endocrine function have been associated with mutations in genes encoding for selenoproteins. Selenium biology is complex, and a systems biology approach to study global metabolomics, genomics, and/or proteomics may provide important clues to examining selenium-responsive markers in circulation. In the current investigation, we applied a global proteomics approach on plasma samples collected from a previously conducted, double-blinded placebo controlled clinical study, where men were supplemented with selenized-yeast (Se-Yeast; 300 μg/day, 3.8 μmol/day) or placebo-yeast for 48 weeks. Proteomic analysis was performed by iTRAQ on 8 plasma samples from each arm at baseline and 48 weeks. A total of 161 plasma proteins were identified in both arms. Twenty-two proteins were significantly altered following Se-Yeast supplementation and thirteen proteins were significantly changed after placebo-yeast supplementation in healthy men. The differentially expressed proteins were involved in complement and coagulation pathways, immune functions, lipid metabolism, and insulin resistance. Reconstruction and analysis of protein-protein interaction network around selected proteins revealed several hub proteins. One of the interactions suggested by our analysis, PHLD-APOA4, which is involved in insulin resistance, was subsequently validated by Western blot analysis. Our systems approach illustrates a viable platform for investigating responsive proteomic profile in 'before and after' condition following Se-Yeast supplementation. The nature of proteins identified suggests that selenium may play an important role in complement and coagulation pathways, and insulin resistance.
[Onychomycosis by yeast not common in diabetics of a health center].

PubMed

Imbert, J L; G Gomez, J V; Escudero, R B; Blasco, J L

2016-10-01

Mexican diabetic population frequently presents mycosis under foot hyperkeratosis; however, in another type of onychomycosis as the ones that is assumed Candida albicans is the causal agent, it is unknown the frequency, the prevalence and if another Candida species or other yeasts are found. Evaluate the frequency of yeasts causing onychomycosis in diabetic patients looked after in public institutions of health of the State of Hidalgo, Mexico, and its association with clinical epidemiological variables. An observational, descriptive and transversal study was made on 261 patients, from which one nail sample of each one was obtained, used to isolate and identify dermatophytes and yeasts; the results were statistically correlated with 24 epidemiological parameters. The clinical study was done through interrogation and by medical exploration in order to evaluate Tinea pedis and onychomycosis. Onychomycosis were caused by Candida guilliermondii, Candida parapsilosis, Candida glabrata, Candida krusei, Candida spp., Kodamaea ohmeri, Prototheca wickerhamii and unidentified yeasts. The prevalence for general onychomycosis, by dermatophytes, mixed onychomycosis and by yeasts were: 24.1, 19.5, 2.3 and 14.6%, respectively. Patients with significant probability to be diagnosed as having onychomycosis by yeasts are those wearing open shoes (2.59%); technicians and professionals (10.49%) and alcohol drinkers (3.72%). The fact that Candida albicans is not present in this study as causal agent of onychomycosis, and emerging and non-common yeasts were indeed isolated, creates new challenges. It is remarked the clinical criterion that when onychomycosis is suspected in diabetics, the diagnosis for culturing dermatophytes and yeasts should be included. Copyright © 2015 Sociedad Española de Médicos de Atención Primaria (SEMERGEN). Publicado por Elsevier España, S.L.U. All rights reserved.
THE ROLE FUNGI AND YEAST IN MONITORED NATURAL ATTENUATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brigmon, R.; Abe, M.; Johnson, B.

Fungi and yeast have been characterized as important components in the bioremediation of organic contaminants in soil and water including polyaromatic hydrocarbons (PAHs); however, research into their ability to metabolize these compounds in extreme environments has been limited. In this work forty-three fungi and yeasts were isolated from a PAH-contaminated sludge waste lagoon in Poland. The lagoon was part of a monitored natural attenuation (MNA) study where natural reduction of PAHs and associated toxicity over time in non-disturbed areas of the sludge lagoon indicated MNA activity. The microorganisms were initially isolated on minimal medium containing naphthalene as the sole carbonmore » and energy source. Fungal isolates were then maintained on MEA and identified based on microscopic examination and BIOLOG{reg_sign}. The analysis identified several of the fungal isolates as belonging to the genera Penicillium, Paecilomyces, Aspergillus, and Eupenicillium. Yeasts included Candida parapsilosis and C. fluvialitis. Further microbial characterization revealed that several isolates were capable of rowing on acidified media of pH 4, 3, and 2.5. Over twenty percent of the fungi demonstrated growth as low as pH 2.5. Of the 43 isolates examined, 24 isolates exhibited growth at 5 C. Nine of the fungal isolates exhibiting growth at 5 C were then examined for metabolic activity using a respirometer testing metabolic activity at pH 3. Microcosm studies confirmed the growth of the fungi on PAH contaminated sediment as the sole carbon and energy source with elevated metabolic rates indicating evidence of MNA. Our findings suggest that many of the Poland fungal isolates may be of value in the bioremediation processes in acidic waste sites in northern climates typical of Northern Europe.« less
Detection of Protein Interactions in T3S Systems Using Yeast Two-Hybrid Analysis.

PubMed

Nilles, Matthew L

2017-01-01

Two-hybrid systems, sometimes termed interaction traps, are genetic systems designed to find and analyze interactions between proteins. The most common systems are yeast based (commonly Saccharomyces cerevisae) and rely on the functional reconstitution of the GAL4 transcriptional activator. Reporter genes, such as the lacZ gene of Escherichia coli (encodes β-galactosidase), are placed under GAL4-dependent transcriptional control to provide quick and reliable detection of protein interactions. In this method the use of a yeast-based two-hybrid system is described to study protein interactions between components of type III secretion systems.
Defective quiescence entry promotes the fermentation performance of bottom-fermenting brewer's yeast.

PubMed

Oomuro, Mayu; Kato, Taku; Zhou, Yan; Watanabe, Daisuke; Motoyama, Yasuo; Yamagishi, Hiromi; Akao, Takeshi; Aizawa, Masayuki

2016-11-01

One of the key processes in making beer is fermentation. In the fermentation process, brewer's yeast plays an essential role in both the production of ethanol and the flavor profile of beer. Therefore, the mechanism of ethanol fermentation by of brewer's yeast is attracting much attention. The high ethanol productivity of sake yeast has provided a good basis from which to investigate the factors that regulate the fermentation rates of brewer's yeast. Recent studies found that the elevated fermentation rate of sake Saccharomyces cerevisiae species is closely related to a defective transition from vegetative growth to the quiescent (G 0 ) state. In the present study, to clarify the relationship between the fermentation rate of brewer's yeast and entry into G 0 , we constructed two types of mutant of the bottom-fermenting brewer's yeast Saccharomyces pastorianus Weihenstephan 34/70: a RIM15 gene disruptant that was defective in entry into G 0 ; and a CLN3ΔPEST mutant, in which the G 1 cyclin Cln3p accumulated at high levels. Both strains exhibited higher fermentation rates under high-maltose medium or high-gravity wort conditions (20° Plato) as compared with the wild-type strain. Furthermore, G 1 arrest and/or G 0 entry were defective in both the RIM15 disruptant and the CLN3ΔPEST mutant as compared with the wild-type strain. Taken together, these results indicate that regulation of the G 0 /G 1 transition might govern the fermentation rate of bottom-fermenting brewer's yeast in high-gravity wort. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.
Biomedical applications of yeast- a patent view, part one: yeasts as workhorses for the production of therapeutics and vaccines.

PubMed

Roohvand, Farzin; Shokri, Mehdi; Abdollahpour-Alitappeh, Meghdad; Ehsani, Parastoo

2017-08-01

Yeasts, as Eukaryotes, offer unique features for ease of growth and genetic manipulation possibilities, making it an exceptional microbial host. Areas covered: This review provides general and patent-oriented insights into production of biopharmaceuticals by yeasts. Patents, wherever possible, were correlated to the original or review articles. The review describes applications of major GRAS (generally regarded as safe) yeasts for the production of therapeutic proteins and subunit vaccines; additionally, immunomodulatory properties of yeast cell wall components were reviewed for use of whole yeast cells as a new vaccine platform. The second part of the review will discuss yeast- humanization strategies and innovative applications. Expert opinion: Biomedical applications of yeasts were initiated by utilization of Saccharomyces cerevisiae, for production of leavened (fermented) products, and advanced to serve to produce biopharmaceuticals. Higher biomass production and expression/secretion yields, more similarity of glycosylation patterns to mammals and possibility of host-improvement strategies through application of synthetic biology might enhance selection of Pichia pastoris (instead of S. cerevisiae) as a host for production of biopharmaceutical in future. Immunomodulatory properties of yeast cell wall β-glucans and possibility of intracellular expression of heterologous pathogen/tumor antigens in yeast cells have expanded their application as a new platform, 'Whole Yeast Vaccines'.
Self-cloning baker's yeasts that accumulate proline enhance freeze tolerance in doughs.

PubMed

Kaino, Tomohiro; Tateiwa, Tetsuya; Mizukami-Murata, Satomi; Shima, Jun; Takagi, Hiroshi

2008-09-01

We constructed self-cloning diploid baker's yeast strains by disrupting PUT1, encoding proline oxidase, and replacing the wild-type PRO1, encoding gamma-glutamyl kinase, with a pro1(D154N) or pro1(I150T) allele. The resultant strains accumulated intracellular proline and retained higher-level fermentation abilities in the frozen doughs than the wild-type strain. These results suggest that proline-accumulating baker's yeast is suitable for frozen-dough baking.
Nutrient supplements boost yeast transformation efficiency

PubMed Central

Yu, Sheng-Chun; Dawson, Alexander; Henderson, Alyssa C.; Lockyer, Eloise J.; Read, Emily; Sritharan, Gayathri; Ryan, Marjah; Sgroi, Mara; Ngou, Pok M.; Woodruff, Rosie; Zhang, Ruifeng; Ren Teen Chia, Travis; Liu, Yu; Xiang, Yiyu; Spanu, Pietro D.

2016-01-01

Efficiency of yeast transformation is determined by the rate of yeast endocytosis. The aim of this study was to investigate the effect of introducing amino acids and other nutrients (inositol, adenine, or p-aminobenzoic acid) in the transformation medium to develop a highly efficient yeast transformation protocol. The target of rapamycin complex 1 (TORC1) kinase signalling complex influences the rate of yeast endocytosis. TORC signaling is induced by amino acids in the media. Here, we found that increasing the concentration of amino acids and other nutrients in the growth media lead to an increase yeast transformation efficiency up to 107 CFU per μg plasmid DNA and per 108 cells with a 13.8 kb plasmid DNA. This is over 130 times that of current published methods. This improvement may facilitate more efficient experimentation in which transformation efficiency is critical, such as yeast two-hybrid screening. PMID:27760994
Effects of metal salt catalysts on yeast cell growth in ethanol conversion

Treesearch

Chung-Yun Hse; Yin Lin

2009-01-01

The effects of the addition of metal salts and metal salt-catalyzed hydrolyzates on yeast cell growth in ethanol fermentation were investigated. Four yeast strains (Saccharomyces cerevisiae WT1, Saccharomyces cerevisiae MT81, Candida sp. 1779, and Klumaromyces fragilis), four metal salts (CuCl2, FeCl3, AgNO3, and I2), two metal salt-catalyzed hydrolyzates (...
Evolution of cyclin-dependent kinases (CDKs) and CDK-activating kinases (CAKs): differential conservation of CAKs in yeast and metazoa.

PubMed

Liu, J; Kipreos, E T

2000-07-01

Cyclin-dependent kinases (CDKs) function as central regulators of both the cell cycle and transcription. CDK activation depends on phosphorylation by a CDK-activating kinase (CAK). Different CAKs have been identified in budding yeast, fission yeast, and metazoans. All known CAKs belong to the extended CDK family. The sole budding yeast CAK, CAK1, and one of the two CAKs in fission yeast, csk1, have diverged considerably from other CDKs. Cell cycle regulatory components have been largely conserved in eukaryotes; however, orthologs of neither CAK1 nor csk1 have been identified in other species to date. To determine the evolutionary relationships of yeast and metazoan CAKs, we performed a phylogenetic analysis of the extended CDK family in budding yeast, fission yeast, humans, the fruit fly Drosophila melanogaster, and the nematode Caenorhabditis elegans. We observed that there were 10 clades for CDK-related genes, of which seven appeared ancestral, containing both yeast and metazoan genes. The four clades that contain CDKs that regulate transcription by phosphorylating the carboxyl-terminal domain (CTD) of RNA Polymerase II generally have only a single orthologous gene in each species of yeast and metazoans. In contrast, the ancestral cell cycle CDK (analogous to budding yeast CDC28) gave rise to a number of genes in metazoans, as did the ancestor of budding yeast PHO85. One ancestral clade is unique in that there are fission yeast and metazoan members, but there is no budding yeast ortholog, suggesting that it was lost subsequent to evolutionary divergence. Interestingly, CAK1 and csk1 branch together with high bootstrap support values. We used both the relative apparent synapomorphy analysis (RASA) method in combination with the S-F method of sampling reduced character sets and gamma-corrected distance methods to confirm that the CAK1/csk1 association was not an artifact of long-branch attraction. This result suggests that CAK1 and csk1 are orthologs and that a

Culture medium optimization for osmotolerant yeasts by use of a parallel fermenter system and rapid microbiological testing.

PubMed

Pfannebecker, Jens; Schiffer-Hetz, Claudia; Fröhlich, Jürgen; Becker, Barbara

2016-11-01

In the present study, a culture medium for qualitative detection of osmotolerant yeasts, named OM, was developed. For the development, culture media with different concentrations of glucose, fructose, potassium chloride and glycerin were analyzed in a Biolumix™ test incubator. Selectivity for osmotolerant yeasts was guaranteed by a water activity (a w )-value of 0.91. The best results regarding fast growth of Zygosaccharomyces rouxii (WH 1002) were achieved in a culture medium consisting of 45% glucose, 5% fructose and 0.5% yeast extract and in a medium with 30% glucose, 10% glycerin, 5% potassium chloride and 0.5% yeast extract. Substances to stimulate yeast fermentation rates were analyzed in a RAMOS ® parallel fermenter system, enabling online measurement of the carbon dioxide transfer rate (CTR) in shaking flasks. Significant increases of the CTR was achieved by adding especially 0.1-0.2% ammonium salts ((NH 4 ) 2 HPO 4 , (NH 4 ) 2 SO 4 or NH 4 NO 3 ), 0.5% meat peptone and 1% malt extract. Detection times and the CTR of 23 food-borne yeast strains of the genera Zygosaccharomyces, Torulaspora, Schizosaccharomyces, Candida and Wickerhamomyces were analyzed in OM bouillon in comparison to the selective culture media YEG50, MYG50 and DG18 in the parallel fermenter system. The OM culture medium enabled the detection of 10 2 CFU/g within a time period of 2-3days, depending on the analyzed yeast species. Compared with YEG50 and MYG50 the detection times could be reduced. As an example, W. anomalus (WH 1021) was detected after 124h in YEG50, 95.5h in MYG50 and 55h in OM bouillon. Compared to YEG50 the maximum CO 2 transfer rates for Z. rouxii (WH 1001), T. delbrueckii (DSM 70526), S. pombe (DSM 70576) and W. anomalus (WH 1016) increased by a factor ≥2.6. Furthermore, enrichment cultures of inoculated high-sugar products in OM culture medium were analyzed in the Biolumix™ system. The results proved that detection times of 3days for Z. rouxii and T. delbrueckii
Culturable yeasts in meltwaters draining from two glaciers in the Italian Alps

NASA Astrophysics Data System (ADS)

Buzzini, Pietro; Turchetti, Benedetta; Diolaiuti, Guglielmina; D'Agata, Carlo; Martini, Alessandro; Smiraglia, Claudio

The meltwaters draining from two glaciers in the Italian Alps contain metabolically active yeasts isolable by culture-based laboratory procedures. The average number of culturable yeast cells in the meltwaters was 10 20 colony-forming units (CFU) L-1, whereas supraglacial stream waters originating from overlying glacier ice contained <1 CFU L-1. Yeast cell number increased as the suspended-sediment content of the water samples increased. Basidiomycetous yeasts represent >80% of isolated strains (Cryptococcus spp. and Rhodotorula spp. were 33.3% and 17.8% of total strains, respectively). Culturable yeasts were psychrotolerant, predominantly obligate aerobes and able to degrade organic macromolecules (e.g. starch, esters, lipids, proteins). To the authors' knowledge, this is the first study to report the presence of culturable yeasts in meltwaters originating from glaciers. On the basis of these results, it is reasonable to suppose that the viable yeasts observed in meltwaters derived predominantly from the subglacial zone and that they originated from the subglacial microbial community. Their metabolic abilities could contribute to the microbial activity occurring in subglacial environments.
Independent Origins of Yeast Associated with Coffee and Cacao Fermentation.

PubMed

Ludlow, Catherine L; Cromie, Gareth A; Garmendia-Torres, Cecilia; Sirr, Amy; Hays, Michelle; Field, Colburn; Jeffery, Eric W; Fay, Justin C; Dudley, Aimée M

2016-04-04

Modern transportation networks have facilitated the migration and mingling of previously isolated populations of plants, animals, and insects. Human activities can also influence the global distribution of microorganisms. The best-understood example is yeasts associated with winemaking. Humans began making wine in the Middle East over 9,000 years ago [1, 2]. Selecting favorable fermentation products created specialized strains of Saccharomyces cerevisiae [3, 4] that were transported along with grapevines. Today, S. cerevisiae strains residing in vineyards around the world are genetically similar, and their population structure suggests a common origin that followed the path of human migration [3-7]. Like wine, coffee and cacao depend on microbial fermentation [8, 9] and have been globally dispersed by humans. Theobroma cacao originated in the Amazon and Orinoco basins of Colombia and Venezuela [10], was cultivated in Central America by Mesoamerican peoples, and was introduced to Europeans by Hernán Cortés in 1530 [11]. Coffea, native to Ethiopia, was disseminated by Arab traders throughout the Middle East and North Africa in the 6(th) century and was introduced to European consumers in the 17(th) century [12]. Here, we tested whether the yeasts associated with coffee and cacao are genetically similar, crop-specific populations or genetically diverse, geography-specific populations. Our results uncovered populations that, while defined by niche and geography, also bear signatures of admixture between major populations in events independent of the transport of the plants. Thus, human-associated fermentation and migration may have affected the distribution of yeast involved in the production of coffee and chocolate. Copyright © 2016 Elsevier Ltd. All rights reserved.
Virgin olive oil yeasts: A review.

PubMed

Ciafardini, Gino; Zullo, Biagi Angelo

2018-04-01

This review summarizes current knowledge on virgin olive oil yeasts. Newly produced olive oil contains solid particles and micro drops of vegetation water in which yeasts reproduce to become the typical microbiota of olive oil. To date, about seventeen yeast species have been isolated from different types of olive oils and their by-products, of which six species have been identified as new species. Certain yeast species contribute greatly to improving the sensorial characteristics of the newly produced olive oil, whereas other species are considered harmful as they can damage the oil quality through the production of unpleasant flavors and triacylglycerol hydrolysis. Studies carried out in certain yeast strains have demonstrated the presence of defects in olive oil treated with Candida adriatica, Nakazawaea wickerhamii and Candida diddensiae specific strains, while other olive oil samples treated with other Candida diddensiae strains were defect-free after four months of storage and categorized as extra virgin. A new acetic acid producing yeast species, namely, Brettanomyces acidodurans sp. nov., which was recently isolated from olive oil, could be implicated in the wine-vinegary defect of the product. Other aspects related to the activity of the lipase-producing yeasts and the survival of the yeast species in the flavored olive oils are also discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.
F-box proteins Pof3 and Pof1 regulate Wee1 degradation and mitotic entry in fission yeast.

PubMed

Qiu, Cui; Yi, Yuan-Yuan; Lucena, Rafael; Wu, Meng-Juan; Sun, Jia-Hao; Wang, Xi; Jin, Quan-Wen; Wang, Yamei

2018-02-02

The key cyclin-dependent kinase Cdk1 (Cdc2) promotes irreversible mitotic entry, mainly by activating the phosphatase Cdc25 while suppressing the tyrosine kinase Wee1. Wee1 needs to be downregulated at the onset of mitosis to ensure rapid activation of Cdk1. In human somatic cells, one mechanism of suppressing Wee1 activity is mediated by ubiquitylation-dependent proteolysis through the Skp1/Cul1/F-box protein (SCF) ubiquitin E3 ligase complex. This mechanism is believed to be conserved from yeasts to humans. So far, the best-characterized human F-box proteins involved in recognition of Wee1 are β-TrCP (BTRCP) and Tome-1 (CDCA3). Although fission yeast Wee1 was the first identified member of its conserved kinase family, the F-box proteins involved in recognition and ubiquitylation of Wee1 have not been identified in this organism. In this study, our screen using Wee1- Renilla luciferase as the reporter revealed that two F-box proteins, Pof1 and Pof3, are required for downregulating Wee1 and are possibly responsible for recruiting Wee1 to SCF. Our genetic analyses supported a functional relevance between Pof1 and Pof3 and the rate of mitotic entry, and Pof3 might play a major role in this process. © 2018. Published by The Company of Biologists Ltd.
Spores of the mycorrhizal fungus Glomus mosseae host yeasts that solubilize phosphate and accumulate polyphosphates.

PubMed

Mirabal Alonso, Loreli; Kleiner, Diethelm; Ortega, Eduardo

2008-04-01

The present paper reports the presence of bacteria and yeasts tightly associated with spores of an isolate of Glomus mosseae. Healthy spores were surface disinfected by combining chloramine-T 5%, Tween-40, and cephalexin 2.5 g L(-1) (CTCf). Macerates of these spores were incubated on agar media, microorganisms were isolated, and two yeasts were characterized (EndoGm1, EndoGm11). Both yeasts were able to solubilize low-soluble P sources (Ca and Fe phosphates) and accumulate polyphosphates (polyPs). Sequence analysis of 18S ribosomal deoxyribonucleic acid showed that the yeasts belong to the genera Rhodotorula or Rhodosporidium (EndoGm1) and Cryptococcus (EndoGm11). Results from inoculation experiments showed an effect of the spore-associated yeasts on the root growth of rice, suggesting potential tripartite interactions with mycorrhizal fungi and plants.
Effects of a spoilage yeast from silage on in vitro ruminal fermentation.

PubMed

Santos, M C; Lock, A L; Mechor, G D; Kung, L

2015-04-01

Feeding silages with high concentrations of yeasts from aerobic spoilage is often implicated as a cause of poor animal performance on dairies. Our objective was to determine if a commonly found spoilage yeast, isolated from silage, had the potential to alter in vitro ruminal fermentations. A single colony of Issatchenkia orientalis, isolated from high-moisture corn, was grown in selective medium. The yeast culture was purified and added to in vitro culture tubes containing a total mixed ration (43% concentrate, 43% corn silage, 11% alfalfa haylage, and 3% alfalfa hay on a dry matter basis), buffer, and ruminal fluid to achieve added theoretical final concentrations of 0 (CTR), 4.40 (low yeast; LY), 6.40 (medium yeast; MY), and 8.40 (high yeast; HY) log10 cfu of yeast/mL of in vitro fluid. Seven separate tubes were prepared for each treatment and each time point and incubated for 12 and 24h at 39 °C. At the end of the incubation period, samples were analyzed for pH, yeast number, neutral detergent fiber (NDF) digestibility, volatile fatty acids (VFA), and fatty acids (FA). We found that total viable yeast counts decreased for all treatments in in vitro incubations but were still relatively high (5.3 log10 cfu of yeasts/mL) for HY after 24h of incubation. Addition of HY resulted in a lower pH and higher concentration of total VFA in culture fluid compared with other treatments. Moreover, additions of MY and HY decreased in vitro NDF digestibility compared with CTR, and the effect was greatest for HY. Overall, the biohydrogenation of dietary unsaturated FA was not altered by addition of I. orientalis and decreased over time with an increase in the accumulation of saturated FA, especially palmitic and stearic acids. We conclude that addition of I. orientalis, especially at high levels, has the potential to reduce in vitro NDF digestion and alter other aspects of ruminal fermentations. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All
Cloning and characterization of an inulinase gene from the marine yeast Candida membranifaciens subsp. flavinogenie W14-3 and its expression in Saccharomyces sp. W0 for ethanol production.

PubMed

Zhang, Lin-Lin; Tan, Mei-Juan; Liu, Guang-Lei; Chi, Zhe; Wang, Guang-Yuan; Chi, Zhen-Ming

2015-04-01

The INU1 gene encoding an exo-inulinase from the marine-derived yeast Candida membranifaciens subsp. flavinogenie W14-3 was cloned and characterized. It had an open reading frame of 1,536 bp long encoding an inulinase. The coding region of it was not interrupted by any intron. The cloned gene encoded 512 amino acid residues of a protein with a putative signal peptide of 23 amino acids and a calculated molecular mass of 57.8 kDa. The protein sequence deduced from the inulinase gene contained the inulinase consensus sequences (WMNDPNGL), (RDP), ECP FS and Q. The protein also had six conserved putative N-glycosylation sites. The deduced inulinase from the yeast strain W14-3 was found to be closely related to that from Candida kutaonensis sp. nov. KRF1, Kluyveromyces marxianus, and Cryptococcus aureus G7a. The inulinase gene with its signal peptide encoding sequence was subcloned into the pMIRSC11 expression vector and expressed in Saccharomyces sp. W0. The recombinant yeast strain W14-3-INU-112 obtained could produce 16.8 U/ml of inulinase activity and 12.5 % (v/v) ethanol from 250 g/l of inulin within 168 h. The monosaccharides were detected after the hydrolysis of inulin with the crude inulinase (the yeast culture). All the results indicated that the cloned gene and the recombinant yeast strain W14-3-INU-112 had potential applications in biotechnology.
History of genome editing in yeast.

PubMed

Fraczek, Marcin G; Naseeb, Samina; Delneri, Daniela

2018-05-01

For thousands of years humans have used the budding yeast Saccharomyces cerevisiae for the production of bread and alcohol; however, in the last 30-40 years our understanding of the yeast biology has dramatically increased, enabling us to modify its genome. Although S. cerevisiae has been the main focus of many research groups, other non-conventional yeasts have also been studied and exploited for biotechnological purposes. Our experiments and knowledge have evolved from recombination to high-throughput PCR-based transformations to highly accurate CRISPR methods in order to alter yeast traits for either research or industrial purposes. Since the release of the genome sequence of S. cerevisiae in 1996, the precise and targeted genome editing has increased significantly. In this 'Budding topic' we discuss the significant developments of genome editing in yeast, mainly focusing on Cre-loxP mediated recombination, delitto perfetto and CRISPR/Cas. © 2018 The Authors. Yeast published by John Wiley & Sons, Ltd.
PGASO: A synthetic biology tool for engineering a cellulolytic yeast

PubMed Central

2012-01-01

Background To achieve an economical cellulosic ethanol production, a host that can do both cellulosic saccharification and ethanol fermentation is desirable. However, to engineer a non-cellulolytic yeast to be such a host requires synthetic biology techniques to transform multiple enzyme genes into its genome. Results A technique, named Promoter-based Gene Assembly and Simultaneous Overexpression (PGASO), that employs overlapping oligonucleotides for recombinatorial assembly of gene cassettes with individual promoters, was developed. PGASO was applied to engineer Kluyveromycesmarxianus KY3, which is a thermo- and toxin-tolerant yeast. We obtained a recombinant strain, called KR5, that is capable of simultaneously expressing exoglucanase and endoglucanase (both of Trichodermareesei), a beta-glucosidase (from a cow rumen fungus), a neomycin phosphotransferase, and a green fluorescent protein. High transformation efficiency and accuracy were achieved as ~63% of the transformants was confirmed to be correct. KR5 can utilize beta-glycan, cellobiose or CMC as the sole carbon source for growth and can directly convert cellobiose and beta-glycan to ethanol. Conclusions This study provides the first example of multi-gene assembly in a single step in a yeast species other than Saccharomyces cerevisiae. We successfully engineered a yeast host with a five-gene cassette assembly and the new host is capable of co-expressing three types of cellulase genes. Our study shows that PGASO is an efficient tool for simultaneous expression of multiple enzymes in the kefir yeast KY3 and that KY3 can serve as a host for developing synthetic biology tools. PMID:22839502
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.
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
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. © 2014 The Authors. Yeast published by John Wiley & Sons, Ltd.
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
A Molecular Portrait of De Novo Genes in Yeasts.

PubMed

Vakirlis, Nikolaos; Hebert, Alex S; Opulente, Dana A; Achaz, Guillaume; Hittinger, Chris Todd; Fischer, Gilles; Coon, Joshua J; Lafontaine, Ingrid

2018-03-01

New genes, with novel protein functions, can evolve "from scratch" out of intergenic sequences. These de novo genes can integrate the cell's genetic network and drive important phenotypic innovations. Therefore, identifying de novo genes and understanding how the transition from noncoding to coding occurs are key problems in evolutionary biology. However, identifying de novo genes is a difficult task, hampered by the presence of remote homologs, fast evolving sequences and erroneously annotated protein coding genes. To overcome these limitations, we developed a procedure that handles the usual pitfalls in de novo gene identification and predicted the emergence of 703 de novo gene candidates in 15 yeast species from 2 genera whose phylogeny spans at least 100 million years of evolution. We validated 85 candidates by proteomic data, providing new translation evidence for 25 of them through mass spectrometry experiments. We also unambiguously identified the mutations that enabled the transition from noncoding to coding for 30 Saccharomyces de novo genes. We established that de novo gene origination is a widespread phenomenon in yeasts, only a few being ultimately maintained by selection. We also found that de novo genes preferentially emerge next to divergent promoters in GC-rich intergenic regions where the probability of finding a fortuitous and transcribed ORF is the highest. Finally, we found a more than 3-fold enrichment of de novo genes at recombination hot spots, which are GC-rich and nucleosome-free regions, suggesting that meiotic recombination contributes to de novo gene emergence in yeasts.
Between science and industry-applied yeast research.

PubMed

Korhola, Matti

2018-03-01

I was fortunate to enter yeast research at the Alko Research Laboratories with a strong tradition in yeast biochemistry and physiology studies. At the same time in the 1980s there was a fundamental or paradigm change in molecular biology research with discoveries in DNA sequencing and other analytical and physical techniques for studying macromolecules and cells. Since that time biotechnological research has expanded the traditional fermentation industries to efficient production of industrial and other enzymes and specialty chemicals. Our efforts were directed towards improving the industrial production organisms: minerals enriched yeasts (Se, Cr, Zn) and high glutathione content yeast, baker´s, distiller´s, sour dough and wine yeasts, and the fungal Trichoderma reesei platform for enzyme production. I am grateful for the trust of my colleagues in several leadership positions at the Alko Research Laboratories, Yeast Industry Platform and at the international yeast community.
Cyclin C influences the timing of mitosis in fission yeast.

PubMed

Banyai, Gabor; Szilagyi, Zsolt; Baraznenok, Vera; Khorosjutina, Olga; Gustafsson, Claes M

2017-07-01

The multiprotein Mediator complex is required for the regulated transcription of nearly all RNA polymerase II-dependent genes. Mediator contains the Cdk8 regulatory subcomplex, which directs periodic transcription and influences cell cycle progression in fission yeast. Here we investigate the role of CycC, the cognate cyclin partner of Cdk8, in cell cycle control. Previous reports suggested that CycC interacts with other cellular Cdks, but a fusion of CycC to Cdk8 reported here did not cause any obvious cell cycle phenotypes. We find that Cdk8 and CycC interactions are stabilized within the Mediator complex and the activity of Cdk8-CycC is regulated by other Mediator components. Analysis of a mutant yeast strain reveals that CycC, together with Cdk8, primarily affects M-phase progression but mutations that release Cdk8 from CycC control also affect timing of entry into S phase. © 2017 Banyai et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).
[Export of an invertase by yeast cells (Candida utilis)].

PubMed

Alekseeva, O V; Sabirzianova, T A; Celiakh, I O; Kalebina, T S; Kulaev, I S

2014-01-01

Export and accumulation of various forms of invertase (EC 3.2.1.26) in the cell wall and culture liquid of the yeast Candida utilis was investigated. It was found that the high-molecular-weight CW-form of invertase is present in the cell wall. This form is not exported into the culture liquid, and it is by a third more glycosylated than the previously described exported S-form. It was shown that one of the two liquid forms of invertase exported into the culture-the glycosylated S-form--is retained in the cell wall, while the other one--the nonglycosylated F-form--was not detected in the cell wall. Based on these results, as well as data on the distribution dynamics of the enzyme in the culture liquid and in the cell wall during different growth stages of a yeast culture, we suggested that the nonglycosylated form was exported into the culture liquid via the zone of abnormal cell wall permeability and the glycosylated forms of this enzyme (both exported and nonexported) did not use this pathway (the degree of N-glycosylation is an important factor determining the final localization of the enzyme).
The Effects of a Probiotic Yeast on the Bacterial Diversity and Population Structure in the Rumen of Cattle

PubMed Central

Pinloche, Eric; McEwan, Neil; Marden, Jean-Philippe; Bayourthe, Corinne; Auclair, Eric; Newbold, C. Jamie

2013-01-01

It has been suggested that the ability of live yeast to improve milk yield and weight gain in cattle is because the yeast stimulates bacterial activity within the rumen. However it remains unclear if this is a general stimulation of all species or a specific stimulation of certain species. Here we characterised the change in the bacterial population within the rumen of cattle fed supplemental live yeast. Three cannulated lactating cows received a daily ration (24 kg/d) of corn silage (61% of DM), concentrates (30% of DM), dehydrated alfalfa (9% of DM) and a minerals and vitamins mix (1% of DM). The effect of yeast (BIOSAF SC 47, Lesaffre Feed Additives, France; 0.5 or 5 g/d) was compared to a control (no additive) in a 3×3 Latin square design. The variation in the rumen bacterial community between treatments was assessed using Serial Analysis of V1 Ribosomal Sequence Tag (SARST-V1) and 454 pyrosequencing based on analysis of the 16S rRNA gene. Compared to the control diet supplementation of probiotic yeast maintained a healthy fermentation in the rumen of lactating cattle (higher VFA concentration [high yeast dose only], higher rumen pH, and lower Eh and lactate). These improvements were accompanied with a shift in the main fibrolytic group (Fibrobacter and Ruminococcus) and lactate utilising bacteria (Megasphaera and Selenomonas). In addition we have shown that the analysis of short V1 region of 16s rRNA gene (50–60 bp) could give as much phylogenetic information as a longer read (454 pyrosequencing of 250 bp). This study also highlights the difficulty of drawing conclusions on composition and diversity of complex microbiota because of the variation caused by the use of different methods (sequencing technology and/or analysis). PMID:23844101
Industrially Important Carbohydrate Degrading Enzymes from Yeasts: Pectinases, Chitinases, and β-1,3-Glucanases

NASA Astrophysics Data System (ADS)

Gummadi, Sathyanarayana N.; Kumar, D. Sunil; Dash, Swati S.; Sahu, Santosh Kumar

Polysaccharide degrading enzymes are hydrolytic enzymes, which have a lot of industrial potential and also play a crucial role in carbon recycling. Pectinases, chitinases and glucanases are the three major polysaccharide degrading enzymes found abundantly in nature and these enzymes are mainly produced by fungal strains. Production of these enzymes by yeasts is advantageous over fungi, because the former are easily amenable to genetic manipulations and time required for growth and production is less than that of the latter. Several yeasts belonging to Saccharomyces, Pichia, Rhodotorula and Cryptococcus produce extracellular pectinases, glucanases and chitinases. This chapter emphasizes on the biological significance of these enzymes, their production and their industrial applications.

Antibody biosensors for spoilage yeast detection based on impedance spectroscopy.

PubMed

Tubía, I; Paredes, J; Pérez-Lorenzo, E; Arana, S

2018-04-15

Brettanomyces is a yeast species responsible for wine and cider spoilage, producing volatile phenols that result in off-odors and loss of fruity sensorial qualities. Current commercial detection methods for these spoilage species are liable to frequent false positives, long culture times and fungal contamination. In this work, an interdigitated (IDE) biosensor was created to detect Brettanomyces using immunological reactions and impedance spectroscopy analysis. To promote efficient antibody immobilization on the electrodes' surface and to decrease non-specific adsorption, a Self-Assembled Monolayer (SAM) was developed. An impedance spectroscopy analysis, over four yeast strains, confirmed our device's increased efficacy. Compared to label-free sensors, antibody biosensors showed a higher relative impedance. The results also suggested that these biosensors could be a promising method to monitor some spoilage yeasts, offering an efficient alternative to the laborious and expensive traditional methods. Copyright © 2017 Elsevier B.V. All rights reserved.
Acetate but not propionate induces oxidative stress in bakers' yeast Saccharomyces cerevisiae.

PubMed

Semchyshyn, Halyna M; Abrat, Oleksandra B; Miedzobrodzki, Jacek; Inoue, Yoshiharu; Lushchak, Volodymyr I

2011-01-01

The influence of acetic and propionic acids on baker's yeast was investigated in order to expand our understanding of the effect of weak organic acid food preservatives on eukaryotic cells. Both acids decreased yeast survival in a concentration-dependent manner, but with different efficiencies. The acids inhibited the fluorescein efflux from yeast cells. The inhibition constant of fluorescein extrusion from cells treated with acetate was significantly lower in parental strain than in either PDR12 (ABC-transporter Pdr12p) or WAR1 (transcriptional factor of Pdr12p) defective mutants. The constants of inhibition by propionate were virtually the same in all strains used. Yeast exposure to acetate increased the level of oxidized proteins and the activity of antioxidant enzymes, while propionate did not change these parameters. This suggests that various mechanisms underlie the yeast toxicity by acetic and propionic acids. Our studies with mutant cells clearly indicated the involvement of Yap1p transcriptional regulator and de novo protein synthesis in superoxide dismutase up-regulation by acetate. The up-regulation of catalase was Yap1p independent. Yeast pre-incubation with low concentrations of H₂O₂ caused cellular cross-protection against high concentrations of acetate. The results are discussed from the point of view that acetate induces a prooxidant effect in vivo, whereas propionate does not.
Degradation of spent craft brewer's yeast by caprine rumen hyper ammonia-producing bacteria.

PubMed

Harlow, B E; Bryant, R W; Cohen, S D; O'Connell, S P; Flythe, M D

2016-10-01

Spent yeast from craft beers often includes more hops (Humulus lupulus L.) secondary metabolites than traditional recipes. These compounds include α- and β- acids, which are antimicrobial to the rumen hyper ammonia-producing bacteria (HAB) that are major contributors to amino acid degradation. The objective was to determine if the hops acids in spent craft brewer's yeast (CY; ~ 3·5 mg g(-1) hops acids) would protect it from degradation by caprine rumen bacteria and HAB when compared to a baker's yeast (BY; no hops acids). Cell suspensions were prepared by harvesting rumen fluid from fistulated goats, straining and differential centrifugation. The cells were re-suspended in media with BY or CY. After 24 h (39°C), HAB were enumerated and ammonia was measured. Fewer HAB and less ammonia was produced from CY than from BY. Pure culture experiments were conducted with Peptostreptococcus anaerobiusBG1 (caprine HAB). Ammonia production by BG1 from BY was greater than from CY. Ammonia production was greater when exogenous amino acids were included, but similar inhibition was observed in CY treatments. These results indicate that rumen micro-organisms deaminated the amino acids in CY to a lesser degree than BY. Spent brewer's yeast has long been included in ruminant diets as a protein supplement. However, modern craft beers often include more hops (Humulus lupulus L.) than traditional recipes. These compounds include α- and β- acids, which are antimicrobial to the rumen hyper ammonia-producing bacteria (HAB) that are major contributors to amino acid degradation. This study demonstrated that hops acids in spent craft brewer's yeast protected protein from destruction by HABin vitro. These results suggest that the spent yeast from craft breweries, a source of beneficial hops secondary metabolites, could have value as rumen-protected protein. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
Yeast-based biosensors: design and applications.

PubMed

Adeniran, Adebola; Sherer, Michael; Tyo, Keith E J

2015-02-01

Yeast-based biosensing (YBB) is an exciting research area, as many studies have demonstrated the use of yeasts to accurately detect specific molecules. Biosensors incorporating various yeasts have been reported to detect an incredibly large range of molecules including but not limited to odorants, metals, intracellular metabolites, carcinogens, lactate, alcohols, and sugars. We review the detection strategies available for different types of analytes, as well as the wide range of output methods that have been incorporated with yeast biosensors. We group biosensors into two categories: those that are dependent upon transcription of a gene to report the detection of a desired molecule and those that are independent of this reporting mechanism. Transcription-dependent biosensors frequently depend on heterologous expression of sensing elements from non-yeast organisms, a strategy that has greatly expanded the range of molecules available for detection by YBBs. Transcription-independent biosensors circumvent the problem of sensing difficult-to-detect analytes by instead relying on yeast metabolism to generate easily detected molecules when the analyte is present. The use of yeast as the sensing element in biosensors has proven to be successful and continues to hold great promise for a variety of applications. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.
Immune-modulatory effects of dietary Yeast Beta-1,3/1,6-D-glucan

PubMed Central

2014-01-01

Beta-glucans are a heterogeneous group of natural polysaccharides mostly investigated for their immunological effects. Due to the low systemic availability of oral preparations, it has been thought that only parenterally applied beta-glucans can modulate the immune system. However, several in vivo and in vitro investigations have revealed that orally applied beta-glucans also exert such effects. Various receptor interactions, explaining possible mode of actions, have been detected. The effects mainly depend on the source and structure of the beta-glucans. In the meantime, several human clinical trials with dietary insoluble yeast beta-glucans have been performed. The results confirm the previous findings of in vivo studies. The results of all studies taken together clearly indicate that oral intake of insoluble yeast beta-glucans is safe and has an immune strengthening effect. PMID:24774968
Overexpression of ACC gene from oleaginous yeast Lipomyces starkeyi enhanced the lipid accumulation in Saccharomyces cerevisiae with increased levels of glycerol 3-phosphate substrates.

PubMed

Wang, Jiancai; Xu, Ronghua; Wang, Ruling; Haque, Mohammad Enamul; Liu, Aizhong

2016-06-01

The conversion of acetyl-CoA to malonyl-CoA by acetyl-CoA carboxylase (ACC) is the rate-limiting step in fatty acid biosynthesis. In this study, a gene coding for ACC was isolated and characterized from an oleaginous yeast, Lipomyces starkeyi. Real-time quantitative PCR (qPCR) analysis of L. starkeyi acetyl-CoA carboxylase gene (LsACC1) showed that the expression levels were upregulated with the fast accumulation of lipids. The LsACC1 was co-overexpressed with the glycerol 3-phosphate dehydrogenase gene (GPD1), which regulates lipids biosynthesis by supplying another substrates glycerol 3-phosphate for storage lipid assembly, in the non-oleaginous yeast Saccharomyces cerevisiae. Further, the S. cerevisiae acetyl-CoA carboxylase (ScACC1) was transferred with GPD1 and its function was analyzed in comparison with LsACC1. The results showed that overexpressed LsACC1 and GPD1 resulted in a 63% increase in S. cerevisiae. This study gives new data in understanding of the molecular mechanisms underlying the regulation of fatty acids and lipid biosynthesis in yeasts.
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.
Yeasts of the soil – obscure but precious

PubMed Central

2018-01-01

Abstract Pioneering studies performed in the nineteenth century demonstrated that yeasts are present in below‐ground sources. Soils were regarded more as a reservoir for yeasts that reside in habitats above it. Later studies showed that yeast communities in soils are taxonomically diverse and different from those above‐ground. Soil yeasts possess extraordinary adaptations that allow them to survive in a wide range of environmental conditions. A few species are promising sources of yeast oils and have been used in agriculture as potential antagonists of soil‐borne plant pathogens or as plant growth promoters. Yeasts have been studied mainly in managed soils such as vineyards, orchards and agricultural fields, and to a lesser extent under forests and grasslands. Our knowledge of soil yeasts is further biased towards temperate and boreal forests, whereas data from Africa, the Americas and Asia are scarce. Although soil yeast communities are often species‐poor in a single sample, they are more diverse on the biotope level. Soil yeasts display pronounced endemism along with a surprisingly high proportion of currently unidentified species. However, like other soil inhabitants, yeasts are threatened by habitat alterations owing to anthropogenic activities such as agriculture, deforestation and urbanization. In view of the rapid decline of many natural habitats, the study of soil yeasts in undisturbed or low‐managed biotopes is extremely valuable. The purpose of this review is to encourage researchers, both biologists and soil scientists, to include soil yeasts in future studies. PMID:29365211
Distribution of dimorphic yeast species in commercial extra virgin olive oil.

PubMed

Zullo, B A; Cioccia, G; Ciafardini, G

2010-12-01

Recent microbiological research has demonstrated the presence of a rich microflora mainly composed of yeasts in the suspended fraction of freshly produced olive oil. Some of the yeasts are considered useful as they improve the organoleptic characteristics of the oil during preservation, whereas others are considered harmful as they can damage the quality of the oil through the hydrolysis of the triglycerides. However, some dimorphic species can also be found among the unwanted yeasts present in the oil, considered to be opportunistic pathogens to man as they have often been isolated from immunocompromised hospital patients. Present research demonstrates the presence of dimorphic yeast forms in 26% of the commercial extra virgin olive oil originating from different geographical areas, where the dimorphic yeasts are represented by 3-99.5% of the total yeasts. The classified isolates belonged to the opportunistic pathogen species Candida parapsilosis and Candida guilliermondii, while among the dimorphic yeasts considered not pathogenic to man, the Candida diddensiae species was highlighted for the first time in olive oil. The majority of the studied yeast strains resulted lipase positive, and can consequently negatively influence the oil quality through the hydrolysis of the triglycerides. Furthermore, all the strains showed a high level of affinity with some organic solvents and a differing production of biofilm in "vitro" corresponded to a greater or lesser hydrophobia of their cells. Laboratory trials indicated that the dimorphic yeasts studied are sensitive towards some components of the oil among which oleic acid, linoleic acid and triolein, whereas a less inhibiting effect was observed with tricaprilin or when the total polyphenols extracted from the oil were used. The observations carried out on a scanning electron microscope (SEM), demonstrated the production of long un-branched pseudohyphae in all the tested dimorphic yeasts when cultivated on nutrient
Yeast vitality during cider fermentation: assessment by energy metabolism.

PubMed

Dinsdale, M G; Lloyd, D; McIntyre, P; Jarvis, B

1999-03-15

In an apple juice-based medium, an ethanol-tolerant Australian wine-yeast used for cider manufacture produced more than 10% ethanol over a 5 week period. Growth of the inoculum (10(6) organisms ml(-1)) occurred to a population of 3.1 x 10(7) ml(-1) during the first few days; at the end of the fermentation only 5 x 10(5) yeasts ml(-1) could be recovered as colony-forming units on plates. Respiratory and fermentative activities were measured by mass spectrometric measurements (O2 consumption and CO2 and ethanol production) of washed yeast suspensions taken from the cider fermentation at intervals. Both endogenous and glucose-supported energy-yielding metabolism declined, especially during the first 20 days. Levels of adenine nucleotides also showed decreases after day 1, as did adenylate energy charge, although in a prolonged (16.5 week) fermentation the lowest value calculated was 0.55. AMP was released into the medium. 31P-NMR spectra showed that by comparison with aerobically grown yeast, that from the later stages of the cider fermentation showed little polyphosphate. However, as previously concluded from studies of 'acidification power' and fluorescent oxonol dye exclusion (Dinsdale et al., 1995), repitching of yeast indicated little loss of viability despite considerable loss of vitality.
Interactions between Drosophila and its natural yeast symbionts—Is Saccharomyces cerevisiae a good model for studying the fly-yeast relationship?

PubMed Central

Hoang, Don; Kopp, Artyom

2015-01-01

Yeasts play an important role in the biology of the fruit fly, Drosophila melanogaster. In addition to being a valuable source of nutrition, yeasts affect D. melanogaster behavior and interact with the host immune system. Most experiments investigating the role of yeasts in D. melanogaster biology use the baker’s yeast, Saccharomyces cerevisiae. However, S. cerevisiae is rarely found with natural populations of D. melanogaster or other Drosophila species. Moreover, the strain of S. cerevisiae used most often in D. melanogaster experiments is a commercially and industrially important strain that, to the best of our knowledge, was not isolated from flies. Since disrupting natural host–microbe interactions can have profound effects on host biology, the results from D. melanogaster–S. cerevisiae laboratory experiments may not be fully representative of host–microbe interactions in nature. In this study, we explore the D. melanogaster-yeast relationship using five different strains of yeast that were isolated from wild Drosophila populations. Ingested live yeasts have variable persistence in the D. melanogaster gastrointestinal tract. For example, Hanseniaspora occidentalis persists relative to S. cerevisiae, while Brettanomyces naardenensis is removed. Despite these differences in persistence relative to S. cerevisiae, we find that all yeasts decrease in total abundance over time. Reactive oxygen species (ROS) are an important component of the D. melanogaster anti-microbial response and can inhibit S. cerevisiae growth in the intestine. To determine if sensitivity to ROS explains the differences in yeast persistence, we measured yeast growth in the presence and absence of hydrogen peroxide. We find that B. naardenesis is completely inhibited by hydrogen peroxide, while H. occidentalis is not, which is consistent with yeast sensitivity to ROS affecting persistence within the D. melanogaster gastrointestinal tract. We also compared the feeding preference of D
Interactions between Drosophila and its natural yeast symbionts-Is Saccharomyces cerevisiae a good model for studying the fly-yeast relationship?

PubMed

Hoang, Don; Kopp, Artyom; Chandler, James Angus

2015-01-01

Yeasts play an important role in the biology of the fruit fly, Drosophila melanogaster. In addition to being a valuable source of nutrition, yeasts affect D. melanogaster behavior and interact with the host immune system. Most experiments investigating the role of yeasts in D. melanogaster biology use the baker's yeast, Saccharomyces cerevisiae. However, S. cerevisiae is rarely found with natural populations of D. melanogaster or other Drosophila species. Moreover, the strain of S. cerevisiae used most often in D. melanogaster experiments is a commercially and industrially important strain that, to the best of our knowledge, was not isolated from flies. Since disrupting natural host-microbe interactions can have profound effects on host biology, the results from D. melanogaster-S. cerevisiae laboratory experiments may not be fully representative of host-microbe interactions in nature. In this study, we explore the D. melanogaster-yeast relationship using five different strains of yeast that were isolated from wild Drosophila populations. Ingested live yeasts have variable persistence in the D. melanogaster gastrointestinal tract. For example, Hanseniaspora occidentalis persists relative to S. cerevisiae, while Brettanomyces naardenensis is removed. Despite these differences in persistence relative to S. cerevisiae, we find that all yeasts decrease in total abundance over time. Reactive oxygen species (ROS) are an important component of the D. melanogaster anti-microbial response and can inhibit S. cerevisiae growth in the intestine. To determine if sensitivity to ROS explains the differences in yeast persistence, we measured yeast growth in the presence and absence of hydrogen peroxide. We find that B. naardenesis is completely inhibited by hydrogen peroxide, while H. occidentalis is not, which is consistent with yeast sensitivity to ROS affecting persistence within the D. melanogaster gastrointestinal tract. We also compared the feeding preference of D
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.
Studying p53 family proteins in yeast: Induction of autophagic cell death and modulation by interactors and small molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leão, Mariana; Gomes, Sara; Bessa, Cláudia

In this work, the yeast Saccharomyces cerevisiae was used to individually study human p53, p63 (full length and truncated forms) and p73. Using this cell system, the effect of these proteins on cell proliferation and death, and the influence of MDM2 and MDMX on their activities were analyzed. When expressed in yeast, wild-type p53, TAp63, ΔNp63 and TAp73 induced growth inhibition associated with S-phase cell cycle arrest. This growth inhibition was accompanied by reactive oxygen species production and autophagic cell death. Furthermore, they stimulated rapamycin-induced autophagy. On the contrary, none of the tested p53 family members induced apoptosis either permore » se or after apoptotic stimuli. As previously reported for p53, also TAp63, ΔNp63 and TAp73 increased actin expression levels and its depolarization, suggesting that ACT1 is also a p63 and p73 putative yeast target gene. Additionally, MDM2 and MDMX inhibited the activity of all tested p53 family members in yeast, although the effect was weaker on TAp63. Moreover, Nutlin-3a and SJ-172550 were identified as potential inhibitors of the p73 interaction with MDM2 and MDMX, respectively. Altogether, the yeast-based assays herein developed can be envisaged as a simplified cell system to study the involvement of p53 family members in autophagy, the modulation of their activities by specific interactors (MDM2 and MDMX), and the potential of new small molecules to modulate these interactions. - Highlights: • p53, p63 and p73 are individually studied in the yeast S. cerevisiae. • p53 family members induce ROS production, cell cycle arrest and autophagy in yeast. • p53 family members increase actin depolarization and expression levels in yeast. • MDM2 and MDMX inhibit the activity of p53 family members in yeast. • Yeast can be a useful tool to study the biology and drugability of p53, p63 and p73.« less
Mechanisms by Which Different Functional States of Mitochondria Define Yeast Longevity

PubMed Central

Beach, Adam; Leonov, Anna; Arlia-Ciommo, Anthony; Svistkova, Veronika; Lutchman, Vicky; Titorenko, Vladimir I.

2015-01-01

Mitochondrial functionality is vital to organismal physiology. A body of evidence supports the notion that an age-related progressive decline in mitochondrial function is a hallmark of cellular and organismal aging in evolutionarily distant eukaryotes. Studies of the baker’s yeast Saccharomyces cerevisiae, a unicellular eukaryote, have led to discoveries of genes, signaling pathways and chemical compounds that modulate longevity-defining cellular processes in eukaryotic organisms across phyla. These studies have provided deep insights into mechanistic links that exist between different traits of mitochondrial functionality and cellular aging. The molecular mechanisms underlying the essential role of mitochondria as signaling organelles in yeast aging have begun to emerge. In this review, we discuss recent progress in understanding mechanisms by which different functional states of mitochondria define yeast longevity, outline the most important unanswered questions and suggest directions for future research. PMID:25768339
Evaluation of Different Yeast Species for Improving In vitro Fermentation of Cereal Straws

PubMed Central

Wang, Zuo; He, Zhixiong; Beauchemin, Karen A.; Tang, Shaoxun; Zhou, Chuanshe; Han, Xuefeng; Wang, Min; Kang, Jinhe; Odongo, Nicholas E.; Tan, Zhiliang

2016-01-01

Information on the effects of different yeast species on ruminal fermentation is limited. This experiment was conducted in a 3×4 factorial arrangement to explore and compare the effects of addition of three different live yeast species (Candida utilis 1314, Saccharomyces cerevisiae 1355, and Candida tropicalis 1254) at four doses (0, 0.25×107, 0.50×107, and 0.75×107 colony-forming unit [cfu]) on in vitro gas production kinetics, fiber degradation, methane production and ruminal fermentation characteristics of maize stover, and rice straw by mixed rumen microorganisms in dairy cows. The maximum gas production (Vf), dry matter disappearance (IVDMD), neutral detergent fiber disappearance (IVNDFD), and methane production in C. utilis group were less (p<0.01) than other two live yeast supplemented groups. The inclusion of S. cerevisiae reduced (p<0.01) the concentrations of ammonia nitrogen (NH3-N), isobutyrate, and isovalerate compared to the other two yeast groups. C. tropicalis addition generally enhanced (p<0.05) IVDMD and IVNDFD. The NH3-N concentration and CH4 production were increased (p<0.05) by the addition of S. cerevisiae and C. tropicalis compared with the control. Supplementation of three yeast species decreased (p<0.05) or numerically decreased the ratio of acetate to propionate. The current results indicate that C. tropicalis is more preferred as yeast culture supplements, and its optimal dose should be 0.25×107 cfu/500 mg substrates in vitro. PMID:26732448
The effect of yeast (Saccharomyces cerevisiae) on nutrient intake, digestibility and finishing performance of lambs fed a diet based on dried molasses sugar beet-pulp.

PubMed

Payandeh, S; Kafilzadeh, F

2007-12-15

This experiment was conducted to determine the effect of yeast (Saccharomyces cerevisiae, SC47) on finishing performance, digestibility, some blood metabolites and carcass characteristics of male lambs fed a diet based on dried Molasses Sugar Beet-Pulp (MSBP). Eighteen Sanjabi male lambs (20.95 +/- 2.7 kg initial body weight and 3 month of age) were used in a completely randomized design. Animals were assigned to one of the two dietary treatments (with or without yeast). Digestibility and nitrogen balance experiment was carried out using six mature rams on finishing diet with and without yeast. Serum metabolites were determined in samples taken from lambs at the end of finishing period. Dry matter digestibility of finishing diet was significantly increased by yeast addition. However, yeast did not have any significant effect on apparent digestibility of OM, NDF, CP and energy. Nitrogen retention was also not affected by yeast addition. Yeast resulted in a significant increase in the average daily gain, dry matter and organic matter intake. However, feed conversion ratio was not significantly affected by addition of yeast. The concentration of the serum metabolites including glucose, urea, cholesterol, sodium, potassium, calcium, phosphorous and cratinine were not affected significantly by yeast supplementation, but triglyceride concentrations increased significantly when yeast was fed. Addition of yeast to the diet did not have any significant effect on the carcass characteristics. Results of this study suggest that feeding saccharomyces cerevisiae with a diet based on MSBP can improve the performance of fattening lambs without any change in carcass characteristics or cuts.
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
Quantitative 3D imaging of yeast by hard X-ray tomography.

PubMed

Zheng, Ting; Li, Wenjie; Guan, Yong; Song, Xiangxia; Xiong, Ying; Liu, Gang; Tian, Yangchao

2012-05-01

Full-field hard X-ray tomography could be used to obtain three-dimensional (3D) nanoscale structures of biological samples. The image of the fission yeast, Schizosaccharomyces pombe, was clearly visualized based on Zernike phase contrast imaging technique and heavy metal staining method at a spatial resolution better than 50 nm at the energy of 8 keV. The distributions and shapes of the organelles during the cell cycle were clearly visualized and two types of organelle were distinguished. The results for cells during various phases were compared and the ratios of organelle volume to cell volume can be analyzed quantitatively. It showed that the ratios remained constant between growth and division phase and increased strongly in stationary phase, following the shape and size of two types of organelles changes. Our results demonstrated that hard X-ray microscopy was a complementary method for imaging and revealing structural information for biological samples. Copyright © 2011 Wiley Periodicals, Inc.
Sfp1 and Rtg3 reciprocally modulate carbon source‐conditional stress adaptation in the pathogenic yeast Candida albicans

PubMed Central

Kastora, Stavroula L.; Herrero‐de‐Dios, Carmen; Avelar, Gabriela M.; Munro, Carol A.

2017-01-01

Summary The pathogenicity of the clinically important yeast, Candida albicans, is dependent on robust responses to host‐imposed stresses. These stress responses have generally been dissected in vitro at 30°C on artificial growth media that do not mimic host niches. Yet host inputs, such as changes in carbon source or temperature, are known to affect C. albicans stress adaptation. Therefore, we performed screens to identify novel regulators that promote stress resistance during growth on a physiologically relevant carboxylic acid and at elevated temperatures. These screens revealed that, under these ‘non‐standard’ growth conditions, numerous uncharacterised regulators are required for stress resistance in addition to the classical Hog1, Cap1 and Cta4 stress pathways. In particular, two transcription factors (Sfp1 and Rtg3) promote stress resistance in a reciprocal, carbon source‐conditional manner. SFP1 is induced in stressed glucose‐grown cells, whereas RTG3 is upregulated in stressed lactate‐grown cells. Rtg3 and Sfp1 regulate the expression of key stress genes such as CTA4, CAP1 and HOG1 in a carbon source‐dependent manner. These mechanisms underlie the stress sensitivity of C. albicans sfp1 cells during growth on glucose, and rtg3 cells on lactate. The data suggest that C. albicans exploits environmentally contingent regulatory mechanisms to retain stress resistance during host colonisation. PMID:28574606

Isolation and Identification of the Indigenous Yeast Population during Spontaneous Fermentation of Isabella (Vitis labrusca L.) Grape Must.

PubMed

Raymond Eder, María L; Reynoso, Cristina; Lauret, Santiago C; Rosa, Alberto L

2017-01-01

Grape must harbors a complex community of yeast species responsible for spontaneous alcoholic fermentation. Although there are detailed studies on the microbiota of Vitis vinifera L. grapes, less is known about the diversity and behavior of yeast communities present on fermenting grape must from other species of Vitis . In this work, we used a culture-dependent method to study the identity and dynamics of the indigenous yeast population present during the spontaneous fermentation of Isabella ( Vitis labrusca L.) grape must. Alcoholic fermentation was conducted using standard enological practices, and the associated non- Saccharomyces and S. cerevisiae yeast community was analyzed using selective growth media and 5.8-ITS DNA sequencing. Candida californica, Candida hellenica, Starmerella bacillaris (synonym Candida zemplinina ), Hanseniaspora uvarum , and Hanseniaspora vineae were the main non- Saccharomyces species identified on Isabella fermenting must. Issatchenkia hanoiensis , a yeast species rarely found on Vitis vinifera L. grapes, was also recognized on Isabella grape must. Candida azymoides, Candida californica and Pichia cecembensis , identified in this work on Isabella fermenting must, have not previously been found on Vitis vinifera L. grape must. Interestingly, C. azymoides, I. hanoiensis and P. cecembensis have recently been isolated from the surface of Vitis labrusca L. grapes from vineyards in the Azores archipelago, suggesting that specific Vitis -yeast species associations are formed independently of geographic origin. We suggest that C. azymoides, C. californica , and P. cecembensis are yeast species preferentially associated with Vitis labrusca L. grapes. Specific biological interactions between grapevines and yeast species may underlie the assembly of differential Vitis -microbial communities.
Isolation and Identification of the Indigenous Yeast Population during Spontaneous Fermentation of Isabella (Vitis labrusca L.) Grape Must

PubMed Central

Raymond Eder, María L.; Reynoso, Cristina; Lauret, Santiago C.; Rosa, Alberto L.

2017-01-01

Grape must harbors a complex community of yeast species responsible for spontaneous alcoholic fermentation. Although there are detailed studies on the microbiota of Vitis vinifera L. grapes, less is known about the diversity and behavior of yeast communities present on fermenting grape must from other species of Vitis. In this work, we used a culture-dependent method to study the identity and dynamics of the indigenous yeast population present during the spontaneous fermentation of Isabella (Vitis labrusca L.) grape must. Alcoholic fermentation was conducted using standard enological practices, and the associated non-Saccharomyces and S. cerevisiae yeast community was analyzed using selective growth media and 5.8-ITS DNA sequencing. Candida californica, Candida hellenica, Starmerella bacillaris (synonym Candida zemplinina), Hanseniaspora uvarum, and Hanseniaspora vineae were the main non-Saccharomyces species identified on Isabella fermenting must. Issatchenkia hanoiensis, a yeast species rarely found on Vitis vinifera L. grapes, was also recognized on Isabella grape must. Candida azymoides, Candida californica and Pichia cecembensis, identified in this work on Isabella fermenting must, have not previously been found on Vitis vinifera L. grape must. Interestingly, C. azymoides, I. hanoiensis and P. cecembensis have recently been isolated from the surface of Vitis labrusca L. grapes from vineyards in the Azores archipelago, suggesting that specific Vitis-yeast species associations are formed independently of geographic origin. We suggest that C. azymoides, C. californica, and P. cecembensis are yeast species preferentially associated with Vitis labrusca L. grapes. Specific biological interactions between grapevines and yeast species may underlie the assembly of differential Vitis-microbial communities. PMID:28424672
Effects of dietary live and heat-inactive baker's yeast on growth, gut health, and disease resistance of Nile tilapia under high rearing density.

PubMed

Ran, Chao; Huang, Lu; Hu, Jun; Tacon, Philippe; He, Suxu; Li, Zhimin; Wang, Yibing; Liu, Zhi; Xu, Li; Yang, Yalin; Zhou, Zhigang

2016-09-01

In this study, the effects of baker's yeast as probiotics was evaluated in Nile tilapia reared at high density. Juvenile tilapia were distributed to tanks at high density (436 fish/m(3)) and fed with basal diet (CK) or diets supplemented with live (LY) or heat-inactivated yeast (HIY). Another group of fish reared at low density (218 fish/m(3)) and fed with basal diet was also included (LowCK). After 8 weeks of feeding, growth, feed utilization, gut microvilli morphology, digestive enzymes, and expressions of hsp70 and inflammation-related cytokines in the intestine were assessed. Intestinal microbiota was investigated using 16S rRNA gene pyrosequencing. Fish were challenged with Aeromonas hydrophila to evaluate disease resistance. High rearing density significantly decreased the growth, feed utilization, microvilli length, and disease resistance of fish (CK versus LowCK). Moreover, the intestinal hsp70 expression was increased in fish reared at high density, supporting a stress condition. Compared to CK group, supplementation of live yeast significantly increased gut microvilli length and trypsin activity, decreased intestinal hsp70 expression, and enhanced resistance of fish against A. hydrophila (reflected by reduced intestinal alkaline phosphatase activity 24 h post infection). The gut microbiota was not markedly influenced by either rearing density or yeast supplementation. Heat-inactivated yeast (HIY) didn't display the beneficial effects observed in LY except an increase in gut trypsin activity, suggesting the importance of yeast viability and thus secretory metabolites of yeast. In conclusion, live baker's yeast may alleviate the negative effects induced by crowding stress, and has the potential to be used as probiotics for tilapia reared at high density. Copyright © 2016 Elsevier Ltd. All rights reserved.
Optimization of carbon and nitrogen medium components for biomass production using non-Saccharomyces wine yeasts.

PubMed

Schnierda, T; Bauer, F F; Divol, B; van Rensburg, E; Görgens, J F

2014-05-01

The impact of different nitrogen and carbon sources on biomass production of the non-Saccharomyces wine yeast species Lachancea thermotolerans, Metschnikowia pulcherrima and Issatchenkia orientalis was assessed. Using a molasses-based medium, yeast extract and corn steep liquor as well as ammonium sulphate and di-ammonium phosphate (DAP) as nitrogen sources were compared in shake-flask cultures. A medium with 20 g l⁻¹ sugar (diluted molasses) and 500 mg l⁻¹ total yeast assimilable nitrogen, from yeast extract, gave the highest biomass concentrations and yields. Invertase pretreatment was required for cultures of M. pulcherrima and I. orientalis, and respective biomass yields of 0.7 and 0.8 g g⁻¹ were achieved in aerobic bioreactor cultures. The absence of ethanol production suggested Crabtree-negative behaviour by these yeasts, whereas Crabtree-positive behaviour by L. thermotolerans resulted in ethanol and biomass concentrations of 5.5 and 11.1 g l⁻¹, respectively. Recent studies demonstrate that non-Saccharomyces yeasts confer positive attributes to the final composition of wine. However, optimal process conditions for their biomass production have not been described, thereby limiting commercial application. In this study, industrial media and methods of yeast cultivation were investigated to develop protocols for biomass production of non-Saccharomyces yeast starter cultures for the wine industry. © 2014 The Society for Applied Microbiology.
Study on the effects of near-future ocean acidification on marine yeasts: a microcosm approach

NASA Astrophysics Data System (ADS)

Krause, Evamaria; Wichels, Antje; Erler, René; Gerdts, Gunnar

2013-12-01

Marine yeasts play an important role in biodegradation and nutrient cycling and are often associated with marine flora and fauna. They show maximum growth at pH levels lower than present-day seawater pH. Thus, contrary to many other marine organisms, they may actually profit from ocean acidification. Hence, we conducted a microcosm study, incubating natural seawater from the North Sea at present-day pH (8.10) and two near-future pH levels (7.81 and 7.67). Yeasts were isolated from the initial seawater sample and after 2 and 4 weeks of incubation. Isolates were classified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and representative isolates were identified by partial sequencing of the large subunit rRNA gene. From the initial seawater sample, we predominantly isolated a yeast-like filamentous fungus related to Aureobasidium pullulans, Cryptococcus sp., Candida sake, and various cold-adapted yeasts. After incubation, we found more different yeast species at near-future pH levels than at present-day pH. Yeasts reacting to low pH were related to Leucosporidium scottii, Rhodotorula mucilaginosa, Cryptococcus sp., and Debaryomyces hansenii. Our results suggest that these yeasts will benefit from seawater pH reductions and give a first indication that the importance of yeasts will increase in a more acidic ocean.
Genomics and the making of yeast biodiversity.

PubMed

Hittinger, Chris Todd; Rokas, Antonis; Bai, Feng-Yan; Boekhout, Teun; Gonçalves, Paula; Jeffries, Thomas W; Kominek, Jacek; Lachance, Marc-André; Libkind, Diego; Rosa, Carlos A; Sampaio, José Paulo; Kurtzman, Cletus P

2015-12-01

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 cerevisiae; the common human commensal and opportunistic pathogen, Candida albicans; and over 1000 other known species (with more continuing to be discovered). Yeasts are found in every biome and continent and are more genetically diverse than angiosperms or chordates. Ease of culture, simple life cycles, and small genomes (∼10-20Mbp) have made yeasts exceptional models for molecular genetics, biotechnology, and evolutionary genomics. Here we discuss recent developments in understanding the genomic underpinnings of the making of yeast biodiversity, comparing and contrasting natural and human-associated evolutionary processes. Only a tiny fraction of yeast biodiversity and metabolic capabilities has been tapped by industry and science. Expanding the taxonomic breadth of deep genomic investigations will further illuminate how genome function evolves to encode their diverse metabolisms and ecologies. Copyright © 2015 Elsevier Ltd. All rights reserved.
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.
Drug Uptake, Lipid Rafts, and Vesicle Trafficking Modulate Resistance to an Anticancer Lysophosphatidylcholine Analogue in Yeast*

PubMed Central

Cuesta-Marbán, Álvaro; Botet, Javier; Czyz, Ola; Cacharro, Luis M.; Gajate, Consuelo; Hornillos, Valentín; Delgado, Javier; Zhang, Hui; Amat-Guerri, Francisco; Acuña, A. Ulises; McMaster, Christopher R.; Revuelta, José Luis; Zaremberg, Vanina; Mollinedo, Faustino

2013-01-01

The ether-phospholipid edelfosine, a prototype antitumor lipid (ATL), kills yeast cells and selectively kills several cancer cell types. To gain insight into its mechanism of action, we performed chemogenomic screens in the Saccharomyces cerevisiae gene-deletion strain collection, identifying edelfosine-resistant mutants. LEM3, AGP2, and DOC1 genes were required for drug uptake. Edelfosine displaced the essential proton pump Pma1p from rafts, inducing its internalization into the vacuole. Additional ATLs, including miltefosine and perifosine, also displaced Pma1p from rafts to the vacuole, suggesting that this process is a major hallmark of ATL cytotoxicity in yeast. Radioactive and synthetic fluorescent edelfosine analogues accumulated in yeast plasma membrane rafts and subsequently the endoplasmic reticulum. Although both edelfosine and Pma1p were initially located at membrane rafts, internalization of the drug toward endoplasmic reticulum and Pma1p to the vacuole followed different routes. Drug internalization was not dependent on endocytosis and was not critical for yeast cytotoxicity. However, mutants affecting endocytosis, vesicle sorting, or trafficking to the vacuole, including the retromer and ESCRT complexes, prevented Pma1p internalization and were edelfosine-resistant. Our data suggest that edelfosine-induced cytotoxicity involves raft reorganization and retromer- and ESCRT-mediated vesicular transport and degradation of essential raft proteins leading to cell death. Cytotoxicity of ATLs is mainly dependent on the changes they induce in plasma membrane raft-located proteins that lead to their internalization and subsequent degradation. Edelfosine toxicity can be circumvented by inactivating genes that then result in the recycling of internalized cell-surface proteins back to the plasma membrane. PMID:23335509
Panax Ginseng in combination with brewers' yeast (Gerivet) as a stimulant for geriatric dogs: a controlled-randomized blinded study.

PubMed

Hielm-Björkman, A; Reunanen, V; Meri, P; Tulamo, R-M

2007-08-01

The study was performed on two groups of dogs, one (n = 41) given Ginseng (Panax Ginseng) together with brewers' yeast (Saccharomyces cerevisae) and the other (n = 39) given only brewers' yeast (control group, but not a true placebo), for 8 weeks. Using a questionnaire and three visual analogue scales, the blinded owners evaluated the dogs before the trial, weekly for the 8 weeks of the trial and twice, at 12th and 16th weeks, after the trial (follow-up). At 8th, 12th and 16th weeks the owners also answered questions concerning what treatment their dogs likely had been getting, willingness to continue medication and the dogs' general status. The changes from baseline to the end of the treatment period in the variable scores were calculated for each dog and used in statistics. Panax Ginseng plus yeast significantly improved all evaluated variables within the group. Four of the seven primary (mentally) outcome measures were significant when comparing the changes in the Ginseng group with the control group, and six of the seven were significant when compared to an external group. As the secondary (physical) outcome measures were significantly better in both the Ginseng and the control group compared to the external group, it indicates that brewers' yeast is the ingredient that has impact on physical performance. No significant changes in blood- or urine analyses and no side effects were seen.
Impact of pitching rate on yeast fermentation performance and beer flavour.

PubMed

Verbelen, P J; Dekoninck, T M L; Saerens, S M G; Van Mulders, S E; Thevelein, J M; Delvaux, F R

2009-02-01

The volumetric productivity of the beer fermentation process can be increased by using a higher pitching rate (i.e. higher inoculum size). However, the impact of the pitching rate on crucial fermentation and beer quality parameters has never been assessed systematically. In this study, five pitching rates were applied to lab-scale fermentations to investigate its impact on the yeast physiology and beer quality. The fermentation rate increased significantly and the net yeast growth was lowered with increasing pitching rate, without affecting significantly the viability and the vitality of the yeast population. The build-up of unsaturated fatty acids in the initial phase of the fermentation was repressed when higher yeast concentrations were pitched. The expression levels of the genes HSP104 and HSP12 and the concentration of trehalose were higher with increased pitching rates, suggesting a moderate exposure to stress in case of higher cell concentrations. The influence of pitching rate on aroma compound production was rather limited, with the exception of total diacetyl levels, which strongly increased with the pitching rate. These results demonstrate that most aspects of the yeast physiology and flavour balance are not significantly or negatively affected when the pitching rate is changed. However, further research is needed to fully optimise the conditions for brewing beer with high cell density populations.
Binding of Soluble Yeast β-Glucan to Human Neutrophils and Monocytes is Complement-Dependent

PubMed Central

Bose, Nandita; Chan, Anissa S. H.; Guerrero, Faimola; Maristany, Carolyn M.; Qiu, Xiaohong; Walsh, Richard M.; Ertelt, Kathleen E.; Jonas, Adria Bykowski; Gorden, Keith B.; Dudney, Christine M.; Wurst, Lindsay R.; Danielson, Michael E.; Elmasry, Natalie; Magee, Andrew S.; Patchen, Myra L.; Vasilakos, John P.

2013-01-01

The immunomodulatory properties of yeast β-1,3/1,6 glucans are mediated through their ability to be recognized by human innate immune cells. While several studies have investigated binding of opsonized and unopsonized particulate β-glucans to human immune cells mainly via complement receptor 3 (CR3) or Dectin-1, few have focused on understanding the binding characteristics of soluble β-glucans. Using a well-characterized, pharmaceutical-grade, soluble yeast β-glucan, this study evaluated and characterized the binding of soluble β-glucan to human neutrophils and monocytes. The results demonstrated that soluble β-glucan bound to both human neutrophils and monocytes in a concentration-dependent and receptor-specific manner. Antibodies blocking the CD11b and CD18 chains of CR3 significantly inhibited binding to both cell types, establishing CR3 as the key receptor recognizing the soluble β-glucan in these cells. Binding of soluble β-glucan to human neutrophils and monocytes required serum and was also dependent on incubation time and temperature, strongly suggesting that binding was complement-mediated. Indeed, binding was reduced in heat-inactivated serum, or in serum treated with methylamine or in serum reacted with the C3-specific inhibitor compstatin. Opsonization of soluble β-glucan was demonstrated by detection of iC3b, the complement opsonin on β-glucan-bound cells, as well as by the direct binding of iC3b to β-glucan in the absence of cells. Binding of β-glucan to cells was partially inhibited by blockade of the alternative pathway of complement, suggesting that the C3 activation amplification step mediated by this pathway also contributed to binding. PMID:23964276
[Groups and sources of yeasts in house dust].

PubMed

Glushakova, A M; Zheltikova, T M; Chernov, I Iu

2004-01-01

House dust contains bacteria, mycelial fungi, microarthropods, and yeasts. The house dust samples collected in 25 apartments in Moscow and the Moscow region were found to contain yeasts belonging to the genera Candida, Cryptococcus, Debaryomyces, Rhodotorula, Sporobolomyces, and Trichosporon. The most frequently encountered microorganisms were typical epiphytic yeasts, such as Cryptococcus diffluens and Rhodotorula mucilaginosa, which are capable of long-term preservation in an inactive state. The direct source of epiphytic yeasts occurring in the house dust might be the indoor plants, which were contaminated with these yeasts, albeit to a lesser degree than outdoor plants. Along with the typical epiphytic yeasts, the house dust contained the opportunistic yeast pathogens Candida catenulata, C. guillermondii, C. haemulonii, C. rugosa, and C. tropicalis, which are known as the causal agents of candidiasis. We failed to reveal any correlation between the abundance of particular yeast species in the house dust, residential characteristics, and the atopic dermatitis of the inhabitants.
Nectar Yeasts in the Tall Larkspur Delphinium barbeyi (Ranunculaceae) and Effects on Components of Pollinator Foraging Behavior

PubMed Central

Schaeffer, Robert N.; Phillips, Cody R.; Duryea, M. Catherine; Andicoechea, Jonathan; Irwin, Rebecca E.

2014-01-01

Microorganisms frequently colonize the nectar of angiosperm species. Though capable of altering a suite of traits important for pollinator attraction, few studies exist that test the degree to which they mediate pollinator foraging behavior. The objective of our study was to fill this gap by assessing the abundance and diversity of yeasts associated with the perennial larkspur Delphinium barbeyi (Ranunculaceae) and testing whether their presence affected components of pollinator foraging behavior. Yeasts frequently colonized D. barbeyi nectar, populating 54–77% of flowers examined depending on site. Though common, the yeast community was species-poor, represented by a single species, Metschnikowia reukaufii. Female-phase flowers of D. barbeyi were more likely to have higher densities of yeasts in comparison to male-phase flowers. Pollinators were likely vectors of yeasts, as virgin (unvisited) flowers rarely contained yeasts compared to flowers open to pollinator visitation, which were frequently colonized. Finally, pollinators responded positively to the presence of yeasts. Bombus foragers both visited and probed more flowers inoculated with yeasts in comparison to uninoculated controls. Taken together, our results suggest that variation in the occurrence and density of nectar-inhabiting yeasts have the potential to alter components of pollinator foraging behavior linked to pollen transfer and plant fitness. PMID:25272164
Inactivation of bacterial quorum sensing signals N-acyl homoserine lactones is widespread in yeasts.

PubMed

Leguina, Ana Carolina Del V; Nieto, Carolina; Pajot, Hipólito M; Bertini, Elisa V; Mac Cormack, Walter; Castellanos de Figueroa, Lucía I; Nieto-Peñalver, Carlos G

2018-01-01

The inactivation of quorum sensing signals, a phenomenon known as quorum quenching, has been described in diverse microorganisms, though it remains almost unexplored in yeasts. Beyond the well-known properties of these microorganisms for the industry or as eukaryotic models, the role of yeasts in soil or in the inner tissues of a plant is largely unknown. In this report, the wider survey of quorum quenching activities in yeasts isolated from Antarctic soil and the inner tissues of sugarcane, a tropical crop, is presented. Results show that, independently of their niche, quorum quenching activities are broadly present in unicellular fungi. Although yeasts showing a broad range of quorum quenching activity are present in the two niches, at the same time specific AHL inactivation profiles can also be found. Furthermore, yeasts from both sampling sites show quorum quenching activities compatible with lactonase-like and acylase-like inactivations of AHLs. Interestingly, the characterization of Rhodotorula mucilaginosa 7Apo1 showed that the presence of a particular AHL does not interfere with the quenching of a second molecule. Evidence suggests that yeasts could play a role in the modulation of the quorum sensing activity of bacteria. The relationship among phylogeny, sampling sites and yeast quorum quenching activities of the isolates is analyzed. Copyright © 2017 British Mycological Society. Published by Elsevier Ltd. All rights reserved.
Yeast identification: reassessment of assimilation tests as sole universal identifiers.

PubMed

Spencer, J; Rawling, S; Stratford, M; Steels, H; Novodvorska, M; Archer, D B; Chandra, S

2011-11-01

To assess whether assimilation tests in isolation remain a valid method of identification of yeasts, when applied to a wide range of environmental and spoilage isolates. Seventy-one yeast strains were isolated from a soft drinks factory. These were identified using assimilation tests and by D1/D2 rDNA sequencing. When compared to sequencing, assimilation test identifications (MicroLog™) were 18·3% correct, a further 14·1% correct within the genus and 67·6% were incorrectly identified. The majority of the latter could be attributed to the rise in newly reported yeast species. Assimilation tests alone are unreliable as a universal means of yeast identification, because of numerous new species, variability of strains and increasing coincidence of assimilation profiles. Assimilation tests still have a useful role in the identification of common species, such as the majority of clinical isolates. It is probable, based on these results, that many yeast identifications reported in older literature are incorrect. This emphasizes the crucial need for accurate identification in present and future publications. © 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.
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.
Genomics and the making of yeast biodiversity

USDA-ARS?s Scientific Manuscript database

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 ...
Yeast-yeast interactions revealed by aromatic profile analysis of Sauvignon Blanc wine fermented by single or co-culture of non-Saccharomyces and Saccharomyces yeasts.

PubMed

Sadoudi, Mohand; Tourdot-Maréchal, Raphaëlle; Rousseaux, Sandrine; Steyer, Damien; Gallardo-Chacón, Joan-Josep; Ballester, Jordi; Vichi, Stefania; Guérin-Schneider, Rémi; Caixach, Josep; Alexandre, Hervé

2012-12-01

There has been increasing interest in the use of selected non-Saccharomyces yeasts in co-culture with Saccharomyces cerevisiae. The main reason is that the multistarter fermentation process is thought to simulate indigenous fermentation, thus increasing wine aroma complexity while avoiding the risks linked to natural fermentation. However, multistarter fermentation is characterised by complex and largely unknown interactions between yeasts. Consequently the resulting wine quality is rather unpredictable. In order to better understand the interactions that take place between non-Saccharomyces and Saccharomyces yeasts during alcoholic fermentation, we analysed the volatile profiles of several mono-culture and co-cultures. Candida zemplinina, Torulaspora delbrueckii and Metschnikowia pulcherrima were used to conduct fermentations either in mono-culture or in co-culture with S. cerevisiae. Up to 48 volatile compounds belonging to different chemical families were quantified. For the first time, we show that C. zemplinina is a strong producer of terpenes and lactones. We demonstrate by means of multivariate analysis that different interactions exist between the co-cultures studied. We observed a synergistic effect on aromatic compound production when M. pulcherrima was in co-culture with S. cerevisiae. However a negative interaction was observed between C. zemplinina and S. cerevisiae, which resulted in a decrease in terpene and lactone content. These interactions are independent of biomass production. The aromatic profiles of T. delbrueckii and S. cerevisiae in mono-culture and in co-culture are very close, and are biomass-dependent, reflecting a neutral interaction. This study reveals that a whole family of compounds could be altered by such interactions. These results suggest that the entire metabolic pathway is affected by these interactions. Copyright © 2012 Elsevier Ltd. All rights reserved.
In vitro ability of beer fermentation residue and yeast-based products to bind aflatoxin B1.

PubMed

Bovo, Fernanda; Franco, Larissa Tuanny; Rosim, Roice Eliana; Barbalho, Ricardo; de Oliveira, Carlos Augusto Fernandes

2015-06-01

This study aimed to verify the in vitro ability of beer fermentation residue (BFR) containing Saccharomyces cerevisiae cells and five commercial products that differed in the viability and integrity of S. cerevisiae cells to remove aflatoxin B1 (AFB1) from a citrate-phosphate buffer solution (CPBS). BFR was collected at a microbrewery and prepared by drying and milling. The commercial yeast-based products were as follows: inactive intact yeast cells from beer alcoholic fermentation, inactive intact yeast cells from sugarcane alcoholic fermentation, hydrolyzed yeast cells, yeast cell walls and active yeast cells. Adsorption assays were performed in CPBS spiked with 1.0 μg AFB1/mL at pH 3.0 and 6.0 for a contact time of 60 min at room temperature. Analysis of AFB1 in the samples was performed by high performance liquid chromatography. AFB1 adsorption by the products ranged from 45.5% to 69.4% at pH 3.0 and from 24.0% to 63.8% at pH 6.0. The higher percentages (p < 0.05) of AFB1 binding at both pH values were achieved with products containing hydrolyzed yeast cells or yeast cell walls rather than intact cells. The AFB1 binding percentages of BFR were 55.0 ± 5.0% at pH 3.0 and 49.2 ± 4.5% at pH 6.0, which was not significantly different (p > 0.05) from commercial products containing inactive intact yeast cells. The results of this trial indicate that the yeast-based products tested, especially the BFR, have potential applications in animal feeds as a suitable biological method for reducing the adverse effects of aflatoxins.
In vitro ability of beer fermentation residue and yeast-based products to bind aflatoxin B1

PubMed Central

Bovo, Fernanda; Franco, Larissa Tuanny; Rosim, Roice Eliana; Barbalho, Ricardo; de Oliveira, Carlos Augusto Fernandes

2015-01-01

This study aimed to verify the in vitro ability of beer fermentation residue (BFR) containing Saccharomyces cerevisiae cells and five commercial products that differed in the viability and integrity of S. cerevisiae cells to remove aflatoxin B1 (AFB1) from a citrate-phosphate buffer solution (CPBS). BFR was collected at a microbrewery and prepared by drying and milling. The commercial yeast-based products were as follows: inactive intact yeast cells from beer alcoholic fermentation, inactive intact yeast cells from sugarcane alcoholic fermentation, hydrolyzed yeast cells, yeast cell walls and active yeast cells. Adsorption assays were performed in CPBS spiked with 1.0 μg AFB1/mL at pH 3.0 and 6.0 for a contact time of 60 min at room temperature. Analysis of AFB1 in the samples was performed by high performance liquid chromatography. AFB1 adsorption by the products ranged from 45.5% to 69.4% at pH 3.0 and from 24.0% to 63.8% at pH 6.0. The higher percentages (p < 0.05) of AFB1 binding at both pH values were achieved with products containing hydrolyzed yeast cells or yeast cell walls rather than intact cells. The AFB1 binding percentages of BFR were 55.0 ± 5.0% at pH 3.0 and 49.2 ± 4.5% at pH 6.0, which was not significantly different (p > 0.05) from commercial products containing inactive intact yeast cells. The results of this trial indicate that the yeast-based products tested, especially the BFR, have potential applications in animal feeds as a suitable biological method for reducing the adverse effects of aflatoxins. PMID:26273277

Screening and characterizing of xylanolytic and xylose-fermenting yeasts isolated from the wood-feeding termite, Reticulitermes chinensis

PubMed Central

Xie, Rongrong; Zhou, Feng; Huang, Miao

2017-01-01

The effective fermentation of xylose remains an intractable challenge in bioethanol industry. The relevant xylanase enzyme is also in a high demand from industry for several biotechnological applications that inevitably in recent times led to many efforts for screening some novel microorganisms for better xylanase production and fermentation performance. Recently, it seems that wood-feeding termites can truly be considered as highly efficient natural bioreactors. The highly specialized gut systems of such insects are not yet fully realized, particularly, in xylose fermentation and xylanase production to advance industrial bioethanol technology as well as industrial applications of xylanases. A total of 92 strains from 18 yeast species were successfully isolated and identified from the gut of wood-feeding termite, Reticulitermes chinensis. Of these yeasts and strains, seven were identified for new species: Candida gotoi, Candida pseudorhagii, Hamamotoa lignophila, Meyerozyma guilliermondii, Sugiyamaella sp.1, Sugiyamaella sp. 2, and Sugiyamaella sp.3. Based on the phylogenetic and phenotypic characterization, the type strain of C. pseudorhagii sp. nov., which was originally designated strain SSA-1542T, was the most frequently occurred yeast from termite gut samples, showed the highly xylanolytic activity as well as D-xylose fermentation. The highest xylanase activity was recorded as 1.73 and 0.98 U/mL with xylan or D-xylose substrate, respectively, from SSA-1542T. Among xylanase-producing yeasts, four novel species were identified as D-xylose-fermenting yeasts, where the yeast, C. pseudorhagii SSA-1542T, showed the highest ethanol yield (0.31 g/g), ethanol productivity (0.31 g/L·h), and its fermentation efficiency (60.7%) in 48 h. Clearly, the symbiotic yeasts isolated from termite guts have demonstrated a competitive capability to produce xylanase and ferment xylose, suggesting that the wood-feeding termite gut is a promising reservoir for novel xylanases
Local climatic conditions constrain soil yeast diversity patterns in Mediterranean forests, woodlands and scrub biome.

PubMed

Yurkov, Andrey M; Röhl, Oliver; Pontes, Ana; Carvalho, Cláudia; Maldonado, Cristina; Sampaio, José Paulo

2016-02-01

Soil yeasts represent a poorly known fraction of the soil microbiome due to limited ecological surveys. Here, we provide the first comprehensive inventory of cultivable soil yeasts in a Mediterranean ecosystem, which is the leading biodiversity hotspot for vascular plants and vertebrates in Europe. We isolated and identified soil yeasts from forested sites of Serra da Arrábida Natural Park (Portugal), representing the Mediterranean forests, woodlands and scrub biome. Both cultivation experiments and the subsequent species richness estimations suggest the highest species richness values reported to date, resulting in a total of 57 and 80 yeast taxa, respectively. These values far exceed those reported for other forest soils in Europe. Furthermore, we assessed the response of yeast diversity to microclimatic environmental factors in biotopes composed of the same plant species but showing a gradual change from humid broadleaf forests to dry maquis. We observed that forest properties constrained by precipitation level had strong impact on yeast diversity and on community structure and lower precipitation resulted in an increased number of rare species and decreased evenness values. In conclusion, the structure of soil yeast communities mirrors the environmental factors that affect aboveground phytocenoses, aboveground biomass and plant projective cover. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Outlining the influence of non-conventional yeasts in wine ageing over lees.

PubMed

Belda, Ignacio; Navascués, Eva; Marquina, Domingo; Santos, Antonio; Calderón, Fernando; Benito, Santiago

2016-07-01

During the last decade, the use of innovative yeast cultures of both Saccharomyces cerevisiae and non-Saccharomyces yeasts as alternative tools to manage the winemaking process have turned the oenology industry. Although the contribution of different yeast species to wine quality during fermentation is increasingly understood, information about their role in wine ageing over lees is really scarce. This work aims to analyse the incidence of three non-Saccharomyces yeast species of oenological interest (Torulaspora delbrueckii, Lachancea thermotolerans and Metschnikowia pulcherrima) and of a commercial mannoprotein-overproducer S. cerevisiae strain compared with a conventional industrial yeast strain during wine ageing over lees. To evaluate their incidence in mouthfeel properties of wine after 4 months of ageing, the mannoprotein content of wines was evaluated, together with other wine analytic parameters, such as colour and aroma, biogenic amines and amino acids profile. Some differences among the studied parameters were observed during the study, especially regarding the mannoprotein concentration of wines. Our results suggest that the use of T. delbrueckii lees in wine ageing is a useful tool for the improvement of overall wine quality by notably increasing mannoproteins, reaching values higher than obtained using a S. cerevisiae overproducer strain. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.
Opposing roles for DNA structure-specific proteins Rad1, Msh2, Msh3, and Sgs1 in yeast gene targeting.

PubMed

Langston, Lance D; Symington, Lorraine S

2005-06-15

Targeted gene replacement (TGR) in yeast and mammalian cells is initiated by the two free ends of the linear targeting molecule, which invade their respective homologous sequences in the chromosome, leading to replacement of the targeted locus with a selectable gene from the targeting DNA. To study the postinvasion steps in recombination, we examined the effects of DNA structure-specific proteins on TGR frequency and heteroduplex DNA formation. In strains deleted of RAD1, MSH2, or MSH3, we find that the frequency of TGR is reduced and the mechanism of TGR is altered while the reverse is true for deletion of SGS1, suggesting that Rad1 and Msh2:Msh3 facilitate TGR while Sgs1 opposes it. The altered mechanism of TGR in the absence of Msh2:Msh3 and Rad1 reveals a separate role for these proteins in suppressing an alternate gene replacement pathway in which incorporation of both homology regions from a single strand of targeting DNA into heteroduplex with the targeted locus creates a mismatch between the selectable gene on the targeting DNA and the targeted gene in the chromosome.
Simultaneous accumulation of proline and trehalose in industrial baker's yeast enhances fermentation ability in frozen dough.

PubMed

Sasano, Yu; Haitani, Yutaka; Hashida, Keisuke; Ohtsu, Iwao; Shima, Jun; Takagi, Hiroshi

2012-05-01

Freeze tolerance is a necessary characteristic for industrial baker's yeast because frozen-dough baking is one of the key technologies for supplying oven-fresh bakery products to consumers. Both proline and trehalose are known to function as cryoprotectants in yeast cells. In order to enhance the freeze tolerance of yeast cells, we constructed a self-cloning diploid baker's yeast strain with simultaneous accumulation of proline, by expressing the PRO1-I150T allele, encoding the proline-feedback inhibition-less sensitive γ-glutamyl kinase, and trehalose, by disrupting the NTH1 gene, encoding neutral trehalase. The resultant strain retained higher tolerance to oxidative and freezing stresses than did the single proline- or trehalose-accumulating strain. Interestingly, our results suggest that proline and trehalose protect yeast cells from short-term and long-term freezing, respectively. Simultaneous accumulation of proline and trehalose in industrial baker's yeast also enhanced the fermentation ability in the frozen dough compared with the single accumulation of proline or trehalose. These results indicate that baker's yeast that accumulates both proline and trehalose is applicable for frozen-dough baking. Copyright © 2012 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.
Evidence for propagation of cold-adapted yeast in an ice core from a Siberian Altai glacier

NASA Astrophysics Data System (ADS)

Uetake, Jun; Kohshima, Shiro; Nakazawa, Fumio; Takeuchi, Nozomu; Fujita, Koji; Miyake, Takayuki; Narita, Hideki; Aizen, Vladimir; Nakawo, Masayoshi

2011-03-01

Cold environments, including glacier ice and snow, are known habitats for cold-adapted microorganisms. We investigated the potential for cold-adapted yeast to have propagated in the snow of the high-altitude Belukha glacier. We detected the presence of highly concentrated yeast (over 104 cells mL-1) in samples of both an ice core and firn snow. Increasing yeast cell concentrations in the same snow layer from July 2002 to July 2003 suggests that the yeast cells propagated in the glacier snow. A cold-adapted Rhodotorula sp. was isolated from the snow layer and found to be related to psychrophilic yeast previously found in other glacial environments (based on the D1/D2 26S rRNA domains). 26S rRNA clonal analysis directly amplified from meltwater within the ice core also revealed the presence of genus Rhodotorula. Analyses of the ice core showed that all peaks in yeast concentration corresponded to the peaks in indices of surface melting. These results support the hypothesis that occasional surface melting in an accumulation area is one of the major factors influencing cold-adapted yeast propagation.
Stability of patulin to sulfur dioxide and to yeast fermentation.

PubMed

Burroughs, L F

1977-01-01

The affinity of patulin for sulfur dioxide (SO2) is much less than was previously reported and is of little significance at the SO2 concentrations (below 200 ppm) used in the processing of apple juice and cider. However, at concentrations of 2000 ppm SO2 and 15 ppm patulin, combination was 90% complete in 2 days. Removal of SO2 liberated only part of the patulin, which suggests that 2 mechanisms are involved: one reversible (opening the hemiacetal ring) and one irreversible (SO2 addition at the double bond). Test with 2 yeasts used in English commercial cider making confirmed that patulin is effectively removed during yeast fermentation.
Nectar bacteria, but not yeast, weaken a plant-pollinator mutualism.

PubMed

Vannette, Rachel L; Gauthier, Marie-Pierre L; Fukami, Tadashi

2013-02-07

Mutualistic interactions are often subject to exploitation by species that are not directly involved in the mutualism. Understanding which organisms act as such 'third-party' species and how they do so is a major challenge in the current study of mutualistic interactions. Here, we show that even species that appear ecologically similar can have contrasting effects as third-party species. We experimentally compared the effects of nectar-inhabiting bacteria and yeasts on the strength of a mutualism between a hummingbird-pollinated shrub, Mimulus aurantiacus, and its pollinators. We found that the common bacterium Gluconobacter sp., but not the common yeast Metschnikowia reukaufii, reduced pollination success, seed set and nectar consumption by pollinators, thereby weakening the plant-pollinator mutualism. We also found that the bacteria reduced nectar pH and total sugar concentration more greatly than the yeasts did and that the bacteria decreased glucose concentration and increased fructose concentration whereas the yeasts affected neither. These distinct changes to nectar chemistry may underlie the microbes' contrasting effects on the mutualism. Our results suggest that it is necessary to understand the determinants of microbial species composition in nectar and their differential modification of floral rewards to explain the mutual benefits that plants and pollinators gain from each other.
Nectar bacteria, but not yeast, weaken a plant–pollinator mutualism

PubMed Central

Vannette, Rachel L.; Gauthier, Marie-Pierre L.; Fukami, Tadashi

2013-01-01

Mutualistic interactions are often subject to exploitation by species that are not directly involved in the mutualism. Understanding which organisms act as such ‘third-party’ species and how they do so is a major challenge in the current study of mutualistic interactions. Here, we show that even species that appear ecologically similar can have contrasting effects as third-party species. We experimentally compared the effects of nectar-inhabiting bacteria and yeasts on the strength of a mutualism between a hummingbird-pollinated shrub, Mimulus aurantiacus, and its pollinators. We found that the common bacterium Gluconobacter sp., but not the common yeast Metschnikowia reukaufii, reduced pollination success, seed set and nectar consumption by pollinators, thereby weakening the plant–pollinator mutualism. We also found that the bacteria reduced nectar pH and total sugar concentration more greatly than the yeasts did and that the bacteria decreased glucose concentration and increased fructose concentration whereas the yeasts affected neither. These distinct changes to nectar chemistry may underlie the microbes' contrasting effects on the mutualism. Our results suggest that it is necessary to understand the determinants of microbial species composition in nectar and their differential modification of floral rewards to explain the mutual benefits that plants and pollinators gain from each other. PMID:23222453
Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption.

PubMed

Luo, Ying; Wang, Jianguo; Liu, Bin; Wang, Zhouli; Yuan, Yahong; Yue, Tianli

2015-01-01

The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry.
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
The rate of metabolism as a factor determining longevity of the Saccharomyces cerevisiae yeast.

PubMed

Molon, Mateusz; Szajwaj, Monika; Tchorzewski, Marek; Skoczowski, Andrzej; Niewiadomska, Ewa; Zadrag-Tecza, Renata

2016-02-01

Despite many controversies, the yeast Saccharomyces cerevisiae continues to be used as a model organism for the study of aging. Numerous theories and hypotheses have been created for several decades, yet basic mechanisms of aging have remained unclear. Therefore, the principal aim of this work is to propose a possible mechanism leading to increased longevity in yeast. In this paper, we suggest for the first time that there is a link between decreased metabolic activity, fertility and longevity expressed as time of life in yeast. Determination of reproductive potential and total lifespan with the use of fob1Δ and sfp1Δ mutants allows us to compare the "longevity" presented as the number of produced daughters with the longevity expressed as the time of life. The results of analyses presented in this paper suggest the need for a change in the definition of longevity of yeast by taking into consideration the time parameter. The mutants that have been described as "long-lived" in the literature, such as the fob1Δ mutant, have an increased reproductive potential but live no longer than their standard counterparts. On the other hand, the sfp1Δ mutant and the wild-type strain produce a similar number of daughter cells, but the former lives much longer. Our results demonstrate a correlation between the decreased efficiency of the translational apparatus and the longevity of the sfp1Δ mutant. We suggest that a possible factor regulating the lifespan is the rate of cell metabolism. To measure the basic metabolism of the yeast cells, we used the isothermal microcalorimetry method. In the case of sfp1Δ, the flow of energy, ATP concentration, polysome profile and translational fitness are significantly lower in comparison with the wild-type strain and the fob1Δ mutant.
Enhanced leavening properties of baker's yeast by reducing sucrase activity in sweet dough.

PubMed

Zhang, Cui-Ying; Lin, Xue; Feng, Bing; Liu, Xiao-Er; Bai, Xiao-Wen; Xu, Jia; Pi, Li; Xiao, Dong-Guang

2016-07-01

Leavening ability in sweet dough is required for the commercial applications of baker's yeast. This property depends on many factors, such as glycolytic activity, sucrase activity, and osmotolerance. This study explored the importance of sucrase level on the leavening ability of baker's yeast in sweet dough. Furthermore, the baker's yeast strains with varying sucrase activities were constructed by deleting SUC2, which encodes sucrase or replacing the SUC2 promoter with the VPS8/TEF1 promoter. The results verify that the sucrase activity negatively affects the leavening ability of baker's yeast strains under high-sucrose conditions. Based on a certain level of osmotolerance, sucrase level plays a significant role in the fermentation performance of baker's yeast, and appropriate sucrase activity is an important determinant for the leavening property of baker's yeast in sweet dough. Therefore, modification on sucrase activity is an effective method for improving the leavening properties of baker's yeast in sweet dough. This finding provides guidance for the breeding of industrial baker's yeast strains for sweet dough leavening. The transformants BS1 with deleted SUC2 genetic background provided decreased sucrase activity (a decrease of 39.3 %) and exhibited enhanced leavening property (an increase of 12.4 %). Such a strain could be useful for industrial applications.
Genetics of Yeasts

NASA Astrophysics Data System (ADS)

Querol, Amparo; Fernández-Espinar, M. Teresa; Belloch, Carmela

The use of yeasts in biotechnology processes dates back to ancient days. Before 7000 BC, beer was produced in Sumeria. Wine was made in Assyria in 3500 BC, and ancient Rome had over 250 bakeries, which were making leavened bread by 100 BC. And milk has been made into Kefyr and Koumiss in Asia for many centuries (Demain, Phaff, & Kurtzman, 1999). However, the importance of yeast in the food and beverage industries was only realized about 1860, when their role in food manufacturing became evident.
Schizosaccharomyces pombe Noc3 Is Essential for Ribosome Biogenesis and Cell Division but Not DNA Replication▿

PubMed Central

Houchens, Christopher R.; Perreault, Audrey; Bachand, François; Kelly, Thomas J.

2008-01-01

The initiation of eukaryotic DNA replication is preceded by the assembly of prereplication complexes (pre-RCs) at chromosomal origins of DNA replication. Pre-RC assembly requires the essential DNA replication proteins ORC, Cdc6, and Cdt1 to load the MCM DNA helicase onto chromatin. Saccharomyces cerevisiae Noc3 (ScNoc3), an evolutionarily conserved protein originally implicated in 60S ribosomal subunit trafficking, has been proposed to be an essential regulator of DNA replication that plays a direct role during pre-RC formation in budding yeast. We have cloned Schizosaccharomyces pombe noc3+ (Spnoc3+), the S. pombe homolog of the budding yeast ScNOC3 gene, and functionally characterized the requirement for the SpNoc3 protein during ribosome biogenesis, cell cycle progression, and DNA replication in fission yeast. We showed that fission yeast SpNoc3 is a functional homolog of budding yeast ScNoc3 that is essential for cell viability and ribosome biogenesis. We also showed that SpNoc3 is required for the normal completion of cell division in fission yeast. However, in contrast to the proposal that ScNoc3 plays an essential role during DNA replication in budding yeast, we demonstrated that fission yeast cells do enter and complete S phase in the absence of SpNoc3, suggesting that SpNoc3 is not essential for DNA replication in fission yeast. PMID:18606828
Alcohol Dehydrogenase Activities of Wine Yeasts in Relation to Higher Alcohol Formation

PubMed Central

Singh, Rajendra; Kunkee, Ralph E.

1976-01-01

Alcohol dehydrogenase activities were examined in cell-free extracts of 10 representative wine yeast strains having various productivities of higher alcohols (fusel oil). The amount of fusel alcohols (n-propanol, isobutanol, active pentanol, and isopentanol) produced by the different yeasts and the specific alcohol dehydrogenase activities with the corresponding alcohols as substrates were found to be significantly related. No such relationship was found for ethanol. The amounts of higher alcohols formed during vinification could be predicted from the specific activities of the alcohol dehydrogenases with high accuracy. The results suggest a close relationship between the control of the activities of alcohol dehydrogenase and the formation of fusel oil alcohols. Also, new procedures for the prediction of higher alcohol formation during alcoholic beverage fermentation are suggested. PMID:16345179
Yeasts in sustainable bioethanol production: A review.

PubMed

Mohd Azhar, Siti Hajar; Abdulla, Rahmath; Jambo, Siti Azmah; Marbawi, Hartinie; Gansau, Jualang Azlan; Mohd Faik, Ainol Azifa; Rodrigues, Kenneth Francis

2017-07-01

Bioethanol has been identified as the mostly used biofuel worldwide since it significantly contributes to the reduction of crude oil consumption and environmental pollution. It can be produced from various types of feedstocks such as sucrose, starch, lignocellulosic and algal biomass through fermentation process by microorganisms. Compared to other types of microoganisms, yeasts especially Saccharomyces cerevisiae is the common microbes employed in ethanol production due to its high ethanol productivity, high ethanol tolerance and ability of fermenting wide range of sugars. However, there are some challenges in yeast fermentation which inhibit ethanol production such as high temperature, high ethanol concentration and the ability to ferment pentose sugars. Various types of yeast strains have been used in fermentation for ethanol production including hybrid, recombinant and wild-type yeasts. Yeasts can directly ferment simple sugars into ethanol while other type of feedstocks must be converted to fermentable sugars before it can be fermented to ethanol. The common processes involves in ethanol production are pretreatment, hydrolysis and fermentation. Production of bioethanol during fermentation depends on several factors such as temperature, sugar concentration, pH, fermentation time, agitation rate, and inoculum size. The efficiency and productivity of ethanol can be enhanced by immobilizing the yeast cells. This review highlights the different types of yeast strains, fermentation process, factors affecting bioethanol production and immobilization of yeasts for better bioethanol production.
Yeast succession in the Amazon fruit Parahancornia amapa as resource partitioning among Drosophila spp.

PubMed Central

Morais, P B; Martins, M B; Klaczko, L B; Mendonça-Hagler, L C; Hagler, A N

1995-01-01

The succession of yeasts colonizing the fallen ripe amapa fruit, from Parahancornia amapa, was examined. The occupation of the substrate depended on both the competitive interactions of yeast species, such as the production of killer toxins, and the selective dispersion by the drosophilid guild of the amapa fruit. The yeast community associated with this Amazon fruit differed from those isolated from other fruits in the same forest. The physiological profile of these yeasts was mostly restricted to the assimilation of a few simple carbon sources, mainly L-sorbose, D-glycerol, DL-lactate, cellobiose, and salicin. Common fruit-associated yeasts of the genera Kloeckera and Hanseniaspora, Candida guilliermondii, and Candida krusei colonized fruits during the first three days after the fruit fell. These yeasts were dispersed and served as food for the invader Drosophila malerkotliana. The resident flies of the Drosophila willistoni group fed selectively on patches of yeasts colonizing fruits 3 to 10 days after the fruit fell. The killer toxin-producing yeasts Pichia kluyveri var. kluyveri and Candida fructus were probably involved in the exclusion of some species during the intermediate stages of fruit deterioration. An increase in pH, inhibiting toxin activity and the depletion of simple sugars, may have promoted an increase in yeast diversity in the later stages of decomposition. The yeast succession provided a patchy environment for the drosophilids sharing this ephemeral substrate. PMID:8534092
Yeast hnRNP-related proteins contribute to the maintenance of telomeres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee-Soety, Julia Y., E-mail: jlee04@sju.edu; Jones, Jennifer; MacGibeny, Margaret A.

Highlights: Black-Right-Pointing-Pointer Yeast hnRNP-related proteins are able to prevent faster senescence in telomerase-null cells. Black-Right-Pointing-Pointer The conserved RRMs in Npl3 are important for telomere maintenance. Black-Right-Pointing-Pointer Human hnRNP A1 is unable to complement the lack of NPL3 in yeast. Black-Right-Pointing-Pointer Npl3 and Cbc2 may work as telomere capping proteins. -- Abstract: Telomeres protect the ends of linear chromosomes, which if eroded to a critical length can become uncapped and lead to replicative senescence. Telomerase maintains telomere length in some cells, but inappropriate expression facilitates the immortality of cancer cells. Recently, proteins involved in RNA processing and ribosome assembly, such asmore » hnRNP (heterogeneous nuclear ribonucleoprotein) A1, have been found to participate in telomere maintenance in mammals. The Saccharomyces cerevisiae protein Npl3 shares significant amino acid sequence similarities with hnRNP A1. We found that deleting NPL3 accelerated the senescence of telomerase null cells. The highly conserved RNA recognition motifs (RRM) in Npl3 appear to be important for preventing faster senescence. Npl3 preferentially binds telomere sequences in vitro, suggesting that Npl3 may affect telomeres directly. Despite similarities between the two proteins, human hnRNP A1 is unable to complement the lack of Npl3 to rescue accelerated senescence in tlc1 npl3 cells. Deletion of CBC2, which encodes another hnRNP-related protein that associates with Npl3, also accelerates senescence. Potential mechanisms by which hnRNP-related proteins maintain telomeres are discussed.« less
[Yeast diversity in Bulnesia retama and Larrea divaricata canopies and associated soils].

PubMed

Toro, M E; Oro, N P; Vega, A D; Maturano, Y P; Nally, M C; Fernandez, E; Pucheta, E; Vázquez, F

2005-01-01

Bush like vegetation dominates arid environments, and there is nutrients accumulation under shrub canopies and relatively unfertile soils between vegetal patches areas. Plants are one of the most common habitats for yeasts. There are many reports about yeasts inhabiting different plant components. Nevertheless, there are no reports about yeasts associated with Zygophyllaceae, an important shrub family of the Argentinean Province of Monte. The objective of this work was to analyzed yeast biodiversity of Bulnesia retama and Larrea divaricata canopies and associated soils, at Medanos Grandes of Caucete, San Juan, Argentina. Eighty seven (87) isolated yeasts were identified. From B. retama canopy and associated soil was observed a larger taxonomical diversity respect to L. divaricata. Nine (9) and ten (10) species were isolated from canopy and associated soil of B. retama, respectively. From L. divaricata canopy were 4 species and 3 species from its associated soil isolated. Identified genera were: Candida, Debaryomyces, Dekkera, Saccharomyces, Torulaspora, Sporidiobolus and Pichia. Fourteen (14) species were found at all microenvironments.

Getting Down to Business.

ERIC Educational Resources Information Center

Dessoff, Alan L.

1995-01-01

This article presents five basic guidelines for initiating a successful alumni merchandising program: (1) shop around for the best vendor; (2) decide what to sell; (3) manage merchandise properly; (4) watch out for risky business; and (5) get what you pay for. (MDM)
A serendipitous discovery that in situ proteolysis is essential for the crystallization of yeast CPSF-100 (Ydh1p)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mandel, Corey R.; Gebauer, Damara; Zhang, Hailong

2006-10-01

Proteolysis in situ by a protease secreted by a contaminating fungus is essential for the crystallization of yeast CPSF-100. The cleavage and polyadenylation specificity factor (CPSF) complex is required for the cleavage and polyadenylation of the 3′-end of messenger RNA precursors in eukaryotes. During structural studies of the 100 kDa subunit (CPSF-100, Ydh1p) of the yeast CPSF complex, it was serendipitously discovered that a solution that is infected by a fungus (subsequently identified as Penicillium) is crucial for the crystallization of this protein. Further analyses suggest that the protein has undergone partial proteolysis during crystallization, resulting in the deletion ofmore » an internal segment of about 200 highly charged and hydrophilic residues, very likely catalyzed by a protease secreted by the fungus. With the removal of this segment, yeast CPSF-100 (Ydh1p) has greatly reduced solubility and can be crystallized in the presence of a minute amount of precipitant.« less
Differential regulation of mitochondrial pyruvate carrier genes modulates respiratory capacity and stress tolerance in yeast.

PubMed

Timón-Gómez, Alba; Proft, Markus; Pascual-Ahuir, Amparo

2013-01-01

Mpc proteins are highly conserved from yeast to humans and are necessary for the uptake of pyruvate at the inner mitochondrial membrane, which is used for leucine and valine biosynthesis and as a fuel for respiration. Our analysis of the yeast MPC gene family suggests that amino acid biosynthesis, respiration rate and oxidative stress tolerance are regulated by changes in the Mpc protein composition of the mitochondria. Mpc2 and Mpc3 are highly similar but functionally different: Mpc2 is most abundant under fermentative non stress conditions and important for amino acid biosynthesis, while Mpc3 is the most abundant family member upon salt stress or when high respiration rates are required. Accordingly, expression of the MPC3 gene is highly activated upon NaCl stress or during the transition from fermentation to respiration, both types of regulation depend on the Hog1 MAP kinase. Overexpression experiments show that gain of Mpc2 function leads to a severe respiration defect and ROS accumulation, while Mpc3 stimulates respiration and enhances tolerance to oxidative stress. Our results identify the regulated mitochondrial pyruvate uptake as an important determinant of respiration rate and stress resistance.
Yeast peroxisomal multifunctional enzyme: (3R)-hydroxyacyl-CoA dehydrogenase domains A and B are required for optimal growth on oleic acid.

PubMed

Qin, Y M; Marttila, M S; Haapalainen, A M; Siivari, K M; Glumoff, T; Hiltunen, J K

1999-10-01

The yeast peroxisomal (3R)-hydroxyacyl-CoA dehydrogenase/2-enoyl-CoA hydratase 2 (multifunctional enzyme type 2; MFE-2) has two N-terminal domains belonging to the short chain alcohol dehydrogenase/reductase superfamily. To investigate the physiological roles of these domains, here called A and B, Saccharomyces cerevisiae fox-2 cells (devoid of Sc MFE-2) were taken as a model system. Gly(16) and Gly(329) of the S. cerevisiae A and B domains, corresponding to Gly(16), which is mutated in the human MFE-2 deficiency, were mutated to serine and cloned into the yeast expression plasmid pYE352. In oleic acid medium, fox-2 cells transformed with pYE352:: ScMFE-2(aDelta) and pYE352::ScMFE-2(bDelta) grew slower than cells transformed with pYE352::ScMFE-2, whereas cells transformed with pYE352::ScMFE-2(aDeltabDelta) failed to grow. Candida tropicalis MFE-2 with a deleted hydratase 2 domain (Ct MFE- 2(h2Delta)) and mutational variants of the A and B domains (Ct MFE- 2(h2DeltaaDelta), Ct MFE- 2(h2DeltabDelta), and Ct MFE- 2(h2DeltaaDeltabDelta)) were overexpressed and characterized. All proteins were dimers with similar secondary structure elements. Both wild type domains were enzymatically active, with the B domain showing the highest activity with short chain and the A domain with medium and long chain (3R)-hydroxyacyl-CoA substrates. The data show that the dehydrogenase domains of yeast MFE-2 have different substrate specificities required to allow the yeast to propagate optimally on fatty acids as the carbon source.
Reconstitution of the yeast RNA polymerase III transcription system with all recombinant factors.

PubMed

Ducrot, Cécile; Lefebvre, Olivier; Landrieux, Emilie; Guirouilh-Barbat, Josée; Sentenac, André; Acker, Joel

2006-04-28

Transcription factor TFIIIC is a multisubunit complex required for promoter recognition and transcriptional activation of class III genes. We describe here the reconstitution of complete recombinant yeast TFIIIC and the molecular characterization of its two DNA-binding domains, tauA and tauB, using the baculovirus expression system. The B block-binding module, rtauB, was reconstituted with rtau138, rtau91, and rtau60 subunits. rtau131, rtau95, and rtau55 formed also a stable complex, rtauA, that displayed nonspecific DNA binding activity. Recombinant rTFIIIC was functionally equivalent to purified yeast TFIIIC, suggesting that the six recombinant subunits are necessary and sufficient to reconstitute a transcriptionally active TFIIIC complex. The formation and the properties of rTFIIIC-DNA complexes were affected by dephosphorylation treatments. The combination of complete recombinant rTFIIIC and rTFIIIB directed a low level of basal transcription, much weaker than with the crude B'' fraction, suggesting the existence of auxiliary factors that could modulate the yeast RNA polymerase III transcription system.
GC-Rich DNA Elements Enable Replication Origin Activity in the Methylotrophic Yeast Pichia pastoris

PubMed Central

Liachko, Ivan; Youngblood, Rachel A.; Tsui, Kyle; Bubb, Kerry L.; Queitsch, Christine; Raghuraman, M. K.; Nislow, Corey; Brewer, Bonita J.; Dunham, Maitreya J.

2014-01-01

The well-studied DNA replication origins of the model budding and fission yeasts are A/T-rich elements. However, unlike their yeast counterparts, both plant and metazoan origins are G/C-rich and are associated with transcription start sites. Here we show that an industrially important methylotrophic budding yeast, Pichia pastoris, simultaneously employs at least two types of replication origins—a G/C-rich type associated with transcription start sites and an A/T-rich type more reminiscent of typical budding and fission yeast origins. We used a suite of massively parallel sequencing tools to map and dissect P. pastoris origins comprehensively, to measure their replication dynamics, and to assay the global positioning of nucleosomes across the genome. Our results suggest that some functional overlap exists between promoter sequences and G/C-rich replication origins in P. pastoris and imply an evolutionary bifurcation of the modes of replication initiation. PMID:24603708
GC-rich DNA elements enable replication origin activity in the methylotrophic yeast Pichia pastoris.

PubMed

Liachko, Ivan; Youngblood, Rachel A; Tsui, Kyle; Bubb, Kerry L; Queitsch, Christine; Raghuraman, M K; Nislow, Corey; Brewer, Bonita J; Dunham, Maitreya J

2014-03-01

The well-studied DNA replication origins of the model budding and fission yeasts are A/T-rich elements. However, unlike their yeast counterparts, both plant and metazoan origins are G/C-rich and are associated with transcription start sites. Here we show that an industrially important methylotrophic budding yeast, Pichia pastoris, simultaneously employs at least two types of replication origins--a G/C-rich type associated with transcription start sites and an A/T-rich type more reminiscent of typical budding and fission yeast origins. We used a suite of massively parallel sequencing tools to map and dissect P. pastoris origins comprehensively, to measure their replication dynamics, and to assay the global positioning of nucleosomes across the genome. Our results suggest that some functional overlap exists between promoter sequences and G/C-rich replication origins in P. pastoris and imply an evolutionary bifurcation of the modes of replication initiation.
Experimental Systems to Study Yeast Pexophagy.

PubMed

Yamashita, Shun-Ichi; Oku, Masahide; Sakai, Yasuyoshi; Fujiki, Yukio

2017-01-01

Peroxisome abundance is tightly regulated according to the physiological contexts, through regulations of both proliferation and degradation of the organelles. Here, we describe detailed methods to analyze processes for autophagic degradation of peroxisomes, termed pexophagy, in yeast organisms. The assay systems include a method for biochemical detection of pexophagy completion, and one for microscopic visualization of specialized membrane structures acting in pexophagy. As a model yeast organism utilized in studies of pexophagy, the methylotrophic yeast Komagataella phaffii (Pichia pastoris) is referred to in this chapter and related information on the studies with baker's yeast (Saccharomyces cerevisiae) is also included. The described techniques facilitate elucidation of molecular machineries for pexophagy and understanding of peroxisome-selective autophagic pathways.
Cytotoxicity and gene induction by some essential oils in the yeast Saccharomyces cerevisiae.

PubMed

Bakkali, F; Averbeck, S; Averbeck, D; Zhiri, A; Idaomar, M

2005-08-01

In order to get an insight into the possible genotoxicity of essential oils (EOs) used in traditional pharmacological applications we tested five different oils extracted from the medicinal plants Origanum compactum, Coriandrum sativum, Artemisia herba alba, Cinnamomum camphora (Ravintsara aromatica) and Helichrysum italicum (Calendula officinalis) for genotoxic effects using the yeast Saccharomyces cerevisiae. Clear cytotoxic effects were observed in the diploid yeast strain D7, with the cells being more sensitive to EOs in exponential than in stationary growth phase. The cytotoxicity decreased in the following order: Origanum compactum>Coriandrum sativum>Artemisia herba alba>Cinnamomum camphora>Helichrysum italicum. In the same order, all EOs, except that derived from Helichrysum italicum, clearly induced cytoplasmic petite mutations indicating damage to mitochondrial DNA. However, no nuclear genetic events such as point mutations or mitotic intragenic or intergenic recombination were induced. The capacity of EOs to induce nuclear DNA damage-responsive genes was tested using suitable Lac-Z fusion strains for RNR3 and RAD51, which are genes involved in DNA metabolism and DNA repair, respectively. At equitoxic doses, all EOs demonstrated significant gene induction, approximately the same as that caused by hydrogen peroxide, but much lower than that caused by methyl methanesulfonate (MMS). EOs affect mitochondrial structure and function and can stimulate the transcriptional expression of DNA damage-responsive genes. The induction of mitochondrial damage by EOs appears to be closely linked to overall cellular cytotoxicity and appears to mask the occurrence of nuclear genetic events. EO-induced cytotoxicity involves oxidative stress, as is evident from the protection observed in the presence of ROS inhibitors such as glutathione, catalase or the iron-chelating agent deferoxamine.
[Distiller Yeasts Producing Antibacterial Peptides].

PubMed

Klyachko, E V; Morozkina, E V; Zaitchik, B Ts; Benevolensky, S V

2015-01-01

A new method of controlling lactic acid bacteria contamination was developed with the use of recombinant Saccharomyces cerevisiae strains producing antibacterial peptides. Genes encoding the antibacterial peptides pediocin and plantaricin with codons preferable for S. cerevisiae were synthesized, and a system was constructed for their secretory expression. Recombinant S. cerevisiae strains producing antibacterial peptides effectively inhibit the growth of Lactobacillus sakei, Pediacoccus pentasaceus, Pediacoccus acidilactici, etc. The application of distiller yeasts producing antibacterial peptides enhances the ethanol yield in cases of bacterial contamination. Recombinant yeasts producing the antibacterial peptides pediocin and plantaricin can successfully substitute the available industrial yeast strains upon ethanol production.
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
Made for Each Other: Ascomycete Yeasts and Insects.

PubMed

Blackwell, Meredith

2017-06-01

Fungi and insects live together in the same habitats, and many species of both groups rely on each other for success. Insects, the most successful animals on Earth, cannot produce sterols, essential vitamins, and many enzymes; fungi, often yeast-like in growth form, make up for these deficits. Fungi, however, require constantly replenished substrates because they consume the previous ones, and insects, sometimes lured by volatile fungal compounds, carry fungi directly to a similar, but fresh, habitat. Yeasts associated with insects include Ascomycota (Saccharomycotina, Pezizomycotina) and a few Basidiomycota. Beetles, homopterans, and flies are important associates of fungi, and in turn the insects carry yeasts in pits, specialized external pouches, and modified gut pockets. Some yeasts undergo sexual reproduction within the insect gut, where the genetic diversity of the population is increased, while others, well suited to their stable environment, may never mate. The range of interactions extends from dispersal of yeasts on the surface of insects (e.g., cactus- Drosophila -yeast and ephemeral flower communities, ambrosia beetles, yeasts with holdfasts) to extremely specialized associations of organisms that can no longer exist independently, as in the case of yeast-like symbionts of planthoppers. In a few cases yeast-like fungus-insect associations threaten butterflies and other species with extinction. Technical advances improve discovery and identification of the fungi but also inform our understanding of the evolution of yeast-insect symbioses, although there is much more to learn.
In situ production of human β defensin-3 in lager yeasts provides bactericidal activity against beer-spoiling bacteria under fermentation conditions.

PubMed

James, T C; Gallagher, L; Titze, J; Bourke, P; Kavanagh, J; Arendt, E; Bond, U

2014-02-01

To examine the use of a natural antimicrobial peptide, human β-defensin-3 (HBD3), as a means of preventing spoilage from bacterial contamination in brewery fermentations and in bottled beer. A chemically synthesised HBD3 peptide was tested for bactericidal activity against common Gram-positive and Gram-negative beer-spoiling bacteria, including species of Lactobacillus, Pediococcus and Pectinatus. The peptide was effective at the μmol l(-1) range in vitro, reducing bacterial counts by 95%. A gene construct encoding a secretable form of HBD3 was integrated into the genome of the lager yeast Saccharomyces pastorianus strain CMBS-33. The integrated gene was expressed under fermentation conditions and was secreted from the cell into the medium, but a significant amount remains associated with yeast cell surface. We demonstrate that under pilot-scale fermentation conditions, secreted HBD3 possesses bactericidal activity against beer-spoiling bacteria. Furthermore, when added to bottled beer, a synthetic form of HBD3 reduces the growth of beer-spoiling bacteria. Defensins provide prophylactic protection against beer-spoiling bacteria under brewing conditions and also in bottled beer. The results have direct application to the brewing industry where beer spoilage due to bacterial contamination continues to be a major problem in breweries around the world. © 2013 The Society for Applied Microbiology.
Diverse RNA-binding proteins interact with functionally related sets of RNAs, suggesting an extensive regulatory system.

PubMed

Hogan, Daniel J; Riordan, Daniel P; Gerber, André P; Herschlag, Daniel; Brown, Patrick O

2008-10-28

RNA-binding proteins (RBPs) have roles in the regulation of many post-transcriptional steps in gene expression, but relatively few RBPs have been systematically studied. We searched for the RNA targets of 40 proteins in the yeast Saccharomyces cerevisiae: a selective sample of the approximately 600 annotated and predicted RBPs, as well as several proteins not annotated as RBPs. At least 33 of these 40 proteins, including three of the four proteins that were not previously known or predicted to be RBPs, were reproducibly associated with specific sets of a few to several hundred RNAs. Remarkably, many of the RBPs we studied bound mRNAs whose protein products share identifiable functional or cytotopic features. We identified specific sequences or predicted structures significantly enriched in target mRNAs of 16 RBPs. These potential RNA-recognition elements were diverse in sequence, structure, and location: some were found predominantly in 3'-untranslated regions, others in 5'-untranslated regions, some in coding sequences, and many in two or more of these features. Although this study only examined a small fraction of the universe of yeast RBPs, 70% of the mRNA transcriptome had significant associations with at least one of these RBPs, and on average, each distinct yeast mRNA interacted with three of the RBPs, suggesting the potential for a rich, multidimensional network of regulation. These results strongly suggest that combinatorial binding of RBPs to specific recognition elements in mRNAs is a pervasive mechanism for multi-dimensional regulation of their post-transcriptional fate.
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.
The growth of solar radiated yeast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kraft, T.

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 containersmore » 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.« less
Structural and Biochemical Insights into the Multiple Functions of Yeast Grx3.

PubMed

Chi, Chang-Biao; Tang, YaJun; Zhang, Jiahai; Dai, Ya-Nan; Abdalla, Mohnad; Chen, Yuxing; Zhou, Cong-Zhao

2018-04-13

The yeast Saccharomyces cerevisiae monothiol glutaredoxin Grx3 plays a key role in cellular defense against oxidative stress and more importantly, cooperates with BolA-like iron repressor of activation protein Fra2 to regulate the localization of the iron-sensing transcription factor Aft2. The interplay among Grx3, Fra2 and Aft2 responsible for the regulation of iron homeostasis has not been clearly described. Here we solved the crystal structures of the Trx domain (Grx3 Trx ) and Grx domain (Grx3 Grx ) of Grx3 in addition to the solution structure of Fra2. Structural analyses and activity assays indicated that the Trx domain also contributes to the glutathione S-transferase activity of Grx3, via an inter-domain disulfide bond between Cys37 and Cys176. NMR titration and pull-down assays combined with surface plasmon resonance experiments revealed that Fra2 could form a noncovalent heterodimer with Grx3 via an interface between the helix-turn-helix motif of Fra2 and the C-terminal segment of Grx3 Grx , different from the previously identified covalent heterodimer mediated by Fe-S cluster. Comparative affinity assays indicated that the interaction between Fra2 and Aft2 is much stronger than that between Grx3 and Aft2, or Aft2 toward its target DNA. These structural and biochemical analyses enabled us to propose a model how Grx3 executes multiple functions to coordinate the regulation of Aft2-controlled iron metabolism. Copyright © 2018 Elsevier Ltd. All rights reserved.
Both H4K20 mono-methylation and H3K56 acetylation mark transcription-dependent histone turnover in fission yeast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Hanna; Kwon, Chang Seob; Choi, Yoonjung, E-mail: jjungii@kaist.ac.kr

Nucleosome dynamics facilitated by histone turnover is required for transcription as well as DNA replication and repair. Histone turnover is often associated with various histone modifications such as H3K56 acetylation (H3K56Ac), H3K36 methylation (H3K36me), and H4K20 methylation (H4K20me). In order to correlate histone modifications and transcription-dependent histone turnover, we performed genome wide analyses for euchromatic regions in G2/M-arrested fission yeast. The results show that transcription-dependent histone turnover at 5′ promoter and 3′ termination regions is directly correlated with the occurrence of H3K56Ac and H4K20 mono-methylation (H4K20me1) in actively transcribed genes. Furthermore, the increase of H3K56Ac and H4K20me1 and antisense RNAmore » production was observed in the absence of the histone H3K36 methyltransferase Set2 and histone deacetylase complex (HDAC) that are involved in the suppression of histone turnover within the coding regions. These results together indicate that H4K20me1 as well as H3K56Ac are bona fide marks for transcription-dependent histone turnover in fission yeast.« less
Trans-Lesion DNA Polymerases May Be Involved in Yeast Meiosis

PubMed Central

Arbel-Eden, Ayelet; Joseph-Strauss, Daphna; Masika, Hagit; Printzental, Oxana; Rachi, Eléanor; Simchen, Giora

2013-01-01

Trans-lesion DNA polymerases (TLSPs) enable bypass of DNA lesions during replication and are also induced under stress conditions. Being only weakly dependent on their template during replication, TLSPs introduce mutations into DNA. The low processivity of these enzymes ensures that they fall off their template after a few bases are synthesized and are then replaced by the more accurate replicative polymerase. We find that the three TLSPs of budding yeast Saccharomyces cerevisiae Rev1, PolZeta (Rev3 and Rev7), and Rad30 are induced during meiosis at a time when DNA double-strand breaks (DSBs) are formed and homologous chromosomes recombine. Strains deleted for one or any combination of the three TLSPs undergo normal meiosis. However, in the triple-deletion mutant, there is a reduction in both allelic and ectopic recombination. We suggest that trans-lesion polymerases are involved in the processing of meiotic double-strand breaks that lead to mutations. In support of this notion, we report significant yeast two-hybrid (Y2H) associations in meiosis-arrested cells between the TLSPs and DSB proteins Rev1-Spo11, Rev1-Mei4, and Rev7-Rec114, as well as between Rev1 and Rad30. We suggest that the involvement of TLSPs in processing of meiotic DSBs could be responsible for the considerably higher frequency of mutations reported during meiosis compared with that found in mitotically dividing cells, and therefore may contribute to faster evolutionary divergence than previously assumed. PMID:23550131
Pigeons and their droppings as reservoirs of Candida and other zoonotic yeasts.

PubMed

Rosario Medina, Inmaculada; Román Fuentes, Lorena; Batista Arteaga, Miguel; Real Valcárcel, Fernando; Acosta Arbelo, Félix; Padilla Del Castillo, Daniel; Déniz Suárez, Soraya; Ferrer Quintana, Otilia; Vega Gutiérrez, Belinda; Silva Sergent, Freddy; Acosta-Hernández, Begoña

The importance of pigeons as reservoirs and carriers of Cryptococcus neoformans and other species of this genus is well-known; however, less is known about their role as reservoirs and carriers of other yeasts that impact public health. The present study was performed on Gran Canaria Island to define yeasts other than Cryptococcus spp. that have been reported to impact public health and which could be carried by pigeons. Samples were obtained from 83 pigeon lofts (Columba livia); moreover, 331 crop samples, 331 cloacal samples and 174 dropping samples were collected. In addition, 17 dropping samples were taken from a total of 17 public squares. Samples were inoculated on Sabouraud dextrose agar with chloramphenicol. Different yeast species, i.e. Candida guilliermondii (24.36%), Candida kefyr (1.21%), Saccharomyces cerevisiae (2.43%), and Trichosporon asahii (1.21%) were isolated for the first time from the cloaca. The most frequently isolated yeast from the crop, cloaca and dropping samples from lofts was C. guilliermondii (30.46%, 24.36% and 49.37%, respectively). In addition, for the first time, C. kefyr (3.65%), Candida pelliculosa (2.43%), Candida rugosa (1.21%), T. asahii (3.65%), Trichosporon mucoides (3.65%) and Prototheca wickerhamii (1.21%) were obtained from crop samples; Candida pelliculosa (1.20%), T. asahii (9.63%) and T. mucoides (7.22%) were isolated from dropping samples in the lofts. Candida albicans was the most frequently isolated yeast in dropping samples collected in public squares. It can be assumed that pigeons and their droppings act as carriers and reservoirs of Candida spp. and other zoonotic yeasts. Copyright © 2017 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

Transformation of Mycelial and Yeast Forms of Paracoccidioides brasiliensis in Cultures and in Experimental Inoculations

PubMed Central

Carbonell, Luis M.; Rodríguez, Joaquín

1965-01-01

Carbonell, Luis M. (Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela), and Joaquín Rodríguez. Transformation of mycelial and yeast forms of Paracoccidioides brasiliensis in cultures and in experimental inoculations. J. Bacteriol. 90:504–510. 1965.—Experimental transformations of mycelial to yeast and yeast to mycelial forms in culture, and mycelial to yeast forms in tissue, were studied. All the transitional forms that appeared in culture were also seen in tissue, but in fewer number. Most of the hyphae in culture were transformed into yeast, but only a few in tissue. Yeast appeared in testicle around the 3rd day after inoculation, but on the 10th day in subcutaneous tissue. Pathogenicity of mycelium was high, since yeast was found in almost all of the organs inoculated with mycelium. Histologically, an acute inflammation occurred first, owing to the inoculation of mycelium, followed by a giant-cell granuloma with abundant hyphae detritus. These giant cells almost disappeared about 10 days after inoculation, giving place to a second giant-cell granuloma with yeast forms. Images PMID:14329466
Population analysis of biofilm yeasts during fino sherry wine aging in the Montilla-Moriles D.O. region.

PubMed

Marin-Menguiano, Miriam; Romero-Sanchez, Sandra; Barrales, Ramón R; Ibeas, Jose I

2017-03-06

Fino is the most popular sherry wine produced in southern Spain. Fino is matured by biological aging under a yeast biofilm constituted of Saccharomyces cerevisiae yeasts. Although different S. cerevisiae strains can be identified in such biofilms, their diversity and contribution to wine character have been poorly studied. In this work, we analyse the flor yeast population in five different wineries from the Montilla-Moriles D.O. (Denominación de Origen) in southern Spain. Yeasts present in wines of different ages were identified using two different culture-dependent molecular techniques. From 2000 individual yeast isolates, five different strains were identified with one of them dominating in four out of the five wineries analysed, and representing 76% of all the yeast isolates collected. Surprisingly, this strain is similar to the predominant strain isolated twenty years ago in Jerez D.O. wines, suggesting that this yeast is particularly able to adapt to such a stressful environment. Fino wine produced with pure cultures of three of the isolated strains resulted in different levels of acetaldehyde. Because acetaldehyde levels are a distinctive characteristic of fino wines and an indicator of fino aging, the use of molecular techniques for yeast identification and management of yeast populations may be of interest for fino wine producers looking to control one of the main features of this wine. Copyright © 2016 Elsevier B.V. All rights reserved.
Biotechnology of non-Saccharomyces yeasts--the ascomycetes.

PubMed

Johnson, Eric A

2013-01-01

Saccharomyces cerevisiae and several other yeast species are among the most important groups of biotechnological organisms. S. cerevisiae and closely related ascomycetous yeasts are the major producer of biotechnology products worldwide, exceeding other groups of industrial microorganisms in productivity and economic revenues. Traditional industrial attributes of the S. cerevisiae group include their primary roles in food fermentations such as beers, cider, wines, sake, distilled spirits, bakery products, cheese, sausages, and other fermented foods. Other long-standing industrial processes involving S. cerevisae yeasts are production of fuel ethanol, single-cell protein (SCP), feeds and fodder, industrial enzymes, and small molecular weight metabolites. More recently, non-Saccharomyces yeasts (non-conventional yeasts) have been utilized as industrial organisms for a variety of biotechnological roles. Non-Saccharomyces yeasts are increasingly being used as hosts for expression of proteins, biocatalysts and multi-enzyme pathways for the synthesis of fine chemicals and small molecular weight compounds of medicinal and nutritional importance. Non-Saccharomyces yeasts also have important roles in agriculture as agents of biocontrol, bioremediation, and as indicators of environmental quality. Several of these products and processes have reached commercial utility, while others are in advanced development. The objective of this mini-review is to describe processes currently used by industry and those in developmental stages and close to commercialization primarily from non-Saccharomyces yeasts with an emphasis on new opportunities. The utility of S. cerevisiae in heterologous production of selected products is also described.
Yeast proteome map (last update).

PubMed

Perrot, Michel; Moes, Suzette; Massoni, Aurélie; Jenoe, Paul; Boucherie, Hélian

2009-10-01

The identification of proteins separated on 2-D gels is essential to exploit the full potential of 2-D gel electrophoresis for proteomic investigations. For this purpose we have undertaken the systematic identification of Saccharomyces cerevisiae proteins separated on 2-D gels. We report here the identification by mass spectrometry of 100 novel yeast protein spots that have so far not been tackled due to their scarcity on our standard 2-D gels. These identifications extend the number of protein spots identified on our yeast 2-D proteome map to 716. They correspond to 485 unique proteins. Among these, 154 were resolved into several isoforms. The present data set can now be expanded to report for the first time a map of 363 protein isoforms that significantly deepens our knowledge of the yeast proteome. The reference map and a list of all identified proteins can be accessed on the Yeast Protein Map server (www.ibgc.u-bordeaux2.fr/YPM).
The fascinating and secret wild life of the budding yeast S. cerevisiae

PubMed Central

Liti, Gianni

2015-01-01

The budding yeast Saccharomyces cerevisiae has been used in laboratory experiments for over a century and has been instrumental in understanding virtually every aspect of molecular biology and genetics. However, it wasn't until a decade ago that the scientific community started to realise how little was known about this yeast's ecology and natural history, and how this information was vitally important for interpreting its biology. Recent large-scale population genomics studies coupled with intensive field surveys have revealed a previously unappreciated wild lifestyle of S. cerevisiae outside the restrictions of human environments and laboratories. The recent discovery that Chinese isolates harbour almost twice as much genetic variation as isolates from the rest of the world combined suggests that Asia is the likely origin of the modern budding yeast. DOI: http://dx.doi.org/10.7554/eLife.05835.001 PMID:25807086
Septin Organization and Functions in Budding Yeast

PubMed Central

Glomb, Oliver; Gronemeyer, Thomas

2016-01-01

The septins are a conserved family of GTP-binding proteins present in all eukaryotic cells except plants. They were originally discovered in the baker's yeast Saccharomyces cerevisiae that serves until today as an important model organism for septin research. In yeast, the septins assemble into a highly ordered array of filaments at the mother bud neck. The septins are regulators of spatial compartmentalization in yeast and act as key players in cytokinesis. This minireview summarizes the recent findings about structural features and cell biology of the yeast septins. PMID:27857941
Diversity of culturable yeasts associated with zoanthids from Brazilian reef and its relation with anthropogenic disturbance.

PubMed

Paulino, Gustavo Vasconcelos Bastos; Félix, Ciro Ramon; Broetto, Leonardo; Landell, Melissa Fontes

2017-10-15

Some of the main threats to coral reefs come from human actions on marine environment, such as tourism, overfishing and pollution from urban development. While several studies have demonstrated an association between bacteria and corals, demonstrating how these communities react to different anthropogenic stressors, yeast communities associated with corals have received far less attention from researchers. The aim of this work was therefore to describe cultivable yeasts associated with three coral species and to evaluate the influence of sewage discharge on yeasts community. We obtained 130 isolates, mostly belonging to phylum Ascomycota and many of them had previously been isolated from human samples or are considered pathogens. The mycobiota was more similar among corals collected from the same reef, indicating that the composition of reef yeast community is more influenced by environmental conditions than host species. We suggest further studies to elucidate which factors are most influential on the composition of the coral-associated yeast community. Copyright © 2017 Elsevier Ltd. All rights reserved.
Origins of multicellular evolvability in snowflake yeast

PubMed Central

Ratcliff, William C.; Fankhauser, Johnathon D.; Rogers, David W.; Greig, Duncan; Travisano, Michael

2015-01-01

Complex life has arisen through a series of ‘major transitions’ in which collectives of formerly autonomous individuals evolve into a single, integrated organism. A key step in this process is the origin of higher-level evolvability, but little is known about how higher-level entities originate and gain the capacity to evolve as an individual. Here we report a single mutation that not only creates a new level of biological organization, but also potentiates higher-level evolvability. Disrupting the transcription factor ACE2 in Saccharomyces cerevisiae prevents mother–daughter cell separation, generating multicellular ‘snowflake’ yeast. Snowflake yeast develop through deterministic rules that produce geometrically defined clusters that preclude genetic conflict and display a high broad-sense heritability for multicellular traits; as a result they are preadapted to multicellular adaptation. This work demonstrates that simple microevolutionary changes can have profound macroevolutionary consequences, and suggests that the formation of clonally developing clusters may often be the first step to multicellularity. PMID:25600558
Yeast 5 – an expanded reconstruction of the Saccharomyces cerevisiae metabolic network

PubMed Central

2012-01-01

Background Efforts to improve the computational reconstruction of the Saccharomyces cerevisiae biochemical reaction network and to refine the stoichiometrically constrained metabolic models that can be derived from such a reconstruction have continued since the first stoichiometrically constrained yeast genome scale metabolic model was published in 2003. Continuing this ongoing process, we have constructed an update to the Yeast Consensus Reconstruction, Yeast 5. The Yeast Consensus Reconstruction is a product of efforts to forge a community-based reconstruction emphasizing standards compliance and biochemical accuracy via evidence-based selection of reactions. It draws upon models published by a variety of independent research groups as well as information obtained from biochemical databases and primary literature. Results Yeast 5 refines the biochemical reactions included in the reconstruction, particularly reactions involved in sphingolipid metabolism; updates gene-reaction annotations; and emphasizes the distinction between reconstruction and stoichiometrically constrained model. Although it was not a primary goal, this update also improves the accuracy of model prediction of viability and auxotrophy phenotypes and increases the number of epistatic interactions. This update maintains an emphasis on standards compliance, unambiguous metabolite naming, and computer-readable annotations available through a structured document format. Additionally, we have developed MATLAB scripts to evaluate the model’s predictive accuracy and to demonstrate basic model applications such as simulating aerobic and anaerobic growth. These scripts, which provide an independent tool for evaluating the performance of various stoichiometrically constrained yeast metabolic models using flux balance analysis, are included as Additional files 1, 2 and 3. Conclusions Yeast 5 expands and refines the computational reconstruction of yeast metabolism and improves the predictive accuracy of a
Taming wild yeast: potential of conventional and nonconventional yeasts in industrial fermentations.

PubMed

Steensels, Jan; Verstrepen, Kevin J

2014-01-01

Yeasts are the main driving force behind several industrial food fermentation processes, including the production of beer, wine, sake, bread, and chocolate. Historically, these processes developed from uncontrolled, spontaneous fermentation reactions that rely on a complex mixture of microbes present in the environment. Because such spontaneous processes are generally inconsistent and inefficient and often lead to the formation of off-flavors, most of today's industrial production utilizes defined starter cultures, often consisting of a specific domesticated strain of Saccharomyces cerevisiae, S. bayanus, or S. pastorianus. Although this practice greatly improved process consistency, efficiency, and overall quality, it also limited the sensorial complexity of the end product. In this review, we discuss how Saccharomyces yeasts were domesticated to become the main workhorse of food fermentations, and we investigate the potential and selection of nonconventional yeasts that are often found in spontaneous fermentations, such as Brettanomyces, Hanseniaspora, and Pichia spp.
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)
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.
Detection of yeast Saccharomyces cerevisiae with ionic liquid mediated carbon dots.

PubMed

Wang, Jia-Li; Teng, Ji-Yuan; Jia, Te; Shu, Yang

2018-02-01

Hydrophobic nitrogen-doped carbon dots are prepared with energetic ionic liquid (1,3-dibutylimidazolium dicyandiamide, BbimDCN) as carbon source. A yield of as high as 58% is obtained for the carbon dots, shortly termed as BbimDCN-OCDs, due to the presence of thermal-instable N(CN) 2 - moiety. BbimDCN-OCDs exhibit favorable biocompability and excellent imaging capacity for fluorescence labelling of yeast cell Saccharomyces cerevisiae. In addition, chitosan-modified Dy 3+ -doped magnetic nanoparticles (shortly as Chitosan@Fe 2.75 Dy 0.25 O 4 ) with superparamagnetism are prepared. The electrostatic attraction between positively charged magnetic nanoparticles and negatively charged yeast cells facilitates exclusive recognition/isolation of S. cerevisiae. In practice, S. cerevisiae is labelled by BbimDCN-OCDs and adhered onto the Chitosan@Fe 2.75 Dy 0.25 O 4 . The yeast/ BbimDCN-OCDs/Chitosan@Fe 2.75 Dy 0.25 O 4 composite is then isolated with an external magnet and the fluorescence from BbimDCN-OCDs incorporated in S. cerevisiae is monitored. The fluorescence intensity is linearly correlated with the content of yeast cell, showing a calibration graph of F = 3.01log[C]+11.7, offering a detection limit of 5×10 2 CFU/mL. S. cerevisiae content in various real sample matrixes are quantified by using this protocol. Copyright © 2017 Elsevier B.V. All rights reserved.
Impact of zinc supplementation on the improvement of ethanol tolerance and yield of self-flocculating yeast in continuous ethanol fermentation.

PubMed

Zhao, X Q; Xue, C; Ge, X M; Yuan, W J; Wang, J Y; Bai, F W

2009-01-01

The effects of zinc supplementation were investigated in the continuous ethanol fermentation using self-flocculating yeast. Zinc sulfate was added at the concentrations of 0.01, 0.05 and 0.1 g l(-1), respectively. Reduced average floc sizes were observed in all the zinc-supplemented cultures. Both the ethanol tolerance and thermal tolerance were significantly improved by zinc supplements, which correlated well with the increased ergosterol and trehalose contents in the yeast flocs. The highest ethanol concentration by 0.05 g l(-1) zinc sulfate supplementation attained 114.5 g l(-1), in contrast to 104.1 g l(-1) in the control culture. Glycerol production was decreased by zinc supplementations, with the lowest level 3.21 g l(-1), about 58% of the control. Zinc content in yeast cells was about 1.4 microMol g(-1) dry cell weight, about sixfold higher than that of control in all the zinc-supplemented cultures, and close correlation of zinc content in yeast cells with the cell viability against ethanol and heat shock treatment was observed. These studies suggest that exogenous zinc addition led to a reprogramming of cellular metabolic network, resulting in enhanced ethanol tolerance and ethanol production.
Comparative Analysis of Mitochondrial N-Termini from Mouse, Human, and Yeast *

PubMed Central

Clauser, Karl R.; Shen, Hongying; Kamer, Kimberli J.; Wells, James A.

2017-01-01

The majority of mitochondrial proteins are encoded in the nuclear genome, translated in the cytoplasm, and directed to the mitochondria by an N-terminal presequence that is cleaved upon import. Recently, N-proteome catalogs have been generated for mitochondria from yeast and from human U937 cells. Here, we applied the subtiligase method to determine N-termini for 327 proteins in mitochondria isolated from mouse liver and kidney. Comparative analysis between mitochondrial N-termini from mouse, human, and yeast proteins shows that whereas presequences are poorly conserved at the sequence level, other presequence properties are extremely conserved, including a length of ∼20–60 amino acids, a net charge between +3 to +6, and the presence of stabilizing amino acids at the N-terminus of mature proteins that follow the N-end rule from bacteria. As in yeast, ∼80% of mouse presequence cleavage sites match canonical motifs for three mitochondrial peptidases (MPP, Icp55, and Oct1), whereas the remainder do not match any known peptidase motifs. We show that mature mitochondrial proteins often exist with a spectrum of N-termini, consistent with a model of multiple cleavage events by MPP and Icp55. In addition to analysis of canonical targeting presequences, our N-terminal dataset allows the exploration of other cleavage events and provides support for polypeptide cleavage into two distinct enzymes (Hsd17b4), protein cleavages key for signaling (Oma1, Opa1, Htra2, Mavs, and Bcs2l13), and in several cases suggests novel protein isoforms (Scp2, Acadm, Adck3, Hsdl2, Dlst, and Ogdh). We present an integrated catalog of mammalian mitochondrial N-termini that can be used as a community resource to investigate individual proteins, to elucidate mechanisms of mammalian mitochondrial processing, and to allow researchers to engineer tags distally to the presequence cleavage. PMID:28122942
Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption

PubMed Central

Luo, Ying; Wang, Jianguo; Liu, Bin; Wang, Zhouli; Yuan, Yahong; Yue, Tianli

2015-01-01

The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry. PMID:26295574
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. © 2017 Molecular Biology Society of Japan and John Wiley & Sons Australia, Ltd.
Genetic Analysis of mlh3 Mutations Reveals Interactions Between Crossover Promoting Factors During Meiosis in Baker’s Yeast

PubMed Central

Brown, Megan Sonntag; Lim, Elisha; Chen, Cheng; Nishant, K. T.; Alani, Eric

2013-01-01

Crossing over between homologous chromosomes occurs during the prophase of meiosis I and is critical for chromosome segregation. In baker’s yeast, two heterodimeric complexes, Msh4-Msh5 and Mlh1-Mlh3, act in meiosis to promote interference-dependent crossing over. Mlh1-Mlh3 also plays a role in DNA mismatch repair (MMR) by interacting with Msh2-Msh3 to repair insertion and deletion mutations. Mlh3 contains an ATP-binding domain that is highly conserved among MLH proteins. To explore roles for Mlh3 in meiosis and MMR, we performed a structure−function analysis of eight mlh3 ATPase mutants. In contrast to previous work, our data suggest that ATP hydrolysis by both Mlh1 and Mlh3 is important for both meiotic and MMR functions. In meiotic assays, these mutants showed a roughly linear relationship between spore viability and genetic map distance. To further understand the relationship between crossing over and meiotic viability, we analyzed crossing over on four chromosomes of varying lengths in mlh3Δ mms4Δ strains and observed strong decreases (6- to 17-fold) in crossing over in all intervals. Curiously, mlh3Δ mms4Δ double mutants displayed spore viability levels that were greater than observed in mms4Δ strains that show modest defects in crossing over. The viability in double mutants also appeared greater than would be expected for strains that show such severe defects in crossing over. Together, these observations provide insights for how Mlh1-Mlh3 acts in crossover resolution and MMR and for how chromosome segregation in Meiosis I can occur in the absence of crossing over. PMID:23316435
Tanshinones extend chronological lifespan in budding yeast Saccharomyces cerevisiae.

PubMed

Wu, Ziyun; Song, Lixia; Liu, Shao Quan; Huang, Dejian

2014-10-01

Natural products with anti-aging property have drawn great attention recently but examples of such compounds are exceedingly scarce. By applying a high-throughput assay based on yeast chronological lifespan measurement, we screened the anti-aging activity of 144 botanical materials and found that dried roots of Salvia miltiorrhiza Bunge have significant anti-aging activity. Tanshinones isolated from the plant including cryptotanshione, tanshinone I, and tanshinone IIa, are the active components. Among them, cryptotanshinone can greatly extend the budding yeast Saccharomyces cerevisiae chronological lifespan (up to 2.5 times) in a dose- and the-time-of-addition-dependent manner at nanomolar concentrations without disruption of cell growth. We demonstrate that cryptotanshinone prolong chronological lifespan via a nutrient-dependent regime, especially essential amino acid sensing, and three conserved protein kinases Tor1, Sch9, and Gcn2 are required for cryptotanshinone-induced lifespan extension. In addition, cryptotanshinone significantly increases the lifespan of SOD2-deleted mutants. Altogether, those data suggest that cryptotanshinone might be involved in the regulation of, Tor1, Sch9, Gcn2, and Sod2, these highly conserved longevity proteins modulated by nutrients from yeast to humans.
Yeasts of the genital region of patients attending the dermatology service at Hospital São Paulo, Brazil.

PubMed

Bentubo, Henri Donnarumma Levy; Mantovani, Ariane; Yamashita, Jane Tomimori; Gambale, Walderez; Fischman, Olga

2015-01-01

The knowledge of the diversity of yeasts that make up the skin microbiota of human beings is essential for the efficient monitoring of infections to which a person may be predisposed. This study identified yeasts comprising the genital skin microbiota of patients attending the Dermatology Service at the Hospital São Paulo-UNIFESP, Brazil. Samples were collected from the genital region of each patient and cultured on Sabouraud dextrose agar. Individual colonies were carefully transferred to tubes daily. Yeasts were identified based on classical methodologies and confirmed using a commercial kit. Eighty-three patients were included in the study. Approximately 80% were women and 20% were men. The average age was 55 years. Hypertension, diabetes, kidney transplant and AIDS were the main underlying diseases reported by the patients. The most prevalent yeasts were Candida parapsilosis (36.1%), Rhodotorula mucilaginosa (9.2%), Rhodotorula glutinis (8.3%), Candida tropicalis (5.5%) and Trichosporon inkin (1.8%). Approximately 78% of the isolates were obtained in pure cultures. Trichosporon inkin was isolated only from women, in contrast to literature describing a high prevalence in males. Our results suggest that Candida albicans is not the main yeast found on genital skin as previously thought, and opportunistic pathogens such as C. parapsilosis, C. tropicalis, Rhodotorula spp. and T. inkin make up the genital skin microbiota, representing a risk for infection in immunocompromised subjects. These results also indicate that women are carriers of T. inkin, the etiological agent of white piedra and trichosporonosis. Copyright © 2013 Revista Iberoamericana de Micología. Published by Elsevier Espana. All rights reserved.

Genomic signatures of adaptation to wine biological ageing conditions in biofilm-forming flor yeasts.

PubMed

Coi, A L; Bigey, F; Mallet, S; Marsit, S; Zara, G; Gladieux, P; Galeote, V; Budroni, M; Dequin, S; Legras, J L

2017-04-01

The molecular and evolutionary processes underlying fungal domestication remain largely unknown despite the importance of fungi to bioindustry and for comparative adaptation genomics in eukaryotes. Wine fermentation and biological ageing are performed by strains of S. cerevisiae with, respectively, pelagic fermentative growth on glucose and biofilm aerobic growth utilizing ethanol. Here, we use environmental samples of wine and flor yeasts to investigate the genomic basis of yeast adaptation to contrasted anthropogenic environments. Phylogenetic inference and population structure analysis based on single nucleotide polymorphisms revealed a group of flor yeasts separated from wine yeasts. A combination of methods revealed several highly differentiated regions between wine and flor yeasts, and analyses using codon-substitution models for detecting molecular adaptation identified sites under positive selection in the high-affinity transporter gene ZRT1. The cross-population composite likelihood ratio revealed selective sweeps at three regions, including in the hexose transporter gene HXT7, the yapsin gene YPS6 and the membrane protein coding gene MTS27. Our analyses also revealed that the biological ageing environment has led to the accumulation of numerous mutations in proteins from several networks, including Flo11 regulation and divalent metal transport. Together, our findings suggest that the tuning of FLO11 expression and zinc transport networks are a distinctive feature of the genetic changes underlying the domestication of flor yeasts. Our study highlights the multiplicity of genomic changes underlying yeast adaptation to man-made habitats and reveals that flor/wine yeast lineage can serve as a useful model for studying the genomics of adaptive divergence. © 2017 John Wiley & Sons Ltd.
Role of turgor pressure in endocytosis in fission yeast

PubMed Central

Basu, Roshni; Munteanu, Emilia Laura; Chang, Fred

2014-01-01

Yeast and other walled cells possess high internal turgor pressure that allows them to grow and survive in the environment. This turgor pressure, however, may oppose the invagination of the plasma membrane needed for endocytosis. Here we study the effects of turgor pressure on endocytosis in the fission yeast Schizosaccharomyces pombe by time-lapse imaging of individual endocytic sites. Decreasing effective turgor pressure by addition of sorbitol to the media significantly accelerates early steps in the endocytic process before actin assembly and membrane ingression but does not affect the velocity or depth of ingression of the endocytic pit in wild-type cells. Sorbitol also rescues endocytic ingression defects of certain endocytic mutants and of cells treated with a low dose of the actin inhibitor latrunculin A. Endocytosis proceeds after removal of the cell wall, suggesting that the cell wall does not contribute mechanically to this process. These studies suggest that endocytosis is governed by a mechanical balance between local actin-dependent inward forces and opposing forces from high internal turgor pressure on the plasma membrane. PMID:24403609
The secretory pathway: exploring yeast diversity.

PubMed

Delic, Marizela; Valli, Minoska; Graf, Alexandra B; Pfeffer, Martin; Mattanovich, Diethard; Gasser, Brigitte

2013-11-01

Protein secretion is an essential process for living organisms. In eukaryotes, this encompasses numerous steps mediated by several hundred cellular proteins. The core functions of translocation through the endoplasmic reticulum membrane, primary glycosylation, folding and quality control, and vesicle-mediated secretion are similar from yeasts to higher eukaryotes. However, recent research has revealed significant functional differences between yeasts and mammalian cells, and even among diverse yeast species. This review provides a current overview of the canonical protein secretion pathway in the model yeast Saccharomyces cerevisiae, highlighting differences to mammalian cells as well as currently unresolved questions, and provides a genomic comparison of the S. cerevisiae pathway to seven other yeast species where secretion has been investigated due to their attraction as protein production platforms, or for their relevance as pathogens. The analysis of Candida albicans, Candida glabrata, Kluyveromyces lactis, Pichia pastoris, Hansenula polymorpha, Yarrowia lipolytica, and Schizosaccharomyces pombe reveals that many - but not all - secretion steps are more redundant in S. cerevisiae due to duplicated genes, while some processes are even absent in this model yeast. Recent research obviates that even where homologous genes are present, small differences in protein sequence and/or differences in the regulation of gene expression may lead to quite different protein secretion phenotypes. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.
[Yeast colonization of urinary catheters and the significance of biofilm formation].

PubMed

Růžička, Filip; Holá, Veronika; Mahelová, Martina; Procházková, Alena

2012-08-01

Urinary catheters are colonized by a wide range of microorganisms, including numerous yeasts. The catheters are usually colonized by more microbial species forming a community - multispecies biofilm. Catheter colonization usually does not affect the patient's clinical status in any significant way. On the other hand, the biofilm can become a source of endogenous infection and its presence can affect functionality of the catheter and formation of urinary stones. Material a A total of 721 urinary catheters were studied. Microorganisms were released from catheters by sonication and subsequently cultured. Their identification was performed with the use of common phenotypic tests, as well as using MALDI TOF. Yeasts whose identification was ambiguous were recognized by sequencing. Biofilm formation was assessed by growth in a microtiter plate. Yeast colonization was proved in 244 urinary catheters. However, a total of 274 yeast strains were isolated. Most of them occurred together with other yeast species and/or bacteria on the catheters, producing multispecies biofilm there. The most frequent species was Candida albicans (a total of 144 isolated strains), followed by Candida glabrata (41), Candida tropicalis (41) and Candida parapsilosis sensu stricto (14). Other isolated species were as follows: Candida kefyr (10), Candida krusei (9), Candida fabianii (6), Candida lusitaniae (5), Candida dubliniensis (3) and Saccharomyces cerevisiae (one case). Most of the yeasts rather readily formed a firmly adhering biofilm layer on artificial surfaces.
Comparison of volatile sulphur compound production by cheese-ripening yeasts from methionine and methionine-cysteine mixtures.

PubMed

López Del Castillo-Lozano, M; Delile, A; Spinnler, H E; Bonnarme, P; Landaud, S

2007-07-01

Production of volatile sulphur compounds (VSC) was assessed in culture media supplemented with L-methionine or L-methionine/L-cysteine mixtures, using five cheese-ripening yeasts: Debaryomyces hansenii DH47(8), Kluyveromyces lactis KL640, Geotrichum candidum GC77, Yarrowia lipolytica YL200 and Saccharomyces cerevisiae SC45(3). All five yeasts produced VSC with L-methionine or L-methionine/L-cysteine, but different VSC profiles were found. GC77 and YL200 produced dimethyldisulphide and trace levels of dimethyltrisulphide while DH47(8), KL640 and SC45(3) produced mainly methionol and low levels of methional. S-methylthioacetate was produced by all the yeasts but at different concentrations. DH47(8), KL640 and SC45(3) also produced other minor VSC including 3-methylthiopropyl acetate, ethyl-3-methylthiopropanoate, a thiophenone, and an oxathiane. However, VSC production diminished in a strain-dependent behaviour when L-cysteine was supplemented, even at a low concentration (0.2 g l(-1)). This effect was due mainly to a significant decrease in L-methionine consumption in all the yeasts except YL200. Hydrogen sulphide produced by L-cysteine catabolism did not seem to contribute to VSC generation at the acid pH of yeast cultures. The significance of such results in the cheese-ripening context is discussed.
Isolation and expression of a gene (CGR1) regulated during the yeast-hyphal transition in Candida albicans.

PubMed

Cho, T; Sudoh, M; Tanaka, T; Nakashima, Y; Chibana, H; Kaminishi, H

2001-01-26

We used RNA fingerprinting of arbitrarily primed PCR to isolate genes upregulated during the yeast-hyphal transition in Candida albicans. The sequence and expression of one of these genes (CGR1, Candida growth regulation) are presented. Our results suggest that CGR1 expression is associated with a growth cessation of yeast cells, a prerequisite for germination in this organism.
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. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.
Exopolysaccharides from yeast: insight into optimal conditions for biosynthesis, chemical composition and functional properties - review.

PubMed

Gientka, Iwona; Błażejak, Stanisław; Stasiak-Różańska, Lidia; Chlebowska-Śmigiel, Anna

2015-01-01

xopolysaccharides (EPS) are not a well-established group of metabolites. An industrial scale of this EPS production is limited mainly by low yield biosynthesis. Until now, enzymes and biosynthesis pathways, as well as the role of regulatory genes, have not been described. Some of yeast EPS show antitumor, immunostimulatory and antioxidant activity. Others, absorb heavy metals and can function as bioactive components of food. Also, the potential of yeast EPS as thickeners or stabilizers can be found. Optimal conditions for the biosynthesis of yeast exopolysaccharides require strong oxygenation and low temperature of the culture, due to the physiology of the producer strains. The medium should contain sucrose as a carbon source and ammonium sulfate as inorganic nitrogen source, wherein the C:N ratio in the substrate should be 15:1. The cultures are long and the largest accumulation of polymers is observed after 4 or 5 days of culturing. The structure of yeast EPS is complex which affects the strain and culture condition. The EPS from yeast are linear mannans, pullulan, glucooligosaccharides, galactooligosaccharides and other heteropolysaccharides containing α-1,2; α-1,3; α-1,6; β-1,3; β-1,4 bonds. Mannose and glucose have the largest participation of carbohydrates for. t exopolysaccharides (EPS) are not a well-established group of metabolites. An industrial scale of this EPS production is limited mainly by low yield biosynthesis. Until now, enzymes and biosynthesis pathways, as well as the role of regulatory genes, have not been described. Some of yeast EPS show antitumor, immunostimulatory and antioxidant activity. Others, absorb heavy metals and can function as bioactive components of food. Also, the potential of yeast EPS as thickeners or stabilizers can be found. Optimal conditions for the biosynthesis of yeast exopolysaccharides require strong oxygenation and low temperature of the culture, due to the physiology of the producer strains. The
Screening of binding proteins that interact with Chinese sacbrood virus VP3 capsid protein in Apis cerana larvae cDNA library by the yeast two-hybrid method.

PubMed

Fei, Dongliang; Wei, Dong; Yu, Xiaolei; Yue, Jinjin; Li, Ming; Sun, Li; Jiang, Lili; Li, Yijing; Diao, Qingyun; Ma, Mingxiao

2018-03-15

Chinese sacbrood virus (CSBV) causes larval death and apiary collapse of Apis cerana. VP3 is a capsid protein of CSBV but its function is poorly understood. To determine the function of VP3 and screen for novel binding proteins that interact with VP3, we conducted yeast two-hybrid screening, glutathione S-transferase pull-down, and co-immunoprecipitation assays. Galectin (GAL) is a protein involved in immune regulation and host-pathogen interactions. The yeast two-hybrid screen implicated GAL as a major VP3-binding candidate. The assays showed that the VP3 interacted with GAL. Identification of these cellular targets and clarifying their contributions to the host-pathogen interaction may be useful for the development of novel therapeutic and prevention strategies against CSBV infection. Copyright © 2018 Elsevier B.V. All rights reserved.
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.
Reducing patulin contamination in apple juice by using inactive yeast.

PubMed

Yue, Tianli; Dong, Qinfang; Guo, Caixia; Worobo, Randy W

2011-01-01

The mycotoxin, patulin (4-hydroxy-4H-furo[3,2c]pyran-2[6H]-one), is a secondary metabolite produced mainly in rotten parts of fruits and vegetables, most notably apples and apple products, by a wide range of fungal species in the genera Penicillium, Aspergillus, and Byssochlamys. Due to its mutagenic and teratogenic nature and possible health risks to consumers, many countries have regulations to reduce levels of patulin in apple products. In the present study, reduction of patulin contamination in apple juice by using 10 different inactivated yeast strains was assessed. Our results indicated that nearly twofold differences in biomass existed among the 10 yeast strains. Eight of the 10 inactivated yeast strains could provide >50% patulin reduction in apple juice within 24 h, with the highest reduction rate being >72%. Furthermore, juice quality parameters, i.e., degrees Brix, total sugar, titratable acidity, color value, and clarity, of the treated apple juice were very similar to those of the untreated patulin-free juice. Potential applications of using inactivated yeast strain for patulin control are also discussed.
Proteases and caspase-like activity in the yeast Saccharomyces cerevisiae.

PubMed

Wilkinson, Derek; Ramsdale, Mark

2011-10-01

A variety of proteases have been implicated in yeast PCD (programmed cell death) including the metacaspase Mca1 and the separase Esp1, the HtrA-like serine protease Nma111, the cathepsin-like serine carboxypeptideases and a range of vacuolar proteases. Proteasomal activity is also shown to have an important role in determining cell fate, with both pro- and anti-apoptotic roles. Caspase 3-, 6- and 8-like activities are detected upon stimulation of yeast PCD, but not all of this activity is associated with Mca1, implicating other proteases with caspase-like activity in the yeast cell death response. Global proteolytic events that accompany PCD are discussed alongside a consideration of the conservation of the death-related degradome (both at the level of substrate choice and cleavage site). The importance of both gain-of-function changes in the degradome as well as loss-of-function changes are highlighted. Better understanding of both death-related proteases and their substrates may facilitate the design of future antifungal drugs or the manipulation of industrial yeasts for commercial exploitation.
Spent brewer's yeast extract as an ingredient in cooked hams.

PubMed

Pancrazio, Gaston; Cunha, Sara C; de Pinho, Paula Guedes; Loureiro, Mónica; Meireles, Sónia; Ferreira, Isabel M P L V O; Pinho, Olívia

2016-11-01

This work describes the effect of the incorporation of 1% spent yeast extract into cooked hams. Physical/chemical/sensorial characteristics and changes during 12 and 90days storage were evaluated on control and treated cooked hams processed for 1.5, 2.0, 2.5 or 3h. Spent yeast extract addition increased hardness, chewiness, ash, protein and free amino acid content. Similar volatile profiles were obtained, although there were some quantitative differences. No advantages were observed for increased cooking time. No significant differences were observed for physical and sensorial parameters of cooked hams with spent yeast extract at 12 and 90days post production, but His, aldehydes and esters increased at the end of storage. This behaviour was similar to that observed for control hams. The higher hardness of cooked ham with 1% yeast extract was due to the stronger gel formed during cooking and was maintained during storage. This additive acts as gel stabilizer for cooked ham production and could potentially improve other processing characteristics. Copyright © 2016 Elsevier Ltd. All rights reserved.
Immunogenicity and protective efficacy of yeast extracts containing rotavirus-like particles: a potential veterinary vaccine.

PubMed

Rodríguez-Limas, William A; Pastor, Ana Ruth; Esquivel-Soto, Ernesto; Esquivel-Guadarrama, Fernando; Ramírez, Octavio T; Palomares, Laura A

2014-05-19

Rotavirus is the most common cause of severe diarrhea in many animal species of economic interest. A simple, safe and cost-effective vaccine is required for the control and prevention of rotavirus in animals. In this study, we evaluated the use of Saccharomyces cerevisiae extracts containing rotavirus-like particles (RLP) as a vaccine candidate in an adult mice model. Two doses of 1mg of yeast extract containing rotavirus proteins (between 0.3 and 3 μg) resulted in an immunological response capable of reducing the replication of rotavirus after infection. Viral shedding in all mice groups diminished in comparison with the control group when challenged with 100 50% diarrhea doses (DD50) of murine rotavirus strain EDIM. Interestingly, when immunizing intranasally protection against rotavirus infection was observed even when no increase in rotavirus-specific antibody titers was evident, suggesting that cellular responses were responsible of protection. Our results indicate that raw yeast extracts containing rotavirus proteins and RLP are a simple, cost-effective alternative for veterinary vaccines against rotavirus. Copyright © 2014 Elsevier Ltd. All rights reserved.
Genomic Evolution of the Ascomycete Yeasts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riley, Robert; Haridas, Sajeet; Salamov, Asaf

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 amore » 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.« less
The importance of aeration strategy in fuel alcohol fermentations contaminated with Dekkera/Brettanomyces yeasts.

PubMed

Abbott, D A; Ingledew, W M

2005-11-01

Whole corn mash fermentations infected with industrially-isolated Brettanomyces yeasts were not affected even when viable Brettanomyces yeasts out-numbered Saccharomyces yeasts tenfold at the onset of fermentation. Therefore, aeration, a parameter that is pivotal to the physiology of Dekkera/Brettanomyces yeasts, was investigated in mixed culture fermentations. Results suggest that aeration strategy plays a significant role in Dekkera/Brettanomyces-mediated inhibition of fuel alcohol fermentations. Although growth of Saccharomyces cerevisiae was not impeded, mixed culture fermentations aerated at rates of > or =20 ml air l(-1) mash min(-1) showed decreased ethanol yields and an accumulation of acetic acid. The importance of aeration was examined further in combination with organic acid(s). Growth of Saccharomyces occurred more rapidly than growth of Brettanomyces yeasts in all conditions. The combination of 0.075% (w/v) acetic acid and contamination with Brettanomyces TK 1404W did not negatively impact the final ethanol yield under fermentative conditions. Aeration, however, did prove to be detrimental to final ethanol yields. With the inclusion of aeration in the control condition (no organic acid stress) and in each fermentation containing organic acid(s), the final ethanol yields were decreased. It was therefore concluded that aeration strategy is the key parameter in regards to the negative effects observed in fuel alcohol fermentations infected with Dekkera/Brettanomyces yeasts.
Specialist nectar-yeasts decline with urbanization in Berlin

NASA Astrophysics Data System (ADS)

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

2017-03-01

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.
Accumulation and metabolism of selenium by yeast cells.

PubMed

Kieliszek, Marek; Błażejak, Stanisław; Gientka, Iwona; Bzducha-Wróbel, Anna

2015-07-01

This paper examines the process of selenium bioaccumulation and selenium metabolism in yeast cells. Yeast cells can bind elements in ionic from the environment and permanently integrate them into their cellular structure. Up to now, Saccharomyces cerevisiae, Candida utilis, and Yarrowia lipolytica yeasts have been used primarily in biotechnological studies to evaluate binding of minerals. Yeast cells are able to bind selenium in the form of both organic and inorganic compounds. The process of bioaccumulation of selenium by microorganisms occurs through two mechanisms: extracellular binding by ligands of membrane assembly and intracellular accumulation associated with the transport of ions across the cytoplasmic membrane into the cell interior. During intracellular metabolism of selenium, oxidation, reduction, methylation, and selenoprotein synthesis processes are involved, as exemplified by detoxification processes that allow yeasts to survive under culture conditions involving the elevated selenium concentrations which were observed. Selenium yeasts represent probably the best absorbed form of this element. In turn, in terms of wide application, the inclusion of yeast with accumulated selenium may aid in lessening selenium deficiency in a diet.
Therapeutic activity of a Saccharomyces cerevisiae-based probiotic and inactivated whole yeast on vaginal candidiasis

PubMed Central

Pericolini, Eva; Gabrielli, Elena; Ballet, Nathalie; Sabbatini, Samuele; Roselletti, Elena; Cayzeele Decherf, Amélie; Pélerin, Fanny; Luciano, Eugenio; Perito, Stefano; Jüsten, Peter; Vecchiarelli, Anna

2017-01-01

ABSTRACT Vulvovaginal candidiasis is the most prevalent vaginal infection worldwide and Candida albicans is its major agent. Vulvovaginal candidiasis is characterized by disruption of the vaginal microbiota composition, as happens following large spectrum antibiotic usage. Recent studies support the effectiveness of oral and local probiotic treatment for prevention of recurrent vulvovaginal candidiasis. Saccharomyces cerevisiae is a safe yeast used as, or for, the production of ingredients for human nutrition and health. Here, we demonstrate that vaginal administration of probiotic Saccharomyces cerevisiae live yeast (GI) and, in part, inactivated whole yeast Saccharomyces cerevisiae (IY), used as post-challenge therapeutics, was able to positively influence the course of vaginal candidiasis by accelerating the clearance of the fungus. This effect was likely due to multiple interactions of Saccharomyces cerevisiae with Candida albicans. Both live and inactivated yeasts induced coaggregation of Candida and consequently inhibited its adherence to epithelial cells. However, only the probiotic yeast was able to suppress some major virulence factors of Candida albicans such as the ability to switch from yeast to mycelial form and the capacity to express several aspartyl proteases. The effectiveness of live yeast was higher than that of inactivated whole yeast suggesting that the synergy between mechanical effects and biological effects were dominant over purely mechanical effects. The protection of epithelial cells to Candida-induced damage was also observed. Overall, our data show for the first time that Saccharomyces cerevisiae-based ingredients, particularly the living cells, can exert beneficial therapeutic effects on a widespread vaginal mucosal infection. PMID:27435998
Therapeutic activity of a Saccharomyces cerevisiae-based probiotic and inactivated whole yeast on vaginal candidiasis.

PubMed

Pericolini, Eva; Gabrielli, Elena; Ballet, Nathalie; Sabbatini, Samuele; Roselletti, Elena; Cayzeele Decherf, Amélie; Pélerin, Fanny; Luciano, Eugenio; Perito, Stefano; Jüsten, Peter; Vecchiarelli, Anna

2017-01-02

Vulvovaginal candidiasis is the most prevalent vaginal infection worldwide and Candida albicans is its major agent. Vulvovaginal candidiasis is characterized by disruption of the vaginal microbiota composition, as happens following large spectrum antibiotic usage. Recent studies support the effectiveness of oral and local probiotic treatment for prevention of recurrent vulvovaginal candidiasis. Saccharomyces cerevisiae is a safe yeast used as, or for, the production of ingredients for human nutrition and health. Here, we demonstrate that vaginal administration of probiotic Saccharomyces cerevisiae live yeast (GI) and, in part, inactivated whole yeast Saccharomyces cerevisiae (IY), used as post-challenge therapeutics, was able to positively influence the course of vaginal candidiasis by accelerating the clearance of the fungus. This effect was likely due to multiple interactions of Saccharomyces cerevisiae with Candida albicans. Both live and inactivated yeasts induced coaggregation of Candida and consequently inhibited its adherence to epithelial cells. However, only the probiotic yeast was able to suppress some major virulence factors of Candida albicans such as the ability to switch from yeast to mycelial form and the capacity to express several aspartyl proteases. The effectiveness of live yeast was higher than that of inactivated whole yeast suggesting that the synergy between mechanical effects and biological effects were dominant over purely mechanical effects. The protection of epithelial cells to Candida-induced damage was also observed. Overall, our data show for the first time that Saccharomyces cerevisiae-based ingredients, particularly the living cells, can exert beneficial therapeutic effects on a widespread vaginal mucosal infection.

Radiation-induced mitotic and meiotic aneuploidy in the yeast Saccharomyces cerevisiae.

PubMed

Parry, J M; Sharp, D; Tippins, R S; Parry, E M

1979-06-01

A number of genetic systems are described which in yeast may be used to monitor the induction of chromosome aneuploidy during both mitotic and meiotic cell division. Using these systems we have been able to demonstrate the induction of both monosomic and trisomic cells in mitotically dividing cells and disomic spores in meiotically dividing cells after both UV light and X-ray exposure. The frequency of UV-light-induced monosomic colonies were reduced by post-treatment with photoreactivity light and both UV-light- and X-ray-induced monosomic colonies were reduced by liquid holding post-treatment under non-nutrient conditions. Both responses indicate an involvement of DNA-repair mechanisms in the removal of lesions which may lead to monosomy in yeast. This was further confirmed by the response of an excision-defective yeast strain which showed considerably increased sensitivity to the induction of monosomic colonies by UV-light treatment at low doses. Yeast cultures irradiated at different stages of growth showed variation in their responses to both UV-light and X-rays, cells at the exponential phase of growth show maximum sensitivity to the induction of monosomic colonies at low doses whereas stationary phase cultures showed maximum induction of monosomic colonies at high does. The frequencies of X-ray-induced chromosome aneuploidy during meiosis leading to the production of disomic spores was shown to be dependent upon the stage of meiosis at which the yeast cells were exposed to radiation. Cells which had proceeded beyond the DNA synthetic stage of meiosis were shown to produce disomic spores at considerably lower radiation doses than those cells which had only recently been inoculated into sporulation medium. The results obtained suggest that the yeast sustem may be suitable for the study of sensitivities of the various stages of meiotic cell division to the induction of chromosome aneuploidy after radiation exposure.
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
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)
The yeast Arf-GAP Glo3p is required for the endocytic recycling of cell surface proteins.

PubMed

Kawada, Daiki; Kobayashi, Hiromu; Tomita, Tsuyoshi; Nakata, Eisuke; Nagano, Makoto; Siekhaus, Daria Elisabeth; Toshima, Junko Y; Toshima, Jiro

2015-01-01

Small GTP-binding proteins of the Ras superfamily play diverse roles in intracellular trafficking. Among them, the Rab, Arf, and Rho families function in successive steps of vesicle transport, in forming vesicles from donor membranes, directing vesicle trafficking toward target membranes and docking vesicles onto target membranes. These proteins act as molecular switches that are controlled by a cycle of GTP binding and hydrolysis regulated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). In this study we explored the role of GAPs in the regulation of the endocytic pathway using fluorescently labeled yeast mating pheromone α-factor. Among 25 non-essential GAP mutants, we found that deletion of the GLO3 gene, encoding Arf-GAP protein, caused defective internalization of fluorescently labeled α-factor. Quantitative analysis revealed that glo3Δ cells show defective α-factor binding to the cell surface. Interestingly, Ste2p, the α-factor receptor, was mis-localized from the plasma membrane to the vacuole in glo3Δ cells. Domain deletion mutants of Glo3p revealed that a GAP-independent function, as well as the GAP activity, of Glo3p is important for both α-factor binding and Ste2p localization at the cell surface. Additionally, we found that deletion of the GLO3 gene affects the size and number of Arf1p-residing Golgi compartments and causes a defect in transport from the TGN to the plasma membrane. Furthermore, we demonstrated that glo3Δ cells were defective in the late endosome-to-TGN transport pathway, but not in the early endosome-to-TGN transport pathway. These findings suggest novel roles for Arf-GAP Glo3p in endocytic recycling of cell surface proteins. Copyright © 2014 Elsevier B.V. All rights reserved.
Deciphering the Origin, Evolution, and Physiological Function of the Subtelomeric Aryl-Alcohol Dehydrogenase Gene Family in the Yeast Saccharomyces cerevisiae.

PubMed

Yang, Dong-Dong; de Billerbeck, Gustavo M; Zhang, Jin-Jing; Rosenzweig, Frank; Francois, Jean-Marie

2018-01-01

Homology searches indicate that Saccharomyces cerevisiae strain BY4741 contains seven redundant genes that encode putative aryl-alcohol dehydrogenases (AAD). Yeast AAD genes are located in subtelomeric regions of different chromosomes, and their functional role(s) remain enigmatic. Here, we show that two of these genes, AAD4 and AAD14 , encode functional enzymes that reduce aliphatic and aryl-aldehydes concomitant with the oxidation of cofactor NADPH, and that Aad4p and Aad14p exhibit different substrate preference patterns. Other yeast AAD genes are undergoing pseudogenization. The 5' sequence of AAD15 has been deleted from the genome. Repair of an AAD3 missense mutation at the catalytically essential Tyr 73 residue did not result in a functional enzyme. However, ancestral-state reconstruction by fusing Aad6 with Aad16 and by N-terminal repair of Aad10 restores NADPH-dependent aryl-alcohol dehydrogenase activities. Phylogenetic analysis indicates that AAD genes are narrowly distributed in wood-saprophyte fungi and in yeast that occupy lignocellulosic niches. Because yeast AAD genes exhibit activity on veratraldehyde, cinnamaldehyde, and vanillin, they could serve to detoxify aryl-aldehydes released during lignin degradation. However, none of these compounds induce yeast AAD gene expression, and Aad activities do not relieve aryl-aldehyde growth inhibition. Our data suggest an ancestral role for AAD genes in lignin degradation that is degenerating as a result of yeast's domestication and use in brewing, baking, and other industrial applications. IMPORTANCE Functional characterization of hypothetical genes remains one of the chief tasks of the postgenomic era. Although the first Saccharomyces cerevisiae genome sequence was published over 20 years ago, 22% of its estimated 6,603 open reading frames (ORFs) remain unverified. One outstanding example of this category of genes is the enigmatic seven-member AAD family. Here, we demonstrate that proteins encoded by two
Deciphering the Origin, Evolution, and Physiological Function of the Subtelomeric Aryl-Alcohol Dehydrogenase Gene Family in the Yeast Saccharomyces cerevisiae

PubMed Central

de Billerbeck, Gustavo M.; Zhang, Jin-jing; Rosenzweig, Frank

2017-01-01

ABSTRACT Homology searches indicate that Saccharomyces cerevisiae strain BY4741 contains seven redundant genes that encode putative aryl-alcohol dehydrogenases (AAD). Yeast AAD genes are located in subtelomeric regions of different chromosomes, and their functional role(s) remain enigmatic. Here, we show that two of these genes, AAD4 and AAD14, encode functional enzymes that reduce aliphatic and aryl-aldehydes concomitant with the oxidation of cofactor NADPH, and that Aad4p and Aad14p exhibit different substrate preference patterns. Other yeast AAD genes are undergoing pseudogenization. The 5′ sequence of AAD15 has been deleted from the genome. Repair of an AAD3 missense mutation at the catalytically essential Tyr73 residue did not result in a functional enzyme. However, ancestral-state reconstruction by fusing Aad6 with Aad16 and by N-terminal repair of Aad10 restores NADPH-dependent aryl-alcohol dehydrogenase activities. Phylogenetic analysis indicates that AAD genes are narrowly distributed in wood-saprophyte fungi and in yeast that occupy lignocellulosic niches. Because yeast AAD genes exhibit activity on veratraldehyde, cinnamaldehyde, and vanillin, they could serve to detoxify aryl-aldehydes released during lignin degradation. However, none of these compounds induce yeast AAD gene expression, and Aad activities do not relieve aryl-aldehyde growth inhibition. Our data suggest an ancestral role for AAD genes in lignin degradation that is degenerating as a result of yeast's domestication and use in brewing, baking, and other industrial applications. IMPORTANCE Functional characterization of hypothetical genes remains one of the chief tasks of the postgenomic era. Although the first Saccharomyces cerevisiae genome sequence was published over 20 years ago, 22% of its estimated 6,603 open reading frames (ORFs) remain unverified. One outstanding example of this category of genes is the enigmatic seven-member AAD family. Here, we demonstrate that proteins encoded
Comparative study on the freeze stability of yeast and chemical leavened steamed bread dough.

PubMed

Wang, Pei; Yang, Runqiang; Gu, Zhenxin; Xu, Xueming; Jin, Zhengyu

2017-04-15

The present study comparatively evaluated the evolution of yeast and chemical leavened steamed bread dough (YLD/CLD) quality during freeze/thaw (FT) cycles. The steamed bread quality of CLD was more freeze-stable than that of the YLD after 3 FT cycles. Decreased yeast viability contributed to the loss of gassing power in YLD while no significant differences were observed for CLD during FT cycles. However, faster gas release rate in frozen CLD indicated gas retention loss due to the distortion of gluten network. Glutenin macropolymers (GMP) depolymerization via breakage of inter-chain disulfide (SS) bonds and conversions of α-helix and β-turn to β-sheet structures were the main indicators of gluten deterioration. Gluten network was more vulnerable in frozen YLD, resulting in detectable loss of viscoelasticity. The results suggested that supplement of chemical leavener contributed to a more freeze-tolerant gluten network besides its stable gassing power. Copyright © 2016 Elsevier Ltd. All rights reserved.
Selection and Characterization of Potential Baker's Yeast from Indigenous Resources of Nepal

PubMed Central

Timilsina, Parash Mani; Yadav, Archana; Joshi, Yogesh; Bhujel, Sahansila; Adhikari, Rojina; Neupane, Katyayanee

2017-01-01

The study aims to isolate the yeast strains that could be used effectively as baker's yeast and compare them with the commercial baker's yeast available in the market of Nepal. A total of 10 samples including locally available sources like fruits, Murcha, and a local tree “Dar” were collected from different localities of Bhaktapur, Kavre, and Syangja districts of Nepal, respectively. Following enrichment and fermentation of the samples, 26 yeast strains were isolated using selective medium Wallerstein Laboratory Nutrient Agar. From the differential tests which included morphological and microscopic observation and physiological and biochemical characterization such as nitrate reduction and lactose utilization tests, 8 strains were selected as possible Saccharomyces strain. The selected strains were further assessed for their efficient leavening ability by tests such as ethanol tolerance, osmotolerance, invertase test, and stress exclusion test. The three most potent strains ENG, MUR3B, and SUG1 isolated from grape, Murcha, and sugarcane, respectively, were used in the fermentation and baking of dough. These strains also carried a possibility of being used as industrial baker's yeast. PMID:29387490
Selection and Characterization of Potential Baker's Yeast from Indigenous Resources of Nepal.

PubMed

Karki, Tika B; Timilsina, Parash Mani; Yadav, Archana; Pandey, Gyanu Raj; Joshi, Yogesh; Bhujel, Sahansila; Adhikari, Rojina; Neupane, Katyayanee

2017-01-01

The study aims to isolate the yeast strains that could be used effectively as baker's yeast and compare them with the commercial baker's yeast available in the market of Nepal. A total of 10 samples including locally available sources like fruits, Murcha, and a local tree "Dar" were collected from different localities of Bhaktapur, Kavre, and Syangja districts of Nepal, respectively. Following enrichment and fermentation of the samples, 26 yeast strains were isolated using selective medium Wallerstein Laboratory Nutrient Agar. From the differential tests which included morphological and microscopic observation and physiological and biochemical characterization such as nitrate reduction and lactose utilization tests, 8 strains were selected as possible Saccharomyces strain. The selected strains were further assessed for their efficient leavening ability by tests such as ethanol tolerance, osmotolerance, invertase test, and stress exclusion test. The three most potent strains ENG, MUR3B, and SUG1 isolated from grape, Murcha, and sugarcane, respectively, were used in the fermentation and baking of dough. These strains also carried a possibility of being used as industrial baker's yeast.
Characterization of an AtCCX5 gene from Arabidopsis thaliana that involves in high-affinity K{sup +} uptake and Na{sup +} transport in yeast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xinxin; Zhang, Min; Takano, Tetsuo

Highlights: {yields} The AtCCX5 protein coding a putative cation calcium exchanger was characterized. {yields} AtCCX5 expressed in yeast was localized in the plasma membrane and nuclear periphery. {yields} AtCCX5 protein did not show the same transport properties as the CAXs. {yields} AtCCX5 protein involves in mediating high-affinity K{sup +} uptake in yeast. {yields} AtCCX5 protein also involves in Na{sup +} transport in yeast. -- Abstract: The gene for a putative cation calcium exchanger (CCX) from Arabidopsis thaliana, AtCCX5, was cloned and its function was analyzed in yeast. Green fluorescent protein-tagged AtCCX5 expressed in yeast was localized in the plasma membranemore » and nuclear periphery. The yeast transformants expressing AtCCX5 were created and their growth in the presence of various cations (K{sup +}, Na{sup +}, Ca{sup 2+}, Mg{sup 2+}, Fe{sup 2+}, Cu{sup 2+}, Co{sup 2+}, Cd{sup 2+}, Mn{sup 2+}, Ba{sup 2+}, Ni{sup 2+}, Zn{sup 2+}, and Li{sup +}) were analyzed. AtCCX5 expression was found to affect the response to K{sup +} and Na{sup +} in yeast. The AtCCX5 transformant also showed a little better growth to Zn{sup 2+}. The yeast mutant 9.3 expressing AtCCX5 restored growth of the mutant on medium with low K{sup +} (0.5 mM), and also suppressed its Na{sup +} sensitivity. Ion uptake experiments showed that AtCCX5 mediated relatively high-affinity K{sup +} uptake and was also involved in Na{sup +} transport in yeast. Taken together, these findings suggest that the AtCCX5 is a novel transport protein involves in mediating high-affinity K{sup +} uptake and Na{sup +} transport in yeast.« less
Yeast Methylotrophy and Autophagy in a Methanol-Oscillating Environment on Growing Arabidopsis thaliana Leaves

PubMed Central

Kawaguchi, Kosuke; Yurimoto, Hiroya; Oku, Masahide; Sakai, Yasuyoshi

2011-01-01

The yeast Candida boidinii capable of growth on methanol proliferates and survives on the leaves of Arabidopsis thaliana. The local methanol concentration at the phyllosphere of growing A. thaliana exhibited daily periodicity, and yeast cells responded by altering both the expression of methanol-inducible genes and peroxisome proliferation. Even under these dynamically changing environmental conditions, yeast cells proliferated 3 to 4 times in 11 days. Among the C1-metabolic enzymes, enzymes in the methanol assimilation pathway, but not formaldehyde dissimilation or anti-oxidizing enzymes, were necessary for yeast proliferation at the phyllosphere. Furthermore, both peroxisome assembly and pexophagy, a selective autophagy pathway that degrades peroxisomes, were necessary for phyllospheric proliferation. Thus, the present study sheds light on the life cycle and physiology of yeast in the natural environment at both the molecular and cellular levels. PMID:21966472
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.
Recovery of Fuel-Precursor Lipids from Oleaginous Yeast

DOE PAGES

Kruger, Jacob S.; Cleveland, Nicholas S.; Yeap, Rou Yi; ...

2018-01-24

comprised mainly of palmitic, stearic, and oleic acids, with smaller fractions of polar lipids. The fatty acid composition of the lipids extracted from the wet treated cell mass is the same as that in freeze-dried whole oleaginous yeast cell mass, suggesting the acid treatment renders all lipids extractable. This work demonstrates that acid treatment is a robust and effective cell lysis technique in a microbial lipid-based biofuel scenario and provides a baseline for further scale-up and process integration.« less
Recovery of Fuel-Precursor Lipids from Oleaginous Yeast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kruger, Jacob S.; Cleveland, Nicholas S.; Yeap, Rou Yi

comprised mainly of palmitic, stearic, and oleic acids, with smaller fractions of polar lipids. The fatty acid composition of the lipids extracted from the wet treated cell mass is the same as that in freeze-dried whole oleaginous yeast cell mass, suggesting the acid treatment renders all lipids extractable. This work demonstrates that acid treatment is a robust and effective cell lysis technique in a microbial lipid-based biofuel scenario and provides a baseline for further scale-up and process integration.« less
Yeast as a model for Ras signalling.

PubMed

Tisi, Renata; Belotti, Fiorella; Martegani, Enzo

2014-01-01

For centuries yeast species have been popular hosts for classical biotechnology processes, such as baking, brewing, and wine making, and more recently for recombinant proteins production, thanks to the advantages of unicellular organisms (i.e., ease of genetic manipulation and rapid growth) together with the ability to perform eukaryotic posttranslational modifications. Moreover, yeast cells have been used for few decades as a tool for identifying the genes and pathways involved in basic cellular processes such as the cell cycle, aging, and stress response. In the budding yeast S. cerevisiae the Ras/cAMP/PKA pathway is directly involved in the regulation of metabolism, cell growth, stress resistance, and proliferation in response to the availability of nutrients and in the adaptation to glucose, controlling cytosolic cAMP levels and consequently the cAMP-dependent protein kinase (PKA) activity. Moreover, Ras signalling has been identified in several pathogenic yeasts as a key controller for virulence, due to its involvement in yeast morphogenesis. Nowadays, yeasts are still useful for Ras-like proteins investigation, both as model organisms and as a test tube to study variants of heterologous Ras-like proteins.
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
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
Quantitation & Case-Study-Driven Inquiry to Enhance Yeast Fermentation Studies

ERIC Educational Resources Information Center

Grammer, Robert T.

2012-01-01

We propose a procedure for the assay of fermentation in yeast in microcentrifuge tubes that is simple and rapid, permitting assay replicates, descriptive statistics, and the preparation of line graphs that indicate reproducibility. Using regression and simple derivatives to determine initial velocities, we suggest methods to compare the effects of…
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
Unexpected expansion of tRNA substrate recognition by the yeast m1G9 methyltransferase Trm10.

PubMed

Swinehart, William E; Henderson, Jeremy C; Jackman, Jane E

2013-08-01

N-1 Methylation of the nearly invariant purine residue found at position 9 of tRNA is a nucleotide modification found in multiple tRNA species throughout Eukarya and Archaea. First discovered in Saccharomyces cerevisiae, the tRNA methyltransferase Trm10 is a highly conserved protein both necessary and sufficient to catalyze all known instances of m1G9 modification in yeast. Although there are 19 unique tRNA species that contain a G at position 9 in yeast, and whose fully modified sequence is known, only 9 of these tRNA species are modified with m1G9 in wild-type cells. The elements that allow Trm10 to distinguish between structurally similar tRNA species are not known, and sequences that are shared between all substrate or all nonsubstrate tRNAs have not been identified. Here, we demonstrate that the in vitro methylation activity of yeast Trm10 is not sufficient to explain the observed pattern of modification in vivo, as additional tRNA species are substrates for Trm10 m1G9 methyltransferase activity. Similarly, overexpression of Trm10 in yeast yields m1G9 containing tRNA species that are ordinarily unmodified in vivo. Thus, yeast Trm10 has a significantly broader tRNA substrate specificity than is suggested by the observed pattern of modification in wild-type yeast. These results may shed light onto the suggested involvement of Trm10 in other pathways in other organisms, particularly in higher eukaryotes that contain up to three different genes with sequence similarity to the single TRM10 gene in yeast, and where these other enzymes have been implicated in pathways beyond tRNA processing.

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.
Novel structural features in Candida albicans hyphal glucan provide a basis for differential innate immune recognition of hyphae versus yeast.

PubMed

Lowman, Douglas W; Greene, Rachel R; Bearden, Daniel W; Kruppa, Michael D; Pottier, Max; Monteiro, Mario A; Soldatov, Dmitriy V; Ensley, Harry E; Cheng, Shih-Chin; Netea, Mihai G; Williams, David L

2014-02-07

The innate immune system differentially recognizes Candida albicans yeast and hyphae. It is not clear how the innate immune system effectively discriminates between yeast and hyphal forms of C. albicans. Glucans are major components of the fungal cell wall and key fungal pathogen-associated molecular patterns. C. albicans yeast glucan has been characterized; however, little is known about glucan structure in C. albicans hyphae. Using an extraction procedure that minimizes degradation of the native structure, we extracted glucans from C. albicans hyphal cell walls. (1)H NMR data analysis revealed that, when compared with reference (1→3,1→6) β-linked glucans and C. albicans yeast glucan, hyphal glucan has a unique cyclical or "closed chain" structure that is not found in yeast glucan. GC/MS analyses showed a high abundance of 3- and 6-linked glucose units when compared with yeast β-glucan. In addition to the expected (1→3), (1→6), and 3,6 linkages, we also identified a 2,3 linkage that has not been reported previously in C. albicans. Hyphal glucan induced robust immune responses in human peripheral blood mononuclear cells and macrophages via a Dectin-1-dependent mechanism. In contrast, C. albicans yeast glucan was a much less potent stimulus. We also demonstrated the capacity of C. albicans hyphal glucan, but not yeast glucan, to induce IL-1β processing and secretion. This finding provides important evidence for understanding the immune discrimination between colonization and invasion at the mucosal level. When taken together, these data provide a structural basis for differential innate immune recognition of C. albicans yeast versus hyphae.
Novel Structural Features in Candida albicans Hyphal Glucan Provide a Basis for Differential Innate Immune Recognition of Hyphae Versus Yeast*

PubMed Central

Lowman, Douglas W.; Greene, Rachel R.; Bearden, Daniel W.; Kruppa, Michael D.; Pottier, Max; Monteiro, Mario A.; Soldatov, Dmitriy V.; Ensley, Harry E.; Cheng, Shih-Chin; Netea, Mihai G.; Williams, David L.

2014-01-01

The innate immune system differentially recognizes Candida albicans yeast and hyphae. It is not clear how the innate immune system effectively discriminates between yeast and hyphal forms of C. albicans. Glucans are major components of the fungal cell wall and key fungal pathogen-associated molecular patterns. C. albicans yeast glucan has been characterized; however, little is known about glucan structure in C. albicans hyphae. Using an extraction procedure that minimizes degradation of the native structure, we extracted glucans from C. albicans hyphal cell walls. 1H NMR data analysis revealed that, when compared with reference (1→3,1→6) β-linked glucans and C. albicans yeast glucan, hyphal glucan has a unique cyclical or “closed chain” structure that is not found in yeast glucan. GC/MS analyses showed a high abundance of 3- and 6-linked glucose units when compared with yeast β-glucan. In addition to the expected (1→3), (1→6), and 3,6 linkages, we also identified a 2,3 linkage that has not been reported previously in C. albicans. Hyphal glucan induced robust immune responses in human peripheral blood mononuclear cells and macrophages via a Dectin-1-dependent mechanism. In contrast, C. albicans yeast glucan was a much less potent stimulus. We also demonstrated the capacity of C. albicans hyphal glucan, but not yeast glucan, to induce IL-1β processing and secretion. This finding provides important evidence for understanding the immune discrimination between colonization and invasion at the mucosal level. When taken together, these data provide a structural basis for differential innate immune recognition of C. albicans yeast versus hyphae. PMID:24344127
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
Genomic evolution of the ascomycetous yeasts

USDA-ARS?s Scientific Manuscript database

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...
A systems-level approach for metabolic engineering of yeast cell factories.

PubMed

Kim, Il-Kwon; Roldão, António; Siewers, Verena; Nielsen, Jens

2012-03-01

The generation of novel yeast cell factories for production of high-value industrial biotechnological products relies on three metabolic engineering principles: design, construction, and analysis. In the last two decades, strong efforts have been put on developing faster and more efficient strategies and/or technologies for each one of these principles. For design and construction, three major strategies are described in this review: (1) rational metabolic engineering; (2) inverse metabolic engineering; and (3) evolutionary strategies. Independent of the selected strategy, the process of designing yeast strains involves five decision points: (1) choice of product, (2) choice of chassis, (3) identification of target genes, (4) regulating the expression level of target genes, and (5) network balancing of the target genes. At the construction level, several molecular biology tools have been developed through the concept of synthetic biology and applied for the generation of novel, engineered yeast strains. For comprehensive and quantitative analysis of constructed strains, systems biology tools are commonly used and using a multi-omics approach. Key information about the biological system can be revealed, for example, identification of genetic regulatory mechanisms and competitive pathways, thereby assisting the in silico design of metabolic engineering strategies for improving strain performance. Examples on how systems and synthetic biology brought yeast metabolic engineering closer to industrial biotechnology are described in this review, and these examples should demonstrate the potential of a systems-level approach for fast and efficient generation of yeast cell factories. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
XRN1 Is a Species-Specific Virus Restriction Factor in Yeasts

PubMed Central

Rowley, Paul A.; Ho, Brandon; Bushong, Sarah; Johnson, Arlen; Sawyer, Sara L.

2016-01-01

In eukaryotes, the degradation of cellular mRNAs is accomplished by Xrn1 and the cytoplasmic exosome. Because viral RNAs often lack canonical caps or poly-A tails, they can also be vulnerable to degradation by these host exonucleases. Yeast lack sophisticated mechanisms of innate and adaptive immunity, but do use RNA degradation as an antiviral defense mechanism. We find a highly refined, species-specific relationship between Xrn1p and the “L-A” totiviruses of different Saccharomyces yeast species. We show that the gene XRN1 has evolved rapidly under positive natural selection in Saccharomyces yeast, resulting in high levels of Xrn1p protein sequence divergence from one yeast species to the next. We also show that these sequence differences translate to differential interactions with the L-A virus, where Xrn1p from S. cerevisiae is most efficient at controlling the L-A virus that chronically infects S. cerevisiae, and Xrn1p from S. kudriavzevii is most efficient at controlling the L-A-like virus that we have discovered within S. kudriavzevii. All Xrn1p orthologs are equivalent in their interaction with another virus-like parasite, the Ty1 retrotransposon. Thus, Xrn1p appears to co-evolve with totiviruses to maintain its potent antiviral activity and limit viral propagation in Saccharomyces yeasts. We demonstrate that Xrn1p physically interacts with the Gag protein encoded by the L-A virus, suggesting a host-virus interaction that is more complicated than just Xrn1p-mediated nucleolytic digestion of viral RNAs. PMID:27711183
Phosphatidic acid synthesis in yeast

PubMed Central

Kuhn, N. J.; Lynen, F.

1965-01-01

1. The presence of palmitoyl-CoA–l-glycerol 1-phosphate palmitoyltransferase (EC2.3.1.15) has been demonstrated in a particulate fraction of baker's yeast. 2. The enzyme has been characterized, and its activity studied as a function of pH and concentration of substrates. 3. Inhibition by thiol poisons and protection by acyl-CoA have been used to obtain information on the active site. 4. By various methods of supplying acyl radicals, the species `palmitoyl-CoA' has been shown to be the true acyl donor to the transferase. PMID:14342236
TdKT, a new killer toxin produced by Torulaspora delbrueckii effective against wine spoilage yeasts.

PubMed

Villalba, María Leticia; Susana Sáez, Julieta; Del Monaco, Silvana; Lopes, Christian Ariel; Sangorrín, Marcela Paula

2016-01-18

Microbiological spoilage is a major concern throughout the wine industry, and control tools are limited. This paper addresses the identification and partial characterization of a new killer toxin from Torulaspora delbrueckii with potential biocontrol activity of Brettanomyces bruxellensis, Pichia guilliermondii, Pichia manshurica and Pichia membranifaciens wine spoilage. A panel of 18 different wine strains of T. delbrueckii killer yeasts was analysed, and the strain T. delbrueckii NPCC 1033 (TdKT producer) showed a significant inhibitory effect on the growth of all different spoilage yeasts evaluated. The TdKT toxin was then subjected to a partial biochemical characterization. Its estimated molecular weight was N30 kDa and it showed glucanase and chitinase enzymatic activities. The killer activity was stable between pH 4.2 and 4.8 and inactivated at temperature above 40 °C. Pustulan and chitin — but not other cell wall polysaccharides — prevented sensitive yeast cells from being killed by TdKT, suggesting that those may be the first toxin targets in the cell wall. TdKT provoked an increase in necrosis cell death after 3 h treatment and apoptotic cell death after 24 h showing time dependence in its mechanisms of action. Killer toxin extracts were active at oenological conditions, confirming their potential use as a biocontrol tool in winemaking.
The yeast Hsp70 homolog Ssb: a chaperone for general de novo protein folding and a nanny for specific intrinsically disordered protein domains.

PubMed

Hübscher, Volker; Mudholkar, Kaivalya; Rospert, Sabine

2017-02-01

Activation of the heterotrimeric kinase SNF1 via phosphorylation of a specific residue within the α subunit is essential for the release from glucose repression in the yeast Saccharomyces cerevisiae. When glucose is available, SNF1 is maintained in the dephosphorylated, inactive state by the phosphatase Glc7-Reg1. Recent findings suggest that Bmh and Ssb combine their unique client-binding properties to interact with the regulatory region of the SNF1 α subunit and by that stabilize a conformation of SNF1, which is accessible for Glc7-Reg1-dependent dephosphorylation. Together, the 14-3-3 protein Bmh and the Hsp70 homolog Ssb comprise a novel chaperone module, which is required to maintain proper glucose repression in the yeast S. cerevisiae.
Version 6 of the consensus yeast metabolic network refines biochemical coverage and improves model performance

PubMed Central

Heavner, Benjamin D.; Smallbone, Kieran; Price, Nathan D.; Walker, Larry P.

2013-01-01

Updates to maintain a state-of-the art reconstruction of the yeast metabolic network are essential to reflect our understanding of yeast metabolism and functional organization, to eliminate any inaccuracies identified in earlier iterations, to improve predictive accuracy and to continue to expand into novel subsystems to extend the comprehensiveness of the model. Here, we present version 6 of the consensus yeast metabolic network (Yeast 6) as an update to the community effort to computationally reconstruct the genome-scale metabolic network of Saccharomyces cerevisiae S288c. Yeast 6 comprises 1458 metabolites participating in 1888 reactions, which are annotated with 900 yeast genes encoding the catalyzing enzymes. Compared with Yeast 5, Yeast 6 demonstrates improved sensitivity, specificity and positive and negative predictive values for predicting gene essentiality in glucose-limited aerobic conditions when analyzed with flux balance analysis. Additionally, Yeast 6 improves the accuracy of predicting the likelihood that a mutation will cause auxotrophy. The network reconstruction is available as a Systems Biology Markup Language (SBML) file enriched with Minimium Information Requested in the Annotation of Biochemical Models (MIRIAM)-compliant annotations. Small- and macromolecules in the network are referenced to authoritative databases such as Uniprot or ChEBI. Molecules and reactions are also annotated with appropriate publications that contain supporting evidence. Yeast 6 is freely available at http://yeast.sf.net/ as three separate SBML files: a model using the SBML level 3 Flux Balance Constraint package, a model compatible with the MATLAB® COBRA Toolbox for backward compatibility and a reconstruction containing only reactions for which there is experimental evidence (without the non-biological reactions necessary for simulating growth). Database URL: http://yeast.sf.net/ PMID:23935056
Functional mapping of yeast genomes by saturated transposition

PubMed Central

Michel, Agnès H; Hatakeyama, Riko; Kimmig, Philipp; Arter, Meret; Peter, Matthias; Matos, Joao; De Virgilio, Claudio; Kornmann, Benoît

2017-01-01

Yeast is a powerful model for systems genetics. We present a versatile, time- and labor-efficient method to functionally explore the Saccharomyces cerevisiae genome using saturated transposon mutagenesis coupled to high-throughput sequencing. SAturated Transposon Analysis in Yeast (SATAY) allows one-step mapping of all genetic loci in which transposons can insert without disrupting essential functions. SATAY is particularly suited to discover loci important for growth under various conditions. SATAY (1) reveals positive and negative genetic interactions in single and multiple mutant strains, (2) can identify drug targets, (3) detects not only essential genes, but also essential protein domains, (4) generates both null and other informative alleles. In a SATAY screen for rapamycin-resistant mutants, we identify Pib2 (PhosphoInositide-Binding 2) as a master regulator of TORC1. We describe two antagonistic TORC1-activating and -inhibiting activities located on opposite ends of Pib2. Thus, SATAY allows to easily explore the yeast genome at unprecedented resolution and throughput. DOI: http://dx.doi.org/10.7554/eLife.23570.001 PMID:28481201
Dynamic Changes in Yeast Phosphatase Families Allow for Specialization in Phosphate and Thiamine Starvation.

PubMed

Nahas, John V; Iosue, Christine L; Shaik, Noor F; Selhorst, Kathleen; He, Bin Z; Wykoff, Dennis D

2018-05-10

Convergent evolution is often due to selective pressures generating a similar phenotype. We observe relatively recent duplications in a spectrum of Saccharomycetaceae yeast species resulting in multiple phosphatases that are regulated by different nutrient conditions - thiamine and phosphate starvation. This specialization is both transcriptional and at the level of phosphatase substrate specificity. In Candida glabrata , loss of the ancestral phosphatase family was compensated by the co-option of a different histidine phosphatase family with three paralogs. Using RNA-seq and functional assays, we identify one of these paralogs, CgPMU3 , as a thiamine phosphatase. We further determine that the 81% identical paralog CgPMU2 does not encode thiamine phosphatase activity; however, both are capable of cleaving the phosphatase substrate, 1-napthyl-phosphate. We functionally demonstrate that members of this family evolved novel enzymatic functions for phosphate and thiamine starvation, and are regulated transcriptionally by either nutrient condition, and observe similar trends in other yeast species. This independent, parallel evolution involving two different families of histidine phosphatases suggests that there were likely similar selective pressures on multiple yeast species to recycle thiamine and phosphate. In this work, we focused on duplication and specialization, but there is also repeated loss of phosphatases, indicating that the expansion and contraction of the phosphatase family is dynamic in many Ascomycetes. The dynamic evolution of the phosphatase gene families is perhaps just one example of how gene duplication, co-option, and transcriptional and functional specialization together allow species to adapt to their environment with existing genetic resources. Copyright © 2018, G3: Genes, Genomes, Genetics.
Comparative genomics of biotechnologically important yeasts

USDA-ARS?s Scientific Manuscript database

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...
A new series of yeast shuttle vectors for the recovery and identification of multiple plasmids from Saccharomyces cerevisiae.

PubMed

Frazer, LilyAnn Novak; O'Keefe, Raymond T

2007-09-01

The availability of Saccharomyces cerevisiae yeast strains with multiple auxotrophic markers allows the stable introduction and selection of more than one yeast shuttle vector containing marker genes that complement the auxotrophic markers. In certain experimental situations there is a need to recover more than one shuttle vector from yeast. To facilitate the recovery and identification of multiple plasmids from S. cerevisiae, we have constructed a series of plasmids based on the pRS series of yeast shuttle vectors. Bacterial antibiotic resistance genes to chloramphenicol, kanamycin and zeocin have been combined with the yeast centromere sequence (CEN6), the autonomously replicating sequence (ARSH4) and one of the four yeast selectable marker genes (HIS3, TRP1, LEU2 or URA3) from the pRS series of vectors. The 12 plasmids produced differ in antibiotic resistance and yeast marker gene within the backbone of the multipurpose plasmid pBluescript II. The newly constructed vectors show similar mitotic stability to the original pRS vectors. In combination with the ampicillin-resistant pRS series of yeast shuttle vectors, these plasmids now allow the recovery and identification in bacteria of up to four different vectors from S. cerevisiae. Copyright (c) 2007 John Wiley & Sons, Ltd.
Expressed Sequence Tag Analysis of the Human Pathogen Paracoccidioides brasiliensis Yeast Phase: Identification of Putative Homologues of Candida albicans Virulence and Pathogenicity Genes

PubMed Central

Goldman, Gustavo H.; dos Reis Marques, Everaldo; Custódio Duarte Ribeiro, Diógenes; Ângelo de Souza Bernardes, Luciano; Quiapin, Andréa Carla; Vitorelli, Patrícia Marostica; Savoldi, Marcela; Semighini, Camile P.; de Oliveira, Regina C.; Nunes, Luiz R.; Travassos, Luiz R.; Puccia, Rosana; Batista, Wagner L.; Ferreira, Leslie Ecker; Moreira, Júlio C.; Bogossian, Ana Paula; Tekaia, Fredj; Nobrega, Marina Pasetto; Nobrega, Francisco G.; Goldman, Maria Helena S.

2003-01-01

Paracoccidioides brasiliensis, a thermodimorphic fungus, is the causative agent of the prevalent systemic mycosis in Latin America, paracoccidioidomycosis. We present here a survey of expressed genes in the yeast pathogenic phase of P. brasiliensis. We obtained 13,490 expressed sequence tags from both 5′ and 3′ ends. Clustering analysis yielded the partial sequences of 4,692 expressed genes that were functionally classified by similarity to known genes. We have identified several Candida albicans virulence and pathogenicity homologues in P. brasiliensis. Furthermore, we have analyzed the expression of some of these genes during the dimorphic yeast-mycelium-yeast transition by real-time quantitative reverse transcription-PCR. Clustering analysis of the mycelium-yeast transition revealed three groups: (i) RBT, hydrophobin, and isocitrate lyase; (ii) malate dehydrogenase, contigs Pb1067 and Pb1145, GPI, and alternative oxidase; and (iii) ubiquitin, delta-9-desaturase, HSP70, HSP82, and HSP104. The first two groups displayed high mRNA expression in the mycelial phase, whereas the third group showed higher mRNA expression in the yeast phase. Our results suggest the possible conservation of pathogenicity and virulence mechanisms among fungi, expand considerably gene identification in P. brasiliensis, and provide a broader basis for further progress in understanding its biological peculiarities. PMID:12582121
Metabolic gene clusters encoding the enzymes of two branches of the 3-oxoadipate pathway in the pathogenic yeast Candida albicans.

PubMed

Gérecová, Gabriela; Neboháčová, Martina; Zeman, Igor; Pryszcz, Leszek P; Tomáška, Ľubomír; Gabaldón, Toni; Nosek, Jozef

2015-05-01

The pathogenic yeast Candida albicans utilizes hydroxyderivatives of benzene via the catechol and hydroxyhydroquinone branches of the 3-oxoadipate pathway. The genetic basis and evolutionary origin of this catabolic pathway in yeasts are unknown. In this study, we identified C. albicans genes encoding the enzymes involved in the degradation of hydroxybenzenes. We found that the genes coding for core components of the 3-oxoadipate pathway are arranged into two metabolic gene clusters. Our results demonstrate that C. albicans cells cultivated in media containing hydroxybenzene substrates highly induce the transcription of these genes as well as the corresponding enzymatic activities. We also found that C. albicans cells assimilating hydroxybenzenes cope with the oxidative stress by upregulation of cellular antioxidant systems such as alternative oxidase and catalase. Moreover, we investigated the evolution of the enzymes encoded by these clusters and found that most of them share a particularly sparse phylogenetic distribution among Saccharomycotina, which is likely to have been caused by extensive gene loss. We exploited this fact to find co-evolving proteins that are suitable candidates for the missing enzymes of the pathway. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Fungal spore germination into yeast or mycelium: possible implications of dimorphism in evolution and human pathogenesis

NASA Astrophysics Data System (ADS)

Ghormade, Vandana; Deshpande, M. V.

The ability of dimorphism in fungi is conventionally regarded as a reversible change between the two vegetative forms, yeast and mycelium, in response to environmental change. A zygomycetous isolate, Benjaminiella poitrasii, exhibited yeast-mycelium transition in response to the change in temperature (37-28 °C) and decrease in glucose concentration. For the first time the presence of dimorphic response during asexual and sexual spore germination is reported under the dimorphism-triggering conditions in B. poitrasii. The zygospores germinated into budding yeast when subjected to yeast-form supporting conditions. The mycelium-form favoring conditions gave rise to true mycelium. Similarly, the asexual spores displayed a dimorphic response during germination. Our observations suggest that dimorphism is an intrinsic ability present in the vegetative, asexual, and sexual forms of the fungus. As dimorphic fungi are intermediate to the unicellular yeast and the filamentous forms, understanding of the dimorphic character could be useful to trace the evolutionary relationships among taxonomically different fungi. Moreover, the implications of spore germination during the onset of pathogenesis and in drug development for human health care are discussed.
Post-fermentative production of glutathione by baker's yeast (S. cerevisiae) in compressed and dried forms.

PubMed

Musatti, Alida; Manzoni, Matilde; Rollini, Manuela

2013-01-25

The study was aimed at investigating the best biotransformation conditions to increase intracellular glutathione (GSH) levels in samples of baker's yeast (Saccharomyces cerevisiae) employing either the commercially available compressed and dried forms. Glucose, GSH precursors amino acids, as well as other cofactors, were dissolved in a biotransformation solution and yeast cells were added (5%dcw). Two response surface central composite designs (RSCCDs) were performed in sequence: in the first step the influence of amino acid composition (cysteine, glycine, glutamic acid and serine) on GSH accumulation was investigated; once their formulation was set up, the influence of other components was studied. Initial GSH content was found 0.53 and 0.47%dcw for compressed and dried forms. GSH accumulation ability of baker's yeast in compressed form was higher at the beginning of shelf life, that is, in the first week, and a maximum of 2.04%dcw was obtained. Performance of yeast in dried form was not found satisfactory, as the maximum GSH level was 1.18%dcw. When cysteine lacks from the reaction solution, yeast cells do not accumulate GSH. With dried yeast, the highest GSH yields occurred when cysteine was set at 3 g/L, glycine and glutamic acid at least at 4 g/L, without serine. Employing compressed yeast, the highest GSH yields occurred when cysteine and glutamic acid were set at 2-3 g/L, while glycine and serine higher than 2 g/L. Results allowed to set up an optimal and feasible procedure to obtain GSH-enriched yeast biomass, with up to threefold increase with respect to initial content. Copyright © 2012 Elsevier B.V. All rights reserved.
Construction of a self-cloning sake yeast that overexpresses alcohol acetyltransferase gene by a two-step gene replacement protocol.

PubMed

Hirosawa, I; Aritomi, K; Hoshida, H; Kashiwagi, S; Nishizawa, Y; Akada, R

2004-07-01

The commercial application of genetically modified industrial microorganisms has been problematic due to public concerns. We constructed a "self-cloning" sake yeast strain that overexpresses the ATF1 gene encoding alcohol acetyltransferase, to improve the flavor profile of Japanese sake. A constitutive yeast overexpression promoter, TDH3p, derived from the glyceraldehyde-3-phosphate dehydrogenase gene from sake yeast was fused to ATF1; and the 5' upstream non-coding sequence of ATF1 was further fused to TDH3p-ATF1. The fragment was placed on a binary vector, pGG119, containing a drug-resistance marker for transformation and a counter-selection marker for excision of unwanted DNA. The plasmid was integrated into the ATF1 locus of a sake yeast strain. This integration constructed tandem repeats of ATF1 and TDH3p-ATF1 sequences, between which the plasmid was inserted. Loss of the plasmid, which occurs through homologous recombination between either the TDH3p downstream ATF1 repeats or the TDH3p upstream repeat sequences, was selected by growing transformants on counter-selective medium. Recombination between the downstream repeats led to reversion to a wild type strain, but that between the upstream repeats resulted in a strain that possessed TDH3p-ATF1 without the extraneous DNA sequences. The self-cloning TDH3p-ATF1 yeast strain produced a higher amount of isoamyl acetate. This is the first expression-controlled self-cloning industrial yeast.

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