Sample records for saccharomyces cerevisiae suggest

  1. Molecular genetic diversity of the Saccharomyces yeasts in Taiwan: Saccharomyces arboricola, Saccharomyces cerevisiae and Saccharomyces kudriavzevii.

    PubMed

    Naumov, Gennadi I; Lee, Ching-Fu; Naumova, Elena S

    2013-01-01

    Genetic hybridization, sequence and karyotypic analyses of natural Saccharomyces yeasts isolated in different regions of Taiwan revealed three biological species: Saccharomyces arboricola, Saccharomyces cerevisiae and Saccharomyces kudriavzevii. Intraspecies variability of the D1/D2 and ITS1 rDNA sequences was detected among S. cerevisiae and S. kudriavzevii isolates. According to molecular and genetic analyses, the cosmopolitan species S. cerevisiae and S. kudriavzevii contain local divergent populations in Taiwan, Malaysia and Japan. Six of the seven known Saccharomyces species are documented in East Asia: S. arboricola, S. bayanus, S. cerevisiae, S. kudriavzevii, S. mikatae, and S. paradoxus.

  2. In vitro screening of probiotic properties of Saccharomyces cerevisiae var. boulardii and food-borne Saccharomyces cerevisiae strains.

    PubMed

    van der Aa Kühle, Alis; Skovgaard, Kerstin; Jespersen, Lene

    2005-05-01

    The probiotic potential of 18 Saccharomyces cerevisiae strains used for production of foods or beverages or isolated from such, and eight strains of Saccharomyces cerevisiae var. boulardii, was investigated. All strains included were able to withstand pH 2.5 and 0.3% Oxgall. Adhesion to the nontumorigenic porcine jejunal epithelial cell line (IPEC-J2) was investigated by incorporation of 3H-methionine into the yeast cells and use of liquid scintillation counting. Only few of the food-borne S. cerevisiae strains exhibited noteworthy adhesiveness with the strongest levels of adhesion (13.6-16.8%) recorded for two isolates from blue veined cheeses. Merely 25% of the S. cerevisiae var. boulardii strains displayed good adhesive properties (16.2-28.0%). The expression of the proinflammatory cytokine IL-1alpha decreased strikingly in IPEC-J2 cells exposed to a Shiga-like toxin 2e producing Escherichia coli strain when the cells were pre- and coincubated with S. cerevisiae var. boulardii even though this yeast strain was low adhesive (5.4%), suggesting that adhesion is not a mandatory prerequisite for such a probiotic effect. A strain of S. cerevisiae isolated from West African sorghum beer exerted similar effects hence indicating that food-borne strains of S. cerevisiae may possess probiotic properties in spite of low adhesiveness.

  3. The Saccharomyces cerevisiae enolase-related regions encode proteins that are active enolases.

    PubMed

    Kornblatt, M J; Richard Albert, J; Mattie, S; Zakaib, J; Dayanandan, S; Hanic-Joyce, P J; Joyce, P B M

    2013-02-01

    In addition to two genes (ENO1 and ENO2) known to code for enolase (EC4.2.1.11), the Saccharomyces cerevisiae genome contains three enolase-related regions (ERR1, ERR2 and ERR3) which could potentially encode proteins with enolase function. Here, we show that products of these genes (Err2p and Err3p) have secondary and quaternary structures similar to those of yeast enolase (Eno1p). In addition, Err2p and Err3p can convert 2-phosphoglycerate to phosphoenolpyruvate, with kinetic parameters similar to those of Eno1p, suggesting that these proteins could function as enolases in vivo. To address this possibility, we overexpressed the ERR2 and ERR3 genes individually in a double-null yeast strain lacking ENO1 and ENO2, and showed that either ERR2 or ERR3 could complement the growth defect in this strain when cells are grown in medium with glucose as the carbon source. Taken together, these data suggest that the ERR genes in Saccharomyces cerevisiae encode a protein that could function in glycolysis as enolase. The presence of these enolase-related regions in Saccharomyces cerevisiae and their absence in other related yeasts suggests that these genes may play some unique role in Saccharomyces cerevisiae. Further experiments will be required to determine whether these functions are related to glycolysis or other cellular processes. Copyright © 2012 John Wiley & Sons, Ltd.

  4. iTRAQ-based proteome profiling of Saccharomyces cerevisiae and cryotolerant species Saccharomyces uvarum and Saccharomyces kudriavzevii during low-temperature wine fermentation.

    PubMed

    García-Ríos, Estéfani; Querol, Amparo; Guillamón, José Manuel

    2016-09-02

    Temperature is one of the most important parameters to affect the duration and rate of alcoholic fermentation and final wine quality. Some species of the Saccharomyces genus have shown better adaptation at low temperature than Saccharomyces cerevisiae, which was the case of cryotolerant yeasts Saccharomyces uvarum and Saccharomyces kudriavzevii. In an attempt to detect inter-specific metabolic differences, we characterized the proteomic landscape of these cryotolerant species grown at 12°C and 28°C, which we compared with the proteome of S. cerevisiae (poorly adapted at low temperature). Our results showed that the main differences among the proteomic profiling of the three Saccharomyces strains grown at 12°C and 28°C lay in translation, glycolysis and amino acid metabolism. Our data corroborate previous transcriptomic results, which suggest that S. kudriavzevii is better adapted to grow at low temperature as a result of enhanced more efficient translation. Fitter amino acid biosynthetic pathways can also be mechanisms that better explain biomass yield in cryotolerant strains. Yet even at low temperature, S. cerevisiae is the most fermentative competitive species. A higher concentration of glycolytic and alcoholic fermentation enzymes in the S. cerevisiae strain might explain such greater fermentation activity. Temperature is one of the main relevant environmental variables that microorganisms have to cope with and it is also a key factor in some industrial processes that involve microorganisms. However, we are still far from understanding the molecular and physiological mechanisms of adaptation at low temperatures. The results obtained in this study provided a global atlas of the proteome changes triggered by temperature in three different species of the genus Saccharomyces with different degree of cryotolerance. These results would facilitate a better understanding of mechanisms for how yeast could adapt at the low temperature of growth. Copyright © 2016

  5. Impact of oxygenation on the performance of three non-Saccharomyces yeasts in co-fermentation with Saccharomyces cerevisiae.

    PubMed

    Shekhawat, Kirti; Bauer, Florian F; Setati, Mathabatha E

    2017-03-01

    The sequential or co-inoculation of grape must with non-Saccharomyces yeast species and Saccharomyces cerevisiae wine yeast strains has recently become a common practice in winemaking. The procedure intends to enhance unique aroma and flavor profiles of wine. The extent of the impact of non-Saccharomyces strains depends on their ability to produce biomass and to remain metabolically active for a sufficiently long period. However, mixed-culture wine fermentations tend to become rapidly dominated by S. cerevisiae, reducing or eliminating the non-Saccharomyces yeast contribution. For an efficient application of these yeasts, it is therefore essential to understand the environmental factors that modulate the population dynamics of such ecosystems. Several environmental parameters have been shown to influence population dynamics, but their specific effect remains largely uncharacterized. In this study, the population dynamics in co-fermentations of S. cerevisiae and three non-Saccharomyces yeast species: Torulaspora delbrueckii, Lachancea thermotolerans, and Metschnikowia pulcherrima, was investigated as a function of oxygen availability. In all cases, oxygen availability strongly influenced population dynamics, but clear species-dependent differences were observed. Our data show that L. thermotolerans required the least oxygen, followed by T. delbrueckii and M. pulcherrima. Distinct species-specific chemical volatile profiles correlated in all cases with increased persistence of non-Saccharomyces yeasts, in particular increases in some higher alcohols and medium chain fatty acids. The results highlight the role of oxygen in regulating the succession of yeasts during wine fermentations and suggests that more stringent aeration strategies would be necessary to support the persistence of non-Saccharomyces yeasts in real must fermentations.

  6. Fatal Saccharomyces Cerevisiae Aortic Graft Infection

    NASA Technical Reports Server (NTRS)

    Meyer, Michael (Technical Monitor); Smith, Davey; Metzgar, David; Wills, Christopher; Fierer, Joshua

    2002-01-01

    Saccharomyces cerevisiae is a yeast commonly used in baking and a frequent colonizer of human mucosal surfaces. It is considered relatively nonpathogenic in immunocompetent adults. We present a case of S. cerevisiae fungemia and aortic graft infection in an immunocompetent adult. This is the first reported case of S. cerevisiue fungemia where the identity of the pathogen was confirmed by rRNA sequencing.

  7. Fatal Saccharomyces cerevisiae aortic graft infection.

    PubMed

    Smith, Davey; Metzgar, David; Wills, Christopher; Fierer, Joshua

    2002-07-01

    Saccharomyces cerevisiae is a yeast commonly used in baking and a frequent colonizer of human mucosal surfaces. It is considered relatively nonpathogenic in immunocompetent adults (J. N. Aucott, J. Fayan, H. Grossnicklas, A. Morrissey, M. M. Lederman, and R. A. Salata, Rev. Infect. Dis. 12:406-411, 1990). We present a case of S. cerevisiae fungemia and aortic graft infection in an immunocompetent adult. This is the first reported case of S. cerevisiae fungemia where the identity of the pathogen was confirmed by rRNA sequencing.

  8. Saccharomyces cerevisiae vaginitis: transmission from yeast used in baking.

    PubMed

    Nyirjesy, P; Vazquez, J A; Ufberg, D D; Sobel, J D; Boikov, D A; Buckley, H R

    1995-09-01

    To determine whether vaginitis due to Saccharomyces cerevisiae can be caused by exposure to exogenous sources of baker's yeast. Eight women with S cerevisiae vaginitis were identified from a cohort of women referred for the evaluation of chronic vaginal symptoms. In those with high-level exposure to exogenous sources of S cerevisiae, isolates from the vagina and those sources were sent in a blinded fashion for contour-clamped homogeneous electric-field electrophoresis. Four women from a cohort of approximately 750 referred patients had high-level exposures to S cerevisiae. In one of these patients, electrophoresis analysis revealed similarities between the strains isolated from her vagina, her husband's fingers, and the yeast he used in his pizza shop. Saccharomyces cerevisiae vaginitis can be the result of the inoculation of this yeast from exogenous sources.

  9. Growth of non-Saccharomyces yeasts affects nutrient availability for Saccharomyces cerevisiae during wine fermentation.

    PubMed

    Medina, Karina; Boido, Eduardo; Dellacassa, Eduardo; Carrau, Francisco

    2012-07-02

    Yeast produces numerous secondary metabolites during fermentation that impact final wine quality. Although it is widely recognized that growth of diverse non-Saccharomyces (NS) yeast can positively affect flavor complexity during Saccharomyces cerevisiae wine fermentation, the inability to control spontaneous or co-fermentation processes by NS yeast has restricted their use in winemaking. We selected two NS yeasts from our Uruguayan native collection to study NS-S. cerevisiae interactions during wine fermentation. The selected strains of Hanseniaspora vineae and Metschnikowia pulcherrima had different yeast assimilable nitrogen consumption profiles and had different effects on S. cerevisiae fermentation and growth kinetics. Studies in which we varied inoculum size and using either simultaneous or sequential inoculation of NS yeast and S. cerevisiae suggested that competition for nutrients had a significant effect on fermentation kinetics. Sluggish fermentations were more pronounced when S. cerevisiae was inoculated 24h after the initial stage of fermentation with a NS strain compared to co-inoculation. Monitoring strain populations using differential WL nutrient agar medium and fermentation kinetics of mixed cultures allowed for a better understanding of strain interactions and nutrient addition effects. Limitation of nutrient availability for S. cerevisiae was shown to result in stuck fermentations as well as to reduce sensory desirability of the resulting wine. Addition of diammonium phosphate (DAP) and a vitamin mix to a defined medium allowed for a comparison of nutrient competition between strains. Addition of DAP and the vitamin mix was most effective in preventing stuck fermentations. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. 21 CFR 866.5785 - Anti-Saccharomyces cerevisiae (S. cerevisiae) antibody (ASCA) test systems.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) antibody (ASCA) test systems. 866.5785 Section 866.5785 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunological Test Systems § 866.5785 Anti-Saccharomyces cerevisiae (S. cerevisiae) antibody (ASCA) test systems...

  11. Intracellular Signal Triggered by Cholera Toxin in Saccharomyces boulardii and Saccharomyces cerevisiae

    PubMed Central

    Brandão, Rogelio L.; Castro, Ieso M.; Bambirra, Eduardo A.; Amaral, Sheila C.; Fietto, Luciano G.; Tropia, Maria José M.; Neves, Maria José; Dos Santos, Raquel G.; Gomes, Newton C. M.; Nicoli, Jacques R.

    1998-01-01

    As is the case for Saccharomyces boulardii, Saccharomyces cerevisiae W303 protects Fisher rats against cholera toxin (CT). The addition of glucose or dinitrophenol to cells of S. boulardii grown on a nonfermentable carbon source activated trehalase in a manner similar to that observed for S. cerevisiae. The addition of CT to the same cells also resulted in trehalase activation. Experiments performed separately on the A and B subunits of CT showed that both are necessary for activation. Similarly, the addition of CT but not of its separate subunits led to a cyclic AMP (cAMP) signal in both S. boulardii and S. cerevisiae. These data suggest that trehalase stimulation by CT probably occurred through the cAMP-mediated protein phosphorylation cascade. The requirement of CT subunit B for both the cAMP signal and trehalase activation indicates the presence of a specific receptor on the yeasts able to bind to the toxin, a situation similar to that observed for mammalian cells. This hypothesis was reinforced by experiments with 125I-labeled CT showing specific binding of the toxin to yeast cells. The adhesion of CT to a receptor on the yeast surface through the B subunit and internalization of the A subunit (necessary for the cAMP signal and trehalase activation) could be one more mechanism explaining protection against the toxin observed for rats treated with yeasts. PMID:9464394

  12. Saccharomyces cerevisiae and non-Saccharomyces yeasts in grape varieties of the São Francisco Valley

    PubMed Central

    de Ponzzes-Gomes, Camila M.P.B.S.; de Mélo, Dângelly L.F.M.; Santana, Caroline A.; Pereira, Giuliano E.; Mendonça, Michelle O.C.; Gomes, Fátima C.O.; Oliveira, Evelyn S.; Barbosa, Antonio M.; Trindade, Rita C.; Rosa, Carlos A.

    2014-01-01

    The aims of this work was to characterise indigenous Saccharomyces cerevisiae strains in the naturally fermented juice of grape varieties Cabernet Sauvignon, Grenache, Tempranillo, Sauvignon Blanc and Verdejo used in the São Francisco River Valley, northeastern Brazil. In this study, 155 S. cerevisiae and 60 non-Saccharomyces yeasts were isolated and identified using physiological tests and sequencing of the D1/D2 domains of the large subunit of the rRNA gene. Among the non-Saccharomyces species, Rhodotorula mucilaginosa was the most common species, followed by Pichia kudriavzevii, Candida parapsilosis, Meyerozyma guilliermondii, Wickerhamomyces anomalus, Kloeckera apis, P. manshurica, C. orthopsilosis and C. zemplinina. The population counts of these yeasts ranged among 1.0 to 19 × 105 cfu/mL. A total of 155 isolates of S. cerevisiae were compared by mitochondrial DNA restriction analysis, and five molecular mitochondrial DNA restriction profiles were detected. Indigenous strains of S. cerevisiae isolated from grapes of the São Francisco Valley can be further tested as potential starters for wine production. PMID:25242923

  13. Saccharomyces cerevisiae and non-Saccharomyces yeasts in grape varieties of the São Francisco Valley.

    PubMed

    de Ponzzes-Gomes, Camila M P B S; de Mélo, Dângelly L F M; Santana, Caroline A; Pereira, Giuliano E; Mendonça, Michelle O C; Gomes, Fátima C O; Oliveira, Evelyn S; Barbosa, Antonio M; Trindade, Rita C; Rosa, Carlos A

    2014-01-01

    The aims of this work was to characterise indigenous Saccharomyces cerevisiae strains in the naturally fermented juice of grape varieties Cabernet Sauvignon, Grenache, Tempranillo, Sauvignon Blanc and Verdejo used in the São Francisco River Valley, northeastern Brazil. In this study, 155 S. cerevisiae and 60 non-Saccharomyces yeasts were isolated and identified using physiological tests and sequencing of the D1/D2 domains of the large subunit of the rRNA gene. Among the non-Saccharomyces species, Rhodotorula mucilaginosa was the most common species, followed by Pichia kudriavzevii, Candida parapsilosis, Meyerozyma guilliermondii, Wickerhamomyces anomalus, Kloeckera apis, P. manshurica, C. orthopsilosis and C. zemplinina. The population counts of these yeasts ranged among 1.0 to 19 × 10(5) cfu/mL. A total of 155 isolates of S. cerevisiae were compared by mitochondrial DNA restriction analysis, and five molecular mitochondrial DNA restriction profiles were detected. Indigenous strains of S. cerevisiae isolated from grapes of the São Francisco Valley can be further tested as potential starters for wine production.

  14. 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.

  15. Saccharomyces cerevisiae: a nomadic yeast with no niche?

    PubMed

    Goddard, Matthew R; Greig, Duncan

    2015-05-01

    Different species are usually thought to have specific adaptations, which allow them to occupy different ecological niches. But recent neutral ecology theory suggests that species diversity can simply be the result of random sampling, due to finite population sizes and limited dispersal. Neutral models predict that species are not necessarily adapted to specific niches, but are functionally equivalent across a range of habitats. Here, we evaluate the ecology of Saccharomyces cerevisiae, one of the most important microbial species in human history. The artificial collection, concentration and fermentation of large volumes of fruit for alcohol production produce an environment in which S. cerevisiae thrives, and therefore it is assumed that fruit is the ecological niche that S. cerevisiae inhabits and has adapted to. We find very little direct evidence that S. cerevisiae is adapted to fruit, or indeed to any other specific niche. We propose instead a neutral nomad model for S. cerevisiae, which we believe should be used as the starting hypothesis in attempting to unravel the ecology of this important microbe. © FEMS 2015.

  16. [Saccharomyces cerevisiae infections].

    PubMed

    Souza Goebel, Cristine; de Mattos Oliveira, Flávio; Severo, Luiz Carlos

    2013-01-01

    Saccharomyces cerevisiae is an ubiquitous yeast widely used in industry and it is also a common colonizer of the human mucosae. However, the incidence of invasive infection by these fungi has significantly increased in the last decades. To evaluate the infection by S. cerevisiae in a hospital in southern Brazil during a period of 10 years (2000-2010). Review of medical records of patients infected by this fungus. In this period, 6 patients were found to be infected by S. cerevisiae. The age range of the patients was from 10 years to 84. Urine, blood, ascitic fluid, peritoneal dialysis fluid, and esophageal biopsy samples were analyzed. The predisposing factors were cancer, transplant, surgical procedures, renal failure, use of venous catheters, mechanical ventilation, hospitalization in Intensive Care Unit, diabetes mellitus, chemotherapy, corticosteroid use, and parenteral nutrition. Amphotericin B and fluconazole were the treatments of choice. Three of the patients died and the other 3 were discharged from hospital. We must take special precautions in emerging infections, especially when there are predisposing conditions such as immunosuppression or patients with serious illnesses. The rapid and specific diagnosis of S. cerevisiae infections is important for therapeutic decision. Furthermore, epidemiological and efficacy studies of antifungal agents are necessary for a better therapeutic approach. Copyright © 2012 Revista Iberoamericana de Micología. Published by Elsevier Espana. All rights reserved.

  17. 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

  18. 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.

  19. Divergence in wine characteristics produced by wild and domesticated strains of Saccharomyces cerevisiae

    PubMed Central

    Hyma, Katie E; Saerens, Sofie M; Verstrepen, Kevin J; Fay, Justin C

    2011-01-01

    The budding yeast Saccharomyces cerevisiae is the primary species used by wine makers to convert sugar into alcohol during wine fermentation. Saccharomyces cerevisiae is found in vineyards, but is also found in association with oak trees and other natural sources. Although wild strains of S. cerevisiae as well as other Saccharomyces species are also capable of wine fermentation, a genetically distinct group of S. cerevisiae strains is primarily used to produce wine, consistent with the idea that wine making strains have been domesticated for wine production. In this study, we demonstrate that humans can distinguish between wines produced using wine strains and wild strains of S. cerevisiae as well as its sibling species, Saccharomyces paradoxus. Wine strains produced wine with fruity and floral characteristics, whereas wild strains produced wine with earthy and sulfurous characteristics. The differences that we observe between wine and wild strains provides further evidence that wine strains have evolved phenotypes that are distinct from their wild ancestors and relevant to their use in wine production. PMID:22093681

  20. Metabolic Engineering of Saccharomyces cerevisiae

    PubMed Central

    Ostergaard, Simon; Olsson, Lisbeth; Nielsen, Jens

    2000-01-01

    Comprehensive knowledge regarding Saccharomyces cerevisiae has accumulated over time, and today S. cerevisiae serves as a widley used biotechnological production organism as well as a eukaryotic model system. The high transformation efficiency, in addition to the availability of the complete yeast genome sequence, has facilitated genetic manipulation of this microorganism, and new approaches are constantly being taken to metabolicially engineer this organism in order to suit specific needs. In this paper, strategies and concepts for metabolic engineering are discussed and several examples based upon selected studies involving S. cerevisiae are reviewed. The many different studies of metabolic engineering using this organism illustrate all the categories of this multidisciplinary field: extension of substrate range, improvements of producitivity and yield, elimination of byproduct formation, improvement of process performance, improvements of cellular properties, and extension of product range including heterologous protein production. PMID:10704473

  1. Saccharomyces cerevisiae fungemia: an emerging infectious disease.

    PubMed

    Muñoz, Patricia; Bouza, Emilio; Cuenca-Estrella, Manuel; Eiros, Jose María; Pérez, María Jesús; Sánchez-Somolinos, Mar; Rincón, Cristina; Hortal, Javier; Peláez, Teresa

    2005-06-01

    Saccharomyces cerevisiae is well known in the baking and brewing industry and is also used as a probiotic in humans. However, it is a very uncommon cause of infection in humans. During the period of 15-30 April 2003, we found 3 patients with S. cerevisiae fungemia in an intensive care unit (ICU). An epidemiological study was performed, and the medical records for all patients who were in the unit during the second half of April were assessed. The only identified risk factor for S. cerevisiae infection was treatment with a probiotic containing Saccharomyces boulardii (Ultralevura; Bristol-Myers Squibb). This probiotic is used in Europe for the treatment and prevention of Clostridium difficile-associated diarrhea. The 3 patients received the product via nasograstric tube for a mean duration of 8.5 days before the culture result was positive, whereas only 2 of 41 control subjects had received it. Surveillance cultures for the control patients admitted at the same time did not reveal any carriers of the yeast. Strains from the probiotic capsules and the clinical isolates were identified as S. cerevisiae, with identical DNA fingerprinting. Discontinuation of use of the product in the unit stopped the outbreak of infection. A review of the literature identified another 57 cases of S. cerevisiae fungemia. Overall, 60% of these patients were in the ICU, and 71% were receiving enteral or parenteral nutrition. Use of probiotics was detected in 26 patients, and 17 patients died. Use of S. cerevisiae probiotics should be carefully reassessed, particularly in immunosuppressed or critically ill patients.

  2. Gains and Losses of Transcription Factor Binding Sites in Saccharomyces cerevisiae and Saccharomyces paradoxus

    PubMed Central

    Schaefke, Bernhard; Wang, Tzi-Yuan; Wang, Chuen-Yi; Li, Wen-Hsiung

    2015-01-01

    Gene expression evolution occurs through changes in cis- or trans-regulatory elements or both. Interactions between transcription factors (TFs) and their binding sites (TFBSs) constitute one of the most important points where these two regulatory components intersect. In this study, we investigated the evolution of TFBSs in the promoter regions of different Saccharomyces strains and species. We divided the promoter of a gene into the proximal region and the distal region, which are defined, respectively, as the 200-bp region upstream of the transcription starting site and as the 200-bp region upstream of the proximal region. We found that the predicted TFBSs in the proximal promoter regions tend to be evolutionarily more conserved than those in the distal promoter regions. Additionally, Saccharomyces cerevisiae strains used in the fermentation of alcoholic drinks have experienced more TFBS losses than gains compared with strains from other environments (wild strains, laboratory strains, and clinical strains). We also showed that differences in TFBSs correlate with the cis component of gene expression evolution between species (comparing S. cerevisiae and its sister species Saccharomyces paradoxus) and within species (comparing two closely related S. cerevisiae strains). PMID:26220934

  3. Saccharomyces cerevisiae engineered for xylose metabolism exhibits a respiratory response

    Treesearch

    Yong-Su Jin; Jose M. Laplaza; Thomas W. Jeffries

    2004-01-01

    Native strains of Saccharomyces cerevisiae do not assimilate xylose. S. cerevisiae engineered for D-xylose utilization through the heterologous expression of genes for aldose reductase ( XYL1), xylitol dehydrogenase (XYL2), and D-xylulokinase ( XYL3 or XKS1) produce only limited amounts of ethanol in xylose medium. In recombinant S. cerevisiae expressing XYL1, XYL2,...

  4. Water treatment process and system for metals removal using Saccharomyces cerevisiae

    DOEpatents

    Krauter, Paula A. W.; Krauter, Gordon W.

    2002-01-01

    A process and a system for removal of metals from ground water or from soil by bioreducing or bioaccumulating the metals using metal tolerant microorganisms Saccharomyces cerevisiae. Saccharomyces cerevisiae is tolerant to the metals, able to bioreduce the metals to the less toxic state and to accumulate them. The process and the system is useful for removal or substantial reduction of levels of chromium, molybdenum, cobalt, zinc, nickel, calcium, strontium, mercury and copper in water.

  5. Mechanisms of Ethanol Tolerance in Saccharomyces cerevisiae

    USDA-ARS?s Scientific Manuscript database

    Saccharomyces cerevisiae is a superb ethanol producer, yet is also sensitive to higher ethanol concentrations especially under high gravity or very high gravity fermentation conditions. Ethanol tolerance is associated with interplay of complex networks at the genome level. Although significant eff...

  6. Creation of a synthetic xylose-inducible promoter for Saccharomyces cerevisiae

    USDA-ARS?s Scientific Manuscript database

    Saccharomyces cerevisiae is currently used to produce ethanol from glucose, but it cannot utilize five-carbon sugars contained in the hemicellulose component of biomass feedstocks. S. cerevisiae strains engineered for xylose fermentation have been made using constitutive promoters to express the req...

  7. Immunoelectron Microscopy of Cryofixed Freeze-Substituted Yeast Saccharomyces cerevisiae.

    PubMed

    Fišerová, Jindřiška; Richardson, Christine; Goldberg, Martin W

    2016-01-01

    Immunolabeling electron microscopy is a challenging technique with demands for perfect ultrastructural and antigen preservation. High-pressure freezing offers an excellent way to fix cellular structure. However, its use for immunolabeling has remained limited because of the low frequency of labeling due to loss of protein antigenicity or accessibility. Here we present a protocol for immunogold labeling of the yeast Saccharomyces cerevisiae that gives specific and multiple labeling while keeping the finest structural details. We use the protocol to reveal the organization of individual nuclear pore complex proteins and the position of transport factors in the yeast Saccharomyces cerevisiae in relation to actual transport events.

  8. Tangential Ultrafiltration of Aqueous "Saccharomyces Cerevisiae" Suspensions

    ERIC Educational Resources Information Center

    Silva, Carlos M.; Neves, Patricia S.; Da Silva, Francisco A.; Xavier, Ana M. R. B.; Eusebio, M. F. J.

    2008-01-01

    Experimental work on ultrafiltration is presented to illustrate the practical and theoretical principles of this separation technique. The laboratory exercise comprises experiments with pure water and with aqueous "Saccharomyces cerevisiae" (from commercial Baker's yeast) suspensions. With this work students detect the characteristic phenomena…

  9. Gains and Losses of Transcription Factor Binding Sites in Saccharomyces cerevisiae and Saccharomyces paradoxus.

    PubMed

    Schaefke, Bernhard; Wang, Tzi-Yuan; Wang, Chuen-Yi; Li, Wen-Hsiung

    2015-07-27

    Gene expression evolution occurs through changes in cis- or trans-regulatory elements or both. Interactions between transcription factors (TFs) and their binding sites (TFBSs) constitute one of the most important points where these two regulatory components intersect. In this study, we investigated the evolution of TFBSs in the promoter regions of different Saccharomyces strains and species. We divided the promoter of a gene into the proximal region and the distal region, which are defined, respectively, as the 200-bp region upstream of the transcription starting site and as the 200-bp region upstream of the proximal region. We found that the predicted TFBSs in the proximal promoter regions tend to be evolutionarily more conserved than those in the distal promoter regions. Additionally, Saccharomyces cerevisiae strains used in the fermentation of alcoholic drinks have experienced more TFBS losses than gains compared with strains from other environments (wild strains, laboratory strains, and clinical strains). We also showed that differences in TFBSs correlate with the cis component of gene expression evolution between species (comparing S. cerevisiae and its sister species Saccharomyces paradoxus) and within species (comparing two closely related S. cerevisiae strains). © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  10. Saccharomyces cerevisiae Shuttle vectors.

    PubMed

    Gnügge, Robert; Rudolf, Fabian

    2017-05-01

    Yeast shuttle vectors are indispensable tools in yeast research. They enable cloning of defined DNA sequences in Escherichia coli and their direct transfer into Saccharomyces cerevisiae cells. There are three types of commonly used yeast shuttle vectors: centromeric plasmids, episomal plasmids and integrating plasmids. In this review, we discuss the different plasmid systems and their characteristic features. We focus on their segregational stability and copy number and indicate how to modify these properties. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  11. Enological characterization of Spanish Saccharomyces kudriavzevii strains, one of the closest relatives to parental strains of winemaking and brewing Saccharomyces cerevisiae × S. kudriavzevii hybrids.

    PubMed

    Peris, D; Pérez-Través, L; Belloch, C; Querol, A

    2016-02-01

    Wine fermentation and innovation have focused mostly on Saccharomyces cerevisiae strains. However, recent studies have shown that other Saccharomyces species can also be involved in wine fermentation or are useful for wine bouquet, such as Saccharomyces uvarum and Saccharomyces paradoxus. Many interspecies hybrids have also been isolated from wine fermentation, such as S. cerevisiae × Saccharomyces kudriavzevii hybrids. In this study, we explored the genetic diversity and fermentation performance of Spanish S. kudriavzevii strains, which we compared to other S. kudriavzevii strains. Fermentations of red and white grape musts were performed, and the phenotypic differences between Spanish S. kudriavzevii strains under different temperature conditions were examined. An ANOVA analysis suggested striking similarity between strains for glycerol and ethanol production, although a high diversity of aromatic profiles among fermentations was found. The sources of these phenotypic differences are not well understood and require further investigation. Although the Spanish S. kudriavzevii strains showed desirable properties, particularly must fermentations, the quality of their wines was no better than those produced with a commercial S. cerevisiae. We suggest hybridization or directed evolution as methods to improve and innovate wine. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Stoichiometric network constraints on xylose metabolism by recombinant Saccharomyces cerevisiae

    Treesearch

    Yong-Su Jin; Thomas W. Jeffries

    2004-01-01

    Metabolic pathway engineering is constrained by the thermodynamic and stoichiometric feasibility of enzymatic activities of introduced genes. Engineering of xylose metabolism in Saccharomyces cerevisiae has focused on introducing genes for the initial xylose assimilation steps from Pichia stipitis, a xylose-fermenting yeast, into S. cerevisiae, a yeast raditionally...

  13. Influence of temperature and nutrient strength on the susceptibility of Saccharomyces cerevisiae to heavy metals

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

    Hsu, T.; Lee, L.W.; Chang, T.H.

    1992-09-01

    Saccharomyces cerevisiae is not only a key microorganism in brewing or fermentation processes, it has also been employed for monitoring aquatic pollutants. The major advantage of using Saccharomyces cerevisiae as a bioassay system is that this yeast can be easily obtained as dry pellets from commercial sources at low cost. In addition to its economical aspect, Saccharomyces cerevisiae, like other microorganisms, is easy to handle, grows rapidly, and provides a large number of homogeneous individuals for utilization in toxicity tests. Although cell growth, cell viability, electron transport and mitochondrial respiration of Saccharomyces cerevisiaes have all been selected as parameters formore » toxicity assessment, measuring cell growth by absorbance is by farm the most convenient and rapid method when large amounts of water samples are to be tested. Mochida et al. (1988), however, reported that Saccharomyces cerevisiae was five to ten times less sensitive than cell culture systems to cadmium, mercury and nickel, when cell growth of both systems was monitored. This relative insensitivity to heavy metals might handicap the practical use of this yeast strain for bioassays. Since previous studies indicated that the susceptibility of microorganisms to environmental toxicants can be influenced by incubation temperature and nutrient strength, we attempted to examine the effect of incubation temperature and nutrient strength on the susceptibility of Saccharomyces cerevisiae to heavy metals in order to obtain the optimum bioassay sensitivity. In this study, we used cadmium and mercury as model toxicants. 9 refs., 2 figs., 1 tab.« less

  14. Invasive Saccharomyces cerevisiae infection: a friend turning foe?

    PubMed

    Pillai, Unnikrishnan; Devasahayam, Joe; Kurup, Aparna Narayana; Lacasse, Alexandre

    2014-11-01

    We report a very rare case of acute pyelonephritis in a 51-year-old female with a history of chronic kidney disease (CKD) and diabetes caused by a normally benign and a well-known human commensal organism, Saccharomyces cerevisiae that is very often prescribed as a probiotic in modern medical practice. The causal role of S. cerevisiae was confirmed by its isolation in blood, urine, stool as well as vaginal swabs thus proving its virulent nature in suitable situations.

  15. ISOLATION OF A CYTOCHROME P-450 STRUCTURAL GENE FROM SACCHAROMYCES CEREVISIAE

    EPA Science Inventory

    We have transformed a Saccharomyces cerevisiae host with an S. cerevisiae genomic library contained in the shuttle vector YEp24 and screened the resultant transformants for resistance to ketoconazole (Kc), an inhibitor of the cytochrome P-450 (P-450) enzyme lanosterol 14-demethyl...

  16. [The ABC transporters of Saccharomyces cerevisiae].

    PubMed

    Wawrzycka, Donata

    2011-01-01

    The ABC transporters (ATP Binding Cassette) compose one of the bigest protein family with the great medical, industrial and economical impact. They are found in all organism from bacteria to man. ABC proteins are responsible for resistance of microorganism to antibiotics and fungicides and multidrug resistance of cancer cells. Mutations in ABC transporters genes cause seriuos deseases like cystic fibrosis, adrenoleucodystrophy or ataxia. Transport catalized by ABC proteins is charged with energy from the ATP hydrolysis. The ABC superfamily contains transporters, canals, receptors. Analysis of the Saccharomyces cerevisiae genome allowed to distinguish 30 potential ABC proteins which are classified into 6 subfamilies. The structural and functional similarity of the yeast and human ABC proteins allowes to use the S. cerevisiae as a model organism for ABC transporters characterisation. In this work the present state of knowleadge on yeast S. cerevisiae ABC proteins was summarised.

  17. PCR on yeast colonies: an improved method for glyco-engineered Saccharomyces cerevisiae

    PubMed Central

    2013-01-01

    Background Saccharomyces cerevisiae is extensively used in bio-industries. However, its genetic engineering to introduce new metabolism pathways can cause unexpected phenotypic alterations. For example, humanisation of the glycosylation pathways is a high priority pharmaceutical industry goal for production of therapeutic glycoproteins in yeast. Genomic modifications can lead to several described physiological changes: biomass yields decrease, temperature sensitivity or cell wall structure modifications. We have observed that deletion of several N-mannosyltransferases in Saccharomyces cerevisiae, results in strains that can no longer be analyzed by classical PCR on yeast colonies. Findings In order to validate our glyco-engineered Saccharomyces cerevisiae strains, we developed a new protocol to carry out PCR directly on genetically modified yeast colonies. A liquid culture phase, combined with the use of a Hot Start DNA polymerase, allows a 3-fold improvement of PCR efficiency. The results obtained are repeatable and independent of the targeted sequence; as such the protocol is well adapted for intensive screening applications. Conclusions The developed protocol enables by-passing of many of the difficulties associated with PCR caused by phenotypic modifications brought about by humanisation of the glycosylation in yeast and allows rapid validation of glyco-engineered Saccharomyces cerevisiae cells. It has the potential to be extended to other yeast strains presenting cell wall structure modifications. PMID:23688076

  18. Molecular mechanisms of ethanol tolerance in Saccharomyces cerevisiae

    USDA-ARS?s Scientific Manuscript database

    The yeast Saccharomyces cerevisiae is a superb ethanol producer, yet sensitive to ethanol at higher concentrations especially under high gravity or very high gravity fermentation conditions. Although significant efforts have been made to study ethanol-stress response in past decades, molecular mecha...

  19. Anti-Saccharomyces cerevisiae autoantibodies in autoimmune diseases: from bread baking to autoimmunity.

    PubMed

    Rinaldi, Maurizio; Perricone, Roberto; Blank, Miri; Perricone, Carlo; Shoenfeld, Yehuda

    2013-10-01

    Saccharomyces cerevisiae is best known as the baker's and brewer's yeast, but its residual traces are also frequent excipients in some vaccines. Although anti-S. cerevisiae autoantibodies (ASCAs) are considered specific for Crohn's disease, a growing number of studies have detected high levels of ASCAs in patients affected with autoimmune diseases as compared with healthy controls, including antiphospholipid syndrome, systemic lupus erythematosus, type 1 diabetes mellitus, and rheumatoid arthritis. Commensal microorganisms such as Saccharomyces are required for nutrition, proper development of Peyer's aggregated lymphoid tissue, and tissue healing. However, even the commensal nonclassically pathogenic microbiota can trigger autoimmunity when fine regulation of immune tolerance does not work properly. For our purposes, the protein database of the National Center for Biotechnology Information (NCBI) was consulted, comparing Saccharomyces mannan to several molecules with a pathogenetic role in autoimmune diseases. Thanks to the NCBI bioinformation technology tool, several overlaps in molecular structures (50-100 %) were identified when yeast mannan, and the most common autoantigens were compared. The autoantigen U2 snRNP B″ was found to conserve a superfamily protein domain that shares 83 % of the S. cerevisiae mannan sequence. Furthermore, ASCAs may be present years before the diagnosis of some associated autoimmune diseases as they were retrospectively found in the preserved blood samples of soldiers who became affected by Crohn's disease years later. Our results strongly suggest that ASCAs' role in clinical practice should be better addressed in order to evaluate their predictive or prognostic relevance.

  20. Saccharomyces cerevisiae metabolism in ecological context.

    PubMed

    Jouhten, Paula; Ponomarova, Olga; Gonzalez, Ramon; Patil, Kiran R

    2016-11-01

    The architecture and regulation of Saccharomyces cerevisiae metabolic network are among the best studied owing to its widespread use in both basic research and industry. Yet, several recent studies have revealed notable limitations in explaining genotype-metabolic phenotype relations in this yeast, especially when concerning multiple genetic/environmental perturbations. Apparently unexpected genotype-phenotype relations may originate in the evolutionarily shaped cellular operating principles being hidden in common laboratory conditions. Predecessors of laboratory S. cerevisiae strains, the wild and the domesticated yeasts, have been evolutionarily shaped by highly variable environments, very distinct from laboratory conditions, and most interestingly by social life within microbial communities. Here we present a brief review of the genotypic and phenotypic peculiarities of S. cerevisiae in the context of its social lifestyle beyond laboratory environments. Accounting for this ecological context and the origin of the laboratory strains in experimental design and data analysis would be essential in improving the understanding of genotype-environment-phenotype relationships. © FEMS 2016.

  1. Saccharomyces cerevisiae metabolism in ecological context

    PubMed Central

    Jouhten, Paula; Ponomarova, Olga; Gonzalez, Ramon

    2016-01-01

    The architecture and regulation of Saccharomyces cerevisiae metabolic network are among the best studied owing to its widespread use in both basic research and industry. Yet, several recent studies have revealed notable limitations in explaining genotype–metabolic phenotype relations in this yeast, especially when concerning multiple genetic/environmental perturbations. Apparently unexpected genotype–phenotype relations may originate in the evolutionarily shaped cellular operating principles being hidden in common laboratory conditions. Predecessors of laboratory S. cerevisiae strains, the wild and the domesticated yeasts, have been evolutionarily shaped by highly variable environments, very distinct from laboratory conditions, and most interestingly by social life within microbial communities. Here we present a brief review of the genotypic and phenotypic peculiarities of S. cerevisiae in the context of its social lifestyle beyond laboratory environments. Accounting for this ecological context and the origin of the laboratory strains in experimental design and data analysis would be essential in improving the understanding of genotype–environment–phenotype relationships. PMID:27634775

  2. Outlining a future for non-Saccharomyces yeasts: selection of putative spoilage wine strains to be used in association with Saccharomyces cerevisiae for grape juice fermentation.

    PubMed

    Domizio, Paola; Romani, Cristina; Lencioni, Livio; Comitini, Francesca; Gobbi, Mirko; Mannazzu, Ilaria; Ciani, Maurizio

    2011-06-30

    The use of non-Saccharomyces yeasts that are generally considered as spoilage yeasts, in association with Saccharomyces cerevisiae for grape must fermentation was here evaluated. Analysis of the main oenological characteristics of pure cultures of 55 yeasts belonging to the genera Hanseniaspora, Pichia, Saccharomycodes and Zygosaccharomyces revealed wide biodiversity within each genus. Moreover, many of these non-Saccharomyces strains had interesting oenological properties in terms of fermentation purity, and ethanol and secondary metabolite production. The use of four non-Saccharomyces yeasts (one per genus) in mixed cultures with a commercial S. cerevisiae strain at different S. cerevisiae/non-Saccharomyces inoculum ratios was investigated. This revealed that most of the compounds normally produced at high concentrations by pure cultures of non-Saccharomyces, and which are considered detrimental to wine quality, do not reach threshold taste levels in these mixed fermentations. On the other hand, the analytical profiles of the wines produced by these mixed cultures indicated that depending on the yeast species and the S. cerevisiae/non-Saccharomyces inoculum ratio, these non-Saccharomyces yeasts can be used to increase production of polysaccharides and to modulate the final concentrations of acetic acid and volatile compounds, such as ethyl acetate, phenyl-ethyl acetate, 2-phenyl ethanol, and 2-methyl 1-butanol. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Performance evaluation of Pichia kluyveri, Kluyveromyces marxianus and Saccharomyces cerevisiae in industrial tequila fermentation.

    PubMed

    Amaya-Delgado, L; Herrera-López, E J; Arrizon, Javier; Arellano-Plaza, M; Gschaedler, A

    2013-05-01

    Traditionally, industrial tequila production has used spontaneous fermentation or Saccharomyces cerevisiae yeast strains. Despite the potential of non-Saccharomyces strains for alcoholic fermentation, few studies have been performed at industrial level with these yeasts. Therefore, in this work, Agave tequilana juice was fermented at an industrial level using two non-Saccharomyces yeasts (Pichia kluyveri and Kluyveromyces marxianus) with fermentation efficiency higher than 85 %. Pichia kluyveri (GRO3) was more efficient for alcohol and ethyl lactate production than S. cerevisiae (AR5), while Kluyveromyces marxianus (GRO6) produced more isobutanol and ethyl-acetate than S. cerevisiae (AR5). The level of volatile compounds at the end of fermentation was compared with the tequila standard regulation. All volatile compounds were within the allowed range except for methanol, which was higher for S. cerevisiae (AR5) and K. marxianus (GRO6). The variations in methanol may have been caused by the Agave tequilana used for the tests, since this compound is not synthesized by these yeasts.

  4. Saccharomyces kudriavzevii and Saccharomyces uvarum differ from Saccharomyces cerevisiae during the production of aroma-active higher alcohols and acetate esters using their amino acidic precursors.

    PubMed

    Stribny, Jiri; Gamero, Amparo; Pérez-Torrado, Roberto; Querol, Amparo

    2015-07-16

    Higher alcohols and acetate esters are important flavour and aroma components in the food industry. In alcoholic beverages these compounds are produced by yeast during fermentation. Although Saccharomyces cerevisiae is one of the most extensively used species, other species of the Saccharomyces genus have become common in fermentation processes. This study analyses and compares the production of higher alcohols and acetate esters from their amino acidic precursors in three Saccharomyces species: Saccharomyces kudriavzevii, Saccharomyces uvarum and S. cerevisiae. The global volatile compound analysis revealed that S. kudriavzevii produced large amounts of higher alcohols, whereas S. uvarum excelled in the production of acetate esters. Particularly from phenylalanine, S. uvarum produced the largest amounts of 2-phenylethyl acetate, while S. kudriavzevii obtained the greatest 2-phenylethanol formation from this precursor. The present data indicate differences in the amino acid metabolism and subsequent production of flavour-active higher alcohols and acetate esters among the closely related Saccharomyces species. This knowledge will prove useful for developing new enhanced processes in fragrance, flavour, and food industries. Copyright © 2015. Published by Elsevier B.V.

  5. 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.

  6. [Urinary infection by Saccharomyces cerevisiae: Emerging yeast?].

    PubMed

    Elkhihal, B; Elhalimi, M; Ghfir, B; Mostachi, A; Lyagoubi, M; Aoufi, S

    2015-12-01

    Saccharomyces cerevisiae is a commensal yeast of the digestive, respiratory and genito-urinary tract. It is widely used as a probiotic for the treatment of post-antibiotic diarrhea. It most often occurs in immunocompromised patients frequently causing fungemia. We report the case of an adult diabetic patient who had a urinary tract infection due to S. cerevisiae. The disease started with urination associated with urinary frequency burns without fever. The diagnosis was established by the presence of yeasts on direct examination and positivity of culture on Sabouraud-chloramphenicol three times. The auxanogramme gallery (Auxacolor BioRad(®)) allowed the identification of S. cerevisiae. The patient was put on fluconazole with good outcome. This observation points out that this is an opportunistic yeast in immunocompromised patients. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  7. Inhibition of DNA replication in Saccharomyces cerevisiae by araCMP.

    PubMed

    McIntosh, E M; Kunz, B A; Haynes, R H

    1986-01-01

    Cytosine arabinoside (araC), a potent inhibitor of DNA replication in mammalian cells, was found to be completely ineffective in Saccharomyces cerevisiae. The 5' monophosphate derivative, araCMP, is toxic and effectively inhibits both nuclear and mitochondrial DNA synthesis in this organism. Although wild-type strains can be inhibited by araCMP, dTMP permeable (tup-) strains were found to be much more sensitive to the analogue. In vivo labelling experiments indicate that araC enters yeast cells; however, it is extensively catabolized by deamination and breakage of the glycosidic bond. In addition, the analogue is not efficiently phosphorylated in S. cerevisiae owing to an apparent lack of deoxynucleoside kinase activity. These results provide further evidence that deoxyribonucleotides can be synthesized only through de novo pathways in this organism. Finally, araCMP was found to be recombinagenic in S. cerevisiae which suggests, together with other previous studies, that, in general, inhibition of DNA synthesis in yeast promotes mitotic recombination events.

  8. Anti-oxidant effects of pomegranate juice on Saccharomyces cerevisiae cell growth.

    PubMed

    Aslan, Abdullah; Can, Muhammed İsmail; Boydak, Didem

    2014-01-01

    Pomegranate juice has a number of positive effects on both human and animal subjects. Four groups were used in this study. i: Control group, ii: H2O2 group, iii: Pomegranate juice (PJ) group and iv: PJ + H2O2 group. Following the sterilization method for pomegranate juice (10%) and H2O2 (6% v/v), Saccharomyces cerevisiae cultures were added and the cultivation incubated at 35°C for 72 hours. Fatty acids and vitamin concentrations were measured using HPLC and GC and the total protein bands profile were determined by SDS-PAGE. According to our results statistically significant differences have been determined among the study groups in terms of fatty acids and vitamin (p<0,05). Fatty acid synthesis, vitamin control and cell density increased in groups to which PJ was given in comparison with the control group (p<0,05). Pomegranate juice increased vitamins, fatty acids and total protein expression in Saccharomyces cerevisiae in comparison with the control. Pomegranate juice has a positive effect on fatty acid, vitamin and protein synthesis by Saccharomyces cerevisiae. Accordingly, we believe that it has significantly decreased oxidative damage thereby making a positive impact on yeast development.

  9. Purification of Arp2/3 complex from Saccharomyces cerevisiae

    PubMed Central

    Doolittle, Lynda K.; Rosen, Michael K.; Padrick, Shae B.

    2014-01-01

    Summary Much of cellular control over actin dynamics comes through regulation of actin filament initiation. At the molecular level, this is accomplished through a collection of cellular protein machines, called actin nucleation factors, which position actin monomers to initiate a new actin filament. The Arp2/3 complex is a principal actin nucleation factor used throughout the eukaryotic family tree. The budding yeast Saccharomyces cerevisiae has proven to be not only an excellent genetic platform for the study of the Arp2/3 complex, but also an excellent source for the purification of endogenous Arp2/3 complex. Here we describe a protocol for the preparation of endogenous Arp2/3 complex from wild type Saccharomyces cerevisiae. This protocol produces material suitable for biochemical study, and yields milligram quantities of purified Arp2/3 complex. PMID:23868593

  10. Direct conversion of starch to ethanol using recombınant Saccharomyces cerevisiae containing glucoamylase gene

    NASA Astrophysics Data System (ADS)

    Purkan, P.; Baktir, A.; Puspaningsih, N. N. T.; Ni'mah, M.

    2017-09-01

    Saccharomyces cerevisiae is known for its high fermentative capacity, high ethanol yield and its high ethanol tolerance. The yeast is inability converting starch (relatively inexpensive substrate) into biofuel ethanol. Insertion of glucoamylase gene in yeast cell of Saccharomyces cerevisiae had been done to increase the yeast function in ethanol fermentation from starch. Transformation of yeast of S. cerevisiae with recombinant plasmid yEP-GLO1 carrying gene encoding glucoamylase (GLO1) produced the recombinant yeast which enable to degrade starch. Optimizing of bioconversion process of starch into ethanol by the yeast of recombinant Saccharomyces cerevisiae [yEP-GLO1] had been also done. Starch concentration which could be digested by recombinant yeast of S. cerevisiae [yEP-GLO1] was 10% (w/v). Bioconversion of starch having concentration 10% (b/v) using recombinant yeast of S. cerevisiae BY5207 [yEP-GLO1] could result ethanol as 20% (v/v) to alcoholmeter and 19,5% (v/v) to gas of chromatography. Otherwise, using recombinant yeast S. cerevisiae S. cerevisiae AS3324 [yEP-GLO1] resulted ethanol as 17% (v/v) to alcoholmeter and 17,5% (v/v) to gas of chromatography. The highest ethanol in starch bioconversion using both recombinant yeasts BY5207 and AS3324 could be resulted on 144 hours of fermentation time as well as in pH 5.

  11. Induction of homologous recombination in Saccharomyces cerevisiae.

    PubMed

    Simon, J R; Moore, P D

    1988-09-01

    We have investigated the effects of UV irradiation of Saccharomyces cerevisiae in order to distinguish whether UV-induced recombination results from the induction of enzymes required for homologous recombination, or the production of substrate sites for recombination containing regions of DNA damage. We utilized split-dose experiments to investigate the induction of proteins required for survival, gene conversion, and mutation in a diploid strain of S. cerevisiae. We demonstrate that inducing doses of UV irradiation followed by a 6 h period of incubation render the cells resistant to challenge doses of UV irradiation. The effects of inducing and challenge doses of UV irradiation upon interchromosomal gene conversion and mutation are strictly additive. Using the yeast URA3 gene cloned in non-replicating single- and double-stranded plasmid vectors that integrate into chromosomal genes upon transformation, we show that UV irradiation of haploid yeast cells and homologous plasmid DNA sequences each stimulate homologous recombination approximately two-fold, and that these effects are additive. Non-specific DNA damage has little effect on the stimulation of homologous recombination, as shown by studies in which UV-irradiated heterologous DNA was included in transformation/recombination experiments. We further demonstrate that the effect of competing single- and double-stranded heterologous DNA sequences differs in UV-irradiated and unirradiated cells, suggesting an induction of recombinational machinery in UV-irradiated S. cerevisiae cells.

  12. Screening of Non- Saccharomyces cerevisiae Strains for Tolerance to Formic Acid in Bioethanol Fermentation.

    PubMed

    Oshoma, Cyprian E; Greetham, Darren; Louis, Edward J; Smart, Katherine A; Phister, Trevor G; Powell, Chris; Du, Chenyu

    2015-01-01

    Formic acid is one of the major inhibitory compounds present in hydrolysates derived from lignocellulosic materials, the presence of which can significantly hamper the efficiency of converting available sugars into bioethanol. This study investigated the potential for screening formic acid tolerance in non-Saccharomyces cerevisiae yeast strains, which could be used for the development of advanced generation bioethanol processes. Spot plate and phenotypic microarray methods were used to screen the formic acid tolerance of 7 non-Saccharomyces cerevisiae yeasts. S. kudriavzeii IFO1802 and S. arboricolus 2.3319 displayed a higher formic acid tolerance when compared to other strains in the study. Strain S. arboricolus 2.3319 was selected for further investigation due to its genetic variability among the Saccharomyces species as related to Saccharomyces cerevisiae and availability of two sibling strains: S. arboricolus 2.3317 and 2.3318 in the lab. The tolerance of S. arboricolus strains (2.3317, 2.3318 and 2.3319) to formic acid was further investigated by lab-scale fermentation analysis, and compared with S. cerevisiae NCYC2592. S. arboricolus 2.3319 demonstrated improved formic acid tolerance and a similar bioethanol synthesis capacity to S. cerevisiae NCYC2592, while S. arboricolus 2.3317 and 2.3318 exhibited an overall inferior performance. Metabolite analysis indicated that S. arboricolus strain 2.3319 accumulated comparatively high concentrations of glycerol and glycogen, which may have contributed to its ability to tolerate high levels of formic acid.

  13. Screening of Non- Saccharomyces cerevisiae Strains for Tolerance to Formic Acid in Bioethanol Fermentation

    PubMed Central

    Oshoma, Cyprian E.; Greetham, Darren; Louis, Edward J.; Smart, Katherine A.; Phister, Trevor G.; Powell, Chris; Du, Chenyu

    2015-01-01

    Formic acid is one of the major inhibitory compounds present in hydrolysates derived from lignocellulosic materials, the presence of which can significantly hamper the efficiency of converting available sugars into bioethanol. This study investigated the potential for screening formic acid tolerance in non-Saccharomyces cerevisiae yeast strains, which could be used for the development of advanced generation bioethanol processes. Spot plate and phenotypic microarray methods were used to screen the formic acid tolerance of 7 non-Saccharomyces cerevisiae yeasts. S. kudriavzeii IFO1802 and S. arboricolus 2.3319 displayed a higher formic acid tolerance when compared to other strains in the study. Strain S. arboricolus 2.3319 was selected for further investigation due to its genetic variability among the Saccharomyces species as related to Saccharomyces cerevisiae and availability of two sibling strains: S. arboricolus 2.3317 and 2.3318 in the lab. The tolerance of S. arboricolus strains (2.3317, 2.3318 and 2.3319) to formic acid was further investigated by lab-scale fermentation analysis, and compared with S. cerevisiae NCYC2592. S. arboricolus 2.3319 demonstrated improved formic acid tolerance and a similar bioethanol synthesis capacity to S. cerevisiae NCYC2592, while S. arboricolus 2.3317 and 2.3318 exhibited an overall inferior performance. Metabolite analysis indicated that S. arboricolus strain 2.3319 accumulated comparatively high concentrations of glycerol and glycogen, which may have contributed to its ability to tolerate high levels of formic acid. PMID:26284784

  14. 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

  15. Prevalence and susceptibility of Saccharomyces cerevisiae causing vaginitis in Greek women.

    PubMed

    Papaemmanouil, V; Georgogiannis, N; Plega, M; Lalaki, J; Lydakis, D; Dimitriou, M; Papadimitriou, A

    2011-12-01

    Saccharomyces cerevisiae is an ascomycetous yeast, that is traditionally used in wine bread and beer production. Vaginitis caused by S. cerevisiae is rare. The aim of this study was to evaluate the frequency of S. cerevisiae isolation from the vagina in two groups of women and determined the in vitro susceptibility of this fungus. Vaginal samples were collected from a total of 262 (asymptomatic and symptomatic) women with vaginitis attending the centre of family planning of General hospital of Piraeus. All blastomycetes that isolated from the vaginal samples were examined for microscopic morphological tests and identified by conventional methods: By API 20 C AUX and ID 32 C (Biomerieux). Antifungal susceptibility testing for amphotericin B,fluconazole itraconazole,voriconazole, posaconazole and caspofungin was performed by E -test (Ab BIODIKS SWEDEN) against S. cerevisiae. A total of 16 isolates of S. cerevisiae derived from vaginal sample of the referred women, average 6.10%. Susceptibility of 16 isolates of S. cerevisiae to a variety of antimycotic agents were obtained. So all isolates of S. cerevisiae were resistant to fluconazole, posaconazole and intraconazole, but they were sensitive to voriconazole caspofungin and Amphotericin B which were found sensitive (except 1/16 strains). None of the 16 patients had a history of occupational domestic use of baker's yeast. Vaginitis caused by S. cerevisiae occur, is rising and cannot be ignored. Treatment of Saccharomyces vaginitis constitutes a major challenge and may require selected and often prolonged therapy. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Efficient screening of environmental isolates for Saccharomyces cerevisiae strains that are suitable for brewing.

    PubMed

    Fujihara, Hidehiko; Hino, Mika; Takashita, Hideharu; Kajiwara, Yasuhiro; Okamoto, Keiko; Furukawa, Kensuke

    2014-01-01

    We developed an efficient screening method for Saccharomyces cerevisiae strains from environmental isolates. MultiPlex PCR was performed targeting four brewing S. cerevisiae genes (SSU1, AWA1, BIO6, and FLO1). At least three genes among the four were amplified from all S. cerevisiae strains. The use of this method allowed us to successfully obtain S. cerevisiae strains.

  17. Selected non-Saccharomyces wine yeasts in controlled multistarter fermentations with Saccharomyces cerevisiae on alcoholic fermentation behaviour and wine aroma of cherry wines.

    PubMed

    Sun, Shu Yang; Gong, Han Sheng; Jiang, Xiao Man; Zhao, Yu Ping

    2014-12-01

    This study examined the effect of mixed fermentation of non-Saccharomyces (Torulaspora delbrueckii ZYMAFLORE Alpha(TD n. Sacch) and Metschnikowia pulcherrima JS22) and Saccharomyces cerevisiae yeasts (D254 and EC1118) on the production of cherry wines, in comparison with commonly used mono-culture. Results obtained during AF demonstrated that negligible inhibitory effect was observed in S. cerevisiae/Alpha pair, whereas a strong antagonistic effect was detected between MJS22 and S. cerevisiae strain, resulting in an early death of MJS22. For volatile components determined, S. cerevisiae/MJS22 couple was found to significantly boost the production of most detected compounds, more particularly in higher alcohols, esters, acids and terpenes; while the characteristic of S. cerevisiae/Alpha pair is an increase in fruity esters, higher alcohols and decrease in acid production. Sensory evaluation revealed that S. cerevisiae/MJS22 pair reinforced sweet, green and fatty notes to the cherry wines, and S. cerevisiae/Alpha trial enhanced the fruity odour and reduced green note. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Overproduction of geraniol by enhanced precursor supply in Saccharomyces cerevisiae.

    PubMed

    Liu, Jidong; Zhang, Weiping; Du, Guocheng; Chen, Jian; Zhou, Jingwen

    2013-12-01

    Monoterpene geraniol, a compound obtained from aromatic plants, has wide applications. In this study, geraniol was synthesized in Saccharomyces cerevisiae through the introduction of geraniol synthase. To increase geraniol production, the mevalonate pathway in S. cerevisiae was genetically manipulated to enhance the supply of geranyl diphosphate, a substrate used for the biosynthesis of geraniol. Identification and optimization of the key regulatory points in the mevalonate pathway in S. cerevisiae increased geraniol production to 36.04 mg L(-1). The results obtained revealed that the IDI1-encoded isopentenyl diphosphate isomerase is a rate-limiting enzyme in the biosynthesis of geraniol in S. cerevisiae, and overexpression of MAF1, a negative regulator in tRNA biosynthesis, is another effective method to increase geraniol production in S. cerevisiae. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. [Invertase Overproduction May Provide for Inulin Fermentation by Selection Strains of Saccharomyces cerevisiae].

    PubMed

    Naumov, G I; Naumova, E S

    2015-01-01

    In some recent publications, the ability of selection strains of Saccharomyces cerevisiae to ferment inulin was attributed to inulinase activity. The review summarizes the literature data indicating that overproduction of invertase, an enzyme common to S. cerevisiae, may be responsible for this phenomenon.

  20. Exploring the northern limit of the distribution of Saccharomyces cerevisiae and Saccharomyces paradoxus in North America.

    PubMed

    Charron, Guillaume; Leducq, Jean-Baptiste; Bertin, Chloé; Dubé, Alexandre K; Landry, Christian R

    2014-03-01

    We examined the northern limit of Saccharomyces cerevisiae and Saccharomyces paradoxus in northeast America. We collected 876 natural samples at 29 sites and applied enrichment methods for the isolation of mesophilic yeasts. We uncovered a large diversity of yeasts, in some cases, associated with specific substrates. Sequencing of the ITS1, 5.8S and ITS2 loci allowed to assign 226 yeast strains at the species level, including 41 S. paradoxus strains. Our intensive sampling suggests that if present, S. cerevisiae is rare at these northern latitudes. Our sampling efforts spread across several months of the year revealed that successful sampling increases throughout the summer and diminishes significantly at the beginning of the fall. The data obtained on the ecological context of yeasts corroborate what was previously reported on Pichiaceae, Saccharomycodaceae, Debaryomycetaceae and Phaffomycetaceae yeast families. We identified 24 yeast isolates that could not be assigned to any known species and that may be of taxonomic, medical, or biotechnological importance. Our study reports new data on the taxonomic diversity of yeasts and new resources for studying the evolution and ecology of S. paradoxus. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  1. Potential immobilized Saccharomyces cerevisiae as heavy metal removal

    NASA Astrophysics Data System (ADS)

    Raffar, Nur Izzati Abdul; Rahman, Nadhratul Nur Ain Abdul; Alrozi, Rasyidah; Senusi, Faraziehan; Chang, Siu Hua

    2015-05-01

    Biosorption of copper ion using treated and untreated immobilized Saccharomyces cerevisiae from aqueous solution was investigate in this study. S.cerevisiae has been choosing as biosorbent due to low cost, easy and continuously available from various industries. In this study, the ability of treated and untreated immobilized S.cerevisiae in removing copper ion influence by the effect of pH solution, and initial concentration of copper ion with contact time. Besides, adsorption isotherm and kinetic model also studied. The result indicated that the copper ion uptake on treated and untreated immobilized S.cerevisiae was increased with increasing of contact time and initial concentration of copper ion. The optimum pH for copper ion uptake on untreated and treated immobilized S.cerevisiae at 4 and 6. From the data obtained of copper ion uptake, the adsorption isotherm was fitted well by Freundlich model for treated immobilized S.cerevisiae and Langmuir model for untreated immobilized S.cerevisiae according to high correlation coefficient. Meanwhile, the pseudo second order was described as suitable model present according to high correlation coefficient. Since the application of biosorption process has been received more attention from numerous researchers as a potential process to be applied in the industry, future study will be conducted to investigate the potential of immobilized S.cerevisiae in continuous process.

  2. Habitat Predicts Levels of Genetic Admixture in Saccharomyces cerevisiae.

    PubMed

    Tilakaratna, Viranga; Bensasson, Douda

    2017-09-07

    Genetic admixture can provide material for populations to adapt to local environments, and this process has played a crucial role in the domestication of plants and animals. The model yeast, Saccharomyces cerevisiae , has been domesticated multiple times for the production of wine, sake, beer, and bread, but the high rate of admixture between yeast lineages has so far been treated as a complication for population genomic analysis. Here, we make use of the low recombination rate at centromeres to investigate admixture in yeast using a classic Bayesian approach and a locus-by-locus phylogenetic approach. Using both approaches, we find that S. cerevisiae from stable oak woodland habitats are less likely to show recent genetic admixture compared with those isolated from transient habitats such as fruits, wine, or human infections. When woodland yeast strains do show recent genetic admixture, the degree of admixture is lower than in strains from other habitats. Furthermore, S. cerevisiae populations from oak woodlands are genetically isolated from each other, with only occasional migration between woodlands and local fruit habitats. Application of the phylogenetic approach suggests that there is a previously undetected population in North Africa that is the closest outgroup to the European S. cerevisiae , including the domesticated Wine population. Careful testing for admixture in S. cerevisiae leads to a better understanding of the underlying population structure of the species and will be important for understanding the selective processes underlying domestication in this economically important species. Copyright © 2017 Tilakaratna and Bensasson.

  3. Progress in Metabolic Engineering of Saccharomyces cerevisiae

    PubMed Central

    Nevoigt, Elke

    2008-01-01

    Summary: The traditional use of the yeast Saccharomyces cerevisiae in alcoholic fermentation has, over time, resulted in substantial accumulated knowledge concerning genetics, physiology, and biochemistry as well as genetic engineering and fermentation technologies. S. cerevisiae has become a platform organism for developing metabolic engineering strategies, methods, and tools. The current review discusses the relevance of several engineering strategies, such as rational and inverse metabolic engineering, evolutionary engineering, and global transcription machinery engineering, in yeast strain improvement. It also summarizes existing tools for fine-tuning and regulating enzyme activities and thus metabolic pathways. Recent examples of yeast metabolic engineering for food, beverage, and industrial biotechnology (bioethanol and bulk and fine chemicals) follow. S. cerevisiae currently enjoys increasing popularity as a production organism in industrial (“white”) biotechnology due to its inherent tolerance of low pH values and high ethanol and inhibitor concentrations and its ability to grow anaerobically. Attention is paid to utilizing lignocellulosic biomass as a potential substrate. PMID:18772282

  4. The postmitotic Saccharomyces cerevisiae after spaceflight showed higher viability

    NASA Astrophysics Data System (ADS)

    Yi, Zong-Chun; Li, Xiao-Fei; Wang, Yan; Wang, Jie; Sun, Yan; Zhuang, Feng-Yuan

    2011-06-01

    The budding yeast Saccharomyces cerevisiae has been proposed as an ideal model organism for clarifying the biological effects caused by spaceflight conditions. The postmitotic S. cerevisiae cells onboard Practice eight recoverable satellite were subjected to spaceflight for 15 days. After recovery, the viability, the glycogen content, the activities of carbohydrate metabolism enzymes, the DNA content and the lipid peroxidation level in yeast cells were analyzed. The viability of the postmitotic yeast cells after spaceflight showed a three-fold increase as compared with that of the ground control cells. Compared to the ground control cells, the lipid peroxidation level in the spaceflight yeast cells markedly decreased. The spaceflight yeast cells also showed an increase in G2/M cell population and a decrease in Sub-G1 cell population. The glycogen content and the activities of hexokinase and succinate dehydrogenase significantly decreased in the yeast cells after spaceflight. In contrast, the activity of malate dehydrogenase showed an obvious increase after spaceflight. These results suggested that microgravity or spaceflight could promote the survival of postmitotic S. cerevisiae cells through regulating carbohydrate metabolism, ROS level and cell cycle progression.

  5. 2μ plasmid in Saccharomyces species and in Saccharomyces cerevisiae.

    PubMed

    Strope, Pooja K; Kozmin, Stanislav G; Skelly, Daniel A; Magwene, Paul M; Dietrich, Fred S; McCusker, John H

    2015-12-01

    We determined that extrachromosomal 2μ plasmid was present in 67 of the Saccharomyces cerevisiae 100-genome strains; in addition to variation in the size and copy number of 2μ, we identified three distinct classes of 2μ. We identified 2μ presence/absence and class associations with populations, clinical origin and nuclear genotypes. We also screened genome sequences of S. paradoxus, S. kudriavzevii, S. uvarum, S. eubayanus, S. mikatae, S. arboricolus and S. bayanus strains for both integrated and extrachromosomal 2μ. Similar to S. cerevisiae, we found no integrated 2μ sequences in any S. paradoxus strains. However, we identified part of 2μ integrated into the genomes of some S. uvarum, S. kudriavzevii, S. mikatae and S. bayanus strains, which were distinct from each other and from all extrachromosomal 2μ. We identified extrachromosomal 2μ in one S. paradoxus, one S. eubayanus, two S. bayanus and 13 S. uvarum strains. The extrachromosomal 2μ in S. paradoxus, S. eubayanus and S. cerevisiae were distinct from each other. In contrast, the extrachromosomal 2μ in S. bayanus and S. uvarum strains were identical with each other and with one of the three classes of S. cerevisiae 2μ, consistent with interspecific transfer. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Functional relevance of water and glycerol channels in Saccharomyces cerevisiae.

    PubMed

    Sabir, Farzana; Loureiro-Dias, Maria C; Soveral, Graça; Prista, Catarina

    2017-05-01

    Our understanding of the functional relevance of orthodox aquaporins and aquaglyceroporins in Saccharomyces cerevisiae is essentially based on phenotypic variations obtained by expression/overexpression/deletion of these major intrinsic proteins in selected strains. These water/glycerol channels are considered crucial during various life-cycle phases, such as sporulation and mating and in some life processes such as rapid freeze-thaw tolerance, osmoregulation and phenomena associated with cell surface. Despite their putative functional roles not only as channels but also as sensors, their underlying mechanisms and their regulation are still poorly understood. In the present review, we summarize and discuss the physiological relevance of S. cerevisiae aquaporins (Aqy1 and Aqy2) and aquaglyceroporins (Fps1 and Yfl054c). In particular, the fact that most S. cerevisiae laboratory strains harbor genes coding for non-functional aquaporins, while wild and industrial strains possess at least one functional aquaporin, suggests that aquaporin activity is required for cell survival under more harsh conditions. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  7. Antioxidant properties and global metabolite screening of the probiotic yeast Saccharomyces cerevisiae var. boulardii.

    PubMed

    Datta, Suprama; Timson, David J; Annapure, Uday S

    2017-07-01

    Saccharomyces cerevisiae var. boulardii is the only yeast species with probiotic properties. It is considered to have therapeutic significance in gastrointestinal disorders. In the present study, a comparative physiological study between this yeast and Saccharomyces cerevisiae (BY4742) was performed by evaluating two prominent traits of probiotic species, responses to different stress conditions and antioxidant capacity. A global metabolite profile was also developed aiming to identify which therapeutically important secondary metabolites are produced. Saccharomyces cerevisiae var. boulardii showed no significant difference in growth patterns but greater stress tolerance compared to S. cerevisiae. It also demonstrated a six- to 10-fold greater antioxidant potential (judged by the 1,1-diphenyl-2-picrylhydrazyl assay), with a 70-fold higher total phenolic content and a 20-fold higher total flavonoid content in the extracellular fraction. These features were clearly differentiated by principal component analysis and further indicated by metabolite profiling. The extracellular fraction of the S. cerevisiae var. boulardii cultures was found to be rich in polyphenolic metabolites: vanillic acid, cinnamic acid, phenyl ethyl alcohol (rose oil), erythromycin, amphetamine and vitamin B 6 , which results in the antioxidant capacity of this strain. The present study presents a new perspective for differentiating the two genetically related strains of yeast, S. cerevisiae and S. cerevisiae var. boulardii by assessing their metabolome fingerprints. In addition to the correlation of the phenotypic properties with the secretory metabolites of these two yeasts, the present study also emphasizes the potential to exploit S. cerevisiae var. boulardii in the industrial production of these metabolites. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  8. Microbially induced separation of quartz from calcite using Saccharomyces cerevisiae.

    PubMed

    Padukone, S Usha; Natarajan, K A

    2011-11-01

    Cells of Saccharomyces cerevisiae and their metabolites were successfully utilized to achieve selective separation of quartz and calcite through microbially induced flotation and flocculation. S. cerevisiae was adapted to calcite and quartz minerals. Adsorption studies and electrokinetic investigations were carried out to understand the changes in the surface chemistry of yeast cells and the minerals after mutual interaction. Possible mechanisms in microbially induced flotation and flocculation are outlined. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. The Reference Genome Sequence of Saccharomyces cerevisiae: Then and Now

    PubMed Central

    Engel, Stacia R.; Dietrich, Fred S.; Fisk, Dianna G.; Binkley, Gail; Balakrishnan, Rama; Costanzo, Maria C.; Dwight, Selina S.; Hitz, Benjamin C.; Karra, Kalpana; Nash, Robert S.; Weng, Shuai; Wong, Edith D.; Lloyd, Paul; Skrzypek, Marek S.; Miyasato, Stuart R.; Simison, Matt; Cherry, J. Michael

    2014-01-01

    The genome of the budding yeast Saccharomyces cerevisiae was the first completely sequenced from a eukaryote. It was released in 1996 as the work of a worldwide effort of hundreds of researchers. In the time since, the yeast genome has been intensively studied by geneticists, molecular biologists, and computational scientists all over the world. Maintenance and annotation of the genome sequence have long been provided by the Saccharomyces Genome Database, one of the original model organism databases. To deepen our understanding of the eukaryotic genome, the S. cerevisiae strain S288C reference genome sequence was updated recently in its first major update since 1996. The new version, called “S288C 2010,” was determined from a single yeast colony using modern sequencing technologies and serves as the anchor for further innovations in yeast genomic science. PMID:24374639

  10. Genetic engineering of industrial strains of Saccharomyces cerevisiae.

    PubMed

    Le Borgne, Sylvie

    2012-01-01

    Genetic engineering has been successfully applied to Saccharomyces cerevisiae laboratory strains for different purposes: extension of substrate range, improvement of productivity and yield, elimination of by-products, improvement of process performance and cellular properties, and extension of product range. The potential of genetically engineered yeasts for the massive production of biofuels as bioethanol and other nonfuel products from renewable resources as lignocellulosic biomass hydrolysates has been recognized. For such applications, robust industrial strains of S. cerevisiae have to be used. Here, some relevant genetic and genomic characteristics of industrial strains are discussed in relation to the problematic of the genetic engineering of such strains. General molecular tools applicable to the manipulation of S. cerevisiae industrial strains are presented and examples of genetically engineered industrial strains developed for the production of bioethanol from lignocellulosic biomass are given.

  11. Epigenetics in Saccharomyces cerevisiae

    PubMed Central

    Grunstein, Michael; Gasser, Susan M.

    2013-01-01

    Saccharomyces cerevisiae provides a well-studied model system for heritable silent chromatin, in which a nonhistone protein complex—the SIR complex—represses genes by spreading in a sequence-independent manner, much like heterochromatin in higher eukaryotes. The ability to study mutations in histones and to screen genome-wide for mutations that impair silencing has yielded an unparalleled depth of detail about this system. Recent advances in the biochemistry and structural biology of the SIR-chromatin complex bring us much closer to a molecular understanding of how Sir3 selectively recognizes the deacetylated histone H4 tail and demethylated histone H3 core. The existence of appropriate mutants has also shown how components of the silencing machinery affect physiological processes beyond transcriptional repression. PMID:23818500

  12. Complete Sequence of the Intronless Mitochondrial Genome of the Saccharomyces cerevisiae Strain CW252

    PubMed Central

    2018-01-01

    ABSTRACT The mitochondrial genomes of Saccharomyces cerevisiae strains contain up to 13 introns. An intronless recombinant genome introduced into the nuclear background of S. cerevisiae strain W303 gave the S. cerevisiae CW252 strain, which is used to model mitochondrial respiratory pathologies. The complete sequence of this mitochondrial genome was obtained using a hybrid assembling methodology. PMID:29700138

  13. Can Zymomonas mobilis Substitute Saccharomyces cerevisiae in Cereal Dough Leavening?

    PubMed Central

    Musatti, Alida; Mapelli, Chiara

    2018-01-01

    Baker’s yeast intolerance is rising among Western populations, where Saccharomyces cerevisiae is spread in fermented food and food components. Zymomonas mobilis is a bacterium commonly used in tropical areas to produce alcoholic beverages, and it has only rarely been considered for dough leavening probably because it only ferments glucose, fructose and sucrose, which are scarcely present in flour. However, through alcoholic fermentation, similarly to S. cerevisiae, it provides an equimolar mixture of ethanol and CO2 that can rise a dough. Here, we propose Z. mobilis as a new leavening agent, as an alternative to S. cerevisiae, overcoming its technological limit with different strategies: (1) adding glucose to the dough formulation; and (2) exploiting the maltose hydrolytic activity of Lactobacillus sanfranciscensis associated with Z. mobilis. CO2 production, dough volume increase, pH value, microbial counts, sugars consumption and ethanol production were monitored. Results suggest that glucose addition to the dough lets Z. mobilis efficiently leaven a dough, while glucose released by L. sanfranciscensis is not so well fermented by Z. mobilis, probably due to the strong acidification. Nevertheless, the use of Z. mobilis as a leavening agent could contribute to increasing the variety of baked goods alternative to those leavened by S. cerevisiae. PMID:29659515

  14. Signature pathway expression of xylose utilization in the genetically engineered industrial yeast Saccharomyces cerevisiae

    USDA-ARS?s Scientific Manuscript database

    Background: The limited xylose utilizing ability of native Saccharomyces cerevisiae has been a major obstacle for efficient cellulosic ethanol production from lignocellulosic materials. Haploid laboratory strains of S. cerevisiae are commonly used for genetic engineering to enable its xylose utiliza...

  15. Feasibility of brewing makgeolli using Pichia anomala Y197-13, a non-Saccharomyces cerevisiae.

    PubMed

    Kim, Hye Ryun; Kim, Jae-Ho; Bai, Dong-Hoon; Ahn, ByungHak

    2012-12-01

    Makgeolli is a traditional rice wine favored by the general public in Korea. This study investigated the fermentation and sensory characteristics of using wild yeast strains for brewing makgeolli. A non-Saccharomyces cerevisiae strain was isolated from nuruk and termed Y197-13. It showed 98% similarity to Pichia anomala and had an optimal growth temperature of 25 degrees C. Makgeolli was manufactured using koji, jinju nuruk, and improved nuruk as fermentation agents. Y197-13 makgeolli brewed with koji had alcohol and solids contents of 11.1% and 13.9%, respectively. Sweet sensory characteristics were attributed to residual sugars in makgeolli with 6% alcohol. The makgeolli had a fresh sour taste and carbonated taste. Volatile component analysis showed the isoamyl alcohol, phenylethyl alcohol, isoamyl acetate, and fatty acid, including ethyl oleate and ethyl linoleate, relative peak area was higher in Y197-13 makgeolli than in makgeolli with Saccharomyces cerevisiae. These results suggest the wild yeast, Y197-13, as a candidate for brewing makgeolli.

  16. Induction and characterization of morphologic mutants in a natural Saccharomyces cerevisiae strain.

    PubMed

    Barberio, Claudia; Bianchi, Lucia; Pinzauti, Francesca; Lodi, Tiziana; Ferrero, Iliana; Polsinelli, Mario; Casalone, Enrico

    2007-02-01

    Saccharomyces cerevisiae is a good model with which to study the effects of morphologic differentiation on the ecological behaviour of fungi. In this work, 33 morphologic mutants of a natural strain of S. cerevisiae, obtained with UV mutagenesis, were selected for their streak shape and cell shape on rich medium. Two of them, showing both high sporulation proficiency and constitutive pseudohyphal growth, were analysed from a genetic and physiologic point of view. Each mutant carries a recessive monogenic mutation, and the two mutations reside in unlinked genes. Flocculation ability and responsiveness to different stimuli distinguished the two mutants. Growth at 37 degrees C affected the cell but not the colony morphology, suggesting that these two phenotypes are regulated differently. The effect of ethidium bromide, which affects mitochondrial DNA replication, suggested a possible "retrograde action" of mitochondria in pseudohyphal growth.

  17. Effects of spaceflight on polysaccharides of Saccharomyces cerevisiae cell wall.

    PubMed

    Liu, Hong-Zhi; Wang, Qiang; Liu, Xiao-Yong; Tan, Sze-Sze

    2008-12-01

    Freeze-dried samples of four Saccharomyces cerevisiae strains, namely, FL01, FL03, 2.0016, and 2.1424, were subjected to spaceflight. After the satellite's landing on Earth, the samples were recovered and changes in yeast cell wall were analyzed. Spaceflight strains of all S. cerevisiae strains showed significant changes in cell wall thickness (P < 0.05). One mutant of S. cerevisiae 2.0016 with increased biomass, cell wall thickness, and cell wall glucan was isolated (P < 0.05). The spaceflight mutant of S. cerevisiae 2.0016 showed 46.7%, 62.6%, and 146.0% increment in biomass, cell wall thickness and beta-glucan content, respectively, when compared to the ground strain. Moreover, growth curve analysis showed spaceflight S. cerevisiae 2.0016 had a faster growth rate, shorter lag phase periods, higher final biomass, and higher content of beta-glucan. Genetic stability analysis showed that prolonged subculturing of spaceflight strain S. cerevisiae 2.0016 did not lead to the appearance of variants, indicating that the genetic stability of S. cerevisiae 2.0016 mutant could be sufficient for its exploitation of beta-glucan production.

  18. Early transcriptional response to biotic stress in mixed starter fermentations involving Saccharomyces cerevisiae and Torulaspora delbrueckii.

    PubMed

    Tronchoni, Jordi; Curiel, Jose Antonio; Morales, Pilar; Torres-Pérez, Rafael; Gonzalez, Ramon

    2017-01-16

    Advances in microbial wine biotechnology have led to the recent commercialization of several non-Saccharomyces starter cultures. These are intended to be used in either simultaneous or sequential inoculation with Saccharomyces cerevisiae. The different types of microbial interactions that can be stablished during wine fermentation acquire an increased relevance in the context of these mixed-starter fermentations. We analysed the transcriptional response to co-cultivation of S. cerevisiae and Torulaspora delbrueckii. The study focused in the initial stages of wine fermentation, before S. cerevisiae completely dominates the mixed cultures. Both species showed a clear response to the presence of each other, even though the portion of the genome showing altered transcription levels was relatively small. Changes in the transcription pattern suggested a stimulation of metabolic activity and growth, as a consequence of the presence of competitors in the same medium. The response of S. cerevisiae seems to take place earlier, as compared to T. delbrueckii. Enhanced glycolytic activity of the mixed culture was confirmed by the CO 2 production profile during these early stages of fermentation. Interestingly, HSP12 expression appeared induced by co-cultivation for both of S. cerevisiae and Torulaspora delbrueckii in the two time points studied. This might be related with a recently described role of Hsp12 in intercellular communication in yeast. Expression of S. cerevisiae PAU genes was also stimulated in mixed cultures. Copyright © 2016. Published by Elsevier B.V.

  19. Formation of AAV Single Stranded DNA Genome from a Circular Plasmid in Saccharomyces cerevisiae

    PubMed Central

    Cervelli, Tiziana; Backovic, Ana; Galli, Alvaro

    2011-01-01

    Adeno-associated virus (AAV)-based vectors are promising tools for targeted transfer in gene therapy studies. Many efforts have been accomplished to improve production and purification methods. We thought to develop a simple eukaryotic system allowing AAV replication which could provide an excellent opportunity for studying AAV biology and, more importantly, for AAV vector production. It has been shown that yeast Saccharomyces cerevisiae is able to replicate and form the capsid of many viruses. We investigated the ability of the yeast Saccharomyces cerevisiae to carry out the replication of a recombinant AAV (rAAV). When a plasmid containing a rAAV genome in which the cap gene was replaced with the S. cerevisiae URA3 gene, was co-transformed in yeast with a plasmid expressing Rep68, a significant number of URA3+ clones were scored (more than 30-fold over controls). Molecular analysis of low molecular weight DNA by Southern blotting revealed that single stranded DNA is formed and that the plasmid is entirely replicated. The ssDNA contains the ITRs, URA3 gene and also vector sequences suggesting the presence of two distinct molecules. Its formation was dependent on Rep68 expression and ITR. These data indicate that DNA is not obtained by the canonical AAV replication pathway. PMID:21853137

  20. Formation of AAV single stranded DNA genome from a circular plasmid in Saccharomyces cerevisiae.

    PubMed

    Cervelli, Tiziana; Backovic, Ana; Galli, Alvaro

    2011-01-01

    Adeno-associated virus (AAV)-based vectors are promising tools for targeted transfer in gene therapy studies. Many efforts have been accomplished to improve production and purification methods. We thought to develop a simple eukaryotic system allowing AAV replication which could provide an excellent opportunity for studying AAV biology and, more importantly, for AAV vector production. It has been shown that yeast Saccharomyces cerevisiae is able to replicate and form the capsid of many viruses. We investigated the ability of the yeast Saccharomyces cerevisiae to carry out the replication of a recombinant AAV (rAAV). When a plasmid containing a rAAV genome in which the cap gene was replaced with the S. cerevisiae URA3 gene, was co-transformed in yeast with a plasmid expressing Rep68, a significant number of URA3(+) clones were scored (more than 30-fold over controls). Molecular analysis of low molecular weight DNA by Southern blotting revealed that single stranded DNA is formed and that the plasmid is entirely replicated. The ssDNA contains the ITRs, URA3 gene and also vector sequences suggesting the presence of two distinct molecules. Its formation was dependent on Rep68 expression and ITR. These data indicate that DNA is not obtained by the canonical AAV replication pathway.

  1. Invertase SUC2 Is the key hydrolase for inulin degradation in Saccharomyces cerevisiae.

    PubMed

    Wang, Shi-An; Li, Fu-Li

    2013-01-01

    Specific Saccharomyces cerevisiae strains were recently found to be capable of efficiently utilizing inulin, but genetic mechanisms of inulin hydrolysis in yeast remain unknown. Here we report functional characteristics of invertase SUC2 from strain JZ1C and demonstrate that SUC2 is the key enzyme responsible for inulin metabolism in S. cerevisiae.

  2. Glucose-free fructose production from Jerusalem artichoke using a recombinant inulinase-secreting Saccharomyces cerevisiae strain.

    PubMed

    Yu, Jing; Jiang, Jiaxi; Ji, Wangming; Li, Yuyang; Liu, Jianping

    2011-01-01

    Using inulin (polyfructose) obtained from Jerusalen artichokes, we have produced fructose free of residual glucose using a recombinant inulinase-secreting strain of Saccharomyces cerevisiae in a one-step fermentation of Jerusalem artichoke tubers. For producing fructose from inulin, a recombinant inulinase-producing Saccharomyce cerevisiae strain was constructed with a deficiency in fructose uptake by disruption of two hexokinase genes hxk1 and hxk2. The inulinase gene introduced into S. cerevisiae was cloned from Kluyveromyces cicerisporus. Extracellular inulinase activity of the recombinant hxk-mutated S. cerevisiae strain reached 31 U ml(-1) after 96 h growth. When grown in a medium containing Jerusalem artichoke tubers as the sole component without any additives, the recombinant yeast accumulated fructose up to 9.2% (w/v) in the fermentation broth with only 0.1% (w/v) glucose left after 24 h.

  3. Metabolic changes induced during adaptation of Saccharomyces cerevisiae to a water stress.

    PubMed

    Singh, K K; Norton, R S

    1991-01-01

    When exponentially growing Saccharomyces cerevisiae was transferred from a normal high water activity growth medium (aw 0.997) to a medium containing 8% NaCl low water activity growth medium (aw 0.955), glycerol accumulation during the first eight hours of the adaptation was both retarded and greatly diminished in magnitude. Investigation of the underlying reasons for the slow onset of glycerol accumulation revealed that not only was overall glycerol production reduced by salt transfer, but also the rates of ethanol production and glucose consumption were reduced. Measurement of glycolytic intermediates revealed an accumulation of glucose-6-phosphate, fructose-6-phosphate, fructose 1,6 bisphosphate and phosphoenolpyruvate in S. cerevisiae 3 to 4 h after transfer to salt, suggesting that one or more glycolytic enzymes were inhibited. Potassium ions accumulated in S. cerevisiae after salt transfer and reached a maximum about 6 h after transfer, whereas the sodium ion content increased progressively during the adaptation period. The trehalose content also increased in adapting cells. It is suggested that inhibition of glycerol production during the initial period of adaptation could be due to either the inhibition of glycerol-3-phosphate dehydrogenase by increased cation content or the inhibition of glycolysis, glycerol being produced glycolytically in S. cerevisiae. The increased accumulation of glycerol towards the end of the 8-h period suggests that the osmoregulatory response of S. cerevisiae involves complex sets of adjustments in which inhibition of glycerol-3-phosphate dehydrogenase must be relieved before glycerol functions as a major osmoregulator.

  4. Loss of lager specific genes and subtelomeric regions define two different Saccharomyces cerevisiae lineages for Saccharomyces pastorianus Group I and II strains.

    PubMed

    Monerawela, Chandre; James, Tharappel C; Wolfe, Kenneth H; Bond, Ursula

    2015-03-01

    Lager yeasts, Saccharomyces pastorianus, are interspecies hybrids between S. cerevisiae and S. eubayanus and are classified into Group I and Group II clades. The genome of the Group II strain, Weihenstephan 34/70, contains eight so-called 'lager-specific' genes that are located in subtelomeric regions. We evaluated the origins of these genes through bioinformatic and PCR analyses of Saccharomyces genomes. We determined that four are of cerevisiae origin while four originate from S. eubayanus. The Group I yeasts contain all four S. eubayanus genes but individual strains contain only a subset of the cerevisiae genes. We identified S. cerevisiae strains that contain all four cerevisiae 'lager-specific' genes, and distinct patterns of loss of these genes in other strains. Analysis of the subtelomeric regions uncovered patterns of loss in different S. cerevisiae strains. We identify two classes of S. cerevisiae strains: ale yeasts (Foster O) and stout yeasts with patterns of 'lager-specific' genes and subtelomeric regions identical to Group I and II S. pastorianus yeasts, respectively. These findings lead us to propose that Group I and II S. pastorianus strains originate from separate hybridization events involving different S. cerevisiae lineages. Using the combined bioinformatic and PCR data, we describe a potential classification map for industrial yeasts. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.

  5. Glucose repression in Saccharomyces cerevisiae.

    PubMed

    Kayikci, Ömur; Nielsen, Jens

    2015-09-01

    Glucose is the primary source of energy for the budding yeast Saccharomyces cerevisiae. Although yeast cells can utilize a wide range of carbon sources, presence of glucose suppresses molecular activities involved in the use of alternate carbon sources as well as it represses respiration and gluconeogenesis. This dominant effect of glucose on yeast carbon metabolism is coordinated by several signaling and metabolic interactions that mainly regulate transcriptional activity but are also effective at post-transcriptional and post-translational levels. This review describes effects of glucose repression on yeast carbon metabolism with a focus on roles of the Snf3/Rgt2 glucose-sensing pathway and Snf1 signal transduction in establishment and relief of glucose repression. © FEMS 2015.

  6. Structure of the tandem PX-PH domains of Bem3 from Saccharomyces cerevisiae.

    PubMed

    Ali, Imtiaz; Eu, Sungmin; Koch, Daniel; Bleimling, Nathalie; Goody, Roger S; Müller, Matthias P

    2018-05-01

    The structure of the tandem lipid-binding PX and pleckstrin-homology (PH) domains of the Cdc42 GTPase-activating protein Bem3 from Saccharomyces cerevisiae (strain S288c) has been determined to a resolution of 2.2 Å (R work = 21.1%, R free = 23.4%). It shows that the domains adopt a relative orientation that enables them to simultaneously bind to a membrane and suggests possible cooperativity in membrane binding. open access.

  7. Structure of the tandem PX-PH domains of Bem3 from Saccharomyces cerevisiae

    PubMed Central

    Ali, Imtiaz; Eu, Sungmin; Bleimling, Nathalie

    2018-01-01

    The structure of the tandem lipid-binding PX and pleckstrin-homology (PH) domains of the Cdc42 GTPase-activating protein Bem3 from Saccharomyces cerevisiae (strain S288c) has been determined to a resolution of 2.2 Å (R work = 21.1%, R free = 23.4%). It shows that the domains adopt a relative orientation that enables them to simultaneously bind to a membrane and suggests possible cooperativity in membrane binding. PMID:29718000

  8. Enhanced ethanol fermentation by engineered Saccharomyces cerevisiae strains with high spermidine contents.

    PubMed

    Kim, Sun-Ki; Jo, Jung-Hyun; Jin, Yong-Su; Seo, Jin-Ho

    2017-05-01

    Construction of robust and efficient yeast strains is a prerequisite for commercializing a biofuel production process. We have demonstrated that high intracellular spermidine (SPD) contents in Saccharomyces cerevisiae can lead to improved tolerance against various fermentation inhibitors, including furan derivatives and acetic acid. In this study, we examined the potential applicability of the S. cerevisiae strains with high SPD contents under two cases of ethanol fermentation: glucose fermentation in repeated-batch fermentations and xylose fermentation in the presence of fermentation inhibitors. During the sixteen times of repeated-batch fermentations using glucose as a sole carbon source, the S. cerevisiae strains with high SPD contents maintained higher cell viability and ethanol productivities than a control strain with lower SPD contents. Specifically, at the sixteenth fermentation, the ethanol productivity of a S. cerevisiae strain with twofold higher SPD content was 31% higher than that of the control strain. When the SPD content was elevated in an engineered S. cerevisiae capable of fermenting xylose, the resulting S. cerevisiae strain exhibited much 40-50% higher ethanol productivities than the control strain during the fermentations of synthetic hydrolysate containing high concentrations of fermentation inhibitors. These results suggest that the strain engineering strategy to increase SPD content is broadly applicable for engineering yeast strains for robust and efficient production of ethanol.

  9. [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.

  10. Global mapping of DNA conformational flexibility on Saccharomyces cerevisiae.

    PubMed

    Menconi, Giulia; Bedini, Andrea; Barale, Roberto; Sbrana, Isabella

    2015-04-01

    In this study we provide the first comprehensive map of DNA conformational flexibility in Saccharomyces cerevisiae complete genome. Flexibility plays a key role in DNA supercoiling and DNA/protein binding, regulating DNA transcription, replication or repair. Specific interest in flexibility analysis concerns its relationship with human genome instability. Enrichment in flexible sequences has been detected in unstable regions of human genome defined fragile sites, where genes map and carry frequent deletions and rearrangements in cancer. Flexible sequences have been suggested to be the determinants of fragile gene proneness to breakage; however, their actual role and properties remain elusive. Our in silico analysis carried out genome-wide via the StabFlex algorithm, shows the conserved presence of highly flexible regions in budding yeast genome as well as in genomes of other Saccharomyces sensu stricto species. Flexibile peaks in S. cerevisiae identify 175 ORFs mapping on their 3'UTR, a region affecting mRNA translation, localization and stability. (TA)n repeats of different extension shape the central structure of peaks and co-localize with polyadenylation efficiency element (EE) signals. ORFs with flexible peaks share common features. Transcripts are characterized by decreased half-life: this is considered peculiar of genes involved in regulatory systems with high turnover; consistently, their function affects biological processes such as cell cycle regulation or stress response. Our findings support the functional importance of flexibility peaks, suggesting that the flexible sequence may be derived by an expansion of canonical TAYRTA polyadenylation efficiency element. The flexible (TA)n repeat amplification could be the outcome of an evolutionary neofunctionalization leading to a differential 3'-end processing and expression regulation in genes with peculiar function. Our study provides a new support to the functional role of flexibility in genomes and a

  11. Global Mapping of DNA Conformational Flexibility on Saccharomyces cerevisiae

    PubMed Central

    Menconi, Giulia; Bedini, Andrea; Barale, Roberto; Sbrana, Isabella

    2015-01-01

    In this study we provide the first comprehensive map of DNA conformational flexibility in Saccharomyces cerevisiae complete genome. Flexibility plays a key role in DNA supercoiling and DNA/protein binding, regulating DNA transcription, replication or repair. Specific interest in flexibility analysis concerns its relationship with human genome instability. Enrichment in flexible sequences has been detected in unstable regions of human genome defined fragile sites, where genes map and carry frequent deletions and rearrangements in cancer. Flexible sequences have been suggested to be the determinants of fragile gene proneness to breakage; however, their actual role and properties remain elusive. Our in silico analysis carried out genome-wide via the StabFlex algorithm, shows the conserved presence of highly flexible regions in budding yeast genome as well as in genomes of other Saccharomyces sensu stricto species. Flexibile peaks in S. cerevisiae identify 175 ORFs mapping on their 3’UTR, a region affecting mRNA translation, localization and stability. (TA)n repeats of different extension shape the central structure of peaks and co-localize with polyadenylation efficiency element (EE) signals. ORFs with flexible peaks share common features. Transcripts are characterized by decreased half-life: this is considered peculiar of genes involved in regulatory systems with high turnover; consistently, their function affects biological processes such as cell cycle regulation or stress response. Our findings support the functional importance of flexibility peaks, suggesting that the flexible sequence may be derived by an expansion of canonical TAYRTA polyadenylation efficiency element. The flexible (TA)n repeat amplification could be the outcome of an evolutionary neofunctionalization leading to a differential 3’-end processing and expression regulation in genes with peculiar function. Our study provides a new support to the functional role of flexibility in genomes and a

  12. Effect of Temperature on the Prevalence of Saccharomyces Non cerevisiae Species against a S. cerevisiae Wine Strain in Wine Fermentation: Competition, Physiological Fitness, and Influence in Final Wine Composition.

    PubMed

    Alonso-Del-Real, Javier; Lairón-Peris, María; Barrio, Eladio; Querol, Amparo

    2017-01-01

    Saccharomyces cerevisiae is the main microorganism responsible for the fermentation of wine. Nevertheless, in the last years wineries are facing new challenges due to current market demands and climate change effects on the wine quality. New yeast starters formed by non-conventional Saccharomyces species (such as S. uvarum or S. kudriavzevii ) or their hybrids ( S. cerevisiae x S. uvarum and S. cerevisiae x S. kudriavzevii ) can contribute to solve some of these challenges. They exhibit good fermentative capabilities at low temperatures, producing wines with lower alcohol and higher glycerol amounts. However, S . cerevisiae can competitively displace other yeast species from wine fermentations, therefore the use of these new starters requires an analysis of their behavior during competition with S. cerevisiae during wine fermentation. In the present study we analyzed the survival capacity of non- cerevisiae strains in competition with S. cerevisiae during fermentation of synthetic wine must at different temperatures. First, we developed a new method, based on QPCR, to quantify the proportion of different Saccharomyces yeasts in mixed cultures. This method was used to assess the effect of competition on the growth fitness. In addition, fermentation kinetics parameters and final wine compositions were also analyzed. We observed that some cryotolerant Saccharomyces yeasts, particularly S. uvarum , seriously compromised S. cerevisiae fitness during competences at lower temperatures, which explains why S. uvarum can replace S. cerevisiae during wine fermentations in European regions with oceanic and continental climates. From an enological point of view, mixed co-cultures between S. cerevisiae and S. paradoxus or S. eubayanus , deteriorated fermentation parameters and the final product composition compared to single S. cerevisiae inoculation. However, in co-inoculated synthetic must in which S. kudriavzevii or S. uvarum coexisted with S. cerevisiae , there were

  13. Effect of Temperature on the Prevalence of Saccharomyces Non cerevisiae Species against a S. cerevisiae Wine Strain in Wine Fermentation: Competition, Physiological Fitness, and Influence in Final Wine Composition

    PubMed Central

    Alonso-del-Real, Javier; Lairón-Peris, María; Barrio, Eladio; Querol, Amparo

    2017-01-01

    Saccharomyces cerevisiae is the main microorganism responsible for the fermentation of wine. Nevertheless, in the last years wineries are facing new challenges due to current market demands and climate change effects on the wine quality. New yeast starters formed by non-conventional Saccharomyces species (such as S. uvarum or S. kudriavzevii) or their hybrids (S. cerevisiae x S. uvarum and S. cerevisiae x S. kudriavzevii) can contribute to solve some of these challenges. They exhibit good fermentative capabilities at low temperatures, producing wines with lower alcohol and higher glycerol amounts. However, S. cerevisiae can competitively displace other yeast species from wine fermentations, therefore the use of these new starters requires an analysis of their behavior during competition with S. cerevisiae during wine fermentation. In the present study we analyzed the survival capacity of non-cerevisiae strains in competition with S. cerevisiae during fermentation of synthetic wine must at different temperatures. First, we developed a new method, based on QPCR, to quantify the proportion of different Saccharomyces yeasts in mixed cultures. This method was used to assess the effect of competition on the growth fitness. In addition, fermentation kinetics parameters and final wine compositions were also analyzed. We observed that some cryotolerant Saccharomyces yeasts, particularly S. uvarum, seriously compromised S. cerevisiae fitness during competences at lower temperatures, which explains why S. uvarum can replace S. cerevisiae during wine fermentations in European regions with oceanic and continental climates. From an enological point of view, mixed co-cultures between S. cerevisiae and S. paradoxus or S. eubayanus, deteriorated fermentation parameters and the final product composition compared to single S. cerevisiae inoculation. However, in co-inoculated synthetic must in which S. kudriavzevii or S. uvarum coexisted with S. cerevisiae, there were fermentation

  14. Identification and characterization of Saccharomyces cerevisiae strains isolated from West African sorghum beer.

    PubMed

    van der Aa Kühle, A; Jesperen, L; Glover, R L; Diawara, B; Jakobsen, M

    2001-08-01

    The occurrence and characterization of yeasts isolated from sorghum beer produced in Ghana and Burkina Faso, West Africa, were investigated. The yeasts involved in the fermentations were found to consist of Saccharomyces spp. almost exclusively. Of the isolates investigated, 45% were identified as Saccharomyces cerevisiae, whereas more than half of the isolates (53%) had physiological properties atypical of S. cerevisiae or any other member of the complex sensu strictu, as they were able to assimilate only glucose, maltose and ethanol as carbon sources. Both ITS-PCR RFLP and PFGE strongly indicated that these isolates were related to S. cerevisiae, regardless of their phenotypic characteristics. Sequencing of the D1/D2 domain of the 26S rDNA confirmed the close relatedness to S. cerevisiae with 0.5% nucleotide differences. The MAL1 and MAL3 loci were found for all isolates as the only recognized MAL loci. Besides, for 40% of the isolates the MAL61 probe hybridized to a position of about 950 kbp, which has not formerly been described as a MAL locus. The results showed that the spontaneous fermentation of West African sorghum beer is dominated by a variety of strains of S.cerevisiae not previously described, among which starter cultures should be selected. Copyright 2001 John Wiley & Sons, Ltd.

  15. Microaerobic glycerol formation in Saccharomyces cerevisiae.

    PubMed

    Costenoble, R; Valadi, H; Gustafsson, L; Niklasson, C; Franzén, C J

    2000-12-01

    The yeast Saccharomyces cerevisiae produces large amounts of glycerol as an osmoregulator during hyperosmotic stress and as a redox sink at low oxygen availability. NAD(+)-dependent glycerol-3-phosphate dehydrogenase in S. cerevisiae is present in two isoforms, coded for by two different genes, GPD1 and GPD2. Mutants for either one or both of these genes were investigated under carefully controlled static and dynamic conditions in continuous cultures at low oxygen transfer rates. Our results show that S. cerevisiae controls the production of glycerol in response to hypoxic conditions by regulating the expression of several genes. At high demand for NADH reoxidation, a strong induction was seen not only of the GPD2 gene, but also of GPP1, encoding one of the molecular forms of glycerol-3-phosphatase. Induction of the GPP1 gene appears to play a decisive role at elevated growth rates. At low demand for NADH reoxidation via glycerol formation, the GPD1, GPD2, GPP1, and GPP2 genes were all expressed at basal levels. The dynamics of the gene induction and the glycerol formation at low demand for NADH reoxidation point to an important role of the Gpd1p; deletion of the GPD1 gene strongly altered the expression patterns of the GPD2 and GPP1 genes under such conditions. Furthermore, our results indicate that GCY1 and DAK1, tentatively encoding glycerol dehydrogenase and dihydroxyacetone kinase, respectively, may be involved in the redox regulation of S. cerevisiae. Copyright 2000 John Wiley & Sons, Ltd.

  16. Transcriptomic analysis of Saccharomyces cerevisiae upon honokiol treatment.

    PubMed

    Zhu, Xiaolong; Zou, Shenshen; Li, Youbin; Liang, Yongheng

    2017-09-01

    Honokiol (HNK), one of the main medicinal components in Magnolia officinalis, possesses antimicrobial activity against a variety of pathogenic bacteria and fungi. However, little is known of the molecular mechanisms underpinning the antimicrobial activity. To explore the molecular mechanism of its antifungal activity, we determined the effects of HNK on the mRNA expression profile of Saccharomyces cerevisiae using a DNA microarray approach. HNK markedly induced the expression of genes related to iron uptake and homeostasis. Conversely, genes associated with respiratory electron transport were downregulated, mirroring the effects of iron starvation. Meanwhile, HNK-induced growth deficiency was partly rescued by iron supplementation and HNK reacted with iron, producing iron complexes that depleted iron. These results suggest that HNK treatment induced iron starvation. Additionally, HNK treatment resulted in the upregulation of genes involved in protein synthesis and drug resistance networks. Furthermore, the deletion of PDR5, a gene encoding the plasma membrane ATP binding cassette (ABC) transporter, conferred sensitivity to HNK. Overexpression of PDR5 enhanced resistance of WT and pdr5Δ strains to HNK. Taken together, these findings suggest that HNK, which can be excluded by overexpression of Pdr5, functions in multiple cellular processes in S. cerevisiae, particularly in inducing iron starvation to inhibit cell growth. Copyright © 2017 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  17. Mixing of vineyard and oak-tree ecotypes of Saccharomyces cerevisiae in North American vineyards.

    PubMed

    Hyma, Katie E; Fay, Justin C

    2013-06-01

    Humans have had a significant impact on the distribution and abundance of Saccharomyces cerevisiae through its widespread use in beer, bread and wine production. Yet, similar to other Saccharomyces species, S. cerevisiae has also been isolated from habitats unrelated to fermentations. Strains of S. cerevisiae isolated from grapes, wine must and vineyards worldwide are genetically differentiated from strains isolated from oak-tree bark, exudate and associated soil in North America. However, the causes and consequences of this differentiation have not yet been resolved. Historical differentiation of these two groups may have been influenced by geographic, ecological or human-associated barriers to gene flow. Here, we make use of the relatively recent establishment of vineyards across North America to identify and characterize any active barriers to gene flow between these two groups. We examined S. cerevisiae strains isolated from grapes and oak trees within three North American vineyards and compared them to those isolated from oak trees outside of vineyards. Within vineyards, we found evidence of migration between grapes and oak trees and potential gene flow between the divergent oak-tree and vineyard groups. Yet, we found no vineyard genotypes on oak trees outside of vineyards. In contrast, Saccharomyces paradoxus isolated from the same sources showed population structure characterized by isolation by distance. The apparent absence of ecological or genetic barriers between sympatric vineyard and oak-tree populations of S. cerevisiae implies that vineyards play an important role in the mixing between these two groups. © 2013 John Wiley & Sons Ltd.

  18. Comparative characterization of endo-polygalacturonase (Pgu1) from Saccharomyces cerevisiae and Saccharomyces paradoxus under winemaking conditions.

    PubMed

    Eschstruth, Alexis; Divol, Benoit

    2011-08-01

    Wine strains of Saccharomyces cerevisiae have no to weak natural pectinase activity, despite their genetic ability to secrete an endo-polygalacturonase. The addition of external pectinase of fungal origin has therefore become a common step of winemaking in order to enhance the extraction of compounds located in the grape berry skins during maceration and to ease wine clarification after maturation. Recently, the strong pectinase activity of a wine strain of Saccharomyces paradoxus has been reported. In this study, the endo-polygalacturonase-encoding gene of S. paradoxus was sequenced and its activity was characterised, compared with that of S. cerevisiae and tested under winemaking conditions through overexpression of both genes individually in S. cerevisiae. A few differences in the amino acids sequences between the two proteins were revealed and the activity of the Pgu1 enzyme of S. paradoxus was shown to be weaker under winemaking conditions. Clear indicators of extracellular activity were observed in the wines made with both recombinant strains (i.e. enzyme activity in cell-free wine, higher methanol concentration and higher free-run wine), but the actual composition of the wines fermented with the mutants was only sparingly altered. Although unexpectedly found in lower concentrations in the latter wines, phenolic compounds were shown to be the most discriminatory components. Overexpressing the PGU1 gene of S. paradoxus or that of S. cerevisiae did not make much difference, showing that the higher activity of S. paradoxus strains under laboratory conditions could be due to a different regulation mechanism rather than to a different sequence of PGU1.

  19. Catabolism of coniferyl aldehyde, ferulic acid and p-coumaric acid by Saccharomyces cerevisiae yields less toxic products.

    PubMed

    Adeboye, Peter Temitope; Bettiga, Maurizio; Aldaeus, Fredrik; Larsson, Per Tomas; Olsson, Lisbeth

    2015-09-21

    increased to 127 % of the control in the presence of p-coumaric acid. Coniferyl aldehyde, ferulic acid and p-coumaric acid and their conversion products were screened for inhibition, the conversion products were less inhibitory than coniferyl aldehyde, ferulic acid and p-coumaric acid, indicating that the conversion of the three compounds by Saccharomyces cerevisiae was also a detoxification process. We conclude that the conversion of coniferyl aldehyde, ferulic acid and p-coumaric acid into less inhibitory compounds is a form of stress response and a detoxification process. We hypothesize that all phenolic compounds are converted by Saccharomyces cerevisiae using the same metabolic process. We suggest that the enhancement of the ability of S. cerevisiae to convert toxic phenolic compounds into less inhibitory compounds is a potent route to developing a S. cerevisiae with superior tolerance to phenolic compounds.

  20. Functional equivalence of translation factor eIF5B from Candida albicans and Saccharomyces cerevisiae.

    PubMed

    Jun, Kyung Ok; Yang, Eun Ji; Lee, Byeong Jeong; Park, Jeong Ro; Lee, Joon H; Choi, Sang Ki

    2008-04-30

    Eukaryotic translation initiation factor 5B (eIF5B) plays a role in recognition of the AUG codon in conjunction with translation factor eIF2, and promotes joining of the 60S ribosomal subunit. To see whether the eIF5B proteins of other organisms function in Saccharomyces cerevisiae, we cloned the corresponding genes from Oryza sativa, Arabidopsis thaliana, Aspergillus nidulans and Candida albican and expressed them under the control of the galactose-inducible GAL promoter in the fun12Delta strain of Saccharomyces cerevisiae. Expression of Candida albicans eIF5B complemented the slow-growth phenotype of the fun12Delta strain, but that of Aspergillus nidulance did not, despite the fact that its protein was expressed better than that of Candida albicans. The Arabidopsis thaliana protein was also not functional in Saccharomyces. These results reveal that the eIF5B in Candida albicans has a close functional relationship with that of Sacharomyces cerevisiae, as also shown by a phylogenetic analysis based on the amino acid sequences of the eIF5Bs.

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

    ERIC Educational Resources Information Center

    Deutch, Charles E.; Marshall, Pamela A.

    2008-01-01

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

  2. Response of Saccharomyces cerevisiae to D-limonene-induced oxidative stress.

    PubMed

    Liu, Jidong; Zhu, Yibo; Du, Guocheng; Zhou, Jingwen; Chen, Jian

    2013-07-01

    In the present study, we investigated the mode of cell response induced by D-limonene in Saccharomyces cerevisiae. D-limonene treatment was found to be accompanied by intracellular accumulation of reactive oxygen species (ROS). Since ROS impair cell membranes, an engineered strain with enhanced membrane biosynthesis exhibited a higher tolerance to D-limonene. Subsequent addition of an ROS scavenger significantly reduced the ROS level and alleviated cell growth inhibition. Thus, D-limonene-induced ROS accumulation plays an important role in cell death in S. cerevisiae. In D-limonene-treated S. cerevisiae strains, higher levels of antioxidants, antioxidant enzymes, and nicotinamide adenine dinucleotide phosphate (NADPH) were synthesized. Quantitative real-time PCR results also verified that D-limonene treatment triggered upregulation of genes involved in the antioxidant system and the regeneration of NADPH at the transcription level in S. cerevisiae. These data indicate that D-limonene treatment results in intracellular ROS accumulation, an important factor in cell death, and several antioxidant mechanisms in S. cerevisiae were enhanced in response to D-limonene treatment.

  3. Omics analysis of acetic acid tolerance in Saccharomyces cerevisiae.

    PubMed

    Geng, Peng; Zhang, Liang; Shi, Gui Yang

    2017-05-01

    Acetic acid is an inhibitor in industrial processes such as wine making and bioethanol production from cellulosic hydrolysate. It causes energy depletion, inhibition of metabolic enzyme activity, growth arrest and ethanol productivity losses in Saccharomyces cerevisiae. Therefore, understanding the mechanisms of the yeast responses to acetic acid stress is essential for improving acetic acid tolerance and ethanol production. Although 329 genes associated with acetic acid tolerance have been identified in the Saccharomyces genome and included in the database ( http://www.yeastgenome.org/observable/resistance_to_acetic_acid/overview ), the cellular mechanistic responses to acetic acid remain unclear in this organism. Post-genomic approaches such as transcriptomics, proteomics, metabolomics and chemogenomics are being applied to yeast and are providing insight into the mechanisms and interactions of genes, proteins and other components that together determine complex quantitative phenotypic traits such as acetic acid tolerance. This review focuses on these omics approaches in the response to acetic acid in S. cerevisiae. Additionally, several novel strains with improved acetic acid tolerance have been engineered by modifying key genes, and the application of these strains and recently acquired knowledge to industrial processes is also discussed.

  4. Improved Xylose Metabolism by a CYC8 Mutant of Saccharomyces cerevisiae.

    PubMed

    Nijland, Jeroen G; Shin, Hyun Yong; Boender, Leonie G M; de Waal, Paul P; Klaassen, Paul; Driessen, Arnold J M

    2017-06-01

    Engineering Saccharomyces cerevisiae for the utilization of pentose sugars is an important goal for the production of second-generation bioethanol and biochemicals. However, S. cerevisiae lacks specific pentose transporters, and in the presence of glucose, pentoses enter the cell inefficiently via endogenous hexose transporters (HXTs). By means of in vivo engineering, we have developed a quadruple hexokinase deletion mutant of S. cerevisiae that evolved into a strain that efficiently utilizes d-xylose in the presence of high d-glucose concentrations. A genome sequence analysis revealed a mutation (Y353C) in the general corepressor CYC8 , or SSN6 , which was found to be responsible for the phenotype when introduced individually in the nonevolved strain. A transcriptome analysis revealed altered expression of 95 genes in total, including genes involved in (i) hexose transport, (ii) maltose metabolism, (iii) cell wall function (mannoprotein family), and (iv) unknown functions (seripauperin multigene family). Of the 18 known HXTs, genes for 9 were upregulated, especially the low or nonexpressed HXT10 , HXT13 , HXT15 , and HXT16 Mutant cells showed increased uptake rates of d-xylose in the presence of d-glucose, as well as elevated maximum rates of metabolism ( V max ) for both d-glucose and d-xylose transport. The data suggest that the increased expression of multiple hexose transporters renders d-xylose metabolism less sensitive to d-glucose inhibition due to an elevated transport rate of d-xylose into the cell. IMPORTANCE The yeast Saccharomyces cerevisiae is used for second-generation bioethanol formation. However, growth on xylose is limited by pentose transport through the endogenous hexose transporters (HXTs), as uptake is outcompeted by the preferred substrate, glucose. Mutant strains were obtained with improved growth characteristics on xylose in the presence of glucose, and the mutations mapped to the regulator Cyc8. The inactivation of Cyc8 caused increased

  5. Ecological Success of a Group of Saccharomyces cerevisiae/Saccharomyces kudriavzevii Hybrids in the Northern European Wine-Making Environment

    PubMed Central

    Erny, C.; Raoult, P.; Alais, A.; Butterlin, G.; Delobel, P.; Matei-Radoi, F.; Casaregola, S.

    2012-01-01

    The hybrid nature of lager-brewing yeast strains has been known for 25 years; however, yeast hybrids have only recently been described in cider and wine fermentations. In this study, we characterized the hybrid genomes and the relatedness of the Eg8 industrial yeast strain and of 24 Saccharomyces cerevisiae/Saccharomyces kudriavzevii hybrid yeast strains used for wine making in France (Alsace), Germany, Hungary, and the United States. An array-based comparative genome hybridization (aCGH) profile of the Eg8 genome revealed a typical chimeric profile. Measurement of hybrids DNA content per cell by flow cytometry revealed multiple ploidy levels (2n, 3n, or 4n), and restriction fragment length polymorphism analysis of 22 genes indicated variable amounts of S. kudriavzevii genetic content in three representative strains. We developed microsatellite markers for S. kudriavzevii and used them to analyze the diversity of a population isolated from oaks in Ardèche (France). This analysis revealed new insights into the diversity of this species. We then analyzed the diversity of the wine hybrids for 12 S. cerevisiae and 7 S. kudriavzevii microsatellite loci and found that these strains are the products of multiple hybridization events between several S. cerevisiae wine yeast isolates and various S. kudriavzevii strains. The Eg8 lineage appeared remarkable, since it harbors strains found over a wide geographic area, and the interstrain divergence measured with a (δμ)2 genetic distance indicates an ancient origin. These findings reflect the specific adaptations made by S. cerevisiae/S. kudriavzevii cryophilic hybrids to winery environments in cool climates. PMID:22344648

  6. Clinical Saccharomyces cerevisiae isolates cannot cross the epithelial barrier in vitro.

    PubMed

    Pérez-Torrado, Roberto; Llopis, Silvia; Jespersen, Lene; Fernández-Espinar, Teresa; Querol, Amparo

    2012-06-15

    Saccharomyces cerevisiae is generally considered to be a safe organism and is essential to produce many different kinds of foods as well as being widely used as a dietary supplement. However, several isolates, which are genetically related to brewing and baking yeasts, have shown virulent traits, being able to produce human infections in immunodeficient patients. Previously it has been shown that the administration of S. cerevisiae clinical isolates can lead to systemic infections, reaching several organs in murine systems. In this work, we studied S. cerevisiae clinical isolates in an in vitro intestinal epithelial barrier model, comparing their behaviour with that of several strains of the related pathogens Candida glabrata and Candida albicans. The results showed that, in contrast to C. glabrata and C. albicans, S. cerevisiae was not able to cross the intestinal barrier. We concluded that S. cerevisiae can only perform opportunistic or passive crossings when epithelial barrier integrity is previously compromised. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Oral administration of myostatin-specific recombinant Saccharomyces cerevisiae vaccine in rabbit.

    PubMed

    Liu, Zhongtian; Zhou, Gang; Ren, Chonghua; Xu, Kun; Yan, Qiang; Li, Xinyi; Zhang, Tingting; Zhang, Zhiying

    2016-04-29

    Yeast is considered as a simple and cost-effective host for protein expression, and our previous studies have proved that Saccharomyces cerevisiae can deliver recombinant protein and DNA into mouse dendritic cells and can further induce immune responses as novel vaccines. In order to know whether similar immune responses can be induced in rabbit by oral administration of such recombinant S. cerevisiae vaccine, we orally fed the rabbits with heat-inactivated myostatin-recombinant S. cerevisiae for 5 weeks, and then myostatin-specific antibody in serum was detected successfully by western blotting and ELISA assay. The rabbits treated with myostatin-recombinant S. cerevisiae vaccine grew faster and their muscles were much heavier than that of the control group. As a common experimental animal and a meat livestock with great economic value, rabbit was proved to be the second animal species that have been successfully orally immunized by recombinant S. cerevisiae vaccine after mice. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Repurposing the Saccharomyces cerevisiae peroxisome for compartmentalizing multi-enzyme pathways

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

    DeLoache, William; Russ, Zachary; Samson, Jennifer

    The peroxisome of Saccharomyces cerevisiae was targeted for repurposing in order to create a synthetic organelle that provides a generalizable compartment for engineered metabolic pathways. Compartmentalization of enzymes into organelles is a promising strategy for limiting metabolic crosstalk, improving pathway efficiency, and ultimately modifying the chemical environment to be distinct from that of the cytoplasm. We focused on the Saccharomyces cerevisiae peroxisome, as this organelle is not required for viability when grown on conventional media. We identified an enhanced peroxisomal targeting signal type 1 (PTS1) for rapidly importing non-native cargo proteins. Additionally, we performed the first systematic in vivo measurementsmore » of nonspecific metabolite permeability across the peroxisomal membrane using a polymer exclusion assay and characterized the size dependency of metabolite trafficking. Finally, we applied these new insights to compartmentalize a two-enzyme pathway in the peroxisome and characterize the expression regimes where compartmentalization leads to improved product titer. This work builds a foundation for using the peroxisome as a synthetic organelle, highlighting both promise and future challenges on the way to realizing this goal.« less

  9. Sucrose and Saccharomyces cerevisiae: a relationship most sweet.

    PubMed

    Marques, Wesley Leoricy; Raghavendran, Vijayendran; Stambuk, Boris Ugarte; Gombert, Andreas Karoly

    2016-02-01

    Sucrose is an abundant, readily available and inexpensive substrate for industrial biotechnology processes and its use is demonstrated with much success in the production of fuel ethanol in Brazil. Saccharomyces cerevisiae, which naturally evolved to efficiently consume sugars such as sucrose, is one of the most important cell factories due to its robustness, stress tolerance, genetic accessibility, simple nutrient requirements and long history as an industrial workhorse. This minireview is focused on sucrose metabolism in S. cerevisiae, a rather unexplored subject in the scientific literature. An analysis of sucrose availability in nature and yeast sugar metabolism was performed, in order to understand the molecular background that makes S. cerevisiae consume this sugar efficiently. A historical overview on the use of sucrose and S. cerevisiae by humans is also presented considering sugarcane and sugarbeet as the main sources of this carbohydrate. Physiological aspects of sucrose consumption are compared with those concerning other economically relevant sugars. Also, metabolic engineering efforts to alter sucrose catabolism are presented in a chronological manner. In spite of its extensive use in yeast-based industries, a lot of basic and applied research on sucrose metabolism is imperative, mainly in fields such as genetics, physiology and metabolic engineering. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. Sporulation in the Budding Yeast Saccharomyces cerevisiae

    PubMed Central

    Neiman, Aaron M.

    2011-01-01

    In response to nitrogen starvation in the presence of a poor carbon source, diploid cells of the yeast Saccharomyces cerevisiae undergo meiosis and package the haploid nuclei produced in meiosis into spores. The formation of spores requires an unusual cell division event in which daughter cells are formed within the cytoplasm of the mother cell. This process involves the de novo generation of two different cellular structures: novel membrane compartments within the cell cytoplasm that give rise to the spore plasma membrane and an extensive spore wall that protects the spore from environmental insults. This article summarizes what is known about the molecular mechanisms controlling spore assembly with particular attention to how constitutive cellular functions are modified to create novel behaviors during this developmental process. Key regulatory points on the sporulation pathway are also discussed as well as the possible role of sporulation in the natural ecology of S. cerevisiae. PMID:22084423

  11. Molecular cloning and expression in Saccharomyces cerevisiae and Neurospora crassa of the invertase gene from Neurospora crassa.

    PubMed

    Carú, M; Cifuentes, V; Pincheira, G; Jiménez, A

    1989-10-01

    A plasmid (named pCN2) carrying a 7.6 kb BamHI DNA insert was isolated from a Neurospora crassa genomic library raised in the yeast vector YRp7. Saccharomyces cerevisiae suco and N. crassa inv strains transformed with pNC2 were able to grow on sucrose-based media and expressed invertase activity. Saccharomyces cerevisiae suco (pNC2) expressed a product which immunoreacted with antibody raised against purified invertase from wild type N. crassa, although S. cerevisiae suc+ did not. The cloned DNA hybridized with a 7.6 kb DNA fragment from BamHI-restricted wild type N. crassa DNA. Plasmid pNC2 transformed N. crassa Inv- to Inv+ by integration either near to the endogenous inv locus (40% events) or at other genomic sites (60% events). It appears therefore that the cloned DNA piece encodes the N. crassa invertase enzyme. A 3.8 kb XhoI DNA fragment, derived from pNC2, inserted in YRp7, in both orientation, was able to express invertase activity in yeast, suggesting that it contains an intact invertase gene which is not expressed from a vector promoter.

  12. Genomic reconstruction to improve bioethanol and ergosterol production of industrial yeast Saccharomyces cerevisiae.

    PubMed

    Zhang, Ke; Tong, Mengmeng; Gao, Kehui; Di, Yanan; Wang, Pinmei; Zhang, Chunfang; Wu, Xuechang; Zheng, Daoqiong

    2015-02-01

    Baker's yeast (Saccharomyces cerevisiae) is the common yeast used in the fields of bread making, brewing, and bioethanol production. Growth rate, stress tolerance, ethanol titer, and byproducts yields are some of the most important agronomic traits of S. cerevisiae for industrial applications. Here, we developed a novel method of constructing S. cerevisiae strains for co-producing bioethanol and ergosterol. The genome of an industrial S. cerevisiae strain, ZTW1, was first reconstructed through treatment with an antimitotic drug followed by sporulation and hybridization. A total of 140 mutants were selected for ethanol fermentation testing, and a significant positive correlation between ergosterol content and ethanol production was observed. The highest performing mutant, ZG27, produced 7.9 % more ethanol and 43.2 % more ergosterol than ZTW1 at the end of fermentation. Chromosomal karyotyping and proteome analysis of ZG27 and ZTW1 suggested that this breeding strategy caused large-scale genome structural variations and global gene expression diversities in the mutants. Genetic manipulation further demonstrated that the altered expression activity of some genes (such as ERG1, ERG9, and ERG11) involved in ergosterol synthesis partly explained the trait improvement in ZG27.

  13. Epidemiological Investigation of Vaginal Saccharomyces cerevisiae Isolates by a Genotypic Method

    PubMed Central

    McCullough, Michael J.; Clemons, Karl V.; Farina, Claudio; McCusker, John H.; Stevens, David A.

    1998-01-01

    Saccharomyces cerevisiae is a ubiquitous, ascomycetous yeast, and vaginitis caused by this organism has been reported only very rarely. The aim of the present investigation was to assess the epidemiological relatedness of a group of vaginal and commercial S. cerevisiae isolates by a previously reported genetic typing method, which divided the isolates into two broad groups with numerous subtypes. Nineteen S. cerevisiae isolates obtained from patients suffering from vaginitis and four isolates from commercial products in the same city were analyzed. The cellular DNA from each isolate was digested with the restriction endonuclease EcoRI, and restriction fragment length polymorphisms were generated by horizontal gel electrophoresis. The results showed that although vaginal isolates did not cluster in any particular genetic subtype, multiple patients were infected with indistinguishable strains (there were nine distinct strains among 23 isolates). For two of three patients, all three with two episodes of S. cerevisiae vaginitis, different strains were isolated during the recurrence of this disease. Three other patients with indistinguishable isolates were epidemiologically related in that two were practitioners in the same clinic and the third was a patient at this clinic. We also found that one commercial strain was indistinguishable from the strain isolated from three different women at the time that they were suffering from vaginitis. The findings of the present study suggest that some S. cerevisiae strains may possess properties permitting persistence in the human host. Furthermore, person-to-person contact and the proliferation of the use of S. cerevisiae as a health-food product, in home baking, and in home brewing may be a contributing factor in human colonization and infection with this organism. PMID:9466776

  14. High hydrostatic pressure and the cell membrane: stress response of Saccharomyces cerevisiae.

    PubMed

    Bravim, Fernanda; de Freitas, Jéssica M; Fernandes, A Alberto R; Fernandes, Patricia M B

    2010-02-01

    The brewing and baking yeast Saccharomyces cerevisiae is a useful eukaryotic model of stress response systems whose study could lead to the understanding of stress response mechanisms in other organisms. High hydrostatic pressure (HHP) exerts broad effects upon yeast cells, interfering with cell membranes, cellular architecture, and the processes of polymerization and denaturation of proteins. In this review, we focus on the effect of HHP on the S. cerevisiae cell membrane and describe the main signaling pathways involved in the pressure response.

  15. [Saccharomyces cerevisiae invasive infection: The first reported case in Morocco].

    PubMed

    Maleb, A; Sebbar, E; Frikh, M; Boubker, S; Moussaoui, A; El Mekkaoui, A; Khannoussi, W; Kharrasse, G; Belefquih, B; Lemnouer, A; Ismaili, Z; Elouennass, M

    2017-06-01

    Saccharomyces cerevisiae is a cosmopolitan yeast, widely used in agro-alimentary and pharmaceutical industry. Its impact in human pathology is rare, but maybe still underestimated compared to the real situation. This yeast is currently considered as an emerging and opportunistic pathogen. Risk factors are immunosuppression and intravascular device carrying. Fungemias are the most frequent clinical forms. We report the first case of S. cerevisiae invasive infection described in Morocco, and to propose a review of the literature cases of S. cerevisiae infections described worldwide. A 77-year-old patient, with no notable medical history, who was hospitalized for a upper gastrointestinal stenosis secondary to impassable metastatic gastric tumor. Its history was marked by the onset of septic shock, with S. cerevisiae in his urine and in his blood, with arguments for confirmation of invasion: the presence of several risk factors in the patient, positive direct microbiological examination, abundant and exclusive culture of S. cerevisiae from clinical samples. Species identification was confirmed by the study of biochemical characteristics of the isolated yeast. Confirmation of S. cerevisiae infection requires a clinical suspicion in patients with risk factors, but also a correct microbiological diagnosis. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  16. Local Nanomechanical Motion of the Cell Wall of Saccharomyces cerevisiae

    NASA Astrophysics Data System (ADS)

    Pelling, Andrew E.; Sehati, Sadaf; Gralla, Edith B.; Valentine, Joan S.; Gimzewski, James K.

    2004-08-01

    We demonstrate that the cell wall of living Saccharomyces cerevisiae (baker's yeast) exhibits local temperature-dependent nanomechanical motion at characteristic frequencies. The periodic motions in the range of 0.8 to 1.6 kHz with amplitudes of ~3 nm were measured using the cantilever of an atomic force microscope (AFM). Exposure of the cells to a metabolic inhibitor causes the periodic motion to cease. From the strong frequency dependence on temperature, we derive an activation energy of 58 kJ/mol, which is consistent with the cell's metabolism involving molecular motors such as kinesin, dynein, and myosin. The magnitude of the forces observed (~10 nN) suggests concerted nanomechanical activity is operative in the cell.

  17. Transcriptional Regulatory Networks in Saccharomyces cerevisiae

    NASA Astrophysics Data System (ADS)

    Lee, Tong Ihn; Rinaldi, Nicola J.; Robert, François; Odom, Duncan T.; Bar-Joseph, Ziv; Gerber, Georg K.; Hannett, Nancy M.; Harbison, Christopher T.; Thompson, Craig M.; Simon, Itamar; Zeitlinger, Julia; Jennings, Ezra G.; Murray, Heather L.; Gordon, D. Benjamin; Ren, Bing; Wyrick, John J.; Tagne, Jean-Bosco; Volkert, Thomas L.; Fraenkel, Ernest; Gifford, David K.; Young, Richard A.

    2002-10-01

    We have determined how most of the transcriptional regulators encoded in the eukaryote Saccharomyces cerevisiae associate with genes across the genome in living cells. Just as maps of metabolic networks describe the potential pathways that may be used by a cell to accomplish metabolic processes, this network of regulator-gene interactions describes potential pathways yeast cells can use to regulate global gene expression programs. We use this information to identify network motifs, the simplest units of network architecture, and demonstrate that an automated process can use motifs to assemble a transcriptional regulatory network structure. Our results reveal that eukaryotic cellular functions are highly connected through networks of transcriptional regulators that regulate other transcriptional regulators.

  18. Comprehensive quantitative analysis of central carbon and amino-acid metabolism in Saccharomyces cerevisiae under multiple conditions by targeted proteomics

    PubMed Central

    Costenoble, Roeland; Picotti, Paola; Reiter, Lukas; Stallmach, Robert; Heinemann, Matthias; Sauer, Uwe; Aebersold, Ruedi

    2011-01-01

    Decades of biochemical research have identified most of the enzymes that catalyze metabolic reactions in the yeast Saccharomyces cerevisiae. The adaptation of metabolism to changing nutritional conditions, in contrast, is much less well understood. As an important stepping stone toward such understanding, we exploit the power of proteomics assays based on selected reaction monitoring (SRM) mass spectrometry to quantify abundance changes of the 228 proteins that constitute the central carbon and amino-acid metabolic network in the yeast Saccharomyces cerevisiae, at five different metabolic steady states. Overall, 90% of the targeted proteins, including families of isoenzymes, were consistently detected and quantified in each sample, generating a proteomic data set that represents a nutritionally perturbed biological system at high reproducibility. The data set is near comprehensive because we detect 95–99% of all proteins that are required under a given condition. Interpreted through flux balance modeling, the data indicate that S. cerevisiae retains proteins not necessarily used in a particular environment. Further, the data suggest differential functionality for several metabolic isoenzymes. PMID:21283140

  19. Bioconversion of lignocellulose-derived sugars to ethanol by engineered Saccharomyces cerevisiae.

    PubMed

    Madhavan, Anjali; Srivastava, Aradhana; Kondo, Akihiko; Bisaria, Virendra S

    2012-03-01

    Lignocellulosic biomass from agricultural and agro-industrial residues represents one of the most important renewable resources that can be utilized for the biological production of ethanol. The yeast Saccharomyces cerevisiae is widely used for the commercial production of bioethanol from sucrose or starch-derived glucose. While glucose and other hexose sugars like galactose and mannose can be fermented to ethanol by S. cerevisiae, the major pentose sugars D-xylose and L-arabinose remain unutilized. Nevertheless, D-xylulose, the keto isomer of xylose, can be fermented slowly by the yeast and thus, the incorporation of functional routes for the conversion of xylose and arabinose to xylulose or xylulose-5-phosphate in Saccharomyces cerevisiae can help to improve the ethanol productivity and make the fermentation process more cost-effective. Other crucial bottlenecks in pentose fermentation include low activity of the pentose phosphate pathway enzymes and competitive inhibition of xylose and arabinose transport into the cell cytoplasm by glucose and other hexose sugars. Along with a brief introduction of the pretreatment of lignocellulose and detoxification of the hydrolysate, this review provides an updated overview of (a) the key steps involved in the uptake and metabolism of the hexose sugars: glucose, galactose, and mannose, together with the pentose sugars: xylose and arabinose, (b) various factors that play a major role in the efficient fermentation of pentose sugars along with hexose sugars, and (c) the approaches used to overcome the metabolic constraints in the production of bioethanol from lignocellulose-derived sugars by developing recombinant S. cerevisiae strains.

  20. The uptake of different iron salts by the yeast Saccharomyces cerevisiae

    PubMed Central

    Gaensly, Fernanda; Picheth, Geraldo; Brand, Debora; Bonfim, Tania M.B.

    2014-01-01

    Yeasts can be enriched with microelements, including iron; however, special physicochemical conditions are required to formulate a culture media that promotes both yeast growth and iron uptake. Different iron sources do not affect biomass formation; however, considering efficacy, cost, stability, and compatibility with Saccharomyces cerevisiae metabolism, ferrous sulphate is recommended. PMID:25242932

  1. PRIMARY STRUCTURE OF THE P450 LANOSTEROL DEMETHYLASE GENE FROM SACCHAROMYCES CEREVISIAE

    EPA Science Inventory

    We have sequenced the structural gene and flanking regions for lanosterol 14 alpha-demethylase (14DM) from Saccharomyces cerevisiae. An open reading frame of 530 codons encodes a 60.7-kDa protein. When this gene is disrupted by integrative transformation, the resulting strain req...

  2. TPS1 terminator increases mRNA and protein yield in a Saccharomyces cerevisiae expression system.

    PubMed

    Yamanishi, Mamoru; Katahira, Satoshi; Matsuyama, Takashi

    2011-01-01

    Both terminators and promoters regulate gene expression. In Saccharomyces cerevisiae, the TPS1 terminator (TPS1t), coupled to a gene encoding a fluorescent protein, produced more transgenic mRNA and protein than did similar constructs containing other terminators, such as CYC1t, TDH3t, and PGK1t. This suggests that TPS1t can be used as a general terminator in the development of metabolically engineered yeast in high-yield systems.

  3. Copper/Zinc-Superoxide Dismutase Is Required for Oxytetracycline Resistance of Saccharomyces cerevisiae

    PubMed Central

    Avery, Simon V.; Malkapuram, Srividya; Mateus, Carolina; Babb, Kimberly S.

    2000-01-01

    Saccharomyces cerevisiae, along with other eukaryotes, is resistant to tetracyclines. We found that deletion of SOD1 (encoding Cu/Zn superoxide dismutase) rendered S. cerevisiae hypersensitive to oxytetracycline (OTC): a sod1Δ mutant exhibited a >95% reduction in colony-forming ability at an OTC concentration of 20 μg ml−1, whereas concentrations of up to 1,000 μg ml−1 had no effect on the growth of the wild type. OTC resistance was restored in the sod1Δ mutant by complementation with wild-type SOD1. The effect of OTC appeared to be cytotoxic and was not evident in a ctt1Δ (cytosolic catalase) mutant or in the presence of tetracycline. SOD1 transcription was not induced by OTC, suggesting that constitutive SOD1 expression is sufficient for wild-type OTC resistance. OTC uptake levels in wild-type and sod1Δ strains were similar. However, lipid peroxidation and protein oxidation were both enhanced during exposure of the sod1Δ mutant, but not the wild type, to OTC. We propose that Sod1p protects S. cerevisiae against a mode of OTC action that is dependent on oxidative damage. PMID:10613865

  4. Energetic and metabolic transient response of Saccharomyces cerevisiae to benzoic acid.

    PubMed

    Kresnowati, M T A P; van Winden, W A; van Gulik, W M; Heijnen, J J

    2008-11-01

    Saccharomyces cerevisiae is known to be able to adapt to the presence of the commonly used food preservative benzoic acid with a large energy expenditure. Some mechanisms for the adaptation process have been suggested, but its quantitative energetic and metabolic aspects have rarely been discussed. This study discusses use of the stimulus response approach to quantitatively study the energetic and metabolic aspects of the transient adaptation of S. cerevisiae to a shift in benzoic acid concentration, from 0 to 0.8 mM. The information obtained also serves as the basis for further utilization of benzoic acid as a tool for targeted perturbation of the energy system, which is important in studying the kinetics and regulation of central carbon metabolism in S. cerevisiae. Using this experimental set-up, we found significant fast-transient (< 3000 s) increases in O(2) consumption and CO(2) production rates, of approximately 50%, which reflect a high energy requirement for the adaptation process. We also found that with a longer exposure time to benzoic acid, S. cerevisiae decreases the cell membrane permeability for this weak acid by a factor of 10 and decreases the cell size to approximately 80% of the initial value. The intracellular metabolite profile in the new steady-state indicates increases in the glycolytic and tricarboxylic acid cycle fluxes, which are in agreement with the observed increases in specific glucose and O(2) uptake rates.

  5. Single Cell Protein Production by Saccharomyces cerevisiae Using an Optimized Culture Medium Composition in a Batch Submerged Bioprocess.

    PubMed

    Hezarjaribi, Mehrnoosh; Ardestani, Fatemeh; Ghorbani, Hamid Reza

    2016-08-01

    Saccharomyces cerevisiae PTCC5269 growth was evaluated to specify an optimum culture medium to reach the highest protein production. Experiment design was conducted using a fraction of the full factorial methodology, and signal to noise ratio was used for results analysis. Maximum cell of 8.84 log (CFU/mL) was resulted using optimized culture composed of 0.3, 0.15, 1, and 50 g L(-1) of ammonium sulfate, iron sulfate, glycine, and glucose, respectively at 300 rpm and 35 °C. Glycine concentration (39.32 % contribution) and glucose concentration (36.15 % contribution) were determined as the most effective factors on the biomass production, while Saccharomyces cerevisiae growth had showed the least dependence on ammonium sulfate (5.2 % contribution) and iron sulfate (19.28 % contribution). The most interaction was diagnosed between ammonium sulfate and iron sulfate concentrations with interaction severity index of 50.71 %, while the less one recorded for glycine and glucose concentration was equal to 8.12 %. An acceptable consistency of 84.26 % was obtained between optimum theoretical cell numbers determined by software of 8.91 log (CFU/mL), and experimentally measured one at optimal condition confirms the suitability of the applied method. High protein content of 44.6 % using optimum culture suggests that Saccharomyces cerevisiae is a good commercial case for single cell protein production.

  6. Investigation of the Best Saccharomyces cerevisiae Growth Condition.

    PubMed

    Salari, Roshanak; Salari, Rosita

    2017-01-01

    Saccharomyces cerevisiae is known as one of the useful yeasts which are utilized in baking and other industries. It can be easily cultured at an economic price. Today the introduction of safe and efficient carriers is being considered. Due to its generally round shape, and the volume that is enclosed by its membrane and cell wall, it is used to encapsulate active materials to protect them from degradation or to introduce a sustained release drug delivery system. Providing the best conditions in order to achieve the best morphological properties of Saccharomyces cerevisiae as a carrier. In this research, the most suitable growth condition of yeast cells which provides the best size for use as drug carriers was found by a bioreactor in a synthetic culture medium. Yeast cell reproduction and growth curves were obtained, based on pour plate colony counting data and UV/Visible sample absorption at 600 nm. Yeast cell growth patterns and growth rates were determined by Matlab mathematical software. Results showed that pH=4 and dissolving oxygen (DO) 5% was the best condition for yeast cells to grow and reproduce. This condition also provided the largest size (2 × 3 μ) yeast cells. Owing to the yeast cells' low-cost production and their structural characteristics, they could be used as potent drug carriers. This work was supported by a grant from the Vice Chancellor of Research of Mashhad University of Medical Sciences.

  7. The new modern era of yeast genomics: community sequencing and the resulting annotation of multiple Saccharomyces cerevisiae strains at the Saccharomyces Genome Database

    PubMed Central

    Engel, Stacia R.; Cherry, J. Michael

    2013-01-01

    The first completed eukaryotic genome sequence was that of the yeast Saccharomyces cerevisiae, and the Saccharomyces Genome Database (SGD; http://www.yeastgenome.org/) is the original model organism database. SGD remains the authoritative community resource for the S. cerevisiae reference genome sequence and its annotation, and continues to provide comprehensive biological information correlated with S. cerevisiae genes and their products. A diverse set of yeast strains have been sequenced to explore commercial and laboratory applications, and a brief history of those strains is provided. The publication of these new genomes has motivated the creation of new tools, and SGD will annotate and provide comparative analyses of these sequences, correlating changes with variations in strain phenotypes and protein function. We are entering a new era at SGD, as we incorporate these new sequences and make them accessible to the scientific community, all in an effort to continue in our mission of educating researchers and facilitating discovery. Database URL: http://www.yeastgenome.org/ PMID:23487186

  8. Improved ethanol tolerance of Saccharomyces cerevisiae in mixed cultures with Kluyveromyces lactis on high-sugar fermentation.

    PubMed

    Yamaoka, Chizuru; Kurita, Osamu; Kubo, Tomoko

    2014-12-01

    The influence of non-Saccharomyces yeast, Kluyveromyces lactis, on metabolite formation and the ethanol tolerance of Saccharomyces cerevisiae in mixed cultures was examined on synthetic minimal medium containing 20% glucose. In the late stage of fermentation after the complete death of K. lactis, S. cerevisiae in mixed cultures was more ethanol-tolerant than that in pure culture. The chronological life span of S. cerevisiae was shorter in pure culture than mixed cultures. The yeast cells of the late stationary phase both in pure and mixed cultures had a low buoyant density with no significant difference in the non-quiescence state between both cultures. In mixed cultures, the glycerol contents increased and the alanine contents decreased when compared with the pure culture of S. cerevisiae. The distinctive intracellular amino acid pool concerning its amino acid concentrations and its amino acid composition was observed in yeast cells with different ethanol tolerance in the death phase. Co-cultivation of K. lactis seems to prompt S. cerevisiae to be ethanol tolerant by forming opportune metabolites such as glycerol and alanine and/or changing the intracellular amino acid pool. Copyright © 2014 Elsevier GmbH. All rights reserved.

  9. Preparation of cell-free splicing extracts from Saccharomyces cerevisiae.

    PubMed

    Ares, Manuel

    2013-10-01

    Much of our understanding of the mechanism of splicing comes from the analysis of cell extracts able to carry out splicing complex formation and splicing reactions in vitro using exogenously added synthetic model pre-mRNA transcripts. This protocol describes the preparation of whole-cell extracts from the budding yeast Saccharomyces cerevisiae. These extracts can be used to dissect the biochemical steps of the splicing reaction and to determine the macromolecules, cofactors, and substrate features necessary for successful splicing.

  10. The Oenological Potential of Hanseniaspora uvarum in Simultaneous and Sequential Co-fermentation with Saccharomyces cerevisiae for Industrial Wine Production

    PubMed Central

    Tristezza, Mariana; Tufariello, Maria; Capozzi, Vittorio; Spano, Giuseppe; Mita, Giovanni; Grieco, Francesco

    2016-01-01

    In oenology, the utilization of mixed starter cultures composed by Saccharomyces and non-Saccharomyces yeasts is an approach of growing importance for winemakers in order to enhance sensory quality and complexity of the final product without compromising the general quality and safety of the oenological products. In fact, several non-Saccharomyces yeasts are already commercialized as oenological starter cultures to be used in combination with Saccharomyces cerevisiae, while several others are the subject of various studies to evaluate their application. Our aim, in this study was to assess, for the first time, the oenological potential of H. uvarum in mixed cultures (co-inoculation) and sequential inoculation with S. cerevisiae for industrial wine production. Three previously characterized H. uvarum strains were separately used as multi-starter together with an autochthonous S. cerevisiae starter culture in lab-scale micro-vinification trials. On the basis of microbial development, fermentation kinetics and secondary compounds formation, the strain H. uvarum ITEM8795 was further selected and it was co- and sequentially inoculated, jointly with the S. cerevisiae starter, in a pilot scale wine production. The fermentation course and the quality of final product indicated that the co-inoculation was the better performing modality of inoculum. The above results were finally validated by performing an industrial scale vinification The mixed starter was able to successfully dominate the different stages of the fermentation process and the H. uvarum strain ITEM8795 contributed to increasing the wine organoleptic quality and to simultaneously reduce the volatile acidity. At the best of our knowledge, the present report is the first study regarding the utilization of a selected H. uvarum strain in multi-starter inoculation with S. cerevisiae for the industrial production of a wine. In addition, we demonstrated, at an industrial scale, the importance of non-Saccharomyces in

  11. The Oenological Potential of Hanseniaspora uvarum in Simultaneous and Sequential Co-fermentation with Saccharomyces cerevisiae for Industrial Wine Production.

    PubMed

    Tristezza, Mariana; Tufariello, Maria; Capozzi, Vittorio; Spano, Giuseppe; Mita, Giovanni; Grieco, Francesco

    2016-01-01

    In oenology, the utilization of mixed starter cultures composed by Saccharomyces and non-Saccharomyces yeasts is an approach of growing importance for winemakers in order to enhance sensory quality and complexity of the final product without compromising the general quality and safety of the oenological products. In fact, several non-Saccharomyces yeasts are already commercialized as oenological starter cultures to be used in combination with Saccharomyces cerevisiae, while several others are the subject of various studies to evaluate their application. Our aim, in this study was to assess, for the first time, the oenological potential of H. uvarum in mixed cultures (co-inoculation) and sequential inoculation with S. cerevisiae for industrial wine production. Three previously characterized H. uvarum strains were separately used as multi-starter together with an autochthonous S. cerevisiae starter culture in lab-scale micro-vinification trials. On the basis of microbial development, fermentation kinetics and secondary compounds formation, the strain H. uvarum ITEM8795 was further selected and it was co- and sequentially inoculated, jointly with the S. cerevisiae starter, in a pilot scale wine production. The fermentation course and the quality of final product indicated that the co-inoculation was the better performing modality of inoculum. The above results were finally validated by performing an industrial scale vinification The mixed starter was able to successfully dominate the different stages of the fermentation process and the H. uvarum strain ITEM8795 contributed to increasing the wine organoleptic quality and to simultaneously reduce the volatile acidity. At the best of our knowledge, the present report is the first study regarding the utilization of a selected H. uvarum strain in multi-starter inoculation with S. cerevisiae for the industrial production of a wine. In addition, we demonstrated, at an industrial scale, the importance of non-Saccharomyces in

  12. Ethanol production by Saccharomyces cerevisiae using lignocellulosic hydrolysate from Chrysanthemum waste degradation.

    PubMed

    Quevedo-Hidalgo, Balkys; Monsalve-Marín, Felipe; Narváez-Rincón, Paulo César; Pedroza-Rodríguez, Aura Marina; Velásquez-Lozano, Mario Enrique

    2013-03-01

    Ethanol production derived from Saccharomyces cerevisiae fermentation of a hydrolysate from floriculture waste degradation was studied. The hydrolysate was produced from Chrysanthemum (Dendranthema grandiflora) waste degradation by Pleurotus ostreatus and characterized to determine the presence of compounds that may inhibit fermentation. The products of hydrolysis confirmed by HPLC were cellobiose, glucose, xylose and mannose. The hydrolysate was fermented by S. cerevisiae, and concentrations of biomass, ethanol, and glucose were determined as a function of time. Results were compared to YGC modified medium (yeast extract, glucose and chloramphenicol) fermentation. Ethanol yield was 0.45 g g(-1), 88 % of the maximal theoretical value. Crysanthemum waste hydrolysate was suitable for ethanol production, containing glucose and mannose with adequate nutrients for S. cerevisiae fermentation and low fermentation inhibitor levels.

  13. Radioprotective effect of orally administered beta-d-glucan derived from Saccharomyces cerevisiae.

    PubMed

    Liu, Fang; Wang, Zhuanzi; Liu, Jia; Li, Wenjian

    2018-04-21

    The present study was to evaluate the in vivo radioprotective effect of oral administration of Saccharomyces cerevisiae-derived-beta-d-glucan (S. cerevisiae-BG) and to investigate the protective mechanism. The results demonstrated that oral pretreatment with 350 mg/kg S. cerevisiae-BG once daily for 14 consecutive days significantly increased the survival rate of mice from 6 Gy X-rays irradiation. At the 30th day after irradiation, cellularity and the percentage of hematopoietic stem/progenitor cells in bone marrow (BM) of surviving mice were increased by S. cerevisiae-BG. Further studies showed that S. cerevisiae-BG decreased BM cell DNA damage and improved BM cell cycle progress in irradiated mice. And the reactive oxygen species (ROS) levels in BM cells of irradiated mice were also decreased by S. cerevisiae-BG. These results indicated that oral S. cerevisiae-BG exhibited obviously radioprotective effect in mice and the protective effect may be attributed to the polysaccharide's hematopoiesis-modulating action and free radical scavenging property. S. cerevisiae-BG protects BM cells from radiation damage through scavenging BM cell ROS, mitigating BM cell DNA damage and improving cell cycle progress, and thus mitigated myelosuppression induced by irradiation and stimulated hematopoiesis, ultimately increased the survival of radiated mice. Copyright © 2018. Published by Elsevier B.V.

  14. Interactions between Lactobacillus kefiranofaciens and Saccharomyces cerevisiae in mixed culture for kefiran production.

    PubMed

    Cheirsilp, Benjamas; Shoji, Hirofumi; Shimizu, Hiroshi; Shioya, Suteaki

    2003-01-01

    Since a positive effect on the growth and kefiran production of Lactobacillus kefiranofaciens was observed in a mixed culture with Saccharomyces cerevisiae, the elucidation of the interactions between L. kefiranofaciens and S. cerevisiae may lead to higher productivity. Hence, the microbial interaction of each strain was investigated. Apart from the positive effect of a reduction in the amount of lactic acid by S. cerevisiae, a positive effect of S. cerevisiae on the growth and kefiran production of L. kefiranofaciens in a mixed culture was observed. Various experiments were carried out to study this effect. In this study, the observed increase in capsular kefiran in a mixed culture with inactivated S. cerevisiae correlated well to that in an anaerobic mixed culture. Differences in capsular kefiran production were observed for different initial S. cerevisiae concentrations under anaerobic conditions. From these fermentation results, it was concluded that the physical contact with S. cerevisiae mainly enhanced the capsular kefiran production of L. kefiranofaciens in a mixed culture. Therefore, in an anaerobic mixed culture, this direct contact resulted in higher capsular kefiran production than that in pure culture.

  15. Secretory Overexpression of Bacillus thermocatenulatus Lipase in Saccharomyces cerevisiae Using Combinatorial Library Strategy.

    PubMed

    Kajiwara, Shota; Yamada, Ryosuke; Ogino, Hiroyasu

    2018-04-10

    Simple and cost-effective lipase expression host microorganisms are highly desirable. A combinatorial library strategy is used to improve the secretory expression of lipase from Bacillus thermocatenulatus (BTL2) in the culture supernatant of Saccharomyces cerevisiae. A plasmid library including expression cassettes composed of sequences encoding one of each 15 promoters, 15 secretion signals, and 15 terminators derived from yeast species, S. cerevisiae, Pichia pastoris, and Hansenula polymorpha, is constructed. The S. cerevisiae transformant YPH499/D4, comprising H. polymorpha GAP promoter, S. cerevisiae SAG1 secretion signal, and P. pastoris AOX1 terminator, is selected by high-throughput screening. This transformant expresses BTL2 extra-cellularly with a 130-fold higher than the control strain, comprising S. cerevisiae PGK1 promoter, S. cerevisiae α-factor secretion signal, and S. cerevisiae PGK1 terminator, after cultivation for 72 h. This combinatorial library strategy holds promising potential for application in the optimization of the secretory expression of proteins in yeast. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Air-liquid biofilm formation is dependent on ammonium depletion in a Saccharomyces cerevisiae flor strain.

    PubMed

    Zara, Giacomo; Budroni, Marilena; Mannazzu, Ilaria; Zara, Severino

    2011-12-01

    Air-liquid biofilm formation appears to be an adaptive mechanism that promotes foraging of Saccharomyces cerevisiae flor strains in response to nutrient starvation. The FLO11 gene plays a central role in this phenotype as its expression allows yeast cells to rise to the liquid surface. Here, we investigated the role of ammonium depletion in air-liquid biofilm formation and FLO11 expression in a S. cerevisiae flor strain. The data obtained show that increasing ammonium concentrations from 0 to 450 m m reduce air-liquid biofilm in terms of biomass and velum formation and correlate with a reduction of FLO11 expression. Rapamycin inhibition of the TOR pathway and deletion of RAS2 gene significantly reduced biofilm formation and FLO11 expression. Taken together, these data suggest that ammonium depletion is a key factor in the induction of air-liquid biofilm formation and FLO11 expression in S. cerevisiae flor strains. Copyright © 2011 John Wiley & Sons, Ltd.

  17. Impact of glutathione metabolism on zinc homeostasis in Saccharomyces cerevisiae.

    PubMed

    Steiger, Matthias G; Patzschke, Anett; Holz, Caterina; Lang, Christine; Causon, Tim; Hann, Stephan; Mattanovich, Diethard; Sauer, Michael

    2017-06-01

    Zinc is a crucial mineral for all organisms as it is an essential cofactor for the proper function of a plethora of proteins and depletion of zinc causes oxidative stress. Glutathione is the major redox buffering agent in the cell and therefore important for mitigation of the adverse effects of oxidative stress. In mammalian cells, zinc deficiency is accompanied by a glutathione depletion. In the yeast Saccharomyces cerevisiae, the opposite effect is observed: under low zinc conditions, an elevated glutathione concentration is found. The main regulator to overcome zinc deficiency is Zap1p. However, we show that Zap1p is not involved in this glutathione accumulation phenotype. Furthermore, we found that in glutathione-accumulating strains also the metal ion-binding phytochelatin-2, which is an oligomer of glutathione, is accumulated. This increased phytochelatin concentration correlates with a lower free zinc level in the vacuole. These results suggest that phytochelatin is important for zinc buffering in S. cerevisiae and thus explains how zinc homeostasis is connected with glutathione metabolism. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Division of labour in the yeast: Saccharomyces cerevisiae.

    PubMed

    Wloch-Salamon, Dominika M; Fisher, Roberta M; Regenberg, Birgitte

    2017-10-01

    Division of labour between different specialized cell types is a central part of how we describe complexity in multicellular organisms. However, it is increasingly being recognized that division of labour also plays an important role in the lives of predominantly unicellular organisms. Saccharomyces cerevisiae displays several phenotypes that could be considered a division of labour, including quiescence, apoptosis and biofilm formation, but they have not been explicitly treated as such. We discuss each of these examples, using a definition of division of labour that involves phenotypic variation between cells within a population, cooperation between cells performing different tasks and maximization of the inclusive fitness of all cells involved. We then propose future research directions and possible experimental tests using S. cerevisiae as a model organism for understanding the genetic mechanisms and selective pressures that can lead to the evolution of the very first stages of a division of labour. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  19. Energy-dependent effects of resveratrol in Saccharomyces cerevisiae.

    PubMed

    Madrigal-Perez, Luis Alberto; Canizal-Garcia, Melina; González-Hernández, Juan Carlos; Reynoso-Camacho, Rosalia; Nava, Gerardo M; Ramos-Gomez, Minerva

    2016-06-01

    The metabolic effects induced by resveratrol have been associated mainly with the consumption of high-calorie diets; however, its effects with standard or low-calorie diets remain unclear. To better understand the interactions between resveratrol and cellular energy levels, we used Saccharomyces cerevisiae as a model. Herein it is shown that resveratrol: (a) decreased cell viability in an energy-dependent manner; (b) lessening of cell viability occurred specifically when cells were under cellular respiration; and (c) inhibition of oxygen consumption in state 4 occurred at low and standard energy levels, whereas at high energy levels oxygen consumption was promoted. These findings indicate that the effects of resveratrol are dependent on the cellular energy status and linked to metabolic respiration. Importantly, our study also revealed that S. cerevisiae is a suitable and useful model to elucidate the molecular targets of resveratrol under different nutritional statuses. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  20. Regulation of xylose metabolism in recombinant Saccharomyces cerevisiae

    PubMed Central

    Salusjärvi, Laura; Kankainen, Matti; Soliymani, Rabah; Pitkänen, Juha-Pekka; Penttilä, Merja; Ruohonen, Laura

    2008-01-01

    Background Considerable interest in the bioconversion of lignocellulosic biomass into ethanol has led to metabolic engineering of Saccharomyces cerevisiae for fermentation of xylose. In the present study, the transcriptome and proteome of recombinant, xylose-utilising S. cerevisiae grown in aerobic batch cultures on xylose were compared with those of glucose-grown cells both in glucose repressed and derepressed states. The aim was to study at the genome-wide level how signalling and carbon catabolite repression differ in cells grown on either glucose or xylose. The more detailed knowledge whether xylose is sensed as a fermentable carbon source, capable of catabolite repression like glucose, or is rather recognised as a non-fermentable carbon source is important for further engineering this yeast for more efficient anaerobic fermentation of xylose. Results Genes encoding respiratory proteins, proteins of the tricarboxylic acid and glyoxylate cycles, and gluconeogenesis were only partially repressed by xylose, similar to the genes encoding their transcriptional regulators HAP4, CAT8 and SIP1-2 and 4. Several genes that are repressed via the Snf1p/Mig1p-pathway during growth on glucose had higher expression in the cells grown on xylose than in the glucose repressed cells but lower than in the glucose derepressed cells. The observed expression profiles of the transcription repressor RGT1 and its target genes HXT2-3, encoding hexose transporters suggested that extracellular xylose was sensed by the glucose sensors Rgt2p and Snf3p. Proteome analyses revealed distinct patterns in phosphorylation of hexokinase 2, glucokinase and enolase isoenzymes in the xylose- and glucose-grown cells. Conclusion The results indicate that the metabolism of yeast growing on xylose corresponds neither to that of fully glucose repressed cells nor that of derepressed cells. This may be one of the major reasons for the suboptimal fermentation of xylose by recombinant S. cerevisiae strains

  1. Chromosome Duplication in Saccharomyces cerevisiae

    PubMed Central

    Bell, Stephen P.; Labib, Karim

    2016-01-01

    The accurate and complete replication of genomic DNA is essential for all life. In eukaryotic cells, the assembly of the multi-enzyme replisomes that perform replication is divided into stages that occur at distinct phases of the cell cycle. Replicative DNA helicases are loaded around origins of DNA replication exclusively during G1 phase. The loaded helicases are then activated during S phase and associate with the replicative DNA polymerases and other accessory proteins. The function of the resulting replisomes is monitored by checkpoint proteins that protect arrested replisomes and inhibit new initiation when replication is inhibited. The replisome also coordinates nucleosome disassembly, assembly, and the establishment of sister chromatid cohesion. Finally, when two replisomes converge they are disassembled. Studies in Saccharomyces cerevisiae have led the way in our understanding of these processes. Here, we review our increasingly molecular understanding of these events and their regulation. PMID:27384026

  2. Mitochondrial introgression suggests extensive ancestral hybridization events among Saccharomyces species.

    PubMed

    Peris, David; Arias, Armando; Orlić, Sandi; Belloch, Carmela; Pérez-Través, Laura; Querol, Amparo; Barrio, Eladio

    2017-03-01

    Horizontal gene transfer (HGT) in eukaryotic plastids and mitochondrial genomes is common, and plays an important role in organism evolution. In yeasts, recent mitochondrial HGT has been suggested between S. cerevisiae and S. paradoxus. However, few strains have been explored given the lack of accurate mitochondrial genome annotations. Mitochondrial genome sequences are important to understand how frequent these introgressions occur, and their role in cytonuclear incompatibilities and fitness. Indeed, most of the Bateson-Dobzhansky-Muller genetic incompatibilities described in yeasts are driven by cytonuclear incompatibilities. We herein explored the mitochondrial inheritance of several worldwide distributed wild Saccharomyces species and their hybrids isolated from different sources and geographic origins. We demonstrated the existence of several recombination points in mitochondrial region COX2-ORF1, likely mediated by either the activity of the protein encoded by the ORF1 (F-SceIII) gene, a free-standing homing endonuclease, or mostly facilitated by A+T tandem repeats and regions of integration of GC clusters. These introgressions were shown to occur among strains of the same species and among strains of different species, which suggests a complex model of Saccharomyces evolution that involves several ancestral hybridization events in wild environments. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Saccharomyces cerevisiae × Saccharomyces uvarum hybrids generated under different conditions share similar winemaking features.

    PubMed

    Origone, Andrea Cecilia; Rodríguez, María Eugenia; Oteiza, Juan Martín; Querol, Amparo; Lopes, Christian Ariel

    2018-01-01

    Interspecific hybrids among species in the Saccharomyces genus are frequently detected in anthropic habitats and can also be obtained easily in the laboratory. This occurs because the most important genetic barriers among Saccharomyces species are post-zygotic. Depending on several factors, including the involved strains, the hybridization mechanism and stabilization conditions, hybrids that bear differential genomic constitutions, and hence phenotypic variability, can be obtained. In the present study, Saccharomyces cerevisiae × Saccharomyces uvarum hybrids were constructed using genetically and physiologically different S. uvarum parents at distinct temperatures (13 and 20°C). The effect of those variables on the main oenological features of the wines obtained with these hybrids was evaluated. Hybrids were successfully obtained in all cases. However, genetic stabilization based on successive fermentations in white wine at 13°C was significantly longer than that at 20°C. Our results demonstrated that, irrespective of the S. uvarum parent and temperature used for hybrid generation and stabilization, similar physicochemical and aromatic features were found in wines. The hybrids generated herein were characterized by low ethanol production, high glycerol synthesis and the capacity to grow at low temperature and to produce malic acid with particular aroma profiles. These features make these hybrids useful for the new winemaking industry within the climate change era frame. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  4. Transcriptome-Based Characterization of Interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaricus in Lactose-Grown Chemostat Cocultures

    PubMed Central

    Mendes, Filipa; Sieuwerts, Sander; de Hulster, Erik; Almering, Marinka J. H.; Luttik, Marijke A. H.; Pronk, Jack T.; Smid, Eddy J.; Bron, Peter A.

    2013-01-01

    Mixed populations of Saccharomyces cerevisiae yeasts and lactic acid bacteria occur in many dairy, food, and beverage fermentations, but knowledge about their interactions is incomplete. In the present study, interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaricus, two microorganisms that co-occur in kefir fermentations, were studied during anaerobic growth on lactose. By combining physiological and transcriptome analysis of the two strains in the cocultures, five mechanisms of interaction were identified. (i) Lb. delbrueckii subsp. bulgaricus hydrolyzes lactose, which cannot be metabolized by S. cerevisiae, to galactose and glucose. Subsequently, galactose, which cannot be metabolized by Lb. delbrueckii subsp. bulgaricus, is excreted and provides a carbon source for yeast. (ii) In pure cultures, Lb. delbrueckii subsp. bulgaricus grows only in the presence of increased CO2 concentrations. In anaerobic mixed cultures, the yeast provides this CO2 via alcoholic fermentation. (iii) Analysis of amino acid consumption from the defined medium indicated that S. cerevisiae supplied alanine to the bacterium. (iv) A mild but significant low-iron response in the yeast transcriptome, identified by DNA microarray analysis, was consistent with the chelation of iron by the lactate produced by Lb. delbrueckii subsp. bulgaricus. (v) Transcriptome analysis of Lb. delbrueckii subsp. bulgaricus in mixed cultures showed an overrepresentation of transcripts involved in lipid metabolism, suggesting either a competition of the two microorganisms for fatty acids or a response to the ethanol produced by S. cerevisiae. This study demonstrates that chemostat-based transcriptome analysis is a powerful tool to investigate microbial interactions in mixed populations. PMID:23872557

  5. Transcriptome-based characterization of interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaricus in lactose-grown chemostat cocultures.

    PubMed

    Mendes, Filipa; Sieuwerts, Sander; de Hulster, Erik; Almering, Marinka J H; Luttik, Marijke A H; Pronk, Jack T; Smid, Eddy J; Bron, Peter A; Daran-Lapujade, Pascale

    2013-10-01

    Mixed populations of Saccharomyces cerevisiae yeasts and lactic acid bacteria occur in many dairy, food, and beverage fermentations, but knowledge about their interactions is incomplete. In the present study, interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaricus, two microorganisms that co-occur in kefir fermentations, were studied during anaerobic growth on lactose. By combining physiological and transcriptome analysis of the two strains in the cocultures, five mechanisms of interaction were identified. (i) Lb. delbrueckii subsp. bulgaricus hydrolyzes lactose, which cannot be metabolized by S. cerevisiae, to galactose and glucose. Subsequently, galactose, which cannot be metabolized by Lb. delbrueckii subsp. bulgaricus, is excreted and provides a carbon source for yeast. (ii) In pure cultures, Lb. delbrueckii subsp. bulgaricus grows only in the presence of increased CO2 concentrations. In anaerobic mixed cultures, the yeast provides this CO2 via alcoholic fermentation. (iii) Analysis of amino acid consumption from the defined medium indicated that S. cerevisiae supplied alanine to the bacterium. (iv) A mild but significant low-iron response in the yeast transcriptome, identified by DNA microarray analysis, was consistent with the chelation of iron by the lactate produced by Lb. delbrueckii subsp. bulgaricus. (v) Transcriptome analysis of Lb. delbrueckii subsp. bulgaricus in mixed cultures showed an overrepresentation of transcripts involved in lipid metabolism, suggesting either a competition of the two microorganisms for fatty acids or a response to the ethanol produced by S. cerevisiae. This study demonstrates that chemostat-based transcriptome analysis is a powerful tool to investigate microbial interactions in mixed populations.

  6. Replication profile of Saccharomyces cerevisiae chromosome VI.

    PubMed

    Friedman, K L; Brewer, B J; Fangman, W L

    1997-11-01

    An understanding of the replication programme at the genome level will require the identification and characterization of origins of replication through large, contiguous regions of DNA. As a step toward this goal, origin efficiencies and replication times were determined for 10 ARSs spanning most of the 270 kilobase (kb) chromosome VI of Saccharomyces cerevisiae. Chromosome VI shows a wide variation in the percentage of cell cycles in which different replication origins are utilized. Most of the origins are activated in only a fraction of cells, suggesting that the pattern of origin usage on chromosome VI varies greatly within the cell population. The replication times of fragments containing chromosome VI origins show a temporal pattern that has been recognized on other chromosomes--the telomeres replicate late in S phase, while the central region of the chromosome replicates early. As demonstrated here for chromosome VI, analysis of the direction of replication fork movement along a chromosome and determination of replication time by measuring a period of hemimethylation may provide an efficient means of surveying origin activity over large regions of the genome.

  7. Deletion of JJJ1 improves acetic acid tolerance and bioethanol fermentation performance of Saccharomyces cerevisiae strains.

    PubMed

    Wu, Xuechang; Zhang, Lijie; Jin, Xinna; Fang, Yahong; Zhang, Ke; Qi, Lei; Zheng, Daoqiong

    2016-07-01

    To improve tolerance to acetic acid that is present in lignocellulosic hydrolysates and affects bioethanol production by Saccharomyces cerevisiae. Saccharomyces cerevisiae strains with improved tolerance to acetic acid were obtained through deletion of the JJJ1 gene. The lag phase of the JJJ1 deletion mutant BYΔJJJ1 was ~16 h shorter than that of the parent strain, BY4741, when the fermentation medium contained 4.5 g acetic acid/l. Additionally, the specific ethanol production rate of BYΔJJJ1 was increased (0.057 g/g h) compared to that of the parent strain (0.051 g/g h). Comparative transcription and physiological analyses revealed higher long chain fatty acid, trehalose, and catalase contents might be critical factors responsible for the acetic acid resistance of JJJ1 knockout strains. JJJ1 deletion improves acetic acid tolerance and ethanol fermentation performance of S. cerevisiae.

  8. Functional analysis of Paracoccidioides brasiliensis 14-3-3 adhesin expressed in Saccharomyces cerevisiae.

    PubMed

    Assato, Patricia Akemi; da Silva, Julhiany de Fátima; de Oliveira, Haroldo Cesar; Marcos, Caroline Maria; Rossi, Danuza; Valentini, Sandro Roberto; Mendes-Giannini, Maria José Soares; Zanelli, Cleslei Fernando; Fusco-Almeida, Ana Marisa

    2015-11-04

    14-3-3 proteins comprise a family of eukaryotic multifunctional proteins involved in several cellular processes. The Pb14-3-3 of Paracoccidioides brasiliensis seems to play an important role in the Paracoccidioides-host interaction. Paracoccidioides brasiliensis is an etiological agent of paracoccidioidomycosis, which is a systemic mycosis that is endemic in Latin America. In the initial steps of the infection, Paracoccidioides spp. synthetizes adhesins that allow it to adhere and invade host cells. Therefore, the aim of this work was to perform a functional analysis of Pb14-3-3 using Saccharomyces cerevisiae as a model. The functional analysis of Pb14-3-3 was performed in S. cerevisiae, and it was found that Pb14-3-3 partially complemented S. cerevisiae proteins Bmh1p and Bmh2p, which are recognized as two yeast 14-3-3 homologues. When we evaluated the adhesion profile of S. cerevisiae transformants, Pb14-3-3 acted as an adhesin in S. cerevisiae; however, Bmh1p did not show this function. The influence of Pb14-3-3 in S. cerevisiae ergosterol pathway was also evaluated and our results showed that Pb14-3-3 up-regulates genes involved in ergosterol biosynthesis. Our data showed that Pb14-3-3 was able to partially complement Bmh1p and Bmh2p proteins in S. cerevisiae; however, we suggest that Pb14-3-3 has a differential role as an adhesin. In addition, Pb-14-3-3 may be involved in Paracoccidioides spp. ergosterol biosynthesis which makes it an interest as a therapeutic target.

  9. Mixing of vineyard and oak-tree ecotypes of Saccharomyces cerevisiae in North American vineyards

    PubMed Central

    Hyma, Katie E.; Fay, Justin C.

    2012-01-01

    Humans have had a significant impact on the distribution and abundance of Saccharomyces cerevisiae through its widespread use in beer, bread and wine production. Yet, similar to other Saccharomyces species, S. cerevisiae has also been isolated from habitats unrelated to fermentations. Strains of S. cerevisiae isolated from grapes, wine must and vineyards worldwide are genetically differentiated from strains isolated from oak-tree bark, exudate and associated soil in North America. However, the causes and consequences of this differentiation have not yet been resolved. Historical differentiation of these two groups may have been influenced by geographic, ecological or human-associated barriers to gene flow. Here, we make use of the relatively recent establishment of vineyards across North America to identify and characterize any active barriers to gene flow between these two groups. We examined S. cerevisiae strains isolated from grapes and oak-trees within three North American vineyards and compared them to those isolated from oak-trees outside of vineyards. Within vineyards we found evidence of migration between grapes and oak-trees and potential gene flow between the divergent oak-tree and vineyard groups. Yet, we found no vineyard genotypes on oak-trees outside of vineyards. In contrast, S. paradoxus isolated from the same sources showed population structure characterized by isolation by distance. The apparent absence of ecological or genetic barriers between sympatric vineyard and oak-tree populations of S. cerevisiae implies that vineyards play an important role in the mixing between these two groups. PMID:23286354

  10. Sucrose fermentation by Saccharomyces cerevisiae lacking hexose transport.

    PubMed

    Batista, Anderson S; Miletti, Luiz C; Stambuk, Boris U

    2004-01-01

    Sucrose is the major carbon source used by Saccharomyces cerevisiae during production of baker's yeast, fuel ethanol and several distilled beverages. It is generally accepted that sucrose fermentation proceeds through extracellular hydrolysis of the sugar, mediated by the periplasmic invertase, producing glucose and fructose that are transported into the cells and metabolized. In the present work we analyzed the contribution to sucrose fermentation of a poorly characterized pathway of sucrose utilization by S. cerevisiae cells, the active transport of the sugar through the plasma membrane and its intracellular hydrolysis. A yeast strain that lacks the major hexose transporters (hxt1-hxt7 and gal2) is incapable of growing on or fermenting glucose or fructose. Our results show that this hxt-null strain is still able to ferment sucrose due to direct uptake of the sugar into the cells. Deletion of the AGT1 gene, which encodes a high-affinity sucrose-H(+) symporter, rendered cells incapable of sucrose fermentation. Since sucrose is not an inducer of the permease, expression of the AGT1 must be constitutive in order to allow growth of the hxt-null strain on sucrose. The molecular characterization of active sucrose transport and fermentation by S. cerevisiae cells opens new opportunities to optimize yeasts for sugarcane-based industrial processes.

  11. Optimization of air-blast drying process for manufacturing Saccharomyces cerevisiae and non-Saccharomyces yeast as industrial wine starters.

    PubMed

    Lee, Sae-Byuk; Choi, Won-Seok; Jo, Hyun-Jung; Yeo, Soo-Hwan; Park, Heui-Dong

    2016-12-01

    Wine yeast (Saccharomyces cerevisiae D8) and non-Saccharomyces wine yeasts (Hanseniaspora uvarum S6 and Issatchenkia orientalis KMBL5774) were studied using air-blast drying instead of the conventional drying methods (such as freeze and spray drying). Skim milk-a widely used protective agent-was used and in all strains, the highest viabilities following air-blast drying were obtained using 10% skim milk. Four excipients (wheat flour, nuruk, artichoke powder, and lactomil) were evaluated as protective agents for yeast strains during air-blast drying. Our results showed that 7 g lactomil was the best excipient in terms of drying time, powder form, and the survival rate of the yeast in the final product. Finally, 7 types of sugars were investigated to improve the survival rate of air-blast dried yeast cells: 10% trehalose, 10% sucrose, and 10% glucose had the highest survival rate of 97.54, 92.59, and 79.49% for S. cerevisiae D8, H. uvarum S6, and I. orientalis KMBL5774, respectively. After 3 months of storage, S. cerevisiae D8 and H. uvarum S6 demonstrated good survival rates (making them suitable for use as starters), whereas the survival rate of I. orientalis KMBL5774 decreased considerably compared to the other strains. Air-blast dried S. cerevisiae D8 and H. uvarum S6 showed metabolic activities similar to those of non-dried yeast cells, regardless of the storage period. Air-blast dried I. orientalis KMBL5774 showed a noticeable decrease in its ability to decompose malic acid after 3 months of storage at 4 °C.

  12. Genome Sequence of Saccharomyces cerevisiae Double-Stranded RNA Virus L-A-28.

    PubMed

    Konovalovas, Aleksandras; Serviené, Elena; Serva, Saulius

    2016-06-16

    We cloned and sequenced the complete genome of the L-A-28 virus from the Saccharomyces cerevisiae K28 killer strain. This sequence completes the set of currently identified L-A helper viruses required for expression of double-stranded RNA-originated killer phenotypes in baking yeast. Copyright © 2016 Konovalovas et al.

  13. Proton Gradient-Driven Nickel Uptake by Vacuolar Membrane Vesicles of Saccharomyces cerevisiae

    PubMed Central

    Nishimura, Ken; Igarashi, Kazuei; Kakinuma, Yoshimi

    1998-01-01

    A vacuolar H+-ATPase-negative mutant of Saccharomyces cerevisiae was highly sensitive to nickel ion. Accumulation of nickel ion in the cells of this mutant of less than 60% of the value for the parent strain arrested growth, suggesting a role for this ATPase in sequestering nickel ion into vacuoles. An artificially imposed pH gradient (interior acid) induced transient nickel ion uptake by vacuolar membrane vesicles, which was inhibited by collapse of the pH difference but not of the membrane potential. Nickel ion transport into vacuoles in a pH gradient-dependent manner is thus important for its detoxification in yeast. PMID:9537401

  14. Genetic Manipulation of Palmitoylethanolamide Production and Inactivation in Saccharomyces cerevisiae

    PubMed Central

    Muccioli, Giulio G.; Sia, Angela; Muchowski, Paul J.; Stella, Nephi

    2009-01-01

    Background Lipids can act as signaling molecules, activating intracellular and membrane-associated receptors to regulate physiological functions. To understand how a newly discovered signaling lipid functions, it is necessary to identify and characterize the enzymes involved in their production and inactivation. The signaling lipid N-palmitoylethanolamine (PEA) is known to activate intracellular and membrane-associated receptors and regulate physiological functions, but little is known about the enzymes involved in its production and inactivation. Principal Findings Here we show that Saccharomyces cerevisiae produce and inactivate PEA, suggesting that genetic manipulations of this lower eukaryote may be used to identify the enzymes involved in PEA metabolism. Accordingly, using single gene deletion mutants, we identified yeast genes that control PEA metabolism, including SPO14 (a yeast homologue of the mammalian phospholipase D) that controls PEA production and YJU3 (a yeast homologue of the mammalian monoacylglycerol lipase) that controls PEA inactivation. We also found that PEA metabolism is affected by heterologous expression of two mammalian proteins involved in neurodegenerative diseases, namely huntingtin and α-synuclein. Significance Together these findings show that forward and reverse genetics in S. cerevisiae can be used to identify proteins involved in PEA production and inactivation, and suggest that mutated proteins causing neurodegenerative diseases might affect the metabolism of this important signaling lipid. PMID:19529773

  15. Saccharomyces cerevisiae show low levels of traversal across human endothelial barrier in vitro.

    PubMed

    Pérez-Torrado, Roberto; Querol, Amparo

    2017-01-01

    Background :   Saccharomyces cerevisiae is generally considered safe, and is involved in the production of many types of foods and dietary supplements. However, some isolates, which are genetically related to strains used in brewing and baking, have shown virulent traits, being able to produce infections in humans, mainly in immunodeficient patients. This can lead to systemic infections in humans. Methods : In this work, we studied S. cerevisiae isolates in an in vitro human endothelial barrier model, comparing their behaviour with that of several strains of the related pathogens Candida glabrata and Candida albicans . Results : The results showed that this food related yeast is able to cross the endothelial barrier in vitro . However, in contrast to C. glabrata and C. albicans , S. cerevisiae showed very low levels of traversal. Conclusions : We conclude that using an in vitro human endothelial barrier model with S. cerevisiae can be useful to evaluate the safety of S. cerevisiae strains isolated from foods.

  16. Overexpression of acetyl-CoA synthetase in Saccharomyces cerevisiae increases acetic acid tolerance

    PubMed Central

    Ding, Jun; Holzwarth, Garrett; Penner, Michael H.; Patton-Vogt, Jana; Bakalinsky, Alan T.

    2015-01-01

    Acetic acid-mediated inhibition of the fermentation of lignocellulose-derived sugars impedes development of plant biomass as a source of renewable ethanol. In order to overcome this inhibition, the capacity of Saccharomyces cerevisiae to synthesize acetyl-CoA from acetic acid was increased by overexpressing ACS2 encoding acetyl-coenzyme A synthetase. Overexpression of ACS2 resulted in higher resistance to acetic acid as measured by an increased growth rate and shorter lag phase relative to a wild-type control strain, suggesting that Acs2-mediated consumption of acetic acid during fermentation contributes to acetic acid detoxification. PMID:25673654

  17. Molecular Basis for Strain Variation in the Saccharomyces cerevisiae Adhesin Flo11p

    PubMed Central

    Li, Li; Lipke, Peter N.; Dranginis, Anne M.

    2016-01-01

    ABSTRACT FLO11 encodes a yeast cell wall flocculin that mediates a variety of adhesive phenotypes in Saccharomyces cerevisiae. Flo11p is implicated in many developmental processes, including flocculation, formation of pseudohyphae, agar invasion, and formation of microbial mats and biofilms. However, Flo11p mediates different processes in different yeast strains. To investigate the mechanisms by which FLO11 determines these differences in colony morphology, flocculation, and invasion, we studied gene structure, function, and expression levels. Nonflocculent Saccharomyces cerevisiae Σ1278b cells exhibited significantly higher FLO11 mRNA expression, especially in the stationary phase, than highly flocculent S. cerevisiae var. diastaticus. The two strains varied in cell surface hydrophobicity, and Flo11p contributed significantly to surface hydrophobicity in S. cerevisiae var. diastaticus but not in strain Σ1278b. Sequencing of the FLO11 gene in S. cerevisiae var. diastaticus revealed strain-specific differences, including a 15-amino-acid insertion in the adhesion domain. Flo11p adhesion domains from strain Σ1278b and S. cerevisiae var. diastaticus were expressed and used to coat magnetic beads. The adhesion domain from each strain bound preferentially to homologous cells, and the preferences were independent of the cells in which the adhesion domains were produced. These results are consistent with the idea that strain-specific variations in the amino acid sequences in the adhesion domains cause different Flo11p flocculation activities. The results also imply that strain-specific differences in expression levels, posttranslational modifications, and allelic differences outside the adhesion domains have little effect on flocculation. IMPORTANCE As a nonmotile organism, Saccharomyces cerevisiae employs the cell surface flocculin Flo11/Muc1 as an important means of adapting to environmental change. However, there is a great deal of strain variation in the

  18. Role of hexose transport in control of glycolytic flux in Saccharomyces cerevisiae.

    PubMed

    Elbing, Karin; Larsson, Christer; Bill, Roslyn M; Albers, Eva; Snoep, Jacky L; Boles, Eckhard; Hohmann, Stefan; Gustafsson, Lena

    2004-09-01

    The yeast Saccharomyces cerevisiae predominantly ferments glucose to ethanol at high external glucose concentrations, irrespective of the presence of oxygen. In contrast, at low external glucose concentrations and in the presence of oxygen, as in a glucose-limited chemostat, no ethanol is produced. The importance of the external glucose concentration suggests a central role for the affinity and maximal transport rates of yeast's glucose transporters in the control of ethanol production. Here we present a series of strains producing functional chimeras between the hexose transporters Hxt1 and Hxt7, each of which has distinct glucose transport characteristics. The strains display a range of decreasing glycolytic rates resulting in a proportional decrease in ethanol production. Using these strains, we show for the first time that at high glucose levels, the glucose uptake capacity of wild-type S. cerevisiae does not control glycolytic flux during exponential batch growth. In contrast, our chimeric Hxt transporters control the rate of glycolysis to a high degree. Strains whose glucose uptake is mediated by these chimeric transporters will undoubtedly provide a powerful tool with which to examine in detail the mechanism underlying the switch between fermentation and respiration in S. cerevisiae and will provide new tools for the control of industrial fermentations.

  19. Role of Hexose Transport in Control of Glycolytic Flux in Saccharomyces cerevisiae

    PubMed Central

    Elbing, Karin; Larsson, Christer; Bill, Roslyn M.; Albers, Eva; Snoep, Jacky L.; Boles, Eckhard; Hohmann, Stefan; Gustafsson, Lena

    2004-01-01

    The yeast Saccharomyces cerevisiae predominantly ferments glucose to ethanol at high external glucose concentrations, irrespective of the presence of oxygen. In contrast, at low external glucose concentrations and in the presence of oxygen, as in a glucose-limited chemostat, no ethanol is produced. The importance of the external glucose concentration suggests a central role for the affinity and maximal transport rates of yeast's glucose transporters in the control of ethanol production. Here we present a series of strains producing functional chimeras between the hexose transporters Hxt1 and Hxt7, each of which has distinct glucose transport characteristics. The strains display a range of decreasing glycolytic rates resulting in a proportional decrease in ethanol production. Using these strains, we show for the first time that at high glucose levels, the glucose uptake capacity of wild-type S. cerevisiae does not control glycolytic flux during exponential batch growth. In contrast, our chimeric Hxt transporters control the rate of glycolysis to a high degree. Strains whose glucose uptake is mediated by these chimeric transporters will undoubtedly provide a powerful tool with which to examine in detail the mechanism underlying the switch between fermentation and respiration in S. cerevisiae and will provide new tools for the control of industrial fermentations. PMID:15345416

  20. Enhancing Fatty Acid Production of Saccharomyces cerevisiae as an Animal Feed Supplement.

    PubMed

    You, Seung Kyou; Joo, Young-Chul; Kang, Dae Hee; Shin, Sang Kyu; Hyeon, Jeong Eun; Woo, Han Min; Um, Youngsoon; Park, Chulhwan; Han, Sung Ok

    2017-12-20

    Saccharomyces cerevisiae is used for edible purposes, such as human food or as an animal feed supplement. Fatty acids are also beneficial as feed supplements, but S. cerevisiae produces small amounts of fatty acids. In this study, we enhanced fatty acid production of S. cerevisiae by overexpressing acetyl-CoA carboxylase, thioesterase, and malic enzyme associated with fatty acid metabolism. The enhanced strain pAMT showed 2.4-fold higher fatty acids than the wild-type strain. To further increase the fatty acids, various nitrogen sources were analyzed and calcium nitrate was selected as an optimal nitrogen source for fatty acid production. By concentration optimization, 672 mg/L of fatty acids was produced, which was 4.7-fold higher than wild-type strain. These results complement the low level fatty acid production and make it possible to obtain the benefits of fatty acids as an animal feed supplement while, simultaneously, maintaining the advantages of S. cerevisiae.

  1. Determination of biological activity from fluorescence-lifetime measurements in Saccharomyces cerevisiae

    NASA Astrophysics Data System (ADS)

    Rudek, F.; Baselt, T.; Lempe, B.; Taudt, C.; Hartmann, P.

    2015-03-01

    The importance of fluorescence lifetime measurement as an optical analysis tool is growing. Many applications already exist in order to determine the fluorescence lifetime, but the majority of these require the addition of fluorescence-active substances to enable measurements. Every usage of such foreign materials has an associated risk. This paper investigates the use of auto-fluorescing substances in Saccharomyces cerevisiae (Baker's yeast) as a risk free alternative to fluorescence-active substance enabled measurements. The experimental setup uses a nitrogen laser with a pulse length of 350 ps and a wavelength of 337 nm. The excited sample emits light due to fluorescence of NADH/NADPH and collagen. A fast photodiode collects the light at the output of an appropriate high-pass edge-filter at 400 nm. Fluorescence lifetimes can be determined from the decay of the measurement signals, which in turn characterizes the individual materials and their surrounding environment. Information about the quantity of the fluorescence active substances can also be measured based on the received signal intensity. The correlation between the fluorescence lifetime and the metabolic state of Saccharomyces cerevisiae was investigated and is presented here.

  2. Modulation of the acute phase response in feedlot steers supplemented with Saccharomyces cerevisiae

    USDA-ARS?s Scientific Manuscript database

    This study was designed to determine the effect of supplementing feedlot steers with Saccharomyces cerevisiae CNCM I-1079 (SC) on the acute phase response to a lipopolysaccharide (LPS) challenge. Steers (n = 18; 266 ± 4 kilograms body weight) were separated into three treatment groups (n = 6/treatm...

  3. Cell Surface Display of Four Types of Solanum nigrum Metallothionein on Saccharomyces cerevisiae for Biosorption of Cadmium.

    PubMed

    Wei, Qinguo; Zhang, Honghai; Guo, Dongge; Ma, Shisheng

    2016-05-28

    We displayed four types of Solanum nigrum metallothionein (SMT) for the first time on the surface of Saccharomyces cerevisiae using an α-agglutinin-based display system. The SMT genes were amplified by RT-PCR. The plasmid pYES2 was used to construct the expression vector. Transformed yeast strains were confirmed by PCR amplification and custom sequencing. Surface-expressed metallothioneins were indirectly indicated by the enhanced cadmium sorption capacity. Flame atomic absorption spectrophotometry was used to examine the concentration of Cd(2+) in this study. The transformed yeast strains showed much higher resistance ability to Cd(2+) compared with the control. Strikingly, their Cd(2+) accumulation was almost twice as much as that of the wild-type yeast cells. Furthermore, surface-engineered yeast strains could effectively adsorb ultra-trace cadmium and accumulate Cd(2+) under a wide range of pH levels, from 3 to 7, without disturbing the Cu(2+) and Hg(2+). Four types of surfaceengineered Saccharomyces cerevisiae strains were constructed and they could be used to purify Cd(2+)-contaminated water and adsorb ultra-trace cadmium effectively. The surface-engineered Saccharomyces cerevisiae strains would be useful tools for the bioremediation and biosorption of environmental cadmium contaminants.

  4. Human acylphosphatase cannot replace phosphoglycerate kinase in Saccharomyces cerevisiae.

    PubMed

    Van Hoek, P; Modesti, A; Ramponi, G; Kötter, P; van Dijken, J P; Pron, J T

    2001-10-01

    Human acylphosphatase (h-AP, EC 3.6.1.7) has been reported to catalyse the hydrolysis of the 1-phosphate group of 1,3-diphosphoglycerate. In vivo operation of this reaction in the yeast Saccharomyces cerevisiae would bypass phosphoglycerate kinase and thus reduce the ATP yield from glycolysis. To investigate whether h-AP can indeed replace the S. cerevisiae phosphoglycerate kinase, a multi-copy plasmid carrying the h-AP gene under control of the yeast TDH3 promoter was introduced into a pgk1 delta mutant of S. cerevisiae. A strain carrying the expression vector without the h-AP cassette was used as a reference. For both strains, steady-state carbon- and energy-limited chemostat cultures were obtained at a dilution rate of 0.10 h(-1) on a medium containing a mixture of glucose and ethanol (15% and 85% on a carbon basis, respectively). Although the h-AP strain exhibited a high acylphosphatase activity in cell extracts, switching to glucose as sole carbon and energy source resulted in a complete arrest of glucose consumption and growth. The lack of a functional glycolytic pathway was further evident from the absence of ethanol formation in the presence of excess glucose in the culture. As h-AP cannot replace yeast phosphoglycerate kinase in vivo, the enzyme is not a useful tool to modify the ATP yield of glycolysis in S. cerevisiae.

  5. Production and Purification of the Native Saccharomyces cerevisiae Hsp12 in Escherichia coli.

    PubMed

    Léger, Antoine; Hocquellet, Agnès; Dieryck, Wilfrid; Moine, Virginie; Marchal, Axel; Marullo, Philippe; Josseaume, Annabelle; Cabanne, Charlotte

    2017-09-20

    Hsp12 is a small heat shock protein produced in many organisms, including the yeast Saccharomyces cerevisiae. It has been described as an indicator of yeast stress rate and has also been linked to the sweetness sensation of wine. To obtain a sufficient amount of protein, we produced and purified Hsp12 without tag in Escherichia coli. A simple fast two-step process was developed using a microplate approach and a design of experiments. A capture step on an anion-exchange salt-tolerant resin was followed by size exclusion chromatography for polishing, leading to a purity of 97%. Thereafter, specific anti-Hsp12 antibodies were obtained by rabbit immunization. An ELISA was developed to quantify Hsp12 in various strains of Saccharomyces cerevisiae. The antibodies showed high specificity and allowed the quantitation of Hsp12 in the yeast. The quantities of Hsp12 measured in the strains differed in direct proportion to the level of expression found in previous studies.

  6. Immunoproteomic profiling of Saccharomyces cerevisiae systemic infection in a murine model.

    PubMed

    Hernández-Haro, Carolina; Llopis, Silvia; Molina, María; Monteoliva, Lucía; Gil, Concha

    2015-01-01

    Saccharomyces cerevisiae is considered a safe microorganism widely used as a dietary supplement. However, in the latest decades several cases of S. cerevisiae infections have been reported. Recent studies in a murine model of systemic infection have also revealed the virulence of some S. cerevisiae dietary strains. Here we use an immunoproteomic approach based on protein separation by 2D-PAGE followed by Western-blotting to compare the serological response against a virulent dietary and a non-virulent laboratory strains leading to the identification of highly different patterns of antigenic proteins. Thirty-six proteins that elicit a serological response in mice have been identified. Most of them are involved in stress responses and metabolic pathways. Their selectivity as putative biomarkers for S. cerevisiae infections was assessed by testing sera from S. cerevisiae-infected mice against Candida albicans and C. glabrata proteins. Some chaperones and metabolic proteins showed cross-reactivity. We also compare the S. cerevisiae immunodetected proteins with previously described C. albicans antigens. The results point to the stress-related proteins Ahp1, Yhb1 and Oye2, as well as the glutamine synthetase Gln1 and the oxysosterol binding protein Kes1 as putative candidates for being evaluated as biomarkers for diagnostic assays of S. cerevisiae infections. S. cerevisiae can cause opportunistic infections, and therefore, a precise diagnosis of fungal infections is necessary. This immunoproteomic analysis of sera from a model murine infection with a virulent dietary S. cerevisiae strain has been shown to be a source of candidate proteins for being evaluated as biomarkers to develop assays for diagnosis of S. cerevisiae infections. To our knowledge, this is the first study devoted to the identification of S. cerevisiae immunogenic proteins and the results allowed the proposal of five antigens to be further investigated. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Monoterpenoid biosynthesis in Saccharomyces cerevisiae.

    PubMed

    Oswald, Marilyne; Fischer, Marc; Dirninger, Nicole; Karst, Francis

    2007-05-01

    Plant monoterpenoids belong to a large family of plant secondary metabolites with valuable applications in cosmetics and medicine. Their usual low levels and difficult purification justify the need for alternative fermentative processes for large-scale production. Geranyl diphosphate is the universal precursor of monoterpenoids. In yeast it occurs exclusively as an intermediate of farnesyl diphosphate synthesis. In the present study we investigated the potential use of Saccharomyces cerevisiae as an alternative engineering tool. The expression of geraniol synthase of Ocimum basilicum in yeast allowed a strong and specific excretion of geraniol to the growth medium, in contrast to mutants defective in farnesyl diphosphate synthase which excreted geraniol and linalool in similar amounts. A further increase of geraniol synthesis was obtained using yeast mutants defective in farnesyl diphosphate synthase. We also showed that geraniol synthase expression affects the general ergosterol pathway, but in a manner dependent on the genetic background of the strain.

  8. Phenotypic Landscape of Saccharomyces cerevisiae during Wine Fermentation: Evidence for Origin-Dependent Metabolic Traits

    PubMed Central

    Camarasa, Carole; Sanchez, Isabelle; Brial, Pascale; Bigey, Frédéric; Dequin, Sylvie

    2011-01-01

    The species Saccharomyces cerevisiae includes natural strains, clinical isolates, and a large number of strains used in human activities. The aim of this work was to investigate how the adaptation to a broad range of ecological niches may have selectively shaped the yeast metabolic network to generate specific phenotypes. Using 72 S. cerevisiae strains collected from various sources, we provide, for the first time, a population-scale picture of the fermentative metabolic traits found in the S. cerevisiae species under wine making conditions. Considerable phenotypic variation was found suggesting that this yeast employs diverse metabolic strategies to face environmental constraints. Several groups of strains can be distinguished from the entire population on the basis of specific traits. Strains accustomed to growing in the presence of high sugar concentrations, such as wine yeasts and strains obtained from fruits, were able to achieve fermentation, whereas natural yeasts isolated from “poor-sugar” environments, such as oak trees or plants, were not. Commercial wine yeasts clearly appeared as a subset of vineyard isolates, and were mainly differentiated by their fermentative performances as well as their low acetate production. Overall, the emergence of the origin-dependent properties of the strains provides evidence for a phenotypic evolution driven by environmental constraints and/or human selection within S. cerevisiae. PMID:21949874

  9. Genomic structural variation contributes to phenotypic change of industrial bioethanol yeast Saccharomyces cerevisiae.

    PubMed

    Zhang, Ke; Zhang, Li-Jie; Fang, Ya-Hong; Jin, Xin-Na; Qi, Lei; Wu, Xue-Chang; Zheng, Dao-Qiong

    2016-03-01

    Genomic structural variation (GSV) is a ubiquitous phenomenon observed in the genomes of Saccharomyces cerevisiae strains with different genetic backgrounds; however, the physiological and phenotypic effects of GSV are not well understood. Here, we first revealed the genetic characteristics of a widely used industrial S. cerevisiae strain, ZTW1, by whole genome sequencing. ZTW1 was identified as an aneuploidy strain and a large-scale GSV was observed in the ZTW1 genome compared with the genome of a diploid strain YJS329. These GSV events led to copy number variations (CNVs) in many chromosomal segments as well as one whole chromosome in the ZTW1 genome. Changes in the DNA dosage of certain functional genes directly affected their expression levels and the resultant ZTW1 phenotypes. Moreover, CNVs of large chromosomal regions triggered an aneuploidy stress in ZTW1. This stress decreased the proliferation ability and tolerance of ZTW1 to various stresses, while aneuploidy response stress may also provide some benefits to the fermentation performance of the yeast, including increased fermentation rates and decreased byproduct generation. This work reveals genomic characters of the bioethanol S. cerevisiae strain ZTW1 and suggests that GSV is an important kind of mutation that changes the traits of industrial S. cerevisiae strains. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. Switching the mode of metabolism in the yeast Saccharomyces cerevisiae

    PubMed Central

    Otterstedt, Karin; Larsson, Christer; Bill, Roslyn M; Ståhlberg, Anders; Boles, Eckhard; Hohmann, Stefan; Gustafsson, Lena

    2004-01-01

    The biochemistry of most metabolic pathways is conserved from bacteria to humans, although the control mechanisms are adapted to the needs of each cell type. Oxygen depletion commonly controls the switch from respiration to fermentation. However, Saccharomyces cerevisiae also controls that switch in response to the external glucose level. We have generated an S. cerevisiae strain in which glucose uptake is dependent on a chimeric hexose transporter mediating reduced sugar uptake. This strain shows a fully respiratory metabolism also at high glucose levels as seen for aerobic organisms, and switches to fermentation only when oxygen is lacking. These observations illustrate that manipulating a single step can alter the mode of metabolism. The novel yeast strain is an excellent tool to study the mechanisms underlying glucose-induced signal transduction. PMID:15071495

  11. Mitochondrial genomic dysfunction causes dephosphorylation of Sch9 in the yeast Saccharomyces cerevisiae.

    PubMed

    Kawai, Shigeyuki; Urban, Jörg; Piccolis, Manuele; Panchaud, Nicolas; De Virgilio, Claudio; Loewith, Robbie

    2011-10-01

    TORC1-dependent phosphorylation of Saccharomyces cerevisiae Sch9 was dramatically reduced upon exposure to a protonophore or in respiration-incompetent ρ(0) cells but not in respiration-incompetent pet mutants, providing important insight into the molecular mechanisms governing interorganellar signaling in general and retrograde signaling in particular.

  12. Screening for hydrolytic enzymes reveals Ayr1p as a novel triacylglycerol lipase in Saccharomyces cerevisiae.

    PubMed

    Ploier, Birgit; Scharwey, Melanie; Koch, Barbara; Schmidt, Claudia; Schatte, Jessica; Rechberger, Gerald; Kollroser, Manfred; Hermetter, Albin; Daum, Günther

    2013-12-13

    Saccharomyces cerevisiae, as well as other eukaryotes, preserves fatty acids and sterols in a biologically inert form, as triacylglycerols and steryl esters. The major triacylglycerol lipases of the yeast S. cerevisiae identified so far are Tgl3p, Tgl4p, and Tgl5p (Athenstaedt, K., and Daum, G. (2003) YMR313c/TGL3 encodes a novel triacylglycerol lipase located in lipid particles of Saccharomyces cerevisiae. J. Biol. Chem. 278, 23317-23323; Athenstaedt, K., and Daum, G. (2005) Tgl4p and Tgl5p, two triacylglycerol lipases of the yeast Saccharomyces cerevisiae, are localized to lipid particles. J. Biol. Chem. 280, 37301-37309). We observed that upon cultivation on oleic acid, triacylglycerol mobilization did not come to a halt in a yeast strain deficient in all currently known triacylglycerol lipases, indicating the presence of additional not yet characterized lipases/esterases. Functional proteome analysis using lipase and esterase inhibitors revealed a subset of candidate genes for yet unknown hydrolytic enzymes on peroxisomes and lipid droplets. Based on the conserved GXSXG lipase motif, putative functions, and subcellular localizations, a selected number of candidates were characterized by enzyme assays in vitro, gene expression analysis, non-polar lipid analysis, and in vivo triacylglycerol mobilization assays. These investigations led to the identification of Ayr1p as a novel triacylglycerol lipase of yeast lipid droplets and confirmed the hydrolytic potential of the peroxisomal Lpx1p in vivo. Based on these results, we discuss a possible link between lipid storage, lipid mobilization, and peroxisomal utilization of fatty acids as a carbon source.

  13. 40 CFR 180.1246 - Yeast Extract Hydrolysate from Saccharomyces cerevisiae: exemption from the requirement of a...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Hydrolysate from Saccharomyces cerevisiae on all food commodities when applied/used for the management of... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1246 Yeast Extract Hydrolysate from...

  14. Alkaline pH enhances farnesol production by Saccharomyces cerevisiae.

    PubMed

    Muramatsu, Masayoshi; Ohto, Chikara; Obata, Shusei; Sakuradani, Eiji; Shimizu, Sakayu

    2009-07-01

    External environments affect prenyl alcohol production by squalene synthetase-deficient mutant Saccharomyces cerevisiae ATCC 64031. Cultivation of the yeast in medium with an initial pH ranging from 7.0 to 8.0 increased the amount of secreted farnesol (FOH). In contrast, acidic medium with a pH below 4.0 increased the intracellular FOH and its isomer nerolidol. These effects of alkaline pH were also observed on constant pH cultivation in a jar fermenter. On cultivation for 133 h, the FOH production reached 102.8 mg/l.

  15. Induction of polypeptides in Saccharomyces cerevisiae after ultraviolet irradiation.

    PubMed

    Angulo, J F; Schwencke, J; Fernandez, I; Moustacchi, E

    1986-07-31

    Alterations in the synthesis of proteins following exposure of Saccharomyces cerevisiae to UV light were investigated using radioactive labelling and two dimensional electrophoresis. UV-irradiation induced the synthesis of various proteins. Among them the analogue of the RecA protein of Escherichia coli (Angulo et al. 1985) and two other polypeptides (34 Kd and 35 Kd, pI 5.8) were observed in all four strains analyzed namely two DNA-repair deficient (rad-) strains: (rad6-1 and pso2-1) and their isogenic wild type RAD+ strains.

  16. An oxalyl-CoA synthetase is important for oxalate metabolism in Saccharomyces cerevisiae

    USDA-ARS?s Scientific Manuscript database

    Although oxalic acid is common in nature, our understanding of the mechanism(s) regulating its turnover remains incomplete. In this study we identify Saccharomyces cerevisiae acyl-activating enzyme 3 (ScAAE3) as an enzyme capable of catalyzing the conversion of oxalate to oxalyl-CoA. Based on our fi...

  17. Ethanol-independent biofilm formation by a flor wine yeast strain of Saccharomyces cerevisiae.

    PubMed

    Zara, Severino; Gross, Michael K; Zara, Giacomo; Budroni, Marilena; Bakalinsky, Alan T

    2010-06-01

    Flor strains of Saccharomyces cerevisiae form a biofilm on the surface of wine at the end of fermentation, when sugar is depleted and growth on ethanol becomes dependent on oxygen. Here, we report greater biofilm formation on glycerol and ethyl acetate and inconsistent formation on succinic, lactic, and acetic acids.

  18. Acidic Calcium Stores of Saccharomyces cerevisiae

    PubMed Central

    Cunningham, Kyle W.

    2011-01-01

    Fungi and animals constitute sister kingdoms in the eukaryotic domain of life. The major classes of transporters, channels, sensors, and effectors that move and respond to calcium ions were already highly networked in the common ancestor of fungi and animals. Since that time, some key components of the network have been moved, altered, relocalized, lost, or duplicated in the fungal and animal lineages and at the same time some of the regulatory circuitry has been dramatically rewired. Today the calcium transport and signaling networks in fungi provide a fresh perspective on the scene that has emerged from studies of the network in animal cells. This review provides an overview of calcium signaling networks in fungi, particularly the model yeast Saccharomyces cerevisiae, with special attention to the dominant roles of acidic calcium stores in fungal cell physiology. PMID:21377728

  19. The Impact of Saccharomyces cerevisiae on a Wine Yeast Consortium in Natural and Inoculated Fermentations

    PubMed Central

    Bagheri, Bahareh; Bauer, Florian F.; Setati, Mathabatha E.

    2017-01-01

    Natural, also referred to as spontaneous wine fermentations, are carried out by the native microbiota of the grape juice, without inoculation of selected, industrially produced yeast or bacterial strains. Such fermentations are commonly initiated by non-Saccharomyces yeast species that numerically dominate the must. Community composition and numerical dominance of species vary significantly between individual musts, but Saccharomyces cerevisiae will in most cases dominate the late stages of the fermentation and complete the process. Nevertheless, non-Saccharomyces species contribute significantly, positively or negatively, to the character and quality of the final product. The contribution is species and strain dependent and will depend on each species or strain’s absolute and relative contribution to total metabolically active biomass, and will therefore, be a function of its relative fitness within the microbial ecosystem. However, the population dynamics of multispecies fermentations are not well understood. Consequently, the oenological potential of the microbiome in any given grape must, can currently not be evaluated or predicted. To better characterize the rules that govern the complex wine microbial ecosystem, a model yeast consortium comprising eight species commonly encountered in South African grape musts and an ARISA based method to monitor their dynamics were developed and validated. The dynamics of these species were evaluated in synthetic must in the presence or absence of S. cerevisiae using direct viable counts and ARISA. The data show that S. cerevisiae specifically suppresses certain species while appearing to favor the persistence of other species. Growth dynamics in Chenin blanc grape must fermentation was monitored only through viable counts. The interactions observed in the synthetic must, were upheld in the natural must fermentations, suggesting the broad applicability of the observed ecosystem dynamics. Importantly, the presence of

  20. The Impact of Saccharomyces cerevisiae on a Wine Yeast Consortium in Natural and Inoculated Fermentations.

    PubMed

    Bagheri, Bahareh; Bauer, Florian F; Setati, Mathabatha E

    2017-01-01

    Natural, also referred to as spontaneous wine fermentations, are carried out by the native microbiota of the grape juice, without inoculation of selected, industrially produced yeast or bacterial strains. Such fermentations are commonly initiated by non- Saccharomyces yeast species that numerically dominate the must. Community composition and numerical dominance of species vary significantly between individual musts, but Saccharomyces cerevisiae will in most cases dominate the late stages of the fermentation and complete the process. Nevertheless, non- Saccharomyces species contribute significantly, positively or negatively, to the character and quality of the final product. The contribution is species and strain dependent and will depend on each species or strain's absolute and relative contribution to total metabolically active biomass, and will therefore, be a function of its relative fitness within the microbial ecosystem. However, the population dynamics of multispecies fermentations are not well understood. Consequently, the oenological potential of the microbiome in any given grape must, can currently not be evaluated or predicted. To better characterize the rules that govern the complex wine microbial ecosystem, a model yeast consortium comprising eight species commonly encountered in South African grape musts and an ARISA based method to monitor their dynamics were developed and validated. The dynamics of these species were evaluated in synthetic must in the presence or absence of S. cerevisiae using direct viable counts and ARISA. The data show that S. cerevisiae specifically suppresses certain species while appearing to favor the persistence of other species. Growth dynamics in Chenin blanc grape must fermentation was monitored only through viable counts. The interactions observed in the synthetic must, were upheld in the natural must fermentations, suggesting the broad applicability of the observed ecosystem dynamics. Importantly, the presence of

  1. Saccharomyces cerevisiae expressing Gp43 protects mice against Paracoccidioides brasiliensis infection.

    PubMed

    Assis-Marques, Mariana Aprigio; Oliveira, Aline Ferreira; Ruas, Luciana Pereira; dos Reis, Thaila Fernanda; Roque-Barreira, Maria Cristina; Coelho, Paulo Sergio Rodrigues

    2015-01-01

    The dimorphic fungus Paracoccidioides brasiliensis is the etiological agent of paracoccidioidomycosis (PCM). It is believed that approximately 10 million people are infected with the fungus and approximately 2% will eventually develop the disease. Unlike viral and bacterial diseases, fungal diseases are the ones against which there is no commercially available vaccine. Saccharomyces cerevisiae may be a suitable vehicle for immunization against fungal infections, as they require the stimulation of different arms of the immune response. Here we evaluated the efficacy of immunizing mice against PCM by using S. cerevisiae yeast expressing gp43. When challenged by inoculation of P. brasiliensis yeasts, immunized animals showed a protective profile in three different assays. Their lung parenchyma was significantly preserved, exhibiting fewer granulomas with fewer fungal cells than found in non-immunized mice. Fungal burden was reduced in the lung and spleen of immunized mice, and both organs contained higher levels of IL-12 and IFN-γ compared to those of non-vaccinated mice, a finding that suggests the occurrence of Th1 immunity. Taken together, our results indicate that the recombinant yeast vaccine represents a new strategy to confer protection against PCM.

  2. Heterologous Expression of an Entamoeba histolytica Chitin Synthase in Saccharomyces cerevisiae

    PubMed Central

    Van Dellen, Katrina L.; Bulik, Dorota A.; Specht, Charles A.; Robbins, Phillips W.; Samuelson, John C.

    2006-01-01

    Chitin in the cyst wall of Entamoeba histolytica is made by two chitin synthases (Chs), one of which is unique (EhCHS-1) and one of which resembles those of insects and nematodes (EhCHS-2). EhCHS-1 is deposited chitin in the lateral wall of transformed Saccharomyces cerevisiae Chs mutants, independent of accessory proteins (Chs4p to Chs7p) required by yeast Chs3p. PMID:16400183

  3. Heterologous expression of an Entamoeba histolytica chitin synthase in Saccharomyces cerevisiae.

    PubMed

    Van Dellen, Katrina L; Bulik, Dorota A; Specht, Charles A; Robbins, Phillips W; Samuelson, John C

    2006-01-01

    Chitin in the cyst wall of Entamoeba histolytica is made by two chitin synthases (Chs), one of which is unique (EhCHS-1) and one of which resembles those of insects and nematodes (EhCHS-2). EhCHS-1 is deposited chitin in the lateral wall of transformed Saccharomyces cerevisiae Chs mutants, independent of accessory proteins (Chs4p to Chs7p) required by yeast Chs3p.

  4. Different effects of sodium chloride preincubation on cadmium tolerance of Pichia kudriavzevii and Saccharomyces cerevisiae.

    PubMed

    Ma, Ning; Li, Chunsheng; Dong, Xiaoyan; Wang, Dongfeng; Xu, Ying

    2015-08-01

    Application of growing microorganisms for cadmium removal is restricted by high cadmium toxicity. The effects of sodium chloride (NaCl) preincubation on the cadmium tolerance and removal ability of Pichia kudriavzevii and Saccharomyces cerevisiae were investigated in this study. NaCl preincubation improved the biomass of P. kudriavzevii under cadmium stress, while no obvious effect was observed in S. cerevisiae. The improved activities of peroxidase (POD) and catalase (CAT) after NaCl preincubation might be an important reason for the decrease of the reactive oxygen species (ROS) accumulation, cell death, and oxidative damage of proteins and lipids induced by cadmium, contributing to the improvement of the yeast growth. The cadmium bioaccumulation capacity of P. kudriavzevii decreased significantly after NaCl preincubation, which played an important role in mitigating the cadmium toxicity to the yeast. The cadmium removal rate of P. kudriavzevii was obviously higher than S. cerevisiae and was significantly enhanced after NaCl preincubation. The results suggested that NaCl preincubation improved the cadmium tolerance and removal ability of P. kudriavzevii. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Zinc oxide and silver nanoparticles toxicity in the baker's yeast, Saccharomyces cerevisiae.

    PubMed

    Galván Márquez, Imelda; Ghiyasvand, Mergan; Massarsky, Andrey; Babu, Mohan; Samanfar, Bahram; Omidi, Katayoun; Moon, Thomas W; Smith, Myron L; Golshani, Ashkan

    2018-01-01

    Engineered nanomaterials (ENMs) are increasingly incorporated into a variety of commercial applications and consumer products; however, ENMs may possess cytotoxic properties due to their small size. This study assessed the effects of two commonly used ENMs, zinc oxide nanoparticles (ZnONPs) and silver nanoparticles (AgNPs), in the model eukaryote Saccharomyces cerevisiae. A collection of ≈4600 S. cerevisiae deletion mutant strains was used to deduce the genes, whose absence makes S. cerevisiae more prone to the cytotoxic effects of ZnONPs or AgNPs. We demonstrate that S. cerevisiae strains that lack genes involved in transmembrane and membrane transport, cellular ion homeostasis, and cell wall organization or biogenesis exhibited the highest sensitivity to ZnONPs. In contrast, strains that lack genes involved in transcription and RNA processing, cellular respiration, and endocytosis and vesicular transport exhibited the highest sensitivity to AgNPs. Secondary assays confirmed that ZnONPs affected cell wall function and integrity, whereas AgNPs exposure decreased transcription, reduced endocytosis, and led to a dysfunctional electron transport system. This study supports the use of S. cerevisiae Gene Deletion Array as an effective high-throughput technique to determine cellular targets of ENM toxicity.

  6. Functional expression of a heterologous nickel-dependent, ATP-independent urease in Saccharomyces cerevisiae.

    PubMed

    Milne, N; Luttik, M A H; Cueto Rojas, H F; Wahl, A; van Maris, A J A; Pronk, J T; Daran, J M

    2015-07-01

    In microbial processes for production of proteins, biomass and nitrogen-containing commodity chemicals, ATP requirements for nitrogen assimilation affect product yields on the energy producing substrate. In Saccharomyces cerevisiae, a current host for heterologous protein production and potential platform for production of nitrogen-containing chemicals, uptake and assimilation of ammonium requires 1 ATP per incorporated NH3. Urea assimilation by this yeast is more energy efficient but still requires 0.5 ATP per NH3 produced. To decrease ATP costs for nitrogen assimilation, the S. cerevisiae gene encoding ATP-dependent urease (DUR1,2) was replaced by a Schizosaccharomyces pombe gene encoding ATP-independent urease (ure2), along with its accessory genes ureD, ureF and ureG. Since S. pombe ure2 is a Ni(2+)-dependent enzyme and Saccharomyces cerevisiae does not express native Ni(2+)-dependent enzymes, the S. pombe high-affinity nickel-transporter gene (nic1) was also expressed. Expression of the S. pombe genes into dur1,2Δ S. cerevisiae yielded an in vitro ATP-independent urease activity of 0.44±0.01 µmol min(-1) mg protein(-1) and restored growth on urea as sole nitrogen source. Functional expression of the Nic1 transporter was essential for growth on urea at low Ni(2+) concentrations. The maximum specific growth rates of the engineered strain on urea and ammonium were lower than those of a DUR1,2 reference strain. In glucose-limited chemostat cultures with urea as nitrogen source, the engineered strain exhibited an increased release of ammonia and reduced nitrogen content of the biomass. Our results indicate a new strategy for improving yeast-based production of nitrogen-containing chemicals and demonstrate that Ni(2+)-dependent enzymes can be functionally expressed in S. cerevisiae. Copyright © 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  7. Integrative proteomics and biochemical analyses define Ptc6p as the Saccharomyces cerevisiae pyruvate dehydrogenase phosphatase.

    PubMed

    Guo, Xiao; Niemi, Natalie M; Coon, Joshua J; Pagliarini, David J

    2017-07-14

    The pyruvate dehydrogenase complex (PDC) is the primary metabolic checkpoint connecting glycolysis and mitochondrial oxidative phosphorylation and is important for maintaining cellular and organismal glucose homeostasis. Phosphorylation of the PDC E1 subunit was identified as a key inhibitory modification in bovine tissue ∼50 years ago, and this regulatory process is now known to be conserved throughout evolution. Although Saccharomyces cerevisiae is a pervasive model organism for investigating cellular metabolism and its regulation by signaling processes, the phosphatase(s) responsible for activating the PDC in S. cerevisiae has not been conclusively defined. Here, using comparative mitochondrial phosphoproteomics, analyses of protein-protein interactions by affinity enrichment-mass spectrometry, and in vitro biochemistry, we define Ptc6p as the primary PDC phosphatase in S. cerevisiae Our analyses further suggest additional substrates for related S. cerevisiae phosphatases and describe the overall phosphoproteomic changes that accompany mitochondrial respiratory dysfunction. In summary, our quantitative proteomics and biochemical analyses have identified Ptc6p as the primary-and likely sole- S. cerevisiae PDC phosphatase, closing a key knowledge gap about the regulation of yeast mitochondrial metabolism. Our findings highlight the power of integrative omics and biochemical analyses for annotating the functions of poorly characterized signaling proteins. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. Ypq3p-dependent histidine uptake by the vacuolar membrane vesicles of Saccharomyces cerevisiae.

    PubMed

    Manabe, Kunio; Kawano-Kawada, Miyuki; Ikeda, Koichi; Sekito, Takayuki; Kakinuma, Yoshimi

    2016-06-01

    The vacuolar membrane proteins Ypq1p, Ypq2p, and Ypq3p of Saccharomyces cerevisiae are known as the members of the PQ-loop protein family. We found that the ATP-dependent uptake activities of arginine and histidine by the vacuolar membrane vesicles were decreased by ypq2Δ and ypq3Δ mutations, respectively. YPQ1 and AVT1, which are involved in the vacuolar uptake of lysine/arginine and histidine, respectively, were deleted in addition to ypq2Δ and ypq3Δ. The vacuolar membrane vesicles isolated from the resulting quadruple deletion mutant ypq1Δypq2Δypq3Δavt1Δ completely lost the uptake activity of basic amino acids, and that of histidine, but not lysine and arginine, was evidently enhanced by overexpressing YPQ3 in the mutant. These results suggest that Ypq3p is specifically involved in the vacuolar uptake of histidine in S. cerevisiae. The cellular level of Ypq3p-HA(3) was enhanced by depletion of histidine from culture medium, suggesting that it is regulated by the substrate.

  9. Integrated phospholipidomics and transcriptomics analysis of Saccharomyces cerevisiae with enhanced tolerance to a mixture of acetic acid, furfural, and phenol

    USDA-ARS?s Scientific Manuscript database

    A mixture of acetic acid, furfural and phenol (AFP), three representative lignocellulose derived inhibitors, significantly inhibited the growth and bioethanol production of Saccharomyces cerevisiae. In order to uncover mechanisms behind the enhanced tolerance of an inhibitor-tolerant S.cerevisiae s...

  10. Engineering and Evolution of Saccharomyces cerevisiae to Produce Biofuels and Chemicals.

    PubMed

    Turner, Timothy L; Kim, Heejin; Kong, In Iok; Liu, Jing-Jing; Zhang, Guo-Chang; Jin, Yong-Su

    To mitigate global climate change caused partly by the use of fossil fuels, the production of fuels and chemicals from renewable biomass has been attempted. The conversion of various sugars from renewable biomass into biofuels by engineered baker's yeast (Saccharomyces cerevisiae) is one major direction which has grown dramatically in recent years. As well as shifting away from fossil fuels, the production of commodity chemicals by engineered S. cerevisiae has also increased significantly. The traditional approaches of biochemical and metabolic engineering to develop economic bioconversion processes in laboratory and industrial settings have been accelerated by rapid advancements in the areas of yeast genomics, synthetic biology, and systems biology. Together, these innovations have resulted in rapid and efficient manipulation of S. cerevisiae to expand fermentable substrates and diversify value-added products. Here, we discuss recent and major advances in rational (relying on prior experimentally-derived knowledge) and combinatorial (relying on high-throughput screening and genomics) approaches to engineer S. cerevisiae for producing ethanol, butanol, 2,3-butanediol, fatty acid ethyl esters, isoprenoids, organic acids, rare sugars, antioxidants, and sugar alcohols from glucose, xylose, cellobiose, galactose, acetate, alginate, mannitol, arabinose, and lactose.

  11. Effects of Saccharomyces cerevisiae or boulardii yeasts on acute stress induced intestinal dysmotility.

    PubMed

    West, Christine; Stanisz, Andrew M; Wong, Annette; Kunze, Wolfgang A

    2016-12-28

    To investigate the capacity of Saccharomyces cerevisiae ( S. cerevisiae ) and Saccharomyces boulardii ( S. boulardii ) yeasts to reverse or to treat acute stress-related intestinal dysmotility. Adult Swiss Webster mice were stressed for 1 h in a wire-mesh restraint to induce symptoms of intestinal dysmotility and were subsequently killed by cervical dislocation. Jejunal and colon tissue were excised and placed within a tissue perfusion bath in which S. cerevisiae , S. boulardii , or their supernatants were administered into the lumen. Video recordings of contractility and gut diameter changes were converted to spatiotemporal maps and the velocity, frequency, and amplitude of propagating contractile clusters (PCC) were measured. Motility pre- and post-treatment was compared between stressed animals and unstressed controls. S. boulardii and S. cerevisiae helped to mediate the effects of stress on the small and large intestine. Restraint stress reduced jejunal transit velocity (mm/s) from 2.635 ± 0.316 to 1.644 ± 0.238, P < 0.001 and jejunal transit frequency (Hz) from 0.032 ± 0.008 to 0.016 ± 0.005, P < 0.001. Restraint stress increased colonic transit velocity (mm/s) from 0.864 ± 0.183 to 1.432 ± 0.329, P < 0.001 and frequency to a lesser degree. Luminal application of S. boulardii helped to restore jejunal and colonic velocity towards the unstressed controls; 1.833 ± 0.688 to 2.627 ± 0.664, P < 0.001 and 1.516 ± 0.263 to 1.036 ± 0.21, P < 0.001, respectively. S. cerevisiae also had therapeutic effects on the stressed gut, but was most apparent in the jejunum. S. cerevisiae increased PCC velocity in the stressed jejunum from 1.763 ± 0.397 to 2.017 ± 0.48, P = 0.0031 and PCC frequency from 0.016 ± 0.009 to 0.027 ± 0.007, P < 0.001. S. cerevisiae decreased colon PCC velocity from 1.647 ± 0.187 to 1.038 ± 0.222, P < 0.001. Addition of S. boulardii or S. cerevisiae supernatants also helped to restore motility to unstressed values in similar capacity

  12. Effects of Saccharomyces cerevisiae or boulardii yeasts on acute stress induced intestinal dysmotility

    PubMed Central

    West, Christine; Stanisz, Andrew M; Wong, Annette; Kunze, Wolfgang A

    2016-01-01

    AIM To investigate the capacity of Saccharomyces cerevisiae (S. cerevisiae) and Saccharomyces boulardii (S. boulardii) yeasts to reverse or to treat acute stress-related intestinal dysmotility. METHODS Adult Swiss Webster mice were stressed for 1 h in a wire-mesh restraint to induce symptoms of intestinal dysmotility and were subsequently killed by cervical dislocation. Jejunal and colon tissue were excised and placed within a tissue perfusion bath in which S. cerevisiae, S. boulardii, or their supernatants were administered into the lumen. Video recordings of contractility and gut diameter changes were converted to spatiotemporal maps and the velocity, frequency, and amplitude of propagating contractile clusters (PCC) were measured. Motility pre- and post-treatment was compared between stressed animals and unstressed controls. RESULTS S. boulardii and S. cerevisiae helped to mediate the effects of stress on the small and large intestine. Restraint stress reduced jejunal transit velocity (mm/s) from 2.635 ± 0.316 to 1.644 ± 0.238, P < 0.001 and jejunal transit frequency (Hz) from 0.032 ± 0.008 to 0.016 ± 0.005, P < 0.001. Restraint stress increased colonic transit velocity (mm/s) from 0.864 ± 0.183 to 1.432 ± 0.329, P < 0.001 and frequency to a lesser degree. Luminal application of S. boulardii helped to restore jejunal and colonic velocity towards the unstressed controls; 1.833 ± 0.688 to 2.627 ± 0.664, P < 0.001 and 1.516 ± 0.263 to 1.036 ± 0.21, P < 0.001, respectively. S. cerevisiae also had therapeutic effects on the stressed gut, but was most apparent in the jejunum. S. cerevisiae increased PCC velocity in the stressed jejunum from 1.763 ± 0.397 to 2.017 ± 0.48, P = 0.0031 and PCC frequency from 0.016 ± 0.009 to 0.027 ± 0.007, P < 0.001. S. cerevisiae decreased colon PCC velocity from 1.647 ± 0.187 to 1.038 ± 0.222, P < 0.001. Addition of S. boulardii or S. cerevisiae supernatants also helped to restore motility to unstressed values in similar

  13. Thiamin biosynthesis in Saccharomyces cerevisiae. Origin of carbon-2 of the thiazole moiety.

    PubMed Central

    White, R L; Spenser, I D

    1979-01-01

    Radioactivity from [2-14C]glycine enters C-2 of the thiazole moiety of thiamin and no other site, in Saccharomyces cerevisiae (strains A.T.C.C. 24903 and 39916, H.J. Bunker). Radioactivity from L-[Me-14C]methionine or from DL-[2-14C]tyrosine does not enter thiamin. PMID:384994

  14. Lachancea thermotolerans and Saccharomyces cerevisiae in simultaneous and sequential co-fermentation: a strategy to enhance acidity and improve the overall quality of wine.

    PubMed

    Gobbi, Mirko; Comitini, Francesca; Domizio, Paola; Romani, Cristina; Lencioni, Livio; Mannazzu, Ilaria; Ciani, Maurizio

    2013-04-01

    In the last few years there is an increasing interest on the use of mixed fermentation of Saccharomyces and non-Saccharomyces wine yeasts for inoculation of wine fermentations to enhance the quality and improve complexity of wines. In the present work Lachancea (Kluyveromyces) thermotolerans and Saccharomyces cerevisiae were evaluated in simultaneous and sequential fermentation with the aim to enhance acidity and improve the quality of wine. In this specific pairing of yeast strains in mixed fermentations (S. cerevisiae EC1118 and L. thermotolerans 101), this non-Saccharomyces yeast showed a high level of competitiveness. Nevertheless the S. cerevisiae strain dominated the fermentation over the spontaneous S. cerevisiae strains also under the industrial fermentation conditions. The different condition tested (modalities of inoculum, temperature of fermentation, different grape juice) influenced the specific interactions and the fermentation behaviour of the co-culture of S. cerevisiae and L. thermotolerans. However, some metabolic behaviours such as pH reduction and enhancement of 2-phenylethanol and glycerol, were shown here under all of the conditions tested. The specific chemical profiles of these wines were confirmed by the sensory analysis test, which expressed these results at the tasting level as significant increases in the spicy notes and in terms of total acidity increases. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Isolation and characterization of a resident tolerant Saccharomyces cerevisiae strain from a spent sulfite liquor fermentation plant

    PubMed Central

    2012-01-01

    Spent Sulfite Liquor (SSL) from wood pulping facilities is a sugar rich effluent that can be used as feedstock for ethanol production. However, depending on the pulping process conditions, the release of monosaccharides also generates a range of compounds that negatively affect microbial fermentation. In the present study, we investigated whether endogenous yeasts in SSL-based ethanol plant could represent a source of Saccharomyces cerevisiae strains with a naturally acquired tolerance towards this inhibitory environment. Two isolation processes were performed, before and after the re-inoculation of the plant with a commercial baker’s yeast strain. The isolates were clustered by DNA fingerprinting and a recurrent Saccharomyces cerevisiae strain, different from the inoculated commercial baker’s yeast strain, was isolated. The strain, named TMB3720, flocculated heavily and presented high furaldehyde reductase activity. During fermentation of undiluted SSL, TMB3720 displayed a 4-fold higher ethanol production rate and 1.8-fold higher ethanol yield as compared to the commercial baker’s yeast. Another non-Saccharomyces cerevisiae species, identified as the pentose utilizing Pichia galeiformis, was also recovered in the last tanks of the process where the hexose to pentose sugar ratio and the inhibitory pressure are expected to be the lowest. PMID:23237549

  16. Metabolic construction strategies for direct methanol utilization in Saccharomyces cerevisiae.

    PubMed

    Dai, Zhongxue; Gu, Honglian; Zhang, Shangjie; Xin, Fengxue; Zhang, Wenming; Dong, Weiliang; Ma, Jiangfeng; Jia, Honghua; Jiang, Min

    2017-12-01

    The aim of this study was to metabolically construct Saccharomyces cerevisiae for achievement of direct methanol utilization and value added product (mainly pyruvate) production. After successful integration of methanol oxidation pathway originated from Pichia pastoris into the chromosome of S. cerevisiae, the recombinant showed 1.04g/L consumption of methanol and 3.13% increase of cell growth (OD 600 ) when using methanol as the sole carbon source. Moreover, 0.26g/L of pyruvate was detected in the fermentation broth. The supplementation of 1g/L yeast extract could further improve cell growth with increase of 11.70% and methanol consumption to 2.35g/L. This represents the first genetically modified non-methylotrophic eukaryotic microbe for direct methanol utilization and would be of great value concerning the development of biotechnological processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Expression of monellin in a food-grade delivery system in Saccharomyces cerevisiae.

    PubMed

    Liu, Jun; Yan, Da-zhong; Zhao, Sheng-jun

    2015-10-01

    Genetically modified (GM) foods have caused much controversy. Construction of a food-grade delivery system is a desirable technique with presumptive impact on industrial applications from the perspective of bio-safety. The aim of this study was to construct a food-grade delivery system for Saccharomyces cerevisiae and to study the expression of monellin from the berries of the West African forest plant Dioscoreophyllum cumminsii in this system. A food-grade system for S. cerevisiae was constructed based on ribosomal DNA (rDNA)-mediated homologous recombination to enable high-copy-number integration of the expression cassette inserted into the rDNA locus. A copper resistance gene (CUP1) was used as the selection marker for yeast transformation. Because variants of transformants containing different copy numbers at the CUP1 locus can be readily selected after growth in the presence of elevated copper levels, we suggest that this system would prove useful in the generation of tandemly iterated gene clusters. Using this food-grade system, a single-chain monellin gene was heterologously expressed. The yield of monellin reached a maximum of 675 mg L(-1) . This system harbors exclusively S. cerevisiae DNA with no antibiotic resistance genes, and it should therefore be appropriate for safe use in the food industry. Monellin was shown to be expressed in this food-grade delivery system. To our knowledge, this is the first report so far on expression of monellin in a food-grade expression system in S. cerevisiae. © 2014 Society of Chemical Industry.

  18. Expression and purification of human and Saccharomyces cerevisiae equilibrative nucleoside transporters.

    PubMed

    Boswell-Casteel, Rebba C; Johnson, Jennifer M; Roe-Žurž, Zygy; Duggan, Kelli D; Schmitz, Hannah; Hays, Franklin A

    2018-02-01

    Nucleosides play an essential role in the physiology of eukaryotes by acting as metabolic precursors in de novo nucleic acid synthesis and energy metabolism. Nucleosides also act as ligands for purinergic receptors. Equilibrative nucleoside transporters (ENTs) are polytopic integral membrane proteins that aid in regulating plasmalemmal flux of purine and pyrimidine nucleosides and nucleobases. ENTs exhibit broad substrate selectivity across different isoforms and utilize diverse mechanisms to drive substrate flux across membranes. However, the molecular mechanisms and chemical determinants of ENT-mediated substrate recognition, binding, inhibition, and transport are poorly understood. To determine how ENT-mediated transport occurs at the molecular level, greater chemical insight and assays employing purified protein are essential. This article focuses on the expression and purification of human ENT1, human ENT2, and Saccharomyces cerevisiae ScENT1 using novel expression and purification strategies to isolate recombinant ENTs. ScENT1, hENT1, and hENT2 were expressed in W303 Saccharomyces cerevisiae cells and detergent solubilized from the membrane. After detergent extraction, these ENTs were further purified using immobilized metal affinity chromatography and size exclusion chromatography. This effort resulted in obtaining quantities of purified protein sufficient for future biophysical analysis. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Improved bread-baking process using Saccharomyces cerevisiae displayed with engineered cyclodextrin glucanotransferase.

    PubMed

    Shim, Jae-Hoon; Seo, Nam-Seok; Roh, Sun-Ah; Kim, Jung-Wan; Cha, Hyunju; Park, Kwan-Hwa

    2007-06-13

    A bread-baking process was developed using a potential novel enzyme, cyclodextrin glucanotransferase[3-18] (CGTase[3-18]), that had previously been engineered to have enhanced hydrolyzing activity with little cyclodextrin (CD) formation activity toward starch. CGTase[3-18] was primarily manipulated to be displayed on the cell surface of Saccharomyces cerevisiae. S. cerevisiae carrying pdeltaCGT integrated into the chromosome exhibited starch-hydrolyzing activity at the same optimal pH and temperature as the free enzyme. Volumes of the bread loaves and rice cakes prepared using S. cerevisiae/pdeltaCGT increased by 20% and 45%, respectively, with no detectable CD. Retrogradation rates of the bread and rice cakes decreased significantly during storage. In comparison to the wild type, S. cerevisiae/pdeltaCGT showed improved viability during four freeze-thaw cycles. The results indicated that CGTase[3-18] displayed on the surface of yeast hydrolyzed starch to glucose and maltose that can be used more efficiently for yeast fermentation. Therefore, display of an antistaling enzyme on the cell surface of yeast has potential for enhancing the baking process.

  20. Enhanced kefiran production by mixed culture of Lactobacillus kefiranofaciens and Saccharomyces cerevisiae.

    PubMed

    Cheirsilp, Benjamas; Shimizu, Hiroshi; Shioya, Suteaki

    2003-01-09

    In a batch mixed culture of Lactobacillus kefiranofaciens and Saccharomyces cerevisiae, which could assimilate lactic acid, cell growth and kefiran production rates of L. kefiranofaciens significantly increased, compared with those in pure cultures. The kefiran production rate was 36 mg l(-1) h(-1) in the mixed culture under the anaerobic condition, which was greater than that in the pure culture (24 mg l(-1) h(-1)). Under the aerobic condition, a more intensive interaction between these two strains was observed and higher kefiran production rate (44 mg l(-1) h(-1)) was obtained compared with that under the anaerobic condition. Kefiran production was further enhanced by an addition of fresh medium in the fed-batch mixed culture. In the fed-batch mixed culture, a final kefiran concentration of 5.41 g l(-1) was achieved at 87 h, thereby attaining the highest productivity at 62 mg l(-1) h(-1). Simulation study considered the reduction of lactic acid in pure culture was performed to estimate the additional effect of coculture with S. cerevisiae. Slightly higher cell growth and kefiran production rates in the mixed culture than those expected from pure culture by simulation were observed. These results suggest that coculture of L. kefiranofaciens and S. cerevisiae not only reduces the lactic acid concentration by consumption but also stimulates cell growth and kefiran production of L. kefiranofaciens.

  1. Genetic dissection of acetic acid tolerance in Saccharomyces cerevisiae.

    PubMed

    Geng, Peng; Xiao, Yin; Hu, Yun; Sun, Haiye; Xue, Wei; Zhang, Liang; Shi, Gui-Yang

    2016-09-01

    Dissection of the hereditary architecture underlying Saccharomyces cerevisiae tolerance to acetic acid is essential for ethanol fermentation. In this work, a genomics approach was used to dissect hereditary variations in acetic acid tolerance between two phenotypically different strains. A total of 160 segregants derived from these two strains were obtained. Phenotypic analysis indicated that the acetic acid tolerance displayed a normal distribution in these segregants, and suggested that the acetic acid tolerant traits were controlled by multiple quantitative trait loci (QTLs). Thus, 220 SSR markers covering the whole genome were used to detect QTLs of acetic acid tolerant traits. As a result, three QTLs were located on chromosomes 9, 12, and 16, respectively, which explained 38.8-65.9 % of the range of phenotypic variation. Furthermore, twelve genes of the candidates fell into the three QTL regions by integrating the QTL analysis with candidates of acetic acid tolerant genes. These results provided a novel avenue to obtain more robust strains.

  2. Enhanced isoprenoid production from xylose by engineered Saccharomyces cerevisiae.

    PubMed

    Kwak, Suryang; Kim, Soo Rin; Xu, Haiqing; Zhang, Guo-Chang; Lane, Stephan; Kim, Heejin; Jin, Yong-Su

    2017-11-01

    Saccharomyces cerevisiae has limited capabilities for producing fuels and chemicals derived from acetyl-CoA, such as isoprenoids, due to a rigid flux partition toward ethanol during glucose metabolism. Despite numerous efforts, xylose fermentation by engineered yeast harboring heterologous xylose metabolic pathways was not as efficient as glucose fermentation for producing ethanol. Therefore, we hypothesized that xylose metabolism by engineered yeast might be a better fit for producing non-ethanol metabolites. We indeed found that engineered S. cerevisiae on xylose showed higher expression levels of the enzymes involved in ethanol assimilation and cytosolic acetyl-CoA synthesis than on glucose. When genetic perturbations necessary for overproducing squalene and amorphadiene were introduced into engineered S. cerevisiae capable of fermenting xylose, we observed higher titers and yields of isoprenoids under xylose than glucose conditions. Specifically, co-overexpression of a truncated HMG1 (tHMG1) and ERG10 led to substantially higher squalene accumulation under xylose than glucose conditions. In contrast to glucose utilization producing massive amounts of ethanol regardless of aeration, xylose utilization allowed much less amounts of ethanol accumulation, indicating ethanol is simultaneously re-assimilated with xylose consumption and utilized for the biosynthesis of cytosolic acetyl-CoA. In addition, xylose utilization by engineered yeast with overexpression of tHMG1, ERG10, and ADS coding for amorphadiene synthase, and the down-regulation of ERG9 resulted in enhanced amorphadiene production as compared to glucose utilization. These results suggest that the problem of the rigid flux partition toward ethanol production in yeast during the production of isoprenoids and other acetyl-CoA derived chemicals can be bypassed by using xylose instead of glucose as a carbon source. Biotechnol. Bioeng. 2017;114: 2581-2591. © 2017 Wiley Periodicals, Inc. © 2017 Wiley

  3. Cellular and molecular engineering of yeast Saccharomyces cerevisiae for advanced biobutanol production.

    PubMed

    Kuroda, Kouichi; Ueda, Mitsuyoshi

    2016-02-01

    Butanol is an attractive alternative energy fuel owing to several advantages over ethanol. Among the microbial hosts for biobutanol production, yeast Saccharomyces cerevisiae has a great potential as a microbial host due to its powerful genetic tools, a history of successful industrial use, and its inherent tolerance to higher alcohols. Butanol production by S. cerevisiae was first attempted by transferring the 1-butanol-producing metabolic pathway from native microorganisms or using the endogenous Ehrlich pathway for isobutanol synthesis. Utilizing alternative enzymes with higher activity, eliminating competitive pathways, and maintaining cofactor balance achieved significant improvements in butanol production. Meeting future challenges, such as enhancing butanol tolerance and implementing a comprehensive strategy by high-throughput screening, would further elevate the biobutanol-producing ability of S. cerevisiae toward an ideal microbial cell factory exhibiting high productivity of biobutanol. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Screening for Hydrolytic Enzymes Reveals Ayr1p as a Novel Triacylglycerol Lipase in Saccharomyces cerevisiae*

    PubMed Central

    Ploier, Birgit; Scharwey, Melanie; Koch, Barbara; Schmidt, Claudia; Schatte, Jessica; Rechberger, Gerald; Kollroser, Manfred; Hermetter, Albin; Daum, Günther

    2013-01-01

    Saccharomyces cerevisiae, as well as other eukaryotes, preserves fatty acids and sterols in a biologically inert form, as triacylglycerols and steryl esters. The major triacylglycerol lipases of the yeast S. cerevisiae identified so far are Tgl3p, Tgl4p, and Tgl5p (Athenstaedt, K., and Daum, G. (2003) YMR313c/TGL3 encodes a novel triacylglycerol lipase located in lipid particles of Saccharomyces cerevisiae. J. Biol. Chem. 278, 23317–23323; Athenstaedt, K., and Daum, G. (2005) Tgl4p and Tgl5p, two triacylglycerol lipases of the yeast Saccharomyces cerevisiae, are localized to lipid particles. J. Biol. Chem. 280, 37301–37309). We observed that upon cultivation on oleic acid, triacylglycerol mobilization did not come to a halt in a yeast strain deficient in all currently known triacylglycerol lipases, indicating the presence of additional not yet characterized lipases/esterases. Functional proteome analysis using lipase and esterase inhibitors revealed a subset of candidate genes for yet unknown hydrolytic enzymes on peroxisomes and lipid droplets. Based on the conserved GXSXG lipase motif, putative functions, and subcellular localizations, a selected number of candidates were characterized by enzyme assays in vitro, gene expression analysis, non-polar lipid analysis, and in vivo triacylglycerol mobilization assays. These investigations led to the identification of Ayr1p as a novel triacylglycerol lipase of yeast lipid droplets and confirmed the hydrolytic potential of the peroxisomal Lpx1p in vivo. Based on these results, we discuss a possible link between lipid storage, lipid mobilization, and peroxisomal utilization of fatty acids as a carbon source. PMID:24187129

  5. 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.

  6. Advances in metabolic engineering of yeast Saccharomyces cerevisiae for production of chemicals.

    PubMed

    Borodina, Irina; Nielsen, Jens

    2014-05-01

    Yeast Saccharomyces cerevisiae is an important industrial host for production of enzymes, pharmaceutical and nutraceutical ingredients and recently also commodity chemicals and biofuels. Here, we review the advances in modeling and synthetic biology tools and how these tools can speed up the development of yeast cell factories. We also present an overview of metabolic engineering strategies for developing yeast strains for production of polymer monomers: lactic, succinic, and cis,cis-muconic acids. S. cerevisiae has already firmly established itself as a cell factory in industrial biotechnology and the advances in yeast strain engineering will stimulate development of novel yeast-based processes for chemicals production. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Molecular cloning and expression in Saccharomyces cerevisiae of two Aspergillus nidulans xylanase genes.

    PubMed Central

    Pérez-Gonzalez, J A; De Graaff, L H; Visser, J; Ramón, D

    1996-01-01

    Two Aspergillus nidulans genes, xlnA and xlnB, encoding the X22 and X24 xylanases from this fungus, respectively, have been cloned and sequenced. Their cDNAs have been expressed in a laboratory Saccharomyces cerevisiae strain under the control of a constitutive yeast promoter, resulting in the construction of recombinant xylanolytic yeast strains. PMID:8787417

  8. Biosorption of the strontium ion by irradiated Saccharomyces cerevisiae under culture conditions.

    PubMed

    Qiu, Liang; Feng, Jundong; Dai, Yaodong; Chang, Shuquan

    2017-06-01

    As a new-emerging method for strontium disposal, biosorption has shown advantages such as high sorption capacity; low cost. In this study, we investigated the potential of Saccharomyces cerevisiae (S. cerevisiae) in strontium disposal under culture conditions and the effects of irradiation on their biosorption capabilities. We found that S. cerevisiae can survive irradiation and grow. Pre-exposure to irradiation rendered S. cerevisiae resistant to further irradiation. Surprisingly, the pre-exposure to irradiation can increase the biosorption capability of S. cerevisiae. We further investigated the factors that influenced the biosorption efficiency, which were (strongest to weakest): pH > strontium concentration > time > temperature. In our orthogonal experiment, the optimal conditions for strontium biosorption by irradiated S. cerevisiae were: pH 7, 150 mg L -1 strontium at the temperature of 32 °C with 30 h. The equilibrium of strontium biosorption was analyzed by Langmuir and Freundlich models, from which the formal model is found to provide a better fit for the experimental results. The kinetics of strontium biosorption by living irradiated S. cerevisiae was found to be comprised of three phases: dramatically increased during 0-9 h, decreased during 12-24 h, and increased during 30-50 h. These results provide a systematic understanding of the biosorption capabilities of irradiated S. cerevisiae, which can contribute to the development of remediating nuclear waste water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Use of Torulaspora delbrueckii Co-fermentation With Two Saccharomyces cerevisiae Strains With Different Aromatic Characteristic to Improve the Diversity of Red Wine Aroma Profile

    PubMed Central

    Zhang, Bo-Qin; Luan, Yu; Duan, Chang-Qing; Yan, Guo-Liang

    2018-01-01

    The use of selected Saccharomyces and non-Saccharomyces strains as mixed starters has advantages over pure fermentation due to achieving wine products with distinctive and diversified aroma expected by consumers. To obtain a way to improve the aroma diversity and increase the differentiation of wine product, in this study, the aromatic effect of multi-culture of indigenous Torulaspora delbrueckii (TD12), simultaneous and sequential inoculation with two Saccharomyces strains (indigenous icewine yeast SC45 and commercial yeast BDX) with different enological characteristics were investigated in laboratory-scale 20 L fermenter, respectively. The results showed that T. delbrueckii co-fermented with different S. cerevisiae strain could generate diversified physicochemical and aromatic quality of wine as evidenced by PCA. Mixed fermentation of SC45/TD12 produced higher contents of higher alcohol (3-methyl-1-pentanol and phenylethyl alcohol), ethyl esters (ethyl decanoate and ethyl butanoate), terpenes and phenylacetaldehyde with less fatty acids (hexanoic acid, octanoic acid) and acetic acid, while BDX/TD12 generated more C6 alcohol (1-hexanol) and acetate esters (ethyl acetate and isoamyl acetate). Compared to simultaneous inoculation, sequential inoculation could achieve higher aroma diversity, and generate higher intensity of fruity, flowery and sweet attributes of wine as assessed by calculating the odor activity values. The different S. cerevisiae strain and inoculation method in alcoholic fermentation could further influence the formations of aromatic compounds in malolactic fermentation. Our results highlighted the importance of S. cerevisiae strain in shaping the aromatic quality of wine in mixed fermentation, and also suggested that using different S. cerevisiae strains with distinct aromatic characteristics co-fermentation with specific non-Saccharomyces strain is a potential way to increase the aromatic diversity and quality of wine product, which could provide

  10. Evaluation of Saccharomyces cerevisiae as an antiaflatoxicogenic agent in broiler feedstuffs.

    PubMed

    Pizzolitto, R P; Armando, M R; Salvano, M A; Dalcero, A M; Rosa, C A

    2013-06-01

    Aflatoxins (AF) are the most important mycotoxins produced by toxigenic strains of various Aspergillus spp. Biological decontamination of mycotoxins using microorganisms is a well-known strategy for the management of mycotoxins in feeds. Saccharomyces cerevisiae strains have been reported to bind aflatoxin B1 (AFB1). The aim of this study was to evaluate the ability of S. cerevisiae CECT 1891 in counteracting the deleterious effects of AFB1 in broiler chicks. Experimental aflatoxicosis was induced in 6-d-old broilers by feeding them 1.2 mg of AFB1/kg of feed for 3 wk, and the yeast strain was administrated in feed (10(10) cells/kg), in the drinking water (5 × 10(9) cells/L), or a combination of both treatments. A total of 160 chicks were randomly divided into 8 treatments (4 repetitions per treatment). Growth performance was measured weekly from d 7 to 28, and serum biochemical parameters, weights, and histopathological examination of livers were determined at d 28. The AFB1 significantly decreased the BW gain, feed intake, and impaired feed conversion rate. Moreover, AFB1 treatment decreased serum protein concentration and increased liver damage. The addition of S. cerevisiae strain to drinking water, to diets contaminated with AFB1, showed a positive protection effect on the relative weight of the liver, histopathology, and biochemical parameters. Furthermore, dietary addition of the yeast strain to drinking water alleviated the negative effects of AFB1 on growth performance parameters. In conclusion, this study suggests that in feed contaminated with AFB1, the use of S. cerevisiae is an alternative method to reduce the adverse effects of aflatoxicosis. Thus, apart from its excellent nutritional value, yeast can also be used as a mycotoxin adsorbent.

  11. Pathways and Mechanisms that Prevent Genome Instability in Saccharomyces cerevisiae

    PubMed Central

    Putnam, Christopher D.; Kolodner, Richard D.

    2017-01-01

    Genome rearrangements result in mutations that underlie many human diseases, and ongoing genome instability likely contributes to the development of many cancers. The tools for studying genome instability in mammalian cells are limited, whereas model organisms such as Saccharomyces cerevisiae are more amenable to these studies. Here, we discuss the many genetic assays developed to measure the rate of occurrence of Gross Chromosomal Rearrangements (called GCRs) in S. cerevisiae. These genetic assays have been used to identify many types of GCRs, including translocations, interstitial deletions, and broken chromosomes healed by de novo telomere addition, and have identified genes that act in the suppression and formation of GCRs. Insights from these studies have contributed to the understanding of pathways and mechanisms that suppress genome instability and how these pathways cooperate with each other. Integrated models for the formation and suppression of GCRs are discussed. PMID:28684602

  12. Saccharomyces cerevisiae variety diastaticus friend or foe?-spoilage potential and brewing ability of different Saccharomyces cerevisiae variety diastaticus yeast isolates by genetic, phenotypic and physiological characterization.

    PubMed

    Meier-Dörnberg, Tim; Kory, Oliver Ingo; Jacob, Fritz; Michel, Maximilian; Hutzler, Mathias

    2018-06-01

    Saccharomyces cerevisiae variety diastaticus is generally considered to be an obligatory spoilage microorganism and spoilage yeast in beer and beer-mixed beverages. Their super-attenuating ability causes increased carbon dioxide concentrations, beer gushing and potential bottle explosion along with changes in flavor, sedimentation and increased turbidity. This research shows clear differences in the super-attenuating properties of S. cerevisiae var. diastaticus yeast strains and their potential for industrial brewing applications. Nineteen unknown spoilage yeast cultures were obtained as isolates and characterized using a broad spectrum of genetic and phenotypic methods. Results indicated that all isolates represent genetically different S. cerevisiae var. diastaticus strains except for strain TUM PI BA 124. Yeast strains were screened for their super-attenuating ability and sporulation. Even if the STA1 gene responsible for super-attenuation by encoding for the enzyme glucoamylase could be verified by real-time polymerase chain reaction, no correlation to the spoilage potential could be demonstrated. Seven strains were further characterized focusing on brewing and sensory properties according to the yeast characterization platform developed by Meier-Dörnberg. Yeast strain TUM 3-H-2 cannot metabolize dextrin and soluble starch and showed no spoilage potential or super-attenuating ability even when the strain belongs to the species S. cerevisiae var. diastaticus. Overall, the beer produced with S. cerevisiae var. diastaticus has a dry and winey body with noticeable phenolic off-flavors desirable in German wheat beers.

  13. Isolation of peroxisome-deficient mutants of Saccharomyces cerevisiae.

    PubMed Central

    Erdmann, R; Veenhuis, M; Mertens, D; Kunau, W H

    1989-01-01

    Two mutants of Saccharomyces cerevisiae affected in peroxisomal assembly (pas mutants) have been isolated and characterized. Each strain contains a single mutation that results in (i) the inability to grow on oleic acid, (ii) accumulation of peroxisomal matrix enzymes in the cytosol, and (iii) absence of detectable peroxisomes at the ultrastructural level. These lesions (pas1-1 and pas2) are shown to be nonallelic and recessive. Crossing of pas1-1 and pas2 strains resulted in diploid cells that had regained the ability to grow on oleic acid as sole carbon source and to form peroxisomes. These pas mutants may provide useful tools for future studies on the molecular mechanisms involved in peroxisomal assembly. Images PMID:2568633

  14. Mechanisms of appearance of the Pasteur effect in Saccharomyces cerevisiae: inactivation of sugar transport systems.

    PubMed

    Lagunas, R; Dominguez, C; Busturia, A; Sáez, M J

    1982-10-01

    Saccharomyces cerevisiae does not show a noticeable Pasteur effect (activation of sugar catabolism by anaerobiosis) when growing with an excess of sugar and nitrogen source, but it does do so after exhaustion of the nitrogen source in the medium (resting state). We have found that this different behavior of growing and resting S. cerevisiae seems due to differences in the contribution of respiration to catabolism under both states. Growing S. cerevisiae respired only 3 to 20% of the catabolized sugar, depending on the sugar present; the remainder was fermented. In contrast, resting S. cerevisiae respired as much as 25 to 100% of the catabolized sugar. These results suggest that a shift to anaerobiosis would have much greater energetic consequences in resting than in growing S. cerevisiae. In resting S. cerevisiae anaerobiosis would strongly decrease the formation of ATP; as a consequence, various regulatory mechanisms would switch on, producing the observed increase of the rate of glycolysis. The greater significance that respiration reached in resting cells was not due to an increase of the respiratory capacity itself, but to a loss of fermentation which turned respiration into the main catabolic pathway. The main mechanism involved in the loss of fermentation observed during nitrogen starvation was a progressive inactivation of the sugar transport systems that reduced the rate of fermentation to less than 10% of the value observed in growing cells. Inactivation of the sugar transports seems a consequence of the turnover of the sugar carriers whose apparent half-lives were 2 to 7 h.

  15. Cloning and expression of two chitin deacetylase genes of Saccharomyces cerevisiae.

    PubMed

    Mishra, C; Semino, C E; McCreath, K J; de la Vega, H; Jones, B J; Specht, C A; Robbins, P W

    1997-03-30

    Chitin deacetylase (EC 3.5.1.41), which hydrolyses the N-acetamido groups of N-acetyl-D-glucosamine residues in chitin, has been demonstrated in crude extracts from sporulating Saccharomyces cerevisiae. Two S. cerevisiae open reading frames (ORFs), identified by the Yeast Genome Project, have protein sequence homology to a chitin deacetylase from Mucor rouxii. Northern blot hybridizations show each ORF was transcribed in diploid cells after transfer to sporulation medium and prior to formation of asci. Each ORF was cloned in a vector under transcriptional control of the GAL 1, 10 promoter and introduced back into haploid strains of S. cerevisiae. Chitin deacetylase activity was detected by in vitro assays from vegetative cells grown in galactose. Chemical analysis of these cells also demonstrated the synthesis of chitosam in vivo. Both recombinant chitin deacetylases showed similar qualitative and quantitative activities toward chitooligosaccharides in vitro. A diploid strain deleted to both ORFs, when sporulated, did not show deacetylase activity. The mutant spores were hypersensitive to lytic enzymes (Glusulase or Zymolyase).

  16. Biosynthesis and engineering of kaempferol in Saccharomyces cerevisiae.

    PubMed

    Duan, Lijin; Ding, Wentao; Liu, Xiaonan; Cheng, Xiaozhi; Cai, Jing; Hua, Erbing; Jiang, Huifeng

    2017-09-26

    Kaempferol is a flavonol with broad bioactivity of anti-oxidant, anti-cancer, anti-diabetic, anti-microbial, cardio-protective and anti-asthma. Microbial synthesis of kaempferol is a promising strategy because of the low content in primary plant source. In this study, the biosynthesis pathway of kaempferol was constructed in the budding yeast Saccharomyces cerevisiae to produce kaempferol de novo, and several biological measures were taken for high production. Firstly, a high efficient flavonol synthases (FLS) from Populus deltoides was introduced into the biosynthetic pathway of kaempferol. Secondly, a S. cerevisiae recombinant was constructed for de novo synthesis of kaempferol, which generated about 6.97 mg/L kaempferol from glucose. To further promote kaempferol production, the acetyl-CoA biosynthetic pathway was overexpressed and p-coumarate was supplied as substrate, which improved kaempferol titer by about 23 and 120%, respectively. Finally, a fed-batch process was developed for better kaempferol fermentation performance, and the production reached 66.29 mg/L in 40 h. The titer of kaempferol in our engineered yeast is 2.5 times of the highest reported titer. Our study provides a possible strategy to produce kaempferol using microbial cell factory.

  17. Engineering Saccharomyces cerevisiae to produce feruloyl esterase for the release of ferulic acid from switchgrass

    USDA-ARS?s Scientific Manuscript database

    The Aspergillus niger ferulic acid esterase gene (faeA) was cloned into Saccharomyces cerevisiae via a yeast expression vector, resulting in efficient expression and secretion of the enzyme in the medium. The recombinant enzyme was purified to homogeneity by anion-exchange and hydrophobic interactio...

  18. Characterization of vacuolar amino acid transporter from Fusarium oxysporum in Saccharomyces cerevisiae.

    PubMed

    Lunprom, Siriporn; Pongcharoen, Pongsanat; Sekito, Takayuki; Kawano-Kawada, Miyuki; Kakinuma, Yoshimi; Akiyama, Koichi

    2015-01-01

    Fusarium oxysporum causes wilt disease in many plant families, and many genes are involved in its development or growth in host plants. A recent study revealed that vacuolar amino acid transporters play an important role in spore formation in Schizosaccharomyces pombe and Saccharomyces cerevisiae. To investigate the role of vacuolar amino acid transporters of this phytopathogenic fungus, the FOXG_11334 (FoAVT3) gene from F. oxysporum was isolated and its function was characterized. Transcription of FoAVT3 was upregulated after rapamycin treatment. A green fluorescent protein fusion of FoAvt3p was localized to vacuolar membranes in both S. cerevisiae and F. oxysporum. Analysis of the amino acid content of the vacuolar fraction and amino acid transport activities using vacuolar membrane vesicles from S. cerevisiae cells heterologously expressing FoAVT3 revealed that FoAvt3p functions as a vacuolar amino acid transporter, exporting neutral amino acids. We conclude that the FoAVT3 gene encodes a vacuolar neutral amino acid transporter.

  19. Truncation of Gal4p explains the inactivation of the GAL/MEL regulon in both Saccharomyces bayanus and some Saccharomyces cerevisiae wine strains.

    PubMed

    Dulermo, Rémi; Legras, Jean-Luc; Brunel, François; Devillers, Hugo; Sarilar, Véronique; Neuvéglise, Cécile; Nguyen, Huu-Vang

    2016-09-01

    In the past, the galactose-negative (Gal(-)) phenotype was a key physiological character used to distinguish Saccharomyces bayanus from S. cerevisiae In this work, we investigated the inactivation of GAL gene networks in S. bayanus, which is an S. uvarum/S. eubayanus hybrid, and in S. cerevisiae wine strains erroneously labelled 'S. bayanus'. We made an inventory of their GAL genes using genomes that were either available publicly, re-sequenced by us, or assembled from public data and completed with targeted sequencing. In the S. eubayanus/S. uvarum CBS 380(T) hybrid, the GAL/MEL network is composed of genes from both parents: from S. uvarum, an otherwise complete set that lacks GAL4, and from S. eubayanus, a truncated version of GAL4 and an additional copy of GAL3 and GAL80 Similarly, two different truncated GAL4 alleles were found in S. cerevisiae wine strains EC1118 and LalvinQA23. The lack of GAL4 activity in these strains was corrected by introducing a full-length copy of S. cerevisiae GAL4 on a CEN4/ARS plasmid. Transformation with this plasmid restored galactose utilisation in Gal(-) strains, and melibiose fermentation in strain CBS 380(T) The melibiose fermentation phenotype, formerly regarded as characteristic of S. uvarum, turned out to be widespread among Saccharomyces species. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. A Minimal Set of Glycolytic Genes Reveals Strong Redundancies in Saccharomyces cerevisiae Central Metabolism

    PubMed Central

    Solis-Escalante, Daniel; Kuijpers, Niels G. A.; Barrajon-Simancas, Nuria; van den Broek, Marcel; Pronk, Jack T.

    2015-01-01

    As a result of ancestral whole-genome and small-scale duplication events, the genomes of Saccharomyces cerevisiae and many eukaryotes still contain a substantial fraction of duplicated genes. In all investigated organisms, metabolic pathways, and more particularly glycolysis, are specifically enriched for functionally redundant paralogs. In ancestors of the Saccharomyces lineage, the duplication of glycolytic genes is purported to have played an important role leading to S. cerevisiae's current lifestyle favoring fermentative metabolism even in the presence of oxygen and characterized by a high glycolytic capacity. In modern S. cerevisiae strains, the 12 glycolytic reactions leading to the biochemical conversion from glucose to ethanol are encoded by 27 paralogs. In order to experimentally explore the physiological role of this genetic redundancy, a yeast strain with a minimal set of 14 paralogs was constructed (the “minimal glycolysis” [MG] strain). Remarkably, a combination of a quantitative systems approach and semiquantitative analysis in a wide array of growth environments revealed the absence of a phenotypic response to the cumulative deletion of 13 glycolytic paralogs. This observation indicates that duplication of glycolytic genes is not a prerequisite for achieving the high glycolytic fluxes and fermentative capacities that are characteristic of S. cerevisiae and essential for many of its industrial applications and argues against gene dosage effects as a means of fixing minor glycolytic paralogs in the yeast genome. The MG strain was carefully designed and constructed to provide a robust prototrophic platform for quantitative studies and has been made available to the scientific community. PMID:26071034

  1. Overexpression of acetyl-CoA synthetase in Saccharomyces cerevisiae increases acetic acid tolerance.

    PubMed

    Ding, Jun; Holzwarth, Garrett; Penner, Michael H; Patton-Vogt, Jana; Bakalinsky, Alan T

    2015-01-01

    Acetic acid-mediated inhibition of the fermentation of lignocellulose-derived sugars impedes development of plant biomass as a source of renewable ethanol. In order to overcome this inhibition, the capacity of Saccharomyces cerevisiae to synthesize acetyl-CoA from acetic acid was increased by overexpressing ACS2 encoding acetyl-coenzyme A synthetase. Overexpression of ACS2 resulted in higher resistance to acetic acid as measured by an increased growth rate and shorter lag phase relative to a wild-type control strain, suggesting that Acs2-mediated consumption of acetic acid during fermentation contributes to acetic acid detoxification. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. Anethole induces apoptotic cell death accompanied by reactive oxygen species production and DNA fragmentation in Aspergillus fumigatus and Saccharomyces cerevisiae.

    PubMed

    Fujita, Ken-Ichi; Tatsumi, Miki; Ogita, Akira; Kubo, Isao; Tanaka, Toshio

    2014-02-01

    trans-Anethole (anethole), a major component of anise oil, has a broad antimicrobial spectrum, and antimicrobial activity that is weaker than that of other antibiotics on the market. When combined with polygodial, nagilactone E, and n-dodecanol, anethole has been shown to possess significant synergistic antifungal activity against a budding yeast, Saccharomyces cerevisiae, and a human opportunistic pathogenic yeast, Candida albicans. However, the antifungal mechanism of anethole has not been completely determined. We found that anethole stimulated cell death of a human opportunistic pathogenic fungus, Aspergillus fumigatus, in addition to S. cerevisiae. The anethole-induced cell death was accompanied by reactive oxygen species production, metacaspase activation, and DNA fragmentation. Several mutants of S. cerevisiae, in which genes related to the apoptosis-initiating execution signals from mitochondria were deleted, were resistant to anethole. These results suggest that anethole-induced cell death could be explained by oxidative stress-dependent apoptosis via typical mitochondrial death cascades in fungi, including A. fumigatus and S. cerevisiae. © 2014 FEBS.

  3. A glycolytic metabolon in Saccharomyces cerevisiae is stabilized by F-actin.

    PubMed

    Araiza-Olivera, Daniela; Chiquete-Felix, Natalia; Rosas-Lemus, Mónica; Sampedro, José G; Peña, Antonio; Mujica, Adela; Uribe-Carvajal, Salvador

    2013-08-01

    In the Saccharomyces cerevisiae glycolytic pathway, 11 enzymes catalyze the stepwise conversion of glucose to two molecules of ethanol plus two CO₂ molecules. In the highly crowded cytoplasm, this pathway would be very inefficient if it were dependent on substrate/enzyme diffusion. Therefore, the existence of a multi-enzymatic glycolytic complex has been suggested. This complex probably uses the cytoskeleton to stabilize the interaction of the various enzymes. Here, the role of filamentous actin (F-actin) in stabilization of a putative glycolytic metabolon is reported. Experiments were performed in isolated enzyme/actin mixtures, cytoplasmic extracts and permeabilized yeast cells. Polymerization of actin was promoted using phalloidin or inhibited using cytochalasin D or latrunculin. The polymeric filamentous F-actin, but not the monomeric globular G-actin, stabilized both the interaction of isolated glycolytic pathway enzyme mixtures and the whole fermentation pathway, leading to higher fermentation activity. The associated complexes were resistant against inhibition as a result of viscosity (promoted by the disaccharide trehalose) or inactivation (using specific enzyme antibodies). In S. cerevisiae, a glycolytic metabolon appear to assemble in association with F-actin. In this complex, fermentation activity is enhanced and enzymes are partially protected against inhibition by trehalose or by antibodies. © 2013 FEBS.

  4. Transposon mutagenesis to improve the growth of recombinant Saccharomyces cerevisiae on D-xylose

    Treesearch

    Haiying Ni; Jose M. Laplaza; Thomas W. Jeffries

    2007-01-01

    Saccharomyces cerevisiae L2612 transformed with genes for xylose reductase and xylitol dehydrogenase (XYL1 and XYL2) grows well on glucose but very poorly on D-xylose. When a gene for D-xylulokinase (XYL3 or XKS1) is overexpressed, growth on glucose is unaffected, but growth on xylose is blocked. Spontaneous or chemically induced mutants of this engineered yeast that...

  5. Genomic Evolution of Saccharomyces cerevisiae under Chinese Rice Wine Fermentation

    PubMed Central

    Li, Yudong; Zhang, Weiping; Zheng, Daoqiong; Zhou, Zhan; Yu, Wenwen; Zhang, Lei; Feng, Lifang; Liang, Xinle; Guan, Wenjun; Zhou, Jingwen; Chen, Jian; Lin, Zhenguo

    2014-01-01

    Rice wine fermentation represents a unique environment for the evolution of the budding yeast, Saccharomyces cerevisiae. To understand how the selection pressure shaped the yeast genome and gene regulation, we determined the genome sequence and transcriptome of a S. cerevisiae strain YHJ7 isolated from Chinese rice wine (Huangjiu), a popular traditional alcoholic beverage in China. By comparing the genome of YHJ7 to the lab strain S288c, a Japanese sake strain K7, and a Chinese industrial bioethanol strain YJSH1, we identified many genomic sequence and structural variations in YHJ7, which are mainly located in subtelomeric regions, suggesting that these regions play an important role in genomic evolution between strains. In addition, our comparative transcriptome analysis between YHJ7 and S288c revealed a set of differentially expressed genes, including those involved in glucose transport (e.g., HXT2, HXT7) and oxidoredutase activity (e.g., AAD10, ADH7). Interestingly, many of these genomic and transcriptional variations are directly or indirectly associated with the adaptation of YHJ7 strain to its specific niches. Our molecular evolution analysis suggested that Japanese sake strains (K7/UC5) were derived from Chinese rice wine strains (YHJ7) at least approximately 2,300 years ago, providing the first molecular evidence elucidating the origin of Japanese sake strains. Our results depict interesting insights regarding the evolution of yeast during rice wine fermentation, and provided a valuable resource for genetic engineering to improve industrial wine-making strains. PMID:25212861

  6. [Molecular evolution of the sulphite efflux gene SSU1 in Saccharomyces cerevisiae].

    PubMed

    Peng, Li-Xin; Sun, Fei-Fei; Huang, Yan-Yan; Li, Zhen-Chong

    2013-11-01

    The SSU1 gene encoding a membrane sulfite pump is a main facilitator invovled in sulfite efflux. In Saccharomyce cerevisiae, various range of resistance to sulfite was observed among strains. To explore the evolution traits of SSU1 gene, the population data of S. cerevisiae were collected and analyzed. The phylogenetic analysis indicated that S. cerevisiae population can be classified into three sub-populations, and the positive selection was detected in population by McDonald-Kreitman test. The anaylsis of Ka/Ks ratios further showed that S. cerevisiae sub-population was undergoing positive selection. This finding was also supported by PAML branch model. Nine potential positive selection sites were predicted by branch-site model, and four sites exclusively belong to the sub-population under positive seletion. The data from ssulp protein structure demonstrated that three sites are substitutions between polar and hydrophobic amino acids, and only one site of substitutaion from basic amino acid to basic amino acid (345R/K). Because amino acid pKa values are crucial for sulfite pump to maintain their routine function, positive selection of these amino acid substitutions might affect sulfite efflux efficient.

  7. Tentacle-type immobilized metal affinity cryogel for invertase purification from Saccharomyces cerevisiae.

    PubMed

    Çetin, Kemal; Perçin, Işık; Denizli, Fatma; Denizli, Adil

    2017-11-01

    The aim of this study is to investigate the usability of cryogel columns for the purification of invertase from Saccharomyces cerevisiae. Poly(2-hydroxyethyl methacrylate) monolithic columns were produced via cryogelation. Ester groups of the poly(2-hydroxyethyl methacrylate) structure were then converted to imine groups by the reaction with poly(ethylene imine) in the presence of NaHCO 3 . Transition metal ions, Cu(II), Co(II), and Ni(II), were chelated on the PEI-modified cryogel columns. Purification of invertase from natural source namely S. cerevisiae was also studied, and the purification fold values were obtained as 41.350, 44.714, and 30.302 for Cu(II)-chelated, Co(II)-chelated, and Ni(II)-chelated PHEMA/PEI columns, respectively.

  8. The mannoprotein of Saccharomyces cerevisiae is an effective bioemulsifier.

    PubMed Central

    Cameron, D R; Cooper, D G; Neufeld, R J

    1988-01-01

    The mannoprotein which is a major component of the cell wall of Saccharomyces cerevisiae is an effective bioemulsifier. Mannoprotein emulsifier was extracted in a high yield from whole cells of fresh bakers' yeast by two methods, by autoclaving in neutral citrate buffer and by digestion with Zymolase (Miles Laboratories; Toronto, Ontario, Canada), a beta-1,3-glucanase. Heat-extracted emulsifier was purified by ultrafiltration and contained approximately 44% carbohydrate (mannose) and 17% protein. Treatment of the emulsifier with protease eliminated emulsification. Kerosene-in-water emulsions were stabilized over a broad range of conditions, from pH 2 to 11, with up to 5% sodium chloride or up to 50% ethanol in the aqueous phase. In the presence of a low concentration of various solutes, emulsions were stable to three cycles of freezing and thawing. An emulsifying agent was extracted from each species or strain of yeast tested, including 13 species of genera other than Saccharomyces. Spent yeast from the manufacture of beer and wine was demonstrated to be a possible source for the large-scale production of this bioemulsifier. PMID:3046488

  9. Antigenic validation of recombinant hemagglutinin-neuraminidase protein of Newcastle disease virus expressed in Saccharomyces cerevisiae.

    PubMed

    Khulape, S A; Maity, H K; Pathak, D C; Mohan, C Madhan; Dey, S

    2015-09-01

    The outer membrane glycoprotein, hemagglutinin-neuraminidase (HN) of Newcastle disease virus (NDV) is important for virus infection and subsequent immune response by host, and offers target for development of recombinant antigen-based immunoassays and subunit vaccines. In this study, the expression of HN protein of NDV is attempted in yeast expression system. Yeast offers eukaryotic environment for protein processing and posttranslational modifications like glycosylation, in addition to higher growth rate and easy genetic manipulation. Saccharomyces cerevisiae was found to be better expression system for HN protein than Pichia pastoris as determined by codon usage analysis. The complete coding  sequence of HN gene was amplified with the histidine tag, cloned in pESC-URA under GAL10 promotor and transformed in Saccharomyces cerevisiae. The recombinant HN (rHN) protein was characterized by western blot, showing glycosylation heterogeneity as observed with other eukaryotic expression systems. The recombinant protein was purified by affinity column purification. The protein could be further used as subunit vaccine.

  10. Ultraviolet mutagenesis studies of [psi], a cytoplasmic determinant of Saccharomyces cerevisiae.

    PubMed

    Tuite, M F; Cox, B S

    1980-07-01

    UV mutagenesis was used to probe the molecular nature of [psi], a nonmitochondrial cytoplasmic determinant of Saccharomyces cerevisiae involved in the control of nonsense suppression. The UV-induced mutation from [psi+] to [psi-] showed characteristics of forward nuclear gene mutation in terms of frequency, induction kinetics, occurrence of whole and sectored mutant clones and the effect of the stage in the growth cycle on mutation frequency. The involvement of pyrimidine dimers in the premutational lesion giving the [psi-] mutation was demonstrated by photoreactivation. UV-induced damage to the [psi] genetic determinant was shown to be repaired by nuclear-coded repair enzymes that are responsible for the repair of nuclear DNA damage. UV-induced damage to mitochondrial DNA appeared to be, at least partly, under the control of different repair processes. The evidence obtained suggests that the [psi] determinant is DNA.

  11. Altering the Rate of Mitosis by Introducing Low-Gigahertz Radiation to Saccharomyces cerevisiae Cells

    NASA Astrophysics Data System (ADS)

    Garg, S.; Ashby, C.

    2017-12-01

    This experiment aims to assess the impact of low-frequency radiation (from common technological tools such as cell phones, scanners, and wifi) on the mitotic rates of cells. In particular, the focus of the study was on the growth and development of Saccharomyces cerevisiae cultures that were exposed to radio waves from a wifi router, which were then compared to a cohort of the same species without exposure. Though routers emit a low gigahertz frequency, they are categorized as Group 2B radiation (possibly carcinogenic) by the International Agency for Research on Cancer of the World Health Organization, signifying that constant exposure poses a potential risk to humans. Twelve agar dishes of active Saccharomyces cerevisiae solution were prepared, with six dishes acting as the control under no added radiation and six acting as the experimental group under 2.4 GHz of radiation due to their proximity to the router. Data on how many cultures proliferated in each dish was collected every three days, with the experiment running for a total of twelve days. All subjects experienced growth curves until day 9 when the experimental group's growth peaked with an average of 62 colonies/dish. Three of the six dishes in this group lost colonies in the following three days, leaving the experimental group with an average of 61 colonies/dish on day 12, while the control group was still increasing by day 12 with an average of 48 colonies/dish, with only one dish undergoing a loss of colonies. Exposing the Saccharomyces cerevisiae cells to low grade radiation resulted in accelerated mitosis, and though the experimental group faced colony death after nine days, the loss was likely due to overpopulation in the dish.

  12. Bioprospecting and evolving alternative xylose and arabinose pathway enzymes for use in Saccharomyces cerevisiae.

    PubMed

    Lee, Sun-Mi; Jellison, Taylor; Alper, Hal S

    2016-03-01

    Bioprospecting is an effective way to find novel enzymes from strains with desirable phenotypes. Such bioprospecting has enabled organisms such as Saccharomyces cerevisiae to utilize nonnative pentose sugars. Yet, the efficiency of this pentose catabolism (especially for the case of arabinose) remains suboptimal. Thus, further pathway optimization or identification of novel, optimal pathways is needed. Previously, we identified a novel set of xylan catabolic pathway enzymes from a superior pentose-utilizing strain of Ustilago bevomyces. These enzymes were used to successfully engineer a xylan-utilizing S. cerevisiae through a blended approach of bioprospecting and evolutionary engineering. Here, we expanded this approach to xylose and arabinose catabolic pathway engineering and demonstrated that bioprospected xylose and arabinose catabolic pathways from U. bevomyces offer alternative choices for enabling efficient pentose catabolism in S. cerevisiae. By introducing a novel set of xylose catabolic genes from U. bevomyces, growth rates were improved up to 85 % over a set of traditional Scheffersomyces stipitis pathway genes. In addition, we suggested an alternative arabinose catabolic pathway which, after directed evolution and pathway engineering, enabled S. cerevisiae to grow on arabinose as a sole carbon source in minimal medium with growth rates upwards of 0.05 h(-1). This pathway represents the most efficient growth of yeast on pure arabinose minimal medium. These pathways provide great starting points for further strain development and demonstrate the utility of bioprospecting from U. bevomyces.

  13. Properties of promoters cloned randomly from the Saccharomyces cerevisiae genome.

    PubMed Central

    Santangelo, G M; Tornow, J; McLaughlin, C S; Moldave, K

    1988-01-01

    Promoters were isolated at random from the genome of Saccharomyces cerevisiae by using a plasmid that contains a divergently arrayed pair of promoterless reporter genes. A comprehensive library was constructed by inserting random (DNase I-generated) fragments into the intergenic region upstream from the reporter genes. Simple in vivo assays for either reporter gene product (alcohol dehydrogenase or beta-galactosidase) allowed the rapid identification of promoters from among these random fragments. Poly(dA-dT) homopolymer tracts were present in three of five randomly cloned promoters. With two exceptions, each RNA start site detected was 40 to 100 base pairs downstream from a TATA element. All of the randomly cloned promoters were capable of activating reporter gene transcription bidirectionally. Interestingly, one of the promoter fragments originated in a region of the S. cerevisiae rDNA spacer; regulated divergent transcription (presumably by RNA polymerase II) initiated in the same region. Images PMID:2847031

  14. Purification and Characterization of Put1p from Saccharomyces cerevisiae

    PubMed Central

    Wanduragala, Srimevan; Sanyal, Nikhilesh; Liang, Xinwen; Becker, Donald F.

    2010-01-01

    In Saccharomyces cerevisiae, the PUT1 and PUT2 genes are required for the conversion of proline to glutamate. The PUT1 gene encodes Put1p, a proline dehydrogenase (PRODH)1 enzyme localized in the mitochondrion. Put1p was expressed and purified from Escherichia coli and shown to have a UV-visible absorption spectrum that is typical of a bound flavin cofactor. A Km value of 36 mM proline and a kcat = 27 s−1 were determined for Put1p using an artificial electron acceptor. Put1p also exhibited high activity using ubiquinone-1 (CoQ1) as an electron acceptor with a kcat = 9.6 s−1 and a Km of 33 µM for CoQ1. In addition, knockout strains of the electron transfer flavoprotein (ETF) homolog in S. cerevisiae were able to grow on proline as the sole nitrogen source demonstrating that ETF is not required for proline utilization in yeast. PMID:20450881

  15. Lycopene overproduction in Saccharomyces cerevisiae through combining pathway engineering with host engineering.

    PubMed

    Chen, Yan; Xiao, Wenhai; Wang, Ying; Liu, Hong; Li, Xia; Yuan, Yingjin

    2016-06-21

    Microbial production of lycopene, a commercially and medically important compound, has received increasing concern in recent years. Saccharomyces cerevisiae is regarded as a safer host for lycopene production than Escherichia coli. However, to date, the lycopene yield (mg/g DCW) in S. cerevisiae was lower than that in E. coli and did not facilitate downstream extraction process, which might be attributed to the incompatibility between host cell and heterologous pathway. Therefore, to achieve lycopene overproduction in S. cerevisiae, both host cell and heterologous pathway should be delicately engineered. In this study, lycopene biosynthesis pathway was constructed by integration of CrtE, CrtB and CrtI in S. cerevisiae CEN.PK2. When YPL062W, a distant genetic locus, was deleted, little acetate was accumulated and approximately 100 % increase in cytosolic acetyl-CoA pool was achieved relative to that in parental strain. Through screening CrtE, CrtB and CrtI from diverse species, an optimal carotenogenic enzyme combination was obtained, and CrtI from Blakeslea trispora (BtCrtI) was found to have excellent performance on lycopene production as well as lycopene proportion in carotenoid. Then, the expression level of BtCrtI was fine-tuned and the effect of cell mating types was also evaluated. Finally, potential distant genetic targets (YJL064W, ROX1, and DOS2) were deleted and a stress-responsive transcription factor INO2 was also up-regulated. Through the above modifications between host cell and carotenogenic pathway, lycopene yield was increased by approximately 22-fold (from 2.43 to 54.63 mg/g DCW). Eventually, in fed-batch fermentation, lycopene production reached 55.56 mg/g DCW, which is the highest reported yield in yeasts. Saccharomyces cerevisiae was engineered to produce lycopene in this study. Through combining host engineering (distant genetic loci and cell mating types) with pathway engineering (enzyme screening and gene fine-tuning), lycopene yield was

  16. Statistics-based model for prediction of chemical biosynthesis yield from Saccharomyces cerevisiae

    PubMed Central

    2011-01-01

    Background The robustness of Saccharomyces cerevisiae in facilitating industrial-scale production of ethanol extends its utilization as a platform to synthesize other metabolites. Metabolic engineering strategies, typically via pathway overexpression and deletion, continue to play a key role for optimizing the conversion efficiency of substrates into the desired products. However, chemical production titer or yield remains difficult to predict based on reaction stoichiometry and mass balance. We sampled a large space of data of chemical production from S. cerevisiae, and developed a statistics-based model to calculate production yield using input variables that represent the number of enzymatic steps in the key biosynthetic pathway of interest, metabolic modifications, cultivation modes, nutrition and oxygen availability. Results Based on the production data of about 40 chemicals produced from S. cerevisiae, metabolic engineering methods, nutrient supplementation, and fermentation conditions described therein, we generated mathematical models with numerical and categorical variables to predict production yield. Statistically, the models showed that: 1. Chemical production from central metabolic precursors decreased exponentially with increasing number of enzymatic steps for biosynthesis (>30% loss of yield per enzymatic step, P-value = 0); 2. Categorical variables of gene overexpression and knockout improved product yield by 2~4 folds (P-value < 0.1); 3. Addition of notable amount of intermediate precursors or nutrients improved product yield by over five folds (P-value < 0.05); 4. Performing the cultivation in a well-controlled bioreactor enhanced the yield of product by three folds (P-value < 0.05); 5. Contribution of oxygen to product yield was not statistically significant. Yield calculations for various chemicals using the linear model were in fairly good agreement with the experimental values. The model generally underestimated the ethanol production as

  17. The genetic architecture of low-temperature adaptation in the wine yeast Saccharomyces cerevisiae.

    PubMed

    García-Ríos, Estéfani; Morard, Miguel; Parts, Leopold; Liti, Gianni; Guillamón, José M

    2017-02-14

    Low-temperature growth and fermentation of wine yeast can enhance wine aroma and make them highly desirable traits for the industry. Elucidating response to cold in Saccharomyces cerevisiae is, therefore, of paramount importance to select or genetically improve new wine strains. As most enological traits of industrial importance in yeasts, adaptation to low temperature is a polygenic trait regulated by many interacting loci. In order to unravel the genetic determinants of low-temperature fermentation, we mapped quantitative trait loci (QTLs) by bulk segregant analyses in the F13 offspring of two Saccharomyces cerevisiae industrial strains with divergent performance at low temperature. We detected four genomic regions involved in the adaptation at low temperature, three of them located in the subtelomeric regions (chromosomes XIII, XV and XVI) and one in the chromosome XIV. The QTL analysis revealed that subtelomeric regions play a key role in defining individual variation, which emphasizes the importance of these regions' adaptive nature. The reciprocal hemizygosity analysis (RHA), run to validate the genes involved in low-temperature fermentation, showed that genetic variation in mitochondrial proteins, maintenance of correct asymmetry and distribution of phospholipid in the plasma membrane are key determinants of low-temperature adaptation.

  18. Metabolomic Comparison of Saccharomyces cerevisiae and the Cryotolerant Species S. bayanus var. uvarum and S. kudriavzevii during Wine Fermentation at Low Temperature

    PubMed Central

    López-Malo, María; Querol, Amparo; Guillamon, José Manuel

    2013-01-01

    Temperature is one of the most important parameters affecting the length and rate of alcoholic fermentation and final wine quality. Wine produced at low temperature is often considered to have improved sensory qualities. However, there are certain drawbacks to low temperature fermentations such as reduced growth rate, long lag phase, and sluggish or stuck fermentations. To investigate the effects of temperature on commercial wine yeast, we compared its metabolome growing at 12°C and 28°C in a synthetic must. Some species of the Saccharomyces genus have shown better adaptation at low temperature than Saccharomyces cerevisiae. This is the case of the cryotolerant yeasts Saccharomyces bayanus var. uvarum and Saccharomyces kudriavzevii. In an attempt to detect inter-specific metabolic differences, we characterized the metabolome of these species growing at 12°C, which we compared with the metabolome of S. cerevisiae (not well adapted at low temperature) at the same temperature. Our results show that the main differences between the metabolic profiling of S. cerevisiae growing at 12°C and 28°C were observed in lipid metabolism and redox homeostasis. Moreover, the global metabolic comparison among the three species revealed that the main differences between the two cryotolerant species and S. cerevisiae were in carbohydrate metabolism, mainly fructose metabolism. However, these two species have developed different strategies for cold resistance. S. bayanus var. uvarum presented elevated shikimate pathway activity, while S. kudriavzevii displayed increased NAD+ synthesis. PMID:23527304

  19. Schizosaccharomyces pombe and Saccharomyces cerevisiae yeasts in sequential fermentations: Effect on phenolic acids of fermented Kei-apple (Dovyalis caffra L.) juice.

    PubMed

    Minnaar, P P; Jolly, N P; Paulsen, V; Du Plessis, H W; Van Der Rijst, M

    2017-09-18

    Kei-apple (Dovyalis caffra) is an evergreen tree indigenous to Southern Africa. The fruit contains high concentrations of l-malic acid, ascorbic acid, and phenolic acids. Kei-apple juice was sequentially inoculated with Schizosaccharomyces pombe and Saccharomyces cerevisiae yeasts. A reference fermentation using only S. cerevisiae was included. The fermentation was monitored by recording mass loss. At the end of fermentation, twelve untrained judges conducted free choice aroma profiling on the fruit wines. The Kei-apple juice and wines were analysed for total titratable acidity, total soluble solids, pH, alcohol, l-malic acid, and phenolic acids. Total titratable acidity was ca. 70% lower in Kei-apple wines produced with S. pombe+S. cerevisiae than in Kei-apple juice. Kei-apple wines produced with S. pombe+S. cerevisiae showed substantially lower concentrations of l-malic acid than Kei-apple wines produced with S. cerevisiae only. Wines produced with S. cerevisiae only proved higher in phenolic acid concentrations than wines produced with S. pombe+S. cerevisiae. Chlorogenic acid was the most abundant phenolic acid measured in the Kei-apple wines, followed by protocatechuic acid. Judges described the Kei-apple wines produced with S. pombe+S. cerevisiae as having noticeable off-odours, while wines produced with S. cerevisiae were described as fresh and fruity. Kei-apple wines (S. pombe+S. cerevisiae and S. cerevisiae) were of comparable vegetative and organic character. Saccharomyces cerevisiae produced Kei-apple wine with increased caffeic, chlorogenic, protocatechuic, and sinapic acids, whereas S. pombe+S. cerevisiae produced Kei-apple wines with increased ferulic, and p-coumaric acids and low l-malic acid. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Biogeographical characterization of Saccharomyces cerevisiae wine yeast by molecular methods

    PubMed Central

    Tofalo, Rosanna; Perpetuini, Giorgia; Schirone, Maria; Fasoli, Giuseppe; Aguzzi, Irene; Corsetti, Aldo; Suzzi, Giovanna

    2013-01-01

    Biogeography is the descriptive and explanatory study of spatial patterns and processes involved in the distribution of biodiversity. Without biogeography, it would be difficult to study the diversity of microorganisms because there would be no way to visualize patterns in variation. Saccharomyces cerevisiae, “the wine yeast,” is the most important species involved in alcoholic fermentation, and in vineyard ecosystems, it follows the principle of “everything is everywhere.” Agricultural practices such as farming (organic versus conventional) and floor management systems have selected different populations within this species that are phylogenetically distinct. In fact, recent ecological and geographic studies highlighted that unique strains are associated with particular grape varieties in specific geographical locations. These studies also highlighted that significant diversity and regional character, or ‘terroir,’ have been introduced into the winemaking process via this association. This diversity of wild strains preserves typicity, the high quality, and the unique flavor of wines. Recently, different molecular methods were developed to study population dynamics of S. cerevisiae strains in both vineyards and wineries. In this review, we will provide an update on the current molecular methods used to reveal the geographical distribution of S. cerevisiae wine yeast. PMID:23805132

  1. Expression of Pneumocystis jirovecii Major Surface Glycoprotein in Saccharomyces cerevisiae

    PubMed Central

    Kutty, Geetha; England, Katherine J.; Kovacs, Joseph A.

    2013-01-01

    The major surface glycoprotein (Msg), which is the most abundant protein expressed on the cell surface of Pneumocystis organisms, plays an important role in the attachment of this organism to epithelial cells and macrophages. In the present study, we expressed Pneumocystis jirovecii Msg in Saccharomyces cerevisiae, a phylogenetically related organism. Full-length P. jirovecii Msg was expressed with a DNA construct that used codons optimized for expression in yeast. Unlike in Pneumocystis organisms, recombinant Msg localized to the plasma membrane of yeast rather than to the cell wall. Msg expression was targeted to the yeast cell wall by replacing its signal peptide, serine-threonine–rich region, and glycophosphatidylinositol anchor signal region with the signal peptide of cell wall protein α-agglutinin of S. cerevisiae, the serine-threonine–rich region of epithelial adhesin (Epa1) of Candida glabrata, and the carboxyl region of the cell wall protein (Cwp2) of S. cerevisiae, respectively. Immunofluorescence analysis and treatment with β-1,3 glucanase demonstrated that the expressed Msg fusion protein localized to the yeast cell wall. Surface expression of Msg protein resulted in increased adherence of yeast to A549 alveolar epithelial cells. Heterologous expression of Msg in yeast will facilitate studies of the biologic properties of Pneumocystis Msg. PMID:23532098

  2. Factors affecting the palmitoyl-coenzyme A desaturase of Saccharomyces cerevisiae

    NASA Technical Reports Server (NTRS)

    Klein, H. P.; Volkmann, C. M.

    1975-01-01

    The activity and stability of the palmitoyl-coenzyme A (CoA) desaturase complex of Saccharomyces cerevisiae was influenced by several factors. Cells, grown nonaerobically and then incubated with glucose, either in air or under N2, showed a marked increase in desaturase activity. Cycloheximide, added during such incubations, prevented the increase in activity, suggesting de novo synthesis. The stability of the desaturase from cells grown nonaerobically was affected by subsequent treatment of the cells; enzyme from freshly harvested cells, or from cells that were then shaken under nitrogen, readily lost activity upon washing or during density gradient analysis, whereas aerated cells, in the presence or absence of glucose, yielded stable enzyme preparations. The loss of activity in nonaerobic preparations could be reversed by adding soluble supernatant from these homogenates and could be prevented by growing the cells in the presence of palmitoleic acid and ergosterol, but not with several other lipids tested.

  3. Mutations in Ran system affected telomere silencing in Saccharomyces cerevisiae

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

    Hayashi, Naoyuki; Department of Molecular Oncology, Cancer Research Institute, Kanazawa University, Kanazawa, Ishikawa 920-0934; Kobayashi, Masahiko

    The Ran GTPase system regulates the direction and timing of several cellular events, such as nuclear-cytosolic transport, centrosome formation, and nuclear envelope assembly in telophase. To gain insight into the Ran system's involvement in chromatin formation, we investigated gene silencing at the telomere in several mutants of the budding yeast Saccharomyces cerevisiae, which had defects in genes involved in the Ran system. A mutation of the RanGAP gene, rna1-1, caused reduced silencing at the telomere, and partial disruption of the nuclear Ran binding factor, yrb2-{delta}2, increased this silencing. The reduced telomere silencing in rna1-1 cells was suppressed by a highmore » dosage of the SIR3 gene or the SIT4 gene. Furthermore, hyperphosphorylated Sir3 protein accumulated in the rna1-1 mutant. These results suggest that RanGAP is required for the heterochromatin structure at the telomere in budding yeast.« less

  4. MLH1 mutations differentially affect meiotic functions in Saccharomyces cerevisiae.

    PubMed Central

    Hoffmann, Eva R; Shcherbakova, Polina V; Kunkel, Thomas A; Borts, Rhona H

    2003-01-01

    To test whether missense mutations in the cancer susceptibility gene MLH1 adversely affect meiosis, we examined 14 yeast MLH1 mutations for effects on meiotic DNA transactions and gamete viability in the yeast Saccharomyces cerevisiae. Mutations analogous to those associated with hereditary nonpolyposis colorectal cancer (HNPCC) or those that reduce Mlh1p interactions with ATP or DNA all impair replicative mismatch repair as measured by increased mutation rates. However, their effects on meiotic heteroduplex repair, crossing over, chromosome segregation, and gametogenesis vary from complete loss of meiotic functions to no meiotic defect, and mutants defective in one meiotic process are not necessarily defective in others. DNA binding and ATP binding but not ATP hydrolysis are required for meiotic crossing over. The results reveal clear separation of different Mlh1p functions in mitosis and meiosis, and they suggest that some, but not all, MLH1 mutations may be a source of human infertility. PMID:12618391

  5. Force Sensitivity in Saccharomyces cerevisiae Flocculins.

    PubMed

    Chan, Cho X J; El-Kirat-Chatel, Sofiane; Joseph, Ivor G; Jackson, Desmond N; Ramsook, Caleen B; Dufrêne, Yves F; Lipke, Peter N

    2016-01-01

    Many fungal adhesins have short, β-aggregation-prone sequences that play important functional roles, and in the Candida albicans adhesin Als5p, these sequences cluster the adhesins after exposure to shear force. Here, we report that Saccharomyces cerevisiae flocculins Flo11p and Flo1p have similar β-aggregation-prone sequences and are similarly stimulated by shear force, despite being nonhomologous. Shear from vortex mixing induced the formation of small flocs in cells expressing either adhesin. After the addition of Ca(2+), yeast cells from vortex-sheared populations showed greatly enhanced flocculation and displayed more pronounced thioflavin-bright surface nanodomains. At high concentrations, amyloidophilic dyes inhibited Flo1p- and Flo11p-mediated agar invasion and the shear-induced increase in flocculation. Consistent with these results, atomic force microscopy of Flo11p showed successive force-distance peaks characteristic of sequentially unfolding tandem repeat domains, like Flo1p and Als5p. Flo11p-expressing cells bound together through homophilic interactions with adhesion forces of up to 700 pN and rupture lengths of up to 600 nm. These results are consistent with the potentiation of yeast flocculation by shear-induced formation of high-avidity domains of clustered adhesins at the cell surface, similar to the activation of Candida albicans adhesin Als5p. Thus, yeast adhesins from three independent gene families use similar force-dependent interactions to drive cell adhesion. IMPORTANCE The Saccharomyces cerevisiae flocculins mediate the formation of cellular aggregates and biofilm-like mats, useful in clearing yeast from fermentations. An important property of fungal adhesion proteins, including flocculins, is the ability to form catch bonds, i.e., bonds that strengthen under tension. This strengthening is based, at least in part, on increased avidity of binding due to clustering of adhesins in cell surface nanodomains. This clustering depends on

  6. Exploring the Saccharomyces cerevisiae Volatile Metabolome: Indigenous versus Commercial Strains

    PubMed Central

    Alves, Zélia; Melo, André; Figueiredo, Ana Raquel; Coimbra, Manuel A.; Gomes, Ana C.; Rocha, Sílvia M.

    2015-01-01

    Winemaking is a highly industrialized process and a number of commercial Saccharomyces cerevisiae strains are used around the world, neglecting the diversity of native yeast strains that are responsible for the production of wines peculiar flavours. The aim of this study was to in-depth establish the S. cerevisiae volatile metabolome and to assess inter-strains variability. To fulfill this objective, two indigenous strains (BT2652 and BT2453 isolated from spontaneous fermentation of grapes collected in Bairrada Appellation, Portugal) and two commercial strains (CSc1 and CSc2) S. cerevisiae were analysed using a methodology based on advanced multidimensional gas chromatography (HS-SPME/GC×GC-ToFMS) tandem with multivariate analysis. A total of 257 volatile metabolites were identified, distributed over the chemical families of acetals, acids, alcohols, aldehydes, ketones, terpenic compounds, esters, ethers, furan-type compounds, hydrocarbons, pyrans, pyrazines and S-compounds. Some of these families are related with metabolic pathways of amino acid, carbohydrate and fatty acid metabolism as well as mono and sesquiterpenic biosynthesis. Principal Component Analysis (PCA) was used with a dataset comprising all variables (257 volatile components), and a distinction was observed between commercial and indigenous strains, which suggests inter-strains variability. In a second step, a subset containing esters and terpenic compounds (C10 and C15), metabolites of particular relevance to wine aroma, was also analysed using PCA. The terpenic and ester profiles express the strains variability and their potential contribution to the wine aromas, specially the BT2453, which produced the higher terpenic content. This research contributes to understand the metabolic diversity of indigenous wine microflora versus commercial strains and achieved knowledge that may be further exploited to produce wines with peculiar aroma properties. PMID:26600152

  7. Yeast ratio is a critical factor for sequential fermentation of papaya wine by Williopsis saturnus and Saccharomyces cerevisiae

    PubMed Central

    Lee, Pin-Rou; Kho, Stephanie Hui Chern; Yu, Bin; Curran, Philip; Liu, Shao-Quan

    2013-01-01

    Summary The growth kinetics and fermentation performance of Williopsis saturnus and Saccharomyces cerevisiae at ratios of 10:1, 1:1 and 1:10 (W.:S.) were studied in papaya juice with initial 7-day fermentation by W. saturnus, followed by S. cerevisiae. The growth kinetics of W. saturnus were similar at all ratios, but its maximum cell count decreased as the proportion of S. cerevisiae was increased. Conversely, there was an early death of S. cerevisiae at the ratio of 10:1. Williopsis saturnus was the dominant yeast at 10:1 ratio that produced papaya wine with elevated concentrations of acetate esters. On the other hand, 1:1 and 1:10 ratios allowed the coexistence of both yeasts which enabled the flavour-enhancing potential of W. saturnus as well as the ethyl ester and alcohol-producing abilities of S. cerevisiae. In particular, 1:1 and 1:10 ratios resulted in production of more ethyl esters, alcohols and 2-phenylethyl acetate. However, the persistence of both yeasts at 1:1 and 1:10 ratios led to formation of high levels of acetic acid. The findings suggest that yeast ratio is a critical factor for sequential fermentation of papaya wine by W. saturnus and S. cerevisiae as a strategy to modulate papaya wine flavour. PMID:23171032

  8. Yeast ratio is a critical factor for sequential fermentation of papaya wine by Williopsis saturnus and Saccharomyces cerevisiae.

    PubMed

    Lee, Pin-Rou; Kho, Stephanie Hui Chern; Yu, Bin; Curran, Philip; Liu, Shao-Quan

    2013-07-01

    The growth kinetics and fermentation performance of Williopsis saturnus and Saccharomyces cerevisiae at ratios of 10:1, 1:1 and 1:10 (W.:S.) were studied in papaya juice with initial 7-day fermentation by W.saturnus, followed by S. cerevisiae. The growth kinetics of W. saturnus were similar at all ratios, but its maximum cell count decreased as the proportion of S. cerevisiae was increased. Conversely, there was an early death of S. cerevisiae at the ratio of 10:1. Williopsis saturnus was the dominant yeast at 10:1 ratio that produced papaya wine with elevated concentrations of acetate esters. On the other hand, 1:1 and 1:10 ratios allowed the coexistence of both yeasts which enabled the flavour-enhancing potential of W.saturnus as well as the ethyl ester and alcohol-producing abilities of S. cerevisiae. In particular, 1:1 and 1:10 ratios resulted in production of more ethyl esters, alcohols and 2-phenylethyl acetate. However, the persistence of both yeasts at 1:1 and 1:10 ratios led to formation of high levels of acetic acid. The findings suggest that yeast ratio is a critical factor for sequential fermentation of papaya wine by W.saturnus and S. cerevisiae as a strategy to modulate papaya wine flavour. © 2012 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  9. Rmt1 catalyzes zinc-finger independent arginine methylation of ribosomal protein Rps2 in Saccharomyces cerevisiae

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

    Lipson, Rebecca S.; Webb, Kristofor J.; Clarke, Steven G., E-mail: clarke@mbi.ucla.edu

    2010-01-22

    Rps2/rpS2 is a well conserved protein of the eukaryotic ribosomal small subunit. Rps2 has previously been shown to contain asymmetric dimethylarginine residues, the addition of which is catalyzed by zinc-finger-containing arginine methyltransferase 3 (Rmt3) in the fission yeast Schizosaccharomyces pombe and protein arginine methyltransferase 3 (PRMT3) in mammalian cells. Here, we demonstrate that despite the lack of a zinc-finger-containing homolog of Rmt3/PRMT3 in the budding yeast Saccharomyces cerevisiae, Rps2 is partially modified to generate asymmetric dimethylarginine and monomethylarginine residues. We find that this modification of Rps2 is dependent upon the major arginine methyltransferase 1 (Rmt1) in S. cerevisiae. These resultsmore » are suggestive of a role for Rmt1 in modifying the function of Rps2 in a manner distinct from that occurring in S. pombe and mammalian cells.« less

  10. Maltotriose fermentation by Saccharomyces cerevisiae.

    PubMed

    Zastrow, C R; Hollatz, C; de Araujo, P S; Stambuk, B U

    2001-07-01

    Maltotriose, the second most abundant sugar of brewer's wort, is not fermented but is respired by several industrial yeast strains. We have isolated a strain capable of growing on a medium containing maltotriose and the respiratory inhibitor, antimycin A. This strain produced equivalent amounts of ethanol from 20 g l(-1) glucose, maltose, or maltotriose. We performed a detailed analysis of the rates of active transport and intracellular hydrolysis of maltotriose by this strain, and by a strain that does not ferment this sugar. The kinetics of sugar hydrolysis by both strains was similar, and our results also indicated that yeast cells do not synthesize a maltotriose-specific alpha-glucosidase. However, when considering active sugar transport, a different pattern was observed. The maltotriose-fermenting strain showed the same rate of active maltose or maltotriose transport, while the strain that could not ferment maltotriose showed a lower rate of maltotriose transport when compared with the rates of active maltose transport. Thus, our results revealed that transport across the plasma membrane, and not intracellular hydrolysis, is the rate-limiting step for the fermentation of maltotriose by these Saccharomyces cerevisiae cells.

  11. Mating-type switching by chromosomal inversion in methylotrophic yeasts suggests an origin for the three-locus Saccharomyces cerevisiae system

    PubMed Central

    Hanson, Sara J.; Byrne, Kevin P.; Wolfe, Kenneth H.

    2014-01-01

    Saccharomyces cerevisiae has a complex system for switching the mating type of haploid cells, requiring the genome to have three mating-type (MAT)–like loci and a mechanism for silencing two of them. How this system originated is unknown, because the three-locus system is present throughout the family Saccharomycetaceae, whereas species in the sister Candida clade have only one locus and do not switch. Here we show that yeasts in a third clade, the methylotrophs, have a simpler two-locus switching system based on reversible inversion of a section of chromosome with MATa genes at one end and MATalpha genes at the other end. In Hansenula polymorpha the 19-kb invertible region lies beside a centromere so that, depending on the orientation, either MATa or MATalpha is silenced by centromeric chromatin. In Pichia pastoris, the orientation of a 138-kb invertible region puts either MATa or MATalpha beside a telomere and represses transcription of MATa2 or MATalpha2. Both species are homothallic, and inversion of their MAT regions can be induced by crossing two strains of the same mating type. The three-locus system of S. cerevisiae, which uses a nonconservative mechanism to replace DNA at MAT, likely evolved from a conservative two-locus system that swapped genes between expression and nonexpression sites by inversion. The increasing complexity of the switching apparatus, with three loci, donor bias, and cell lineage tracking, can be explained by continuous selection to increase sporulation ability in young colonies. Our results provide an evolutionary context for the diversity of switching and silencing mechanisms. PMID:25349420

  12. Mating-type switching by chromosomal inversion in methylotrophic yeasts suggests an origin for the three-locus Saccharomyces cerevisiae system.

    PubMed

    Hanson, Sara J; Byrne, Kevin P; Wolfe, Kenneth H

    2014-11-11

    Saccharomyces cerevisiae has a complex system for switching the mating type of haploid cells, requiring the genome to have three mating-type (MAT)-like loci and a mechanism for silencing two of them. How this system originated is unknown, because the three-locus system is present throughout the family Saccharomycetaceae, whereas species in the sister Candida clade have only one locus and do not switch. Here we show that yeasts in a third clade, the methylotrophs, have a simpler two-locus switching system based on reversible inversion of a section of chromosome with MATa genes at one end and MATalpha genes at the other end. In Hansenula polymorpha the 19-kb invertible region lies beside a centromere so that, depending on the orientation, either MATa or MATalpha is silenced by centromeric chromatin. In Pichia pastoris, the orientation of a 138-kb invertible region puts either MATa or MATalpha beside a telomere and represses transcription of MATa2 or MATalpha2. Both species are homothallic, and inversion of their MAT regions can be induced by crossing two strains of the same mating type. The three-locus system of S. cerevisiae, which uses a nonconservative mechanism to replace DNA at MAT, likely evolved from a conservative two-locus system that swapped genes between expression and nonexpression sites by inversion. The increasing complexity of the switching apparatus, with three loci, donor bias, and cell lineage tracking, can be explained by continuous selection to increase sporulation ability in young colonies. Our results provide an evolutionary context for the diversity of switching and silencing mechanisms.

  13. Bioethanol strains of Saccharomyces cerevisiae characterised by microsatellite and stress resistance.

    PubMed

    Reis, Vanda Renata; Antonangelo, Ana Teresa Burlamaqui Faraco; Bassi, Ana Paula Guarnieri; Colombi, Débora; Ceccato-Antonini, Sandra Regina

    Strains of Saccharomyces cerevisiae may display characteristics that are typical of rough-type colonies, made up of cells clustered in pseudohyphal structures and comprised of daughter buds that do not separate from the mother cell post-mitosis. These strains are known to occur frequently in fermentation tanks with significant lower ethanol yield when compared to fermentations carried out by smooth strains of S. cerevisiae that are composed of dispersed cells. In an attempt to delineate genetic and phenotypic differences underlying the two phenotypes, this study analysed 10 microsatellite loci of 22 S. cerevisiae strains as well as stress resistance towards high concentrations of ethanol and glucose, low pH and cell sedimentation rates. The results obtained from the phenotypic tests by Principal-Component Analysis revealed that unlike the smooth colonies, the rough colonies of S. cerevisiae exhibit an enhanced resistance to stressful conditions resulting from the presence of excessive glucose and ethanol and high sedimentation rate. The microsatellite analysis was not successful to distinguish between the colony phenotypes as phenotypic assays. The relevant industrial strain PE-2 was observed in close genetic proximity to rough-colony although it does not display this colony morphology. A unique genetic pattern specific to a particular phenotype remains elusive. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  14. Engineered Saccharomyces cerevisiae strain for improved xylose utilization with a three-plasmid SUMO yeast expression system

    USDA-ARS?s Scientific Manuscript database

    A three-plasmid yeast expression system utilizing the portable small ubiquitin-like modifier (SUMO) vector set combined with the efficient endogenous yeast protease Ulp1 was developed for production of large amounts of soluble functional protein in Saccharomyces cerevisiae. Each vector has a differ...

  15. Draft Genome Sequence of Saccharomyces cerevisiae Barra Grande (BG-1), a Brazilian Industrial Bioethanol-Producing Strain

    PubMed Central

    Coutouné, Natalia; Mulato, Aline Tieppo Nogueira

    2017-01-01

    ABSTRACT Here, we present the draft genome sequence of Saccharomyces cerevisiae BG-1, a Brazilian industrial strain widely used for bioethanol production from sugarcane. The 11.7-Mb genome sequence consists of 216 scaffolds and harbors 5,607 predicted protein-coding genes. PMID:28360170

  16. Invasive Saccharomyces cerevisiae in a liver transplant patient: case report and review of infection in transplant recipients.

    PubMed

    Popiel, K Y; Wong, P; Lee, M J; Langelier, M; Sheppard, D C; Vinh, D C

    2015-06-01

    Saccharomyces cerevisiae, an ascosporogenous yeast commonly used in the production of food, is an emerging infection in immunocompromised patients. We report the case of a 60-year-old man whose orthotopic liver transplant was complicated by S. cerevisiae fungemia and peritoneal abscess, successfully treated with caspofungin and drainage. We also review the literature of invasive saccharomycoses in recipients of hematologic and solid organ transplants. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Saccharomyces cerevisiae KNU5377 stress response during high-temperature ethanol fermentation.

    PubMed

    Kim, Il-Sup; Kim, Young-Saeng; Kim, Hyun; Jin, Ingnyol; Yoon, Ho-Sung

    2013-03-01

    Fuel ethanol production is far more costly to produce than fossil fuels. There are a number of approaches to cost-effective fuel ethanol production from biomass. We characterized stress response of thermotolerant Saccharomyces cerevisiae KNU5377 during glucose-based batch fermentation at high temperature (40°C). S. cerevisiae KNU5377 (KNU5377) transcription factors (Hsf1, Msn2/4, and Yap1), metabolic enzymes (hexokinase, glyceraldehyde-3-phosphate dehydrogenase, glucose-6-phosphate dehydrogenase, isocitrate dehydrogenase, and alcohol dehydrogenase), antioxidant enzymes (thioredoxin 3, thioredoxin reductase, and porin), and molecular chaperones and its cofactors (Hsp104, Hsp82, Hsp60, Hsp42, Hsp30, Hsp26, Cpr1, Sti1, and Zpr1) are upregulated during fermentation, in comparison to S. cerevisiae S288C (S288C). Expression of glyceraldehyde-3-phosphate dehydrogenase increased significantly in KNU5377 cells. In addition, cellular hydroperoxide and protein oxidation, particularly lipid peroxidation of triosephosphate isomerase, was lower in KNU5377 than in S288C. Thus, KNU5377 activates various cell rescue proteins through transcription activators, improving tolerance and increasing alcohol yield by rapidly responding to fermentation stress through redox homeostasis and proteostasis.

  18. The Response to Heat Shock and Oxidative Stress in Saccharomyces cerevisiae

    PubMed Central

    Morano, Kevin A.; Grant, Chris M.; Moye-Rowley, W. Scott

    2012-01-01

    A common need for microbial cells is the ability to respond to potentially toxic environmental insults. Here we review the progress in understanding the response of the yeast Saccharomyces cerevisiae to two important environmental stresses: heat shock and oxidative stress. Both of these stresses are fundamental challenges that microbes of all types will experience. The study of these environmental stress responses in S. cerevisiae has illuminated many of the features now viewed as central to our understanding of eukaryotic cell biology. Transcriptional activation plays an important role in driving the multifaceted reaction to elevated temperature and levels of reactive oxygen species. Advances provided by the development of whole genome analyses have led to an appreciation of the global reorganization of gene expression and its integration between different stress regimens. While the precise nature of the signal eliciting the heat shock response remains elusive, recent progress in the understanding of induction of the oxidative stress response is summarized here. Although these stress conditions represent ancient challenges to S. cerevisiae and other microbes, much remains to be learned about the mechanisms dedicated to dealing with these environmental parameters. PMID:22209905

  19. A dynamic flux balance model and bottleneck identification of glucose, xylose, xylulose co-fermentation in Saccharomyces cerevisiae

    USDA-ARS?s Scientific Manuscript database

    Economically viable production of lignocellulosic ethanol requires efficient conversion of feedstock sugars to ethanol. Saccharomyces cerevisiae cannot ferment xylose, the main five-carbon sugars in biomass, but can ferment xylulose, an enzymatically derived isomer. Xylulose fermentation is slow rel...

  20. Bread, beer and wine: Saccharomyces cerevisiae diversity reflects human history.

    PubMed

    Legras, Jean-Luc; Merdinoglu, Didier; Cornuet, Jean-Marie; Karst, Francis

    2007-05-01

    Fermented beverages and foods have played a significant role in most societies worldwide for millennia. To better understand how the yeast species Saccharomyces cerevisiae, the main fermenting agent, evolved along this historical and expansion process, we analysed the genetic diversity among 651 strains from 56 different geographical origins, worldwide. Their genotyping at 12 microsatellite loci revealed 575 distinct genotypes organized in subgroups of yeast types, i.e. bread, beer, wine, sake. Some of these groups presented unexpected relatedness: Bread strains displayed a combination of alleles intermediate between beer and wine strains, and strains used for rice wine and sake were most closely related to beer and bread strains. However, up to 28% of genetic diversity between these technological groups was associated with geographical differences which suggests local domestications. Focusing on wine yeasts, a group of Lebanese strains were basal in an F(ST) tree, suggesting a Mesopotamia-based origin of most wine strains. In Europe, migration of wine strains occurred through the Danube Valley, and around the Mediterranean Sea. An approximate Bayesian computation approach suggested a postglacial divergence (most probable period 10,000-12,000 bp). As our results suggest intimate association between man and wine yeast across centuries, we hypothesize that yeast followed man and vine migrations as a commensal member of grapevine flora.

  1. A new biological test of water toxicity-yeast Saccharomyces cerevisiae conductometric test.

    PubMed

    Dolezalova, Jaroslava; Rumlova, Lubomira

    2014-11-01

    This new biological test of water toxicity is based on monitoring of specific conductivity changes of yeast Saccharomyces cerevisiae suspension as a result of yeast fermentation activity inhibition in toxic conditions. The test was verified on ten substances with various mechanisms of toxic effect and the results were compared with two standard toxicity tests based on Daphnia magna mobility inhibition (EN ISO 6341) and Vibrio fischeri bioluminescence inhibition (EN ISO 11348-2) and with the results of the S. cerevisiae lethal test (Rumlova and Dolezalova, 2012). The new biological test - S. cerevisiae conductometric test - is an express method developed primarily for field conditions. It is applicable in case of need of immediate information about water toxicity. Fast completion is an advantage of this test (time necessary for test completion is about 60min), the test is simple and the test organism - dried instant yeast - belongs among its biggest advantages because of its long-term storage life and broad availability. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Glycerol positive promoters for tailored metabolic engineering of the yeast Saccharomyces cerevisiae.

    PubMed

    Ho, Ping-Wei; Klein, Mathias; Futschik, Matthias; Nevoigt, Elke

    2018-05-01

    Glycerol offers several advantages as a substrate for biotechnological applications. An important step toward using the popular production host Saccharomyces cerevisiae for glycerol-based bioprocesses has been the fact that in recent studies commonly used S. cerevisiae strains were engineered to grow in synthetic medium containing glycerol as the sole carbon source. For metabolic engineering projects of S. cerevisiae growing on glycerol, characterized promoters are missing. In the current study, we used transcriptome analysis and a yECitrine-based fluorescence reporter assay to select and characterize 25 useful promoters. The promoters of the genes ALD4 and ADH2 showed 4.2-fold and 3-fold higher activities compared to the well-known strong TEF1 promoter. Moreover, the collection contains promoters with graded activities in synthetic glycerol medium and different degrees of glucose repression. To demonstrate the general applicability of the promoter collection, we successfully used a subset of the characterized promoters with graded activities in order to optimize growth on glycerol in an engineered derivative of CEN.PK, in which glycerol catabolism exclusively occurs via a non-native DHA pathway.

  3. Chromium (VI) biosorption by Saccharomyces cerevisiae subjected to chemical and thermal treatments.

    PubMed

    De Rossi, Andrea; Rigon, Magali Rejane; Zaparoli, Munise; Braido, Rafael Dalmas; Colla, Luciane Maria; Dotto, Guilherme Luiz; Piccin, Jeferson Steffanello

    2018-05-28

    The potential of chemically and thermally treated Saccharomyces cerevisiae as biosorbents for chromium (VI) was investigated in this work. The presence of this toxic metal in industrial effluents is harmful to the environment, so, it is important to develop environmental friendly methods for Cr(VI) removal from these effluents. Biosorption using microorganisms such as S. cerevisiae is a viable treatment option because this biomass is easily available as a residue of fermentation industries. In this study, the affecting variables on Cr(VI) biosorption were studied by constructing biosorption isotherms, using lyophilized yeast subjected to chemical and thermal treatments. S. cerevisiae was able to remove 99.66% of Cr(VI) from effluents by biosorption. The significant variables affecting biosorption were pH, initial Cr(VI) concentration, and contact time. The biosorption isotherms were represented by the Freundlich model for the untreated biomass, BET model for the chemically treated biomass, and Langmuir model for the heat-treated biomass. Thermal treatment increased the biosorption affinity of the biomass for chromium, while the chemical treatment facilitated the formation of a multilayer.

  4. Acquisition of thermotolerant yeast Saccharomyces cerevisiae by breeding via stepwise adaptation.

    PubMed

    Satomura, Atsushi; Katsuyama, Yoshiaki; Miura, Natsuko; Kuroda, Kouichi; Tomio, Ayako; Bamba, Takeshi; Fukusaki, Eiichiro; Ueda, Mitsuyoshi

    2013-01-01

    A thermotolerant Saccharomyces cerevisiae yeast strain, YK60-1, was bred from a parental strain, MT8-1, via stepwise adaptation. YK60-1 grew at 40°C, a temperature at which MT8-1 could not grow at all. YK60-1 exhibited faster growth than MT8-1 at 30°C. To investigate the mechanisms how MT8-1 acquired thermotolerance, DNA microarray analysis was performed. The analysis revealed the induction of stress-responsive genes such as those encoding heat shock proteins and trehalose biosynthetic enzymes in YK60-1. Furthermore, nontargeting metabolome analysis showed that YK60-1 accumulated more trehalose, a metabolite that contributes to stress tolerance in yeast, than MT8-1. In conclusion, S. cerevisiae MT8-1 acquired thermotolerance by induction of specific stress-responsive genes and enhanced intracellular trehalose levels. © 2013 American Institute of Chemical Engineers.

  5. Transformation of Saccharomyces cerevisiae and Schizosaccharomyces pombe with linear plasmids containing 2 micron sequences.

    PubMed Central

    Guerrini, A M; Ascenzioni, F; Tribioli, C; Donini, P

    1985-01-01

    Linear plasmids were constructed by adding telomeres prepared from Tetrahymena pyriformis rDNA to a circular hybrid Escherichia coli-yeast vector and transforming Saccharomyces cerevisiae. The parental vector contained the entire 2 mu yeast circle and the LEU gene from S. cerevisiae. Three transformed clones were shown to contain linear plasmids which were characterized by restriction analysis and shown to be rearranged versions of the desired linear plasmids. The plasmids obtained were imperfect palindromes: part of the parental vector was present in duplicated form, part as unique sequences and part was absent. The sequences that had been lost included a large portion of the 2 mu circle. The telomeres were approximately 450 bp longer than those of T. pyriformis. DNA prepared from transformed S. cerevisiae clones was used to transform Schizosaccharomyces pombe. The transformed S. pombe clones contained linear plasmids identical in structure to their linear parents in S. cerevisiae. No structural re-arrangements or integration into S. pombe was observed. Little or no telomere growth had occurred after transfer from S. cerevisiae to S. pombe. A model is proposed to explain the genesis of the plasmids. Images Fig. 1. Fig. 2. Fig. 4. PMID:3896773

  6. Genomic Sequence of Saccharomyces cerevisiae BAW-6, a Yeast Strain Optimal for Brewing Barley Shochu

    PubMed Central

    Mori, Kazuki; Tashiro, Kosuke; Higuchi, Yujiro; Takashita, Hideharu

    2018-01-01

    ABSTRACT Here, we report the draft genome sequence of Saccharomyces cerevisiae strain BAW-6, which is used for the production of barley shochu, a traditional Japanese spirit. This genomic information can be used to elucidate the genetic basis underlying the high alcohol production capacity and citric acid tolerance of shochu yeast. PMID:29622617

  7. Torulaspora delbrueckii contribution in mixed brewing fermentations with different Saccharomyces cerevisiae strains.

    PubMed

    Canonico, Laura; Comitini, Francesca; Ciani, Maurizio

    2017-10-16

    In recent years, there has been growing demand for distinctive high quality beer. Fermentation management has a fundamental role in beer quality and the levels of aroma compounds. Use of non-conventional yeast has been proposed to enhance beer bioflavor. In the present work we investigated mixed fermentations using three commercial Saccharomyces cerevisiae strains, without and with addition of a selected Torulaspora delbrueckii strain evaluating their interactions, as well as the aroma profiles. At the S. cerevisiae/T. delbrueckii co-inoculation ratio of 1:20, viable cell counts indicated that T. delbrueckii dominated all of the three combinations. In the mixed fermentations, T. delbrueckii provided higher levels of higher alcohols (excepting of β-phenyl ethanol), in contrast to data obtained in winemaking, where higher alcohols had lower levels. Moreover, mixed fermentations showed significantly higher ethyl acetate (from 5 to 16mg/L) and isoamyl acetate (from 0.019 to 0.128mg/L), and were generally lower in ethyl hexanoate and ethyl octanoate. Therefore, irrespective of S. cerevisiae strain, T. delbrueckii influenced on all mixed fermentations. On the other hand, the mixed fermentations were also affected by each of the three S. cerevisiae strains, which resulted in beers with distinctive flavors. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Genomic evolution of Saccharomyces cerevisiae under Chinese rice wine fermentation.

    PubMed

    Li, Yudong; Zhang, Weiping; Zheng, Daoqiong; Zhou, Zhan; Yu, Wenwen; Zhang, Lei; Feng, Lifang; Liang, Xinle; Guan, Wenjun; Zhou, Jingwen; Chen, Jian; Lin, Zhenguo

    2014-09-10

    Rice wine fermentation represents a unique environment for the evolution of the budding yeast, Saccharomyces cerevisiae. To understand how the selection pressure shaped the yeast genome and gene regulation, we determined the genome sequence and transcriptome of a S. cerevisiae strain YHJ7 isolated from Chinese rice wine (Huangjiu), a popular traditional alcoholic beverage in China. By comparing the genome of YHJ7 to the lab strain S288c, a Japanese sake strain K7, and a Chinese industrial bioethanol strain YJSH1, we identified many genomic sequence and structural variations in YHJ7, which are mainly located in subtelomeric regions, suggesting that these regions play an important role in genomic evolution between strains. In addition, our comparative transcriptome analysis between YHJ7 and S288c revealed a set of differentially expressed genes, including those involved in glucose transport (e.g., HXT2, HXT7) and oxidoredutase activity (e.g., AAD10, ADH7). Interestingly, many of these genomic and transcriptional variations are directly or indirectly associated with the adaptation of YHJ7 strain to its specific niches. Our molecular evolution analysis suggested that Japanese sake strains (K7/UC5) were derived from Chinese rice wine strains (YHJ7) at least approximately 2,300 years ago, providing the first molecular evidence elucidating the origin of Japanese sake strains. Our results depict interesting insights regarding the evolution of yeast during rice wine fermentation, and provided a valuable resource for genetic engineering to improve industrial wine-making strains. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  9. Genetic effects of methyl benzimidazole-2-yl-carbamate on Saccharomyces cerevisiae.

    PubMed Central

    Wood, J S

    1982-01-01

    The genetic effects of the mitotic inhibitor methyl benzimidazole-2-yl-carbamate (MBC) have been studied in Saccharomyces cerevisiae. MBC had little or no effect on the frequency of mutation. In some experiments MBC caused an increase in the frequency of mitotic recombination; however, this effect was small and not reproducible. The primary genetic effect of MBC was to induce mitotic chromosome loss at a high frequency. Chromosome loss occurred at equal frequencies for all chromosomes tested (13 of 16). Cells which had lost multiple chromosomes were found more frequently than predicted if individual chromosome loss events were independent. The probability of loss for a particular chromosome increased with length of time cells were incubated with MBC. MBC treatment also increased the frequency at which polyploid cells were found. These results suggested that MBC acted to disrupt the structure or function of the mitotic spindle and cause chromosome nondisjunction. PMID:6757720

  10. Stereochemistry of Furfural Reduction by a Saccharomyces cerevisiae Aldehyde Reductase That Contributes to In Situ Furfural Detoxification

    USDA-ARS?s Scientific Manuscript database

    Ari1p from Saccharomyces cerevisiae, recently identified as an intermediate subclass short-chain dehydrogenase/reductase, contributes in situ to the detoxification of furfural. Furfural inhibits efficient ethanol production by the yeast, particularly when the carbon source is acid-treated lignocell...

  11. DISRUPTION OF THE SACCHAROMYCES CEREVISIAE GENE FOR NADPH-CYTOCHROME P450-REDUCTASE CAUSES INCREASED SENSITIVITY TO KETOCONAZOLE

    EPA Science Inventory

    Strains of Saccharomyces cerevisiae deleted in the NADPH-cytochrome P450 reductase gene by transplacement are 200-fold more sensitive to ketoconazole, an inhibitor of the cytochrome P450 lanosterol 14-demethylase. Resistance is restored through complementation by the plasmid-born...

  12. 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.

  13. Mechanism and Regulation of Protein Synthesis in Saccharomyces cerevisiae

    PubMed Central

    Dever, Thomas E.; Kinzy, Terri Goss; Pavitt, Graham D.

    2016-01-01

    In this review, we provide an overview of protein synthesis in the yeast Saccharomyces cerevisiae. The mechanism of protein synthesis is well conserved between yeast and other eukaryotes, and molecular genetic studies in budding yeast have provided critical insights into the fundamental process of translation as well as its regulation. The review focuses on the initiation and elongation phases of protein synthesis with descriptions of the roles of translation initiation and elongation factors that assist the ribosome in binding the messenger RNA (mRNA), selecting the start codon, and synthesizing the polypeptide. We also examine mechanisms of translational control highlighting the mRNA cap-binding proteins and the regulation of GCN4 and CPA1 mRNAs. PMID:27183566

  14. Advancing Metabolic Engineering of Saccharomyces cerevisiae Using the CRISPR/Cas System

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

    Lian, Jiazhang; HamediRad, Mohammad; Zhao, Huimin

    Thanks to its ease of use, modularity, and scalability, the clustered regularly interspaced short palindromic repeats (CRISPR) system has been increasingly used in the design and engineering of Saccharomyces cerevisiae, one of the most popular hosts for industrial biotechnology. This review summarizes the recent development of this disruptive technology for metabolic engineering applications, including CRISPR-mediated gene knock-out and knock-in as well as transcriptional activation and interference. More importantly, multi-functional CRISPR systems that combine both gain- and loss-of-function modulations for combinatorial metabolic engineering are highlighted.

  15. Advancing Metabolic Engineering of Saccharomyces cerevisiae Using the CRISPR/Cas System

    DOE PAGES

    Lian, Jiazhang; HamediRad, Mohammad; Zhao, Huimin

    2018-04-18

    Thanks to its ease of use, modularity, and scalability, the clustered regularly interspaced short palindromic repeats (CRISPR) system has been increasingly used in the design and engineering of Saccharomyces cerevisiae, one of the most popular hosts for industrial biotechnology. This review summarizes the recent development of this disruptive technology for metabolic engineering applications, including CRISPR-mediated gene knock-out and knock-in as well as transcriptional activation and interference. More importantly, multi-functional CRISPR systems that combine both gain- and loss-of-function modulations for combinatorial metabolic engineering are highlighted.

  16. Looking for immunotolerance: a case of allergy to baker's yeast (Saccharomyces cerevisiae).

    PubMed

    Pajno, G B; Passalacqua, G; Salpietro, C; Vita, D; Caminiti, L; Barberio, G

    2005-09-01

    We describe one case of baker's yeast true allergy in a boy with previously diagnosed mite-allergy and atopic dermatitis. At the age of 6, being atopic dermatitis and rhinitis well controlled by drugs, he began to experience generalized urticaria and asthma after eating pizza and bread, but only fresh from the oven. The diagnostic workup revealed single sensitization to baker's yeast (Saccharomyces cerevisiae), and a severe systemic reaction also occurred during the prick-by-prick procedure. After discussing with parents, no special dietary restriction was suggested but the use of autoinjectable adrenaline and on demand salbutamol. A diary of symptoms was recorded by means of a visual-analog scale. During the subsequent 2 years, the severity of symptoms was progressively reduced, and presently urticaria has disappeared. Only cough persists, invariantly after eating just-baked and yeast-containing foods. If bread, pizza and cakes are ate more than one hour after preparation, no symptom occur at all. Baker's yeast is a common component of everyday diet and it usually acts as an allergen only by the inhalatory route. We speculate that the continuous exposure to saccharomyces in foods may have lead to an immunotolerance with a progressive reduction of symptoms, whereas why the allergens is active only in ready-baked foods remains unexplained.

  17. Effect of nagilactone E on cell morphology and glucan biosynthesis in budding yeast Saccharomyces cerevisiae.

    PubMed

    Hayashi, Kengo; Yamaguchi, Yoshihiro; Ogita, Akira; Tanaka, Toshio; Kubo, Isao; Fujita, Ken-Ichi

    2018-05-14

    Nagilactones are norditerpene dilactones isolated from the root bark of Podocarpus nagi. Although nagilactone E has been reported to show antifungal activities, its activity is weaker than that of antifungals on the market. Nagilactone E enhances the antifungal activity of phenylpropanoids such as anethole and isosafrole against nonpathogenic Saccharomyces cerevisiae and pathogenic Candida albicans. However, the detailed mechanisms underlying the antifungal activity of nagilactone E itself have not yet been elucidated. Therefore, we investigated the antifungal mechanisms of nagilactone E using S. cerevisiae. Although nagilactone E induced lethality in vegetatively growing cells, it did not affect cell viability in non-growing cells. Nagilactone E-induced morphological changes in the cells, such as inhomogeneous thickness of the glucan layer and leakage of cytoplasm. Furthermore, a dose-dependent decrease in the amount of newly synthesized (1, 3)-β-glucan was detected in the membrane fractions of the yeast incubated with nagilactone E. These results suggest that nagilactone E exhibits an antifungal activity against S. cerevisiae by depending on cell wall fragility via the inhibition of (1, 3)-β-glucan biosynthesis. Additionally, we confirmed nagilactone E-induced morphological changes of a human pathogenic fungus Aspergillus fumigatus. Therefore, nagilactone E is a potential antifungal drug candidate with fewer adverse effects. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Central roles of iron in the regulation of oxidative stress in the yeast Saccharomyces cerevisiae.

    PubMed

    Matsuo, Ryo; Mizobuchi, Shogo; Nakashima, Maya; Miki, Kensuke; Ayusawa, Dai; Fujii, Michihiko

    2017-10-01

    Oxygen is essential for aerobic organisms but causes cytotoxicity probably through the generation of reactive oxygen species (ROS). In this study, we screened for the genes that regulate oxidative stress in the yeast Saccharomyces cerevisiae, and found that expression of CTH2/TIS11 caused an increased resistance to ROS. CTH2 is up-regulated upon iron starvation and functions to remodel metabolism to adapt to iron starvation. We showed here that increased resistance to ROS by CTH2 would likely be caused by the decreased ROS production due to the decreased activity of mitochondrial respiration, which observation is consistent with the fact that CTH2 down-regulates the mitochondrial respiratory proteins. We also found that expression of CTH1, a paralog of CTH2, also caused an increased resistance to ROS. This finding supported the above view, because mitochondrial respiratory proteins are the common targets of CTH1 and CTH2. We further showed that supplementation of iron in medium augmented the growth of S. cerevisiae under oxidative stress, and expression of CTH2 and supplementation of iron collectively enhanced its growth under oxidative stress. Since CTH2 is regulated by iron, these findings suggested that iron played crucial roles in the regulation of oxidative stress in S. cerevisiae.

  19. Production of pyruvate from mannitol by mannitol-assimilating pyruvate decarboxylase-negative Saccharomyces cerevisiae.

    PubMed

    Yoshida, Shiori; Tanaka, Hideki; Hirayama, Makoto; Murata, Kousaku; Kawai, Shigeyuki

    2015-01-01

    Mannitol is contained in brown macroalgae up to 33% (w/w, dry weight), and thus is a promising carbon source for white biotechnology. However, Saccharomyces cerevisiae, a key cell factory, is generally regarded to be unable to assimilate mannitol for growth. We have recently succeeded in producing S. cerevisiae that can assimilate mannitol through spontaneous mutations of Tup1-Cyc8, each of which constitutes a general corepressor complex. In this study, we demonstrate production of pyruvate from mannitol using this mannitol-assimilating S. cerevisiae through deletions of all 3 pyruvate decarboxylase genes. The resultant mannitol-assimilating pyruvate decarboxylase-negative strain produced 0.86 g/L pyruvate without use of acetate after cultivation for 4 days, with an overall yield of 0.77 g of pyruvate per g of mannitol (the theoretical yield was 79%). Although acetate was not needed for growth of this strain in mannitol-containing medium, addition of acetate had a significant beneficial effect on production of pyruvate. This is the first report of production of a valuable compound (other than ethanol) from mannitol using S. cerevisiae, and is an initial platform from which the productivity of pyruvate from mannitol can be improved.

  20. Expression of a Dianthus flavonoid glucosyltransferase in Saccharomyces cerevisiae for whole-cell biocatalysis.

    PubMed

    Werner, Sean R; Morgan, John A

    2009-07-15

    Glycosyltransferases are promising biocatalysts for the synthesis of small molecule glycosides. In this study, Saccharomyces cerevisiae expressing a flavonoid glucosyltransferase (GT) from Dianthus caryophyllus (carnation) was investigated as a whole-cell biocatalyst. Two yeast expression systems were compared using the flavonoid naringenin as a model substrate. Under in vitro conditions, naringenin-7-O-glucoside was formed and a higher specific glucosyl transfer activity was found using a galactose inducible expression system compared to a constitutive expression system. However, S. cerevisiae expressing the GT constitutively was significantly more productive than the galactose inducible system under in vivo conditions. Interestingly, the glycosides were recovered directly from the culture broth and did not accumulate intracellularly. A previously uncharacterized naringenin glycoside formed using the D. caryophyllus GT was identified as naringenin-4'-O-glucoside. It was found that S. cerevisiae cells hydrolyze naringenin-7-O-glucoside during whole-cell biocatalysis, resulting in a low final glycoside titer. When phloretin was added as a substrate to the yeast strain expressing the GT constitutively, the natural product phlorizin was formed. This study demonstrates S. cerevisiae is a promising whole-cell biocatalyst host for the production of valuable glycosides.

  1. Effect of Domestication on the Spread of the [PIN+] Prion in Saccharomyces cerevisiae

    PubMed Central

    Kelly, Amy C.; Busby, Ben; Wickner, Reed B.

    2014-01-01

    Prions (infectious proteins) cause fatal neurodegenerative diseases in mammals. In the yeast Saccharomyces cerevisiae, many toxic and lethal variants of the [PSI+] and [URE3] prions have been identified in laboratory strains, although some commonly studied variants do not seem to impair cell growth. Phylogenetic analysis has revealed four major clades of S. cerevisiae that share histories of two prion proteins and largely correspond to different ecological niches of yeast. The [PIN+] prion was most prevalent in commercialized niches, infrequent among wine/vineyard strains, and not observed in ancestral isolates. As previously reported, the [PSI+] and [URE3] prions are not found in any of these strains. Patterns of heterozygosity revealed genetic mosaicism and indicated extensive outcrossing among divergent strains in commercialized environments. In contrast, ancestral isolates were all homozygous and wine/vineyard strains were closely related to each other and largely homozygous. Cellular growth patterns were highly variable within and among clades, although ancestral isolates were the most efficient sporulators and domesticated strains showed greater tendencies for flocculation. [PIN+]-infected strains had a significantly higher likelihood of polyploidy, showed a higher propensity for flocculation compared to uninfected strains, and had higher sporulation efficiencies compared to domesticated, uninfected strains. Extensive phenotypic variability among strains from different environments suggests that S. cerevisiae is a niche generalist and that most wild strains are able to switch from asexual to sexual and from unicellular to multicellular growth in response to environmental conditions. Our data suggest that outbreeding and multicellular growth patterns adapted for domesticated environments are ecological risk factors for the [PIN+] prion in wild yeast. PMID:24812307

  2. Evidence for Avt6 as a vacuolar exporter of acidic amino acids in Saccharomyces cerevisiae cells.

    PubMed

    Chahomchuen, Thippayarat; Hondo, Kana; Ohsaki, Mariko; Sekito, Takayuki; Kakinuma, Yoshimi

    2009-12-01

    Here we examined the significance of Avt6, a vacuolar exporter of glutamate and aspartate suggested by the in vitro membrane vesicle experiment, in vacuolar compartmentalization of amino acids in Saccharomyces cerevisiae cells. Fluorescent microscopic observation of GFP-fused Avt6 revealed it to be exclusively localized to the vacuolar membrane, with the amount of Myc-tagged Avt6 significantly increased under nitrogen starvation. Glutamate uptake by cells was enhanced by deletion of the AVT6 gene, indicating indirect involvement of Avt6 in cellular glutamate accumulation. Differences in acidic amino acid content of both total and vacuolar fractions were insignificant between the parent and avt6Delta cells when cultured in nutrient-rich conditions. However, in nitrogen-starved conditions, the amount of glutamate and aspartate in the vacuolar fraction was notably increased in the avt6Delta cells. Avt6 is thus involved in vacuolar amino acid compartmentalization in S. cerevisiae cells, especially under conditions of nitrogen starvation.

  3. Effects of aeration on formation and localization of the acetyl coenzyme A synthetases of Saccharomyces cerevisiae

    NASA Technical Reports Server (NTRS)

    Klein, H. P.; Jahnke, L.

    1979-01-01

    Previous studies on the yeast Saccharomyces cerevisiae have shown that two different forms of the enzyme acetyl coenzyme A synthetase (ACS) are present, depending on the conditions under which the cells are grown. The paper evaluates the usefulness of a method designed to assay both synthetases simultaneously in yeast homogenates. The data presented confirm the possibility of simultaneous detection and estimation of the amount of both ACSs of S. cerevisiae in crude homogenates of this strain, making possible the study of physiological factors involved in the formation of these isoenzymes. One important factor for specifying which of the two enzymes is found in these yeast cells is the presence or absence of oxygen in their environment. Aeration not only affects the ratio of the two ACSs but also appears to affect the cellular distribution of these enzymes. Most of the data presented suggest the possibility that the nonaerobic ACS may serve as a precursor to the aerobic form.

  4. Efficient ethanol production from beetle-killed lodgepole pine using SPORL technology and Saccharomyces cerevisiae without detoxification

    Treesearch

    Junyong Zhu; Xiaolin Luo; Shen Tian; Roland Gleisner; Jose Negron; Eric Horn

    2011-01-01

    This study applied Sulfite Pretreatment to Overcome Recalcitrance of Lignocelluloses (SPORL) to evaluate the potential of mountain pine beetle-killed lodgepole pine for ethanol production using conventional Saccharomyces cerevisiae without hydrolysate detoxification. The results indicate that the beetle-killed trees are more susceptible to SPORL pretreatment than live...

  5. RNAseq-based transcriptome comparison of Saccharomyces cerevisiae strains isolated from diverse fermentative environments.

    PubMed

    Ibáñez, Clara; Pérez-Torrado, Roberto; Morard, Miguel; Toft, Christina; Barrio, Eladio; Querol, Amparo

    2017-09-18

    Transcriptome analyses play a central role in unraveling the complexity of gene expression regulation in Saccharomyces cerevisiae. This species, one of the most important microorganisms for humans given its industrial applications, shows an astonishing degree of genetic and phenotypic variability among different strains adapted to specific environments. In order to gain novel insights into the Saccharomyces cerevisiae biology of strains adapted to different fermentative environments, we analyzed the whole transcriptome of three strains isolated from wine, flor wine or mezcal fermentations. An RNA-seq transcriptome comparison of the different yeasts in the samples obtained during synthetic must fermentation highlighted the differences observed in the genes that encode mannoproteins, and in those involved in aroma, sugar transport, glycerol and alcohol metabolism, which are important under alcoholic fermentation conditions. These differences were also observed in the physiology of the strains after mannoprotein and aroma determinations. This study offers an essential foundation for understanding how gene expression variations contribute to the fermentation differences of the strains adapted to unequal fermentative environments. Such knowledge is crucial to make improvements in fermentation processes and to define targets for the genetic improvement or selection of wine yeasts. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Raw starch conversion by Saccharomyces cerevisiae expressing Aspergillus tubingensis amylases

    PubMed Central

    2013-01-01

    Background Starch is one of the most abundant organic polysaccharides available for the production of bio-ethanol as an alternative transport fuel. Cost-effective utilisation of starch requires consolidated bioprocessing (CBP) where a single microorganism can produce the enzymes required for hydrolysis of starch, and also convert the glucose monomers to ethanol. Results The Aspergillus tubingensis T8.4 α-amylase (amyA) and glucoamylase (glaA) genes were cloned and expressed in the laboratory strain Saccharomyces cerevisiae Y294 and the semi-industrial strain, S. cerevisiae Mnuα1. The recombinant AmyA and GlaA displayed protein sizes of 110–150 kDa and 90 kDa, respectively, suggesting significant glycosylation in S. cerevisiae. The Mnuα1[AmyA-GlaA] and Y294[AmyA-GlaA] strains were able to utilise 20 g l-1 raw corn starch as sole carbohydrate source, with ethanol titers of 9.03 and 6.67 g l-1 (0.038 and 0.028 g l-1 h-1), respectively, after 10 days. With a substrate load of 200 g l-1 raw corn starch, Mnuα1[AmyA-GlaA] yielded 70.07 g l-1 ethanol (0.58 g l-1 h-1) after 120 h of fermentation, whereas Y294[AmyA-GlaA] was less efficient at 43.33 g l-1 ethanol (0.36 g l-1 h-1). Conclusions In a semi-industrial amylolytic S. cerevisiae strain expressing the A. tubingensis α-amylase and glucoamylase genes, 200 g l-1 raw starch was completely hydrolysed (saccharified) in 120 hours with 74% converted to released sugars plus fermentation products and the remainder presumably to biomass. The single-step conversion of raw starch represents significant progress towards the realisation of CBP without the need for any heat pretreatment. Furthermore, the amylases were produced and secreted by the host strain, thus circumventing the need for exogenous amylases. PMID:24286270

  7. Raw starch conversion by Saccharomyces cerevisiae expressing Aspergillus tubingensis amylases.

    PubMed

    Viktor, Marko J; Rose, Shaunita H; van Zyl, Willem H; Viljoen-Bloom, Marinda

    2013-11-29

    Starch is one of the most abundant organic polysaccharides available for the production of bio-ethanol as an alternative transport fuel. Cost-effective utilisation of starch requires consolidated bioprocessing (CBP) where a single microorganism can produce the enzymes required for hydrolysis of starch, and also convert the glucose monomers to ethanol. The Aspergillus tubingensis T8.4 α-amylase (amyA) and glucoamylase (glaA) genes were cloned and expressed in the laboratory strain Saccharomyces cerevisiae Y294 and the semi-industrial strain, S. cerevisiae Mnuα1. The recombinant AmyA and GlaA displayed protein sizes of 110-150 kDa and 90 kDa, respectively, suggesting significant glycosylation in S. cerevisiae. The Mnuα1[AmyA-GlaA] and Y294[AmyA-GlaA] strains were able to utilise 20 g l-1 raw corn starch as sole carbohydrate source, with ethanol titers of 9.03 and 6.67 g l-1 (0.038 and 0.028 g l-1 h-1), respectively, after 10 days. With a substrate load of 200 g l-1 raw corn starch, Mnuα1[AmyA-GlaA] yielded 70.07 g l-1 ethanol (0.58 g l-1 h-1) after 120 h of fermentation, whereas Y294[AmyA-GlaA] was less efficient at 43.33 g l-1 ethanol (0.36 g l-1 h-1). In a semi-industrial amylolytic S. cerevisiae strain expressing the A. tubingensis α-amylase and glucoamylase genes, 200 g l-1 raw starch was completely hydrolysed (saccharified) in 120 hours with 74% converted to released sugars plus fermentation products and the remainder presumably to biomass. The single-step conversion of raw starch represents significant progress towards the realisation of CBP without the need for any heat pretreatment. Furthermore, the amylases were produced and secreted by the host strain, thus circumventing the need for exogenous amylases.

  8. Hybridization and Polyploidization of Saccharomyces cerevisiae Strains by Transformation-Associated Cell Fusion

    PubMed Central

    Takagi, Atsuko; Harashima, Satoshi; Oshima, Yasuji

    1985-01-01

    Hybrid or polyploid clones of Saccharomyces cerevisiae produced by protoplast fusion were easily isolated by selecting transformants with the plasmid phenotype because the transformation was directly associated with cell fusion. When haploid cells were used as the original strain, the transformants were mostly diploids with a significant fraction of polyploids (triploids or tetraploids). Repeated transformation after curing the plasmid gave rise to clones with higher ploidy, but the frequency of cell fusion was severely reduced as ploidy increased. Images PMID:16346702

  9. Transformations of inorganic mercury by Candida albicans and Saccharomyces cerevisiae

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

    Yannai, S.; Berdicevsky, I.; Duek, L.

    1991-01-01

    Saccharomyces cerevisiae and Candida albicans were incubated with 0.25, 0.5, or 0.75 {mu}g of Hg (as HgCl{sub 2}) per ml of Nelson's medium in the presence of trace amounts of oxygen at 28{degree}C for 12 days. Two control media were used, one without added Hg and one without yeast inoculum. Yeast cell growth was estimated after 1, 2, 3, and 8 days of incubation. The contents of organomercury in the system and of elemental mercury released from the media and collected in traps were determined at the end of the experiments. The results were as follows: (1) C. albicans wasmore » the more mercury-resistant species, but both yeast species failed to grown in the media containing 0.75 {mu}g of Hg per ml.; (2) The amounts of organomercury produced by the two species were proportional to the amount of HgCl{sub 2} added to the medium. In all cases C. albicans produced considerably larger amounts of methylmercury than S. cerevisiae; (3) The amounts of elemental Hg produced were inversely proportional to the HgCl{sub 2} level added in the case of S. cerevisiae but were all similar in the case of C. albicans;and (4) Neither organomercury nor elemental Hg was produced in any of the control media.« less

  10. Genomic Sequence of Saccharomyces cerevisiae BAW-6, a Yeast Strain Optimal for Brewing Barley Shochu.

    PubMed

    Kajiwara, Yasuhiro; Mori, Kazuki; Tashiro, Kosuke; Higuchi, Yujiro; Takegawa, Kaoru; Takashita, Hideharu

    2018-04-05

    Here, we report the draft genome sequence of Saccharomyces cerevisiae strain BAW-6, which is used for the production of barley shochu, a traditional Japanese spirit. This genomic information can be used to elucidate the genetic basis underlying the high alcohol production capacity and citric acid tolerance of shochu yeast. Copyright © 2018 Kajiwara et al.

  11. From Saccharomyces cerevisiae to human: The important gene co-expression modules.

    PubMed

    Liu, Wei; Li, Li; Ye, Hua; Chen, Haiwei; Shen, Weibiao; Zhong, Yuexian; Tian, Tian; He, Huaqin

    2017-08-01

    Network-based systems biology has become an important method for analyzing high-throughput gene expression data and gene function mining. Yeast has long been a popular model organism for biomedical research. In the current study, a weighted gene co-expression network analysis algorithm was applied to construct a gene co-expression network in Saccharomyces cerevisiae . Seventeen stable gene co-expression modules were detected from 2,814 S. cerevisiae microarray data. Further characterization of these modules with the Database for Annotation, Visualization and Integrated Discovery tool indicated that these modules were associated with certain biological processes, such as heat response, cell cycle, translational regulation, mitochondrion oxidative phosphorylation, amino acid metabolism and autophagy. Hub genes were also screened by intra-modular connectivity. Finally, the module conservation was evaluated in a human disease microarray dataset. Functional modules were identified in budding yeast, some of which are associated with patient survival. The current study provided a paradigm for single cell microorganisms and potentially other organisms.

  12. Electron microscopy for ultrastructural analysis and protein localization in Saccharomyces cerevisiae

    PubMed Central

    Frankl, Andri; Mari, Muriel; Reggiori, Fulvio

    2015-01-01

    The yeast Saccharomyces cerevisiae is a key model system for studying of a multitude of cellular processes because of its amenability to genetics, molecular biology and biochemical procedures. Ultrastructural examinations of this organism, though, are traditionally difficult because of the presence of a thick cell wall and the high density of cytoplasmic proteins. A series of recent methodological and technical developments, however, has revived interest in morphological analyses of yeast (e.g. 123). Here we present a review of established and new methods, from sample preparation to imaging, for the ultrastructural analysis of S. cerevisiae. We include information for the use of different fixation methods, embedding procedures, approaches for contrast enhancement, and sample visualization techniques, with references to successful examples. The goal of this review is to guide researchers that want to investigate a particular process at the ultrastructural level in yeast by aiding in the selection of the most appropriate approach to visualize a specific structure or subcellular compartment. PMID:28357267

  13. Enhanced pathway efficiency of Saccharomyces cerevisiae by introducing thermo-tolerant devices.

    PubMed

    Liu, Yueqin; Zhang, Genli; Sun, Huan; Sun, Xiangying; Jiang, Nisi; Rasool, Aamir; Lin, Zhanglin; Li, Chun

    2014-10-01

    In this study, thermo-tolerant devices consisting of heat shock genes from thermophiles were designed and introduced into Saccharomyces cerevisiae for improving its thermo-tolerance. Among ten engineered thermo-tolerant yeasts, T.te-TTE2469, T.te-GroS2 and T.te-IbpA displayed over 25% increased cell density and 1.5-4-fold cell viability compared with the control. Physiological characteristics of thermo-tolerant strains revealed that better cell wall integrity, higher trehalose content and enhanced metabolic energy were preserved by thermo-tolerant devices. Engineered thermo-tolerant strain was used to investigate the impact of thermo-tolerant device on pathway efficiency by introducing β-amyrin synthesis pathway, showed 28.1% increased β-amyrin titer, 28-35°C broadened growth temperature range and 72h shortened fermentation period. The results indicated that implanting heat shock proteins from thermophiles to S. cerevisiae would be an efficient approach to improve its thermo-tolerance. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Saccharomyces cerevisiae Produces a Yeast Substance that Exhibits Estrogenic Activity in Mammalian Systems

    NASA Astrophysics Data System (ADS)

    Feldman, David; Stathis, Peter A.; Hirst, Margaret A.; Price Stover, E.; Do, Yung S.; Kurz, Walter

    1984-06-01

    Partially purified lipid extracts of Saccharomyces cerevisiae contain a substance that displaces tritiated estradiol from rat uterine cytosol estrogen receptors. The yeast product induces estrogenic bioresponses in mammalian systems as measured by induction of progesterone receptors in cultured MCF-7 human breast cancer cells and by a uterotrophic response and progesterone receptor induction after administration to ovariectomized mice. The findings raise the possibility that bakers' yeast may be a source of environmental estrogens.

  15. Microbial Cells as Biosorbents for Heavy Metals: Accumulation of Uranium by Saccharomyces cerevisiae and Pseudomonas aeruginosa

    PubMed Central

    Strandberg, Gerald W.; Shumate, Starling E.; Parrott, John R.

    1981-01-01

    Uranium accumulated extracellularly on the surfaces of Saccharomyces cerevisiae cells. The rate and extent of accumulation were subject to environmental parameters, such as pH, temperature, and interference by certain anions and cations. Uranium accumulation by Pseudomonas aeruginosa occurred intracellularly and was extremely rapid (<10 s), and no response to environmental parameters could be detected. Metabolism was not required for metal uptake by either organism. Cell-bound uranium reached a concentration of 10 to 15% of the dry cell weight, but only 32% of the S. cerevisiae cells and 44% of the P. aeruginosa cells within a given population possessed visible uranium deposits when examined by electron microscopy. Rates of uranium uptake by S. cerevisiae were increased by chemical pretreatment of the cells. Uranium could be removed chemically from S. cerevisiae cells, and the cells could then be reused as a biosorbent. Images PMID:16345691

  16. ATP-dependent export of neutral amino acids by vacuolar membrane vesicles of Saccharomyces cerevisiae.

    PubMed

    Ishimoto, Masaya; Sugimoto, Naoko; Sekito, Takayuki; Kawano-Kawada, Miyuki; Kakinuma, Yoshimi

    2012-01-01

    Amino acid analysis of Saccharomyces cerevisiae cells indicated that neutral amino acids such as glycine and alanine were probably excluded from the vacuoles, and that vacuolar H(+)-ATPase (V-ATPase) was involved in the vacuolar compartmentalization of these amino acids. We found that vacuolar membrane vesicles export neutral amino acids in an ATP-dependent manner. This is important in identifying vacuolar transporters for neutral amino acids.

  17. Saccharomyces cerevisiae populations and other yeasts associated with indigenous beers (chicha) of Ecuador.

    PubMed

    Piló, Fernanda Barbosa; Carvajal-Barriga, Enrique Javier; Guamán-Burneo, Maria Cristina; Portero-Barahona, Patricia; Dias, Arthur Matoso Morato; Freitas, Larissa Falabella Daher de; Gomes, Fátima de Cássia Oliveira; Rosa, Carlos Augusto

    2018-03-01

    Chicha, a type of beer made mainly with maize or cassava, is a traditional fermented beverage of the Andean region. There have only been a few studies on yeasts associated with chicha fermentation, and the species diversity occurring during the production of this beverage is not known. The objective of this study was to determine the biodiversity of yeasts in chicha, and to characterize the Saccharomyces cerevisiae populations associated with the production of chicha de jora, seven-grain chicha, chicha de yuca, and chicha de morocho in Ecuador. The molecular diversity of S. cerevisiae populations was determined by restriction polymorphism mitochondrial profiles. The beverages were characterized based on their physicochemical parameters. Twenty-six species were identified, and the most prevalent species were S. cerevisiae and Torulaspora delbrueckii. Other yeast species were isolated at low frequencies. Among 121 isolates of S. cerevisiae, 68 different mtDNA molecular profiles were identified. These results showed that chichas are fermented by a high number of different strains of S. cerevisiae. Some other species provided a minor contribution to the fermentation process. The chicha presented generally similar physicochemical parameters to those observed for other traditional fermented beverages, and can be considered as an acid fermented beverage. Copyright © 2018 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  18. Candida zemplinina can reduce acetic acid produced by Saccharomyces cerevisiae in sweet wine fermentations.

    PubMed

    Rantsiou, Kalliopi; Dolci, Paola; Giacosa, Simone; Torchio, Fabrizio; Tofalo, Rosanna; Torriani, Sandra; Suzzi, Giovanna; Rolle, Luca; Cocolin, Luca

    2012-03-01

    In this study we investigated the possibility of using Candida zemplinina, as a partner of Saccharomyces cerevisiae, in mixed fermentations of must with a high sugar content, in order to reduce its acetic acid production. Thirty-five C. zemplinina strains, which were isolated from different geographic regions, were molecularly characterized, and their fermentation performances were determined. Five genetically different strains were selected for mixed fermentations with S. cerevisiae. Two types of inoculation were carried out: coinoculation and sequential inoculation. A balance between the two species was generally observed for the first 6 days, after which the levels of C. zemplinina started to decrease. Relevant differences were observed concerning the consumption of sugars, the ethanol and glycerol content, and acetic acid production, depending on which strain was used and which type of inoculation was performed. Sequential inoculation led to the reduction of about half of the acetic acid content compared to the pure S. cerevisiae fermentation, but the ethanol and glycerol amounts were also low. A coinoculation with selected combinations of S. cerevisiae and C. zemplinina resulted in a decrease of ~0.3 g of acetic acid/liter, while maintaining high ethanol and glycerol levels. This study demonstrates that mixed S. cerevisiae and C. zemplinina fermentation could be applied in sweet wine fermentation to reduce the production of acetic acid, connected to the S. cerevisiae osmotic stress response.

  19. Expression in Escherichia coli of the Saccharomyces cerevisiae CCT gene encoding cholinephosphate cytidylyltransferase.

    PubMed Central

    Tsukagoshi, Y; Nikawa, J; Hosaka, K; Yamashita, S

    1991-01-01

    The coding region of the CCT gene from the yeast Saccharomyces cerevisiae was cloned into the pUC18 expression vector. The plasmid directed the synthesis of an active cholinephosphate cytidylyltransferase in Escherichia coli, confirming that CCT is the structural gene for this enzyme. The enzyme produced in E. coli efficiently utilized cholinephosphate and N,N-dimethylethanolaminephosphate, but N-methylethanolamine-phosphate and ethanolaminephosphate were poor substrates. Consistently, disruption of the CCT locus in the wild-type yeast cells resulted in a drastic decrease in activities with respect to the former two substrates. When activity was expressed in E. coli, over 90% was recovered in the cytosol, whereas most of the activity of yeast cells was associated with membranes, suggesting that yeast cells possess a mechanism that promotes membrane association of cytidylyltransferase. Images PMID:1848222

  20. Sugar and Glycerol Transport in Saccharomyces cerevisiae.

    PubMed

    Bisson, Linda F; Fan, Qingwen; Walker, Gordon A

    2016-01-01

    In Saccharomyces cerevisiae the process of transport of sugar substrates into the cell comprises a complex network of transporters and interacting regulatory mechanisms. Members of the large family of hexose (HXT) transporters display uptake efficiencies consistent with their environmental expression and play physiological roles in addition to feeding the glycolytic pathway. Multiple glucose-inducing and glucose-independent mechanisms serve to regulate expression of the sugar transporters in yeast assuring that expression levels and transporter activity are coordinated with cellular metabolism and energy needs. The expression of sugar transport activity is modulated by other nutritional and environmental factors that may override glucose-generated signals. Transporter expression and activity is regulated transcriptionally, post-transcriptionally and post-translationally. Recent studies have expanded upon this suite of regulatory mechanisms to include transcriptional expression fine tuning mediated by antisense RNA and prion-based regulation of transcription. Much remains to be learned about cell biology from the continued analysis of this dynamic process of substrate acquisition.

  1. Genome duplication and mutations in ACE2 cause multicellular, fast-sedimenting phenotypes in evolved Saccharomyces cerevisiae

    PubMed Central

    Oud, Bart; Guadalupe-Medina, Victor; Nijkamp, Jurgen F.; de Ridder, Dick; Pronk, Jack T.; van Maris, Antonius J. A.; Daran, Jean-Marc

    2013-01-01

    Laboratory evolution of the yeast Saccharomyces cerevisiae in bioreactor batch cultures yielded variants that grow as multicellular, fast-sedimenting clusters. Knowledge of the molecular basis of this phenomenon may contribute to the understanding of natural evolution of multicellularity and to manipulating cell sedimentation in laboratory and industrial applications of S. cerevisiae. Multicellular, fast-sedimenting lineages obtained from a haploid S. cerevisiae strain in two independent evolution experiments were analyzed by whole genome resequencing. The two evolved cell lines showed different frameshift mutations in a stretch of eight adenosines in ACE2, which encodes a transcriptional regulator involved in cell cycle control and mother-daughter cell separation. Introduction of the two ace2 mutant alleles into the haploid parental strain led to slow-sedimenting cell clusters that consisted of just a few cells, thus representing only a partial reconstruction of the evolved phenotype. In addition to single-nucleotide mutations, a whole-genome duplication event had occurred in both evolved multicellular strains. Construction of a diploid reference strain with two mutant ace2 alleles led to complete reconstruction of the multicellular-fast sedimenting phenotype. This study shows that whole-genome duplication and a frameshift mutation in ACE2 are sufficient to generate a fast-sedimenting, multicellular phenotype in S. cerevisiae. The nature of the ace2 mutations and their occurrence in two independent evolution experiments encompassing fewer than 500 generations of selective growth suggest that switching between unicellular and multicellular phenotypes may be relevant for competitiveness of S. cerevisiae in natural environments. PMID:24145419

  2. Analysis of the Saccharomyces cerevisiae pan-genome reveals a pool of copy number variants distributed in diverse yeast strains from differing industrial environments.

    PubMed

    Dunn, Barbara; Richter, Chandra; Kvitek, Daniel J; Pugh, Tom; Sherlock, Gavin

    2012-05-01

    Although the budding yeast Saccharomyces cerevisiae is arguably one of the most well-studied organisms on earth, the genome-wide variation within this species--i.e., its "pan-genome"--has been less explored. We created a multispecies microarray platform containing probes covering the genomes of several Saccharomyces species: S. cerevisiae, including regions not found in the standard laboratory S288c strain, as well as the mitochondrial and 2-μm circle genomes-plus S. paradoxus, S. mikatae, S. kudriavzevii, S. uvarum, S. kluyveri, and S. castellii. We performed array-Comparative Genomic Hybridization (aCGH) on 83 different S. cerevisiae strains collected across a wide range of habitats; of these, 69 were commercial wine strains, while the remaining 14 were from a diverse set of other industrial and natural environments. We observed interspecific hybridization events, introgression events, and pervasive copy number variation (CNV) in all but a few of the strains. These CNVs were distributed throughout the strains such that they did not produce any clear phylogeny, suggesting extensive mating in both industrial and wild strains. To validate our results and to determine whether apparently similar introgressions and CNVs were identical by descent or recurrent, we also performed whole-genome sequencing on nine of these strains. These data may help pinpoint genomic regions involved in adaptation to different industrial milieus, as well as shed light on the course of domestication of S. cerevisiae.

  3. Analysis of the Saccharomyces cerevisiae pan-genome reveals a pool of copy number variants distributed in diverse yeast strains from differing industrial environments

    PubMed Central

    Dunn, Barbara; Richter, Chandra; Kvitek, Daniel J.; Pugh, Tom; Sherlock, Gavin

    2012-01-01

    Although the budding yeast Saccharomyces cerevisiae is arguably one of the most well-studied organisms on earth, the genome-wide variation within this species—i.e., its “pan-genome”—has been less explored. We created a multispecies microarray platform containing probes covering the genomes of several Saccharomyces species: S. cerevisiae, including regions not found in the standard laboratory S288c strain, as well as the mitochondrial and 2-μm circle genomes–plus S. paradoxus, S. mikatae, S. kudriavzevii, S. uvarum, S. kluyveri, and S. castellii. We performed array-Comparative Genomic Hybridization (aCGH) on 83 different S. cerevisiae strains collected across a wide range of habitats; of these, 69 were commercial wine strains, while the remaining 14 were from a diverse set of other industrial and natural environments. We observed interspecific hybridization events, introgression events, and pervasive copy number variation (CNV) in all but a few of the strains. These CNVs were distributed throughout the strains such that they did not produce any clear phylogeny, suggesting extensive mating in both industrial and wild strains. To validate our results and to determine whether apparently similar introgressions and CNVs were identical by descent or recurrent, we also performed whole-genome sequencing on nine of these strains. These data may help pinpoint genomic regions involved in adaptation to different industrial milieus, as well as shed light on the course of domestication of S. cerevisiae. PMID:22369888

  4. Phenotypic evaluation and characterization of 21 industrial Saccharomyces cerevisiae yeast strains.

    PubMed

    Kong, In Iok; Turner, Timothy Lee; Kim, Heejin; Kim, Soo Rin; Jin, Yong-Su

    2018-02-01

    Microorganisms have been studied and used extensively to produce value-added fuels and chemicals. Yeasts, specifically Saccharomyces cerevisiae, receive industrial attention because of their well-known ability to ferment glucose and produce ethanol. Thousands of natural or genetically modified S. cerevisiae have been found in industrial environments for various purposes. These industrial strains are isolated from industrial fermentation sites, and they are considered as potential host strains for superior fermentation processes. In many cases, industrial yeast strains have higher thermotolerance, increased resistances towards fermentation inhibitors and increased glucose fermentation rates under anaerobic conditions when compared with laboratory yeast strains. Despite the advantages of industrial strains, they are often not well characterized. Through screening and phenotypic characterization of commercially available industrial yeast strains, industrial fermentation processes requiring specific environmental conditions may be able to select an ideal starting yeast strain to be further engineered. Here, we have characterized and compared 21 industrial S. cerevisiae strains under multiple conditions, including their tolerance to varying pH conditions, resistance to fermentation inhibitors, sporulation efficiency and ability to ferment lignocellulosic sugars. These data may be useful for the selection of a parental strain for specific biotechnological applications of engineered yeast. © FEMS 2018. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. Terminal acidic shock inhibits sour beer bottle conditioning by Saccharomyces cerevisiae.

    PubMed

    Rogers, Cody M; Veatch, Devon; Covey, Adam; Staton, Caleb; Bochman, Matthew L

    2016-08-01

    During beer fermentation, the brewer's yeast Saccharomyces cerevisiae experiences a variety of shifting growth conditions, culminating in a low-oxygen, low-nutrient, high-ethanol, acidic environment. In beers that are bottle conditioned (i.e., carbonated in the bottle by supplying yeast with a small amount of sugar to metabolize into CO2), the S. cerevisiae cells must overcome these stressors to perform the ultimate act in beer production. However, medium shock caused by any of these variables can slow, stall, or even kill the yeast, resulting in production delays and economic losses. Here, we describe a medium shock caused by high lactic acid levels in an American sour beer, which we refer to as "terminal acidic shock". Yeast exposed to this shock failed to bottle condition the beer, though they remained viable. The effects of low pH/high [lactic acid] conditions on the growth of six different brewing strains of S. cerevisiae were characterized, and we developed a method to adapt the yeast to growth in acidic beer, enabling proper bottle conditioning. Our findings will aid in the production of sour-style beers, a trending category in the American craft beer scene. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Redundancy of Saccharomyces cerevisiae MSH3 and MSH6 in MSH2-dependent mismatch repair.

    PubMed

    Marsischky, G T; Filosi, N; Kane, M F; Kolodner, R

    1996-02-15

    Saccharomyces cerevisiae encodes six genes, MSH1-6, which encode proteins related to the bacterial MutS protein. In this study the role of MSH2, MSH3, and MSH6 in mismatch repair has been examined by measuring the rate of accumulating mutations and mutation spectrum in strains containing different combinations of msh2, msh3, and msh6 mutations and by studying the physical interaction between the MSH2 protein and the MSH3 and MSH6 proteins. The results indicate that S. cerevisiae has two pathways of MSH2-dependent mismatch repair: one that recognized single-base mispairs and requires MSH2 and MSH6, and a second that recognizes insertion/deletion mispairs and requires a combination of either MSH2 and MSH6 or MSH2 and MSH3. The redundancy of MSH3 and MSH6 explains the greater prevalence of hmsh2 mutations in HNPCC families and suggests how the role of hmsh3 and hmsh6 mutations in cancer susceptibility could be analyzed.

  7. Metabolic engineering of Saccharomyces cerevisiae for overproduction of triacylglycerols.

    PubMed

    Ferreira, Raphael; Teixeira, Paulo Gonçalves; Gossing, Michael; David, Florian; Siewers, Verena; Nielsen, Jens

    2018-06-01

    Triacylglycerols (TAGs) are valuable versatile compounds that can be used as metabolites for nutrition and health, as well as feedstocks for biofuel production. Although Saccharomyces cerevisiae is the favored microbial cell factory for industrial production of biochemicals, it does not produce large amounts of lipids and TAGs comprise only ~1% of its cell dry weight. Here, we engineered S. cerevisiae to reorient its metabolism for overproduction of TAGs, by regulating lipid droplet associated-proteins involved in TAG synthesis and hydrolysis. We implemented a push-and-pull strategy by overexpressing genes encoding a deregulated acetyl-CoA carboxylase, ACC1 S659A/S1157A (ACC1**) , as well as the last two steps of TAG formation: phosphatidic phosphatase ( PAH1 ) and diacylglycerol acyltransferase ( DGA1 ), ultimately leading to 129 mg∙gCDW -1 of TAGs. Disruption of TAG lipase genes TGL3 , TGL4 , TGL5 and sterol acyltransferase gene ARE1 increased the TAG content to 218 mg∙gCDW -1 . Further disruption of the beta-oxidation by deletion of POX1 , as well as glycerol-3-phosphate utilization through deletion of GUT2 , did not affect TAGs levels. Finally, disruption of the peroxisomal fatty acyl-CoA transporter PXA1 led to accumulation of 254 mg∙gCDW -1 . The TAG levels achieved here are the highest titer reported in S. cerevisiae , reaching 27.4% of the maximum theoretical yield in minimal medium with 2% glucose. This work shows the potential of using an industrially established and robust yeast species for high level lipid production.

  8. Review of current methods for characterizing virulence and pathogenicity potential of industrial Saccharomyces cerevisiae strains towards humans.

    PubMed

    Anoop, Valar; Rotaru, Sever; Shwed, Philip S; Tayabali, Azam F; Arvanitakis, George

    2015-09-01

    Most industrial Saccharomyces cerevisiae strains used in food or biotechnology processes are benign. However, reports of S. cerevisiae infections have emerged and novel strains continue to be developed. In order to develop recommendations for the human health risk assessment of S. cerevisiae strains, we conducted a literature review of current methods used to characterize their pathogenic potential and evaluated their relevance towards risk assessment. These studies revealed that expression of virulence traits in S. cerevisiae is complex and depends on many factors. Given the opportunistic nature of this organism, an approach using multiple lines of evidence is likely necessary for the reasonable prediction of the pathogenic potential of a particular strain. Risk assessment of S. cerevisiae strains would benefit from more research towards the comparison of virulent and non-virulent strains in order to better understand those genotypic and phenotypic traits most likely to be associated with pathogenicity. © Her Majesty the Queen in Right of Canada 2015. Reproduced with the permission of the Minister of Health.

  9. Induction and Repression in the S-Adenosylmethionine and Methionine Biosynthetic Systems of Saccharomyces cerevisiae

    PubMed Central

    Ferro, A. J.; Spence, K. D.

    1973-01-01

    Two methionine biosynthetic enzymes and the methionine adenosyltransferase are repressed in Saccharomyces cerevisiae when grown under conditions where the intracellular levels of S-adenosylmethionine are high. The nature of the co-repressor molecule of this repression was investigated by following the intracellular levels of methionine, S-adenosylmethionine, and S-adenosylhomocysteine, as well as enzyme activities, after growth under various conditions. Under all of the conditions found to repress these enzymes, there is an accompanying induction of the S-adenosylmethionine-homocysteine methyltransferase which suggests that this enzyme may play a key role in the regulation of S-adenosylmethionine and methionine balance and synthesis. S-methylmethionine also induces the methyltransferase, but unlike S-adenosylmethionine, it does not repress the methionine adenosyltransferase or other methionine biosynthetic enzymes tested. PMID:4583251

  10. Natural and modified promoters for tailored metabolic engineering of the yeast Saccharomyces cerevisiae.

    PubMed

    Hubmann, Georg; Thevelein, Johan M; Nevoigt, Elke

    2014-01-01

    The ease of highly sophisticated genetic manipulations in the yeast Saccharomyces cerevisiae has initiated numerous initiatives towards development of metabolically engineered strains for novel applications beyond its traditional use in brewing, baking, and wine making. In fact, baker's yeast has become a key cell factory for the production of various bulk and fine chemicals. Successful metabolic engineering requires fine-tuned adjustments of metabolic fluxes and coordination of multiple pathways within the cell. This has mostly been achieved by controlling gene expression at the transcriptional level, i.e., by using promoters with appropriate strengths and regulatory properties. Here we present an overview of natural and modified promoters, which have been used in metabolic pathway engineering of S. cerevisiae. Recent developments in creating promoters with tailor-made properties are also discussed.

  11. Genetic Approaches to Study Meiosis and Meiosis-Specific Gene Expression in Saccharomyces cerevisiae.

    PubMed

    Kassir, Yona; Stuart, David T

    2017-01-01

    The budding yeast Saccharomyces cerevisiae has a long history as a model organism for studies of meiosis and the cell cycle. The popularity of this yeast as a model is in large part due to the variety of genetic and cytological approaches that can be effectively performed with the cells. Cultures of the cells can be induced to synchronously progress through meiosis and sporulation allowing large-scale gene expression and biochemical studies to be performed. Additionally, the spore tetrads resulting from meiosis make it possible to characterize the haploid products of meiosis allowing investigation of meiotic recombination and chromosome segregation. Here we describe genetic methods for analysis progression of S. cerevisiae through meiosis and sporulation with an emphasis on strategies for the genetic analysis of regulators of meiosis-specific genes.

  12. Dominance of Saccharomyces cerevisiae in alcoholic fermentation processes: role of physiological fitness and microbial interactions.

    PubMed

    Albergaria, Helena; Arneborg, Nils

    2016-03-01

    Winemaking, brewing and baking are some of the oldest biotechnological processes. In all of them, alcoholic fermentation is the main biotransformation and Saccharomyces cerevisiae the primary microorganism. Although a wide variety of microbial species may participate in alcoholic fermentation and contribute to the sensory properties of end-products, the yeast S. cerevisiae invariably dominates the final stages of fermentation. The ability of S. cerevisiae to outcompete other microbial species during alcoholic fermentation processes, such as winemaking, has traditionally been ascribed to its high fermentative power and capacity to withstand the harsh environmental conditions, i.e. high levels of ethanol and organic acids, low pH values, scarce oxygen availability and depletion of certain nutrients. However, in recent years, several studies have raised evidence that S. cerevisiae, beyond its remarkable fitness for alcoholic fermentation, also uses defensive strategies mediated by different mechanisms, such as cell-to-cell contact and secretion of antimicrobial peptides, to combat other microorganisms. In this paper, we review the main physiological features underlying the special aptitude of S. cerevisiae for alcoholic fermentation and discuss the role of microbial interactions in its dominance during alcoholic fermentation, as well as its relevance for winemaking.

  13. 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.

  14. Bioethanol production from cellulosic hydrolysates by engineered industrial Saccharomyces cerevisiae.

    PubMed

    Lee, Ye-Gi; Jin, Yong-Su; Cha, Young-Lok; Seo, Jin-Ho

    2017-03-01

    Even though industrial yeast strains exhibit numerous advantageous traits for the production of bioethanol, their genetic manipulation has been limited. This study demonstrates that an industrial polyploidy Saccharomyces cerevisiae JHS200 can be engineered through Cas9 (CRISPR associated protein 9)-based genome editing. Specifically, we generated auxotrophic mutants and introduced a xylose metabolic pathway into the auxotrophic mutants. As expected, the engineered strain (JX123) enhanced ethanol production from cellulosic hydrolysates as compared to other engineered haploid strains. However, the JX123 strain produced substantial amounts of xylitol as a by-product during xylose fermentation. Hypothesizing that the xylitol accumulation might be caused by intracellular redox imbalance from cofactor difference, the NADH oxidase from Lactococcus lactis was introduced into the JX123 strain. The resulting strain (JX123_noxE) not only produced more ethanol, but also produced xylitol less than the JX123 strain. These results suggest that industrial polyploidy yeast can be modified for producing biofuels and chemicals. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Hxt-carrier-mediated glucose efflux upon exposure of Saccharomyces cerevisiae to excess maltose.

    PubMed

    Jansen, Mickel L A; De Winde, Johannes H; Pronk, Jack T

    2002-09-01

    When wild-type Saccharomyces cerevisiae strains pregrown in maltose-limited chemostat cultures were exposed to excess maltose, release of glucose into the external medium was observed. Control experiments confirmed that glucose release was not caused by cell lysis or extracellular maltose hydrolysis. To test the hypothesis that glucose efflux involved plasma membrane glucose transporters, experiments were performed with an S. cerevisiae strain in which all members of the hexose transporter (HXT) gene family had been eliminated and with an isogenic reference strain. Glucose efflux was virtually eliminated in the hexose-transport-deficient strain. This constitutes experimental proof that Hxt transporters facilitate export of glucose from S. cerevisiae cells. After exposure of the hexose-transport-deficient strain to excess maltose, an increase in the intracellular glucose level was observed, while the concentrations of glucose 6-phosphate and ATP remained relatively low. These results demonstrate that glucose efflux can occur as a result of uncoordinated expression of the initial steps of maltose metabolism and the subsequent reactions in glucose dissimilation. This is a relevant phenomenon for selection of maltose-constitutive strains for baking and brewing.

  16. Potassium supply and homeostasis in the osmotolerant non-conventional yeasts Zygosaccharomyces rouxii differ from Saccharomyces cerevisiae.

    PubMed

    Stříbný, Jiří; Kinclová-Zimmermannová, Olga; Sychrová, Hana

    2012-12-01

    Three different transport systems exist to accumulate a sufficient amount of potassium cations in yeasts. The most common of these are Trk-type transporters, which are used by all yeast species. Though most yeast species employ two different types of transporters, we only identified one gene encoding a potassium uptake system (Trk-type) in the genome of the highly osmotolerant yeast Zygosaccharomyces rouxii, and our results showed that ZrTrk1 is its major (and probably only) specific potassium uptake system. When expressed in Saccharomyces cerevisiae, the product of the ZrTRK1 gene is localized to the plasma membrane and its presence efficiently complements the phenotypes of S. cerevisiae trk1∆ trk2∆ cells. Deletion of the ZrTRK1 gene resulted in Z. rouxii cells being almost incapable of growth at low K(+) concentrations and it changed some cell physiological parameters in a way that differs from S. cerevisiae. In contrast to S. cerevisiae, Z. rouxii cells without the TRK1 gene contained less potassium than the control cells and their plasma membrane was significantly hyperpolarized compared with those of the parental strain when grown in the presence of 100 mM KCl. On the other hand, subsequent potassium starvation led to a substantial depolarization which is again different from S. cerevisiae. Plasma-membrane hyperpolarization did not prevent the efflux of potassium from Z. rouxii trk1Δ cells during potassium starvation, and the activity of ZrPma1 is less affected by the absence of ZrTRK1 than in S. cerevisiae. The use of a newly constructed Z. rouxii-specific plasmid for the expression of pHluorin showed that the intracellular pH of the Z. rouxii wild type and the trk1∆ mutant is not significantly different. Together with the fact that Z. rouxii cells contain a significantly lower amount of intracellular potassium than identically grown S. cerevisiae cells, our results suggest that this highly osmotolerant yeast species maintain its intracellular pH and

  17. Production of pyruvate from mannitol by mannitol-assimilating pyruvate decarboxylase-negative Saccharomyces cerevisiae

    PubMed Central

    Yoshida, Shiori; Tanaka, Hideki; Hirayama, Makoto; Murata, Kousaku; Kawai, Shigeyuki

    2015-01-01

    Mannitol is contained in brown macroalgae up to 33% (w/w, dry weight), and thus is a promising carbon source for white biotechnology. However, Saccharomyces cerevisiae, a key cell factory, is generally regarded to be unable to assimilate mannitol for growth. We have recently succeeded in producing S. cerevisiae that can assimilate mannitol through spontaneous mutations of Tup1-Cyc8, each of which constitutes a general corepressor complex. In this study, we demonstrate production of pyruvate from mannitol using this mannitol-assimilating S. cerevisiae through deletions of all 3 pyruvate decarboxylase genes. The resultant mannitol-assimilating pyruvate decarboxylase-negative strain produced 0.86 g/L pyruvate without use of acetate after cultivation for 4 days, with an overall yield of 0.77 g of pyruvate per g of mannitol (the theoretical yield was 79%). Although acetate was not needed for growth of this strain in mannitol-containing medium, addition of acetate had a significant beneficial effect on production of pyruvate. This is the first report of production of a valuable compound (other than ethanol) from mannitol using S. cerevisiae, and is an initial platform from which the productivity of pyruvate from mannitol can be improved. PMID:26588105

  18. Hydrostatic Pressure Enhances Vital Staining with Carboxyfluorescein or Carboxydichlorofluorescein in Saccharomyces cerevisiae: Efficient Detection of Labeled Yeasts by Flow Cytometry

    PubMed Central

    Abe, Fumiyoshi

    1998-01-01

    The extent of intracellular accumulation of the fluorescent dye carboxyfluorescein or carboxydichlorofluorescein (CDCF) in Saccharomyces cerevisiae was found to be increased 5- to 10-fold under a nonlethal hydrostatic pressure of 30 to 50 MPa. This observation was confirmed by analysis of individual labeled cells by flow cytometry. The pressure-induced enhancement of staining with CDCF required d-glucose and was markedly inhibited by 2-deoxy-d-glucose, suggesting that glucose metabolism has a role in the process. PMID:9501452

  19. Saccharomyces cerevisiae as a Model to Study Replicative Senescence Triggered by Telomere Shortening

    PubMed Central

    Teixeira, M. Teresa

    2013-01-01

    In many somatic human tissues, telomeres shorten progressively because of the DNA-end replication problem. Consequently, cells cease to proliferate and are maintained in a metabolically viable state called replicative senescence. These cells are characterized by an activation of DNA damage checkpoints stemming from eroded telomeres, which are bypassed in many cancer cells. Hence, replicative senescence has been considered one of the most potent tumor suppressor pathways. However, the mechanism through which short telomeres trigger this cellular response is far from being understood. When telomerase is removed experimentally in Saccharomyces cerevisiae, telomere shortening also results in a gradual arrest of population growth, suggesting that replicative senescence also occurs in this unicellular eukaryote. In this review, we present the key steps that have contributed to the understanding of the mechanisms underlying the establishment of replicative senescence in budding yeast. As in mammals, signals stemming from short telomeres activate the DNA damage checkpoints, suggesting that the early cellular response to the shortest telomere(s) is conserved in evolution. Yet closer analysis reveals a complex picture in which the apparent single checkpoint response may result from a variety of telomeric alterations expressed in the absence of telomerase. Accordingly, the DNA replication of eroding telomeres appears as a critical challenge for senescing budding yeast cells and the easy manipulation of S. cerevisiae is providing insights into the way short telomeres are integrated into their chromatin and nuclear environments. Finally, the loss of telomerase in budding yeast triggers a more general metabolic alteration that remains largely unexplored. Thus, telomerase-deficient S. cerevisiae cells may have more common points than anticipated with somatic cells, in which telomerase depletion is naturally programed, thus potentially inspiring investigations in mammalian cells

  20. Switching the mode of sucrose utilization by Saccharomyces cerevisiae

    PubMed Central

    Badotti, Fernanda; Dário, Marcelo G; Alves, Sergio L; Cordioli, Maria Luiza A; Miletti, Luiz C; de Araujo, Pedro S; Stambuk, Boris U

    2008-01-01

    Background Overflow metabolism is an undesirable characteristic of aerobic cultures of Saccharomyces cerevisiae during biomass-directed processes. It results from elevated sugar consumption rates that cause a high substrate conversion to ethanol and other bi-products, severely affecting cell physiology, bioprocess performance, and biomass yields. Fed-batch culture, where sucrose consumption rates are controlled by the external addition of sugar aiming at its low concentrations in the fermentor, is the classical bioprocessing alternative to prevent sugar fermentation by yeasts. However, fed-batch fermentations present drawbacks that could be overcome by simpler batch cultures at relatively high (e.g. 20 g/L) initial sugar concentrations. In this study, a S. cerevisiae strain lacking invertase activity was engineered to transport sucrose into the cells through a low-affinity and low-capacity sucrose-H+ symport activity, and the growth kinetics and biomass yields on sucrose analyzed using simple batch cultures. Results We have deleted from the genome of a S. cerevisiae strain lacking invertase the high-affinity sucrose-H+ symporter encoded by the AGT1 gene. This strain could still grow efficiently on sucrose due to a low-affinity and low-capacity sucrose-H+ symport activity mediated by the MALx1 maltose permeases, and its further intracellular hydrolysis by cytoplasmic maltases. Although sucrose consumption by this engineered yeast strain was slower than with the parental yeast strain, the cells grew efficiently on sucrose due to an increased respiration of the carbon source. Consequently, this engineered yeast strain produced less ethanol and 1.5 to 2 times more biomass when cultivated in simple batch mode using 20 g/L sucrose as the carbon source. Conclusion Higher cell densities during batch cultures on 20 g/L sucrose were achieved by using a S. cerevisiae strain engineered in the sucrose uptake system. Such result was accomplished by effectively reducing sucrose

  1. Switching the mode of sucrose utilization by Saccharomyces cerevisiae.

    PubMed

    Badotti, Fernanda; Dário, Marcelo G; Alves, Sergio L; Cordioli, Maria Luiza A; Miletti, Luiz C; de Araujo, Pedro S; Stambuk, Boris U

    2008-02-27

    Overflow metabolism is an undesirable characteristic of aerobic cultures of Saccharomyces cerevisiae during biomass-directed processes. It results from elevated sugar consumption rates that cause a high substrate conversion to ethanol and other bi-products, severely affecting cell physiology, bioprocess performance, and biomass yields. Fed-batch culture, where sucrose consumption rates are controlled by the external addition of sugar aiming at its low concentrations in the fermentor, is the classical bioprocessing alternative to prevent sugar fermentation by yeasts. However, fed-batch fermentations present drawbacks that could be overcome by simpler batch cultures at relatively high (e.g. 20 g/L) initial sugar concentrations. In this study, a S. cerevisiae strain lacking invertase activity was engineered to transport sucrose into the cells through a low-affinity and low-capacity sucrose-H+ symport activity, and the growth kinetics and biomass yields on sucrose analyzed using simple batch cultures. We have deleted from the genome of a S. cerevisiae strain lacking invertase the high-affinity sucrose-H+ symporter encoded by the AGT1 gene. This strain could still grow efficiently on sucrose due to a low-affinity and low-capacity sucrose-H+ symport activity mediated by the MALx1 maltose permeases, and its further intracellular hydrolysis by cytoplasmic maltases. Although sucrose consumption by this engineered yeast strain was slower than with the parental yeast strain, the cells grew efficiently on sucrose due to an increased respiration of the carbon source. Consequently, this engineered yeast strain produced less ethanol and 1.5 to 2 times more biomass when cultivated in simple batch mode using 20 g/L sucrose as the carbon source. Higher cell densities during batch cultures on 20 g/L sucrose were achieved by using a S. cerevisiae strain engineered in the sucrose uptake system. Such result was accomplished by effectively reducing sucrose uptake by the yeast cells

  2. Biodegradation of zearalenone by Saccharomyces cerevisiae: Possible involvement of ZEN responsive proteins of the yeast.

    PubMed

    Zhang, Hongyin; Dong, Manjia; Yang, Qiya; Apaliya, Maurice Tibiru; Li, Jun; Zhang, Xiaoyun

    2016-06-30

    The mycotoxin zearalenone, also known as F-2 mycotoxin or RAL is a potent estrogenic metabolite produced by some Gibberella and Fusarium species. It is a common contaminant of cereal crops, livestock and poultry products. However, detoxification of zearalenone (ZEN) remains a challenge. Recently, biological approach for ZEN detoxification is being explored. In this study, we investigated the biodegradation of ZEN by using Saccharomyces cerevisiae and the possible mechanisms involved. The findings revealed that, after 48h of incubation of S. cerevisiae in combination with ZEN, the ZEN was completely degraded by S. cerevisiae. On the contrary, heat-killed cells and cell-free culture filtrates of S. cerevisiae could not degrade ZEN. Furthermore, addition of cycloheximide to S. cerevisiae combined with ZEN at time 0h prevented ZEN degradation, while addition of cycloheximide at 12h significantly slowed down degradation. The results also indicated cellular proteomics of S. cerevisiae. Several differential proteins were identified, most of which were related to basic metabolism. The findings revealed that, after 48h of incubating ZEN together with S. cerevisiae, ZEN was completely degraded by S. cerevisiae. The mechanisms involved in the degradation of ZEN by S. cerevisiae may be the production of associated intracellular and extracellular enzymes, which have the ability to degrade ZEN. In addition, there were some functional proteins produced by S. cerevisiae, indicating that the basic metabolism of S. cerevisiae was improved when ZEN was added. This novel discovery by the authors, will greatly contribute to the field of biodegradation of mycotoxin by antagonists. The authors also believed this innovation will open the grounds for further research and improvement of S. cerevisiae in the field of biodegradation. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Structural and functional analysis of 5S rRNA in Saccharomyces cerevisiae

    PubMed Central

    Kiparisov, S.; Sergiev, P. V.; Dontsova, O. A.; Petrov, A.; Meskauskas, A.; Dinman, J. D.

    2005-01-01

    5S rRNA extends from the central protuberance of the large ribosomal subunit, through the A-site finger, and down to the GTPase-associated center. Here, we present a structure-function analysis of seven 5S rRNA alleles which are sufficient for viability in the yeast Saccharomyces cerevisiae when expressed in the absence of wild-type 5S rRNAs, and extend this analysis using a large bank of mutant alleles that show semidominant phenotypes in the presence of wild-type 5S rRNA. This analysis supports the hypothesis that 5S rRNA serves to link together several different functional centers of the ribosome. Data are also presented which suggest that in eukaryotic genomes selection has favored the maintenance of multiple alleles of 5S rRNA, and that these may provide cells with a mechanism to post-transcriptionally regulate gene expression. PMID:16047201

  4. Mechanisms of iron sensing and regulation in the yeast Saccharomyces cerevisiae.

    PubMed

    Martínez-Pastor, María Teresa; Perea-García, Ana; Puig, Sergi

    2017-04-01

    Iron is a redox active element that functions as an essential cofactor in multiple metabolic pathways, including respiration, DNA synthesis and translation. While indispensable for eukaryotic life, excess iron can lead to oxidative damage of macromolecules. Therefore, living organisms have developed sophisticated strategies to optimally regulate iron acquisition, storage and utilization in response to fluctuations in environmental iron bioavailability. In the yeast Saccharomyces cerevisiae, transcription factors Aft1/Aft2 and Yap5 regulate iron metabolism in response to low and high iron levels, respectively. In addition to producing and assembling iron cofactors, mitochondrial iron-sulfur (Fe/S) cluster biogenesis has emerged as a central player in iron sensing. A mitochondrial signal derived from Fe/S synthesis is exported and converted into an Fe/S cluster that interacts directly with Aft1/Aft2 and Yap5 proteins to regulate their transcriptional function. Various conserved proteins, such as ABC mitochondrial transporter Atm1 and, for Aft1/Aft2, monothiol glutaredoxins Grx3 and Grx4 are implicated in this iron-signaling pathway. The analysis of a wide range of S. cerevisiae strains of different geographical origins and sources has shown that yeast strains adapted to high iron display growth defects under iron-deficient conditions, and highlighted connections that exist in the response to both opposite conditions. Changes in iron accumulation and gene expression profiles suggest differences in the regulation of iron homeostasis genes.

  5. Dual utilization of NADPH and NADH cofactors enhances xylitol production in engineered Saccharomyces cerevisiae.

    PubMed

    Jo, Jung-Hyun; Oh, Sun-Young; Lee, Hyeun-Soo; Park, Yong-Cheol; Seo, Jin-Ho

    2015-12-01

    Xylitol, a natural sweetener, can be produced by hydrogenation of xylose in hemicelluloses. In microbial processes, utilization of only NADPH cofactor limited commercialization of xylitol biosynthesis. To overcome this drawback, Saccharomyces cerevisiae D452-2 was engineered to express two types of xylose reductase (XR) with either NADPH-dependence or NADH-preference. Engineered S. cerevisiae DWM expressing both the XRs exhibited higher xylitol productivity than the yeast strain expressing NADPH-dependent XR only (DWW) in both batch and glucose-limited fed-batch cultures. Furthermore, the coexpression of S. cerevisiae ZWF1 and ACS1 genes in the DWM strain increased intracellular concentrations of NADPH and NADH and improved maximum xylitol productivity by 17%, relative to that for the DWM strain. Finally, the optimized fed-batch fermentation of S. cerevisiae DWM-ZWF1-ACS1 resulted in 196.2 g/L xylitol concentration, 4.27 g/L h productivity and almost the theoretical yield. Expression of the two types of XR utilizing both NADPH and NADH is a promising strategy to meet the industrial demands for microbial xylitol production. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Whole-Genome Comparison Reveals Novel Genetic Elements That Characterize the Genome of Industrial Strains of Saccharomyces cerevisiae

    PubMed Central

    Borneman, Anthony R.; Desany, Brian A.; Riches, David; Affourtit, Jason P.; Forgan, Angus H.; Pretorius, Isak S.; Egholm, Michael; Chambers, Paul J.

    2011-01-01

    Human intervention has subjected the yeast Saccharomyces cerevisiae to multiple rounds of independent domestication and thousands of generations of artificial selection. As a result, this species comprises a genetically diverse collection of natural isolates as well as domesticated strains that are used in specific industrial applications. However the scope of genetic diversity that was captured during the domesticated evolution of the industrial representatives of this important organism remains to be determined. To begin to address this, we have produced whole-genome assemblies of six commercial strains of S. cerevisiae (four wine and two brewing strains). These represent the first genome assemblies produced from S. cerevisiae strains in their industrially-used forms and the first high-quality assemblies for S. cerevisiae strains used in brewing. By comparing these sequences to six existing high-coverage S. cerevisiae genome assemblies, clear signatures were found that defined each industrial class of yeast. This genetic variation was comprised of both single nucleotide polymorphisms and large-scale insertions and deletions, with the latter often being associated with ORF heterogeneity between strains. This included the discovery of more than twenty probable genes that had not been identified previously in the S. cerevisiae genome. Comparison of this large number of S. cerevisiae strains also enabled the characterization of a cluster of five ORFs that have integrated into the genomes of the wine and bioethanol strains on multiple occasions and at diverse genomic locations via what appears to involve the resolution of a circular DNA intermediate. This work suggests that, despite the scrutiny that has been directed at the yeast genome, there remains a significant reservoir of ORFs and novel modes of genetic transmission that may have significant phenotypic impact in this important model and industrial species. PMID:21304888

  7. Nanoscale Effects of Caspofungin against Two Yeast Species, Saccharomyces cerevisiae and Candida albicans

    PubMed Central

    Formosa, C.; Schiavone, M.; Martin-Yken, H.; François, J. M.; Duval, R. E.

    2013-01-01

    Saccharomyces cerevisiae and Candida albicans are model yeasts for biotechnology and human health, respectively. We used atomic force microscopy (AFM) to explore the effects of caspofungin, an antifungal drug used in hospitals, on these two species. Our nanoscale investigation revealed similar, but also different, behaviors of the two yeasts in response to treatment with the drug. While administration of caspofungin induced deep cell wall remodeling in both yeast species, as evidenced by a dramatic increase in chitin and decrease in β-glucan content, changes in cell wall composition were more pronounced with C. albicans cells. Notably, the increase of chitin was proportional to the increase in the caspofungin dose. In addition, the Young modulus of the cell was three times lower for C. albicans cells than for S. cerevisiae cells and increased proportionally with the increase of chitin, suggesting differences in the molecular organization of the cell wall between the two yeast species. Also, at a low dose of caspofungin (i.e., 0.5× MIC), the cell surface of C. albicans exhibited a morphology that was reminiscent of cells expressing adhesion proteins. Interestingly, this morphology was lost at high doses of the drug (i.e., 4× MIC). However, the treatment of S. cerevisiae cells with high doses of caspofungin resulted in impairment of cytokinesis. Altogether, the use of AFM for investigating the effects of antifungal drugs is relevant in nanomedicine, as it should help in understanding their mechanisms of action on fungal cells, as well as unraveling unexpected effects on cell division and fungal adhesion. PMID:23669379

  8. Apoptosis-inducing factor (Aif1) mediates anacardic acid-induced apoptosis in Saccharomyces cerevisiae.

    PubMed

    Muzaffar, Suhail; Chattoo, Bharat B

    2017-03-01

    Anacardic acid is a medicinal phytochemical that inhibits proliferation of fungal as well as several types of cancer cells. It induces apoptotic cell death in various cell types, but very little is known about the mechanism involved in the process. Here, we used budding yeast Saccharomyces cerevisiae as a model to study the involvement of some key elements of apoptosis in the anacardic acid-induced cell death. Plasma membrane constriction, chromatin condensation, DNA degradation, and externalization of phosphatidylserine (PS) indicated that anacardic acid induces apoptotic cell death in S. cerevisiae. However, the exogenous addition of broad-spectrum caspase inhibitor Z-VAD-FMK or deletion of the yeast caspase Yca1 showed that the anacardic acid-induced cell death is caspase independent. Apoptosis-inducing factor (AIF1) deletion mutant was resistant to the anacardic acid-induced cell death, suggesting a key role of Aif1. Overexpression of Aif1 made cells highly susceptible to anacardic acid, further confirming that Aif1 mediates anacardic acid-induced apoptosis. Interestingly, instead of the increase in the intracellular reactive oxygen species (ROS) normally observed during apoptosis, anacardic acid caused a decrease in the intracellular ROS levels. Quantitative real-time PCR analysis showed downregulation of the BIR1 survivin mRNA expression during the anacardic acid-induced apoptosis.

  9. Long-chain alkane production by the yeast Saccharomyces cerevisiae.

    PubMed

    Buijs, Nicolaas A; Zhou, Yongjin J; Siewers, Verena; Nielsen, Jens

    2015-06-01

    In the past decade industrial-scale production of renewable transportation biofuels has been developed as an alternative to fossil fuels, with ethanol as the most prominent biofuel and yeast as the production organism of choice. However, ethanol is a less efficient substitute fuel for heavy-duty and maritime transportation as well as aviation due to its low energy density. Therefore, new types of biofuels, such as alkanes, are being developed that can be used as drop-in fuels and can substitute gasoline, diesel, and kerosene. Here, we describe for the first time the heterologous biosynthesis of long-chain alkanes by the yeast Saccharomyces cerevisiae. We show that elimination of the hexadecenal dehydrogenase Hfd1 and expression of a redox system are essential for alkane biosynthesis in yeast. Deletion of HFD1 together with expression of an alkane biosynthesis pathway resulted in the production of the alkanes tridecane, pentadecane, and heptadecane. Our study provides a proof of principle for producing long-chain alkanes in the industrial workhorse S. cerevisiae, which was so far limited to bacteria. We anticipate that these findings will be a key factor for further yeast engineering to enable industrial production of alkane based drop-in biofuels, which can allow the biofuel industry to diversify beyond bioethanol. © 2014 Wiley Periodicals, Inc.

  10. Copper Tolerance and Biosorption of Saccharomyces cerevisiae during Alcoholic Fermentation

    PubMed Central

    Liu, Ling-ling; Jia, Bo; Zhao, Fang; Huang, Wei-dong; Zhan, Ji-cheng

    2015-01-01

    At high levels, copper in grape mash can inhibit yeast activity and cause stuck fermentations. Wine yeast has limited tolerance of copper and can reduce copper levels in wine during fermentation. This study aimed to understand copper tolerance of wine yeast and establish the mechanism by which yeast decreases copper in the must during fermentation. Three strains of Saccharomyces cerevisiae (lab selected strain BH8 and industrial strains AWRI R2 and Freddo) and a simple model fermentation system containing 0 to 1.50 mM Cu2+ were used. ICP-AES determined Cu ion concentration in the must decreasing differently by strains and initial copper levels during fermentation. Fermentation performance was heavily inhibited under copper stress, paralleled a decrease in viable cell numbers. Strain BH8 showed higher copper-tolerance than strain AWRI R2 and higher adsorption than Freddo. Yeast cell surface depression and intracellular structure deformation after copper treatment were observed by scanning electron microscopy and transmission electron microscopy; electronic differential system detected higher surface Cu and no intracellular Cu on 1.50 mM copper treated yeast cells. It is most probably that surface adsorption dominated the biosorption process of Cu2+ for strain BH8, with saturation being accomplished in 24 h. This study demonstrated that Saccharomyces cerevisiae strain BH8 has good tolerance and adsorption of Cu, and reduces Cu2+ concentrations during fermentation in simple model system mainly through surface adsorption. The results indicate that the strain selected from China’s stress-tolerant wine grape is copper tolerant and can reduce copper in must when fermenting in a copper rich simple model system, and provided information for studies on mechanisms of heavy metal stress. PMID:26030864

  11. The ASP3 locus in Saccharomyces cerevisiae originated by horizontal gene transfer from Wickerhamomyces.

    PubMed

    League, Garrett P; Slot, Jason C; Rokas, Antonis

    2012-11-01

    The asparagine degradation pathway in the S288c laboratory strain of Saccharomyces cerevisiae is comprised of genes located at two separate loci. ASP1 is located on chromosome IV and encodes for cytosolic l-asparaginase I, whereas ASP3 contains a gene cluster located on chromosome XII comprised of four identical genes, ASP3-1, ASP3-2, ASP3-3, and ASP3-4, which encode for cell wall-associated l-asparaginase II. Interestingly, the ASP3 locus appears to be only present, in variable copy number, in S. cerevisiae strains isolated from laboratory or industrial environments and is completely absent from the genomes of 128 diverse fungal species. Investigation of the evolutionary history of ASP3 across these 128 genomes as well as across the genomes of 43 S. cerevisiae strains shows that ASP3 likely arose in a S. cerevisiae strain via horizontal gene transfer (HGT) from, or a close relative of, the wine yeast Wickerhamomyces anomalus, which co-occurs with S. cerevisiae in several biotechnological processes. Thus, because the ASP3 present in the S288c laboratory strain of S. cerevisiae is induced in response to nitrogen starvation, its acquisition may have aided yeast adaptation to artificial environments. Our finding that the ASP3 locus in S. cerevisiae originated via HGT further highlights the importance of gene sharing between yeasts in the evolution of their remarkable metabolic diversity. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  12. Aberrant Synthesis of Indole-3-Acetic Acid in Saccharomyces cerevisiae Triggers Morphogenic Transition, a Virulence Trait of Pathogenic Fungi

    PubMed Central

    Rao, Reeta Prusty; Hunter, Ally; Kashpur, Olga; Normanly, Jennifer

    2010-01-01

    Many plant-associated microbes synthesize the auxin indole-3-acetic acid (IAA), and several IAA biosynthetic pathways have been identified in microbes and plants. Saccharomyces cerevisiae has previously been shown to respond to IAA by inducing pseudohyphal growth. We observed that IAA also induced hyphal growth in the human pathogen Candida albicans and thus may function as a secondary metabolite signal that regulates virulence traits such as hyphal transition in pathogenic fungi. Aldehyde dehydrogenase (Ald) is required for IAA synthesis from a tryptophan (Trp) precursor in Ustilago maydis. Mutant S. cerevisiae with deletions in two ALD genes are unable to convert radiolabeled Trp to IAA, yet produce IAA in the absence of exogenous Trp and at levels higher than wild type. These data suggest that yeast may have multiple pathways for IAA synthesis, one of which is not dependent on Trp. PMID:20233857

  13. Synergic treatment for monosodium glutamate wastewater by Saccharomyces cerevisiae and Coriolus versicolor.

    PubMed

    Jia, Cuiying; Kang, Ruijuan; Zhang, Yuhui; Cong, Wei; Cai, Zhaoling

    2007-03-01

    Biodegradation and decolorization of monosodium glutamate wastewater were carried out by using an acidophilus yeast strain of Saccharomyces cerevisiae and Coriolus versicolor. For the yeast treatment, the highest COD removal and reducing sugar removal efficiency were 76.6% and 80.2%, respectively. The color removal was only 2%. For C. versicolor treatment, the highest COD removal, color removal and reducing sugar removal efficiencies were 78.7%, 56.5% and 90.9%, respectively. The synergic treatment process, in which the yeast and C. versicolor were successively applied,exhibited great advantage over the individual process.

  14. Alternative Saccharomyces interspecies hybrid combinations and their potential for low‐temperature wort fermentation

    PubMed Central

    Nikulin, Jarkko; Krogerus, Kristoffer

    2017-01-01

    Abstract The lager yeast hybrid (Saccharomyces cerevisiae × Saccharomyces eubayanus) possesses two key characteristics that are essential for lager brewing: efficient sugar utilization and cold tolerance. Here we explore the possibility that the lager yeast phenotype can be recreated by hybridizing S. cerevisiae ale yeast with a number of cold‐tolerant Saccharomyces species including Saccharomyces arboricola, Saccharomyces eubayanus, Saccharomyces mikatae and Saccharomyces uvarum. Interspecies hybrids performed better than parental strains in lager brewing conditions (12°C and 12°P wort), with the S. mikatae hybrid performing as well as the S. eubayanus hybrid. Where the S. cerevisiae parent was capable of utilizing maltotriose, this trait was inherited by the hybrids. A greater production of higher alcohols and esters by the hybrids resulted in the production of more aromatic beers relative to the parents. Strong fermentation performance relative to the parents was dependent on ploidy, with polyploid hybrids (3n, 4n) performing better than diploid hybrids. All hybrids produced 4‐vinyl guaiacol, a smoke/clove aroma generally considered an off flavour in lager beer. This characteristic could however be eliminated by isolating spore clones from a fertile hybrid of S. cerevisiae and S. mikatae. The results suggest that S. eubayanus is dispensable when constructing yeast hybrids that express the typical lager yeast phenotype. © 2017 The Authors. Yeast published by John Wiley & Sons, Ltd. PMID:28755430

  15. Enzymatic activities produced by mixed Saccharomyces and non-Saccharomyces cultures: relationship with wine volatile composition.

    PubMed

    Maturano, Yolanda Paola; Assof, Mariela; Fabani, María Paula; Nally, María Cristina; Jofré, Viviana; Rodríguez Assaf, Leticia Anahí; Toro, María Eugenia; Castellanos de Figueroa, Lucía Inés; Vazquez, Fabio

    2015-11-01

    During certain wine fermentation processes, yeasts, and mainly non-Saccharomyces strains, produce and secrete enzymes such as β-glucosidases, proteases, pectinases, xylanases and amylases. The effects of enzyme activity on the aromatic quality of wines during grape juice fermentation, using different co-inoculation strategies of non-Saccharomyces and Saccharomyces cerevisiae yeasts, were assessed in the current study. Three strains with appropriate enological performance and high enzymatic activities, BSc562 (S. cerevisiae), BDv566 (Debaryomyces vanrijiae) and BCs403 (Candida sake), were assayed in pure and mixed Saccharomyces/non-Saccharomyces cultures. β-Glucosidase, pectinase, protease, xylanase and amylase activities were quantified during fermentations. The aromatic profile of pure and mixed cultures was determined at the end of each fermentation. In mixed cultures, non-Saccharomyces species were detected until day 4-5 of the fermentation process, and highest populations were observed in MSD2 (10% S. cerevisiae/90% D. vanrijiae) and MSC1 (1% S. cerevisiae/99% C. sake). According to correlation and multivariate analysis, MSD2 presented the highest concentrations of terpenes and higher alcohols which were associated with pectinase, amylase and xylanase activities. On the other hand, MSC1 high levels of β-glucosidase, proteolytic and xylanolytic activities were correlated to esters and fatty acids. Our study contributes to a better understanding of the effect of enzymatic activities by yeasts on compound transformations that occur during wine fermentation.

  16. Physico-chemical pretreatment and enzymatic hydrolysis of cotton stalk for ethanol production by Saccharomyces cerevisiae.

    PubMed

    Singh, Anita; Bajar, Somvir; Bishnoi, Narsi R

    2017-11-01

    The aim of this work was to study the physico-chemical pretreatment and enzymatic hydrolysis of cotton stalk for ethanol production by Saccharomyces cerevisiae. Firstly, factors affecting pretreatment were screened out by Plackett-Burman design (PBD) and most significant factors were further optimized by Box-Behnken design (BBD). As shown by experimental study, most significant factors were FeCl 3 concentration (FC), irradiation time (IT) and substrate concentration (SC) affecting pretreatment of cotton stalk among all studied factors. Under optimum conditions of pretreatment FC 0.15mol/l, IT 20min and SC 55g/l, the release of reducing sugar was 6.6g/l. Hydrolysis of pretreated cotton stalk was done by crude on-site produced enzymes and hydrolysate was concentrated. Ethanol production by Saccharomyces cerevisiae using concentrated cotton stalk hydrolysate was 9.8g p /l, with ethanol yield 0.37g p /g s on consumed sugars. The data indicated that microwave FeCl 3 pretreated cotton stalk hydrolyses by crude unprocessed enzyme cocktail was good, and ethanol can be produced by fermentation of hydrolysate. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Effective inactivation of Saccharomyces cerevisiae in minimally processed Makgeolli using low-pressure homogenization-based pasteurization.

    PubMed

    Bak, Jin Seop

    2015-01-01

    In order to address the limitations associated with the inefficient pasteurization platform used to make Makgeolli, such as the presence of turbid colloidal dispersions in suspension, commercially available Makgeolli was minimally processed using a low-pressure homogenization-based pasteurization (LHBP) process. This continuous process demonstrates that promptly reducing the exposure time to excessive heat using either large molecules or insoluble particles can dramatically improve internal quality and decrease irreversible damage. Specifically, optimal homogenization increased concomitantly with physical parameters such as colloidal stability (65.0% of maximum and below 25-μm particles) following two repetitions at 25.0 MPa. However, biochemical parameters such as microbial population, acidity, and the presence of fermentable sugars rarely affected Makgeolli quality. Remarkably, there was a 4.5-log reduction in the number of Saccharomyces cerevisiae target cells at 53.5°C for 70 sec in optimally homogenized Makgeolli. This value was higher than the 37.7% measured from traditionally pasteurized Makgeolli. In contrast to the analytical similarity among homogenized Makgeollis, our objective quality evaluation demonstrated significant differences between pasteurized (or unpasteurized) Makgeolli and LHBP-treated Makgeolli. Low-pressure homogenization-based pasteurization, Makgeolli, minimal processing-preservation, Saccharomyces cerevisiae, suspension stability.

  18. Increased mannoprotein content in wines produced by Saccharomyces kudriavzevii×Saccharomyces cerevisiae hybrids.

    PubMed

    Pérez-Través, Laura; Querol, Amparo; Pérez-Torrado, Roberto

    2016-11-21

    Several wine quality aspects are influenced by yeast mannoproteins on account of aroma compounds retention, lactic-acid bacterial growth stimulation, protection against protein haze and astringency reduction. Thus selecting a yeast strain that produces high levels of mannoproteins is important for the winemaking industry. In this work, we observed increased levels of mannoproteins in S. cerevisiae×S. kudriavzevii hybrids, compared to the S. cerevisiae strain, in wine fermentations. Furthermore, the expression of a key gene related to mannoproteins biosynthesis, PMT1, increased in the S. cerevisiae×S. kudriavzevii hybrid. We showed that artificially constructed S. cerevisiae×S. kudriavzevii hybrids also increased the levels of mannoproteins. This work demonstrates that either natural or artificial S. cerevisiae×S. kudriavzevii hybrids present mannoprotein overproducing capacity under winemaking conditions, a desirable physiological feature for this industry. These results suggest that genome interaction in hybrids generates a physiological environment that enhances the release of mannoproteins. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Comparison of Fermentation and Wines Produced by Inoculation of Hanseniaspora vineae and Saccharomyces cerevisiae

    PubMed Central

    Lleixà, Jessica; Martín, Valentina; Portillo, María del C.; Carrau, Francisco; Beltran, Gemma; Mas, Albert

    2016-01-01

    Interest in the use of non-Saccharomyces yeasts in winemaking has been increasing due to their positive contributions to wine quality. The non-Saccharomyces yeast Hanseniaspora vineae is an apiculate yeast that has been associated with the production of wine with good aromatic properties. However, little is known about the fermentation dynamics of H. vineae in natural must and its interaction with autochthonous yeasts. In the present study, we performed semi industrial fermentations of Macabeo and Merlot musts inoculated with either H. vineae or S. cerevisiae. The yeast population dynamics were monitored by plate culturing, PCR-DGGE and massive sequencing techniques. The results obtained with these techniques show that H. vineae was able dominate the autochthonous microbiota in Macabeo must but not in Merlot must, which exhibited a larger, more diverse yeast population. The presence of H. vineae throughout most of the Macabeo fermentation resulted in more fruity and flowery wine, as indicated by the chemical analysis of the final wines, which demonstrated a strong presence of phenyl ethyl acetate at concentrations higher than the threshold of perception and approximately 50 times more than that produced in wines fermented with S. cerevisiae. This compound is associated with fruity, floral and honey aromas. PMID:27014252

  20. Adaptation and major chromosomal changes in populations of Saccharomyces cerevisiae.

    PubMed

    Adams, J; Puskas-Rozsa, S; Simlar, J; Wilke, C M

    1992-07-01

    Thirteen independent populations of Saccharomyces cerevisiae (nine haploid and four diploid) were maintained in continuous culture for up to approximately 1000 generations, with growth limited by the concentration of organic phosphates in medium buffered at pH 6. Analysis of clones isolated from these populations showed that a number (17) of large-scale chromosomal-length variants and rearrangements were present in the populations at their termination. Nine of the 16 yeast chromosomes were involved in such changes. Few of the changes could be explained by copy-number increases in the structural loci for acid phosphatase. Several considerations concerning the nature and frequency of the chromosome-length variants observed lead us to conclude that they are selectively advantageous.

  1. Influence of genetic background of engineered xylose-fermenting industrial Saccharomyces cerevisiae strains for ethanol production from lignocellulosic hydrolysates

    USDA-ARS?s Scientific Manuscript database

    An industrial ethanol-producing Saccharomyces cerevisiae strain with genes needed for xylose-fermentation integrated into its genome was used to obtain haploids and diploid isogenic strains. The isogenic strains were more effective in metabolizing xylose than their parental strain (p < 0.05) and abl...

  2. 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.

  3. Responses of Saccharomyces cerevisiae Strains from Different Origins to Elevated Iron Concentrations

    PubMed Central

    Martínez-Garay, Carlos Andrés; de Llanos, Rosa; Romero, Antonia María; Martínez-Pastor, María Teresa

    2016-01-01

    Iron is an essential micronutrient for all eukaryotic organisms. However, the low solubility of ferric iron has tremendously increased the prevalence of iron deficiency anemia, especially in women and children, with dramatic consequences. Baker's yeast Saccharomyces cerevisiae is used as a model eukaryotic organism, a fermentative microorganism, and a feed supplement. In this report, we explore the genetic diversity of 123 wild and domestic strains of S. cerevisiae isolated from different geographical origins and sources to characterize how yeast cells respond to elevated iron concentrations in the environment. By using two different forms of iron, we selected and characterized both iron-sensitive and iron-resistant yeast strains. We observed that when the iron concentration in the medium increases, iron-sensitive strains accumulate iron more rapidly than iron-resistant isolates. We observed that, consistent with excess iron leading to oxidative stress, the redox state of iron-sensitive strains was more oxidized than that of iron-resistant strains. Growth assays in the presence of different oxidative reagents ruled out that this phenotype was due to alterations in the general oxidative stress protection machinery. It was noteworthy that iron-resistant strains were more sensitive to iron deficiency conditions than iron-sensitive strains, which suggests that adaptation to either high or low iron is detrimental for the opposite condition. An initial gene expression analysis suggested that alterations in iron homeostasis genes could contribute to the different responses of distant iron-sensitive and iron-resistant yeast strains to elevated environmental iron levels. PMID:26773083

  4. Effects of supplementing Saccharomyces cerevisiae fermentation product in sow diets on performance of sows and nursing piglets

    USDA-ARS?s Scientific Manuscript database

    Forty-two sows were used to determine the effects of adding Saccharomyces cerevisiae fermentation product to gestation and lactation diets on performance of sows and their progeny. On 5 d before breeding, sows were allotted to 2 dietary treatments representing: (1) sows fed a diet with 12.0 g fermen...

  5. Yield improvement of heterologous peptides expressed in yps1-disrupted Saccharomyces cerevisiae strains.

    PubMed

    Egel-Mitani; Andersen; Diers; Hach; Thim; Hastrup; Vad

    2000-06-01

    Heterologous protein expression levels in Saccharomyces cerevisiae fermentations are highly dependent on the susceptibility to endogenous yeast proteases. Small peptides, such as glucagon and glucagon-like-peptides (GLP-1 and GLP-2), featuring an open structure are particularly accessible for proteolytic degradation during fermentation. Therefore, homogeneous products cannot be obtained. The most sensitive residues are found at basic amino acid residues in the peptide sequence. These heterologous peptides are degraded mainly by the YPS1-encoded aspartic protease, yapsin1, when produced in the yeast. In this article, distinct degradation products were analyzed by HPLC and mass spectrometry, and high yield of the heterologous peptide production has been achieved by the disruption of the YPS1 gene (previously called YAP3). By this technique, high yield continuous fermentation of glucagon in S. cerevisiae is now possible.

  6. The resistance of the yeast Saccharomyces cerevisiae to the biocide polyhexamethylene biguanide: involvement of cell wall integrity pathway and emerging role for YAP1.

    PubMed

    Elsztein, Carolina; de Lucena, Rodrigo M; de Morais, Marcos A

    2011-08-19

    Polyhexamethylene biguanide (PHMB) is an antiseptic polymer that is mainly used for cleaning hospitals and pools and combating Acantamoeba infection. Its fungicide activity was recently shown by its lethal effect on yeasts that contaminate the industrial ethanol process, and on the PE-2 strain of Saccharomyces cerevisiae, one of the main fermenting yeasts in Brazil. This pointed to the need to know the molecular mechanism that lay behind the cell resistance to this compound. In this study, we examined the factors involved in PHMB-cell interaction and the mechanisms that respond to the damage caused by this interaction. To achieve this, two research strategies were employed: the expression of some genes by RT-qPCR and the analysis of mutant strains. Cell Wall integrity (CWI) genes were induced in the PHMB-resistant Saccharomyces cerevisiae strain JP-1, although they are poorly expressed in the PHMB-sensitive Saccharomyces cerevisiae PE2 strain. This suggested that PHMB damages the glucan structure on the yeast cell wall. It was also confirmed by the observed sensitivity of the yeast deletion strains, Δslg1, Δrom2, Δmkk2, Δslt2, Δknr4, Δswi4 and Δswi4, which showed that the protein kinase C (PKC) regulatory mechanism is involved in the response and resistance to PHMB. The sensitivity of the Δhog1 mutant was also observed. Furthermore, the cytotoxicity assay and gene expression analysis showed that the part played by YAP1 and CTT1 genes in cell resistance to PHMB is unrelated to oxidative stress response. Thus, we suggested that Yap1p can play a role in cell wall maintenance by controlling the expression of the CWI genes. The PHMB treatment of the yeast cells activates the PKC1/Slt2 (CWI) pathway. In addition, it is suggested that HOG1 and YAP1 can play a role in the regulation of CWI genes.

  7. The resistance of the yeast Saccharomyces cerevisiae to the biocide polyhexamethylene biguanide: involvement of cell wall integrity pathway and emerging role for YAP1

    PubMed Central

    2011-01-01

    Background Polyhexamethylene biguanide (PHMB) is an antiseptic polymer that is mainly used for cleaning hospitals and pools and combating Acantamoeba infection. Its fungicide activity was recently shown by its lethal effect on yeasts that contaminate the industrial ethanol process, and on the PE-2 strain of Saccharomyces cerevisiae, one of the main fermenting yeasts in Brazil. This pointed to the need to know the molecular mechanism that lay behind the cell resistance to this compound. In this study, we examined the factors involved in PHMB-cell interaction and the mechanisms that respond to the damage caused by this interaction. To achieve this, two research strategies were employed: the expression of some genes by RT-qPCR and the analysis of mutant strains. Results Cell Wall integrity (CWI) genes were induced in the PHMB-resistant Saccharomyces cerevisiae strain JP-1, although they are poorly expressed in the PHMB-sensitive Saccharomyces cerevisiae PE2 strain. This suggested that PHMB damages the glucan structure on the yeast cell wall. It was also confirmed by the observed sensitivity of the yeast deletion strains, Δslg1, Δrom2, Δmkk2, Δslt2, Δknr4, Δswi4 and Δswi4, which showed that the protein kinase C (PKC) regulatory mechanism is involved in the response and resistance to PHMB. The sensitivity of the Δhog1 mutant was also observed. Furthermore, the cytotoxicity assay and gene expression analysis showed that the part played by YAP1 and CTT1 genes in cell resistance to PHMB is unrelated to oxidative stress response. Thus, we suggested that Yap1p can play a role in cell wall maintenance by controlling the expression of the CWI genes. Conclusion The PHMB treatment of the yeast cells activates the PKC1/Slt2 (CWI) pathway. In addition, it is suggested that HOG1 and YAP1 can play a role in the regulation of CWI genes. PMID:21854579

  8. Identification of a Saccharomyces cerevisiae glucosidase that hydrolyzes flavonoid glucosides.

    PubMed

    Schmidt, Sabine; Rainieri, Sandra; Witte, Simone; Matern, Ulrich; Martens, Stefan

    2011-03-01

    Baker's yeast (Saccharomyces cerevisiae) whole-cell bioconversions of naringenin 7-O-β-glucoside revealed considerable β-glucosidase activity, which impairs any strategy to generate or modify flavonoid glucosides in yeast transformants. Up to 10 putative glycoside hydrolases annotated in the S. cerevisiae genome database were overexpressed with His tags in yeast cells. Examination of these recombinant, partially purified polypeptides for hydrolytic activity with synthetic chromogenic α- or β-glucosides identified three efficient β-glucosidases (EXG1, SPR1, and YIR007W), which were further assayed with natural flavonoid β-glucoside substrates and product verification by thin-layer chromatography (TLC) or high-performance liquid chromatography (HPLC). Preferential hydrolysis of 7- or 4'-O-glucosides of isoflavones, flavonols, flavones, and flavanones was observed in vitro with all three glucosidases, while anthocyanins were also accepted as substrates. The glucosidase activities of EXG1 and SPR1 were completely abolished by Val168Tyr mutation, which confirmed the relevance of this residue, as reported for other glucosidases. Most importantly, biotransformation experiments with knockout yeast strains revealed that only EXG1 knockout strains lost the capability to hydrolyze flavonoid glucosides.

  9. The Ty1 LTR-retrotransposon of budding yeast, Saccharomyces cerevisiae

    PubMed Central

    Curcio, M. Joan; Lutz, Sheila; Lesage, Pascale

    2015-01-01

    Summary Long-terminal repeat (LTR)-retrotransposons generate a copy of their DNA (cDNA) by reverse transcription of their RNA genome in cytoplasmic nucleocapsids. They are widespread in the eukaryotic kingdom and are the evolutionary progenitors of retroviruses [1]. The Ty1 element of the budding yeast Saccharomyces cerevisiae was the first LTR-retrotransposon demonstrated to mobilize through an RNA intermediate, and not surprisingly, is the best studied. The depth of our knowledge of Ty1 biology stems not only from the predominance of active Ty1 elements in the S. cerevisiae genome but also the ease and breadth of genomic, biochemical and cell biology approaches available to study cellular processes in yeast. This review describes the basic structure of Ty1 and its gene products, the replication cycle, the rapidly expanding compendium of host co-factors known to influence retrotransposition and the nature of Ty1's elaborate symbiosis with its host. Our goal is to illuminate the value of Ty1 as a paradigm to explore the biology of LTR-retrotransposons in multicellular organisms, where the low frequency of retrotransposition events presents a formidable barrier to investigations of retrotransposon biology. PMID:25893143

  10. Flor yeasts of Saccharomyces cerevisiae--their ecology, genetics and metabolism.

    PubMed

    Alexandre, Hervé

    2013-10-15

    The aging of certain white wines is dependent on the presence of yeast strains that develop a biofilm on the wine surface after the alcoholic fermentation. These strains belong to the genus Saccharomyces and are called flor yeasts. These strains possess distinctive characteristics compared with Saccharomyces cerevisiae fermenting strain. The most important one is their capacity to form a biofilm on the air-liquid interface of the wine. The major gene involved in this phenotype is FLO11, however other genes are also involved in velum formation by these yeast and will be detailed. Other striking features presented in this review are their aneuploidy, and their mitochondrial DNA polymorphism which seems to reflect adaptive evolution of the yeast to a stressful environment where acetaldehyde and ethanol are present at elevated concentration. The biofilm assures access to oxygen and therefore permits continued growth on non-fermentable ethanol. This specific metabolism explains the peculiar organoleptic profile of these wines, especially their content in acetaldehyde and sotolon. This review deals with these different specificities of flor yeasts and will also underline the existing gaps regarding these astonishing yeasts. © 2013.

  11. Macromolecular Synthesis During the Germination of Saccharomyces cerevisiae Spores

    PubMed Central

    Rousseau, Paul; Halvorson, Harlyn O.

    1973-01-01

    After the dormancy of Saccharomyces cerevisiae ascospores had been broken, the synthesis of proteins was observed first, followed rapidly by synthesis of ribonucleic acid (RNA) and much later by deoxyribonucleic acid (DNA) synthesis. Phosphoglucomutase activity increased in a periodic (step) fashion, whereas the activity of five other enzymes increased linearly during germination and outgrowth. The rate of synthesis of these enzymes was highest at about the period of DNA replication. The amino acid pools of dormant spores contained high levels of proline, glutamic acid, and histidine. At 2 h after onset of germination, the pools of phenylalanine and methionine had disappeared and the other components had decreased significantly. By 3.5 h, with the exception of proline and cystine, most amino acid pool components had significantly increased. PMID:4570780

  12. Mechanisms and Regulation of Mitotic Recombination in Saccharomyces cerevisiae

    PubMed Central

    Symington, Lorraine S.; Rothstein, Rodney; Lisby, Michael

    2014-01-01

    Homology-dependent exchange of genetic information between DNA molecules has a profound impact on the maintenance of genome integrity by facilitating error-free DNA repair, replication, and chromosome segregation during cell division as well as programmed cell developmental events. This chapter will focus on homologous mitotic recombination in budding yeast Saccharomyces cerevisiae. However, there is an important link between mitotic and meiotic recombination (covered in the forthcoming chapter by Hunter et al. 2015) and many of the functions are evolutionarily conserved. Here we will discuss several models that have been proposed to explain the mechanism of mitotic recombination, the genes and proteins involved in various pathways, the genetic and physical assays used to discover and study these genes, and the roles of many of these proteins inside the cell. PMID:25381364

  13. Direct enzyme assay evidence confirms aldehyde reductase function of Ydr541cp and Ygl039wp from Saccharomyces cerevisiae

    USDA-ARS?s Scientific Manuscript database

    Aldehyde reductase gene ARI1 is a recently characterized member of intermediate subfamily under SDR (short-chain dehydrogenase/reductase) superfamily that revealed mechanisms of in situ detoxification of furfural and HMF for tolerance of Saccharomyces cerevisiae. Uncharacterized open reading frames ...

  14. Phenotypic selection of a wild Saccharomyces cerevisiae strain for simultaneous saccharification and co-fermentation of AFEX pretreated corn stover

    Treesearch

    Mingie Jin; Cory Sarks; Christa Gunawan; Benjamin D. Bice; Shane P. Simonett; Ragothaman Avanasi Narasimhan; Laura B. Willis; Bruce E. Dale; Venkatesh Balan; Trey K. Sato

    2013-01-01

    Simultaneous saccharification and co-fermentation (SSCF) process involves enzymatic hydrolysis of pretreated lignocellulosic biomass and fermentation of glucose and xylose in one bioreactor. The optimal temperatures for enzymatic hydrolysis are higher than the standard fermentation temperature of ethanologenic Saccharomyces cerevisiae. Moreover,...

  15. Dynamic study of yeast species and Saccharomyces cerevisiae strains during the spontaneous fermentations of Muscat blanc in Jingyang, China.

    PubMed

    Wang, Chunxiao; Liu, Yanlin

    2013-04-01

    The evolution of yeast species and Saccharomyces cerevisiae genotypes during spontaneous fermentations of Muscat blanc planted in 1957 in Jingyang region of China was followed in this study. Using a combination of colony morphology on Wallerstein Nutrient (WLN) medium, sequence analysis of the 26S rDNA D1/D2 domain and 5.8S-ITS-RFLP analysis, a total of 686 isolates were identified at the species level. The six species identified were S. cerevisiae, Hanseniaspora uvarum, Hanseniaspora opuntiae, Issatchenkia terricola, Pichia kudriavzevii (Issatchenkia orientalis) and Trichosporon coremiiforme. This is the first report of T. coremiiforme as an inhabitant of grape must. Three new colony morphologies on WLN medium and one new 5.8S-ITS-RFLP profile are described. Species of non-Saccharomyces, predominantly H. opuntiae, were found in early stages of fermentation. Subsequently, S. cerevisiae prevailed followed by large numbers of P. kudriavzevii that dominated at the end of fermentations. Six native genotypes of S. cerevisiae were determined by interdelta sequence analysis. Genotypes III and IV were predominant. As a first step in exploring untapped yeast resources of the region, this study is important for monitoring the yeast ecology in native fermentations and screening indigenous yeasts that will produce wines with regional characteristics. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Widespread Use of Non-productive Alternative Splice Sites in Saccharomyces cerevisiae

    PubMed Central

    Kawashima, Tadashi; Douglass, Stephen; Gabunilas, Jason; Pellegrini, Matteo; Chanfreau, Guillaume F.

    2014-01-01

    Saccharomyces cerevisiae has been used as a model system to investigate the mechanisms of pre-mRNA splicing but only a few examples of alternative splice site usage have been described in this organism. Using RNA-Seq analysis of nonsense-mediated mRNA decay (NMD) mutant strains, we show that many S. cerevisiae intron-containing genes exhibit usage of alternative splice sites, but many transcripts generated by splicing at these sites are non-functional because they introduce premature termination codons, leading to degradation by NMD. Analysis of splicing mutants combined with NMD inactivation revealed the role of specific splicing factors in governing the use of these alternative splice sites and identified novel functions for Prp17p in enhancing the use of branchpoint-proximal upstream 3′ splice sites and for Prp18p in suppressing the usage of a non-canonical AUG 3′-splice site in GCR1. The use of non-productive alternative splice sites can be increased in stress conditions in a promoter-dependent manner, contributing to the down-regulation of genes during stress. These results show that alternative splicing is frequent in S. cerevisiae but masked by RNA degradation and that the use of alternative splice sites in this organism is mostly aimed at controlling transcript levels rather than increasing proteome diversity. PMID:24722551

  17. An energy-saving glutathione production method from low-temperature cooked rice using amylase-expressing Saccharomyces cerevisiae.

    PubMed

    Hara, Kiyotaka Y; Kim, Songhee; Kiriyama, Kentaro; Yoshida, Hideyo; Arai, Shogo; Ishii, Jun; Ogino, Chiaki; Fukuda, Hideki; Kondo, Akihiko

    2012-05-01

    Glutathione is a valuable tripeptide that is widely used in the pharmaceutical, food, and cosmetic industries. Glutathione is industrially produced by fermentation using Saccharomyces cerevisiae. Before the glutathione fermentation process with S. cerevisiae, a glucose extraction process from starchy materials is required. This glucose extraction is usually carried out by converting starchy materials to starch using high-temperature cooking and subsequent hydrolysis by amylases to convert starch to glucose. In this study, to develop an energy-saving glutathione production process by reducing energy consumption during the cooking step, we efficiently produced glutathione from low-temperature cooked rice using amylase-expressing S. cerevisiae. The combination of the amylase-expressing yeast with low-temperature cooking is potentially applicable to a variety of energy-saving bio-production methods of chemicals from starchy bio-resources. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Use of Saccharomyces cerevisiae To Reduce the Bioaccessibility of Mercury from Food.

    PubMed

    Jadán-Piedra, Carlos; Baquedano, Marta; Puig, Sergi; Vélez, Dinoraz; Devesa, Vicenta

    2017-04-05

    Food is the main pathway of exposure to inorganic mercury [Hg(II)] and methylmercury (CH 3 Hg). Intestinal absorption of these mercury species is influenced by their chemical form, the luminal pH, and the composition of the diet. In this regard, strategies have been proposed for reducing mercury absorption using dietary components. This study evaluates the capacity of Saccharomyces cerevisiae to reduce the amount of mercury solubilized after gastrointestinal digestion that is available for intestinal absorption (bioaccessibility). The results show that S. cerevisiae strains reduce mercury bioaccessibility from aqueous solutions of Hg(II) (89 ± 6%) and CH 3 Hg (83 ± 4%), and from mushrooms (19-77%), but not from seafood. The formation of mercury-cysteine or mercury-polypeptide complexes in the bioaccessible fraction may contribute to the reduced effect of yeasts on mercury bioaccessibility from seafood. Our study indicates that budding yeasts could be useful for reducing the extent of intestinal absorption of mercury present in water and some food matrices.

  19. European derived Saccharomyces cerevisiae colonisation of New Zealand vineyards aided by humans

    PubMed Central

    Gayevskiy, Velimir; Lee, Soon

    2016-01-01

    Humans have acted as vectors for species and expanded their ranges since at least the dawn of agriculture. While relatively well characterised for macrofauna and macroflora, the extent and dynamics of human-aided microbial dispersal is poorly described. We studied the role which humans have played in manipulating the distribution of Saccharomyces cerevisiae, one of the world's most important microbes, using whole genome sequencing. We include 52 strains representative of the diversity in New Zealand to the global set of genomes for this species. Phylogenomic approaches show an exclusively European origin of the New Zealand population, with a minimum of 10 founder events mostly taking place over the last 1000 years. Our results show that humans have expanded the range of S. cerevisiae and transported it to New Zealand where it was not previously present, where it has now become established in vineyards, but radiation to native forests appears limited. PMID:27744274

  20. Tributyltin induces cell cycle arrest at G1 phase in the yeast Saccharomyces cerevisiae.

    PubMed

    Sekito, Takayuki; Sugimoto, Naoko; Ishimoto, Masaya; Kawano-Kawada, Miyuki; Akiyama, Koichi; Nishimoto, Sogo; Sugahara, Takuya; Kakinuma, Yoshimi

    2014-04-01

    Tributyltin (TBT) has long been recognized as a major environmental pollutant that can cause significant damage to the cellular functions as well as disruption of endocrine homeostasis. TBT induces apoptosis accompanied by production of reactive oxygen species (ROS) in mammalian and yeast cells. We observed that the budding yeast cells exposed to this compound at low concentrations exhibited cell growth arrest, but not cell death. Flow cytometric analysis of yeast cells without synchronization and morphological assessment of cells synchronized at M phase by nocodazole treatment indicated that TBT-exposed Saccharomyces cerevisiae cells were arrested at G1 phase of the cell cycle. This arrest was recovered by the addition of N-acetylcysteine, suggesting the involvement of ROS production by TBT. This is the first study to evaluate the action of TBT on cell cycle events.

  1. Enhanced production of para-hydroxybenzoic acid by genetically engineered Saccharomyces cerevisiae.

    PubMed

    Averesch, Nils J H; Prima, Alex; Krömer, Jens O

    2017-08-01

    Saccharomyces cerevisiae is a popular organism for metabolic engineering; however, studies aiming at over-production of bio-replacement precursors for the chemical industry often fail to overcome proof-of-concept stage. When intending to show real industrial attractiveness, the challenge is twofold: formation of the target compound must be increased, while minimizing the formation of side and by-products to maximize titer, rate and yield. To tackle these, the metabolism of the organism, as well as the parameters of the process, need to be optimized. Addressing both we show that S. cerevisiae is well-suited for over-production of aromatic compounds, which are valuable in chemical industry and are particularly useful in space technology. Specifically, a strain engineered to accumulate chorismate was optimized for formation of para-hydroxybenzoic acid. Then a fed-batch bioreactor process was developed, which delivered a final titer of 2.9 g/L, a maximum rate of 18.625 mg pHBA /(g CDW  × h) and carbon-yields of up to 3.1 mg pHBA /g glucose .

  2. Saccharomyces cerevisiae gene expression changes during rotating wall vessel suspension culture

    NASA Technical Reports Server (NTRS)

    Johanson, Kelly; Allen, Patricia L.; Lewis, Fawn; Cubano, Luis A.; Hyman, Linda E.; Hammond, Timothy G.

    2002-01-01

    This study utilizes Saccharomyces cerevisiae to study genetic responses to suspension culture. The suspension culture system used in this study is the high-aspect-ratio vessel, one type of the rotating wall vessel, that provides a high rate of gas exchange necessary for rapidly dividing cells. Cells were grown in the high-aspect-ratio vessel, and DNA microarray and metabolic analyses were used to determine the resulting changes in yeast gene expression. A significant number of genes were found to be up- or downregulated by at least twofold as a result of rotational growth. By using Gibbs promoter alignment, clusters of genes were examined for promoter elements mediating these genetic changes. Candidate binding motifs similar to the Rap1p binding site and the stress-responsive element were identified in the promoter regions of differentially regulated genes. This study shows that, as in higher order organisms, S. cerevisiae changes gene expression in response to rotational culture and also provides clues for investigations into the signaling pathways involved in gravitational response.

  3. Improved Acetic Acid Resistance in Saccharomyces cerevisiae by Overexpression of the WHI2 Gene Identified through Inverse Metabolic Engineering

    PubMed Central

    Chen, Yingying; Stabryla, Lisa

    2016-01-01

    Development of acetic acid-resistant Saccharomyces cerevisiae is important for economically viable production of biofuels from lignocellulosic biomass, but the goal remains a critical challenge due to limited information on effective genetic perturbation targets for improving acetic acid resistance in the yeast. This study employed a genomic-library-based inverse metabolic engineering approach to successfully identify a novel gene target, WHI2 (encoding a cytoplasmatic globular scaffold protein), which elicited improved acetic acid resistance in S. cerevisiae. Overexpression of WHI2 significantly improved glucose and/or xylose fermentation under acetic acid stress in engineered yeast. The WHI2-overexpressing strain had 5-times-higher specific ethanol productivity than the control in glucose fermentation with acetic acid. Analysis of the expression of WHI2 gene products (including protein and transcript) determined that acetic acid induced endogenous expression of Whi2 in S. cerevisiae. Meanwhile, the whi2Δ mutant strain had substantially higher susceptibility to acetic acid than the wild type, suggesting the important role of Whi2 in the acetic acid response in S. cerevisiae. Additionally, overexpression of WHI2 and of a cognate phosphatase gene, PSR1, had a synergistic effect in improving acetic acid resistance, suggesting that Whi2 might function in combination with Psr1 to elicit the acetic acid resistance mechanism. These results improve our understanding of the yeast response to acetic acid stress and provide a new strategy to breed acetic acid-resistant yeast strains for renewable biofuel production. PMID:26826231

  4. Fermentation Temperature Modulates Phosphatidylethanolamine and Phosphatidylinositol Levels in the Cell Membrane of Saccharomyces cerevisiae

    PubMed Central

    Henderson, Clark M.; Zeno, Wade F.; Lerno, Larry A.; Longo, Marjorie L.

    2013-01-01

    During alcoholic fermentation, Saccharomyces cerevisiae is exposed to a host of environmental and physiological stresses. Extremes of fermentation temperature have previously been demonstrated to induce fermentation arrest under growth conditions that would otherwise result in complete sugar utilization at “normal” temperatures and nutrient levels. Fermentations were carried out at 15°C, 25°C, and 35°C in a defined high-sugar medium using three Saccharomyces cerevisiae strains with diverse fermentation characteristics. The lipid composition of these strains was analyzed at two fermentation stages, when ethanol levels were low early in stationary phase and in late stationary phase at high ethanol concentrations. Several lipids exhibited dramatic differences in membrane concentration in a temperature-dependent manner. Principal component analysis (PCA) was used as a tool to elucidate correlations between specific lipid species and fermentation temperature for each yeast strain. Fermentations carried out at 35°C exhibited very high concentrations of several phosphatidylinositol species, whereas at 15°C these yeast strains exhibited higher levels of phosphatidylethanolamine and phosphatidylcholine species with medium-chain fatty acids. Furthermore, membrane concentrations of ergosterol were highest in the yeast strain that experienced stuck fermentations at all three temperatures. Fluorescence anisotropy measurements of yeast cell membrane fluidity during fermentation were carried out using the lipophilic fluorophore diphenylhexatriene. These measurements demonstrate that the changes in the lipid composition of these yeast strains across the range of fermentation temperatures used in this study did not significantly affect cell membrane fluidity. However, the results from this study indicate that fermenting S. cerevisiae modulates its membrane lipid composition in a temperature-dependent manner. PMID:23811519

  5. The ecology and evolution of non-domesticated Saccharomyces species.

    PubMed

    Boynton, Primrose J; Greig, Duncan

    2014-12-01

    Yeast researchers need model systems for ecology and evolution, but the model yeast Saccharomyces cerevisiae is not ideal because its evolution has been affected by domestication. Instead, ecologists and evolutionary biologists are focusing on close relatives of S. cerevisiae, the seven species in the genus Saccharomyces. The best-studied Saccharomyces yeast, after S. cerevisiae, is S. paradoxus, an oak tree resident throughout the northern hemisphere. In addition, several more members of the genus Saccharomyces have recently been discovered. Some Saccharomyces species are only found in nature, while others include both wild and domesticated strains. Comparisons between domesticated and wild yeasts have pinpointed hybridization, introgression and high phenotypic diversity as signatures of domestication. But studies of wild Saccharomyces natural history, biogeography and ecology are only beginning. Much remains to be understood about wild yeasts' ecological interactions and life cycles in nature. We encourage researchers to continue to investigate Saccharomyces yeasts in nature, both to place S. cerevisiae biology into its ecological context and to develop the genus Saccharomyces as a model clade for ecology and evolution. © 2014 The Authors. Yeast published by John Wiley & Sons, Ltd.

  6. The ecology and evolution of non-domesticated Saccharomyces species

    PubMed Central

    Boynton, Primrose J; Greig, Duncan

    2014-01-01

    Yeast researchers need model systems for ecology and evolution, but the model yeast Saccharomyces cerevisiae is not ideal because its evolution has been affected by domestication. Instead, ecologists and evolutionary biologists are focusing on close relatives of S. cerevisiae, the seven species in the genus Saccharomyces. The best-studied Saccharomyces yeast, after S. cerevisiae, is S. paradoxus, an oak tree resident throughout the northern hemisphere. In addition, several more members of the genus Saccharomyces have recently been discovered. Some Saccharomyces species are only found in nature, while others include both wild and domesticated strains. Comparisons between domesticated and wild yeasts have pinpointed hybridization, introgression and high phenotypic diversity as signatures of domestication. But studies of wild Saccharomyces natural history, biogeography and ecology are only beginning. Much remains to be understood about wild yeasts' ecological interactions and life cycles in nature. We encourage researchers to continue to investigate Saccharomyces yeasts in nature, both to place S. cerevisiae biology into its ecological context and to develop the genus Saccharomyces as a model clade for ecology and evolution. © 2014 The Authors. Yeast published by John Wiley & Sons Ltd. PMID:25242436

  7. Split luciferase complementation assay for the analysis of G protein-coupled receptor ligand response in Saccharomyces cerevisiae.

    PubMed

    Fukutani, Yosuke; Ishii, Jun; Kondo, Akihiko; Ozawa, Takeaki; Matsunami, Hiroaki; Yohda, Masafumi

    2017-06-01

    The budding yeast Saccharomyces cerevisiae is equipped with G protein-coupled receptors (GPCR). Because the yeast GPCR signaling mechanism is partly similar to that of the mammalian system, S. cerevisiae can be used for a host of mammalian GPCR expression and ligand-mediated activation assays. However, currently available yeast systems require several hours to observe the responses because they depend on the expression of reporter genes. In this study, we attempted to develop a simple GPCR assay system using split luciferase and β-arrestin, which are independent of the endogenous S. cerevisiae GPCR signaling pathways. We applied the split luciferase complementation assay method to S. cerevisiae and found that it can be used to analyze the ligand response of the human somatostatin receptor in S. cerevisiae. On the contrary, the response of the pheromone receptor Ste2 was not observed by the assay. Thus, the split luciferase complementation should be free from the effect of the endogenous GPCR signaling. Biotechnol. Bioeng. 2017;114: 1354-1361. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  8. Enhancement of protein production via the strong DIT1 terminator and two RNA-binding proteins in Saccharomyces cerevisiae.

    PubMed

    Ito, Yoichiro; Kitagawa, Takao; Yamanishi, Mamoru; Katahira, Satoshi; Izawa, Shingo; Irie, Kenji; Furutani-Seiki, Makoto; Matsuyama, Takashi

    2016-11-15

    Post-transcriptional upregulation is an effective way to increase the expression of transgenes and thus maximize the yields of target chemicals from metabolically engineered organisms. Refractory elements in the 3' untranslated region (UTR) that increase mRNA half-life might be available. In Saccharomyces cerevisiae, several terminator regions have shown activity in increasing the production of proteins by upstream coding genes; among these terminators the DIT1 terminator has the highest activity. Here, we found in Saccharomyces cerevisiae that two resident trans-acting RNA-binding proteins (Nab6p and Pap1p) enhance the activity of the DIT1 terminator through the cis element GUUCG/U within the 3'-UTR. These two RNA-binding proteins could upregulate a battery of cell-wall-related genes. Mutagenesis of the DIT1 terminator improved its activity by a maximum of 500% of that of the standard PGK1 terminator. Further understanding and improvement of this system will facilitate inexpensive and stable production of complicated organism-derived drugs worldwide.

  9. p53 death signal is mainly mediated by Nuc1(EndoG) in the yeast Saccharomyces cerevisiae.

    PubMed

    Palermo, Vanessa; Mangiapelo, Eleonora; Piloto, Cristina; Pieri, Luisa; Muscolini, Michela; Tuosto, Loretta; Mazzoni, Cristina

    2013-11-01

    The tumor suppressor p53 plays a central role in the regulation of cellular growth and apoptosis. In the yeast Saccharomyces cerevisiae, the overexpression of the human p53 leads to growth inhibition and apoptotic cell death on minimal medium. In the present work, we show that p53-expressing cells are more susceptible to cell death after an apoptotic stimulus such as H2O2. The analysis of mutants involved in yeast apoptosis-like death suggests that the observed cell death is Yca1 independent and mainly mediated through Nuc1p. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  10. Influence of cultivation procedure for Saccharomyces cerevisiae used as pitching agent in industrial spent sulphite liquor fermentations.

    PubMed

    Johansson, Emma; Brandberg, Tomas; Larsson, Christer

    2011-11-01

    The cell viability and fermentation performance often deteriorate in fermentations of spent sulphite liquor (SSL). This investigation therefore addresses the question of how different cultivation conditions for yeast cells influence their ability to survive and boost the ethanol production capacity in an SSL-based fermentation process. The strains used as pitching agents were an industrially harvested Saccharomyces cerevisiae and commercial dry baker's yeast. This study therefore suggests that exposure to SSL in combination with nutrients, prior to the fermentation step, is crucial for the performance of the yeast. Supplying 0.5 g/l fresh yeast cultivated under appropriate cultivation conditions may increase ethanol concentration more than 200%.

  11. [Characteristics of extracellular invertase of Saccharomyces cerevisiae in Heterologous expression of the suc2 gene in Solarium Tuberosum plants].

    PubMed

    Deriabin, A N; Berdichevets, I N; Burakhanova, E A; Trunova, T I

    2014-01-01

    Some properties and activity of extracellular invertase in the Saccharomyces cerevisiae yeasts encoded by the suc2 gene in heterologous expression were described. It was shown that the target suc2 gene is actively expressed in the genome of the transformed potato plants and S. cerevisiae invertase synthesized by this gene is transported into the apoplast due to the signal peptide of the proteinase II inhibitor. This enzyme is present in the apoplast in a soluble form and absorbed into the cell wall.

  12. Functional Expression and Characterization of Schizosaccharomyces pombe Avt3p as a Vacuolar Amino Acid Exporter in Saccharomyces cerevisiae.

    PubMed

    Chardwiriyapreecha, Soracom; Manabe, Kunio; Iwaki, Tomoko; Kawano-Kawada, Miyuki; Sekito, Takayuki; Lunprom, Siriporn; Akiyama, Koichi; Takegawa, Kaoru; Kakinuma, Yoshimi

    2015-01-01

    In Saccharomyces cerevisiae, Avt3p and Avt4p mediate the extrusion of several amino acids from the vacuolar lumen into the cytosol. SpAvt3p of Schizosaccharomyces pombe, a homologue of these vacuolar amino acid transporters, has been indicated to be involved in spore formation. In this study, we confirmed that GFP-SpAvt3p localized to the vacuolar membrane in S. pombe. The amounts of various amino acids increased significantly in the vacuolar pool of avt3Δ cells, but decreased in that of avt3+-overexpressing avt3Δ cells. These results suggest that SpAvt3p participates in the vacuolar compartmentalization of amino acids in S. pombe. To examine the export activity of SpAvt3p, we expressed the avt3+ gene in S. cerevisiae cells. We found that the heterologously overproduced GFP-SpAvt3p localized to the vacuolar membrane in S. cerevisiae. Using the vacuolar membrane vesicles isolated from avt3+-overexpressing S. cerevisiae cells, we detected the export activities of alanine and tyrosine in an ATP-dependent manner. These activities were inhibited by the addition of a V-ATPase inhibitor, concanamycin A, thereby suggesting that the activity of SpAvt3p is dependent on a proton electrochemical gradient generated by the action of V-ATPase. In addition, the amounts of various amino acids in the vacuolar pools of S. cerevisiae cells were decreased by the overproduction of SpAvt3p, which indicated that SpAvt3p was functional in S. cerevisiae cells. Thus, SpAvt3p is a vacuolar transporter that is involved in the export of amino acids from S. pombe vacuoles.

  13. Oxygen availability and strain combination modulate yeast growth dynamics in mixed culture fermentations of grape must with Starmerella bacillaris and Saccharomyces cerevisiae.

    PubMed

    Englezos, Vasileios; Cravero, Francesco; Torchio, Fabrizio; Rantsiou, Kalliopi; Ortiz-Julien, Anne; Lambri, Milena; Gerbi, Vincenzo; Rolle, Luca; Cocolin, Luca

    2018-02-01

    Starmerella bacillaris (synonym Candida zemplinina) is a non-Saccharomyces yeast that has been proposed as a co-inoculant of selected Saccharomyces cerevisiae strains in mixed culture fermentations to enhance the analytical composition of the wines. In order to acquire further knowledge on the metabolic interactions between these two species, in this study we investigated the impact of oxygen addition and combination of Starm. bacillaris with S. cerevisiae strains on the microbial growth and metabolite production. Fermentations were carried out under two different conditions of oxygen availability. Oxygen availability and strain combination clearly influenced the population dynamics throughout the fermentation. Oxygen concentration increased the survival time of Starm. bacillaris and decreased the growth rate of S. cerevisiae strains in mixed culture fermentations, whereas it did not affect the growth of the latter in pure culture fermentations. This study reveals new knowledge about the influence of oxygen availability on the successional evolution of yeast species during wine fermentation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Ubiquitin regulates TORC1 in yeast Saccharomyces cerevisiae.

    PubMed

    Hu, Kejin; Guo, Shuguang; Yan, Gonghong; Yuan, Wenjie; Zheng, Yin; Jiang, Yu

    2016-04-01

    In the yeast Saccharomyces cerevisiae the TOR complex 1 (TORC1) controls many growth-related cellular processes and is essential for cell growth and proliferation. Macrolide antibiotic rapamycin, in complex with a cytosol protein named FKBP12, specifically inhibits TORC1, causing growth arrest. The FKBP12-rapamycin complex interferes with TORC1 function by binding to the FRB domain of the TOR proteins. In an attempt to understand the role of the FRB domain in TOR function, we identified a single point mutation (Tor2(W2041R) ) in the FRB domain of Tor2 that renders yeast cells rapamycin resistant and temperature sensitive. At the permissive temperature, the Tor2 mutant protein is partially defective for binding with Kog1 and TORC1 is impaired for membrane association. At the restrictive temperature, Kog1 but not the Tor2 mutant protein, is rapidly degraded. Overexpression of ubiquitin stabilizes Kog1 and suppresses the growth defect associated with the tor2 mutant at the nonpremissive temperature. We find that ubiquitin binds non-covalently to Kog1, prevents Kog1 from degradation and stabilizes TORC1. Our data reveal a unique role for ubiquitin in regulation of TORC1 and suggest that Kog1 requires association with the Tor proteins for stabilization. © 2016 John Wiley & Sons Ltd.

  15. Targeted proteome analysis of single-gene deletion strains of Saccharomyces cerevisiae lacking enzymes in the central carbon metabolism.

    PubMed

    Matsuda, Fumio; Kinoshita, Syohei; Nishino, Shunsuke; Tomita, Atsumi; Shimizu, Hiroshi

    2017-01-01

    Central carbon metabolism is controlled by modulating the protein abundance profiles of enzymes that maintain the essential systems in living organisms. In this study, metabolic adaptation mechanisms in the model organism Saccharomyces cerevisiae were investigated by direct determination of enzyme abundance levels in 30 wild type and mutant strains. We performed a targeted proteome analysis using S. cerevisiae strains that lack genes encoding the enzymes responsible for central carbon metabolism. Our analysis revealed that at least 30% of the observed variations in enzyme abundance levels could be explained by global regulatory mechanisms. A enzyme-enzyme co-abundance analysis revealed that the abundances of enzyme proteins involved in the trehalose metabolism and glycolysis changed in a coordinated manner under the control of the transcription factors for global regulation. The remaining variations were derived from local mechanisms such as a mutant-specific increase in the abundances of remote enzymes. The proteome data also suggested that, although the functional compensation of the deficient enzyme was attained by using more resources for protein biosynthesis, available resources for the biosynthesis of the enzymes responsible for central metabolism were not abundant in S. cerevisiae cells. These results showed that global and local regulation of enzyme abundance levels shape central carbon metabolism in S. cerevisiae by using a limited resource for protein biosynthesis.

  16. The introduction of the fungal D-galacturonate pathway enables the consumption of D-galacturonic acid by Saccharomyces cerevisiae.

    PubMed

    Biz, Alessandra; Sugai-Guérios, Maura Harumi; Kuivanen, Joosu; Maaheimo, Hannu; Krieger, Nadia; Mitchell, David Alexander; Richard, Peter

    2016-08-18

    Pectin-rich wastes, such as citrus pulp and sugar beet pulp, are produced in considerable amounts by the juice and sugar industry and could be used as raw materials for biorefineries. One possible process in such biorefineries is the hydrolysis of these wastes and the subsequent production of ethanol. However, the ethanol-producing organism of choice, Saccharomyces cerevisiae, is not able to catabolize D-galacturonic acid, which represents a considerable amount of the sugars in the hydrolysate, namely, 18 % (w/w) from citrus pulp and 16 % (w/w) sugar beet pulp. In the current work, we describe the construction of a strain of S. cerevisiae in which the five genes of the fungal reductive pathway for D-galacturonic acid catabolism were integrated into the yeast chromosomes: gaaA, gaaC and gaaD from Aspergillus niger and lgd1 from Trichoderma reesei, and the recently described D-galacturonic acid transporter protein, gat1, from Neurospora crassa. This strain metabolized D-galacturonic acid in a medium containing D-fructose as co-substrate. This work is the first demonstration of the expression of a functional heterologous pathway for D-galacturonic acid catabolism in Saccharomyces cerevisiae. It is a preliminary step for engineering a yeast strain for the fermentation of pectin-rich substrates to ethanol.

  17. Mutagenic effect of freezing on mitochondrial DNA of Saccharomyces cerevisiae.

    PubMed

    Stoycheva, T; Venkov, P; Tsvetkov, Ts

    2007-06-01

    Although suggested in some studies, the mutagenic effect of freezing has not been proved by induction and isolation of mutants. Using a well-defined genetic model, we supply in this communication evidence for the mutagenic effect of freezing on mitochondrial DNA (mtDNA) of the yeast Saccharomyces cerevisiae. The cooling for 2 h at +4 degrees C, followed by freezing for 1 h at -10 degrees C and 16 h at -20 degrees C resulted in induction of respiratory mutations. The immediate freezing in liquid nitrogen was without mutagenic effect. The study of the stepwise procedure showed that the induction of respiratory mutants takes place during the freezing at -10 and -20 degrees C of cells pre-cooled at +4 degrees C. The genetic crosses of freeze-induced mutants evidenced their mitochondrial rho- origin. The freeze-induced rho- mutants are most likely free of simultaneous nuclear mutations. The extracellular presence of cryoprotectants did not prevent the mutagenic effect of freezing while accumulation of cryoprotectors inside cells completely escaped mtDNA from cryodamage. Although the results obtained favor the notion that the mutagenic effect of freezing on yeast mtDNA is due to formation and growth of intracellular ice crystals, other reasons, such as impairment of mtDNA replication or elevated levels of ROS production are discussed as possible explanations of the mutagenic effect of freezing. It is concluded that: (i) freezing can be used as a method for isolation of mitochondrial mutants in S. cerevisiae and (ii) given the substantial development in cryopreservation of cells and tissues, special precautions should be made to avoid mtDNA damage during the cryopreservation procedures.

  18. Saccharomyces cerevisiae-Derived Mannan Does Not Alter Immune Responses to Aspergillus Allergens.

    PubMed

    Lew, D Betty; LeMessurier, Kim S; Palipane, Maneesha; Lin, Yanyan; Samarasinghe, Amali E

    2018-01-01

    Severe asthma with fungal sensitization predominates in the population suffering from allergic asthma, to which there is no cure. While corticosteroids are the mainstay in current treatment, other means of controlling inflammation may be beneficial. Herein, we hypothesized that mannan from Saccharomyces cerevisiae would dampen the characteristics of fungal allergic asthma by altering the pulmonary immune responses. Using wild-type and transgenic mice expressing the human mannose receptor on smooth muscle cells, we explored the outcome of mannan administration during allergen exposure on the pathogenesis of fungal asthma through measurement of cardinal features of disease such as inflammation, goblet cell number, and airway hyperresponsiveness. Mannan treatment did not alter most hallmarks of allergic airways disease in wild-type mice. Transgenic mice treated with mannan during allergen exposure had an equivalent response to non-mannan-treated allergic mice except for a prominent granulocytic influx into airways and cytokine availability. Our studies suggest no role for mannan as an inflammatory regulator during fungal allergy.

  19. Pathway redundancy and protein essentiality revealed in the Saccharomyces cerevisiae interaction networks

    PubMed Central

    Ulitsky, Igor; Shamir, Ron

    2007-01-01

    The biological interpretation of genetic interactions is a major challenge. Recently, Kelley and Ideker proposed a method to analyze together genetic and physical networks, which explains many of the known genetic interactions as linking different pathways in the physical network. Here, we extend this method and devise novel analytic tools for interpreting genetic interactions in a physical context. Applying these tools on a large-scale Saccharomyces cerevisiae data set, our analysis reveals 140 between-pathway models that explain 3765 genetic interactions, roughly doubling those that were previously explained. Model genes tend to have short mRNA half-lives and many phosphorylation sites, suggesting that their stringent regulation is linked to pathway redundancy. We also identify ‘pivot' proteins that have many physical interactions with both pathways in our models, and show that pivots tend to be essential and highly conserved. Our analysis of models and pivots sheds light on the organization of the cellular machinery as well as on the roles of individual proteins. PMID:17437029

  20. Controlled mixed fermentation at winery scale using Zygotorulaspora florentina and Saccharomyces cerevisiae.

    PubMed

    Lencioni, Livio; Romani, Cristina; Gobbi, Mirko; Comitini, Francesca; Ciani, Maurizio; Domizio, Paola

    2016-10-03

    Over the last few years the use of multi-starter inocula has become an attractive biotechnological practice in the search for wine with high flavour complexity or distinctive characters. This has been possible through exploiting the particular oenological features of some non-Saccharomyces yeast strains, and the effects that derive from their specific interactions with Saccharomyces. In the present study, we evaluated the selected strain Zygotorulaspora florentina (formerly Zygosaccharomyces florentinus) in mixed culture fermentations with Saccharomyces cerevisiae, from the laboratory scale to the winery scale. The scale-up fermentation and substrate composition (i.e., white or red musts) influenced the analytical composition of the mixed fermentation. At the laboratory scale, mixed fermentation with Z. florentina exhibited an enhancement of polysaccharides and 2-phenylethanol content and a reduction of volatile acidity. At the winery scale, different fermentation characteristics of Z. florentina were observed. Using Sangiovese red grape juice, sequential fermentation trials showed a significantly higher concentration of glycerol and esters while the sensorial analysis of the resulting wines showed higher floral notes and lower perception of astringency. To our knowledge, this is the first time that this yeasts association has been evaluated at the winery scale indicating the potential use of this mixed culture in red grape varieties. Copyright © 2016. Published by Elsevier B.V.

  1. Identification and Characterization of a Novel Biotin Biosynthesis Gene in Saccharomyces cerevisiae

    PubMed Central

    Wu, Hong; Ito, Kiyoshi; Shimoi, Hitoshi

    2005-01-01

    Yeast Saccharomyces cerevisiae cells generally cannot synthesize biotin, a vitamin required for many carboxylation reactions. Although sake yeasts, which are used for Japanese sake brewing, are classified as S. cerevisiae, they do not require biotin for their growth. In this study, we identified a novel open reading frame (ORF) in the genome of one strain of sake yeast that we speculated to be involved in biotin synthesis. Homologs of this gene are widely distributed in the genomes of sake yeasts. However, they are not found in many laboratory strains and strains used for wine making and beer brewing. This ORF was named BIO6 because it has 52% identity with BIO3, a biotin biosynthesis gene of a laboratory strain. Further research showed that yeasts without the BIO6 gene are auxotrophic for biotin, whereas yeasts holding the BIO6 gene are prototrophic for biotin. The BIO6 gene was disrupted in strain A364A, which is a laboratory strain with one copy of the BIO6 gene. Although strain A364A is prototrophic for biotin, a BIO6 disrupted mutant was found to be auxotrophic for biotin. The BIO6 disruptant was able to grow in biotin-deficient medium supplemented with 7-keto-8-amino-pelargonic acid (KAPA), while the bio3 disruptant was not able to grow in this medium. These results suggest that Bio6p acts in an unknown step of biotin synthesis before KAPA synthesis. Furthermore, we demonstrated that expression of the BIO6 gene, like that of other biotin synthesis genes, was upregulated by depletion of biotin. We conclude that the BIO6 gene is a novel biotin biosynthesis gene of S. cerevisiae. PMID:16269718

  2. Longevity effect of a polysaccharide from Chlorophytum borivilianum on Caenorhabditis elegans and Saccharomyces cerevisiae

    PubMed Central

    Pannakal, Steve Thomas; Jäger, Sibylle; Duranton, Albert; Tewari, Amit; Saha, Subarna; Radhakrishnan, Aneesha; Roy, Nita; Kuntz, Jean François; Fermas, Soraya; Mellor, Jane; Breton, Lionel

    2017-01-01

    The traditional Indian medicine, Ayurveda, provides insights and practical solutions towards a healthy life style. Rasayana is a branch of Ayurveda known for preserving and promoting health, enhancing the quality of life and delaying the aging process. In the traditional knowledge, the Rasayana herb, Chlorophytum borivilianum (C. borivilanum) is regarded as a general health promoting tonic that delays aging and increases lifespan, cognitive function and physical strength. Aging is a complex and multifactorial physiological phenomenon that manifests itself over a wide range of biological systems, tissues, and functions. Longevity is an obvious marker of physiological aging. Simple model systems such as the single-cell budding yeast Saccharomyces cerevisiae (S. cerevisiae) and the nematode, Caenorhabditis elegans (C. elegans) are widely used to study the aging process and longevity. Here, we show that a polysaccharide fraction obtained from C. borivilianum increases the lifespan of S. cerevisiae and C. elegans, using an automated screening platform (ChronoscreenTM). Chemical analysis of this extract revealed a low molecular weight polysaccharide of 1000 Da, predominantly comprising Glu1→6Glu linkage. This polysaccharide showed significant dose-dependent extension of the median lifespan of S. cerevisiae by up to 41% and of the median lifespan of C. elegans by up to 10%. Taking cue from these results and the traditionally described benefits of Rasayanas on skin rejuvenation, we tested in vitro the polysaccharide for potential skin benefits. In a keratinocyte culture, we observed that this polysaccharide increased cell proliferation significantly, and induced synthesis of hyaluronic acid (HA), a well-known extracellular matrix component. Furthermore, when added to culture medium of human reconstructed epidermis, we observed an enhanced production of epidermal markers, e.g. CD44 and HA that are otherwise diminished in aged skin. Together, these results suggest that in

  3. Saccharomyces cerevisiae-based probiotic as novel anti-fungal and anti-inflammatory agent for therapy of vaginal candidiasis.

    PubMed

    Gabrielli, E; Pericolini, E; Ballet, N; Roselletti, E; Sabbatini, S; Mosci, P; Decherf, A Cayzeele; Pélerin, F; Perito, S; Jüsten, P; Vecchiarelli, A

    2018-02-27

    Previously we demonstrated that the treatment with live Saccharomyces cerevisiae exerts beneficial therapeutic effects against vaginal candidiasis. Here, we address potential mechanisms particularly examining the probiotic capacity to modulate both fungus and host-related factors. We show that the S. cerevisiae-based probiotic markedly affects the expression of virulence traits of Candida albicans such as aspartyl proteinases (SAPs) as well as hyphae-associated proteins Hwp1 and Ece1 in the vaginal cavity. On the host side, the probiotic suppression of the influx of neutrophils caused by the fungus into the vaginas of the mice is likely related to: (1) lower production of interleukin-8; and (2) inhibition of SAPs expression. However, these neutrophils displayed reactive oxygen species hyperproduction and increased killing activity as compared to the neutrophils of placebo-treated mice. There was no evidence of any cytotoxic effect by the probiotic, either when used in vivo on vaginal epithelial cell and organ architecture, or in in vitro in human vaginal epithelium. Inactivated yeast cells did not affect any of the factors above. In summary, the data suggest that the beneficial effect exerted by this S. cerevisiae-based probiotic is the result of its interference with the expression of fungus virulence factors coupled with the modulation of the inflammatory response of the host.

  4. Production of polyunsaturated fatty acids in yeast Saccharomyces cerevisiae and its relation to alkaline pH tolerance.

    PubMed

    Yazawa, Hisashi; Iwahashi, Hitoshi; Kamisaka, Yasushi; Kimura, Kazuyoshi; Uemura, Hiroshi

    2009-03-01

    Saccharomyces cerevisiae produces saturated and monounsaturated fatty acids of 16- and 18-carbon atoms and no polyunsaturated fatty acids (PUFAs) with more than two double bonds. To study the biological significance of PUFAs in yeast, we introduced Kluyveromyces lactis Delta12 fatty acid desaturase (KlFAD2) and omega3 fatty acid desaturase (KlFAD3) genes into S. cerevisiae to produce linoleic and alpha-linolenic acids in S. cerevisiae. The strain producing linoleic and alpha-linolenic acids showed an alkaline pH-tolerant phenotype. DNA microarray analyses showed that the transcription of a set of genes whose expressions are under the repression of Rim101p were downregulated in this strain, suggesting that Rim101p, a transcriptional repressor which governs the ion tolerance, was activated. In line with this activation, the strain also showed elevated resistance to Li(+) and Na(+) ions and to zymolyase, a yeast lytic enzyme preparation containing mainly beta-1,3-glucanase, indicating that the cell wall integrity was also strengthened in this strain. Our findings demonstrate a novel influence of PUFA production on transcriptional control that is likely to play an important role in the early stage of alkaline stress response. The Accession No. for microarray data in the Center for Information Biology Gene Expression database is CBX68.

  5. Effect of supplementing a diet with monensin sodium and Saccharomyces Cerevisiae on reproductive performance of Ghezel ewes.

    PubMed

    Ahmadzadeh, Leila; Hosseinkhani, Ali; Daghigh Kia, Hossein

    2018-01-01

    Effect of supplementing a diet, in an attempt to enhance reproduction, with monensin sodium and Saccharomyces cerevisiae yeast on reproductive performance was investigated during the breeding season using 44 Ghezel ewes (body weight 56.97±7.47kg, age 2-5 years and body condition score (BCS) 2.5) which were allocated randomly in equal numbers to the four dietary treatments as follows: 1) Basal diet plus supplemental feed (450g/ewe/d) plus monensin sodium (30mg/ewe/d) (MS); 2) Basal diet plus supplemental feed (450 g/ewe/d) plus Saccharomyces cerevisiae yeast (4×10 9 CFU/ewe/d) (SC); 3) Basal diet plus supplemental feed (450g/ewe/d) (FG); 4) Basal diet (only grazing on pasture, Control; G). Estrous synchronization of all ewes was done using controlled internal drug release (CIDR) and all ewes were mated with purebred Ghezel rams after CIDR removal. The results indicated that MS and SC treatments with 15 lambs had greater number of lambs than ewes of the other two treatment groups. Ewes in MS group with 50% twining rate had the greatest value followed by the FG, SC and G treatment groups (P<0.05). The lambs from ewes in MS and SC groups were heavier in weight than those in FG and G treatments (P<0.01). Blood sample analysis provided evidence that ewes in MS and SC groups had greater concentrations of 17β-estradiol (E2), progesterone (P4), blood urea nitrogen (P<0.05), insulin, glucose, cholesterol and total protein (P<0.01) than ewes of the other groups. These results indicated that using a diet for enhancing reproduction, including monensin sodium and Saccharomyces cerevisiae yeast in the breeding season could have beneficial effects on reproductive performance of Ghezel ewes. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Effects of supplementing a Saccharomyces cerevisiae fermentation product in sow diets on performance of sows and nursing piglets

    USDA-ARS?s Scientific Manuscript database

    Forty-two sows (Camborough-22, PIC) were used to determine the effects of supplementing a Saccharomyces cerevisiae fermentation product (SCFP; Diamond V Original XPC) in gestation and lactation diets on performance of sows and their progeny. On 5 d before breeding, sows were allotted to 2 dietary tr...

  7. Hxt-Carrier-Mediated Glucose Efflux upon Exposure of Saccharomyces cerevisiae to Excess Maltose

    PubMed Central

    Jansen, Mickel L. A.; De Winde, Johannes H.; Pronk, Jack T.

    2002-01-01

    When wild-type Saccharomyces cerevisiae strains pregrown in maltose-limited chemostat cultures were exposed to excess maltose, release of glucose into the external medium was observed. Control experiments confirmed that glucose release was not caused by cell lysis or extracellular maltose hydrolysis. To test the hypothesis that glucose efflux involved plasma membrane glucose transporters, experiments were performed with an S. cerevisiae strain in which all members of the hexose transporter (HXT) gene family had been eliminated and with an isogenic reference strain. Glucose efflux was virtually eliminated in the hexose-transport-deficient strain. This constitutes experimental proof that Hxt transporters facilitate export of glucose from S. cerevisiae cells. After exposure of the hexose-transport-deficient strain to excess maltose, an increase in the intracellular glucose level was observed, while the concentrations of glucose 6-phosphate and ATP remained relatively low. These results demonstrate that glucose efflux can occur as a result of uncoordinated expression of the initial steps of maltose metabolism and the subsequent reactions in glucose dissimilation. This is a relevant phenomenon for selection of maltose-constitutive strains for baking and brewing. PMID:12200274

  8. Increased ethanol production by deletion of HAP4 in recombinant xylose-assimilating Saccharomyces cerevisiae.

    PubMed

    Matsushika, Akinori; Hoshino, Tamotsu

    2015-12-01

    The Saccharomyces cerevisiae HAP4 gene encodes a transcription activator that plays a key role in controlling the expression of genes involved in mitochondrial respiration and reductive pathways. This work examines the effect of knockout of the HAP4 gene on aerobic ethanol production in a xylose-utilizing S. cerevisiae strain. A hap4-deleted recombinant yeast strain (B42-DHAP4) showed increased maximum concentration, production rate, and yield of ethanol compared with the reference strain MA-B42, irrespective of cultivation medium (glucose, xylose, or glucose/xylose mixtures). Notably, B42-DHAP4 was capable of producing ethanol from xylose as the sole carbon source under aerobic conditions, whereas no ethanol was produced by MA-B42. Moreover, the rate of ethanol production and ethanol yield (0.44 g/g) from the detoxified hydrolysate of wood chips was markedly improved in B42-DHAP4 compared to MA-B42. Thus, the results of this study support the view that deleting HAP4 in xylose-utilizing S. cerevisiae strains represents a useful strategy in ethanol production processes.

  9. ATLAS: An advanced PCR-method for routine visualization of telomere length in Saccharomyces cerevisiae.

    PubMed

    Zubko, Elena I; Shackleton, Jennifer L; Zubko, Mikhajlo K

    2016-12-01

    Measuring telomere length is essential in telomere biology. Southern blot hybridization is the predominant method for measuring telomere length in the genetic model Saccharomyces cerevisiae. We have further developed and refined a telomere PCR approach, which was rarely used previously (mainly in specific telomeric projects), into a robust method allowing direct visualisation of telomere length differences in routine experiments with S. cerevisiae, and showing a strong correlation of results with data obtained by Southern blot hybridization. In this expanded method denoted as ATLAS (A-dvanced T-elomere L-ength A-nalysis in S. cerevisiae), we have introduced: 1) set of new primers annealing with high specificity to telomeric regions on five different chromosomes; 2) new approach for designing reverse telomere primers that is based on the ligation of an adaptor of a fixed size to telomeric ends. ATLAS can be used at the scale of individual assays and high-throughput approaches. This simple, time/cost-effective and reproducible methodology will complement Southern blot hybridization and facilitate further progress in telomere research. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Fermentation of Saccharomyces cerevisiae - Combining kinetic modeling and optimization techniques points out avenues to effective process design.

    PubMed

    Scheiblauer, Johannes; Scheiner, Stefan; Joksch, Martin; Kavsek, Barbara

    2018-09-14

    A combined experimental/theoretical approach is presented, for improving the predictability of Saccharomyces cerevisiae fermentations. In particular, a mathematical model was developed explicitly taking into account the main mechanisms of the fermentation process, allowing for continuous computation of key process variables, including the biomass concentration and the respiratory quotient (RQ). For model calibration and experimental validation, batch and fed-batch fermentations were carried out. Comparison of the model-predicted biomass concentrations and RQ developments with the corresponding experimentally recorded values shows a remarkably good agreement for both batch and fed-batch processes, confirming the adequacy of the model. Furthermore, sensitivity studies were performed, in order to identify model parameters whose variations have significant effects on the model predictions: our model responds with significant sensitivity to the variations of only six parameters. These studies provide a valuable basis for model reduction, as also demonstrated in this paper. Finally, optimization-based parametric studies demonstrate how our model can be utilized for improving the efficiency of Saccharomyces cerevisiae fermentations. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Saccharomyces and non-Saccharomyces Competition during Microvinification under Different Sugar and Nitrogen Conditions

    PubMed Central

    Lleixà, Jessica; Manzano, Maria; Mas, Albert; Portillo, María del C.

    2016-01-01

    The inoculation of wines with autochthonous yeast allows obtaining complex wines with a peculiar microbial footprint characteristic from a wine region. Mixed inoculation of non-Saccharomyces yeasts and S. cerevisiae is of interest for the wine industry for technological and sensory reasons. However, the interactions between these yeasts are not well understood, especially those regarding the availability of nutrients. The aim of the present study was to analyze the effect of nitrogen and sugar concentration on the evolution of mixed yeast populations on controlled laboratory-scale fermentations monitored by density, plate culturing, PCR-DGGE and sugar and nitrogen consumption. Furthermore, the effect of the time of inoculation of Saccharomyces cerevisiae respect the initial co-inoculation of three non-Saccharomyces yeasts was evaluated over the evolution of fermentation. Our results have shown that S. cerevisiae inoculation during the first 48 h conferred a stabilizing effect over the fermentations with non-Saccharomyces strains tested and, generally, reduced yeast diversity at the end of the fermentation. On the other hand, nitrogen limitation increased the time of fermentation and also the proportion of non-Saccharomyces yeasts at mid and final fermentation. High sugar concentration resulted in different proportions of the inoculated yeast depending on the time of S. cerevisiae inoculation. This work emphasizes the importance of the concentration of nutrients on the evolution of mixed fermentations and points to the optimal conditions for a stable fermentation in which the inoculated yeasts survived until the end. PMID:27994585

  12. Analysis of Polygenic Mutants Suggests a Role for Mediator in Regulating Transcriptional Activation Distance in Saccharomyces cerevisiae.

    PubMed

    Reavey, Caitlin T; Hickman, Mark J; Dobi, Krista C; Botstein, David; Winston, Fred

    2015-10-01

    Studies of natural populations of many organisms have shown that traits are often complex, caused by contributions of mutations in multiple genes. In contrast, genetic studies in the laboratory primarily focus on studying the phenotypes caused by mutations in a single gene. However, the single mutation approach may be limited with respect to the breadth and degree of new phenotypes that can be found. We have taken the approach of isolating complex, or polygenic mutants in the lab to study the regulation of transcriptional activation distance in yeast. While most aspects of eukaryotic transcription are conserved from yeast to human, transcriptional activation distance is not. In Saccharomyces cerevisiae, the upstream activating sequence (UAS) is generally found within 450 base pairs of the transcription start site (TSS) and when the UAS is moved too far away, activation no longer occurs. In contrast, metazoan enhancers can activate from as far as several hundred kilobases from the TSS. Previously, we identified single mutations that allow transcription activation to occur at a greater-than-normal distance from the GAL1 UAS. As the single mutant phenotypes were weak, we have now isolated polygenic mutants that possess strong long-distance phenotypes. By identification of the causative mutations we have accounted for most of the heritability of the phenotype in each strain and have provided evidence that the Mediator coactivator complex plays both positive and negative roles in the regulation of transcription activation distance. Copyright © 2015 by the Genetics Society of America.

  13. Metabolic engineering of Saccharomyces cerevisiae: a key cell factory platform for future biorefineries.

    PubMed

    Hong, Kuk-Ki; Nielsen, Jens

    2012-08-01

    Metabolic engineering is the enabling science of development of efficient cell factories for the production of fuels, chemicals, pharmaceuticals, and food ingredients through microbial fermentations. The yeast Saccharomyces cerevisiae is a key cell factory already used for the production of a wide range of industrial products, and here we review ongoing work, particularly in industry, on using this organism for the production of butanol, which can be used as biofuel, and isoprenoids, which can find a wide range of applications including as pharmaceuticals and as biodiesel. We also look into how engineering of yeast can lead to improved uptake of sugars that are present in biomass hydrolyzates, and hereby allow for utilization of biomass as feedstock in the production of fuels and chemicals employing S. cerevisiae. Finally, we discuss the perspectives of how technologies from systems biology and synthetic biology can be used to advance metabolic engineering of yeast.

  14. Budding yeast for budding geneticists: a primer on the Saccharomyces cerevisiae model system.

    PubMed

    Duina, Andrea A; Miller, Mary E; Keeney, Jill B

    2014-05-01

    The budding yeast Saccharomyces cerevisiae is a powerful model organism for studying fundamental aspects of eukaryotic cell biology. This Primer article presents a brief historical perspective on the emergence of this organism as a premier experimental system over the course of the past century. An overview of the central features of the S. cerevisiae genome, including the nature of its genetic elements and general organization, is also provided. Some of the most common experimental tools and resources available to yeast geneticists are presented in a way designed to engage and challenge undergraduate and graduate students eager to learn more about the experimental amenability of budding yeast. Finally, a discussion of several major discoveries derived from yeast studies highlights the far-reaching impact that the yeast system has had and will continue to have on our understanding of a variety of cellular processes relevant to all eukaryotes, including humans.

  15. Budding Yeast for Budding Geneticists: A Primer on the Saccharomyces cerevisiae Model System

    PubMed Central

    Duina, Andrea A.; Miller, Mary E.; Keeney, Jill B.

    2014-01-01

    The budding yeast Saccharomyces cerevisiae is a powerful model organism for studying fundamental aspects of eukaryotic cell biology. This Primer article presents a brief historical perspective on the emergence of this organism as a premier experimental system over the course of the past century. An overview of the central features of the S. cerevisiae genome, including the nature of its genetic elements and general organization, is also provided. Some of the most common experimental tools and resources available to yeast geneticists are presented in a way designed to engage and challenge undergraduate and graduate students eager to learn more about the experimental amenability of budding yeast. Finally, a discussion of several major discoveries derived from yeast studies highlights the far-reaching impact that the yeast system has had and will continue to have on our understanding of a variety of cellular processes relevant to all eukaryotes, including humans. PMID:24807111

  16. Aspergillus oryzae–Saccharomyces cerevisiae Consortium Allows Bio-Hybrid Fuel Cell to Run on Complex Carbohydrates

    PubMed Central

    Jahnke, Justin P.; Hoyt, Thomas; LeFors, Hannah M.; Sumner, James J.; Mackie, David M.

    2016-01-01

    Consortia of Aspergillus oryzae and Saccharomyces cerevisiae are examined for their abilities to turn complex carbohydrates into ethanol. To understand the interactions between microorganisms in consortia, Fourier-transform infrared spectroscopy is used to follow the concentrations of various metabolites such as sugars (e.g., glucose, maltose), longer chain carbohydrates, and ethanol to optimize consortia conditions for the production of ethanol. It is shown that with proper design A. oryzae can digest food waste simulants into soluble sugars that S. cerevisiae can ferment into ethanol. Depending on the substrate and conditions used, concentrations of 13% ethanol were achieved in 10 days. It is further shown that a direct alcohol fuel cell (FC) can be coupled with these A. oryzae-enabled S. cerevisiae fermentations using a reverse osmosis membrane. This “bio-hybrid FC” continually extracted ethanol from an ongoing consortium, enhancing ethanol production and allowing the bio-hybrid FC to run for at least one week. Obtained bio-hybrid FC currents were comparable to those from pure ethanol—water mixtures, using the same FC. The A. oryzae–S. cerevisiae consortium, coupled to a bio-hybrid FC, converted food waste simulants into electricity without any pre- or post-processing. PMID:27681904

  17. Aspergillus oryzae-Saccharomyces cerevisiae Consortium Allows Bio-Hybrid Fuel Cell to Run on Complex Carbohydrates.

    PubMed

    Jahnke, Justin P; Hoyt, Thomas; LeFors, Hannah M; Sumner, James J; Mackie, David M

    2016-02-04

    Consortia of Aspergillus oryzae and Saccharomyces cerevisiae are examined for their abilities to turn complex carbohydrates into ethanol. To understand the interactions between microorganisms in consortia, Fourier-transform infrared spectroscopy is used to follow the concentrations of various metabolites such as sugars (e.g., glucose, maltose), longer chain carbohydrates, and ethanol to optimize consortia conditions for the production of ethanol. It is shown that with proper design A. oryzae can digest food waste simulants into soluble sugars that S. cerevisiae can ferment into ethanol. Depending on the substrate and conditions used, concentrations of 13% ethanol were achieved in 10 days. It is further shown that a direct alcohol fuel cell (FC) can be coupled with these A. oryzae-enabled S. cerevisiae fermentations using a reverse osmosis membrane. This "bio-hybrid FC" continually extracted ethanol from an ongoing consortium, enhancing ethanol production and allowing the bio-hybrid FC to run for at least one week. Obtained bio-hybrid FC currents were comparable to those from pure ethanol-water mixtures, using the same FC. The A. oryzae-S. cerevisiae consortium, coupled to a bio-hybrid FC, converted food waste simulants into electricity without any pre- or post-processing.

  18. Thermosensitivity of a barosensitive Saccharomyces cerevisiae mutant obtained by UV mutagenesis

    NASA Astrophysics Data System (ADS)

    Shigematsu, Toru; Nomura, Kazuki; Nasuhara, Yusuke; Ikarashi, Kenta; Nagai, Gen; Hirayama, Masao; Hayashi, Mayumi; Ueno, Shigeaki; Fujii, Tomoyuki

    2010-12-01

    Using UV mutagenesis, a high pressure (HP)-sensitive (barosensitive) mutant of Saccharomyces cerevisiae was obtained. The mutant strain a924E1 showed a significant loss of viability at HP levels of 175 to 250 MPa at 20 °C compared with the parent strain. This strain also showed a significant loss of viability following heat treatment at 50-58 °C at 0.1 MPa. These results showed that the mutation caused a significant thermosensitivity as well as barosensitivity. The activation volume and activation energy values for the inactivation of strain a924E1 were equivalent to those of the parent strain. This suggested that the mechanism for the HP and thermal inactivation reaction of strain a924E1 was basically the same as that of the parent strain. Strain a924E1 showed no deficiency in growth and fermentation ability as well as auxotrophic property. Although the identification of the genetic sites of mutation introduced is underway, these phenotypes are favorable for the application of HP treatment and heat-assisted HP treatment on fermentation control.

  19. Repair of Oxidative DNA Damage in Saccharomyces cerevisiae.

    PubMed

    Chalissery, Jisha; Jalal, Deena; Al-Natour, Zeina; Hassan, Ahmed H

    2017-03-01

    Malfunction of enzymes that detoxify reactive oxygen species leads to oxidative attack on biomolecules including DNA and consequently activates various DNA repair pathways. The nature of DNA damage and the cell cycle stage at which DNA damage occurs determine the appropriate repair pathway to rectify the damage. Oxidized DNA bases are primarily repaired by base excision repair and nucleotide incision repair. Nucleotide excision repair acts on lesions that distort DNA helix, mismatch repair on mispaired bases, and homologous recombination and non-homologous end joining on double stranded breaks. Post-replication repair that overcomes replication blocks caused by DNA damage also plays a crucial role in protecting the cell from the deleterious effects of oxidative DNA damage. Mitochondrial DNA is also prone to oxidative damage and is efficiently repaired by the cellular DNA repair machinery. In this review, we discuss the DNA repair pathways in relation to the nature of oxidative DNA damage in Saccharomyces cerevisiae. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Catheter-related Saccharomyces cerevisiae Fungemia Following Saccharomyces boulardii Probiotic Treatment: In a child in intensive care unit and review of the literature.

    PubMed

    Atıcı, Serkan; Soysal, Ahmet; Karadeniz Cerit, Kıvılcım; Yılmaz, Şerife; Aksu, Burak; Kıyan, Gürsu; Bakır, Mustafa

    2017-03-01

    Although Saccharomyces boulardii is usually a non-pathogenic fungus, in rare occasions it can cause invasive infection in children. We present the case of an 8-year-old patient in pediatric surgical intensive care unit who developed S. cerevisiae fungemia following probiotic treatment containing S. boulardii . Caspofungin was not effective in this case and he was treated with amphotericin B. We want to emphasize that physicians should be careful about probiotic usage in critically ill patients.

  1. Polyphosphatase PPN1 of Saccharomyces cerevisiae: Switching of Exopolyphosphatase and Endopolyphosphatase Activities

    PubMed Central

    Andreeva, Nadezhda; Trilisenko, Ludmila; Eldarov, Mikhail; Kulakovskaya, Tatiana

    2015-01-01

    The polyphosphatase PPN1 of Saccharomyces cerevisiae shows an exopolyphosphatase activity splitting phosphate from chain end and an endopolyphosphatase activity fragmenting high molecular inorganic polyphosphates into shorter polymers. We revealed the compounds switching these activities of PPN1. Phosphate release and fragmentation of high molecular polyphosphate prevailed in the presence of Co2+ and Mg2+, respectively. Phosphate release and polyphosphate chain shortening in the presence of Co2+ were inhibited by ADP but not affected by ATP and argininе. The polyphosphate chain shortening in the presence of Mg2+ was activated by ADP and arginine but inhibited by ATP. PMID:25742176

  2. Saccharomyces cerevisiae biofilm tolerance towards systemic antifungals depends on growth phase.

    PubMed

    Bojsen, Rasmus; Regenberg, Birgitte; Folkesson, Anders

    2014-12-04

    Biofilm-forming Candida species cause infections that can be difficult to eradicate, possibly because of antifungal drug tolerance mechanisms specific to biofilms. In spite of decades of research, the connection between biofilm and drug tolerance is not fully understood. We used Saccharomyces cerevisiae as a model for drug susceptibility of yeast biofilms. Confocal laser scanning microscopy showed that S. cerevisiae and C. glabrata form similarly structured biofilms and that the viable cell numbers were significantly reduced by treatment of mature biofilms with amphotericin B but not voriconazole, flucytosine, or caspofungin. We showed that metabolic activity in yeast biofilm cells decreased with time, as visualized by FUN-1 staining, and mature, 48-hour biofilms contained cells with slow metabolism and limited growth. Time-kill studies showed that in exponentially growing planktonic cells, voriconazole had limited antifungal activity, flucytosine was fungistatic, caspofungin and amphotericin B were fungicidal. In growth-arrested cells, only amphotericin B had antifungal activity. Confocal microscopy and colony count viability assays revealed that the response of growing biofilms to antifungal drugs was similar to the response of exponentially growing planktonic cells. The response in mature biofilm was similar to that of non-growing planktonic cells. These results confirmed the importance of growth phase on drug efficacy. We showed that in vitro susceptibility to antifungal drugs was independent of biofilm or planktonic growth mode. Instead, drug tolerance was a consequence of growth arrest achievable by both planktonic and biofilm populations. Our results suggest that efficient strategies for treatment of yeast biofilm might be developed by targeting of non-dividing cells.

  3. Intracellular metabolite profiling of Saccharomyces cerevisiae evolved under furfural.

    PubMed

    Jung, Young Hoon; Kim, Sooah; Yang, Jungwoo; Seo, Jin-Ho; Kim, Kyoung Heon

    2017-03-01

    Furfural, one of the most common inhibitors in pre-treatment hydrolysates, reduces the cell growth and ethanol production of yeast. Evolutionary engineering has been used as a selection scheme to obtain yeast strains that exhibit furfural tolerance. However, the response of Saccharomyces cerevisiae to furfural at the metabolite level during evolution remains unknown. In this study, evolutionary engineering and metabolomic analyses were applied to determine the effects of furfural on yeasts and their metabolic response to continuous exposure to furfural. After 50 serial transfers of cultures in the presence of furfural, the evolved strains acquired the ability to stably manage its physiological status under the furfural stress. A total of 98 metabolites were identified, and their abundance profiles implied that yeast metabolism was globally regulated. Under the furfural stress, stress-protective molecules and cofactor-related mechanisms were mainly induced in the parental strain. However, during evolution under the furfural stress, S. cerevisiae underwent global metabolic allocations to quickly overcome the stress, particularly by maintaining higher levels of metabolites related to energy generation, cofactor regeneration and recovery from cellular damage. Mapping the mechanisms of furfural tolerance conferred by evolutionary engineering in the present study will be led to rational design of metabolically engineered yeasts. © 2016 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  4. Post-zygotic sterility and cytonuclear compatibility limits in S. cerevisiae xenomitochondrial cybrids

    PubMed Central

    Špírek, Mário; Poláková, Silvia; Jatzová, Katarína; Sulo, Pavol

    2015-01-01

    Nucleo-mitochondrial interactions, particularly those determining the primary divergence of biological species, can be studied by means of xenomitochondrial cybrids, which are cells where the original mitochondria are substituted by their counterparts from related species. Saccharomyces cerevisiae cybrids are prepared simply by the mating of the ρ0 strain with impaired karyogamy and germinating spores from other Saccharomyces species and fall into three categories. Cybrids with compatible mitochondrial DNA (mtDNA) from Saccharomyces paradoxus CBS 432 and Saccharomyces cariocanus CBS 7994 are metabolically and genetically similar to cybrids containing mtDNA from various S. cerevisiae. Cybrids with mtDNA from other S. paradoxus strains, S. cariocanus, Saccharomyces kudriavzevii, and Saccharomyces mikatae require a period of adaptation to establish efficient oxidative phosphorylation. They exhibit a temperature-sensitive phenotype, slower growth rate on a non-fermentable carbon source and a long lag phase after the shift from glucose. Their decreased respiration capacity and reduced cytochrome aa3 content is associated with the inefficient splicing of cox1I3β, the intron found in all Saccharomyces species but not in S. cerevisiae. The splicing defect is compensated in cybrids by nuclear gain-of-function and can be alternatively suppressed by overexpression of MRP13 gene for mitochondrial ribosomal protein or the MRS2, MRS3, and MRS4 genes involved in intron splicing. S. cerevisiae with Saccharomyces bayanus mtDNA is unable to respire and the growth on ethanol–glycerol can be restored only after mating to some mit− strains. The nucleo-mitochondrial compatibility limit of S. cerevisiae and other Saccharomyces was set between S. kudriavzevii and S. bayanus at the divergence from S. cerevisiae about 15 MYA. The MRS1-cox1 S. cerevisiae/S. paradoxus cytonuclear Dobzhansky–Muller pair has a neglible impact on the separation of species since its imperfection is

  5. Engineered Saccharomyces cerevisiae capable of simultaneous cellobiose and xylose fermentation

    PubMed Central

    Ha, Suk-Jin; Galazka, Jonathan M.; Rin Kim, Soo; Choi, Jin-Ho; Yang, Xiaomin; Seo, Jin-Ho; Louise Glass, N.; Cate, Jamie H. D.; Jin, Yong-Su

    2011-01-01

    The use of plant biomass for biofuel production will require efficient utilization of the sugars in lignocellulose, primarily glucose and xylose. However, strains of Saccharomyces cerevisiae presently used in bioethanol production ferment glucose but not xylose. Yeasts engineered to ferment xylose do so slowly, and cannot utilize xylose until glucose is completely consumed. To overcome these bottlenecks, we engineered yeasts to coferment mixtures of xylose and cellobiose. In these yeast strains, hydrolysis of cellobiose takes place inside yeast cells through the action of an intracellular β-glucosidase following import by a high-affinity cellodextrin transporter. Intracellular hydrolysis of cellobiose minimizes glucose repression of xylose fermentation allowing coconsumption of cellobiose and xylose. The resulting yeast strains, cofermented cellobiose and xylose simultaneously and exhibited improved ethanol yield when compared to fermentation with either cellobiose or xylose as sole carbon sources. We also observed improved yields and productivities from cofermentation experiments performed with simulated cellulosic hydrolyzates, suggesting this is a promising cofermentation strategy for cellulosic biofuel production. The successful integration of cellobiose and xylose fermentation pathways in yeast is a critical step towards enabling economic biofuel production. PMID:21187422

  6. Global gene response in Saccharomyces cerevisiae exposed to silver nanoparticles.

    PubMed

    Niazi, Javed H; Sang, Byoung-In; Kim, Yeon Seok; Gu, Man Bock

    2011-08-01

    Silver nanoparticles (AgNPs), exhibiting a broad size range and morphologies with highly reactive facets, which are widely applicable in real-life but not fully verified for biosafety and ecotoxicity, were subjected to report transcriptome profile in yeast Saccharomyces cerevisiae. A large number of genes accounted for ∼3% and ∼5% of the genome affected by AgNPs and Ag-ions, respectively. Principal component and cluster analysis suggest that the different physical forms of Ag were the major cause in differential expression profile. Among 90 genes affected by both AgNPs and Ag-ions, metalloprotein mediating high resistance to copper (CUP1-1 and CUP1-2) were strongly induced by AgNPs (∼45-folds) and Ag-ions (∼22-folds), respectively. A total of 17 genes, responsive to chemical stimuli, stress, and transport processes, were differentially induced by AgNPs. The differential expression was also seen with Ag-ions that affected 73 up- and 161 down-regulating genes, and most of these were involved in ion transport and homeostasis. This study provides new information on the knowledge for impact of nanoparticles on living microorganisms that can be extended to other nanoparticles.

  7. Relationship of trehalose accumulation with ethanol fermentation in industrial Saccharomyces cerevisiae yeast strains.

    PubMed

    Wang, Pin-Mei; Zheng, Dao-Qiong; Chi, Xiao-Qin; Li, Ou; Qian, Chao-Dong; Liu, Tian-Zhe; Zhang, Xiao-Yang; Du, Feng-Guang; Sun, Pei-Yong; Qu, Ai-Min; Wu, Xue-Chang

    2014-01-01

    The protective effect and the mechanisms of trehalose accumulation in industrial Saccharomyces cerevisiae strains were investigated during ethanol fermentation. The engineered strains with more intercellular trehalose achieved significantly higher fermentation rates and ethanol yields than their wild strain ZS during very high gravity (VHG) fermentation, while their performances were not different during regular fermentation. The VHG fermentation performances of these strains were consistent with their growth capacity under osmotic stress and ethanol stress, the key stress factors during VHG fermentation. These results suggest that trehalose accumulation is more important for VHG fermentation of industrial yeast strains than regular one. The differences in membrane integrity and antioxidative capacity of these strains indicated the possible mechanisms of trehalose as a protectant under VHG condition. Therefore, trehalose metabolic engineering may be a useful strategy for improving the VHG fermentation performance of industrial yeast strains. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. The genetic structure of fermentative vineyard-associated Saccharomyces cerevisiae populations revealed by microsatellite analysis.

    PubMed

    Schuller, Dorit; Casal, Margarida

    2007-02-01

    From the analysis of six polymorphic microsatellite loci performed in 361 Saccharomyces cerevisiae isolates, 93 alleles were identified, 52 of them being described for the first time. All these isolates have a distinct mtDNA RFLP pattern. They are derived from a pool of 1620 isolates obtained from spontaneous fermentations of grapes collected in three vineyards of the Vinho Verde Region in Portugal, during the 2001-2003 harvest seasons. For all loci analyzed, observed heterozygosity was 3-4 times lower than the expected value supposing a Hardy-Weinberg equilibrium (random mating and no evolutionary mechanisms acting), indicating a clonal structure and strong populational substructuring. Genetic differences among S. cerevisiae populations were apparent mainly from gradations in allele frequencies rather than from distinctive "diagnostic" genotypes, and the accumulation of small allele-frequency differences across six loci allowed the identification of population structures. Genetic differentiation in the same vineyard in consecutive years was of the same order of magnitude as the differences verified among the different vineyards. Correlation of genetic differentiation with the distance between sampling points within a vineyard suggested a pattern of isolation-by-distance, where genetic divergence in a vineyard increased with size. The continuous use of commercial yeasts has a limited influence on the autochthonous fermentative yeast population collected from grapes and may just slightly change populational structures of strains isolated from sites very close to the winery where they have been used. The present work is the first large-scale approach using microsatellite typing allowing a very fine resolution of indigenous S. cerevisiae populations isolated from vineyards.

  9. Overexpression of NADH-dependent fumarate reductase improves D-xylose fermentation in recombinant Saccharomyces cerevisiae.

    PubMed

    Salusjärvi, Laura; Kaunisto, Sanna; Holmström, Sami; Vehkomäki, Maija-Leena; Koivuranta, Kari; Pitkänen, Juha-Pekka; Ruohonen, Laura

    2013-12-01

    Deviation from optimal levels and ratios of redox cofactors NAD(H) and NADP(H) is common when microbes are metabolically engineered. The resulting redox imbalance often reduces the rate of substrate utilization as well as biomass and product formation. An example is the metabolism of D-xylose by recombinant Saccharomyces cerevisiae strains expressing xylose reductase and xylitol dehydrogenase encoding genes from Scheffersomyces stipitis. This pathway requires both NADPH and NAD(+). The effect of overexpressing the glycosomal NADH-dependent fumarate reductase (FRD) of Trypanosoma brucei in D-xylose-utilizing S. cerevisiae alone and together with an endogenous, cytosol directed NADH-kinase (POS5Δ17) was studied as one possible solution to overcome this imbalance. Expression of FRD and FRD + POS5Δ17 resulted in 60 and 23 % increase in ethanol yield, respectively, on D-xylose under anaerobic conditions. At the same time, xylitol yield decreased in the FRD strain suggesting an improvement in redox balance. We show that fumarate reductase of T. brucei can provide an important source of NAD(+) in yeast under anaerobic conditions, and can be useful for metabolic engineering strategies where the redox cofactors need to be balanced. The effects of FRD and NADH-kinase on aerobic and anaerobic D-xylose and D-glucose metabolism are discussed.

  10. Opuntia ficus-indica cladodes as feedstock for ethanol production by Kluyveromyces marxianus and Saccharomyces cerevisiae.

    PubMed

    Kuloyo, Olukayode O; du Preez, James C; García-Aparicio, Maria del Prado; Kilian, Stephanus G; Steyn, Laurinda; Görgens, Johann

    2014-12-01

    The feasibility of ethanol production using an enzymatic hydrolysate of pretreated cladodes of Opuntia ficus-indica (prickly pear cactus) as carbohydrate feedstock was investigated, including a comprehensive chemical analysis of the cladode biomass and the effects of limited aeration on the fermentation profiles and sugar utilization. The low xylose and negligible mannose content of the cladode biomass used in this study suggested that the hemicellulose structure of the O. ficus-indica cladode was atypical of hardwood or softwood hemicelluloses. Separate hydrolysis and fermentation and simultaneous saccharification and fermentation procedures using Kluyveromyces marxianus and Saccharomyces cerevisiae at 40 and 35 °C, respectively, gave similar ethanol yields under non-aerated conditions. In oxygen-limited cultures K. marxianus exhibited almost double the ethanol productivity compared to non-aerated cultures, although after sugar depletion utilization of the produced ethanol was evident. Ethanol concentrations of up to 19.5 and 20.6 g l(-1) were obtained with K. marxianus and S. cerevisiae, respectively, representing 66 and 70 % of the theoretical yield on total sugars in the hydrolysate. Because of the low xylan content of the cladode biomass, a yeast capable of xylose fermentation might not be a prerequisite for ethanol production. K. marxianus, therefore, has potential as an alternative to S. cerevisiae for bioethanol production. However, the relatively low concentration of fermentable sugars in the O. ficus-indica cladode hydrolysate presents a technical constraint for commercial exploitation.

  11. ATG18 and FAB1 are involved in dehydration stress tolerance in Saccharomyces cerevisiae.

    PubMed

    López-Martínez, Gema; Margalef-Català, Mar; Salinas, Francisco; Liti, Gianni; Cordero-Otero, Ricardo

    2015-01-01

    Recently, different dehydration-based technologies have been evaluated for the purpose of cell and tissue preservation. Although some early results have been promising, they have not satisfied the requirements for large-scale applications. The long experience of using quantitative trait loci (QTLs) with the yeast Saccharomyces cerevisiae has proven to be a good model organism for studying the link between complex phenotypes and DNA variations. Here, we use QTL analysis as a tool for identifying the specific yeast traits involved in dehydration stress tolerance. Three hybrids obtained from stable haploids and sequenced in the Saccharomyces Genome Resequencing Project showed intermediate dehydration tolerance in most cases. The dehydration resistance trait of 96 segregants from each hybrid was quantified. A smooth, continuous distribution of the anhydrobiosis tolerance trait was found, suggesting that this trait is determined by multiple QTLs. Therefore, we carried out a QTL analysis to identify the determinants of this dehydration tolerance trait at the genomic level. Among the genes identified after reciprocal hemizygosity assays, RSM22, ATG18 and DBR1 had not been referenced in previous studies. We report new phenotypes for these genes using a previously validated test. Finally, our data illustrates the power of this approach in the investigation of the complex cell dehydration phenotype.

  12. ATG18 and FAB1 Are Involved in Dehydration Stress Tolerance in Saccharomyces cerevisiae

    PubMed Central

    López-Martínez, Gema; Margalef-Català, Mar; Salinas, Francisco; Liti, Gianni; Cordero-Otero, Ricardo

    2015-01-01

    Recently, different dehydration-based technologies have been evaluated for the purpose of cell and tissue preservation. Although some early results have been promising, they have not satisfied the requirements for large-scale applications. The long experience of using quantitative trait loci (QTLs) with the yeast Saccharomyces cerevisiae has proven to be a good model organism for studying the link between complex phenotypes and DNA variations. Here, we use QTL analysis as a tool for identifying the specific yeast traits involved in dehydration stress tolerance. Three hybrids obtained from stable haploids and sequenced in the Saccharomyces Genome Resequencing Project showed intermediate dehydration tolerance in most cases. The dehydration resistance trait of 96 segregants from each hybrid was quantified. A smooth, continuous distribution of the anhydrobiosis tolerance trait was found, suggesting that this trait is determined by multiple QTLs. Therefore, we carried out a QTL analysis to identify the determinants of this dehydration tolerance trait at the genomic level. Among the genes identified after reciprocal hemizygosity assays, RSM22, ATG18 and DBR1 had not been referenced in previous studies. We report new phenotypes for these genes using a previously validated test. Finally, our data illustrates the power of this approach in the investigation of the complex cell dehydration phenotype. PMID:25803831

  13. The architecture of the DNA replication origin recognition complex in Saccharomyces cerevisiae

    PubMed Central

    Chen, Zhiqiang; Speck, Christian; Wendel, Patricia; Tang, Chunyan; Stillman, Bruce; Li, Huilin

    2008-01-01

    The origin recognition complex (ORC) is conserved in all eukaryotes. The six proteins of the Saccharomyces cerevisiae ORC that form a stable complex bind to origins of DNA replication and recruit prereplicative complex (pre-RC) proteins, one of which is Cdc6. To further understand the function of ORC we recently determined by single-particle reconstruction of electron micrographs a low-resolution, 3D structure of S. cerevisiae ORC and the ORC–Cdc6 complex. In this article, the spatial arrangement of the ORC subunits within the ORC structure is described. In one approach, a maltose binding protein (MBP) was systematically fused to the N or the C termini of the five largest ORC subunits, one subunit at a time, generating 10 MBP-fused ORCs, and the MBP density was localized in the averaged, 2D EM images of the MBP-fused ORC particles. Determining the Orc1–5 structure and comparing it with the native ORC structure localized the Orc6 subunit near Orc2 and Orc3. Finally, subunit–subunit interactions were determined by immunoprecipitation of ORC subunits synthesized in vitro. Based on the derived ORC architecture and existing structures of archaeal Orc1–DNA structures, we propose a model for ORC and suggest how ORC interacts with origin DNA and Cdc6. The studies provide a basis for understanding the overall structure of the pre-RC. PMID:18647841

  14. Improving the Performance of the Granulosis Virus of Codling Moth (Lepidoptera: Tortricidae) by Adding the Yeast Saccharomyces cerevisiae with Sugar.

    PubMed

    Knight, Alan L; Basoalto, Esteban; Witzgall, Peter

    2015-04-01

    Studies were conducted with the codling moth granulosis virus (CpGV) to evaluate whether adding the yeast Saccharomyces cerevisiae Meyen ex E. C. Hansen with brown cane sugar could improve larval control of Cydia pomonella (L.). Larval mortalities in dipped-apple bioassays with S. cerevisiae or sugar alone were not significantly different from the water control. The addition of S. cerevisiae but not sugar with CpGV significantly increased larval mortality compared with CpGV alone. The combination of S. cerevisiae and sugar with CpGV significantly increased larval mortality compared with CpGV plus either additive alone. The addition of S. cerevisiae improved the efficacy of CpGV similarly to the use of the yeast Metschnikowia pulcherrima (isolated from field-collected larvae). The proportion of uninjured fruit in field trials was significantly increased with the addition of S. cerevisiae and sugar to CpGV compared with CpGV alone only in year 1, and from the controls in both years. In comparison, larval mortality was significantly increased in both years with the addition of S. cerevisiae and sugar with CpGV compared with CpGV alone or from the controls. The numbers of overwintering larvae on trees was significantly reduced from the control following a seasonal program of CpGV plus S. cerevisiae and sugar. The addition of a microencapsulated formulation of pear ester did not improve the performance of CpGV or CpGV plus S. cerevisiae and sugar. These data suggest that yeasts can enhance the effectiveness of the biological control agent CpGV, in managing and maintaining codling moth at low densities. Published by Oxford University Press on behalf of Entomological Society of America 2015. This work is written by US Government employees and is in the public domain in the US.

  15. Distribution patterns of Saccharomyces species in cultural landscapes of Germany.

    PubMed

    Brysch-Herzberg, Michael; Seidel, Martin

    2017-08-01

    The distribution patterns of the three Saccharomyces species, Saccharomyces paradoxus, S. uvarum and S. cerevisiae, were investigated by a culture-dependent approach in order to understand better how these species propagate in the cultural landscape of Germany. Saccharomyces paradoxus, the closest relative of S. cerevisiae, is shown to be a true woodland species. It was frequently found in the soil under conifers indicating that S. paradoxus is an autochthonous member of the microbial community in this habitat. Physiological characteristics of the species like the Crabtree effect and high tolerance against ethanol suggest that the species is adapted to regular supply with considerable amounts of sugars. Additionally, a high proportion of the S. paradoxus strains isolated in this study are shown to have the rare ability to ferment melezitose. For these reasons, it is hypothesized that S. paradoxus may be closely associated with the honeydew system in forests. Saccharomyces cerevisiae was rare in most habitats and only exceeded the frequency of S. paradoxus in habitats characterized by modern agricultural mass production of fruit. Both the landscape structure and the agricultural system heavily influence the frequencies of Saccharomyces species. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  16. Behavior of Lactobacillus plantarum and Saccharomyces cerevisiae in fresh and thermally processed orange juice.

    PubMed

    Alwazeer, Duried; Cachon, Remy; Divies, Charles

    2002-10-01

    Lactobacillus plantarum and Saccharomyces cerevisiae are acid-tolerant microorganisms that are able to spoil citrus juices before and after pasteurization. The growth of these microorganisms in orange juice with and without pasteurization was investigated. Two samples of orange juice were inoculated with ca. 10(5) CFU/ml of each microorganism. Others were inoculated with ca. 10(7) CFU/ml of each microorganism and then thermally treated. L. plantarum populations were reduced by 2.5 and <1 log10 CFU/ml at 60 degrees C for 40 s and at 55 degrees C for 40 s, respectively. For the same treatments, S. cerevisiae populations were reduced by >6 and 2 log10 CFU/ml, respectively. Samples of heated and nonheated juice were incubated at 15 degrees C for 20 days. Injured populations of L. plantarum decreased by ca. 2 log10 CFU/ml during the first 70 h of storage, but those of S. cerevisiae did not decrease. The length of the lag phase after pasteurization increased 6.2-fold for L. plantarum and 1.9-fold for S. cerevisiae, and generation times increased by 41 and 86%, respectively. The results of this study demonstrate the differences in the capabilities of intact and injured cells of spoilage microorganisms to spoil citrus juice and the different thermal resistance levels of cells. While L. plantarum was more resistant to heat treatment than S. cerevisiae was, growth recovery after pasteurization was faster for the latter microorganism.

  17. Oxygen requirements for formation and activity of the squalene expoxidase in Saccharomyces cerevisiae

    NASA Technical Reports Server (NTRS)

    Jahnke, L.; Klein, H. P.

    1983-01-01

    The effect of oxygen on squalene epoxidase activity in Saccharomyces cerevisiae was investigated. In cells grown in standing cultures, the epoxidase was localized mainly in the 'mitochondrial' fraction. Upon aeration, enzyme activity increased and the newly formed enzyme was associated with the 'microsomal' fraction. At 0.03 percent (vol/vol) oxygen, epoxidase levels doubled, whereas the ergosterol level was only slightly increased. Cycloheximide inhibited the increase in epoxidase under these conditions. An apparent K sub m for oxygen of 0.38 percent (vol/vol) was determined from a crude particulate preparation for the epoxidase.

  18. Saccharomyces cerevisiae Boulardii Reduces the Deoxynivalenol-Induced Alteration of the Intestinal Transcriptome.

    PubMed

    Alassane-Kpembi, Imourana; Pinton, Philippe; Hupé, Jean-François; Neves, Manon; Lippi, Yannick; Combes, Sylvie; Castex, Mathieu; Oswald, Isabelle P

    2018-05-15

    Type B trichothecene mycotoxin deoxynivalenol (DON) is one of the most frequently occurring food contaminants. By inducing trans-activation of a number of pro-inflammatory cytokines and increasing the stability of their mRNA, trichothecene can impair intestinal health. Several yeast products, especially Saccharomyces cerevisiae , have the potential for improving the enteric health of piglets, but little is known about the mechanisms by which the administration of yeast counteracts the DON-induced intestinal alterations. Using a pig jejunum explant model, a whole-transcriptome analysis was performed to decipher the early response of the small intestine to the deleterious effects of DON after administration of S. cerevisiae boulardii strain CNCM I-1079. Compared to the control condition, no differentially expressed gene (DE) was observed after treatment by yeast only. By contrast, 3619 probes-corresponding to 2771 genes-were differentially expressed following exposure to DON, and 32 signaling pathways were identified from the IPA software functional analysis of the set of DE genes. When the intestinal explants were treated with S. cerevisiae boulardii prior to DON exposure, the number of DE genes decreased by half (1718 probes corresponding to 1384 genes). Prototypical inflammation signaling pathways triggered by DON, including NF-κB and p38 MAPK, were reversed, although the yeast demonstrated limited efficacy toward some other pathways. S. cerevisiae boulardii also restored the lipid metabolism signaling pathway, and reversed the down-regulation of the antioxidant action of vitamin C signaling pathway. The latter effect could reduce the burden of DON-induced oxidative stress. Altogether, the results show that S. cerevisiae boulardii reduces the DON-induced alteration of intestinal transcriptome, and point to new mechanisms for the healing of tissue injury by yeast.

  19. Saccharomyces cerevisiae boulardii Reduces the Deoxynivalenol-Induced Alteration of the Intestinal Transcriptome

    PubMed Central

    Alassane-Kpembi, Imourana; Hupé, Jean-François; Neves, Manon; Lippi, Yannick; Combes, Sylvie; Castex, Mathieu

    2018-01-01

    Type B trichothecene mycotoxin deoxynivalenol (DON) is one of the most frequently occurring food contaminants. By inducing trans-activation of a number of pro-inflammatory cytokines and increasing the stability of their mRNA, trichothecene can impair intestinal health. Several yeast products, especially Saccharomyces cerevisiae, have the potential for improving the enteric health of piglets, but little is known about the mechanisms by which the administration of yeast counteracts the DON-induced intestinal alterations. Using a pig jejunum explant model, a whole-transcriptome analysis was performed to decipher the early response of the small intestine to the deleterious effects of DON after administration of S. cerevisiae boulardii strain CNCM I-1079. Compared to the control condition, no differentially expressed gene (DE) was observed after treatment by yeast only. By contrast, 3619 probes—corresponding to 2771 genes—were differentially expressed following exposure to DON, and 32 signaling pathways were identified from the IPA software functional analysis of the set of DE genes. When the intestinal explants were treated with S. cerevisiae boulardii prior to DON exposure, the number of DE genes decreased by half (1718 probes corresponding to 1384 genes). Prototypical inflammation signaling pathways triggered by DON, including NF-κB and p38 MAPK, were reversed, although the yeast demonstrated limited efficacy toward some other pathways. S. cerevisiae boulardii also restored the lipid metabolism signaling pathway, and reversed the down-regulation of the antioxidant action of vitamin C signaling pathway. The latter effect could reduce the burden of DON-induced oxidative stress. Altogether, the results show that S. cerevisiae boulardii reduces the DON-induced alteration of intestinal transcriptome, and point to new mechanisms for the healing of tissue injury by yeast. PMID:29762474

  20. Genomic diversity of Saccharomyces cerevisiae yeasts associated with alcoholic fermentation of bacanora produced by artisanal methods.

    PubMed

    Álvarez-Ainza, M L; Zamora-Quiñonez, K A; Moreno-Ibarra, G M; Acedo-Félix, E

    2015-03-01

    Bacanora is a spirituous beverage elaborated with Agave angustifolia Haw in an artisanal process. Natural fermentation is mostly performed with native yeasts and bacteria. In this study, 228 strains of yeast like Saccharomyces were isolated from the natural alcoholic fermentation on the production of bacanora. Restriction analysis of the amplified region ITS1-5.8S-ITS2 of the ribosomal DNA genes (RFLPr) were used to confirm the genus, and 182 strains were identified as Saccharomyces cerevisiae. These strains displayed high genomic variability in their chromosomes profiles by karyotyping. Electrophoretic profiles of the strains evaluated showed a large number of chromosomes the size of which ranged between 225 and 2200 kpb approximately.

  1. Starmerella bombicola influences the metabolism of Saccharomyces cerevisiae at pyruvate decarboxylase and alcohol dehydrogenase level during mixed wine fermentation

    PubMed Central

    2012-01-01

    Background The use of a multistarter fermentation process with Saccharomyces cerevisiae and non-Saccharomyces wine yeasts has been proposed to simulate natural must fermentation and to confer greater complexity and specificity to wine. In this context, the combined use of S. cerevisiae and immobilized Starmerella bombicola cells (formerly Candida stellata) was assayed to enhance glycerol concentration, reduce ethanol content and to improve the analytical composition of wine. In order to investigate yeast metabolic interaction during controlled mixed fermentation and to evaluate the influence of S. bombicola on S. cerevisiae, the gene expression and enzymatic activity of two key enzymes of the alcoholic fermentation pathway such as pyruvate decarboxylase (Pdc1) and alcohol dehydrogenase (Adh1) were studied. Results The presence of S. bombicola immobilized cells in a mixed fermentation trial confirmed an increase in fermentation rate, a combined consumption of glucose and fructose, an increase in glycerol and a reduction in the production of ethanol as well as a modification in the fermentation of by products. The alcoholic fermentation of S. cerevisiae was also influenced by S. bombicola immobilized cells. Indeed, Pdc1 activity in mixed fermentation was lower than that exhibited in pure culture while Adh1 activity showed an opposite behavior. The expression of both PDC1 and ADH1 genes was highly induced at the initial phase of fermentation. The expression level of PDC1 at the end of fermentation was much higher in pure culture while ADH1 level was similar in both pure and mixed fermentations. Conclusion In mixed fermentation, S. bombicola immobilized cells greatly affected the fermentation behavior of S. cerevisiae and the analytical composition of wine. The influence of S. bombicola on S. cerevisiae was not limited to a simple additive contribution. Indeed, its presence caused metabolic modifications during S. cerevisiae fermentation causing variation in the gene

  2. Impact of Commercial Strain Use on Saccharomyces cerevisiae Population Structure and Dynamics in Pinot Noir Vineyards and Spontaneous Fermentations of a Canadian Winery

    PubMed Central

    Martiniuk, Jonathan T.; Pacheco, Braydon; Russell, Gordon; Tong, Stephanie; Backstrom, Ian; Measday, Vivien

    2016-01-01

    Wine is produced by one of two methods: inoculated fermentation, where a commercially-produced, single Saccharomyces cerevisiae (S. cerevisiae) yeast strain is used; or the traditional spontaneous fermentation, where yeast present on grape and winery surfaces carry out the fermentative process. Spontaneous fermentations are characterized by a diverse succession of yeast, ending with one or multiple strains of S. cerevisiae dominating the fermentation. In wineries using both fermentation methods, commercial strains may dominate spontaneous fermentations. We elucidate the impact of the winery environment and commercial strain use on S. cerevisiae population structure in spontaneous fermentations over two vintages by comparing S. cerevisiae populations in aseptically fermented grapes from a Canadian Pinot Noir vineyard to S. cerevisiae populations in winery-conducted fermentations of grapes from the same vineyard. We also characterize the vineyard-associated S. cerevisiae populations in two other geographically separate Pinot Noir vineyards farmed by the same winery. Winery fermentations were not dominated by commercial strains, but by a diverse number of strains with genotypes similar to commercial strains, suggesting that a population of S. cerevisiae derived from commercial strains is resident in the winery. Commercial and commercial-related yeast were also identified in the three vineyards examined, although at a lower frequency. There is low genetic differentiation and S. cerevisiae population structure between vineyards and between the vineyard and winery that persisted over both vintages, indicating commercial yeast are a driver of S. cerevisiae population structure. We also have evidence of distinct and persistent populations of winery and vineyard-associated S. cerevisiae populations unrelated to commercial strains. This study is the first to characterize S. cerevisiae populations in Canadian vineyards. PMID:27551920

  3. Impact of Commercial Strain Use on Saccharomyces cerevisiae Population Structure and Dynamics in Pinot Noir Vineyards and Spontaneous Fermentations of a Canadian Winery.

    PubMed

    Martiniuk, Jonathan T; Pacheco, Braydon; Russell, Gordon; Tong, Stephanie; Backstrom, Ian; Measday, Vivien

    2016-01-01

    Wine is produced by one of two methods: inoculated fermentation, where a commercially-produced, single Saccharomyces cerevisiae (S. cerevisiae) yeast strain is used; or the traditional spontaneous fermentation, where yeast present on grape and winery surfaces carry out the fermentative process. Spontaneous fermentations are characterized by a diverse succession of yeast, ending with one or multiple strains of S. cerevisiae dominating the fermentation. In wineries using both fermentation methods, commercial strains may dominate spontaneous fermentations. We elucidate the impact of the winery environment and commercial strain use on S. cerevisiae population structure in spontaneous fermentations over two vintages by comparing S. cerevisiae populations in aseptically fermented grapes from a Canadian Pinot Noir vineyard to S. cerevisiae populations in winery-conducted fermentations of grapes from the same vineyard. We also characterize the vineyard-associated S. cerevisiae populations in two other geographically separate Pinot Noir vineyards farmed by the same winery. Winery fermentations were not dominated by commercial strains, but by a diverse number of strains with genotypes similar to commercial strains, suggesting that a population of S. cerevisiae derived from commercial strains is resident in the winery. Commercial and commercial-related yeast were also identified in the three vineyards examined, although at a lower frequency. There is low genetic differentiation and S. cerevisiae population structure between vineyards and between the vineyard and winery that persisted over both vintages, indicating commercial yeast are a driver of S. cerevisiae population structure. We also have evidence of distinct and persistent populations of winery and vineyard-associated S. cerevisiae populations unrelated to commercial strains. This study is the first to characterize S. cerevisiae populations in Canadian vineyards.

  4. Calorie restriction extends the chronological lifespan of Saccharomyces cerevisiae independently of the Sirtuins.

    PubMed

    Smith, Daniel L; McClure, Julie M; Matecic, Mirela; Smith, Jeffrey S

    2007-10-01

    Calorie restriction (CR) extends the mean and maximum lifespan of a wide variety of organisms ranging from yeast to mammals, although the molecular mechanisms of action remain unclear. For the budding yeast Saccharomyces cerevisiae reducing glucose in the growth medium extends both the replicative and chronological lifespans (CLS). The conserved NAD(+)-dependent histone deacetylase, Sir2p, promotes replicative longevity in S. cerevisiae by suppressing recombination within the ribosomal DNA locus and has been proposed to mediate the effects of CR on aging. In this study, we investigated the functional relationships of the yeast Sirtuins (Sir2p, Hst1p, Hst2p, Hst3p and Hst4p) with CLS and CR. SIR2, HST2, and HST4 were not major regulators of CLS and were not required for the lifespan extension caused by shifting the glucose concentration from 2 to 0.5% (CR). Deleting HST1 or HST3 moderately shortened CLS, but did not prevent CR from extending lifespan. CR therefore works through a Sirtuin-independent mechanism in the chronological aging system. We also show that low temperature or high osmolarity additively extends CLS when combined with CR, suggesting that these stresses and CR act through separate pathways. The CR effect on CLS was not specific to glucose. Restricting other simple sugars such as galactose or fructose also extended lifespan. Importantly, growth on nonfermentable carbon sources that force yeast to exclusively utilize respiration extended lifespan at nonrestricted concentrations and provided no additional benefit when restricted, suggesting that elevated respiration capacity is an important determinant of chronological longevity.

  5. Functional expression of Schizosaccharomyces pombe Vba2p in the vacuolar membrane of Saccharomyces cerevisiae.

    PubMed

    Pongcharoen, Pongsanat; Kawano-Kawada, Miyuki; Iwaki, Tomoko; Sugimoto, Naoko; Sekito, Takayuki; Akiyama, Koichi; Takegawa, Kaoru; Kakinuma, Yoshimi

    2013-01-01

    A vacuolar membrane protein, Vba2p of Schizosaccharomyces pombe, is involved in basic amino acid uptake by intact cells. Here we found evidence that Vba2p mediated ATP-dependent lysine uptake by vacuolar membrane vesicles of Saccharomyces cerevisiae. Vba2p was also responsible for quinidine sensitivity, and the addition of lysine improved cell growth on quinidine-containing media. These findings should be useful for further characterization of Vba2p.

  6. Crystallization and preliminary X-ray analysis of CTP:phosphoethanolamine cytidylyltransferase (ECT) from Saccharomyces cerevisiae

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

    Ohtsuka, Jun; Nagata, Koji; Lee, Woo Cheol

    2006-10-01

    CTP:phosphoethanolamine cytidylyltransferase from S. cerevisiae has been expressed, purified and crystallized. CTP:phosphoethanolamine cytidylyltransferase (ECT) is the enzyme that catalyzes the conversion of phosphoethanolamine to CDP-ethanolamine in the phosphatidylethanolamine-biosynthetic pathway (Kennedy pathway). ECT from Saccharomyces cerevisiae was crystallized by the sitting-drop vapour-diffusion method using PEG 4000 as precipitant. The crystals diffracted X-rays from a synchrotron-radiation source to 1.88 Å resolution. The space group was assigned as primitive tetragonal, P4{sub 1}2{sub 1}2 or P4{sub 3}2{sub 1}2, with unit-cell parameters a = b = 66.3, c = 150.8 Å. The crystals contain one ECT molecule in the asymmetric unit (V{sub M} = 2.2more » Å{sup 3} Da{sup −1}), with a solvent content of 43%.« less

  7. Secretory production of cell wall components by Saccharomyces cerevisiae protoplasts in static liquid culture.

    PubMed

    Aoyagi, Hideki; Ishizaka, Mikiko; Tanaka, Hideo

    2012-04-01

    When protoplasts of Saccharomyces cerevisiae T7 and IFO 0309 are cultured in a static liquid culture at 2.5 × 10(6) protoplasts/ml, cell wall regeneration does not occur and cell wall components (CWC) are released into the culture broth. By using a specialized fluorometer, the concentrations of CWC could be measured on the basis of the fluorescence intensity of the CWC after staining with Fluostain I. The inoculum concentration, pH, and osmotic pressure of the medium were important factors for the production of CWC in culture. Under optimal culture conditions, S. cerevisiae T7 protoplasts produced 0.91 mg/ml CWC after 24 h. The CWC induced the tumor necrosis factor-α production about 1.3 times higher than that of the commercially available β-1,3/1,6-glucan from baker's yeast cells.

  8. Ethanol production using immobilized Saccharomyces cerevisiae in lyophilized cellulose gel.

    PubMed

    Winkelhausen, Eleonora; Velickova, Elena; Amartey, Samuel A; Kuzmanova, Slobodanka

    2010-12-01

    A new lyophilization technique was used for immobilization of Saccharomyces cerevisiae cells in hydroxyethylcellulose (HEC) gels. The suitability of the lyophilized HEC gels to serve as immobilization matrices for the yeast cells was assessed by calculating the immobilization efficiency and the cell retention in three consecutive batches, each in duration of 72 h. Throughout the repeated batch fermentation, the immobilization efficiency was almost constant with an average value of 0.92 (12-216 h). The maximum value of cell retention was 0.24 g immobilized cells/g gel. Both parameters indicated that lyophilized gels are stable and capable of retaining the immobilized yeast cells. Showing the yeast cells propagation within the polymeric matrix, the scanning electron microscope images also confirmed that the lyophilization technique for immobilization of S. cerevisiae cells in the HEC gels was successful. The activity of the immobilized yeast cells was demonstrated by their capacity to convert glucose to ethanol. Ethanol yield of 0.40, 0.43 and 0.30 g ethanol/g glucose corresponding to 79%, 84% and 60% of the theoretical yield was attained in the first, second and third batches, respectively. The cell leakage was less than 10% of the average concentration of the immobilized cells.

  9. Improvement of Lead Tolerance of Saccharomyces cerevisiae by Random Mutagenesis of Transcription Regulator SPT3.

    PubMed

    Zhu, Liying; Gao, Shan; Zhang, Hongman; Huang, He; Jiang, Ling

    2018-01-01

    Bioremediation of heavy metal pollution with biomaterials such as bacteria and fungi usually suffer from limitations because of microbial sensitivity to high concentration of heavy metals. Herein, we adopted a novel random mutagenesis technique called RAISE to manipulate the transcription regulator SPT3 of Saccharomyces cerevisiae to improve cell lead tolerance. The best strain Mutant VI was selected from the random mutagenesis libraries on account of the growth performance, with higher specific growth rate than the control strain (0.068 vs. 0.040 h -1 ) at lead concentration as high as 1.8 g/L. Combined with the transcriptome analysis of S. cerevisiae, expressing the SPT3 protein was performed to make better sense of the global regulatory effects of SPT3. The data analysis revealed that 57 of S. cerevisiae genes were induced and 113 genes were suppressed, ranging from those for trehalose synthesis, carbon metabolism, and nucleotide synthesis to lead resistance. Especially, the accumulation of intracellular trehalose in S. cerevisiae under certain conditions of stress is considered important to lead resistance. The above results represented that SPT3 was acted as global transcription regulator in the exponential phase of strain and accordingly improved heavy metal tolerance in the heterologous host S. cerevisiae. The present study provides a route to complex phenotypes that are not readily accessible by traditional methods.

  10. Signature gene expressions of cell wall integrity pathway concur with tolerance response of industrial yeast Saccharomyces cerevisiae against biomass pretreatment inhibitors

    USDA-ARS?s Scientific Manuscript database

    Traditional industrial ethanologenic yeast Saccharomyces cerevisiae has a robust performance under various environmental conditions and can be served as a candidate for the next-generation biocatalyst development for advanced biofuels production using lignocellulose mateials. Overcoming toxic compou...

  11. Xylose Isomerase Improves Growth and Ethanol Production Rates from Biomass Sugars for Both Saccharomyces Pastorianus and Saccharomyces Cerevisiae

    PubMed Central

    Miller, Kristen P.; Gowtham, Yogender Kumar; Henson, J. Michael; Harcum, Sarah W.

    2013-01-01

    The demand for biofuel ethanol made from clean, renewable nonfood sources is growing. Cellulosic biomass, such as switch grass (Panicum virgatum L.), is an alternative feedstock for ethanol production; however, cellulosic feedstock hydrolysates contain high levels of xylose, which needs to be converted to ethanol to meet economic feasibility. In this study, the effects of xylose isomerase on cell growth and ethanol production from biomass sugars representative of switch grass were investigated using low cell density cultures. The lager yeast species Saccharomyces pastorianus was grown with immobilized xylose isomerase in the fermentation step to determine the impact of the glucose and xylose concentrations on the ethanol production rates. Ethanol production rates were improved due to xylose isomerase; however, the positive effect was not due solely to the conversion of xylose to xylulose. Xylose isomerase also has glucose isomerase activity, so to better understand the impact of the xylose isomerase on S. pastorianus, growth and ethanol production were examined in cultures provided fructose as the sole carbon. It was observed that growth and ethanol production rates were higher for the fructose cultures with xylose isomerase even in the absence of xylose. To determine whether the positive effects of xylose isomerase extended to other yeast species, a side-by-side comparison of S. pastorianus and Saccharomyces cerevisiae was conducted. These comparisons demonstrated that the xylose isomerase increased ethanol productivity for both the yeast species by increasing the glucose consumption rate. These results suggest that xylose isomerase can contribute to improved ethanol productivity, even without significant xylose conversion. PMID:22866331

  12. Genetic Causes of Phenotypic Adaptation to the Second Fermentation of Sparkling Wines in Saccharomyces cerevisiae

    PubMed Central

    Martí-Raga, Maria; Peltier, Emilien; Mas, Albert; Beltran, Gemma; Marullo, Philippe

    2016-01-01

    Hybridization is known to improve complex traits due to heterosis and phenotypic robustness. However, these phenomena have been rarely explained at the molecular level. Here, the genetic determinism of Saccharomyces cerevisiae fermentation performance was investigated using a QTL mapping approach on an F1-progeny population. Three main QTL were detected, with positive alleles coming from both parental strains. The heterosis effect found in the hybrid was partially explained by three loci showing pseudooverdominance and dominance effects. The molecular dissection of those QTL revealed that the adaptation to second fermentation is related to pH, lipid, or osmotic regulation. Our results suggest that the stressful conditions of second fermentation have driven the selection of rare genetic variants adapted to maintain yeast cell homeostasis and, in particular, to low pH conditions. PMID:27903630

  13. Improved Acetic Acid Resistance in Saccharomyces cerevisiae by Overexpression of the WHI2 Gene Identified through Inverse Metabolic Engineering.

    PubMed

    Chen, Yingying; Stabryla, Lisa; Wei, Na

    2016-01-29

    Development of acetic acid-resistant Saccharomyces cerevisiae is important for economically viable production of biofuels from lignocellulosic biomass, but the goal remains a critical challenge due to limited information on effective genetic perturbation targets for improving acetic acid resistance in the yeast. This study employed a genomic-library-based inverse metabolic engineering approach to successfully identify a novel gene target, WHI2 (encoding a cytoplasmatic globular scaffold protein), which elicited improved acetic acid resistance in S. cerevisiae. Overexpression of WHI2 significantly improved glucose and/or xylose fermentation under acetic acid stress in engineered yeast. The WHI2-overexpressing strain had 5-times-higher specific ethanol productivity than the control in glucose fermentation with acetic acid. Analysis of the expression of WHI2 gene products (including protein and transcript) determined that acetic acid induced endogenous expression of Whi2 in S. cerevisiae. Meanwhile, the whi2Δ mutant strain had substantially higher susceptibility to acetic acid than the wild type, suggesting the important role of Whi2 in the acetic acid response in S. cerevisiae. Additionally, overexpression of WHI2 and of a cognate phosphatase gene, PSR1, had a synergistic effect in improving acetic acid resistance, suggesting that Whi2 might function in combination with Psr1 to elicit the acetic acid resistance mechanism. These results improve our understanding of the yeast response to acetic acid stress and provide a new strategy to breed acetic acid-resistant yeast strains for renewable biofuel production. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  14. β-Glucan from Saccharomyces cerevisiae Induces IFN-γ Production In Vivo in BALB/c Mice.

    PubMed

    Javmen, Artur; Nemeikaitė-Čėnienė, Aušra; Bratchikov, Maksim; Grigiškis, Saulius; Grigas, Fortūnatas; Jonauskienė, Irena; Zabulytė, Danguolė; Mauricas, Mykolas

    2015-01-01

    β-Glucan is one of the most abundant polymers in nature and has been established as an immunomodulator. This compound has notable physiological effects on mammalian immune systems, including anti-tumor and anti-infective activities and can activate the immune response. It is considered that the immune-stimulating activities of β-glucan can depend on physicochemical parameters, such as molecular size. Saccharomyces cerevisiae, also known as baker's yeast, is a frequently used source of β-glucan. The aim of the experiments was to investigate how different Saccharomyces cerevisiae β-glucan preparations with different molecular size affect interferon-gamma (IFN-γ) production in BALB/c mice. In vivo and in vitro BALB/c mouse models were used for the investigations. Different β-glucan preparations were orally administrated in the in vivo experiments. IFN-γ production in BALB/c mice was analyzed by enzyme-linked immunosorbent assay and measuring interferon-γ RNA concentration. The results showed that orally-administered β-glucan from S. cerevisiae enhanced IFN-γ production in BALB/c mice in the in vivo model, but not by mouse leukocytes in vitro. Moreover, water-soluble β-glucan enhanced IFN-γ production more effectively than did particulate β-glucan. IFN-γ plays an important role in immunity against viral and bacterial infections. Our experiments have shown that β-glucan preparations enhance IFN-γ production in BALB/c mice and can be potentially used for immune system stimulation in mammals. Current results may be used to develop soluble β-glucan nutritional supplements. Copyright © 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  15. Design and engineering of intracellular-metabolite-sensing/regulation gene circuits in Saccharomyces cerevisiae.

    PubMed

    Wang, Meng; Li, Sijin; Zhao, Huimin

    2016-01-01

    The development of high-throughput phenotyping tools is lagging far behind the rapid advances of genotype generation methods. To bridge this gap, we report a new strategy for design, construction, and fine-tuning of intracellular-metabolite-sensing/regulation gene circuits by repurposing bacterial transcription factors and eukaryotic promoters. As proof of concept, we systematically investigated the design and engineering of bacterial repressor-based xylose-sensing/regulation gene circuits in Saccharomyces cerevisiae. We demonstrated that numerous properties, such as induction ratio and dose-response curve, can be fine-tuned at three different nodes, including repressor expression level, operator position, and operator sequence. By applying these gene circuits, we developed a cell sorting based, rapid and robust high-throughput screening method for xylose transporter engineering and obtained a sugar transporter HXT14 mutant with 6.5-fold improvement in xylose transportation capacity. This strategy should be generally applicable and highly useful for evolutionary engineering of proteins, pathways, and genomes in S. cerevisiae. © 2015 Wiley Periodicals, Inc.

  16. Metabolic Engineering of Saccharomyces cerevisiae for High-Level Production of Salidroside from Glucose.

    PubMed

    Jiang, Jingjie; Yin, Hua; Wang, Shuai; Zhuang, Yibin; Liu, Shaowei; Liu, Tao; Ma, Yanhe

    2018-05-02

    Salidroside is an important plant-derived aromatic compound with diverse biological properties. Because of inadequate natural resources, the supply of salidroside is currently limited. In this work, we engineered the production of salidroside in yeast. First, the aromatic aldehyde synthase (AAS) from Petroselinum crispum was overexpressed in Saccharomyces cerevisiae when combined with endogenous Ehrlich pathway to produce tyrosol from tyrosine. Glucosyltransferases from different resources were tested for ideal production of salidroside in the yeast. Metabolic flux was enhanced toward tyrosine biosynthesis by overexpressing pathway genes and eliminating feedback inhibition. The pathway genes were integrated into yeast chromosome, leading to a recombinant strain that produced 239.5 mg/L salidroside and 965.4 mg/L tyrosol. The production of salidroside and tyrosol reached up to 732.5 and 1394.6 mg/L, respectively, by fed-batch fermentation. Our work provides an alternative way for industrial large-scale production of salidroside and tyrosol from S. cerevisiae.

  17. A vacuolar membrane protein Avt7p is involved in transport of amino acid and spore formation in Saccharomyces cerevisiae.

    PubMed

    Tone, Junichi; Yamanaka, Atsushi; Manabe, Kunio; Murao, Nami; Kawano-Kawada, Miyuki; Sekito, Takayuki; Kakinuma, Yoshimi

    2015-01-01

    Active transport systems for various amino acids operate in the vacuolar membrane of Saccharomyces cerevisiae. The gene families for vacuolar amino acid transporters were identified by reverse genetics experiments. In the AVT transporter family, Avt1p works for active uptake of amino acid into vacuole, and Avt3p, Avt4p, and Avt6p for active extrusion of amino acid from vacuole to cytosol. Here, we found green fluorescent protein-tagged Avt7p, an unidentified member of the AVT family, localized to the vacuolar membrane of S. cerevisiae. Disruption of the AVT7 gene enhanced both vacuolar contents of several amino acids and uptake activities of glutamine and proline by vacuolar membrane vesicles. Efficiency of spore formation was impaired by the disruption of the AVT7 gene, suggesting the physiological importance of Avt7p-dependent efflux of amino acid from vacuoles under nutrient-poor condition.

  18. Efficient removal of atrazine from aqueous solutions using magnetic Saccharomyces cerevisiae bionanomaterial.

    PubMed

    Wu, Xin; He, Huijun; Yang, William L; Yu, Jiaping; Yang, Chunping

    2018-06-17

    A novel bionanomaterial comprising Saccharomyces cerevisiae (S. cerevisiae) and Fe 3 O 4 nanoparticles encapsulated in a sodium alginate-polyvinyl alcohol (SA-PVA) matrix was synthesized for the efficient removal of atrazine from aqueous solutions. The effects of the operating parameters, nitrogen source, and glucose and Fe 3+ contents on atrazine removal were investigated, and the intermediates were detected by gas chromatography-mass spectrometry (GC-MS). In addition, the synthesized Fe 3 O 4 particles were characterized by XRD, EDX, HR-TEM, FTIR, and hysteresis loops, and the bionanomaterial was characterized by SEM. The results showed that the maximum removal efficiency of 100% was achieved at 28 °C, a pH of 7.0, and 150 rpm with an initial atrazine concentration of 2.0 mg L -1 and that the removal efficiency was still higher than 95.53% even when the initial atrazine concentration was 50 mg L -1 . Biodegradation was demonstrated to be the dominant removal mechanism for atrazine because atrazine was consumed as the sole carbon source for S. cerevisiae. The results of GC-MS showed that dechlorination, dealkylation, deamination, isomerization, and mineralization occurred in the process of atrazine degradation, and thus, a new degradation pathway was proposed. These results indicated that this bionanomaterial has great potential for the bioremediation of atrazine-contaminated water.

  19. Expression of an Aspergillus niger Phytase Gene (phyA) in Saccharomyces cerevisiae

    PubMed Central

    Han, Yanming; Wilson, David B.; Lei, Xin gen

    1999-01-01

    Phytase improves the bioavailability of phytate phosphorus in plant foods to humans and animals and reduces phosphorus pollution of animal waste. Our objectives were to express an Aspergillus niger phytase gene (phyA) in Saccharomyces cerevisiae and to determine the effects of glycosylation on the phytase’s activity and thermostability. A 1.4-kb DNA fragment containing the coding region of the phyA gene was inserted into the expression vector pYES2 and was expressed in S. cerevisiae as an active, extracellular phytase. The yield of total extracellular phytase activity was affected by the signal peptide and the medium composition. The expressed phytase had two pH optima (2 to 2.5 and 5 to 5.5) and a temperature optimum between 55 and 60°C, and it cross-reacted with a rabbit polyclonal antibody against the wild-type enzyme. Due to the heavy glycosylation, the expressed phytase had a molecular size of approximately 120 kDa and appeared to be more thermostable than the commercial enzyme. Deglycosylation of the phytase resulted in losses of 9% of its activity and 40% of its thermostability. The recombinant phytase was effective in hydrolyzing phytate phosphorus from corn or soybean meal in vitro. In conclusion, the phyA gene was expressed as an active, extracellular phytase in S. cerevisiae, and its thermostability was affected by glycosylation. PMID:10223979

  20. Screening of transporters to improve xylodextrin utilization in the yeast Saccharomyces cerevisiae.

    PubMed

    Zhang, Chenlu; Acosta-Sampson, Ligia; Yu, Vivian Yaci; Cate, Jamie H D

    2017-01-01

    The economic production of cellulosic biofuel requires efficient and full utilization of all abundant carbohydrates naturally released from plant biomass by enzyme cocktails. Recently, we reconstituted the Neurospora crassa xylodextrin transport and consumption system in Saccharomyces cerevisiae, enabling growth of yeast on xylodextrins aerobically. However, the consumption rate of xylodextrin requires improvement for industrial applications, including consumption in anaerobic conditions. As a first step in this improvement, we report analysis of orthologues of the N. crassa transporters CDT-1 and CDT-2. Transporter ST16 from Trichoderma virens enables faster aerobic growth of S. cerevisiae on xylodextrins compared to CDT-2. ST16 is a xylodextrin-specific transporter, and the xylobiose transport activity of ST16 is not inhibited by cellobiose. Other transporters identified in the screen also enable growth on xylodextrins including xylotriose. Taken together, these results indicate that multiple transporters might prove useful to improve xylodextrin utilization in S. cerevisiae. Efforts to use directed evolution to improve ST16 from a chromosomally-integrated copy were not successful, due to background growth of yeast on other carbon sources present in the selection medium. Future experiments will require increasing the baseline growth rate of the yeast population on xylodextrins, to ensure that the selective pressure exerted on xylodextrin transport can lead to isolation of improved xylodextrin transporters.

  1. The use of genetically modified Saccharomyces cerevisiae strains in the wine industry.

    PubMed

    Schuller, Dorit; Casal, Margarida

    2005-08-01

    In recent decades, science and food technology have contributed at an accelerated rate to the introduction of new products to satisfy nutritional, socio-economic and quality requirements. With the emergence of modern molecular genetics, the industrial importance of Saccharomyces cerevisiae, is continuously extended. The demand for suitable genetically modified (GM) S. cerevisiae strains for the biofuel, bakery and beverage industries or for the production of biotechnological products (e.g. enzymes, pharmaceutical products) will continuously grow in the future. Numerous specialised S. cerevisiae wine strains were obtained in recent years, possessing a wide range of optimised or novel oenological properties, capable of satisfying the demanding nature of modern winemaking practise. The unlocking of transcriptome, proteome and metabolome complexities will contribute decisively to the knowledge about the genetic make-up of commercial yeast strains and will influence wine strain improvement via genetic engineering. The most relevant advances regarding the importance and implications of the use of GM yeast strains in the wine industry are discussed in this mini-review. In this work, various aspects are considered including the strategies used for the construction of strains with respect to current legislation requirements, the environmental risk evaluations concerning the deliberate release of genetically modified yeast strains, the methods for detection of recombinant DNA and protein that are currently under evaluation, and the reasons behind the critical public perception towards the application of such strains.

  2. Potential utilization of sorghum field waste for fuel ethanol production employing Pachysolen tannophilus and Saccharomyces cerevisiae.

    PubMed

    Sathesh-Prabu, C; Murugesan, A G

    2011-02-01

    In this study, we demonstrate that the sorghum field waste, sorghum stover could be used to produce fuel grade ethanol. The alkaline treatment of 2% NaOH for 8h removed 64% of lignin from sorghum stover. Maximum of 68 and 56 g/L of ethanol yield were obtained by Saccharomyces cerevisiae (MTCC 173) and Pachysolen tannophilus (MTCC 1077) from sorghum stover under optimized condition, respectively. pH and temperature were optimized for the better growth of S. cerevisiae and P. tannophilus. A total of 51% and 48% more ethanol yield was obtained at initial sugar concentration of 200 g/L than 150 g/L by P. tannophilus and S. cerevisiae, respectively. Respiratory deficiency and ethanol tolerance of the organisms were studied. This investigation showed that sorghum field waste could be effectively used for the production of fuel ethanol to avoid conflicts between human food use and industrial use of crops. Copyright © 2010 Elsevier Ltd. All rights reserved.

  3. Expression of an endoglucanase from Tribolium castaneum (TcEG1) in Saccharomyces cerevisiae.

    PubMed

    Shirley, Derek; Oppert, Cris; Reynolds, Todd B; Miracle, Bethany; Oppert, Brenda; Klingeman, William E; Jurat-Fuentes, Juan Luis

    2014-10-01

    Insects are a largely unexploited resource in prospecting for novel cellulolytic enzymes to improve the production of ethanol fuel from lignocellulosic biomass. The cost of lignocellulosic ethanol production is expected to decrease by the combination of cellulose degradation (saccharification) and fermentation of the resulting glucose to ethanol in a single process, catalyzed by the yeast Saccharomyces cerevisiae transformed to express efficient cellulases. While S. cerevisiae is an established heterologous expression system, there are no available data on the functional expression of insect cellulolytic enzymes for this species. To address this knowledge gap, S. cerevisiae was transformed to express the full-length cDNA encoding an endoglucanase from the red flour beetle, Tribolium castaneum (TcEG1), and evaluated the activity of the transgenic product (rTcEG1). Expression of the TcEG1 cDNA in S. cerevisiae was under control of the strong glyceraldehyde-3 phosphate dehydrogenase promoter. Cultured transformed yeast secreted rTcEG1 protein as a functional β-1,4-endoglucanase, which allowed transformants to survive on selective media containing cellulose as the only available carbon source. Evaluation of substrate specificity for secreted rTcEG1 demonstrated endoglucanase activity, although some activity was also detected against complex cellulose substrates. Potentially relevant to uses in biofuel production rTcEG1 activity increased with pH conditions, with the highest activity detected at pH 12. Our results demonstrate the potential for functional production of an insect cellulase in S. cerevisiae and confirm the stability of rTcEG1 activity in strong alkaline environments. © 2013 Institute of Zoology, Chinese Academy of Sciences.

  4. Reconstruction and Evaluation of the Synthetic Bacterial MEP Pathway in Saccharomyces cerevisiae

    PubMed Central

    Partow, Siavash; Siewers, Verena; Daviet, Laurent; Schalk, Michel; Nielsen, Jens

    2012-01-01

    Isoprenoids, which are a large group of natural and chemical compounds with a variety of applications as e.g. fragrances, pharmaceuticals and potential biofuels, are produced via two different metabolic pathways, the mevalonate (MVA) pathway and the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway. Here, we attempted to replace the endogenous MVA pathway in Saccharomyces cerevisiae by a synthetic bacterial MEP pathway integrated into the genome to benefit from its superior properties in terms of energy consumption and productivity at defined growth conditions. It was shown that the growth of a MVA pathway deficient S. cerevisiae strain could not be restored by the heterologous MEP pathway even when accompanied by the co-expression of genes erpA, hISCA1 and CpIscA involved in the Fe-S trafficking routes leading to maturation of IspG and IspH and E. coli genes fldA and fpr encoding flavodoxin and flavodoxin reductase believed to be responsible for electron transfer to IspG and IspH. PMID:23285068

  5. Iterative optimization of xylose catabolism in Saccharomyces cerevisiae using combinatorial expression tuning.

    PubMed

    Latimer, Luke N; Dueber, John E

    2017-06-01

    A common challenge in metabolic engineering is rapidly identifying rate-controlling enzymes in heterologous pathways for subsequent production improvement. We demonstrate a workflow to address this challenge and apply it to improving xylose utilization in Saccharomyces cerevisiae. For eight reactions required for conversion of xylose to ethanol, we screened enzymes for functional expression in S. cerevisiae, followed by a combinatorial expression analysis to achieve pathway flux balancing and identification of limiting enzymatic activities. In the next round of strain engineering, we increased the copy number of these limiting enzymes and again tested the eight-enzyme combinatorial expression library in this new background. This workflow yielded a strain that has a ∼70% increase in biomass yield and ∼240% increase in xylose utilization. Finally, we chromosomally integrated the expression library. This library enriched for strains with multiple integrations of the pathway, which likely were the result of tandem integrations mediated by promoter homology. Biotechnol. Bioeng. 2017;114: 1301-1309. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  6. Oxidative stress survival in a clinical Saccharomyces cerevisiae isolate is influenced by a major quantitative trait nucleotide.

    PubMed

    Diezmann, Stephanie; Dietrich, Fred S

    2011-07-01

    One of the major challenges in characterizing eukaryotic genetic diversity is the mapping of phenotypes that are the cumulative effect of multiple alleles. We have investigated tolerance of oxidative stress in the yeast Saccharomyces cerevisiae, a trait showing phenotypic variation in the population. Initial crosses identified that this is a quantitative trait. Microorganisms experience oxidative stress in many environments, including during infection of higher eukaryotes. Natural variation in oxidative stress tolerance is an important aspect of response to oxidative stress exerted by the human immune system and an important trait in microbial pathogens. A clinical isolate of the usually benign yeast S. cerevisiae was found to survive oxidative stress significantly better than the laboratory strain. We investigated the genetic basis of increased peroxide survival by crossing those strains, phenotyping 1500 segregants, and genotyping of high-survival segregants by hybridization of bulk and single segregant DNA to microarrays. This effort has led to the identification of an allele of the transcription factor Rds2 as contributing to stress response. Rds2 has not previously been associated with the survival of oxidative stress. The identification of its role in the oxidative stress response here is an example of a specific trait that appears to be beneficial to Saccharomyces cerevisiae when growing as a pathogen. Understanding the role of this fungal-specific transcription factor in pathogenicity will be important in deciphering how fungi infect and colonize the human host and could eventually lead to a novel drug target.

  7. A Saccharomyces cerevisiae Wine Strain Inhibits Growth and Decreases Ochratoxin A Biosynthesis by Aspergillus carbonarius and Aspergillus ochraceus

    PubMed Central

    Cubaiu, Loredana; Abbas, Hamid; Dobson, Alan D. W.; Budroni, Marilena; Migheli, Quirico

    2012-01-01

    The aim of this study was to select wine yeast strains as biocontrol agents against fungal contaminants responsible for the accumulation of ochratoxin A (OTA) in grape and wine and to dissect the mechanism of OTA detoxification by a Saccharomyces cerevisiae strain (DISAABA1182), which had previously been reported to reduce OTA in a synthetic must. All of the yeast strains tested displayed an ability to inhibit the growth of Aspergillus carbonarius both in vivo and in vitro and addition of culture filtrates from the tested isolates led to complete inhibition of OTA production. S. cerevisiae DISAABA1182 was selected and further tested for its capacity to inhibit OTA production and pks (polyketide synthase) transcription in A. carbonarius and Aspergillus ochraceus in vitro. In order to dissect the mechanism of OTA detoxification, each of these two fungi was co-cultured with living yeast cells exposed to yeast crude or to autoclaved supernatant: S. cerevisiae DISAABA1182 was found to inhibit mycelial growth and OTA production in both Aspergilli when co-cultured in the OTA-inducing YES medium. Moreover, a decrease in pks transcription was observed in the presence of living cells of S. cerevisiae DISAABA1182 or its supernatant, while no effects were observed on transcription of either of the constitutively expressed calmodulin and β-tubulin genes. This suggests that transcriptional regulation of OTA biosynthetic genes takes place during the interaction between DISAABA1182 and OTA-producing Aspergilli. PMID:23223175

  8. Multiplexed CRISPR/Cas9 Genome Editing and Gene Regulation Using Csy4 in Saccharomyces cerevisiae.

    PubMed

    Ferreira, Raphael; Skrekas, Christos; Nielsen, Jens; David, Florian

    2018-01-19

    Clustered regularly interspaced short palindromic repeats (CRISPR) technology has greatly accelerated the field of strain engineering. However, insufficient efforts have been made toward developing robust multiplexing tools in Saccharomyces cerevisiae. Here, we exploit the RNA processing capacity of the bacterial endoribonuclease Csy4 from Pseudomonas aeruginosa, to generate multiple gRNAs from a single transcript for genome editing and gene interference applications in S. cerevisiae. In regards to genome editing, we performed a quadruple deletion of FAA1, FAA4, POX1 and TES1 reaching 96% efficiency out of 24 colonies tested. Then, we used this system to efficiently transcriptionally regulate the three genes, OLE1, HMG1 and ACS1. Thus, we demonstrate that multiplexed genome editing and gene regulation can be performed in a fast and effective manner using Csy4.

  9. Enhancement of protein production via the strong DIT1 terminator and two RNA-binding proteins in Saccharomyces cerevisiae

    PubMed Central

    Ito, Yoichiro; Kitagawa, Takao; Yamanishi, Mamoru; Katahira, Satoshi; Izawa, Shingo; Irie, Kenji; Furutani-Seiki, Makoto; Matsuyama, Takashi

    2016-01-01

    Post-transcriptional upregulation is an effective way to increase the expression of transgenes and thus maximize the yields of target chemicals from metabolically engineered organisms. Refractory elements in the 3′ untranslated region (UTR) that increase mRNA half-life might be available. In Saccharomyces cerevisiae, several terminator regions have shown activity in increasing the production of proteins by upstream coding genes; among these terminators the DIT1 terminator has the highest activity. Here, we found in Saccharomyces cerevisiae that two resident trans-acting RNA-binding proteins (Nab6p and Pap1p) enhance the activity of the DIT1 terminator through the cis element GUUCG/U within the 3′-UTR. These two RNA-binding proteins could upregulate a battery of cell-wall–related genes. Mutagenesis of the DIT1 terminator improved its activity by a maximum of 500% of that of the standard PGK1 terminator. Further understanding and improvement of this system will facilitate inexpensive and stable production of complicated organism-derived drugs worldwide. PMID:27845367

  10. Effect of Ethanol Stress on Fermentation Performance of Saccharomyces cerevisiae Cells Immobilized on Nypa fruticans Leaf Sheath Pieces

    PubMed Central

    Nguyen, Hoang Phong; Du Le, Hoang

    2015-01-01

    Summary The yeast cells of Saccharomyces cerevisiae immobilized on Nypa fruticans leaf sheath pieces were tested for ethanol tolerance (0, 23.7, 47.4, 71.0 and 94.7 g/L). Increase in the initial ethanol concentration from 23.7 to 94.7 g/L decreased the average growth rate and concentration of ethanol produced by the immobilized yeast by 5.2 and 4.1 times, respectively. However, in the medium with initial ethanol concentration of 94.7 g/L, the average growth rate, glucose uptake rate and ethanol formation rate of the immobilized yeast were 3.7, 2.5 and 3.5 times, respectively, higher than those of the free yeast. The ethanol stress inhibited ethanol formation by Saccharomyces cerevisiae cells and the yeast responded to the stress by changing the fatty acid composition of cellular membrane. The adsorption of yeast cells on Nypa fruticans leaf sheath pieces of the growth medium increased the saturated fatty acid (C16:0 and C18:0) mass fraction in the cellular membrane and that improved alcoholic fermentation performance of the immobilized yeast. PMID:27904338

  11. Isolation and Characterization of Mms-Sensitive Mutants of SACCHAROMYCES CEREVISIAE

    PubMed Central

    Prakash, Louise; Prakash, Satya

    1977-01-01

    We have isolated mutants sensitive to methyl methanesulfonate (MMS) in Saccharomyces cerevisiae. Alleles of rad1, rad4, rad6, rad52, rad55 and rad57 were found among these mms mutants. Twenty-nine of the mms mutants which complement the existing radiation-sensitive (rad and rev ) mutants belong to 22 new complementation groups. Mutants from five complementation groups are sensitive only to MMS. Mutants of 11 complementation groups are sensitive to UV or X rays in addition to MMS, mutants of six complementation groups are sensitive to all three agents. The cross-sensitivities of these mms mutants to UV and X rays are discussed in terms of their possible involvement in DNA repair. Sporulation is reduced or absent in homozygous diploids of mms mutants from nine complementation groups. PMID:195865

  12. The Influence of Microgravity on Invasive Growth in Saccharomyces cerevisiae

    NASA Astrophysics Data System (ADS)

    Van Mulders, Sebastiaan E.; Stassen, Catherine; Daenen, Luk; Devreese, Bart; Siewers, Verena; van Eijsden, Rudy G. E.; Nielsen, Jens; Delvaux, Freddy R.; Willaert, Ronnie

    2011-01-01

    This study investigates the effects of microgravity on colony growth and the morphological transition from single cells to short invasive filaments in the model eukaryotic organism Saccharomyces cerevisiae. Two-dimensional spreading of the yeast colonies grown on semi-solid agar medium was reduced under microgravity in the Σ1278b laboratory strain but not in the CMBSESA1 industrial strain. This was supported by the Σ1278b proteome map under microgravity conditions, which revealed upregulation of proteins linked to anaerobic conditions. The Σ1278b strain showed a reduced invasive growth in the center of the yeast colony. Bud scar distribution was slightly affected, with a switch toward more random budding. Together, microgravity conditions disturb spatially programmed budding patterns and generate strain-dependent growth differences in yeast colonies on semi-solid medium.

  13. Morphogenetic Pathway of Spore Wall Assembly in Saccharomyces cerevisiae

    PubMed Central

    Coluccio, Alison; Bogengruber, Edith; Conrad, Michael N.; Dresser, Michael E.; Briza, Peter; Neiman, Aaron M.

    2004-01-01

    The Saccharomyces cerevisiae spore is protected from environmental damage by a multilaminar extracellular matrix, the spore wall, which is assembled de novo during spore formation. A set of mutants defective in spore wall assembly were identified in a screen for mutations causing sensitivity of spores to ether vapor. The spore wall defects in 10 of these mutants have been characterized in a variety of cytological and biochemical assays. Many of the individual mutants are defective in the assembly of specific layers within the spore wall, leading to arrests at discrete stages of assembly. The localization of several of these gene products has been determined and distinguishes between proteins that likely are involved directly in spore wall assembly and probable regulatory proteins. The results demonstrate that spore wall construction involves a series of dependent steps and provide the outline of a morphogenetic pathway for assembly of a complex extracellular structure. PMID:15590821

  14. Heterologous expression of Trametes versicolor laccase in Saccharomyces cerevisiae.

    PubMed

    Iimura, Yosuke; Sonoki, Tomonori; Habe, Hiroshi

    2018-01-01

    Laccase is used in various industrial fields, and it has been the subject of numerous studies. Trametes versicolor laccase has one of the highest redox potentials among the various forms of this enzyme. In this study, we optimized the expression of laccase in Saccharomyces cerevisiae. Optimizing the culture conditions resulted in an improvement in the expression level, and approximately 45 U/L of laccase was functionally secreted in the culture. The recombinant laccase was found to be a heavily hypermannosylated glycoprotein, and the molecular weight of the carbohydrate chain was approximately 60 kDa. These hypermannosylated glycans lowered the substrate affinity, but the optimum pH and thermo-stability were not changed by these hypermannosylated glycans. This functional expression system described here will aid in molecular evolutionary studies conducted to generate new variants of laccase. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Novel image cytometric method for detection of physiological and metabolic changes in Saccharomyces cerevisiae.

    PubMed

    Chan, Leo L; Kury, Alexandria; Wilkinson, Alisha; Berkes, Charlotte; Pirani, Alnoor

    2012-11-01

    The studying and monitoring of physiological and metabolic changes in Saccharomyces cerevisiae (S. cerevisiae) has been a key research area for the brewing, baking, and biofuels industries, which rely on these economically important yeasts to produce their products. Specifically for breweries, physiological and metabolic parameters such as viability, vitality, glycogen, neutral lipid, and trehalose content can be measured to better understand the status of S. cerevisiae during fermentation. Traditionally, these physiological and metabolic changes can be qualitatively observed using fluorescence microscopy or flow cytometry for quantitative fluorescence analysis of fluorescently labeled cellular components associated with each parameter. However, both methods pose known challenges to the end-users. Specifically, conventional fluorescent microscopes lack automation and fluorescence analysis capabilities to quantitatively analyze large numbers of cells. Although flow cytometry is suitable for quantitative analysis of tens of thousands of fluorescently labeled cells, the instruments require a considerable amount of maintenance, highly trained technicians, and the system is relatively expensive to both purchase and maintain. In this work, we demonstrate the first use of Cellometer Vision for the kinetic detection and analysis of vitality, glycogen, neutral lipid, and trehalose content of S. cerevisiae. This method provides an important research tool for large and small breweries to study and monitor these physiological behaviors during production, which can improve fermentation conditions to produce consistent and higher-quality products.

  16. [Surface display of phytase on Saccharomyces cerevisiae for efficient bioethanol production from corn starch].

    PubMed

    Xiao, Yan; Chen, Xianzhong; Shen, Wei; Yang, Haiquan; Fan, You

    2015-12-01

    Production of bioethanol using starch as raw material has become a very prominent technology. However, phytate in the raw material not only decreases ethanol production efficiency, but also increases phosphorus discharge. In this study, to decrease phytate content in an ethanol fermentationprocess, Saccharomyces cerevisiae was engineered forheterologous expression of phytase on the cell surface. The phy gene encoding phytase gene was fused with the C-terminal-half region of α-agglutinin and then inserted downstream of the secretion signal gene, to produce a yeast surface-display expression vector pMGK-AG-phy, which was then transformed into S. cerevisiae. The recombinant yeast strain, PHY, successfully displayed phytase on the surface of cells producing 6.4 U/g wet cells and its properties were further characterized. The growthrate and ethanol production of the PHY strain were faster than the parent S. cerevisiae strain in the fermentation medium by simultaneous saccharification and fermentation. Moreover, the phytate concentration decreased by 91% in dry vinasse compared to the control. In summary, we constructed recombinant S. cerevisiae strain displaying phytase on the cell surface, which could effectively reduce the content of phytate, improve the utilization value of vinasse and reduce the discharge of phosphorus. The strain reported here represents a useful novel engineering platform for developing an environment-friendly system for bioethanol production from a corn substrate.

  17. Water-Transfer Slows Aging in Saccharomyces cerevisiae

    PubMed Central

    Cohen, Aviv; Weindling, Esther; Rabinovich, Efrat; Nachman, Iftach; Fuchs, Shai; Chuartzman, Silvia; Gal, Lihi; Schuldiner, Maya; Bar-Nun, Shoshana

    2016-01-01

    Transferring Saccharomyces cerevisiae cells to water is known to extend their lifespan. However, it is unclear whether this lifespan extension is due to slowing the aging process or merely keeping old yeast alive. Here we show that in water-transferred yeast, the toxicity of polyQ proteins is decreased and the aging biomarker 47Q aggregates at a reduced rate and to a lesser extent. These beneficial effects of water-transfer could not be reproduced by diluting the growth medium and depended on de novo protein synthesis and proteasomes levels. Interestingly, we found that upon water-transfer 27 proteins are downregulated, 4 proteins are upregulated and 81 proteins change their intracellular localization, hinting at an active genetic program enabling the lifespan extension. Furthermore, the aging-related deterioration of the heat shock response (HSR), the unfolded protein response (UPR) and the endoplasmic reticulum-associated protein degradation (ERAD), was largely prevented in water-transferred yeast, as the activities of these proteostatic network pathways remained nearly as robust as in young yeast. The characteristics of young yeast that are actively maintained upon water-transfer indicate that the extended lifespan is the outcome of slowing the rate of the aging process. PMID:26862897

  18. Histone H2A is required for normal centromere function in Saccharomyces cerevisiae

    PubMed Central

    Pinto, Inés; Winston, Fred

    2000-01-01

    Histones are structural and functional components of the eukaryotic chromosome, and their function is essential for normal cell cycle progression. In this work, we describe the characterization of two Saccharomyces cerevisiae cold-sensitive histone H2A mutants. Both mutants contain single amino acid replacements of residues predicted to be on the surface of the nucleosome and in close contact with DNA. We show that these H2A mutations cause an increase-in-ploidy phenotype, an increased rate of chromosome loss, and a defect in traversing the G2–M phase of the cell cycle. Moreover, these H2A mutations show genetic interactions with mutations in genes encoding kinetochore components. Finally, chromatin analysis of these H2A mutants has revealed an altered centromeric chromatin structure. Taken together, these results strongly suggest that histone H2A is required for proper centromere–kinetochore function during chromosome segregation. PMID:10747028

  19. Nucleotide sequence of the Saccharomyces cerevisiae PUT4 proline-permease-encoding gene: similarities between CAN1, HIP1 and PUT4 permeases.

    PubMed

    Vandenbol, M; Jauniaux, J C; Grenson, M

    1989-11-15

    The complete nucleotide (nt) sequence of the PUT4 gene, whose product is required for high-affinity proline active transport in the yeast Saccharomyces cerevisiae, is presented. The sequence contains a single long open reading frame of 1881 nt, encoding a polypeptide with a calculated Mr of 68,795. The predicted protein is strongly hydrophobic and exhibits six potential glycosylation sites. Its hydropathy profile suggests the presence of twelve membrane-spanning regions flanked by hydrophilic N- and C-terminal domains. The N terminus does not resemble signal sequences found in secreted proteins. These features are characteristic of integral membrane proteins catalyzing translocation of ligands across cellular membranes. Protein sequence comparisons indicate strong resemblance to the arginine and histidine permeases of S. cerevisiae, but no marked sequence similarity to the proline permease of Escherichia coli or to other known prokaryotic or eukaryotic transport proteins. The strong similarity between the three yeast amino acid permeases suggests a common ancestor for the three proteins.

  20. Reconstitution of Saccharomyces cerevisiae DNA polymerase ε-dependent mismatch repair with purified proteins.

    PubMed

    Bowen, Nikki; Kolodner, Richard D

    2017-04-04

    Mammalian and Saccharomyces cerevisiae mismatch repair (MMR) proteins catalyze two MMR reactions in vitro. In one, mispair binding by either the MutS homolog 2 (Msh2)-MutS homolog 6 (Msh6) or the Msh2-MutS homolog 3 (Msh3) stimulates 5' to 3' excision by exonuclease 1 (Exo1) from a single-strand break 5' to the mispair, excising the mispair. In the other, Msh2-Msh6 or Msh2-Msh3 activate the MutL homolog 1 (Mlh1)-postmeiotic segregation 1 (Pms1) endonuclease in the presence of a mispair and a nick 3' to the mispair, to make nicks 5' to the mispair, allowing Exo1 to excise the mispair. DNA polymerase δ (Pol δ) is thought to catalyze DNA synthesis to fill in the gaps resulting from mispair excision. However, colocalization of the S. cerevisiae mispair recognition proteins with the replicative DNA polymerases during DNA replication has suggested that DNA polymerase ε (Pol ε) may also play a role in MMR. Here we describe the reconstitution of Pol ε-dependent MMR using S. cerevisiae proteins. A mixture of Msh2-Msh6 (or Msh2-Msh3), Exo1, RPA, RFC-Δ1N, PCNA, and Pol ε was found to catalyze both short-patch and long-patch 5' nick-directed MMR of a substrate containing a +1 (+T) mispair. When the substrate contained a nick 3' to the mispair, a mixture of Msh2-Msh6 (or Msh2-Msh3), Exo1, RPA, RFC-Δ1N, PCNA, and Pol ε was found to catalyze an MMR reaction that required Mlh1-Pms1. These results demonstrate that Pol ε can act in eukaryotic MMR in vitro.

  1. Changing flux of xylose metabolites by altering expression of xylose reductase and xylitol dehydrogenase in recombinant Saccharomyces cerevisiae

    Treesearch

    Yong-Su Jin; Thomas W. Jeffries

    2003-01-01

    We changed the fluxes of xylose metabolites in recombinant Saccharomyces cerevisiae by manipulating expression of Pichia stipitis genes(XYL1 and XYL2) coding for xylose reductase (XR) and xylitol dehydrogenase (XDH), respectively. XYL1 copy number was kept constant by integrating it into the chromosome. Copy numbers of XYL2 were varied either by integrating XYL2 into...

  2. [Saccharomyces cerevisiae fungemia in an elderly patient following probiotic treatment].

    PubMed

    Eren, Zehra; Gurol, Yeşim; Sonmezoglu, Meral; Eren, Hatice Seyma; Celik, Gülden; Kantarci, Gülçin

    2014-04-01

    Saccharomyces cerevisiae, known as baker's yeast, is also used as a probiotic agent to treat gastroenteritis by modulating the endogenous flora and immune system. However, since there have been increasing reports of fungemia due to S.cerevisiae and its subspecies S.boulardii, it is recommended that probiotics should be cautiously used in immunosuppressed patients, people with underlying diseases and low-birth weight babies. To emphasize this phenomenon, in this report, a case of S.cerevisiae fungemia developed in a patient given probiotic treatment for antibiotic-associated diarrhea, was presented. An 88-year-old female patient was admitted to our hospital with left hip pain, hypotension, and confusion. Her medical history included hypertension, chronic renal failure, left knee replacement surgery, and recurrent urinary tract infections due to neurogenic bladder. She was transferred to the intensive care unit with the diagnosis of urosepsis. After obtaining blood and urine samples for culture, empirical meropenem (2 x 500 mg) and linezolid (1 x 600 mg) treatment were administered. A central venous catheter (CVC) was inserted and after one day of inotropic support, her hemodynamic parameters were stabilized. The urine culture obtained on admission yielded extended-spectrum beta-lactamase-producing Klebsiella pneumoniae and Escherichia coli. Urine culture was repeated after three days and no bacteria were isolated. On the 4th day of admission she developed diarrhea. Toxin A/B tests for Clostridium difficile were negative. To relieve diarrhea, S.boulardii (Reflor 250 mg capsules, Sanofi Aventis, Turkey) was administered twice a day, without opening capsules. Two days later, her C-reactive protein (CRP) level increased from 23.2 mg/L to 100 mg/L without fever. Her blood culture taken from the CVC yielded S.cerevisiae. Linezolid and meropenem therapies were stopped on the 13th and 14th days, respectively, while prophylactic fluconazole therapy was replaced with

  3. Volatile profiles and chromatic characteristics of red wines produced with Starmerella bacillaris and Saccharomyces cerevisiae.

    PubMed

    Englezos, Vasileios; Rantsiou, Kalliopi; Cravero, Francesco; Torchio, Fabrizio; Giacosa, Simone; Ortiz-Julien, Anne; Gerbi, Vincenzo; Rolle, Luca; Cocolin, Luca

    2018-07-01

    The use of mixed fermentations with Starmerella bacillaris and Saccharomyces cerevisiae is gaining attention in recent years due to their ability to modulate the metabolites production of enological interest. In the present study, four of the most popular planted red grape varieties (Cabernet sauvignon, Merlot, Pinot noir and Shiraz) were fermented using the aforementioned species and two different inoculation protocols (inoculation of S. cerevisiae after 24 and 48 h from the Starm. bacillaris inoculation), in order to evaluate their impact on the volatile composition and chromatic characteristics of wines. Analysis from chemical composition showed that titratable acidity and glycerol content exhibited marked differences among wines after fermentation. For volatile compounds, mixed fermented wines using an inoculation delay of 48 h led to reduction of volatile compounds (mainly esters). A shorter 24 h delay produced wines with higher values of color intensity than pure fermented wines. The differences observed between the inoculation protocols can be explained by the growth dynamics of both species during fermentation. These findings suggest that mixed fermentations posed a great potential in reducing metabolites which are considered negative for wine quality (mainly ethyl acetate and volatile fatty acids) and with an improvement of the chromatic profile of the wines. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Crystal structures of Hsp104 N-terminal domains from Saccharomyces cerevisiae and Candida albicans suggest the mechanism for the function of Hsp104 in dissolving prions

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

    Wang, Peng; Li, Jingzhi; Weaver, Clarissa

    Hsp104 is a yeast member of the Hsp100 family which functions as a molecular chaperone to disaggregate misfolded polypeptides. To understand the mechanism by which the Hsp104 N-terminal domain (NTD) interacts with its peptide substrates, crystal structures of the Hsp104 NTDs fromSaccharomyces cerevisiae(ScHsp104NTD) andCandida albicans(CaHsp104NTD) have been determined at high resolution. The structures of ScHsp104NTD and CaHsp104NTD reveal that the yeast Hsp104 NTD may utilize a conserved putative peptide-binding groove to interact with misfolded polypeptides. In the crystal structures ScHsp104NTD forms a homodimer, while CaHsp104NTD exists as a monomer. The consecutive residues Gln105, Gln106 and Lys107, and Lys141 around themore » putative peptide-binding groove mediate the monomer–monomer interactions within the ScHsp104NTD homodimer. Dimer formation by ScHsp104NTD suggests that the Hsp104 NTD may specifically interact with polyQ regions of prion-prone proteins. The data may reveal the mechanism by which Hsp104 NTD functions to suppress and/or dissolve prions.« less

  5. The Use of Mixed Populations of Saccharomyces cerevisiae and S. kudriavzevii to Reduce Ethanol Content in Wine: Limited Aeration, Inoculum Proportions, and Sequential Inoculation

    PubMed Central

    Alonso-del-Real, Javier; Contreras-Ruiz, Alba; Castiglioni, Gabriel L.; Barrio, Eladio; Querol, Amparo

    2017-01-01

    Saccharomyces cerevisiae is the most widespread microorganism responsible for wine alcoholic fermentation. Nevertheless, the wine industry is currently facing new challenges, some of them associate with climate change, which have a negative effect on ethanol content and wine quality. Numerous and varied strategies have been carried out to overcome these concerns. From a biotechnological point of view, the use of alternative non-Saccharomyces yeasts, yielding lower ethanol concentrations and sometimes giving rise to new and interesting aroma, is one of the trendiest approaches. However, S. cerevisiae usually outcompetes other Saccharomyces species due to its better adaptation to the fermentative environment. For this reason, we studied for the first time the use of a Saccharomyces kudriavzevii strain, CR85, for co-inoculations at increasing proportions and sequential inoculations, as well as the effect of aeration, to improve its fermentation performance in order to obtain wines with an ethanol yield reduction. An enhanced competitive performance of S. kudriavzevii CR85 was observed when it represented 90% of the cells present in the inoculum. Furthermore, airflow supply of 20 VVH to the fermentation synergistically improved CR85 endurance and, interestingly, a significant ethanol concentration reduction was achieved. PMID:29118746

  6. The Use of Mixed Populations of Saccharomyces cerevisiae and S. kudriavzevii to Reduce Ethanol Content in Wine: Limited Aeration, Inoculum Proportions, and Sequential Inoculation.

    PubMed

    Alonso-Del-Real, Javier; Contreras-Ruiz, Alba; Castiglioni, Gabriel L; Barrio, Eladio; Querol, Amparo

    2017-01-01

    Saccharomyces cerevisiae is the most widespread microorganism responsible for wine alcoholic fermentation. Nevertheless, the wine industry is currently facing new challenges, some of them associate with climate change, which have a negative effect on ethanol content and wine quality. Numerous and varied strategies have been carried out to overcome these concerns. From a biotechnological point of view, the use of alternative non- Saccharomyces yeasts, yielding lower ethanol concentrations and sometimes giving rise to new and interesting aroma, is one of the trendiest approaches. However, S. cerevisiae usually outcompetes other Saccharomyces species due to its better adaptation to the fermentative environment. For this reason, we studied for the first time the use of a Saccharomyces kudriavzevii strain, CR85, for co-inoculations at increasing proportions and sequential inoculations, as well as the effect of aeration, to improve its fermentation performance in order to obtain wines with an ethanol yield reduction. An enhanced competitive performance of S. kudriavzevii CR85 was observed when it represented 90% of the cells present in the inoculum. Furthermore, airflow supply of 20 VVH to the fermentation synergistically improved CR85 endurance and, interestingly, a significant ethanol concentration reduction was achieved.

  7. Cell cycle phases in the unequal mother/daughter cell cycles of Saccharomyces cerevisiae.

    PubMed

    Brewer, B J; Chlebowicz-Sledziewska, E; Fangman, W L

    1984-11-01

    During cell division in the yeast Saccharomyces cerevisiae mother cells produce buds (daughter cells) which are smaller and have longer cell cycles. We performed experiments to compare the lengths of cell cycle phases in mothers and daughters. As anticipated from earlier indirect observations, the longer cell cycle time of daughter cells is accounted for by a longer G1 interval. The S-phase and the G2-phase are of the same duration in mother and daughter cells. An analysis of five isogenic strains shows that cell cycle phase lengths are independent of cell ploidy and mating type.

  8. Frameshift Suppression in SACCHAROMYCES CEREVISIAE. V. Isolation and Genetic Properties of Nongroup-Specific Suppressors

    PubMed Central

    Culbertson, Michael R.; Gaber, Richard F.; Cummins, Claudia M.

    1982-01-01

    Two classes of frameshift suppressors distributed at 22 different loci were identified in previous studies in the yeast Saccharomyces cerevisiae. These suppressors exhibited allele-specific suppression of +1 G:C insertion mutations in either glycine or proline codons, designated as group II and group III frameshift mutations, respectively. Genes corresponding to representative suppressors of each group have been shown to encode altered glycine or proline tRNAs containing four base anticodons.—This communication reports the existence of a third class of frameshift suppressor that exhibits a wider range in specificity of suppression. The suppressors map at three loci, suf12, suf13, and suf14, which are located on chromosomes IV, XV, and XIV, respectively. The phenotypes of these suppressors suggest that suppression may be mediated by genes other than those encoding the primary structure of glycine or proline tRNAs. PMID:6757053

  9. Characterization of Alcohol-induced Filamentous Growth in Saccharomyces cerevisiae

    PubMed Central

    Lorenz, Michael C.; Cutler, N. Shane; Heitman, Joseph

    2000-01-01

    Diploid cells of the budding yeast Saccharomyces cerevisiae starved for nitrogen differentiate into a filamentous growth form. Poor carbon sources such as starches can also stimulate filamentation, whereas haploid cells undergo a similar invasive growth response in rich medium. Previous work has demonstrated a role for various alcohols, by-products of amino acid metabolism, in altering cellular morphology. We found that several alcohols, notably isoamyl alcohol and 1-butanol, stimulate filamentous growth in haploid cells in which this differentiation is normally repressed. Butanol also induces cell elongation and changes in budding pattern, leading to a pseudohyphal morphology, even in liquid medium. The filamentous colony morphology and cell elongation require elements of the pheromone-responsive MAPK cascade and TEC1, whereas components of the nutrient-sensing machinery, such as MEP2, GPA2, and GPR1, do not affect this phenomenon. A screen for 1-butanol–insensitive mutants identified additional proteins that regulate polarized growth (BUD8, BEM1, BEM4, and FIG1), mitochondrial function (MSM1, MRP21, and HMI1), and a transcriptional regulator (CHD1). Furthermore, we have also found that ethanol stimulates hyperfilamentation in diploid cells, again in a MAPK-dependent manner. Together, these results suggest that yeast may sense a combination of nutrient limitation and metabolic by-products to regulate differentiation. PMID:10637301

  10. The histidine permease gene (HIP1) of Saccharomyces cerevisiae.

    PubMed

    Tanaka, J; Fink, G R

    1985-01-01

    The histidine-specific permease gene (HIP1) of Saccharomyces cerevisiae has been mapped, cloned, and sequenced. The HIP1 gene maps to the right arm of chromosome VII, approx. 11 cM distal to the ADE3 gene. The gene was isolated as an 8.6-kb BamHI-Sau3A fragment by complementation of the histidine-specific permease deficiency in recipient yeast cells. We sequenced a 2.4-kb subfragment of this BamHI-Sau3A fragment containing the HIP1 gene and identified a 1596-bp open reading frame (ORF). We confirmed the assignment of the 1596-bp ORF as the HIP1 coding sequence by sequencing a hip1 nonsense mutation. Analysis of the amino acid (aa) sequence of the HIP1 gene reveals several hydrophobic stretches, but shows no obvious N-terminal signal peptide. We have constructed a deletion of the HIP1 gene in vitro and replaced the wild-type copy of the gene with this deletion. The hip1 deletion mutant can grow when it is supplemented with 30 mM histidine, 50 times the amount required for the growth of HIP1 cells. Revertants of this deletion mutant able to grow on a normal level of histidine arise by mutation in unlinked genes. Both these observations suggest that there are additional, low-affinity pathways for histidine uptake.

  11. Saccharomyces cerevisiae Mob1p Is Required for Cytokinesis and Mitotic Exit

    PubMed Central

    Luca, Francis C.; Mody, Manali; Kurischko, Cornelia; Roof, David M.; Giddings, Thomas H.; Winey, Mark

    2001-01-01

    The Saccharomyces cerevisiae mitotic exit network (MEN) is a conserved set of genes that mediate the transition from mitosis to G1 by regulating mitotic cyclin degradation and the inactivation of cyclin-dependent kinase (CDK). Here, we demonstrate that, in addition to mitotic exit, S. cerevisiae MEN gene MOB1 is required for cytokinesis and cell separation. The cytokinesis defect was evident in mob1 mutants under conditions in which there was no mitotic-exit defect. Observation of live cells showed that yeast myosin II, Myo1p, was present in the contractile ring at the bud neck but that the ring failed to contract and disassemble. The cytokinesis defect persisted for several mitotic cycles, resulting in chains of cells with correctly segregated nuclei but with uncontracted actomyosin rings. The cytokinesis proteins Cdc3p (a septin), actin, and Iqg1p/ Cyk1p (an IQGAP-like protein) appeared to correctly localize in mob1 mutants, suggesting that MOB1 functions subsequent to actomyosin ring assembly. We also examined the subcellular distribution of Mob1p during the cell cycle and found that Mob1p first localized to the spindle pole bodies during mid-anaphase and then localized to a ring at the bud neck just before and during cytokinesis. Localization of Mob1p to the bud neck required CDC3, MEN genes CDC5, CDC14, CDC15, and DBF2, and spindle pole body gene NUD1 but was independent of MYO1. The localization of Mob1p to both spindle poles was abolished in cdc15 and nud1 mutants and was perturbed in cdc5 and cdc14 mutants. These results suggest that the MEN functions during the mitosis-to-G1 transition to control cyclin-CDK inactivation and cytokinesis. PMID:11564880

  12. Systems biology and pathway engineering enable Saccharomyces cerevisiae to utilize C-5 and C-6 sugars simultaneously for cellulosic ethanol production

    USDA-ARS?s Scientific Manuscript database

    Saccharomyces cerevisiae is a traditional industrial workhorse for ethanol production. However, conventional ethanologenic yeast is superior in fermentation of hexose sugars (C-6) such as glucose but unable to utilize pentose sugars (C-5) such as xylose richly embedded in lignocellulosic biomass. In...

  13. Effect of citrus pulp on the viability of the probiotic Saccharomyces cerevisiae bouldarii (Levucell) and subsequent effects in presence of pathogens

    USDA-ARS?s Scientific Manuscript database

    The probiotic Saccharomyces cerevisiae subtype boulardii (i.e., Levucell) is commonly provided to weaned and nursing sows to promote intestinal health through limiting the colonization of pathogens. Recent research from our group identified that supplementation of this probiotic to feed containing t...

  14. Factors involved in anaerobic growth of Saccharomyces cerevisiae.

    PubMed

    Ishtar Snoek, I S; Yde Steensma, H

    2007-01-01

    Life in the absence of molecular oxygen requires several adaptations. Traditionally, the switch from respiratory metabolism to fermentation has attracted much attention in Saccharomyces cerevisiae, as this is the basis for the use of this yeast in the production of alcohol and in baking. It has also been clear that under anaerobic conditions the yeast is not able to synthesize sterols and unsaturated fatty acids and that for anaerobic growth these have to be added to the media. More recently it has been found that many more factors play a role. Several other biosynthetic reactions also require molecular oxygen and the yeast must have alternatives for these. In addition, the composition of the cell wall and cell membrane show major differences when aerobic and anaerobic cells are compared. All these changes are reflected by the observation that the transcription of more than 500 genes changes significantly between aerobically and anaerobically growing cultures. In this review we will give an overview of the factors that play a role in the survival in the absence of molecular oxygen. Copyright (c) 2007 John Wiley & Sons, Ltd.

  15. Nuclear Mitochondrial DNA Activates Replication in Saccharomyces cerevisiae

    PubMed Central

    Chatre, Laurent; Ricchetti, Miria

    2011-01-01

    The nuclear genome of eukaryotes is colonized by DNA fragments of mitochondrial origin, called NUMTs. These insertions have been associated with a variety of germ-line diseases in humans. The significance of this uptake of potentially dangerous sequences into the nuclear genome is unclear. Here we provide functional evidence that sequences of mitochondrial origin promote nuclear DNA replication in Saccharomyces cerevisiae. We show that NUMTs are rich in key autonomously replicating sequence (ARS) consensus motifs, whose mutation results in the reduction or loss of DNA replication activity. Furthermore, 2D-gel analysis of the mrc1 mutant exposed to hydroxyurea shows that several NUMTs function as late chromosomal origins. We also show that NUMTs located close to or within ARS provide key sequence elements for replication. Thus NUMTs can act as independent origins, when inserted in an appropriate genomic context or affect the efficiency of pre-existing origins. These findings show that migratory mitochondrial DNAs can impact on the replication of the nuclear region they are inserted in. PMID:21408151

  16. Nuclear mitochondrial DNA activates replication in Saccharomyces cerevisiae.

    PubMed

    Chatre, Laurent; Ricchetti, Miria

    2011-03-08

    The nuclear genome of eukaryotes is colonized by DNA fragments of mitochondrial origin, called NUMTs. These insertions have been associated with a variety of germ-line diseases in humans. The significance of this uptake of potentially dangerous sequences into the nuclear genome is unclear. Here we provide functional evidence that sequences of mitochondrial origin promote nuclear DNA replication in Saccharomyces cerevisiae. We show that NUMTs are rich in key autonomously replicating sequence (ARS) consensus motifs, whose mutation results in the reduction or loss of DNA replication activity. Furthermore, 2D-gel analysis of the mrc1 mutant exposed to hydroxyurea shows that several NUMTs function as late chromosomal origins. We also show that NUMTs located close to or within ARS provide key sequence elements for replication. Thus NUMTs can act as independent origins, when inserted in an appropriate genomic context or affect the efficiency of pre-existing origins. These findings show that migratory mitochondrial DNAs can impact on the replication of the nuclear region they are inserted in.

  17. De novo biosynthesis of anthocyanins in Saccharomyces cerevisiae.

    PubMed

    Eichenberger, Michael; Hansson, Anders; Fischer, David; Dürr, Lara; Naesby, Michael

    2018-06-01

    Anthocyanins (ACNs) are plant secondary metabolites responsible for most of the red, purple and blue colors of flowers, fruits and vegetables. They are increasingly used in the food and beverage industry as natural alternative to artificial colorants. Production of these compounds by fermentation of microorganisms would provide an attractive alternative. In this study, Saccharomyces cerevisiae was engineered for de novo production of the three basic anthocyanins, as well as the three main trans-flavan-3-ols. Enzymes from different plant sources were screened and efficient variants found for most steps of the biosynthetic pathway. However, the anthocyanidin synthase was identified as a major obstacle to efficient production. In yeast, this enzyme converts the majority of its natural substrates leucoanthocyanidins into the off-pathway flavonols. Nonetheless, de novo biosynthesis of ACNs was shown for the first time in yeast and for the first time in a single microorganism. It provides a framework for optimizing the activity of anthocyanidin synthase and represents an important step towards sustainable industrial production of these highly relevant molecules in yeast.

  18. Carboxylic Acids Plasma Membrane Transporters in Saccharomyces cerevisiae.

    PubMed

    Casal, Margarida; Queirós, Odília; Talaia, Gabriel; Ribas, David; Paiva, Sandra

    2016-01-01

    This chapter covers the functionally characterized plasma membrane carboxylic acids transporters Jen1, Ady2, Fps1 and Pdr12 in the yeast Saccharomyces cerevisiae, addressing also their homologues in other microorganisms, as filamentous fungi and bacteria. Carboxylic acids can either be transported into the cells, to be used as nutrients, or extruded in response to acid stress conditions. The secondary active transporters Jen1 and Ady2 can mediate the uptake of the anionic form of these substrates by a H(+)-symport mechanism. The undissociated form of carboxylic acids is lipid-soluble, crossing the plasma membrane by simple diffusion. Furthermore, acetic acid can also be transported by facilitated diffusion via Fps1 channel. At the cytoplasmic physiological pH, the anionic form of the acid prevails and it can be exported by the Pdr12 pump. This review will highlight the mechanisms involving carboxylic acids transporters, and the way they operate according to the yeast cell response to environmental changes, as carbon source availability, extracellular pH and acid stress conditions.

  19. Oxygen requirements of yeasts. [Saccharomyces cerevisiae; Candida tropicalis

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

    Visser, W.; Scheffers, W.A.; Batenburg-Van Der Vegte, W.H.

    1990-12-01

    Type species of 75 yeast genera were examined for their ability to grow anaerobically in complex and mineral media. To define anaerobic conditions, we added a redox indicator, resazurin, to the media to determine low redox potentials. All strains tested were capable of fermenting glucose to ethanol in oxygen-limited shake-flask cultures, even those of species generally regarded as nonfermentative. However, only 23% of the yeast species tested grew under anaerobic conditions. A comparative study with a number of selected strains revealed that Saccharomyces cerevisiae stands out as a yeast capable of rapid growth at low redox potentials. Other yeasts, suchmore » as Torulaspora delbrueckii and Candida tropicalis, grew poorly ({mu}{sub max}, 0.03 and 0.05 h{sup {minus}1}, respectively) under anaerobic conditions in mineral medium supplemented with Tween 80 and ergosterol. The latter organisms grew rapidly under oxygen limitation and then displayed a high rate of alcoholic fermentation. It can be concluded that these yeasts have hitherto-unidentified oxygen requirements for growth.« less

  20. Development of stress tolerant Saccharomyces cerevisiae strains by metabolic engineering: New aspects from cell flocculation and zinc supplementation.

    PubMed

    Cheng, Cheng; Zhang, Mingming; Xue, Chuang; Bai, Fengwu; Zhao, Xinqing

    2017-02-01

    Budding yeast Saccharomyces cerevisiae is widely studied for the production of biofuels from lignocellulosic biomass. However, economic production is currently challenged by the repression of cell growth and compromised fermentation performance of S. cerevisiae strains in the presence of various environmental stresses, including toxic level of final products, inhibitory compounds released from the pretreatment of cellulosic feedstocks, high temperature, and so on. Therefore, it is important to improve stress tolerance of S. cerevisiae to these stressful conditions to achieve efficient and economic production. In this review, the latest advances on development of stress tolerant S. cerevisiae strains are summarized, with the emphasis on the impact of cell flocculation and zinc addition. It was found that cell flocculation affected ethanol tolerance and acetic acid tolerance of S. cerevisiae, and addition of zinc to a suitable level improved stress tolerance of yeast cells to ethanol, high temperature and acetic acid. Further studies on the underlying mechanisms by which cell flocculation and zinc status affect stress tolerance will not only enrich our knowledge on stress response and tolerance mechanisms of S. cerevisiae, but also provide novel metabolic engineering strategies to develop robust yeast strains for biofuels production. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  1. Extensive Copy Number Variation in Fermentation-Related Genes Among Saccharomyces cerevisiae Wine Strains.

    PubMed

    Steenwyk, Jacob; Rokas, Antonis

    2017-05-05

    Due to the importance of Saccharomyces cerevisiae in wine-making, the genomic variation of wine yeast strains has been extensively studied. One of the major insights stemming from these studies is that wine yeast strains harbor low levels of genetic diversity in the form of single nucleotide polymorphisms (SNPs). Genomic structural variants, such as copy number (CN) variants, are another major type of variation segregating in natural populations. To test whether genetic diversity in CN variation is also low across wine yeast strains, we examined genome-wide levels of CN variation in 132 whole-genome sequences of S. cerevisiae wine strains. We found an average of 97.8 CN variable regions (CNVRs) affecting ∼4% of the genome per strain. Using two different measures of CN diversity, we found that gene families involved in fermentation-related processes such as copper resistance ( CUP ), flocculation ( FLO ), and glucose metabolism ( HXT ), as well as the SNO gene family whose members are expressed before or during the diauxic shift, showed substantial CN diversity across the 132 strains examined. Importantly, these same gene families have been shown, through comparative transcriptomic and functional assays, to be associated with adaptation to the wine fermentation environment. Our results suggest that CN variation is a substantial contributor to the genomic diversity of wine yeast strains, and identify several candidate loci whose levels of CN variation may affect the adaptation and performance of wine yeast strains during fermentation. Copyright © 2017 Steenwyk and Rokas.

  2. L-carnosine affects the growth of Saccharomyces cerevisiae in a metabolism-dependent manner.

    PubMed

    Cartwright, Stephanie P; Bill, Roslyn M; Hipkiss, Alan R

    2012-01-01

    The dipeptide L-carnosine (β-alanyl-L-histidine) has been described as enigmatic: it inhibits growth of cancer cells but delays senescence in cultured human fibroblasts and extends the lifespan of male fruit flies. In an attempt to understand these observations, the effects of L-carnosine on the model eukaryote, Saccharomyces cerevisiae, were examined on account of its unique metabolic properties; S. cerevisiae can respire aerobically, but like some tumor cells, it can also exhibit a metabolism in which aerobic respiration is down regulated. L-Carnosine exhibited both inhibitory and stimulatory effects on yeast cells, dependent upon the carbon source in the growth medium. When yeast cells were not reliant on oxidative phosphorylation for energy generation (e.g. when grown on a fermentable carbon source such as 2% glucose), 10-30 mM L-carnosine slowed growth rates in a dose-dependent manner and increased cell death by up to 17%. In contrast, in media containing a non-fermentable carbon source in which yeast are dependent on aerobic respiration (e.g. 2% glycerol), L-carnosine did not provoke cell death. This latter observation was confirmed in the respiratory yeast, Pichia pastoris. Moreover, when deletion strains in the yeast nutrient-sensing pathway were treated with L-carnosine, the cells showed resistance to its inhibitory effects. These findings suggest that L-carnosine affects cells in a metabolism-dependent manner and provide a rationale for its effects on different cell types.

  3. Ectopic recombination between Ty elements in Saccharomyces cerevisiae is not induced by DNA damage.

    PubMed

    Parket, A; Kupiec, M

    1992-10-01

    Mitotic recombination is increased when cells are treated with a variety of physical and chemical agents that cause damage to their DNA. We show here, using Saccharomyces cerevisiae strains that carry marked Ty elements, that recombination between members of this family of retrotransposons is not increased by UV irradiation or by treatment with the radiomimetic drug methyl methanesulfonate. Both ectopic recombination and mutation events were elevated by these agents for non-Ty sequences in the same strain. We discuss possible mechanisms that can prevent the induction of recombination between Ty elements.

  4. Ethylene production in relation to nitrogen metabolism in Saccharomyces cerevisiae.

    PubMed

    Johansson, Nina; Persson, Karl O; Quehl, Paul; Norbeck, Joakim; Larsson, Christer

    2014-11-01

    We have previously shown that ethylene production in Saccharomyces cerevisiae expressing the ethylene-forming enzyme (EFE) from Pseudomonas syringae is strongly influenced by variations in the mode of cultivation as well as the choice of nitrogen source. Here, we have studied the influence of nitrogen metabolism on the production of ethylene further. Using ammonium, glutamate, glutamate/arginine, and arginine as nitrogen sources, it was found that glutamate (with or without arginine) correlates with a high ethylene production, most likely linked to an observed increase in 2-oxoglutarate levels. Arginine as a sole nitrogen source caused a reduced ethylene production. A reduction of arginine levels, accomplished using an arginine auxotrophic ARG4-deletion strain in the presence of limiting amounts of arginine or through CAR1 overexpression, did however not correlate with an increased ethylene production. As expected, arginine was necessary for ethylene production as ethylene production in the ARG4-deletion strain ceased at the time when arginine was depleted. In conclusion, our data suggest that high levels of 2-oxoglutarate and a limited amount of arginine are required for successful ethylene production in yeast. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  5. Recycling Carbon Dioxide during Xylose Fermentation by Engineered Saccharomyces cerevisiae.

    PubMed

    Xia, Peng-Fei; Zhang, Guo-Chang; Walker, Berkley; Seo, Seung-Oh; Kwak, Suryang; Liu, Jing-Jing; Kim, Heejin; Ort, Donald R; Wang, Shu-Guang; Jin, Yong-Su

    2017-02-17

    Global climate change caused by the emission of anthropogenic greenhouse gases (GHGs) is a grand challenge to humanity. To alleviate the trend, the consumption of fossil fuels needs to be largely reduced and alternative energy technologies capable of controlling GHG emissions are anticipated. In this study, we introduced a synthetic reductive pentose phosphate pathway (rPPP) into a xylose-fermenting Saccharomyces cerevisiae strain SR8 to achieve simultaneous lignocellulosic bioethanol production and carbon dioxide recycling. Specifically, ribulose-1,5-bisphosphate carboxylase/oxygenase from Rhodospirillum rubrum and phosphoribulokinase from Spinacia oleracea were introduced into the SR8 strain. The resulting strain with the synthetic rPPP was able to exhibit a higher yield of ethanol and lower yields of byproducts (xylitol and glycerol) than a control strain. In addition, the reduced release of carbon dioxide by the engineered strain was observed during xylose fermentation, suggesting that the carbon dioxide generated by pyruvate decarboxylase was partially reassimilated through the synthetic rPPP. These results demonstrated that recycling of carbon dioxide from the ethanol fermentation pathway in yeast can be achieved during lignocellulosic bioethanol production through a synthetic carbon conservative metabolic pathway. This strategy has a great potential to alleviate GHG emissions during the production of second-generation ethanol.

  6. HOL1 mutations confer novel ion transport in Saccharomyces cerevisiae.

    PubMed Central

    Gaber, R F; Kielland-Brandt, M C; Fink, G R

    1990-01-01

    Saccharomyces cerevisiae histidine auxotrophs are unable to use L-histidinol as a source of histidine even when they have a functional histidinol dehydrogenase. Mutations in the hol1 gene permit growth of His- cells on histidinol by enhancing the ability of cells to take up histidinol from the medium. Second-site mutations linked to HOL1-1 further increase histidinol uptake. HOL1 double mutants and, to a lesser extent, HOL1-1 single mutants show hypersensitivity to specific cations added to the growth medium, including Na+, Li+, Cs+, Be2+, guanidinium ion, and histidinol, but not K+, Rb+, Ca2+, or Mg2+. The Na(+)-hypersensitive phenotype is correlated with increased uptake and accumulation of this ion. The HOL1-1-101 gene was cloned and used to generate a viable haploid strain containing a hol1 deletion mutation (hol1 delta). The uptake of cations, the dominance of the mutant alleles, and the relative inability of hol1 delta cells to take up histidinol or Na+ suggest that hol1 encodes an ion transporter. The novel pattern of ion transport conferred by HOL1-1 and HOL1-1-101 mutants may be explained by reduced selectivity for the permeant ions. Images PMID:2405251

  7. Roles of Catalase and Trehalose in the Protection from Hydrogen Peroxide Toxicity in Saccharomyces cerevisiae.

    PubMed

    Nishimoto, Takuto; Watanabe, Takeru; Furuta, Masakazu; Kataoka, Michihiko; Kishida, Masao

    2016-01-01

    The roles of catalase and trehalose in Saccharomyces cerevisiae subject to hydrogen peroxide (H2O2) treatment were examined by measuring the catalase activity and intracellular trehalose levels in mutants lacking catalase or trehalose synthetase. Intracellular trehalose was elevated but the survival rate after H2O2 treatment remained low in mutants with deletion of the Catalase T gene. On the other hand, deletion of the trehalose synthetase gene increased the catalase activity in mutated yeast to levels higher than those in the wild-type strain, and these mutants exhibited some degree of tolerance to H2O2 treatment. These results suggest that Catalase T is critical in the yeast response to oxidative damage caused by H2O2 treatment, but trehalose also plays a role in protection against H2O2 treatment.

  8. Bioethanol production performance of five recombinant strains of laboratory and industrial xylose-fermenting Saccharomyces cerevisiae.

    PubMed

    Matsushika, Akinori; Inoue, Hiroyuki; Murakami, Katsuji; Takimura, Osamu; Sawayama, Shigeki

    2009-04-01

    In this study, five recombinant Saccharomyces cerevisiae strains were compared for their xylose-fermenting ability. The most efficient xylose-to-ethanol fermentation was found by using the industrial strain MA-R4, in which the genes for xylose reductase and xylitol dehydrogenase from Pichia stipitis along with an endogenous xylulokinase gene were expressed by chromosomal integration of the flocculent yeast strain IR-2. The MA-R4 strain rapidly converted xylose to ethanol with a low xylitol yield. Furthermore, the MA-R4 strain had the highest ethanol production when fermenting not only a mixture of glucose and xylose, but also mixed sugars in the detoxified hydrolysate of wood chips. These results collectively suggest that MA-R4 may be a suitable recombinant strain for further study into large-scale ethanol production from mixed sugars present in lignocellulosic hydrolysates.

  9. Biosorption of strontium ions from simulated high-level liquid waste by living Saccharomyces cerevisiae.

    PubMed

    Qiu, Liang; Feng, Jundong; Dai, Yaodong; Chang, Shuquan

    2018-04-12

    In this study, the Saccharomyces cerevisiae (S. cerevisiae) was modified by γ-ray. The RNA-seq results reflect that the high γ-ray energies could change some gene fragments, such as deletion, recombination, and mutation. The biosorption of strontium ions (Sr 2+ ) to different types of S. cerevisiae (S. cerevisiae (K-0), modified S. cerevisiae (Y-7), and non-living S. cerevisiae (H-K)) from the simulated high-level liquid waste (S-HLLW) was assessed at different experimental conditions. The sorption experimental results show that, under an appropriate condition, γ-ray radiation can enhance its biosorption capacity slightly of Sr 2+ to S. cerevisiae. The maximum metal uptake and efficiency of Y-7 under S-HLLW were 11.656 mg g -1 and 37.91% at 32 h (wet weight), respectively. They decreased to 9.46 mg g -1 and 30.76% under radiation conditions. SEM-EDX and TEM analysis indicates that Sr 2+ was adsorbed both on the cellular surface and the inner parts of the cells. Our experimental results fit well to the Langmuir and Freundlich model isotherms (r 2  > 0.94), and the maximum biosorption capacity values reached q max  > 24.74 mg g -1 at 32 °C. Negative values of ΔG 0 and positive values of ΔH 0 were observed, indicating the spontaneous and endothermic nature of Sr 2+ biosorption on modified S. cerevisiae. The biosorption kinetics follow a pseudo-second-order equation at 32 °C (r 2  > 0.94). The desorption efficiency of Sr 2+ adsorbed onto Y-7 was 7.65 ± 0.52%, 76.51 ± 2.13%, and 65.62 ± 2.42% by deionized water, 1 M HCl, and 0.1 M EDTA-Na, respectively. However, they were lower than H-K (18.82, 83.32, and 73.32%). Our findings demonstrate that living S. cerevisiae (Y-7) is a promising sorbent material for the treatment of radioactive process streams.

  10. Saccharomyces cerevisiae possesses a stress-inducible glycyl-tRNA synthetase gene.

    PubMed

    Chen, Shun-Jia; Wu, Yi-Hua; Huang, Hsiao-Yun; Wang, Chien-Chia

    2012-01-01

    Aminoacyl-tRNA synthetases are a large family of housekeeping enzymes that are pivotal in protein translation and other vital cellular processes. Saccharomyces cerevisiae possesses two distinct nuclear glycyl-tRNA synthetase (GlyRS) genes, GRS1 and GRS2. GRS1 encodes both cytoplasmic and mitochondrial activities, while GRS2 is essentially silent and dispensable under normal conditions. We herein present evidence that expression of GRS2 was drastically induced upon heat shock, ethanol or hydrogen peroxide addition, and high pH, while expression of GRS1 was somewhat repressed under those conditions. In addition, GlyRS2 (the enzyme encoded by GRS2) had a higher protein stability and a lower K(M) value for yeast tRNA(Gly) under heat shock conditions than under normal conditions. Moreover, GRS2 rescued the growth defect of a GRS1 knockout strain when highly expressed by a strong promoter at 37 °C, but not at the optimal temperature of 30 °C. These results suggest that GRS2 is actually an inducible gene that may function to rescue the activity of GRS1 under stress conditions.

  11. POROSITY OF ISOLATED CELL WALLS OF SACCHAROMYCES CEREVISIAE AND BACILLUS MEGATERIUM.

    PubMed

    GERHARDT, P; JUDGE, J A

    1964-04-01

    Gerhardt, Philipp (The University of Michigan, Ann Arbor), and Jean A. Judge. Porosity of isolated cell walls of a yeast and a bacillus. J. Bacteriol. 87:945-951. 1964.-Decagram masses of cell walls were isolated from Saccharomyces cerevisiae and Bacillus megaterium; their porosity was examined by measuring the extent of uptake with polyethylene glycols and dextrans varying in molecular weight from 62 to 2,000,000. The results indicated that both walls are heteroporous. The near equality of extrapolated water-uptake values and determined moisture contents suggested that water in the cell walls is mainly free for distribution of solutes. Polymers with molecular weights of 4,500 and above were excluded by the yeast walls, and those with molecular weights of 57,000 were excluded by the bacillus walls; from these results, maximal openings of 36 and 107 A, respectively, were calculated. Electron micrographs of shadowed, stained, and sectioned walls revealed fine structure not inconsistent with heteroporosity, but the predicted openings were not seen. Altogether, in structure and permeability behavior, the cell walls were like a random meshwork of cross-linked macromolecular strands.

  12. COCOA (Theobroma cacao) Polyphenol-Rich Extract Increases the Chronological Lifespan of Saccharomyces cerevisiae.

    PubMed

    Baiges, I; Arola, L

    2016-01-01

    BACKGROUND: Saccharomyces cerevisiae is a model organism with conserved aging pathways. Yeast chronological lifespan experiments mimic the processes involved in human non-dividing tissues, such as the nervous system or skeletal muscle, and can speed up the search for biomolecules with potential anti-aging effects before proceeding to animal studies. OBJECTIVE: To test the effectiveness of a cocoa polyphenol-rich extract (CPE) in expanding the S. cerevisiae chronological lifespan in two conditions: in the stationary phase reached after glucose depletion and under severe caloric restriction. MEASUREMENTS: Using a high-throughput method, wild-type S. cerevisiae and its mitochondrial manganese-dependent superoxide dismutase null mutant (sod2Δ) were cultured in synthetic complete dextrose medium. After 2 days, 0, 5 and 20 mg/ml of CPE were added, and viability was measured throughout the stationary phase. The effects of the major components of CPE were also evaluated. To determine yeast lifespan under severe caloric restriction conditions, cultures were washed with water 24 h after the addition of 0 and 20 mg/ml of CPE, and viability was followed over time. RESULTS : CPE increased the chronological lifespan of S. cerevisiae during the stationary phase in a dose-dependent manner. A similar increase was also observed in (sod2Δ). None of the major CPE components (theobromine, caffeine, maltodextrin, (-)-epicatechin, (+)-catechin and procyanidin B2) was able to increase the yeast lifespan. CPE further increased the yeast lifespan under severe caloric restriction. CONCLUSION: CPE increases the chronological lifespan of S. cerevisiae through a SOD2-independent mechanism. The extract also extends yeast lifespan under severe caloric restriction conditions. The high-throughput assay used makes it possible to simply and rapidly test the efficacy of a large number of compounds on yeast aging, requiring only small amounts, and is thus a convenient screening assay to accelerate

  13. The effect of Saccharomyces cerevisiae on the stability of the herbicide glyphosate during bread leavening.

    PubMed

    Low, F L; Shaw, I C; Gerrard, J A

    2005-01-01

    To investigate the ability of baker's yeast (Saccharomyces cerevisiae) to degrade the herbicide glyphosate during the fermentation cycle of the breadmaking process. Aqueous glyphosate was added to bread ingredients and kneaded by commercially available breadmaking equipment into dough cultures. Cultures were incubated in the breadmaker throughout the fermentation cycle. The recovery of glyphosate levels following fermentation was determined, thus allowing an estimation of glyphosate degradation by yeast. It was shown, for the first time, that S. cerevisiae plays a role in metabolizing glyphosate during the fermentation stages of breadmaking. Approximately 21% was degraded within 1 h. As a result of projected increases in the glyphosate use on wheat and the role of bread as a dietary staple, this may contribute to more informed decisions being made relating to the use of glyphosate on glyphosate-resistant wheat, from a public health/regulatory perspective.

  14. Improving the performance of the Granulosis virus of Codling moth (Lepidoptera: Tortricideae) by adding the yeast Saccharomyces cerevisiae with sugar

    USDA-ARS?s Scientific Manuscript database

    Studies evaluated the effectiveness of adding Saccharomyces cerevisiae with brown cane sugar (sugar) to the codling moth granulosis virus, CpGV, to improve larval control of Cydia pomonella (L.), on apple. Neither the use of the yeast or sugar alone caused larval mortality greater than the water con...

  15. 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.

  16. Progress in terpene synthesis strategies through engineering of Saccharomyces cerevisiae.

    PubMed

    Paramasivan, Kalaivani; Mutturi, Sarma

    2017-12-01

    Terpenes are natural products with a remarkable diversity in their chemical structures and they hold a significant market share commercially owing to their distinct applications. These potential molecules are usually derived from terrestrial plants, marine and microbial sources. In vitro production of terpenes using plant tissue culture and plant metabolic engineering, although receiving some success, the complexity in downstream processing because of the interference of phenolics and product commercialization due to regulations that are significant concerns. Industrial workhorses' viz., Escherichia coli and Saccharomyces cerevisiae have become microorganisms to produce non-native terpenes in order to address critical issues such as demand-supply imbalance, sustainability and commercial viability. S. cerevisiae enjoys several advantages for synthesizing non-native terpenes with the most significant being the compatibility for expressing cytochrome P450 enzymes from plant origin. Moreover, achievement of high titers such as 40 g/l of amorphadiene, a sesquiterpene, boosts commercial interest and encourages the researchers to envisage both molecular and process strategies for developing yeast cell factories to produce these compounds. This review contains a brief consideration of existing strategies to engineer S. cerevisiae toward the synthesis of terpene molecules. Some of the common targets for synthesis of terpenes in S. cerevisiae are as follows: overexpression of tHMG1, ERG20, upc2-1 in case of all classes of terpenes; repression of ERG9 by replacement of the native promoter with a repressive methionine promoter in case of mono-, di- and sesquiterpenes; overexpression of BTS1 in case of di- and tetraterpenes. Site-directed mutagenesis such as Upc2p (G888A) in case of all classes of terpenes, ERG20p (K197G) in case of monoterpenes, HMG2p (K6R) in case of mono-, di- and sesquiterpenes could be some generic targets. Efforts are made to consolidate various studies

  17. Architecture and Biosynthesis of the Saccharomyces cerevisiae Cell Wall

    PubMed Central

    Orlean, Peter

    2012-01-01

    The wall gives a Saccharomyces cerevisiae cell its osmotic integrity; defines cell shape during budding growth, mating, sporulation, and pseudohypha formation; and presents adhesive glycoproteins to other yeast cells. The wall consists of β1,3- and β1,6-glucans, a small amount of chitin, and many different proteins that may bear N- and O-linked glycans and a glycolipid anchor. These components become cross-linked in various ways to form higher-order complexes. Wall composition and degree of cross-linking vary during growth and development and change in response to cell wall stress. This article reviews wall biogenesis in vegetative cells, covering the structure of wall components and how they are cross-linked; the biosynthesis of N- and O-linked glycans, glycosylphosphatidylinositol membrane anchors, β1,3- and β1,6-linked glucans, and chitin; the reactions that cross-link wall components; and the possible functions of enzymatic and nonenzymatic cell wall proteins. PMID:23135325

  18. Value-added biotransformation of cellulosic sugars by engineered Saccharomyces cerevisiae.

    PubMed

    Lane, Stephan; Dong, Jia; Jin, Yong-Su

    2018-07-01

    The substantial research efforts into lignocellulosic biofuels have generated an abundance of valuable knowledge and technologies for metabolic engineering. In particular, these investments have led to a vast growth in proficiency of engineering the yeast Saccharomyces cerevisiae for consuming lignocellulosic sugars, enabling the simultaneous assimilation of multiple carbon sources, and producing a large variety of value-added products by introduction of heterologous metabolic pathways. While microbial conversion of cellulosic sugars into large-volume low-value biofuels is not currently economically feasible, there may still be opportunities to produce other value-added chemicals as regulation of cellulosic sugar metabolism is quite different from glucose metabolism. This review summarizes these recent advances with an emphasis on employing engineered yeast for the bioconversion of lignocellulosic sugars into a variety of non-ethanol value-added products. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Xylose isomerase improves growth and ethanol production rates from biomass sugars for both Saccharomyces pastorianus and Saccharomyces cerevisiae.

    PubMed

    Miller, Kristen P; Gowtham, Yogender Kumar; Henson, J Michael; Harcum, Sarah W

    2012-01-01

    The demand for biofuel ethanol made from clean, renewable nonfood sources is growing. Cellulosic biomass, such as switch grass (Panicum virgatum L.), is an alternative feedstock for ethanol production; however, cellulosic feedstock hydrolysates contain high levels of xylose, which needs to be converted to ethanol to meet economic feasibility. In this study, the effects of xylose isomerase on cell growth and ethanol production from biomass sugars representative of switch grass were investigated using low cell density cultures. The lager yeast species Saccharomyces pastorianus was grown with immobilized xylose isomerase in the fermentation step to determine the impact of the glucose and xylose concentrations on the ethanol production rates. Ethanol production rates were improved due to xylose isomerase; however, the positive effect was not due solely to the conversion of xylose to xylulose. Xylose isomerase also has glucose isomerase activity, so to better understand the impact of the xylose isomerase on S. pastorianus, growth and ethanol production were examined in cultures provided fructose as the sole carbon. It was observed that growth and ethanol production rates were higher for the fructose cultures with xylose isomerase even in the absence of xylose. To determine whether the positive effects of xylose isomerase extended to other yeast species, a side-by-side comparison of S. pastorianus and Saccharomyces cerevisiae was conducted. These comparisons demonstrated that the xylose isomerase increased ethanol productivity for both the yeast species by increasing the glucose consumption rate. These results suggest that xylose isomerase can contribute to improved ethanol productivity, even without significant xylose conversion. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

  20. Tuning Chocolate Flavor through Development of Thermotolerant Saccharomyces cerevisiae Starter Cultures with Increased Acetate Ester Production

    PubMed Central

    Meersman, Esther; Steensels, Jan; Struyf, Nore; Paulus, Tinneke; Saels, Veerle; Mathawan, Melissa; Allegaert, Leen; Vrancken, Gino

    2015-01-01

    Microbial starter cultures have extensively been used to enhance the consistency and efficiency of industrial fermentations. Despite the advantages of such controlled fermentations, the fermentation involved in the production of chocolate is still a spontaneous process that relies on the natural microbiota at cocoa farms. However, recent studies indicate that certain thermotolerant Saccharomyces cerevisiae cultures can be used as starter cultures for cocoa pulp fermentation. In this study, we investigate the potential of specifically developed starter cultures to modulate chocolate aroma. Specifically, we developed several new S. cerevisiae hybrids that combine thermotolerance and efficient cocoa pulp fermentation with a high production of volatile flavor-active esters. In addition, we investigated the potential of two strains of two non-Saccharomyces species that produce very large amounts of fruity esters (Pichia kluyveri and Cyberlindnera fabianii) to modulate chocolate aroma. Gas chromatography-mass spectrometry (GC-MS) analysis of the cocoa liquor revealed an increased concentration of various flavor-active esters and a decrease in spoilage-related off-flavors in batches inoculated with S. cerevisiae starter cultures and, to a lesser extent, in batches inoculated with P. kluyveri and Cyb. fabianii. Additionally, GC-MS analysis of chocolate samples revealed that while most short-chain esters evaporated during conching, longer and more-fat-soluble ethyl and acetate esters, such as ethyl octanoate, phenylethyl acetate, ethyl phenylacetate, ethyl decanoate, and ethyl dodecanoate, remained almost unaffected. Sensory analysis by an expert panel confirmed significant differences in the aromas of chocolates produced with different starter cultures. Together, these results show that the selection of different yeast cultures opens novel avenues for modulating chocolate flavor. PMID:26590272