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  1. Mobilomics in Saccharomyces cerevisiae strains.

    Menconi, Giulia; Battaglia, Giovanni; Grossi, Roberto; Pisanti, Nadia; Marangoni, Roberto

    2013-03-20

    Mobile Genetic Elements (MGEs) are selfish DNA integrated in the genomes. Their detection is mainly based on consensus-like searches by scanning the investigated genome against the sequence of an already identified MGE. Mobilomics aims at discovering all the MGEs in a genome and understanding their dynamic behavior: The data for this kind of investigation can be provided by comparative genomics of closely related organisms. The amount of data thus involved requires a strong computational effort, which should be alleviated. Our approach proposes to exploit the high similarity among homologous chromosomes of different strains of the same species, following a progressive comparative genomics philosophy. We introduce a software tool based on our new fast algorithm, called regender, which is able to identify the conserved regions between chromosomes. Our case study is represented by a unique recently available dataset of 39 different strains of S.cerevisiae, which regender is able to compare in few minutes. By exploring the non-conserved regions, where MGEs are mainly retrotransposons called Tys, and marking the candidate Tys based on their length, we are able to locate a priori and automatically all the already known Tys and map all the putative Tys in all the strains. The remaining putative mobile elements (PMEs) emerging from this intra-specific comparison are sharp markers of inter-specific evolution: indeed, many events of non-conservation among different yeast strains correspond to PMEs. A clustering based on the presence/absence of the candidate Tys in the strains suggests an evolutionary interconnection that is very similar to classic phylogenetic trees based on SNPs analysis, even though it is computed without using phylogenetic information. The case study indicates that the proposed methodology brings two major advantages: (a) it does not require any template sequence for the wanted MGEs and (b) it can be applied to infer MGEs also for low coverage genomes

  2. Mobilomics in Saccharomyces cerevisiae strains

    2013-01-01

    Background Mobile Genetic Elements (MGEs) are selfish DNA integrated in the genomes. Their detection is mainly based on consensus–like searches by scanning the investigated genome against the sequence of an already identified MGE. Mobilomics aims at discovering all the MGEs in a genome and understanding their dynamic behavior: The data for this kind of investigation can be provided by comparative genomics of closely related organisms. The amount of data thus involved requires a strong computational effort, which should be alleviated. Results Our approach proposes to exploit the high similarity among homologous chromosomes of different strains of the same species, following a progressive comparative genomics philosophy. We introduce a software tool based on our new fast algorithm, called regender, which is able to identify the conserved regions between chromosomes. Our case study is represented by a unique recently available dataset of 39 different strains of S.cerevisiae, which regender is able to compare in few minutes. By exploring the non–conserved regions, where MGEs are mainly retrotransposons called Tys, and marking the candidate Tys based on their length, we are able to locate a priori and automatically all the already known Tys and map all the putative Tys in all the strains. The remaining putative mobile elements (PMEs) emerging from this intra–specific comparison are sharp markers of inter–specific evolution: indeed, many events of non–conservation among different yeast strains correspond to PMEs. A clustering based on the presence/absence of the candidate Tys in the strains suggests an evolutionary interconnection that is very similar to classic phylogenetic trees based on SNPs analysis, even though it is computed without using phylogenetic information. Conclusions The case study indicates that the proposed methodology brings two major advantages: (a) it does not require any template sequence for the wanted MGEs and (b) it can be applied to

  3. Possible roles of vacuolar H+-ATPase and mitochondrial function in tolerance to air-drying stress revealed by genome-wide screening of Saccharomyces cerevisiae deletion strains.

    Shima, Jun; Ando, Akira; Takagi, Hiroshi

    2008-03-01

    Yeasts used in bread making are exposed to air-drying stress during dried yeast production processes. To clarify the genes required for air-drying tolerance, we performed genome-wide screening using the complete deletion strain collection of diploid Saccharomyces cerevisiae. The screening identified 278 gene deletions responsible for air-drying sensitivity. These genes were classified based on their cellular function and on the localization of their gene products. The results showed that the genes required for air-drying tolerance were frequently involved in mitochondrial functions and in connection with vacuolar H(+)-ATPase, which plays a role in vacuolar acidification. To determine the role of vacuolar acidification in air-drying stress tolerance, we monitored intracellular pH. The results showed that intracellular acidification was induced during air-drying and that this acidification was amplified in a deletion mutant of the VMA2 gene encoding a component of vacuolar H(+)-ATPase, suggesting that vacuolar H(+)-ATPase helps maintain intracellular pH homeostasis, which is affected by air-drying stress. To determine the effects of air-drying stress on mitochondria, we analysed the mitochondrial membrane potential under air-drying stress conditions using MitoTracker. The results showed that mitochondria were extremely sensitive to air-drying stress, suggesting that a mitochondrial function is required for tolerance to air-drying stress. We also analysed the correlation between oxidative-stress sensitivity and air-drying-stress sensitivity. The results suggested that oxidative stress is a critical determinant of sensitivity to air-drying stress, although ROS-scavenging systems are not necessary for air-drying stress tolerance. (c) 2008 John Wiley & Sons, Ltd.

  4. Evaluation of cytochrome P-450 concentration in Saccharomyces cerevisiae strains

    Míriam Cristina Sakuragui Matuo

    2010-09-01

    Full Text Available Saccharomyces cerevisiae has been widely used in mutagenicity tests due to the presence of a cytochrome P-450 system, capable of metabolizing promutagens to active mutagens. There are a large number of S. cerevisiae strains with varying abilities to produce cytochrome P-450. However, strain selection and ideal cultivation conditions are not well defined. We compared cytochrome P-450 levels in four different S. cerevisiae strains and evaluated the cultivation conditions necessary to obtain the highest levels. The amount of cytochrome P-450 produced by each strain varied, as did the incubation time needed to reach the maximum level. The highest cytochrome P-450 concentrations were found in media containing fermentable sugars. The NCYC 240 strain produced the highest level of cytochrome P-450 when grown in the presence of 20 % (w/v glucose. The addition of ethanol to the media also increased cytochrome P-450 synthesis in this strain. These results indicate cultivation conditions must be specific and well-established for the strain selected in order to assure high cytochrome P-450 levels and reliable mutagenicity results.Linhagens de Saccharomyces cerevisiae tem sido amplamente empregadas em testes de mutagenicidade devido à presença de um sistema citocromo P-450 capaz de metabolizar substâncias pró-mutagênicas à sua forma ativa. Devido à grande variedade de linhagens de S. cerevisiae com diferentes capacidades de produção de citocromo P-450, torna-se necessária a seleção de cepas, bem como a definição das condições ideais de cultivo. Neste trabalho, foram comparados os níveis de citocromo P-450 em quatro diferentes linhagens de S. cerevisiae e avaliadas as condições de cultivo necessárias para obtenção de altas concentrações deste sistema enzimático. O maior nível enzimático foi encontrado na linhagem NCYC 240 em presença de 20 % de glicose (p/v. A adição de etanol ao meio de cultura também produziu um aumento na s

  5. Isolation, identification and characterization of regional indigenous Saccharomyces cerevisiae strains

    Hana Šuranská

    2016-03-01

    Full Text Available Abstract In the present work we isolated and identified various indigenous Saccharomyces cerevisiae strains and screened them for the selected oenological properties. These S. cerevisiae strains were isolated from berries and spontaneously fermented musts. The grape berries (Sauvignon blanc and Pinot noir were grown under the integrated and organic mode of farming in the South Moravia (Czech Republic wine region. Modern genotyping techniques such as PCR-fingerprinting and interdelta PCR typing were employed to differentiate among indigenous S. cerevisiae strains. This combination of the methods provides a rapid and relatively simple approach for identification of yeast of S. cerevisiae at strain level. In total, 120 isolates were identified and grouped by molecular approaches and 45 of the representative strains were tested for selected important oenological properties including ethanol, sulfur dioxide and osmotic stress tolerance, intensity of flocculation and desirable enzymatic activities. Their ability to produce and utilize acetic/malic acid was examined as well; in addition, H2S production as an undesirable property was screened. The oenological characteristics of indigenous isolates were compared to a commercially available S. cerevisiae BS6 strain, which is commonly used as the starter culture. Finally, some indigenous strains coming from organically treated grape berries were chosen for their promising oenological properties and these strains will be used as the starter culture, because application of a selected indigenous S. cerevisiae strain can enhance the regional character of the wines.

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

    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.

  7. Potential application of Saccharomyces cerevisiae strains for the ...

    This paper aimed at evaluating the fermentation behavior of selected Saccharomyces cerevisiae strains in banana pulp and they were compared with commercial yeast (baker's yeast) for subsequent production of distilled spirits. Five types of microorganisms were used: Four yeast strains obtained from accredited ...

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

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

    2005-01-01

    .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-1α 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......The probiotic potential of IS Saccharomyces cerevisiae strains used for production of foods or bevel-ages 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% Ox-all. Adhesion...

  9. The use of genetically modified Saccharomyces cerevisiae strains in the wine industry.

    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.

  10. Mead production: selection and characterization assays of Saccharomyces cerevisiae strains.

    Pereira, Ana Paula; Dias, Teresa; Andrade, João; Ramalhosa, Elsa; Estevinho, Letícia M

    2009-08-01

    Mead is a traditional drink, which results from the alcoholic fermentation of diluted honey carried out by yeasts. However, when it is produced in a homemade way, mead producers find several problems, namely, the lack of uniformity in the final product, delayed and arrested fermentations, and the production of "off-flavours" by the yeasts. These problems are usually associated with the inability of yeast strains to respond and adapt to unfavourable and stressful growth conditions. The main objectives of this work were to evaluate the capacity of Saccharomyces cerevisiae strains, isolated from honey of the Trás-os-Montes (Northeast Portugal), to produce mead. Five strains from honey, as well as one laboratory strain and one commercial wine strain, were evaluated in terms of their fermentation performance under ethanol, sulphur dioxide and osmotic stress. All the strains showed similar behaviour in these conditions. Two yeasts strains isolated from honey and the commercial wine strain were further tested for mead production, using two different honey (a dark and a light honey), enriched with two supplements (one commercial and one developed by the research team), as fermentation media. The results obtained in this work show that S. cerevisiae strains isolated from honey, are appropriate for mead production. However it is of extreme importance to take into account the characteristics of the honey, and supplements used in the fermentation medium formulation, in order to achieve the best results in mead production.

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

    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.

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

    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

  13. Redox balancing in recombinant strains of Saccharomyces cerevisiae

    Anderlund, M

    1998-09-01

    In metabolically engineered Saccharomyces cerevisiae expressing Pichia stipitis XYL1 and XYL2 genes, encoding xylose reductase (XR) and xylitol dehydrogenase (XDH), respectively, xylitol is excreted as the major product during anaerobic xylose fermentation and only low yields of ethanol are produced. This has been interpreted as a result of the dual cofactor dependence of XR and the exclusive use of NAD{sup +} by XDH. The excretion of xylitol was completely stopped and the formation of glycerol and acetic acid were reduced in xylose utilising S. cerevisiae strains cultivated in oxygen-limited conditions by expressing lower levels of XR than of XDH. The expression level of XYL1 and XYL2 were controlled by changing the promoters and transcription directions of the genes. A new functional metabolic pathway was established when Thermus thermophilus xylA gene was expressed in S. cerevisiae. The recombinant strain was able to ferment xylose to ethanol when cultivated on a minimal medium containing xylose as only carbon source. In order to create a channeled metabolic transfer in the two first steps of the xylose metabolism, XYL1 and XYL2 were fused in-frame and expressed in S. cerevisiae. When the fusion protein, containing a linker of three amino acids, was co expressed together with native XR and XDH monomers, enzyme complexes consisting of chimeric and native subunits were formed. The total activity of these complexes exhibited 10 and 9 times higher XR and XDH activity, respectively, than the original conjugates, consisting of only chimeric subunits. This strain produced less xylitol and the xylitol yield was lower than with strains only expressing native XR and XDH monomers. In addition, more ethanol and less acetic acid were formed. A new gene encoding the cytoplasmic transhydrogenase from Azotobacter vinelandii was cloned. The enzyme showed high similarity to the family of pyridine nucleotide-disulphide oxidoreductase. To analyse the physiological effect of

  14. Growth temperature exerts differential physiological and transcriptional responses in laboratory and wine strains of Saccharomyces cerevisiae

    Pizarra, Francisco J.; Jewett, Michael Christopher; Nielsen, Jens

    2008-01-01

    Laboratory strains of Saccharomyces cerevisiae have been widely used as a model for studying eukaryotic cells and mapping the molecular mechanisms of many different human diseases. Industrial wine yeasts, on the other hand, have been selected on the basis of their adaptation to stringent environm......Laboratory strains of Saccharomyces cerevisiae have been widely used as a model for studying eukaryotic cells and mapping the molecular mechanisms of many different human diseases. Industrial wine yeasts, on the other hand, have been selected on the basis of their adaptation to stringent...... environmental conditions and the organoleptic properties that they confer to wine. Here, we used a two-factor design to study the responses of a standard laboratory strain, CEN.PK113-7D, and an industrial wine yeast strain, EC1118, to growth temperatures of 15 degrees C and 30 degrees C in nitrogen......-limited, anaerobic, steady-state chemostat cultures. Physiological characterization revealed that the growth temperature strongly impacted the biomass yield of both strains. Moreover, we found that the wine yeast was better adapted to mobilizing resources for biomass production and that the laboratory yeast...

  15. Benchmarking two commonly used Saccharomyces cerevisiae strains for heterologous vanillin-β-glucoside production

    Tomas Strucko

    2015-12-01

    Full Text Available The yeast Saccharomyces cerevisiae is a widely used eukaryotic model organism and a key cell factory for production of biofuels and wide range of chemicals. From the broad palette of available yeast strains, the most popular are those derived from laboratory strain S288c and the industrially relevant CEN.PK strain series. Importantly, in recent years these two strains have been subjected to comparative “-omics” analyzes pointing out significant genotypic and phenotypic differences. It is therefore possible that the two strains differ significantly with respect to their potential as cell factories for production of specific compounds. To examine this possibility, we have reconstructed a de novo vanillin-β-glucoside pathway in an identical manner in S288c and CEN.PK strains. Characterization of the two resulting strains in two standard conditions revealed that the S288c background strain produced up to 10-fold higher amounts of vanillin-β-glucoside compared to CEN.PK. This study demonstrates that yeast strain background may play a major role in the outcome of newly developed cell factories for production of a given product. Keywords: Yeast, Cell factory, Strain choice, Heterologous production, Vanillin-glucoside, Shikimate pathway

  16. Evaluation of molecular typing techniques to assign genetic diversity among Saccharomyces cerevisiae strains

    Baleiras Couto, M.M.; Eijsma, B.; Hofstra, H.; Huis in 't Veld, J.H.J.; Vossen, J.M.B.M. van der

    1996-01-01

    Discrimination of strains within the species Saccharomyces cerevisiae was demonstrated by the use of four different techniques to type 15 strains isolated from spoiled wine and beer. Random amplified polymorphic DNA with specific oligonucleotides and PCR fingerprinting with the microsatellite

  17. Effects of Six Commercial Saccharomyces cerevisiae Strains on Phenolic Attributes, Antioxidant Activity, and Aroma of Kiwifruit (Actinidia deliciosa cv.) Wine

    Li, Xingchen; Cao, Lin; Li, Shaohua; Wang, Ranran; Jiang, Zijing; Che, Zhenming; Lin, Hongbin

    2017-01-01

    “Hayward” kiwifruit (Actinidia deliciosa cv.), widely planted all around the world, were fermented with six different commercial Saccharomyces cerevisiae strains (BM4×4, RA17, RC212, WLP77, JH-2, and CR476) to reveal their influence on the phenolic profiles, antioxidant activity, and aromatic components. Significant differences in the levels of caffeic acid, protocatechuate, and soluble solid content were found among wines with the six fermented strains. Wines fermented with RC212 strain exhibited the highest total phenolic acids as well as DPPH radical scavenging ability and also had the strongest ability to produce volatile esters. Wines made with S. cerevisiae BM 4×4 had the highest content of volatile acids, while the highest alcohol content was presented in CR476 wines. Scoring spots of wines with these strains were separated in different quadrants on the components of phenolics and aromas by principal component analyses. Kiwifruit wines made with S. cerevisiae RC212 were characterized by a rich fruity flavor, while CR476 strain and WLP77 strain produced floral flavors and green aromas, respectively. Altogether, the results indicated that the use of S. cerevisiae RC212 was the most suitable for the fermentation of kiwifruit wine with desirable characteristics. PMID:28251154

  18. Radiosensitivity of Saccharomyces cerevisiae W303-1A and BY4741 Strains

    Park, Ji Young; Kim, Jin Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Nili, Mohammad [Dawnesh Radiation Research Institute, Barcelona (Spain)

    2011-05-15

    Saccharomyces cerevisiae, a simple eukaryotic cell, has been widely used as a model for all eukaryotes including humans for the study of fundamental cellular processes such as DNA replication, DNA recombination, cell cycle, cell division and metabolism. Numerous laboratory strains are used in yeast research. Most of the mutants have been derived from the two widely used laboratory strains W303-1A and BY4741. While BY4741 is a derivative of S288C, used in the systematic sequencing of the S. cerevisiae genome, strains with a W303 background serve in many physiological and biochemical studies. It was found in a recent study that W303-1A contains a mutant allele of YBP1, ybp1-1, encoding four amino acid substitutions, that results in increased peroxide sensitivity. Mutation of ybp1-1 is not a complete loss of function allele as it is more resistant to peroxides than the knock-out mutant. Ybp1 is required for oxidation of specific cysteine residues of the transcription factor Yap1p resulting in the nuclear localization of Yap1p in response to stress. Ionizing radiation (IR) can produce highly reactive hydroxyl radicals through the decomposition of cellular water, such as superoxide anion radical, hydrogen peroxide, hydroxyl radical. These reactive oxygen species (ROS) can cause wide-ranging cellular damage, including DNA double-strand breaks (DSBs), lipid peroxidation, and protein modification. Also, ROS produced by IR cause oxidative stress. Detoxification enzymes are activated for ROS scavenging against oxidative stress. Also, antioxidants are used for detoxification of ROS and reduction of oxidative damage. NAC, one of the antioxidants, is a precursor for glutathione (GSH). The aim of the present study was to compare the differences in radiosensitivity associated cell viability between the two strains. Also, effect of NAC against IR on cell protection was investigated

  19. A novel strategy to construct yeast Saccharomyces cerevisiae strains for very high gravity fermentation.

    Xianglin Tao

    Full Text Available Very high gravity (VHG fermentation is aimed to considerably increase both the fermentation rate and the ethanol concentration, thereby reducing capital costs and the risk of bacterial contamination. This process results in critical issues, such as adverse stress factors (ie., osmotic pressure and ethanol inhibition and high concentrations of metabolic byproducts which are difficult to overcome by a single breeding method. In the present paper, a novel strategy that combines metabolic engineering and genome shuffling to circumvent these limitations and improve the bioethanol production performance of Saccharomyces cerevisiae strains under VHG conditions was developed. First, in strain Z5, which performed better than other widely used industrial strains, the gene GPD2 encoding glycerol 3-phosphate dehydrogenase was deleted, resulting in a mutant (Z5ΔGPD2 with a lower glycerol yield and poor ethanol productivity. Second, strain Z5ΔGPD2 was subjected to three rounds of genome shuffling to improve its VHG fermentation performance, and the best performing strain SZ3-1 was obtained. Results showed that strain SZ3-1 not only produced less glycerol, but also increased the ethanol yield by up to 8% compared with the parent strain Z5. Further analysis suggested that the improved ethanol yield in strain SZ3-1 was mainly contributed by the enhanced ethanol tolerance of the strain. The differences in ethanol tolerance between strains Z5 and SZ3-1 were closely associated with the cell membrane fatty acid compositions and intracellular trehalose concentrations. Finally, genome rearrangements in the optimized strain were confirmed by karyotype analysis. Hence, a combination of genome shuffling and metabolic engineering is an efficient approach for the rapid improvement of yeast strains for desirable industrial phenotypes.

  20. Robust metabolic responses to varied carbon sources in natural and laboratory strains of Saccharomyces cerevisiae.

    Wayne A Van Voorhies

    Full Text Available Understanding factors that regulate the metabolism and growth of an organism is of fundamental biologic interest. This study compared the influence of two different carbon substrates, dextrose and galactose, on the metabolic and growth rates of the yeast Saccharomyces cerevisiae. Yeast metabolic and growth rates varied widely depending on the metabolic substrate supplied. The metabolic and growth rates of a yeast strain maintained under long-term laboratory conditions was compared to strain isolated from natural condition when grown on different substrates. Previous studies had determined that there are numerous genetic differences between these two strains. However, the overall metabolic and growth rates of a wild isolate of yeast was very similar to that of a strain that had been maintained under laboratory conditions for many decades. This indicates that, at in least this case, metabolism and growth appear to be well buffered against genetic differences. Metabolic rate and cell number did not co-vary in a simple linear manner. When grown in either dextrose or galactose, both strains showed a growth pattern in which the number of cells continued to increase well after the metabolic rate began a sharp decline. Previous studied have reported that O₂ consumption in S. cerevisiae grown in reduced dextrose levels were elevated compared to higher levels. Low dextrose levels have been proposed to induce caloric restriction and increase life span in yeast. However, there was no evidence that reduced levels of dextrose increased metabolic rates, measured by either O₂ consumption or CO₂ production, in the strains used in this study.

  1. The Transcriptional Response of Diverse Saccharomyces cerevisiae Strains to Simulated Microgravity

    Neff, Lily S.; Fleury, Samantha T.; Galazka, Jonathan M.

    2018-01-01

    Spaceflight imposes multiple stresses on biological systems resulting in genome-scale adaptations. Understanding these adaptations and their underlying molecular mechanisms is important to clarifying and reducing the risks associated with spaceflight. One such risk is infection by microbes present in spacecraft and their associated systems and inhabitants. This risk is compounded by results suggesting that some microbes may exhibit increased virulence after exposure to spaceflight conditions. The yeast, S. cerevisiae, is a powerful microbial model system, and its response to spaceflight has been studied for decades. However, to date, these studies have utilized common lab strains. Yet studies on trait variation in S. cerevisiae demonstrate that these lab strains are not representative of wild yeast and instead respond to environmental stimuli in an atypical manner. Thus, it is not clear how transferable these results are to the wild S. cerevisiae strains likely to be encountered during spaceflight. To determine if diverse S. cerevisiae strains exhibit a conserved response to simulated microgravity, we will utilize a collection of 100 S. cerevisiae strains isolated from clinical, environmental and industrial settings. We will place selected S. cerevisiae strains in simulated microgravity using a high-aspect rotating vessel (HARV) and document their transcriptional response by RNA-sequencing and quantify similarities and differences between strains. Our research will have a strong impact on the understanding of how genetic diversity of microorganisms effects their response to spaceflight, and will serve as a platform for further studies.

  2. Stress Tolerance Variations in Saccharomyces cerevisiae Strains from Diverse Ecological Sources and Geographical Locations.

    Yan-Lin Zheng

    Full Text Available The budding yeast Saccharomyces cerevisiae is a platform organism for bioethanol production from various feedstocks and robust strains are desirable for efficient fermentation because yeast cells inevitably encounter stressors during the process. Recently, diverse S. cerevisiae lineages were identified, which provided novel resources for understanding stress tolerance variations and related shaping factors in the yeast. This study characterized the tolerance of diverse S. cerevisiae strains to the stressors of high ethanol concentrations, temperature shocks, and osmotic stress. The results showed that the isolates from human-associated environments overall presented a higher level of stress tolerance compared with those from forests spared anthropogenic influences. Statistical analyses indicated that the variations of stress tolerance were significantly correlated with both ecological sources and geographical locations of the strains. This study provides guidelines for selection of robust S. cerevisiae strains for bioethanol production from nature.

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

    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

  4. Novel strategy to improve vanillin tolerance and ethanol fermentation performances of Saccharomycere cerevisiae strains.

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

    2017-05-01

    The aim of this work was to develop a novel strategy for improving the vanillin tolerance and ethanol fermentation performances of Saccharomyces cerevisiae strains. Isogeneic diploid, triploid, and tetraploid S. cerevisiae strains were generated by genome duplication of haploid strain CEN.PK2-1C. Ploidy increments improved vanillin tolerance and diminished proliferation capability. Antimitotic drug methyl benzimidazol-2-ylcarbamate (MBC) was used to introduce chromosomal aberrations into the tetraploid S. cerevisiae strain. Interestingly, aneuploid mutants with DNA contents between triploid and tetraploid were more resistant to vanillin and showed faster ethanol fermentation rates than all euploid strains. The physiological characteristics of these mutants suggest that higher bioconversion capacities of vanillin and ergosterol contents might contribute to improved vanillin tolerance. This study demonstrates that genome duplication and MBC treatment is a powerful strategy to improve the vanillin tolerance of yeast strains. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Impact of different spray-drying conditions on the viability of wine Saccharomyces cerevisiae strains.

    Aponte, Maria; Troianiello, Gabriele Danilo; Di Capua, Marika; Romano, Raffaele; Blaiotta, Giuseppe

    2016-01-01

    Spray-drying (SD) is widely considered a suitable method to preserve microorganisms, but data regarding yeasts are still scanty. In this study, the effect of growing media, process variables and carriers over viability of a wild wine Saccharomyces (S.) cerevisiae LM52 was evaluated. For biomass production, the strain was grown (batch and fed-batch fermentation) in a synthetic, as well as in a beet sugar molasses based-medium. Drying of cells resuspended in several combinations of soluble starch and maltose was performed at different inlet and outlet temperatures. Under the best conditions-suspension in soluble starch plus maltose couplet to inlet and outlet temperatures of 110 and 55 °C, respectively-the loss of viability of S. cerevisiae LM52 was 0.8 ± 0.1 and 0.5 ± 0.2 Log c.f.u. g(-1) for synthetic and molasses-based medium, respectively. Similar results were obtained when S. cerevisiae strains Zymoflore F15 and EC1118, isolated from commercial active dry yeast (ADY), were tested. Moreover, powders retained a high vitality and showed good fermentation performances up to 6 month of storage, at both 4 and -20 °C. Finally, fermentation performances of different kinds of dried formulates (SD and ADY) compared with fresh cultures did not show significant differences. The procedure proposed allowed a small-scale production of yeast in continuous operation with relatively simple equipment, and may thus represent a rapid response-on-demand for the production of autochthonous yeasts for local wine-making.

  6. Excessive by-product formation : A key contributor to low isobutanol yields of engineered Saccharomyces cerevisiae strains

    Milne, N.S.W.; Wahl, S.A.; Van Maris, A.J.A.; Pronk, J.T.; Daran, J.M.

    2016-01-01

    It is theoretically possible to engineer Saccharomyces cerevisiae strains in which isobutanol is the predominant catabolic product and high-yielding isobutanol-producing strains are already reported by industry. Conversely, isobutanol yields of engineered S. cerevisiae strains reported in the

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

    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.

  8. Genome-wide identification of genes involved in growth and fermentation activity at low temperature in Saccharomyces cerevisiae.

    Salvadó, Zoel; Ramos-Alonso, Lucía; Tronchoni, Jordi; Penacho, Vanessa; García-Ríos, Estéfani; Morales, Pilar; Gonzalez, Ramon; Guillamón, José Manuel

    2016-11-07

    Fermentation at low temperatures is one of the most popular current winemaking practices because of its reported positive impact on the aromatic profile of wines. However, low temperature is an additional hurdle to develop Saccharomyces cerevisiae wine yeasts, which are already stressed by high osmotic pressure, low pH and poor availability of nitrogen sources in grape must. Understanding the mechanisms of adaptation of S. cerevisiae to fermentation at low temperature would help to design strategies for process management, and to select and improve wine yeast strains specifically adapted to this winemaking practice. The problem has been addressed by several approaches in recent years, including transcriptomic and other high-throughput strategies. In this work we used a genome-wide screening of S. cerevisiae diploid mutant strain collections to identify genes that potentially contribute to adaptation to low temperature fermentation conditions. Candidate genes, impaired for growth at low temperatures (12°C and 18°C), but not at a permissive temperature (28°C), were deleted in an industrial homozygous genetic background, wine yeast strain FX10, in both heterozygosis and homozygosis. Some candidate genes were required for growth at low temperatures only in the laboratory yeast genetic background, but not in FX10 (namely the genes involved in aromatic amino acid biosynthesis). Other genes related to ribosome biosynthesis (SNU66 and PAP2) were required for low-temperature fermentation of synthetic must (SM) in the industrial genetic background. This result coincides with our previous findings about translation efficiency with the fitness of different wine yeast strains at low temperature. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Improved xylose and arabinose utilization by an industrial recombinant Saccharomyces cerevisiae strain using evolutionary engineering

    Sanchez, R.G.; Karhumaa, Kaisa; Fonseca, C.

    2010-01-01

    Background: Cost-effective fermentation of lignocellulosic hydrolysate to ethanol by Saccharomyces cerevisiae requires efficient mixed sugar utilization. Notably, the rate and yield of xylose and arabinose co-fermentation to ethanol must be enhanced. Results: Evolutionary engineering was used...... to improve the simultaneous conversion of xylose and arabinose to ethanol in a recombinant industrial Saccharomyces cerevisiae strain carrying the heterologous genes for xylose and arabinose utilization pathways integrated in the genome. The evolved strain TMB3130 displayed an increased consumption rate...... of our knowledge, this is the first report that characterizes the molecular mechanisms for improved mixed-pentose utilization obtained by evolutionary engineering of a recombinant S. cerevisiae strain. Increased transport of pentoses and increased activities of xylose converting enzymes contributed...

  10. Genome-wide identification of Saccharomyces cerevisiae genes required for tolerance to acetic acid

    Sá-Correia Isabel

    2010-10-01

    Full Text Available Abstract Background Acetic acid is a byproduct of Saccharomyces cerevisiae alcoholic fermentation. Together with high concentrations of ethanol and other toxic metabolites, acetic acid may contribute to fermentation arrest and reduced ethanol productivity. This weak acid is also a present in lignocellulosic hydrolysates, a highly interesting non-feedstock substrate in industrial biotechnology. Therefore, the better understanding of the molecular mechanisms underlying S. cerevisiae tolerance to acetic acid is essential for the rational selection of optimal fermentation conditions and the engineering of more robust industrial strains to be used in processes in which yeast is explored as cell factory. Results The yeast genes conferring protection against acetic acid were identified in this study at a genome-wide scale, based on the screening of the EUROSCARF haploid mutant collection for susceptibility phenotypes to this weak acid (concentrations in the range 70-110 mM, at pH 4.5. Approximately 650 determinants of tolerance to acetic acid were identified. Clustering of these acetic acid-resistance genes based on their biological function indicated an enrichment of genes involved in transcription, internal pH homeostasis, carbohydrate metabolism, cell wall assembly, biogenesis of mitochondria, ribosome and vacuole, and in the sensing, signalling and uptake of various nutrients in particular iron, potassium, glucose and amino acids. A correlation between increased resistance to acetic acid and the level of potassium in the growth medium was found. The activation of the Snf1p signalling pathway, involved in yeast response to glucose starvation, is demonstrated to occur in response to acetic acid stress but no evidence was obtained supporting the acetic acid-induced inhibition of glucose uptake. Conclusions Approximately 490 of the 650 determinants of tolerance to acetic acid identified in this work are implicated, for the first time, in tolerance to

  11. Genome-wide transcription survey on flavour production in Saccharomyces cerevisiae

    Schoondermark-Stolk, Sung A.; Jansen, Michael; Verkleij, Arie J.; Verrips, C. Theo; Euverink, Gert-Jan W.; Dijkhuizen, Lubbert; Boonstra, Johannes

    2006-01-01

    The yeast Saccharomyces cerevisiae is widely used as aroma producer in the preparation of fermented foods and beverages. During food fermentations, secondary metabolites like 3-methyl-1-butanol, 4-methyl-2-oxopentanoate, 3-methyl-2-oxobutanoate and 3-methylbutyrate emerge. These four compounds have

  12. Genetic diversity and molecular characterization of Saccharomyces cerevisiae strains from winemaking environments

    Schuller, Dorit Elisabeth

    2004-01-01

    Tese de doutoramento em Ciências The principal aim of the present work is to assess the genetic diversity of fermenting Saccharomyces cerevisiae strains found in vineyards belonging to the Vinho Verde Region in order to create a strain collection representing the region’s biodiversity wealth as a basis for future strain selection and improvement programs. Validation of molecular techniques for accurate genotyping is an indispensable prerequisite for biogeographical surveys. Molecular ty...

  13. Sensitivity to Lovastatin of Saccharomyces cerevisiae Strains Deleted for Pleiotropic Drug Resistance (PDR) Genes

    Formenti, Luca Riccardo; Kielland-Brandt, Morten

    2011-01-01

    The use of statins is well established in human therapy, and model organisms such as Saccharomyces cerevisiae are commonly used in studies of drug action at molecular and cellular levels. The investigation of the resistance mechanisms towards statins may suggest new approaches to improve therapy...... based on the use of statins. We investigated the susceptibility to lovastatin of S. cerevisiae strains deleted for PDR genes, responsible for exporting hydrophobic and amphi-philic drugs, such as lovastatin. Strains deleted for the genes tested, PDR1, PDR3, PDR5 and SNQ2, exhibited remarkably different...

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

    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.

  15. A Novel Saccharomyces cerevisiae Killer Strain Secreting the X Factor Related to Killer Activity and Inhibition of S. cerevisiae K1, K2 and K28 Killer Toxins.

    Melvydas, Vytautas; Bružauskaitė, Ieva; Gedminienė, Genovaitė; Šiekštelė, Rimantas

    2016-09-01

    It was determined that Kx strains secrete an X factor which can inhibit all known Saccharomyces cerevisiae killer toxins (K1, K2, K28) and some toxins of other yeast species-the phenomenon not yet described in the scientific literature. It was shown that Kx type yeast strains posess a killer phenotype producing small but clear lysis zones not only on the sensitive strain α'1 but also on the lawn of S. cerevisiae K1, K2 and K28 type killer strains at temperatures between 20 and 30 °C. The pH at which killer/antikiller effect of Kx strain reaches its maximum is about 5.0-5.2. The Kx yeast were identified as to belong to S. cerevisiae species. Another newly identified S. cerevisiae killer strain N1 has killer activity but shows no antikilller properties against standard K1, K2 and K28 killer toxins. The genetic basis for Kx killer/antikiller phenotype was associated with the presence of M-dsRNA which is bigger than M-dsRNA of standard S. cerevisiae K1, K2, K28 type killer strains. Killer and antikiller features should be encoded by dsRNA. The phenomenon of antikiller (inhibition) properties was observed against some killer toxins of other yeast species. The molecular weight of newly identified killer toxins which produces Kx type strains might be about 45 kDa.

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

    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.

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

    Vanda Renata Reis

    Full Text Available Abstract 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.

  18. Ecological interactions among Saccharomyces cerevisiae strains: insight into the dominance phenomenon.

    Pérez-Torrado, Roberto; Rantsiou, Kalliopi; Perrone, Benedeta; Navarro-Tapia, Elisabeth; Querol, Amparo; Cocolin, Luca

    2017-03-07

    This study investigates the behaviour of Saccharomyces cerevisiae strains, in order to obtain insight into the intraspecies competition taking place in mixed populations of this species. Two strains of S. cerevisiae, one dominant and one non-dominant, were labelled and mixed, and individual fermentations were set up to study the transcriptomes of the strains by means of RNA-seq. The results obtained suggest that cell-to-cell contact and aggregation, which are driven by the expression of genes that are associated with the cell surface, are indispensable conditions for the achievement of dominance. Observations on mixed aggregates, made up of cells of both strains, which were detected by means of flow cytometry, have confirmed the transcriptomic data. Furthermore, overexpression of the SSU1 gene, which encodes for a transporter that confers resistance to sulphites, provides an ecological advantage to the dominant strain. A mechanistic model is proposed that sheds light on the dominance phenomenon between different strains of the S. cerevisiae species. The collected data suggest that cell-to-cell contact, together with differential sulphite production and resistance is important in determining the dominance of one strain over another.

  19. Saccharomyces cerevisiae strains tor second-generation ethanol production : from academie exploration to industrial implementation

    Jansen, Mickel L.A.; Bracher, J.M.; Papapetridis, I.; Verhoeven, M.D.; de Bruijn, J.A.; de Waal, P.; van Maris, A.J.A.; Klaassen, P; Pronk, J.T.

    2017-01-01

    The recent start-up of several full-scale ‘second generation’ ethanol plants marks a major milestone in the development of Saccharomyces cerevisiae strains for fermentation of lignocellulosic hydrolysates of agricultural residues and energy crops. After a discussion of the challenges that these

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

    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.

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

    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.

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

    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.

  3. Flux control-based design of furfural-resistance strains of Saccharomyces cerevisiae for lignocellulosic biorefinery.

    Unrean, Pornkamol

    2017-04-01

    We have previously developed a dynamic flux balance analysis of Saccharomyces cerevisiae for elucidation of genome-wide flux response to furfural perturbation (Unrean and Franzen, Biotechnol J 10(8):1248-1258, 2015). Herein, the dynamic flux distributions were analyzed by flux control analysis to identify target overexpressed genes for improved yeast robustness against furfural. The flux control coefficient (FCC) identified overexpressing isocitrate dehydrogenase (IDH1), a rate-controlling flux for ethanol fermentation, and dicarboxylate carrier (DIC1), a limiting flux for cell growth, as keys of furfural-resistance phenotype. Consistent with the model prediction, strain characterization showed 1.2- and 2.0-fold improvement in ethanol synthesis and furfural detoxification rates, respectively, by IDH1 overexpressed mutant compared to the control. DIC1 overexpressed mutant grew at 1.3-fold faster and reduced furfural at 1.4-fold faster than the control under the furfural challenge. This study hence demonstrated the FCC-based approach as an effective tool for guiding the design of robust yeast strains.

  4. Metabolic engineering of Saccharomyces cerevisiae ethanol strains PE-2 and CAT-1 for efficient lignocellulosic fermentation.

    Romaní, Aloia; Pereira, Filipa; Johansson, Björn; Domingues, Lucília

    2015-03-01

    In this work, Saccharomyces cerevisiae strains PE-2 and CAT-1, commonly used in the Brazilian fuel ethanol industry, were engineered for xylose fermentation, where the first fermented xylose faster than the latter, but also produced considerable amounts of xylitol. An engineered PE-2 strain (MEC1121) efficiently consumed xylose in presence of inhibitors both in synthetic and corn-cob hydrolysates. Interestingly, the S. cerevisiae MEC1121 consumed xylose and glucose simultaneously, while a CEN.PK based strain consumed glucose and xylose sequentially. Deletion of the aldose reductase GRE3 lowered xylitol production to undetectable levels and increased xylose consumption rate which led to higher final ethanol concentrations. Fermentation of corn-cob hydrolysate using this strain, MEC1133, resulted in an ethanol yield of 0.47 g/g of total sugars which is 92% of the theoretical yield. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. A set of haploid strains available for genetic studies of Saccharomyces cerevisiae flor yeasts.

    Coi, Anna Lisa; Legras, Jean-Luc; Zara, Giacomo; Dequin, Sylvie; Budroni, Marilena

    2016-09-01

    Flor yeasts of Saccharomyces cerevisiae have been extensively studied for biofilm formation, however the lack of specific haploid model strains has limited the application of genetic approaches such as gene knockout, allelic replacement and Quantitative Trait Locus mapping for the deciphering of the molecular basis of velum formation under biological ageing. The aim of this work was to construct a set of flor isogenic haploid strains easy to manipulate genetically. The analysis of the allelic variations at 12 minisatellite loci of 174 Saccharomyces cerevisiae strains allowed identifying three flor parental strains with different phylogenic positions. These strains were characterized for sporulation efficiency, growth on galactose, adherence to polystyrene, agar invasion, growth on wine and ability to develop a biofilm. Interestingly, the inability to grow on galactose was found associated with a frameshift in GAL4 gene that seems peculiar of flor strains. From these wild flor strains, isogenic haploid strains were constructed by deleting HO gene with a loxP-KanMX-loxP cassette followed by the removal of the kanamycin cassette. Haploid strains obtained were characterized for their phenotypic and genetic properties and compared with the parental strains. Preliminary results showed that the haploid strains represent new tools for genetic studies and breeding programs on biofilm formation. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Physiological studies in aerobic batch cultivations of Saccharomyces cerevisiae strains harboring the MEL1 gene

    Østergaard, Simon; Roca, Christophe Francois Aime; Ronnow, B.

    2000-01-01

    Physiological studies of Saccharomyces cerevisiae strains harboring the MEL1 gene were carried out in aerobic batch cultivations on glucose-galactose mixtures and on the disaccharide melibiose, which is hydrolyzed by the enzyme melibiase (Mel1, EC 3.2.1.22) into a glucose and a galactose moiety...... rates were 2.5-3.3-fold higher on glucose than on galactose for all the strains examined, and hence, ethanol production was pronounced on glucose due to respiro-fermentative metabolism. The T256 strain and the T200 strain having the MEL1 gene inserted in the HXK2 locus and the LEU2 locus, respectively...

  7. Geographical markers for Saccharomyces cerevisiae strains with similar technological origins domesticated for rice-based ethnic fermented beverages production in North East India.

    Jeyaram, Kumaraswamy; Tamang, Jyoti Prakash; Capece, Angela; Romano, Patrizia

    2011-11-01

    Autochthonous strains of Saccharomyces cerevisiae from traditional starters used for the production of rice-based ethnic fermented beverage in North East India were examined for their genetic polymorphism using mitochondrial DNA-RFLP and electrophoretic karyotyping. Mitochondrial DNA-RFLP analysis of S. cerevisiae strains with similar technological origins from hamei starter of Manipur and marcha starter of Sikkim revealed widely separated clusters based on their geographical origin. Electrophoretic karyotyping showed high polymorphism amongst the hamei strains within similar mitochondrial DNA-RFLP cluster and one unique karyotype of marcha strain was widely distributed in the Sikkim-Himalayan region. We conceptualized the possibility of separate domestication events for hamei strains in Manipur (located in the Indo-Burma biodiversity hotspot) and marcha strains in Sikkim (located in Himalayan biodiversity hotspot), as a consequence of less homogeneity in the genomic structure between these two groups, their clear separation being based on geographical origin, but not on technological origin and low strain level diversity within each group. The molecular markers developed based on HinfI-mtDNA-RFLP profile and the chromosomal doublets in chromosome VIII position of Sikkim-Himalayan strains could be effectively used as geographical markers for authenticating the above starter strains and differentiating them from other commercial strains.

  8. Bioaccumulation of uranium from waste water using different strains of Saccharomyces cerevisiae

    Tykva, R.; Novak, J.; Podracka, E.; Popa, K.

    2009-01-01

    Five different strains of Saccharomyces cerevisiae were tested for their abilities to accumulate uranium from waste water containing competitive ions. Samples of water passing out from a previous uranium mill were used. The strains tested possess different abilities to accumulate uranium. The kinetics of bioaccumulation, the leaching degree, the influence of cell density and their origin were investigated. Under the applied experimental conditions, more than a half of the total activity (uranium and the decay products) could be accumulated after 60 min contact time of 1 mL (S. cerevisiae) suspension and 5 mL of water. The other cations present in solution effectively competed for the uranium accumulation. 226 Ra and its decay products were completely retained using all tested strains. (authors)

  9. Influence of genetic background of engineered xylose-fermenting industrial Saccharomyces cerevisiae strains for ethanol production from lignocellulosic hydrolysates

    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...

  10. Relationship of trehalose accumulation with ethanol fermentation in industrial Saccharomyces cerevisiae yeast strains.

    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.

  11. Genome-wide screening of Saccharomyces cerevisiae genes regulated by vanillin.

    Park, Eun-Hee; Kim, Myoung-Dong

    2015-01-01

    During pretreatment of lignocellulosic biomass, a variety of fermentation inhibitors, including acetic acid and vanillin, are released. Using DNA microarray analysis, this study explored genes of the budding yeast Saccharomyces cerevisiae that respond to vanillin-induced stress. The expression of 273 genes was upregulated and that of 205 genes was downregulated under vanillin stress. Significantly induced genes included MCH2, SNG1, GPH1, and TMA10, whereas NOP2, UTP18, FUR1, and SPR1 were down regulated. Sequence analysis of the 5'-flanking region of upregulated genes suggested that vanillin might regulate gene expression in a stress response element (STRE)-dependent manner, in addition to a pathway that involved the transcription factor Yap1p. Retardation in the cell growth of mutant strains indicated that MCH2, SNG1, and GPH1 are intimately involved in vanillin stress response. Deletion of the genes whose expression levels were decreased under vanillin stress did not result in a notable change in S. cerevisiae growth under vanillin stress. This study will provide the basis for a better understanding of the stress response of the yeast S. cerevisiae to fermentation inhibitors.

  12. Ethanol production from xylose in engineered Saccharomyces cerevisiae strains. Current state and perspectives

    Matsushika, Akinori; Inoue, Hiroyuki; Sawayama, Shigeki [National Inst. of Advanced Industrial Science and Technology (AIST), Hiroshima (JP). Biomass Technology Research Center (BTRC); Kodaki, Tsutomu [Kyoto Univ. (Japan). Inst. of Advanced Energy

    2009-08-15

    Bioethanol production from xylose is important for utilization of lignocellulosic biomass as raw materials. The research on yeast conversion of xylose to ethanol has been intensively studied especially for genetically engineered Saccharomyces cerevisiae during the last 20 years. S. cerevisiae, which is a very safe microorganism that plays a traditional and major role in industrial bioethanol production, has several advantages due to its high ethanol productivity, as well as its high ethanol and inhibitor tolerance. However, this yeast cannot ferment xylose, which is the dominant pentose sugar in hydrolysates of lignocellulosic biomass. A number of different strategies have been applied to engineer yeasts capable of efficiently producing ethanol from xylose, including the introduction of initial xylose metabolism and xylose transport, changing the intracellular redox balance, and overexpression of xylulokinase and pentose phosphate pathways. In this review, recent progress with regard to these studies is discussed, focusing particularly on xylose-fermenting strains of S. cerevisiae. Recent studies using several promising approaches such as host strain selection and adaptation to obtain further improved xylose-utilizing S. cerevisiae are also addressed. (orig.)

  13. Production of volatile and sulfur compounds by ten Saccharomyces cerevisiae strains inoculated in Trebbiano must

    Francesca ePatrignani

    2016-03-01

    Full Text Available In wines, the presence of sulphur compounds is the resulting of several contributions among which yeast metabolism. The characterization of the starter Saccharomyces cerevisiae needs to be performed also taking into account this ability even if evaluated together with the overall metabolic profile. In this perspective, principal aim of this experimental research was the evaluation of the volatile profiles, throughout GC/MS technique coupled with solid phase micro extraction, of wines obtained throughout the fermentation of 10 strains of Saccharomyces cerevisiae. In addition, the production of sulphur compounds was further evaluated by using a gas-chromatograph coupled with a Flame Photometric Detector. Specifically, the ten strains were inoculated in Trebbiano musts and the fermentations were monitored for 19 days. In the produced wines, volatile and sulphur compounds as well as amino acid concentrations were investigated. Also the physico-chemical characteristics of the wines and their electronic nose profiles were evaluated.

  14. Genomics and Biochemistry of Saccharomyces cerevisiae Wine Yeast Strains.

    Eldarov, M A; Kishkovskaia, S A; Tanaschuk, T N; Mardanov, A V

    2016-12-01

    Saccharomyces yeasts have been used for millennia for the production of beer, wine, bread, and other fermented products. Long-term "unconscious" selection and domestication led to the selection of hundreds of strains with desired production traits having significant phenotypic and genetic differences from their wild ancestors. This review summarizes the results of recent research in deciphering the genomes of wine Saccharomyces strains, the use of comparative genomics methods to study the mechanisms of yeast genome evolution under conditions of artificial selection, and the use of genomic and postgenomic approaches to identify the molecular nature of the important characteristics of commercial wine strains of Saccharomyces. Succinctly, data concerning metagenomics of microbial communities of grapes and wine and the dynamics of yeast and bacterial flora in the course of winemaking is provided. A separate section is devoted to an overview of the physiological, genetic, and biochemical features of sherry yeast strains used to produce biologically aged wines. The goal of the review is to convince the reader of the efficacy of new genomic and postgenomic technologies as tools for developing strategies for targeted selection and creation of new strains using "classical" and modern techniques for improving winemaking technology.

  15. The Impact of Single Amino Acids on Growth and Volatile Aroma Production by Saccharomyces cerevisiae Strains

    Samantha Fairbairn; Alexander McKinnon; Hannibal T. Musarurwa; António C. Ferreira; António C. Ferreira; Florian F. Bauer

    2017-01-01

    Nitrogen availability and utilization by Saccharomyces cerevisiae significantly influence fermentation kinetics and the production of volatile compounds important for wine aroma. Amino acids are the most important nitrogen source and have been classified based on how well they support growth. This study evaluated the effect of single amino acids on growth kinetics and major volatile production of two phenotypically different commercial wine yeast strains in synthetic grape must. Four growth p...

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

    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. Screening Saccharomyces cerevisiae Distillery Strains in Industrial Media

    Twenty-four distillery yeast strains were obtained from the ARS Culture Collection (NRRL) in Peoria, IL, and screened for ethanol production at 30 and 35°C using industrial media. The medium used in the tests consisted of corn mash prepared by combining coarse ground corn, water, and stillage from a...

  18. Physiology of Saccharomyces cerevisiae strains isolated from Brazilian biomes: new insights into biodiversity and industrial applications

    Beato, Felipe B.; Bergdahl, Basti; Rosa, Carlos A.

    2016-01-01

    Fourteen indigenous Saccharomyces cerevisiae strains isolated from the barks of three tree species located in the Atlantic Rain Forest and Cerrado biomes in Brazil were genetically and physiologically compared to laboratory strains and to strains from the Brazilian fuel ethanol industry. Although...

  19. Induction of ploidy level increments in an asporogenous industrial strain of the yeast Saccaromyces cerevisiae by UV irradiation

    Sasaki, Takashi

    1992-01-01

    Cells of an asporogenous industrial strain of the yeast Saccaromyces cerevisiae were irradiated with UV light by using a method that was developed previously. This treatment gave rise to large-cell clones among the surviving cells, from which colonies consisting of cells with a normal morphology and a prototropic property were obtained. The large-cell trait of these was stably inheritable, with the cell volumes being about twice that of the parent for 7 years on a slant agar medium at 4C with repeated transfers. The cellular DNA content of these clones, in comparison to those of two authentic haploid strains, was determined by chemical analysis. The ratio of the DNA contents showed that the parent and its large-cell derivatives were a diploid and tetraploids, respectively. No abnormality was found in the chromosomal DNA patterns of the large-cell clones, at least as determined by agarose gel electrophoresis with a CHEF-DR II pulsed-field electrophoresis system. These findings led to the conclusion that the UV light method is applicable for inducing ploidy level increments in the widely used yeast species S. cerevisiae

  20. The Influence of Some Commercial Saccharomyces cerevisiae Strains on the Quality of Chardonnay Wines

    Vesna Podgorski

    2003-01-01

    Full Text Available Changes in some aroma compounds and sensory properties caused by different commercial S. cerevisiae strains and by epiphyte microorganisms in Chardonnay wines were investigated. Wines fermented with the Lalvin-71 B strain contained significantly lower concentrations of alcohol, isoamyl alcohol, isobutanol and total acidity than the wines obtained from spontaneous and other inoculated fermentations. The highest concentrations of 2-phenyl ethanol and 2-phenyl ethyl acetate were found in the spontaneously fermented wines, whereas no essential changes in these compounds were found among the wines of other treatments. Compared to the spontaneous fermentation, Lalvin-71 B strain fermented wines had somewhat higher concentrations of butyric and caproic acid and ethyl butyrate. Lalvin-71 B strain fermented wines were assessed as the best whereas the quality of the wines produced with Lalvin aromatic-2056 strain was the most inferior in quality.

  1. Xylitol production by genetically modified industrial strain of Saccharomyces cerevisiae using glycerol as co-substrate.

    Kogje, Anushree B; Ghosalkar, Anand

    2017-06-01

    Xylitol is commercially used in chewing gum and dental care products as a low calorie sweetener having medicinal properties. Industrial yeast strain of S. cerevisiae was genetically modified to overexpress an endogenous aldose reductase gene GRE3 and a xylose transporter gene SUT1 for the production of xylitol. The recombinant strain (XP-RTK) carried the expression cassettes of both the genes and the G418 resistance marker cassette KanMX integrated into the genome of S. cerevisiae. Short segments from the 5' and 3' delta regions of the Ty1 retrotransposons were used as homology regions for integration of the cassettes. Xylitol production by the industrial recombinant strain was evaluated using hemicellulosic hydrolysate of the corn cob with glucose as the cosubstrate. The recombinant strain XP-RTK showed significantly higher xylitol productivity (212 mg L -1  h -1 ) over the control strain XP (81 mg L -1  h -1 ). Glucose was successfully replaced by glycerol as a co-substrate for xylitol production by S. cerevisiae. Strain XP-RTK showed the highest xylitol productivity of 318.6 mg L -1  h -1 and titre of 47 g L -1 of xylitol at 12 g L -1 initial DCW using glycerol as cosubstrate. The amount of glycerol consumed per amount of xylitol produced (0.47 mol mol -1 ) was significantly lower than glucose (23.7 mol mol -1 ). Fermentation strategies such as cell recycle and use of the industrial nitrogen sources were demonstrated using hemicellulosic hydrolysate for xylitol production.

  2. Genome-Wide Screen for Saccharomyces cerevisiae Genes Contributing to Opportunistic Pathogenicity in an Invertebrate Model Host

    Sujal S. Phadke

    2018-01-01

    Full Text Available Environmental opportunistic pathogens can exploit vulnerable hosts through expression of traits selected for in their natural environments. Pathogenicity is itself a complicated trait underpinned by multiple complex traits, such as thermotolerance, morphology, and stress response. The baker’s yeast, Saccharomyces cerevisiae, is a species with broad environmental tolerance that has been increasingly reported as an opportunistic pathogen of humans. Here we leveraged the genetic resources available in yeast and a model insect species, the greater waxmoth Galleria mellonella, to provide a genome-wide analysis of pathogenicity factors. Using serial passaging experiments of genetically marked wild-type strains, a hybrid strain was identified as the most fit genotype across all replicates. To dissect the genetic basis for pathogenicity in the hybrid isolate, bulk segregant analysis was performed which revealed eight quantitative trait loci significantly differing between the two bulks with alleles from both parents contributing to pathogenicity. A second passaging experiment with a library of deletion mutants for most yeast genes identified a large number of mutations whose relative fitness differed in vivo vs. in vitro, including mutations in genes controlling cell wall integrity, mitochondrial function, and tyrosine metabolism. Yeast is presumably subjected to a massive assault by the innate insect immune system that leads to melanization of the host and to a large bottleneck in yeast population size. Our data support that resistance to the innate immune response of the insect is key to survival in the host and identifies shared genetic mechanisms between S. cerevisiae and other opportunistic fungal pathogens.

  3. Feasibility of protein turnover studies in prototroph Saccharomyces cerevisiae strains.

    Martin-Perez, Miguel; Villén, Judit

    2015-04-07

    Quantitative proteomics studies of yeast that use metabolic labeling with amino acids rely on auxotrophic mutations of one or more genes on the amino acid biosynthesis pathways. These mutations affect yeast metabolism and preclude the study of some biological processes. Overcoming this limitation, it has recently been described that proteins in a yeast prototrophic strain can also be metabolically labeled with heavy amino acids. However, the temporal profiles of label incorporation under the different phases of the prototroph's growth have not been examined. Labeling trajectories are important in the study of protein turnover and dynamics, in which label incorporation into proteins is monitored across many time points. Here we monitored protein labeling trajectories for 48 h after a pulse with heavy lysine in a yeast prototrophic strain and compared them with those of a lysine auxotrophic yeast. Labeling was successful in prototroph yeast during exponential growth phase but not in stationary phase. Furthermore, we were able to determine the half-lives of more than 1700 proteins during exponential phase of growth with high accuracy and reproducibility. We found a median half-life of 2 h in both strains, which corresponds with the cellular doubling time. Nucleolar and ribosomal proteins showed short half-lives, whereas mitochondrial proteins and other energy production enzymes presented longer half-lives. Except for some proteins involved in lysine biosynthesis, we observed a high correlation in protein half-lives between prototroph and auxotroph strains. Overall, our results demonstrate the feasibility of using prototrophs for proteomic turnover studies and provide a reliable data set of protein half-lives in exponentially growing yeast.

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

    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.

  5. Genetic analysis of Saccharomyces cerevisiae strains isolated from palm wine in eastern Nigeria. Comparison with other African strains.

    Ezeronye, O U; Legras, J-L

    2009-05-01

    To study the yeast diversity of Nigerian palm wines by comparison with other African strains. Twenty-three Saccharomyces cerevisiae strains were obtained from palm wine samples collected at four locations in eastern Nigeria, and characterized using different molecular techniques: internal transcribed spacer restriction fragment length polymorphism and sequence analysis, pulsed field gel electrophoresis, inter delta typing and microsatellite multilocus analysis. These techniques revealed that palm wine yeasts represent a group of closely related strains that includes other West African isolates (CBS400, NCYC110, DVPG6044). Population analysis revealed an excess of homozygote strains and an allelic richness similar to wine suggestive of local domestication. Several other African yeast strains were not connected to this group. Ghana sorghum beer strains and other African strains (DBVPG1853 and MUCL28071) displayed strikingly high relatedness with European bread, beer or wine strains, and the genome of strain MUCL30909 contained African and wine-type alleles, indicating its hybrid origin. Nigerian palm wine yeast represents a local specific yeast flora, whereas a European origin or hybrid was suspected for several other Africa isolates. This study presents the first genetic characterization of an autochthonous African palm wine yeast population and confirms the idea that human intervention has favoured yeast migration.

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

    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.

  7. Fermentation performance of engineered and evolved xylose-fermenting Saccharomyces cerevisiae strains

    Sonderegger, M.; Jeppsson, M.; Larsson, C.

    2004-01-01

    Lignocellulose hydrolysate is an abundant substrate for bioethanol production. The ideal microorganism for such a fermentation process should combine rapid and efficient conversion of the available carbon sources to ethanol with high tolerance to ethanol and to inhibitory components in the hydrol......Lignocellulose hydrolysate is an abundant substrate for bioethanol production. The ideal microorganism for such a fermentation process should combine rapid and efficient conversion of the available carbon sources to ethanol with high tolerance to ethanol and to inhibitory components...... in the hydrolysate. A particular biological problem are the pentoses, which are not naturally metabolized by the main industrial ethanol producer Saccharomyces cerevisiae. Several recombinant, mutated, and evolved xylose fermenting S. cerevisiae strains have been developed recently. We compare here the fermentation...

  8. 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.

    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.

  9. Responses of Saccharomyces cerevisiae Strains from Different Origins to Elevated Iron Concentrations

    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

  10. Proteome-wide analysis of lysine acetylation suggests its broad regulatory scope in Saccharomyces cerevisiae

    Henriksen, Peter; Wagner, Sebastian Alexander; Weinert, Brian Tate

    2012-01-01

    Post-translational modification of proteins by lysine acetylation plays important regulatory roles in living cells. The budding yeast Saccharomyces cerevisiae is a widely used unicellular eukaryotic model organism in biomedical research. S. cerevisiae contains several evolutionary conserved lysine...... acetyltransferases and deacetylases. However, only a few dozen acetylation sites in S. cerevisiae are known, presenting a major obstacle for further understanding the regulatory roles of acetylation in this organism. Here we use high resolution mass spectrometry to identify about 4000 lysine acetylation sites in S....... cerevisiae. Acetylated proteins are implicated in the regulation of diverse cytoplasmic and nuclear processes including chromatin organization, mitochondrial metabolism, and protein synthesis. Bioinformatic analysis of yeast acetylation sites shows that acetylated lysines are significantly more conserved...

  11. Extracellular Phytase Production by the Wine Yeast S. cerevisiae (Finarome Strain) during Submerged Fermentation.

    Kłosowski, Grzegorz; Mikulski, Dawid; Jankowiak, Oliwia

    2018-04-08

    One of the key steps in the production of phytases of microbial origin is selection of culture parameters, followed by isolation of the enzyme and evaluation of its catalytic activity. It was found that conditions for S. cerevisiae yeast culture, strain Finarome, giving the reduction in phytic acid concentration of more than 98% within 24 h of incubation were as follows: pH 5.5, 32 °C, continuous stirring at 80 rpm, the use of mannose as a carbon source and aspartic acid as a source of nitrogen. The highest catalytic activity of the isolated phytase was observed at 37 °C, pH 4.0 and using phytate as substrate at concentration of 5.0 mM. The presence of ethanol in the medium at a concentration of 12% v / v reduces the catalytic activity to above 60%. Properties of phytase derived from S. cerevisiae yeast culture, strain Finarome, indicate the possibility of its application in the form of a cell's free crude protein isolate for the hydrolysis of phytic acid to improve the efficiency of alcoholic fermentation processes. Our results also suggest a possibility to use the strain under study to obtain a fusant derived with specialized distillery strains, capable of carrying out a highly efficient fermentation process combined with the utilization of phytates.

  12. Saccharomyces cerevisiae strains for second-generation ethanol production: from academic exploration to industrial implementation

    Jansen, Mickel L. A.; Bracher, Jasmine M.; Papapetridis, Ioannis; Verhoeven, Maarten D.; de Bruijn, Hans; de Waal, Paul P.; van Maris, Antonius J. A.; Klaassen, Paul

    2017-01-01

    Abstract The recent start-up of several full-scale ‘second generation’ ethanol plants marks a major milestone in the development of Saccharomyces cerevisiae strains for fermentation of lignocellulosic hydrolysates of agricultural residues and energy crops. After a discussion of the challenges that these novel industrial contexts impose on yeast strains, this minireview describes key metabolic engineering strategies that have been developed to address these challenges. Additionally, it outlines how proof-of-concept studies, often developed in academic settings, can be used for the development of robust strain platforms that meet the requirements for industrial application. Fermentation performance of current engineered industrial S. cerevisiae strains is no longer a bottleneck in efforts to achieve the projected outputs of the first large-scale second-generation ethanol plants. Academic and industrial yeast research will continue to strengthen the economic value position of second-generation ethanol production by further improving fermentation kinetics, product yield and cellular robustness under process conditions. PMID:28899031

  13. Thermotolerant Kluyveromyces marxianus and Saccharomyces cerevisiae strains representing potentials for bioethanol production from Jerusalem artichoke by consolidated bioprocessing.

    Hu, Nan; Yuan, Bo; Sun, Juan; Wang, Shi-An; Li, Fu-Li

    2012-09-01

    Thermotolerant inulin-utilizing yeast strains are desirable for ethanol production from Jerusalem artichoke tubers by consolidated bioprocessing (CBP). To obtain such strains, 21 naturally occurring yeast strains isolated by using an enrichment method and 65 previously isolated Saccharomyces cerevisiae strains were investigated in inulin utilization, extracellular inulinase activity, and ethanol fermentation from inulin and Jerusalem artichoke tuber flour at 40 °C. The strains Kluyveromyces marxianus PT-1 (CGMCC AS2.4515) and S. cerevisiae JZ1C (CGMCC AS2.3878) presented the highest extracellular inulinase activity and ethanol yield in this study. The highest ethanol concentration in Jerusalem artichoke tuber flour fermentation (200 g L(-1)) at 40 °C achieved by K. marxianus PT-1 and S. cerevisiae JZ1C was 73.6 and 65.2 g L(-1), which corresponded to the theoretical ethanol yield of 90.0 and 79.7 %, respectively. In the range of 30 to 40 °C, temperature did not have a significant effect on ethanol production for both strains. This study displayed the distinctive superiority of K. marxianus PT-1 and S. cerevisiae JZ1C in the thermotolerance and utilization of inulin-type oligosaccharides reserved in Jerusalem artichoke tubers. It is proposed that both K. marxianus and S. cerevisiae have considerable potential in ethanol production from Jerusalem artichoke tubers by a high temperature CBP.

  14. Thermotolerant Kluyveromyces marxianus and Saccharomyces cerevisiae strains representing potentials for bioethanol production from Jerusalem artichoke by consolidated bioprocessing

    Hu, Nan [Agricultural Univ., Qingdao, SD (China). College of Animal Science and Technology; Chinese Academy of Sciences, Qingdao, SD (China). Key Lab. of Biofuels; Yuan, Bo; Wang, Shi-An; Li, Fu-Li [Chinese Academy of Sciences, Qingdao, SD (China). Key Lab. of Biofuels; Sun, Juan [Agricultural Univ., Qingdao, SD (China). College of Animal Science and Technology

    2012-09-15

    Thermotolerant inulin-utilizing yeast strains are desirable for ethanol production from Jerusalem artichoke tubers by consolidated bioprocessing (CBP). To obtain such strains, 21 naturally occurring yeast strains isolated by using an enrichment method and 65 previously isolated Saccharomyces cerevisiae strains were investigated in inulin utilization, extracellular inulinase activity, and ethanol fermentation from inulin and Jerusalem artichoke tuber flour at 40 C. The strains Kluyveromyces marxianus PT-1 (CGMCC AS2.4515) and S. cerevisiae JZ1C (CGMCC AS2.3878) presented the highest extracellular inulinase activity and ethanol yield in this study. The highest ethanol concentration in Jerusalem artichoke tuber flour fermentation (200 g L{sup -1}) at 40 C achieved by K. marxianus PT-1 and S. cerevisiae JZ1C was 73.6 and 65.2 g L{sup -1}, which corresponded to the theoretical ethanol yield of 90.0 and 79.7 %, respectively. In the range of 30 to 40 C, temperature did not have a significant effect on ethanol production for both strains. This study displayed the distinctive superiority of K. marxianus PT-1 and S. cerevisiae JZ1C in the thermotolerance and utilization of inulin-type oligosaccharides reserved in Jerusalem artichoke tubers. It is proposed that both K. marxianus and S. cerevisiae have considerable potential in ethanol production from Jerusalem artichoke tubers by a high temperature CBP. (orig.)

  15. The role of nitrogen uptake on the competition ability of three vineyard Saccharomyces cerevisiae strains.

    Vendramini, Chiara; Beltran, Gemma; Nadai, Chiara; Giacomini, Alessio; Mas, Albert; Corich, Viviana

    2017-10-03

    Three vineyard strains of Saccharomyces cerevisiae, P301.4, P304.4 and P254.12, were assayed in comparison with a commercial industrial strain, QA23. The aim was to understand if nitrogen availability could influence strain competition ability during must fermentation. Pairwise-strain fermentations and co-fermentations with the simultaneous presence of the four strains were performed in synthetic musts at two nitrogen levels: control nitrogen condition (CNC) that assured the suitable assimilable nitrogen amount required by the yeast strains to complete the fermentation and low nitrogen condition (LNC) where nitrogen is present at very low level. Results suggested a strong involvement of nitrogen availability, as the frequency in must of the vineyard strains, respect to QA23, in LNC was always higher than that found in CNC. Moreover, in CNC only strain P304.4 reached the same strain frequency as QA23. P304.4 competition ability increased during the fermentation, indicating better performance when nitrogen availability was dropping down. P301.4 was the only strain sensitive to QA23 killer toxin. In CNC, when it was co-inoculated with the industrial strain QA23, P301.4 was never detected. In LNC, P301.4 after 12h accounted for 10% of the total population. This percentage increased after 48h (20%). Single-strain fermentations were also run in both conditions and the nitrogen metabolism further analyzed. Fermentation kinetics, ammonium and amino-acid consumptions and the expression of genes under nitrogen catabolite repression evidenced that vineyard yeasts, and particularly strain P304.4, had higher nitrogen assimilation rate than the commercial control. In conclusion, the high nitrogen assimilation rate seems to be an additional strategy that allowed vineyard yeasts successful competition during the growth in grape musts. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Raspberry wine fermentation with suspended and immobilized yeast cells of two strains of Saccharomyces cerevisiae.

    Djordjević, Radovan; Gibson, Brian; Sandell, Mari; de Billerbeck, Gustavo M; Bugarski, Branko; Leskošek-Čukalović, Ida; Vunduk, Jovana; Nikićević, Ninoslav; Nedović, Viktor

    2015-01-01

    The objectives of this study were to assess the differences in fermentative behaviour of two different strains of Saccharomyces cerevisiae (EC1118 and RC212) and to determine the differences in composition and sensory properties of raspberry wines fermented with immobilized and suspended yeast cells of both strains at 15 °C. Analyses of aroma compounds, glycerol, acetic acid and ethanol, as well as the kinetics of fermentation and a sensory evaluation of the wines, were performed. All fermentations with immobilized yeast cells had a shorter lag phase and faster utilization of sugars and ethanol production than those fermented with suspended cells. Slower fermentation kinetics were observed in all the samples that were fermented with strain RC212 (suspended and immobilized) than in samples fermented with strain EC1118. Significantly higher amounts of acetic acid were detected in all samples fermented with strain RC212 than in those fermented with strain EC1118 (0.282 and 0.602 g/l, respectively). Slightly higher amounts of glycerol were observed in samples fermented with strain EC1118 than in those fermented with strain RC212. Copyright © 2014 John Wiley & Sons, Ltd.

  17. Physiology of the fuel ethanol strain Saccharomyces cerevisiae PE-2 at low pH indicates a context-dependent performance relevant for industrial applications.

    Della-Bianca, Bianca E; de Hulster, Erik; Pronk, Jack T; van Maris, Antonius J A; Gombert, Andreas K

    2014-12-01

    Selected Saccharomyces cerevisiae strains are used in Brazil to produce the hitherto most energetically efficient first-generation fuel ethanol. Although genome and some transcriptome data are available for some of these strains, quantitative physiological data are lacking. This study investigates the physiology of S. cerevisiae strain PE-2, widely used in the Brazilian fuel ethanol industry, in comparison with CEN.PK113-7D, a reference laboratory strain, focusing on tolerance to low pH and acetic acid stress. Both strains were grown in anaerobic bioreactors, operated as batch, chemostat or dynamic continuous cultures. Despite their different backgrounds, biomass and product formation by the two strains were similar under a range of conditions (pH 5 or pH cells, incubated at pH 1.5, indicated a superior survival of glucose-depleted PE-2 cells, when compared with either CEN.PK113-7D or a commercial bakers' strain. These results indicate that the sulfuric acid washing step, used in the fuel ethanol industry to decrease bacterial contamination due to non-aseptic operation, might have exerted an important selective pressure on the microbial populations present in such environments. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  18. Laboratory evolution of a biotin-requiring Saccharomyces cerevisiae strain for full biotin prototrophy and identification of causal mutations

    Bracher, J.M.; de Hulster, A.F.; van den Broek, M.A.; Daran, J.G.; van Maris, A.J.A.; Pronk, J.T.

    2017-01-01

    Biotin prototrophy is a rare, incompletely understood, and industrially relevant characteristic of Saccharomyces cerevisiae strains. The genome of the haploid laboratory strain CEN.PK113-7D contains a full complement of biotin biosynthesis genes, but its growth in biotin-free synthetic medium is

  19. Substrate-Limited Saccharomyces cerevisiae Yeast Strains Allow Control of Fermentation during Bread Making.

    Struyf, Nore; Laurent, Jitka; Verspreet, Joran; Verstrepen, Kevin J; Courtin, Christophe M

    2017-04-26

    Identification and use of yeast strains that are unable to consume one or more otherwise fermentable substrate types could allow a more controlled fermentation process with more flexibility regarding fermentation times. In this study, Saccharomyces cerevisiae strains with different capacities to consume substrates present in wheat were selected to investigate the impact of substrate limitation on dough fermentation and final bread volume. Results show that fermentation of dough with maltose-negative strains relies on the presence of fructan and sucrose as fermentable substrates and can be used for regular bread making. Levels of fructan and sucrose, endogenously present or added, hence determine the extent of fermentation and timing at the proofing stage. Whole meal is inherently more suitable for substrate-limited fermentation than white flour due to the presence of higher native levels of these substrates. Bread making protocols with long fermentation times are accommodated by addition of substrates such as sucrose.

  20. Breeding of a xylose-fermenting hybrid strain by mating genetically engineered haploid strains derived from industrial Saccharomyces cerevisiae.

    Inoue, Hiroyuki; Hashimoto, Seitaro; Matsushika, Akinori; Watanabe, Seiya; Sawayama, Shigeki

    2014-12-01

    The industrial Saccharomyces cerevisiae IR-2 is a promising host strain to genetically engineer xylose-utilizing yeasts for ethanol fermentation from lignocellulosic hydrolysates. Two IR-2-based haploid strains were selected based upon the rate of xylulose fermentation, and hybrids were obtained by mating recombinant haploid strains harboring heterogeneous xylose dehydrogenase (XDH) (wild-type NAD(+)-dependent XDH or engineered NADP(+)-dependent XDH, ARSdR), xylose reductase (XR) and xylulose kinase (XK) genes. ARSdR in the hybrids selected for growth rates on yeast extract-peptone-dextrose (YPD) agar and YP-xylose agar plates typically had a higher activity than NAD(+)-dependent XDH. Furthermore, the xylose-fermenting performance of the hybrid strain SE12 with the same level of heterogeneous XDH activity was similar to that of a recombinant strain of IR-2 harboring a single set of genes, XR/ARSdR/XK. These results suggest not only that the recombinant haploid strains retain the appropriate genetic background of IR-2 for ethanol production from xylose but also that ARSdR is preferable for xylose fermentation.

  1. Impact of Commercial Strain Use on Saccharomyces cerevisiae Population Structure and Dynamics in Pinot Noir Vineyards and Spontaneous Fermentations of a Canadian Winery.

    Jonathan T Martiniuk

    Full Text Available 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.

  2. Impact of Commercial Strain Use on Saccharomyces cerevisiae Population Structure and Dynamics in Pinot Noir Vineyards and Spontaneous Fermentations of a Canadian Winery.

    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.

  3. The Geographic Distribution of Saccharomyces cerevisiae Isolates within three Italian Neighboring Winemaking Regions Reveals Strong Differences in Yeast Abundance, Genetic Diversity and Industrial Strain Dissemination

    Alessia Viel

    2017-08-01

    Full Text Available In recent years the interest for natural fermentations has been re-evaluated in terms of increasing the wine terroir and managing more sustainable winemaking practices. Therefore, the level of yeast genetic variability and the abundance of Saccharomyces cerevisiae native populations in vineyard are becoming more and more crucial at both ecological and technological level. Among the factors that can influence the strain diversity, the commercial starter release that accidentally occur in the environment around the winery, has to be considered. In this study we led a wide scale investigation of S. cerevisiae genetic diversity and population structure in the vineyards of three neighboring winemaking regions of Protected Appellation of Origin, in North-East of Italy. Combining mtDNA RFLP and microsatellite markers analyses we evaluated 634 grape samples collected over 3 years. We could detect major differences in the presence of S. cerevisiae yeasts, according to the winemaking region. The population structures revealed specificities of yeast microbiota at vineyard scale, with a relative Appellation of Origin area homogeneity, and transition zones suggesting a geographic differentiation. Surprisingly, we found a widespread industrial yeast dissemination that was very high in the areas where the native yeast abundance was low. Although geographical distance is a key element involved in strain distribution, the high presence of industrial strains in vineyard reduced the differences between populations. This finding indicates that industrial yeast diffusion it is a real emergency and their presence strongly interferes with the natural yeast microbiota.

  4. Construction of novel Saccharomyces cerevisiae strains for bioethanol active dry yeast (ADY) production.

    Zheng, Daoqiong; Zhang, Ke; Gao, Kehui; Liu, Zewei; Zhang, Xing; Li, Ou; Sun, Jianguo; Zhang, Xiaoyang; Du, Fengguang; Sun, Peiyong; Qu, Aimin; Wu, Xuechang

    2013-01-01

    The application of active dry yeast (ADY) in bioethanol production simplifies operation processes and reduces the risk of bacterial contamination. In the present study, we constructed a novel ADY strain with improved stress tolerance and ethanol fermentation performances under stressful conditions. The industrial Saccharomyces cerevisiae strain ZTW1 showed excellent properties and thus subjected to a modified whole-genome shuffling (WGS) process to improve its ethanol titer, proliferation capability, and multiple stress tolerance for ADY production. The best-performing mutant, Z3-86, was obtained after three rounds of WGS, producing 4.4% more ethanol and retaining 2.15-fold higher viability than ZTW1 after drying. Proteomics and physiological analyses indicated that the altered expression patterns of genes involved in protein metabolism, plasma membrane composition, trehalose metabolism, and oxidative responses contribute to the trait improvement of Z3-86. This work not only successfully developed a novel S. cerevisiae mutant for application in commercial bioethanol production, but also enriched the current understanding of how WGS improves the complex traits of microbes.

  5. Construction of novel Saccharomyces cerevisiae strains for bioethanol active dry yeast (ADY production.

    Daoqiong Zheng

    Full Text Available The application of active dry yeast (ADY in bioethanol production simplifies operation processes and reduces the risk of bacterial contamination. In the present study, we constructed a novel ADY strain with improved stress tolerance and ethanol fermentation performances under stressful conditions. The industrial Saccharomyces cerevisiae strain ZTW1 showed excellent properties and thus subjected to a modified whole-genome shuffling (WGS process to improve its ethanol titer, proliferation capability, and multiple stress tolerance for ADY production. The best-performing mutant, Z3-86, was obtained after three rounds of WGS, producing 4.4% more ethanol and retaining 2.15-fold higher viability than ZTW1 after drying. Proteomics and physiological analyses indicated that the altered expression patterns of genes involved in protein metabolism, plasma membrane composition, trehalose metabolism, and oxidative responses contribute to the trait improvement of Z3-86. This work not only successfully developed a novel S. cerevisiae mutant for application in commercial bioethanol production, but also enriched the current understanding of how WGS improves the complex traits of microbes.

  6. Genome-Wide Analysis of the TORC1 and Osmotic Stress Signaling Network in Saccharomyces cerevisiae

    Jeremy Worley

    2016-02-01

    Full Text Available The Target of Rapamycin kinase Complex I (TORC1 is a master regulator of cell growth and metabolism in eukaryotes. Studies in yeast and human cells have shown that nitrogen/amino acid starvation signals act through Npr2/Npr3 and the small GTPases Gtr1/Gtr2 (Rags in humans to inhibit TORC1. However, it is unclear how other stress and starvation stimuli inhibit TORC1, and/or act in parallel with the TORC1 pathway, to control cell growth. To help answer these questions, we developed a novel automated pipeline and used it to measure the expression of a TORC1-dependent ribosome biogenesis gene (NSR1 during osmotic stress in 4700 Saccharomyces cerevisiae strains from the yeast knock-out collection. This led to the identification of 440 strains with significant and reproducible defects in NSR1 repression. The cell growth control and stress response proteins deleted in these strains form a highly connected network, including 56 proteins involved in vesicle trafficking and vacuolar function; 53 proteins that act downstream of TORC1 according to a rapamycin assay—including components of the HDAC Rpd3L, Elongator, and the INO80, CAF-1 and SWI/SNF chromatin remodeling complexes; over 100 proteins involved in signaling and metabolism; and 17 proteins that directly interact with TORC1. These data provide an important resource for labs studying cell growth control and stress signaling, and demonstrate the utility of our new, and easily adaptable, method for mapping gene regulatory networks.

  7. Saccharomyces cerevisiae vineyard strains have different nitrogen requirements that affect their fermentation performances.

    Lemos Junior, W J F; Viel, A; Bovo, B; Carlot, M; Giacomini, A; Corich, V

    2017-11-01

    In this work the fermentation performances of seven vineyard strains, together with the industrial strain EC1118, have been investigated at three differing yeast assimilable nitrogen (YAN) concentrations (300 mg N l -1 , 150 mg N l -1 and 70 mg N l -1 ) in synthetic musts. The results indicated that the response to different nitrogen levels is strain dependent. Most of the strains showed a dramatic decrease of the fermentation at 70 mg N l -1 but no significant differences in CO 2 production were found when fermentations at 300 mg N l -1 and 150 mg N l -1 were compared. Only one among the vineyard strains showed a decrease of the fermentation when 150 mg N l -1 were present in the must. These results contribute to shed light on strain nitrogen requirements and offer new perspectives to manage the fermentation process during winemaking. Selected vineyard Saccharomyces cerevisiae strains can improve the quality and the complexity of local wines. Wine quality is also influenced by nitrogen availability that modulates yeast fermentation activity. In this work, yeast nitrogen assimilation was evaluated to clarify the nitrogen requirements of vineyard strains. Most of the strains needed high nitrogen levels to express the best fermentation performances. The results obtained indicate the critical nitrogen levels. When the nitrogen concentration was above the critical level, the fermentation process increased, but if the level of nitrogen was further increased no effect on the fermentation was found. © 2017 The Society for Applied Microbiology.

  8. Increased ethanol accumulation from glucose via reduction of ATP level in a recombinant strain of Saccharomyces cerevisiae overexpressing alkaline phosphatase.

    Semkiv, Marta V; Dmytruk, Kostyantyn V; Abbas, Charles A; Sibirny, Andriy A

    2014-05-15

    The production of ethyl alcohol by fermentation represents the largest scale application of Saccharomyces cerevisiae in industrial biotechnology. Increased worldwide demand for fuel bioethanol is anticipated over the next decade and will exceed 200 billion liters from further expansions. Our working hypothesis was that the drop in ATP level in S. cerevisiae cells during alcoholic fermentation should lead to an increase in ethanol production (yield and productivity) with a greater amount of the utilized glucose converted to ethanol. Our approach to achieve this goal is to decrease the intracellular ATP level via increasing the unspecific alkaline phosphatase activity. Intact and truncated versions of the S. cerevisiae PHO8 gene coding for vacuolar or cytosolic forms of alkaline phosphatase were fused with the alcohol dehydrogenase gene (ADH1) promoter. The constructed expression cassettes used for transformation vectors also contained the dominant selective marker kanMX4 and S. cerevisiae δ-sequence to facilitate multicopy integration to the genome. Laboratory and industrial ethanol producing strains BY4742 and AS400 overexpressing vacuolar form of alkaline phosphatase were characterized by a slightly lowered intracellular ATP level and biomass accumulation and by an increase in ethanol productivity (13% and 7%) when compared to the parental strains. The strains expressing truncated cytosolic form of alkaline phosphatase showed a prolonged lag-phase, reduced biomass accumulation and a strong defect in ethanol production. Overexpression of vacuolar alkaline phosphatase leads to an increased ethanol yield in S. cerevisiae.

  9. Ecological survey of Saccharomyces cerevisiae strains from vineyards in the Vinho Verde Region of Portugal.

    Schuller, Dorit; Alves, Hugo; Dequin, Sylvie; Casal, Margarida

    2005-01-01

    One thousand six hundred and twenty yeast isolates were obtained from 54 spontaneous fermentations performed from grapes collected in 18 sampling sites of three vineyards (Vinho Verde Wine Region in northwest Portugal) during the 2001-2003 harvest seasons. All isolates were analyzed by mitochondrial DNA restriction fragment length polymorphism (mtDNA RFLP) and a pattern profile was verified for each isolate, resulting in a total of 297 different profiles, that all belonged to the species Saccharomyces cerevisiae. The strains corresponding to seventeen profiles showed a wider temporal and geographical distribution, being characterized by a generalized pattern of sporadic presence, absence and reappearance. One strain (ACP10) showed a more regional distribution with a perennial behavior. In different fermentations ACP10 was either dominant or not, showing that the final outcome of fermentation was dependent on the specific composition of the yeast community in the must. Few of the grape samples collected before harvest initiated a spontaneous fermentation, compared to the samples collected after harvest, in a time frame of about 2 weeks. The associated strains were also much more diversified: 267 patterns among 1260 isolates compared to 30 patterns among 360 isolates in the post- and pre-harvest samples, respectively. Fermenting yeast populations have never been characterized before in this region and the present work reports the presence of commercial yeast strains used by the wineries. The present study aims at the development of strategies for the preservation of biodiversity and genetic resources as a basis for further strain development.

  10. Haploid deletion strains of Saccharomyces cerevisiae that determine survival during space flight

    Johanson, Kelly; Allen, Patricia L.; Gonzalez-Villalobos, Romer A.; Nesbit, Jacqueline; Nickerson, Cheryl A.; Höner zu Bentrup, Kerstin; Wilson, James W.; Ramamurthy, Rajee; D'Elia, Riccardo; Muse, Kenneth E.; Hammond, Jeffrey; Freeman, Jake; Stodieck, Louis S.; Hammond, Timothy G.

    2007-02-01

    This study identifies genes that determine survival during a space flight, using the model eukaryotic organism, Saccharomyces cerevisiae. Select strains of a haploid yeast deletion series grew during storage in distilled water in space, but not in ground based static or clinorotation controls. The survival advantages in space in distilled water include a 133-fold advantage for the deletion of PEX19, a chaperone and import receptor for newly- synthesized class I peroxisomal membrane proteins, to 77-40 fold for deletion strains lacking elements of aerobic respiration, isocitrate metabolism, and mitochondrial electron transport. Following automated addition of rich growth media, the space flight was associated with a marked survival advantage of strains with deletions in catalytically active genes including hydrolases, oxidoreductases and transferases. When compared to static controls, space flight was associated with a marked survival disadvantage of deletion strains lacking transporter, antioxidant and catalytic activity. This study identifies yeast deletion strains with a survival advantage during storage in distilled water and space flight, and amplifies our understanding of the genes critical for survival in space.

  11. Molecular and Technological Characterization of Saccharomyces cerevisiae Strains Isolated from Natural Fermentation of Susumaniello Grape Must in Apulia, Southern Italy

    Mariana Tristezza

    2014-01-01

    Full Text Available The characterization of autochthonous Saccharomyces cerevisiae strains is an important step towards the conservation and employment of microbial biodiversity. The utilization of selected autochthonous yeast strains would be a powerful tool to enhance the organoleptic and sensory properties of typical regional wines. In fact, indigenous yeasts are better tailored to a particular must and because of this they are able to praise the peculiarities of the derived wine. The present study described the biodiversity of indigenous S. cerevisiae strains isolated from natural must fermentations of an ancient and recently rediscovered Apulian grape cultivar, denoted as “Susumaniello.” The yeast strains denoted by the best oenological and technological features were identified and their fermentative performances were tested by either laboratory assay. Five yeast strains showed that they could be excellent candidates for the production of industrial starter cultures, since they dominated the fermentation process and produced wines characterized by peculiar oenological and organoleptic features.

  12. Co-utilization of L-arabinose and D-xylose by laboratory and industrial Saccharomyces cerevisiae strains

    Boles Eckhard

    2006-04-01

    Full Text Available Abstract Background Fermentation of lignocellulosic biomass is an attractive alternative for the production of bioethanol. Traditionally, the yeast Saccharomyces cerevisiae is used in industrial ethanol fermentations. However, S. cerevisiae is naturally not able to ferment the pentose sugars D-xylose and L-arabinose, which are present in high amounts in lignocellulosic raw materials. Results We describe the engineering of laboratory and industrial S. cerevisiae strains to co-ferment the pentose sugars D-xylose and L-arabinose. Introduction of a fungal xylose and a bacterial arabinose pathway resulted in strains able to grow on both pentose sugars. Introduction of a xylose pathway into an arabinose-fermenting laboratory strain resulted in nearly complete conversion of arabinose into arabitol due to the L-arabinose reductase activity of the xylose reductase. The industrial strain displayed lower arabitol yield and increased ethanol yield from xylose and arabinose. Conclusion Our work demonstrates simultaneous co-utilization of xylose and arabinose in recombinant strains of S. cerevisiae. In addition, the co-utilization of arabinose together with xylose significantly reduced formation of the by-product xylitol, which contributed to improved ethanol production.

  13. Quantitative Genome-Wide Analysis of Yeast Deletion Strain Sensitivities to Oxidative and Chemical Stress

    Stanley Fields

    2006-03-01

    Full Text Available Understanding the actions of drugs and toxins in a cell is of critical importance to medicine, yet many of the molecular events involved in chemical resistance are relatively uncharacterized. In order to identify the cellular processes and pathways targeted by chemicals, we took advantage of the haploid Saccharomyces cerevisiae deletion strains (Winzeler et al., 1999. Although ~4800 of the strains are viable, the loss of a gene in a pathway affected by a drug can lead to a synthetic lethal effect in which the combination of a deletion and a normally sublethal dose of a chemical results in loss of viability. WE carried out genome-wide screens to determine quantitative sensitivities of the deletion set to four chemicals: hydrogen peroxide, menadione, ibuprofen and mefloquine. Hydrogen peroxide and menadione induce oxidative stress in the cell, whereas ibuprofen and mefloquine are toxic to yeast by unknown mechanisms. Here we report the sensitivities of 659 deletion strains that are sensitive to one or more of these four compounds, including 163 multichemicalsensitive strains, 394 strains specific to hydrogen peroxide and/or menadione, 47 specific to ibuprofen and 55 specific to mefloquine.We correlate these results with data from other large-scale studies to yield novel insights into cellular function.

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

    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.

  15. CRISPR–Cas system enables fast and simple genome editing of industrial Saccharomyces cerevisiae strains

    Vratislav Stovicek

    2015-12-01

    Full Text Available There is a demand to develop 3rd generation biorefineries that integrate energy production with the production of higher value chemicals from renewable feedstocks. Here, robust and stress-tolerant industrial strains of Saccharomyces cerevisiae will be suitable production organisms. However, their genetic manipulation is challenging, as they are usually diploid or polyploid. Therefore, there is a need to develop more efficient genetic engineering tools. We applied a CRISPR–Cas9 system for genome editing of different industrial strains, and show simultaneous disruption of two alleles of a gene in several unrelated strains with the efficiency ranging between 65% and 78%. We also achieved simultaneous disruption and knock-in of a reporter gene, and demonstrate the applicability of the method by designing lactic acid-producing strains in a single transformation event, where insertion of a heterologous gene and disruption of two endogenous genes occurred simultaneously. Our study provides a foundation for efficient engineering of industrial yeast cell factories. Keywords: CRISPR–Cas9, Genome editing, Industrial yeast, Biorefineries, Chemical production

  16. Impact of Saccharomyces cerevisiae Strains on Health-Promoting Compounds in Wine

    Simona Guerrini

    2018-04-01

    Full Text Available Moderate wine consumption is associated with human health benefits (reduction of cardiovascular risk and neurodegenerative diseases, decrease of onset of certain cancers attributed to a series of bioactive compounds, mainly polyphenols, with antioxidant power capable of counteracting the negative action of free radicals. Polyphenols are naturally present in the grapes, but an additional amount originates during winemaking. The aim of this work was to assess the ability of four commercial and two indigenous Saccharomyces cerevisiae strains to produce bioactive compounds (tyrosol, hydroxytyrosol, tryptophol, melatonin and glutathione during alcoholic fermentation. In order to exclude the fraction of antioxidant compounds naturally occurring in grapes, the strains were inoculated in a synthetic must. At the end of fermentation the bioactive compounds were analysed by High-Performance Liquid Chromatography, while antioxidant activity was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH assay. Moreover, freeze-dried samples, originating from the experimental wines, were used to perform ex-vivo assays on cultured cells (RAW 264.7 murine macrophages with the aim to evaluate their antioxidant and anti-inflammatory activities. The results indicated that the production of the considered bioactive compounds is a strain-specific property; therefore, the different yeast strains utilized during fermentation have different capabilities to modify the antioxidant and anti-inflammatory properties of the wine.

  17. Production of fructanase by a wild strain of Saccharomyces cerevisiae on tequila agave fructan.

    Corona-González, R I; Pelayo-Ortiz, C; Jacques, G; Guatemala, G; Arriola, E; Arias, J A; Toriz, G

    2015-01-01

    A new wild strain of Saccharomyces cerevisiae (CF3) isolated from tequila must was evaluated for production of fructanase on Agave tequilana Weber fructan (FT). Fructanase activity (F) was assessed by a 3(3) factorial design (substrate, temperature and pH). High enzymatic activity (31.1 U/ml) was found at 30 °C, pH 5, using FT (10 g/l) as substrate. The effect of initial substrate concentration on F (FT0, 5.7-66 g/l) was studied and it was found that F was highest (44.8 U/ml) at FT0 25 g/l. A 2(2) factorial experimental design with five central points was utilized to study the effect of stirring and aeration on fructanase activity; stirring exhibited a stronger effect on F. The ratio fructanase to invertase (F/S) was 0.57, which confirms that the enzymes are fructanase. Crude fructanase reached high substrate hydrolysis (48 wt%) in 10 h. It is shown that S. cerevisiae CF3 was able to produce large amounts of fructanase by growing it on fructan from A. tequilana.

  18. Key Process Conditions for Production of C4 Dicarboxylic Acids in Bioreactor Batch Cultures of an Engineered Saccharomyces cerevisiae Strain

    Zelle, R.M.; De Hulster, E.; Kloezen, W.; Pronk, J.T.; Van Maris, A.J.A.

    2010-01-01

    A recent effort to improve malic acid production by Saccharomyces cerevisiae by means of metabolic engineering resulted in a strain that produced up to 59 g liter(-1) of malate at a yield of 0.42 mol (mol glucose)(-1) in calcium carbonate-buffered shake flask cultures. With shake flasks, process

  19. Wine yeast phenomics: A standardized fermentation method for assessing quantitative traits of Saccharomyces cerevisiae strains in enological conditions

    Bernard, Margaux; Trujillo, Marine; Prodhomme, Duyên; Barbe, Jean-Christophe; Gibon, Yves; Marullo, Philippe

    2018-01-01

    This work describes the set up of a small scale fermentation methodology for measuring quantitative traits of hundreds of samples in an enological context. By using standardized screw cap vessels, the alcoholic fermentation kinetics of Saccharomyces cerevisiae strains were measured by following their weight loss over the time. This dispositive was coupled with robotized enzymatic assays for measuring metabolites of enological interest in natural grape juices. Despite the small volume used, kinetic parameters and fermentation end products measured are similar with those observed in larger scale vats. The vessel used also offers the possibility to assay 32 volatiles compounds using a headspace solid-phase micro-extraction coupled to gas chromatography and mass spectrometry. The vessel shaking applied strongly impacted most of the phenotypes investigated due to oxygen transfer occuring in the first hours of the alcoholic fermentation. The impact of grape must and micro-oxygenation was investigated illustrating some relevant genetic x environmental interactions. By phenotyping a wide panel of commercial wine starters in five grape juices, broad phenotypic correlations between kinetics and metabolic end products were evidentiated. Moreover, a multivariate analysis illustrates that some grape musts are more able than others to discriminate commercial strains since some are less robust to environmental changes. PMID:29351285

  20. Wine yeast phenomics: A standardized fermentation method for assessing quantitative traits of Saccharomyces cerevisiae strains in enological conditions.

    Peltier, Emilien; Bernard, Margaux; Trujillo, Marine; Prodhomme, Duyên; Barbe, Jean-Christophe; Gibon, Yves; Marullo, Philippe

    2018-01-01

    This work describes the set up of a small scale fermentation methodology for measuring quantitative traits of hundreds of samples in an enological context. By using standardized screw cap vessels, the alcoholic fermentation kinetics of Saccharomyces cerevisiae strains were measured by following their weight loss over the time. This dispositive was coupled with robotized enzymatic assays for measuring metabolites of enological interest in natural grape juices. Despite the small volume used, kinetic parameters and fermentation end products measured are similar with those observed in larger scale vats. The vessel used also offers the possibility to assay 32 volatiles compounds using a headspace solid-phase micro-extraction coupled to gas chromatography and mass spectrometry. The vessel shaking applied strongly impacted most of the phenotypes investigated due to oxygen transfer occuring in the first hours of the alcoholic fermentation. The impact of grape must and micro-oxygenation was investigated illustrating some relevant genetic x environmental interactions. By phenotyping a wide panel of commercial wine starters in five grape juices, broad phenotypic correlations between kinetics and metabolic end products were evidentiated. Moreover, a multivariate analysis illustrates that some grape musts are more able than others to discriminate commercial strains since some are less robust to environmental changes.

  1. Genome wide transcriptional response of Saccharomyces cerevisiae to stress-induced perturbations

    Hilal eTaymaz-Nikerel

    2016-02-01

    Full Text Available Cells respond to environmental and/or genetic perturbations in order to survive and proliferate. Characterization of the changes after various stimuli at different -omics levels is crucial to comprehend the adaptation of cells to changing conditions. Genome wide quantification and analysis of transcript levels, the genes affected by perturbations, extends our understanding of cellular metabolism by pointing out the mechanisms that play role in sensing the stress caused by those perturbations and related signaling pathways, and in this way guides us to achieve endeavors such as rational engineering of cells or interpretation of disease mechanisms. Saccharomyces cerevisiae as a model system has been studied in response to different perturbations and corresponding transcriptional profiles were followed either statically or/and dynamically, short- and long- term. This review focuses on response of yeast cells to diverse stress inducing perturbations including nutritional changes, ionic stress, salt stress, oxidative stress, osmotic shock, as well as to genetic interventions such as deletion and over-expression of genes. It is aimed to conclude on common regulatory phenomena that allow yeast to organize its transcriptomic response after any perturbation under different external conditions.

  2. IMPROVEMENT OF BORASSUS AKEASSII WINES QUALITY BY CONTROLLED FERMENTATION USING SACCHAROMYCES CEREVISIAE STRAINS

    TAPSOBA François

    2016-06-01

    Full Text Available Palm wine produced traditionally and consumed by many people around the world and specifically in Burkina Faso posed health risks because of questionable quality of wine produced by mix culture fermentation and the use of antiseptics for the stabilization. In order to improve its quality, Saccharomyces cerevisiae strains isolated from Borassus akeassii wines and identified by amplification and RFLP analysis of the 5-8S-ITS region were used for in vitro fermentation of unfermented palm sap. The physicochemical characteristics of the sap were measured before and after fermentation process by High-Performance Liquid Chromatography (HPLC and the microbiological quality were also performed. HPLC analysis showed that glucose and fructose concentration in palm sap were 37.0 and 27.6 g/L respectively, ethanol content was ranged between 2.76 and 5.31 % (g/mL for controlled fermentation and 2.20 % (g/mL for spontaneous fermentation. Lactic and acetic acids were ranged between 0.1 and 0.3 g/L and 1.5 and 1.6 g/L for controlled fermentation versus 2.5 and 3.1 g/L and the spontaneous fermentation respectively. Coliforms and Staphylococcus aureus were detected only in the unfermented palm sap and the wine fermented spontaneously. Principal component analysis showed a good separation between spontaneous and controlled fermentation. Sterilization and controlled fermentation of the unfermented sap with palm wine Saccharomyces cerevisiae strains led to the improvement of palm wine quality.

  3. Development Of An Efficient Glycerol Utilizing Saccharomyces Cerevisiae Strain Via Adaptive Laboratory Evolution

    Strucko, Tomas; Zirngibl, Katharina; Tharwat Tolba Mohamed, Elsayed

    2015-01-01

    that popular wild-type laboratory yeast strains, commonly applied in metabolic engineering studies, did not grow or grew very slowly in glycerol medium.In this work, an adaptive laboratory evolution approach to obtain S. cerevisiae strains with an improved ability to grow on glycerol was applied. A broad array...... of evolved strains, which exhibited a significant increase in the specific growth rate and a higher glycerol consumption rate, were isolated. The best performing strains were further analyzed by classical genetics and whole genome re-sequencing in order to understand the molecular basis of glycerol...

  4. An ultrasensitive strain sensor with a wide strain range based on graphene armour scales.

    Yang, Yi-Fan; Tao, Lu-Qi; Pang, Yu; Tian, He; Ju, Zhen-Yi; Wu, Xiao-Ming; Yang, Yi; Ren, Tian-Ling

    2018-06-12

    An ultrasensitive strain sensor with a wide strain range based on graphene armour scales is demonstrated in this paper. The sensor shows an ultra-high gauge factor (GF, up to 1054) and a wide strain range (ε = 26%), both of which present an advantage compared to most other flexible sensors. Moreover, the sensor is developed by a simple fabrication process. Due to the excellent performance, this strain sensor can meet the demands of subtle, large and complex human motion monitoring, which indicates its tremendous application potential in health monitoring, mechanical control, real-time motion monitoring and so on.

  5. Biodiversity of autolytic ability in flocculent Saccharomyces cerevisiae strains suitable for traditional sparkling wine fermentation.

    Perpetuini, Giorgia; Di Gianvito, Paola; Arfelli, Giuseppe; Schirone, Maria; Corsetti, Aldo; Tofalo, Rosanna; Suzzi, Giovanna

    2016-07-01

    Yeasts involved in secondary fermentation of traditional sparkling wines should show specific characteristics, such as flocculation capacity and autolysis. Recently it has been postulated that autophagy may contribute to the outcome of autolysis. In this study, 28 flocculent wine Saccahromyces cerevisiae strains characterized by different flocculation degrees were studied for their autolytic and autophagic activities. Autolysis was monitored in synthetic medium through the determination of amino acid nitrogen and total proteins released. At the same time, novel primer sets were developed to determine the expression of the genes ATG1, ATG17 and ATG29. Twelve strains were selected on the basis of their autolytic rate and ATG gene expressions in synthetic medium and were inoculated in a base wine. After 30, 60 and 180 days the autolytic process and ATG gene expressions were evaluated. The obtained data showed that autolysis and ATG gene expressions differed among strains and were independent of the degree of flocculation. This biodiversity could be exploited to select new starter stains to improve sparkling wine production. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  6. Xylose fermentation efficiency and inhibitor tolerance of the recombinant industrial Saccharomyces cerevisiae strain NAPX37.

    Li, Yun-Cheng; Mitsumasu, Kanako; Gou, Zi-Xi; Gou, Min; Tang, Yue-Qin; Li, Guo-Ying; Wu, Xiao-Lei; Akamatsu, Takashi; Taguchi, Hisataka; Kida, Kenji

    2016-02-01

    Industrial yeast strains with good xylose fermentation ability and inhibitor tolerance are important for economical lignocellulosic bioethanol production. The flocculating industrial Saccharomyces cerevisiae strain NAPX37, harboring the xylose reductase-xylitol dehydrogenase (XR-XDH)-based xylose metabolic pathway, displayed efficient xylose fermentation during batch and continuous fermentation. During batch fermentation, the xylose consumption rates at the first 36 h were similar (1.37 g/L/h) when the initial xylose concentrations were 50 and 75 g/L, indicating that xylose fermentation was not inhibited even when the xylose concentration was as high as 75 g/L. The presence of glucose, at concentrations of up to 25 g/L, did not affect xylose consumption rate at the first 36 h. Strain NAPX37 showed stable xylose fermentation capacity during continuous ethanol fermentation using xylose as the sole sugar, for almost 1 year. Fermentation remained stable at a dilution rate of 0.05/h, even though the xylose concentration in the feed was as high as 100 g/L. Aeration rate, xylose concentration, and MgSO4 concentration were found to affect xylose consumption and ethanol yield. When the xylose concentration in the feed was 75 g/L, a high xylose consumption rate of 6.62 g/L/h and an ethanol yield of 0.394 were achieved under an aeration rate of 0.1 vvm, dilution rate of 0.1/h, and 5 mM MgSO4. In addition, strain NAPX37 exhibited good tolerance to inhibitors such as weak acids, furans, and phenolics during xylose fermentation. These findings indicate that strain NAPX37 is a promising candidate for application in the industrial production of lignocellulosic bioethanol.

  7. Modern technology homogenizes enological traits of indigenous Saccharomyces cerevisiae strains associated with Msalais, a traditional wine in China.

    Zhu, Lixia; Xue, Julan

    2017-03-01

    In this study, we performed a pilot-scale evaluation of the enological characteristics of indigenous Saccharomyces cerevisiae strains associated with Msalais, a traditional Chinese wine produced by a unique technology of boiling grape juice prior to spontaneous fermentation. Technical and sensory characteristics of top ten indigenous strains previously identified by us by screening a collection of 436 indigenous S. cerevisiae strains (Zhu et al. 2016) were assayed in a traditional craft workshop (TCW) and a modern plant (MP). The use of these strains reduced the spontaneous fermentation (Spo F) period by 6-15 days, and resulted in higher sugar and lower alcohol content in TCW Msalais than in MP Msalais. Sensory scores of Msalais fermented by the ten strains were higher than those of wine produced with a commercial strain cy3079, varying in TCW fermentations and significantly different from Spo F, but homogenous for all MP fermentations. Four strains were extensively screened for use in industrial Msalais production. We conclude that modern technology homogenizes enological traits of indigenous strains while traditional craftsmanship maintains their enological diversity. Some strains domesticated in the course of both processes are suitable for industrial Msalais production.

  8. Engineering of a novel Saccharomyces cerevisiae wine strain with a respiratory phenotype at high external glucose concentrations.

    Henricsson, C; de Jesus Ferreira, M C; Hedfalk, K; Elbing, K; Larsson, C; Bill, R M; Norbeck, J; Hohmann, S; Gustafsson, L

    2005-10-01

    The recently described respiratory strain Saccharomyces cerevisiae KOY.TM6*P is, to our knowledge, the only reported strain of S. cerevisiae which completely redirects the flux of glucose from ethanol fermentation to respiration, even at high external glucose concentrations (27). In the KOY.TM6*P strain, portions of the genes encoding the predominant hexose transporter proteins, Hxt1 and Hxt7, were fused within the regions encoding transmembrane (TM) domain 6. The resulting chimeric gene, TM6*, encoded a chimera composed of the amino-terminal half of Hxt1 and the carboxy-terminal half of Hxt7. It was subsequently integrated into the genome of an hxt null strain. In this study, we have demonstrated the transferability of this respiratory phenotype to the V5 hxt1-7Delta strain, a derivative of a strain used in enology. We also show by using this mutant that it is not necessary to transform a complete hxt null strain with the TM6* construct to obtain a non-ethanol-producing phenotype. The resulting V5.TM6*P strain, obtained by transformation of the V5 hxt1-7Delta strain with the TM6* chimeric gene, produced only minor amounts of ethanol when cultured on external glucose concentrations as high as 5%. Despite the fact that glucose flux was reduced to 30% in the V5.TM6*P strain compared with that of its parental strain, the V5.TM6*P strain produced biomass at a specific rate as high as 85% that of the V5 wild-type strain. Even more relevant for the potential use of such a strain for the production of heterologous proteins and also of low-alcohol beverages is the observation that the biomass yield increased 50% with the mutant compared to its parental strain.

  9. Genome-wide analysis reveals the vacuolar pH-stat of Saccharomyces cerevisiae.

    Christopher L Brett

    Full Text Available Protons, the smallest and most ubiquitous of ions, are central to physiological processes. Transmembrane proton gradients drive ATP synthesis, metabolite transport, receptor recycling and vesicle trafficking, while compartmental pH controls enzyme function. Despite this fundamental importance, the mechanisms underlying pH homeostasis are not entirely accounted for in any organelle or organism. We undertook a genome-wide survey of vacuole pH (pH(v in 4,606 single-gene deletion mutants of Saccharomyces cerevisiae under control, acid and alkali stress conditions to reveal the vacuolar pH-stat. Median pH(v (5.27±0.13 was resistant to acid stress (5.28±0.14 but shifted significantly in response to alkali stress (5.83±0.13. Of 107 mutants that displayed aberrant pH(v under more than one external pH condition, functional categories of transporters, membrane biogenesis and trafficking machinery were significantly enriched. Phospholipid flippases, encoded by the family of P4-type ATPases, emerged as pH regulators, as did the yeast ortholog of Niemann Pick Type C protein, implicated in sterol trafficking. An independent genetic screen revealed that correction of pH(v dysregulation in a neo1(ts mutant restored viability whereas cholesterol accumulation in human NPC1(-/- fibroblasts diminished upon treatment with a proton ionophore. Furthermore, while it is established that lumenal pH affects trafficking, this study revealed a reciprocal link with many mutants defective in anterograde pathways being hyperacidic and retrograde pathway mutants with alkaline vacuoles. In these and other examples, pH perturbations emerge as a hitherto unrecognized phenotype that may contribute to the cellular basis of disease and offer potential therapeutic intervention through pH modulation.

  10. Biotechnological process for obtaining new fermented products from cashew apple fruit by Saccharomyces cerevisiae strains.

    Araújo, Suzane Macêdo; Silva, Cristina Ferraz; Moreira, Jane Jesus Silveira; Narain, Narendra; Souza, Roberto Rodrigues

    2011-09-01

    In Brazil, the use of cashew apple (Anacardium occidentale L.) to obtain new products by biotechnological process represents an important alternative to avoid wastage of a large quantity of this fruit, which reaches about 85% of the annual production of 1 million tons. This work focuses on the development of an alcoholic product obtained by the fermentation of cashew apple juice. The inoculation with two different strains of yeast Saccharomyces cerevisiae viz. SCP and SCT, were standardized to a concentration of 10(7 )cells ml(-1). Each inoculum was added to 1,500 ml of cashew must. Fermentation was performed at 28 ± 3°C and aliquots were withdrawn every 24 h to monitor soluble sugar concentrations, pH, and dry matter contents. The volatile compounds in fermented products were analyzed using the gas chromatography/mass spectrometry (GC/MS) system. After 6 days, the fermentation process was completed, cells removed by filtration and centrifugation, and the products were stabilized under refrigeration for a period of 20 days. The stabilized products were stored in glass bottles and pasteurized at 60 ± 5°C/30 min. Both fermented products contained ethanol concentration above 6% (v v(-1)) while methanol was not detected and total acidity was below 90 mEq l(-1), representing a pH of 3.8-3.9. The volatile compounds were characterized by the presence of aldehyde (butyl aldehyde diethyl acetal, 2,4-dimethyl-hepta-2,4-dienal, and 2-methyl-2-pentenal) and ester (ethyl α-methylbutyrate) representing fruity aroma. The strain SCT was found to be better and efficient and this produced 10% more alcohol over that of strain SCP.

  11. Diversity of Saccharomyces cerevisiae strains isolated from Borassus akeassii palm wines from Burkina Faso in comparison to other African beverages.

    Tapsoba, François; Legras, Jean-Luc; Savadogo, Aly; Dequin, Sylvie; Traore, Alfred Sababenedyo

    2015-10-15

    In South-West of Burkina Faso, palm wine is produced by spontaneous fermentation of the sap from a specific palm tree Borassus akeassii and plays an important role in people's lives. Saccharomyces cerevisiae is the main agent of this alcoholic fermentation but little is known about the diversity of the isolates from palm. In this work, 39 Saccharomyces cerevisiae strains were isolated from palm wine samples collected from 14 sites in Burkina Faso, as well as 7 isolates obtained from sorghum beer (Dolo) from 3 distant sites. Their diversity was analyzed at 12 microsatellite loci, and compared to the genotypes obtained for other African yeast populations isolated from Cocoa hulks from Ghana, sorghum beer from Ivory Coast, palm wine from Djibouti Republic, and to our database of strains from miscellaneous origins (bread, beer, wine, sake, oaks…). The ploidy of these strains has been assessed as well by flow cytometry. Our results show that B. akeassii palm wine contains a specific yeast population of diploid strains, different from Dolo produced in the same area and from other palm wine strains from Ivory Coast, Nigeria, or Djibouti Republic. In contrast, Dolo strains appeared as a group of related and mainly tetraploid strains despite being isolated from different countries. Copyright © 2015 Elsevier B.V. All rights reserved.

  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

    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

  13. Excessive by-product formation: A key contributor to low isobutanol yields of engineered Saccharomyces cerevisiae strains.

    Milne, N; Wahl, S A; van Maris, A J A; Pronk, J T; Daran, J M

    2016-12-01

    It is theoretically possible to engineer Saccharomyces cerevisiae strains in which isobutanol is the predominant catabolic product and high-yielding isobutanol-producing strains are already reported by industry. Conversely, isobutanol yields of engineered S. cerevisiae strains reported in the scientific literature typically remain far below 10% of the theoretical maximum. This study explores possible reasons for these suboptimal yields by a mass-balancing approach. A cytosolically located, cofactor-balanced isobutanol pathway, consisting of a mosaic of bacterial enzymes whose in vivo functionality was confirmed by complementation of null mutations in branched-chain amino acid metabolism, was expressed in S. cerevisiae . Product formation by the engineered strain was analysed in shake flasks and bioreactors. In aerobic cultures, the pathway intermediate isobutyraldehyde was oxidized to isobutyrate rather than reduced to isobutanol. Moreover, significant concentrations of the pathway intermediates 2,3-dihydroxyisovalerate and α-ketoisovalerate, as well as diacetyl and acetoin, accumulated extracellularly. While the engineered strain could not grow anaerobically, micro-aerobic cultivation resulted in isobutanol formation at a yield of 0.018±0.003 mol/mol glucose. Simultaneously, 2,3-butanediol was produced at a yield of 0.649±0.067 mol/mol glucose. These results identify massive accumulation of pathway intermediates, as well as overflow metabolites derived from acetolactate, as an important, previously underestimated contributor to the suboptimal yields of 'academic' isobutanol strains. The observed patterns of by-product formation is consistent with the notion that in vivo activity of the iron-sulphur-cluster-requiring enzyme dihydroxyacid dehydratase is a key bottleneck in the present and previously described 'academic' isobutanol-producing yeast strains.

  14. Bakery by-products based feeds borne-Saccharomyces cerevisiae strains with probiotic and antimycotoxin effects plus antibiotic resistance properties for use in animal production.

    Poloni, Valeria; Salvato, Lauranne; Pereyra, Carina; Oliveira, Aguida; Rosa, Carlos; Cavaglieri, Lilia; Keller, Kelly Moura

    2017-09-01

    The aim of this study was to select S. cerevisiae strains able to exert probiotic and antimycotoxin effects plus antibiotics resistance properties for use in animal production. S. cerevisiae LL74 and S. cerevisiae LL83 were isolated from bakery by-products intended for use in animal feed and examined for phenotypic characteristics and nutritional profile. Resistance to antibiotic, tolerance to gastrointestinal conditions, autoaggregation and coaggregation assay, antagonism to animal pathogens and aflatoxin B 1 binding were studied. S. cerevisiae LL74 and S. cerevisiae LL83 showed resistance to all the antibiotics assayed (ampicillin, streptomycin, neomycin, norfloxacin, penicillin G, sulfonamide and trimethoprim). The analysis showed that exposure time to acid pH had a significant impact onto the viable cell counts onto both yeast strains. Presence of bile 0.5% increased significantly the growth of the both yeast strains. Moreover, they were able to tolerate the simulated gastrointestinal conditions assayed. In general, the coaggregation was positive whereas the autoaggregation capacity was not observed. Both strains were able to adsorb AFB 1 . In conclusion, selected S. cerevisiae LL74 and S. cerevisiae LL83 have potential application to be used as a biological method in animal feed as antibiotic therapy replacement in, reducing the adverse effects of AFB 1 and giving probiotic properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Co-consumption of sugars or ethanol and glucose in a Saccharomyces cerevisiae strain deleted in the HXK2 gene.

    Raamsdonk, L M; Diderich, J A; Kuiper, A; van Gaalen, M; Kruckeberg, A L; Berden, J A; Van Dam, K; Kruckberg, A L

    2001-08-01

    In previous studies it was shown that deletion of the HXK2 gene in Saccharomyces cerevisiae yields a strain that hardly produces ethanol and grows almost exclusively oxidatively in the presence of abundant glucose. This paper reports on physiological studies on the hxk2 deletion strain on mixtures of glucose/sucrose, glucose/galactose, glucose/maltose and glucose/ethanol in aerobic batch cultures. The hxk2 deletion strain co-consumed galactose and sucrose, together with glucose. In addition, co-consumption of glucose and ethanol was observed during the early exponential growth phase. In S.cerevisiae, co-consumption of ethanol and glucose (in the presence of abundant glucose) has never been reported before. The specific respiration rate of the hxk2 deletion strain growing on the glucose/ethanol mixture was 900 micromol.min(-1).(g protein)(-1), which is four to five times higher than that of the hxk2 deletion strain growing oxidatively on glucose, three times higher than its parent growing on ethanol (when respiration is fully derepressed) and is almost 10 times higher than its parent growing on glucose (when respiration is repressed). This indicates that the hxk2 deletion strain has a strongly enhanced oxidative capacity when grown on a mixture of glucose and ethanol. Copyright 2001 John Wiley & Sons, Ltd.

  16. The Impact of Single Amino Acids on Growth and Volatile Aroma Production by Saccharomyces cerevisiae Strains

    Samantha Fairbairn

    2017-12-01

    Full Text Available Nitrogen availability and utilization by Saccharomyces cerevisiae significantly influence fermentation kinetics and the production of volatile compounds important for wine aroma. Amino acids are the most important nitrogen source and have been classified based on how well they support growth. This study evaluated the effect of single amino acids on growth kinetics and major volatile production of two phenotypically different commercial wine yeast strains in synthetic grape must. Four growth parameters, lag phase, maximum growth rate, total biomass formation and time to complete fermentation were evaluated. In contrast with previous findings, in fermentative conditions, phenylalanine and valine supported growth well and asparagine supported it poorly. The four parameters showed good correlations for most amino acid treatments, with some notable exceptions. Single amino acid treatments resulted in the predictable production of aromatic compounds, with a linear correlation between amino acid concentration and the concentration of aromatic compounds that are directly derived from these amino acids. With the increased complexity of nitrogen sources, linear correlations were lost and aroma production became unpredictable. However, even in complex medium minor changes in amino acid concentration continued to directly impact the formation of aromatic compounds, suggesting that the relative concentration of individual amino acids remains a predictor of aromatic outputs, independently of the complexity of metabolic interactions between carbon and nitrogen metabolism and between amino acid degradation and utilization pathways.

  17. Biotransformation of soy whey into soy alcoholic beverage by four commercial strains of Saccharomyces cerevisiae.

    Chua, Jian-Yong; Lu, Yuyun; Liu, Shao-Quan

    2017-12-04

    Soy whey is a liquid waste stream generated from tofu and soy protein manufacturing, and is commonly disposed of into the drainage system in food industry. Instead of disposing of soy whey as a waste, it could be used to produce alcoholic beverages. This study investigated the feasibility of converting soy whey into soy alcoholic beverage using four commercial Saccharomyces cerevisiae strains as a zero-waste approach to tackle the soy whey disposal issue. The four Saccharomyces yeasts grew by approximately 2logCFU/mL and produced approximately 7-8% (v/v) of ethanol. Isoflavone glucosides were hydrolyzed and transformed into isoflavone aglycones, increasing the antioxidant capacity. New aroma-active volatiles, especially esters and higher alcohols, were produced and imparted fruity and floral notes to the soy alcoholic beverage. Therefore, alcoholic fermentation would serve as a solution toward zero-waste manufacturing by biotransforming soy whey into a world's first novel functional alcoholic beverage naturally enriched with free isoflavones. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Genome-Wide Transcription Study of Cryptococcus neoformans H99 Clinical Strain versus Environmental Strains.

    Elaheh Movahed

    Full Text Available The infection of Cryptococcus neoformans is acquired through the inhalation of desiccated yeast cells and basidiospores originated from the environment, particularly from bird's droppings and decaying wood. Three environmental strains of C. neoformans originated from bird droppings (H4, S48B and S68B and C. neoformans reference clinical strain (H99 were used for intranasal infection in C57BL/6 mice. We showed that the H99 strain demonstrated higher virulence compared to H4, S48B and S68B strains. To examine if gene expression contributed to the different degree of virulence among these strains, a genome-wide microarray study was performed to inspect the transcriptomic profiles of all four strains. Our results revealed that out of 7,419 genes (22,257 probes examined, 65 genes were significantly up-or down-regulated in H99 versus H4, S48B and S68B strains. The up-regulated genes in H99 strain include Hydroxymethylglutaryl-CoA synthase (MVA1, Mitochondrial matrix factor 1 (MMF1, Bud-site-selection protein 8 (BUD8, High affinity glucose transporter 3 (SNF3 and Rho GTPase-activating protein 2 (RGA2. Pathway annotation using DAVID bioinformatics resource showed that metal ion binding and sugar transmembrane transporter activity pathways were highly expressed in the H99 strain. We suggest that the genes and pathways identified may possibly play crucial roles in the fungal pathogenesis.

  19. Identification of Novel Desiccation-Tolerant S. cerevisiae Strains for Deep Space Biosensors

    Tieze, Sofia Massaro; Santa Maria, Sergio R.; Liddell, Lauren; Bhattacharya, Sharmila

    2017-01-01

    NASA's BioSentinel mission, a secondary payload that will fly on the Space Launch Systems first Exploration Mission (EM-1), utilizes the budding yeast S. cerevisiae to study the biological response to the deep space radiation environment. Yeast samples are desiccated prior to launch to suspend growth and metabolism while the spacecraft travels to its target heliocentric orbit beyond Low Earth Orbit. Each sample is then rehydrated at the desired time points to reactivate the cells. A major risk in this mission is the loss of cell viability that occurs in the recovery period following the desiccation and rehydration process. Cell survival is essential for the detection of the biological response to features in the deep space environment, including ionizing radiation.The aim of this study is to mitigate viable cell loss in future biosensors by identifying mutations and genes that confer tolerance to desiccation stress in rad51, a radiation-sensitive yeast strain. We initiated a screen for desiccation-tolerance after rehydrating cells that were desiccated for three years, and selected various clones exhibiting robust growth. To verify retention of radiation sensitivity in the isolated clonesa crucial feature for a successful biosensorwe exposed them to ionizing radiation. Finally, to elucidate the genetic and molecular bases for observed desiccation-tolerance, we will perform whole-genome sequencing of those rad51 clones that exhibit both robust growth and radiation sensitivity following desiccation. The identification and characterization of desiccation-tolerant strains will allow us to engineer a biological model that will be resilient in face of the challenges of the deep space environment, and will thus ensure the experimental success of future biosensor missions.

  20. Comparative studies on the fermentation performance of autochthonous Saccharomyces cerevisiae strains in Chinese light-fragrant liquor during solid-state or submerged fermentation.

    Kong, Y; Wu, Q; Xu, Y

    2017-04-01

    To explore the metabolic characteristic of autochthonous Saccharomyces cerevisiae strains in Chinese light-fragrant liquor fermentation. Inter-delta amplification analysis was used to differentiate the S. cerevisiae strains at strain level. Twelve biotypes (I-XII) were identified among the 72 S. cerevisiae strains preselected. A comparison was conducted between solid-state fermentation (SSF) and submerged fermentation (SmF) with S. cerevisiae strains had different genotype, with a focus on the production of ethanol and the volatile compounds. The degree of ethanol ranged from 28·0 to 45·2 g l -1 in SmF and from 14·8 to 25·6 g kg -1 in SSF, and SSF was found to be more suitable for the production of ethanol with higher yield coefficient of all the S. cerevisiae strains. The metabolite profiles of each yeast strain showed obvious distinction in the two fermentations. The highest amounts of ethyl acetate in SmF and SSF were found in genotype VII (328·2 μg l -1 ) and genotype V (672 μg kg -1 ), respectively. In addition, the generation of some volatile compounds could be strictly related to the strain used. Compound β-damascenone was only detected in genotypes I, II, X and XII in the two fermentation processes. Furthermore, laboratory scale fermentations were clearly divided into SSF and SmF in hierarchical cluster analysis regardless of the inoculated yeast strains, indicating that the mode of fermentation was more important than the yeast strains inoculated. The autochthonous S. cerevisiae strains in Chinese light-fragrant liquor vary considerably in terms of their volatiles profiles during SSF and SmF. This work facilitates a better understanding of the fermentative mechanism in the SSF process for light-fragrant liquor production. © 2016 The Society for Applied Microbiology.

  1. Inhibitor tolerance of a recombinant flocculating industrial Saccharomyces cerevisiae strain during glucose and xylose co-fermentation

    Yun-Cheng Li

    Full Text Available ABSTRACT Lignocellulose-derived inhibitors have negative effects on the ethanol fermentation capacity of Saccharomyces cerevisiae. In this study, the effects of eight typical inhibitors, including weak acids, furans, and phenols, on glucose and xylose co-fermentation of the recombinant xylose-fermenting flocculating industrial S. cerevisiae strain NAPX37 were evaluated by batch fermentation. Inhibition on glucose fermentation, not that on xylose fermentation, correlated with delayed cell growth. The weak acids and the phenols showed additive effects. The effect of inhibitors on glucose fermentation was as follows (from strongest to weakest: vanillin > phenol > syringaldehyde > 5-HMF > furfural > levulinic acid > acetic acid > formic acid. The effect of inhibitors on xylose fermentation was as follows (from strongest to weakest: phenol > vanillin > syringaldehyde > furfural > 5-HMF > formic acid > levulinic acid > acetic acid. The NAPX37 strain showed substantial tolerance to typical inhibitors and showed good fermentation characteristics, when a medium with inhibitor cocktail or rape straw hydrolysate was used. This research provides important clues for inhibitors tolerance of recombinant industrial xylose-fermenting S. cerevisiae.

  2. Genome-wide RNAi screen reveals the E3 SUMO-protein ligase gene SIZ1 as a novel determinant of furfural tolerance in Saccharomyces cerevisiae

    Xiao, Han; Zhao, Huimin

    2014-01-01

    Background Furfural is a major growth inhibitor in lignocellulosic hydrolysates and improving furfural tolerance of microorganisms is critical for rapid and efficient fermentation of lignocellulosic biomass. In this study, we used the RNAi-Assisted Genome Evolution (RAGE) method to select for furfural resistant mutants of Saccharomyces cerevisiae, and identified a new determinant of furfural tolerance. Results By using a genome-wide RNAi (RNA-interference) screen in S. cerevisiae for genes in...

  3. Menadione stress in Saccharomyces cerevisiae strains deficient in the glutathione transferases.

    Castro, F A V; Herdeiro, R S; Panek, A D; Eleutherio, E C A; Pereira, M D

    2007-02-01

    Using S. cerevisiae as a eukaryotic cell model we have analyzed the involvement of both glutathione transferase isoforms, Gtt1 and Gtt2, in constitutive resistance and adaptive response to menadione, a quinone which can exert its toxicity as redox cycling and/or electrophiles. The detoxification properties, of these enzymes, have also been analyzed by the appearance of S-conjugates in the media. Direct exposure to menadione (20 mM/60 min) showed to be lethal for cells deficient on both Gtt1 and Gtt2 isoforms. However, after pre-treatment with a low menadione concentration, cells deficient in Gtt2 displayed reduced ability to acquire tolerance when compared with the control and the Gtt1 deficient strains. Analyzing the toxic effects of menadione we observed that the gtt2 mutant showed no reduction in lipid peroxidation levels. Moreover, measuring the levels of intracellular oxidation during menadione stress we have shown that the increase of this oxidative stress parameter was due to the capacity menadione possesses in generating reactive oxygen species (ROS) and that both GSH and Gtt2 isoform were required to enhance ROS production. Furthermore, the efflux of the menadione-GSH conjugate, which is related with detoxification of xenobiotic pathways, was not detected in the gtt2 mutant. Taken together, these results suggest that acquisition of tolerance against stress generated by menadione and the process of detoxification through S-conjugates are dependent upon Gtt2 activity. This assessment was corroborated by the increase of GTT2 expression, and not of GTT1, after menadione treatment.

  4. Engineering and two-stage evolution of a lignocellulosic hydrolysate-tolerant Saccharomyces cerevisiae strain for anaerobic fermentation of xylose from AFEX pretreated corn stover.

    Lucas S Parreiras

    Full Text Available The inability of the yeast Saccharomyces cerevisiae to ferment xylose effectively under anaerobic conditions is a major barrier to economical production of lignocellulosic biofuels. Although genetic approaches have enabled engineering of S. cerevisiae to convert xylose efficiently into ethanol in defined lab medium, few strains are able to ferment xylose from lignocellulosic hydrolysates in the absence of oxygen. This limited xylose conversion is believed to result from small molecules generated during biomass pretreatment and hydrolysis, which induce cellular stress and impair metabolism. Here, we describe the development of a xylose-fermenting S. cerevisiae strain with tolerance to a range of pretreated and hydrolyzed lignocellulose, including Ammonia Fiber Expansion (AFEX-pretreated corn stover hydrolysate (ACSH. We genetically engineered a hydrolysate-resistant yeast strain with bacterial xylose isomerase and then applied two separate stages of aerobic and anaerobic directed evolution. The emergent S. cerevisiae strain rapidly converted xylose from lab medium and ACSH to ethanol under strict anaerobic conditions. Metabolomic, genetic and biochemical analyses suggested that a missense mutation in GRE3, which was acquired during the anaerobic evolution, contributed toward improved xylose conversion by reducing intracellular production of xylitol, an inhibitor of xylose isomerase. These results validate our combinatorial approach, which utilized phenotypic strain selection, rational engineering and directed evolution for the generation of a robust S. cerevisiae strain with the ability to ferment xylose anaerobically from ACSH.

  5. Laboratory Evolution of a Biotin-Requiring Saccharomyces cerevisiae Strain for Full Biotin Prototrophy and Identification of Causal Mutations.

    Bracher, Jasmine M; de Hulster, Erik; Koster, Charlotte C; van den Broek, Marcel; Daran, Jean-Marc G; van Maris, Antonius J A; Pronk, Jack T

    2017-08-15

    Biotin prototrophy is a rare, incompletely understood, and industrially relevant characteristic of Saccharomyces cerevisiae strains. The genome of the haploid laboratory strain CEN.PK113-7D contains a full complement of biotin biosynthesis genes, but its growth in biotin-free synthetic medium is extremely slow (specific growth rate [μ] ≈ 0.01 h -1 ). Four independent evolution experiments in repeated batch cultures and accelerostats yielded strains whose growth rates (μ ≤ 0.36 h -1 ) in biotin-free and biotin-supplemented media were similar. Whole-genome resequencing of these evolved strains revealed up to 40-fold amplification of BIO1 , which encodes pimeloyl-coenzyme A (CoA) synthetase. The additional copies of BIO1 were found on different chromosomes, and its amplification coincided with substantial chromosomal rearrangements. A key role of this gene amplification was confirmed by overexpression of BIO1 in strain CEN.PK113-7D, which enabled growth in biotin-free medium (μ = 0.15 h -1 ). Mutations in the membrane transporter genes TPO1 and/or PDR12 were found in several of the evolved strains. Deletion of TPO1 and PDR12 in a BIO1 -overexpressing strain increased its specific growth rate to 0.25 h -1 The effects of null mutations in these genes, which have not been previously associated with biotin metabolism, were nonadditive. This study demonstrates that S. cerevisiae strains that carry the basic genetic information for biotin synthesis can be evolved for full biotin prototrophy and identifies new targets for engineering biotin prototrophy into laboratory and industrial strains of this yeast. IMPORTANCE Although biotin (vitamin H) plays essential roles in all organisms, not all organisms can synthesize this vitamin. Many strains of baker's yeast, an important microorganism in industrial biotechnology, contain at least some of the genes required for biotin synthesis. However, most of these strains cannot synthesize biotin at all or do so at rates that are

  6. Comparing the xylose reductase/xylitol dehydrogenase and xylose isomerase pathways in arabinose and xylose fermenting Saccharomyces cerevisiae strains

    Hahn-Hägerdal Bärbel

    2008-10-01

    Full Text Available Abstract Background Ethanolic fermentation of lignocellulosic biomass is a sustainable option for the production of bioethanol. This process would greatly benefit from recombinant Saccharomyces cerevisiae strains also able to ferment, besides the hexose sugar fraction, the pentose sugars, arabinose and xylose. Different pathways can be introduced in S. cerevisiae to provide arabinose and xylose utilisation. In this study, the bacterial arabinose isomerase pathway was combined with two different xylose utilisation pathways: the xylose reductase/xylitol dehydrogenase and xylose isomerase pathways, respectively, in genetically identical strains. The strains were compared with respect to aerobic growth in arabinose and xylose batch culture and in anaerobic batch fermentation of a mixture of glucose, arabinose and xylose. Results The specific aerobic arabinose growth rate was identical, 0.03 h-1, for the xylose reductase/xylitol dehydrogenase and xylose isomerase strain. The xylose reductase/xylitol dehydrogenase strain displayed higher aerobic growth rate on xylose, 0.14 h-1, and higher specific xylose consumption rate in anaerobic batch fermentation, 0.09 g (g cells-1 h-1 than the xylose isomerase strain, which only reached 0.03 h-1 and 0.02 g (g cells-1h-1, respectively. Whereas the xylose reductase/xylitol dehydrogenase strain produced higher ethanol yield on total sugars, 0.23 g g-1 compared with 0.18 g g-1 for the xylose isomerase strain, the xylose isomerase strain achieved higher ethanol yield on consumed sugars, 0.41 g g-1 compared with 0.32 g g-1 for the xylose reductase/xylitol dehydrogenase strain. Anaerobic fermentation of a mixture of glucose, arabinose and xylose resulted in higher final ethanol concentration, 14.7 g l-1 for the xylose reductase/xylitol dehydrogenase strain compared with 11.8 g l-1 for the xylose isomerase strain, and in higher specific ethanol productivity, 0.024 g (g cells-1 h-1 compared with 0.01 g (g cells-1 h-1

  7. Laboratory Evolution of a Biotin-Requiring Saccharomyces cerevisiae Strain for Full Biotin Prototrophy and Identification of Causal Mutations

    de Hulster, Erik; Koster, Charlotte C.; van den Broek, Marcel; van Maris, Antonius J. A.

    2017-01-01

    ABSTRACT Biotin prototrophy is a rare, incompletely understood, and industrially relevant characteristic of Saccharomyces cerevisiae strains. The genome of the haploid laboratory strain CEN.PK113-7D contains a full complement of biotin biosynthesis genes, but its growth in biotin-free synthetic medium is extremely slow (specific growth rate [μ] ≈ 0.01 h−1). Four independent evolution experiments in repeated batch cultures and accelerostats yielded strains whose growth rates (μ ≤ 0.36 h−1) in biotin-free and biotin-supplemented media were similar. Whole-genome resequencing of these evolved strains revealed up to 40-fold amplification of BIO1, which encodes pimeloyl-coenzyme A (CoA) synthetase. The additional copies of BIO1 were found on different chromosomes, and its amplification coincided with substantial chromosomal rearrangements. A key role of this gene amplification was confirmed by overexpression of BIO1 in strain CEN.PK113-7D, which enabled growth in biotin-free medium (μ = 0.15 h−1). Mutations in the membrane transporter genes TPO1 and/or PDR12 were found in several of the evolved strains. Deletion of TPO1 and PDR12 in a BIO1-overexpressing strain increased its specific growth rate to 0.25 h−1. The effects of null mutations in these genes, which have not been previously associated with biotin metabolism, were nonadditive. This study demonstrates that S. cerevisiae strains that carry the basic genetic information for biotin synthesis can be evolved for full biotin prototrophy and identifies new targets for engineering biotin prototrophy into laboratory and industrial strains of this yeast. IMPORTANCE Although biotin (vitamin H) plays essential roles in all organisms, not all organisms can synthesize this vitamin. Many strains of baker's yeast, an important microorganism in industrial biotechnology, contain at least some of the genes required for biotin synthesis. However, most of these strains cannot synthesize biotin at all or do so at rates

  8. Fermentation of oat and soybean hull hydrolysates into ethanol and xylitol by recombinant industrial strains of Saccharomyces cerevisiae under diverse oxygen environments

    In this study, we evaluated the capacity of recombinant industrial Saccharomyces cerevisiae YRH 396 and YRH 400 strains to ferment sugars from oat hull and soybean hull hydrolysates into ethanol and xylitol. The strains were genetically modified by chromosomal integration of Pichia stipitis XYLI/XYL...

  9. Comparison of SHF and SSF processes from steam-exploded wheat straw for ethanol production by xylose-fermenting and robust glucose-fermenting Saccharomyces cerevisiae strains

    Tomas Pejo, Elia; Oliva, Jose M.; Ballesteros, Mercedes

    2008-01-01

    In this study, bioethanol production from steam-exploded wheat straw using different process configurations was evaluated using two Saccharomyces cerevisiae strains, F12 and Red Star. The strain F12 has been engineerically modified to allow xylose consumption as cereal straw contain considerable ...

  10. Genome Sequences of Industrially Relevant Saccharomyces cerevisiae Strain M3707, Isolated from a Sample of Distillers Yeast and Four Haploid Derivatives

    Brown, Steven D.; Klingeman, Dawn M.; Johnson, Courtney M.; Clum, Alicia; Aerts, Andrea; Salamov, Asaf; Sharma, Aditi; Zane, Matthew; Barry, Kerrie; Grigoriev, Igor V.; Davison, Brian H.; Lynd, Lee R.; Gilna, Paul; Hau, Heidi; Hogsett, David A.; Froehlich, Allan C.

    2013-04-19

    Saccharomyces cerevisiae strain M3707 was isolated from a sample of commercial distillers yeast, and its genome sequence together with the genome sequences for the four derived haploid strains M3836, M3837, M3838, and M3839 has been determined. Yeasts have potential for consolidated bioprocessing (CBP) for biofuel production, and access to these genome sequences will facilitate their development.

  11. Genome Sequence of Saccharomyces cerevisiae Strain Kagoshima No. 2, Used for Brewing the Japanese Distilled Spirit Shōchū.

    Mori, Kazuki; Kadooka, Chihiro; Masuda, Chika; Muto, Ai; Okutsu, Kayu; Yoshizaki, Yumiko; Takamine, Kazunori; Futagami, Taiki; Tamaki, Hisanori

    2017-10-12

    Here, we report a draft genome sequence of Saccharomyces cerevisiae strain Kagoshima no. 2, which is used for brewing shōchū, a traditional distilled spirit in Japan. The genome data will facilitate an understanding of the evolutional traits and genetic background related to the characteristic features of strain Kagoshima no. 2. Copyright © 2017 Mori et al.

  12. Evaluating the probiotic and therapeutic potentials of Saccharomyces cerevisiae strain (OBS2) isolated from fermented nectar of toddy palm.

    Srinivas, Banoth; Rani, Ganapathiwar Swarupa; Kumar, Bhukya Kiran; Chandrasekhar, Banoth; Krishna, Kommalapati Vamsi; Devi, Tangutur Anjana; Bhima, Bhukya

    2017-12-01

    The purpose of this study is to evaluate the probiotic characteristics of 15 yeast strains isolated from nectar of toddy palm. Initially, the collected samples were inoculated on yeast extract peptone dextrose agar plates and the colonies so obtained were culturally and morphologically characterized. Commercial probiotic yeast, Saccharomyces boulardii served as the control in these experiments. Of the 15 yeast strains, the isolates that were resistant to antibiotics and worked synergistically with other cultures were considered for further evaluation. Selected isolates were evaluated in vitro for tolerance to simulated gastrointestinal conditions such as temperature, pH, bile and gastric juice. Further the yeast isolates were evaluated for their pathogenicity and adherence to intestinal epithelial cells. The 2 yeast isolates with efficient probiotic properties were finally characterized by sequencing their 5.8 S rRNA and partial sequences of internal transcribed spacer 1 and 2. The sequences were BLAST searched in the National Center for Biotechnology Information, nucleic acid database for sequence similarity of organisms and phylogenetic evolutionary analysis was carried out. Based on maximum similarity of basic local alignment search tool results, organisms were characterized as Pichia kudriavzevii OBS1 (100%) and Saccharomyces cerevisiae OBS2 (96%) and sequences were finally deposited in the GenBank data library. Among these two isolates, S. cerevisiae OBS2 displayed slight/moderate antioxidant and anticancer property. Hence, strain OBS2 can be utilized and explored as a potential probiotic for therapeutic applications.

  13. FLO11 gene length and transcriptional level affect biofilm-forming ability of wild flor strains of Saccharomyces cerevisiae.

    Zara, Giacomo; Zara, Severino; Pinna, Claudia; Marceddu, Salvatore; Budroni, Marilena

    2009-12-01

    In Saccharomyces cerevisiae, FLO11 encodes an adhesin that is associated with different phenotypes, such as adherence to solid surfaces, hydrophobicity, mat and air-liquid biofilm formation. In the present study, we analysed FLO11 allelic polymorphisms and FLO11-associated phenotypes of 20 flor strains. We identified 13 alleles of different lengths, varying from 3.0 to 6.1 kb, thus demonstrating that FLO11 is highly polymorphic. Two alleles of 3.1 and 5.0 kb were cloned into strain BY4742 to compare the FLO11-associated phenotypes in the same genetic background. We show that there is a significant correlation between biofilm-forming ability and FLO11 length both in different and in the same genetic backgrounds. Moreover, we propose a multiple regression model that allows prediction of air-liquid biofilm-forming ability on the basis of transcription levels and lengths of FLO11 alleles in a population of S. cerevisiae flor strains. Considering that transcriptional differences are only partially explained by the differences in the promoter sequences, our results are consistent with the hypothesis that FLO11 transcription levels are strongly influenced by genetic background and affect biofilm-forming ability.

  14. An efficient xylose-fermenting recombinant Saccharomyces cerevisiae strain obtained through adaptive evolution and its global transcription profile

    Shen, Yu; Chen, Xiao; Peng, Bingyin; Chen, Liyuan; Hou, Jin; Bao, Xiaoming [Shandong Univ., Jinan (China). State Key Lab. of Microbial Technology

    2012-11-15

    Factors related to ethanol production from xylose in engineered Saccharomyces cerevisiae that contain an exogenous initial metabolic pathway are still to be elucidated. In the present study, a strain that expresses the xylose isomerase gene of Piromyces sp. Pi-xylA and overexpresses XKS1, RPE1, RKI1, TAL1, and TKL1, with deleted GRE3 and COX4 genes was constructed. The xylose utilization capacity of the respiratory deficiency strain was poor but improved via adaptive evolution in xylose. The {mu}{sub max} of the evolved strain in 20 gl{sup -1} xylose is 0.11 {+-} 0.00 h{sup -1}, and the evolved strain consumed 17.83 gl{sup -1} xylose within 72 h, with an ethanol yield of 0.43 gg{sup -1} total consumed sugars during glucose-xylose cofermentation. Global transcriptional changes and effect of several specific genes were studied. The result revealed that the increased xylose isomerase activity, the upregulation of enzymes involved in glycolysis and glutamate synthesis, and the downregulation of trehalose and glycogen synthesis, may have contributed to the improved xylose utilization of the strain. Furthermore, the deletion of PHO13 decreased the xylose growth in the respiration deficiency strain although deleting PHO13 can improve the xylose metabolism in other strains. (orig.)

  15. The effect of hexose ratios on metabolite production in Saccharomyces cerevisiae strains obtained from the spontaneous fermentation of mezcal.

    Oliva Hernández, Amanda A; Taillandier, Patricia; Reséndez Pérez, Diana; Narváez Zapata, José A; Larralde Corona, Claudia Patricia

    2013-04-01

    Mezcal from Tamaulipas (México) is produced by spontaneous alcoholic fermentation using Agave spp. musts, which are rich in fructose. In this study eight Saccharomyces cerevisiae isolates obtained at the final stage of fermentation from a traditional mezcal winery were analysed in three semi-synthetic media. Medium M1 had a sugar content of 100 g l(-1) and a glucose/fructose (G/F) of 9:1. Medium M2 had a sugar content of 100 g l(-1) and a G/F of 1:9. Medium M3 had a sugar content of 200 g l(-1) and a G/F of 1:1. In the three types of media tested, the highest ethanol yield was obtained from the glucophilic strain LCBG-3Y5, while strain LCBG-3Y8 was highly resistant to ethanol and the most fructophilic of the mezcal strains. Strain LCBG-3Y5 produced more glycerol (4.4 g l(-1)) and acetic acid (1 g l(-1)) in M2 than in M1 (1.7 and 0.5 g l(-1), respectively), and the ethanol yields were higher for all strains in M1 except for LCBG-3Y5, -3Y8 and the Fermichamp strain. In medium M3, only the Fermichamp strain was able to fully consume the 100 g of fructose l(-1) but left a residual 32 g of glucose l(-1). Regarding the hexose transporters, a high number of amino acid polymorphisms were found in the Hxt1p sequences. Strain LCBG-3Y8 exhibited eight unique amino acid changes, followed by the Fermichamp strain with three changes. In Hxt3p, we observed nine amino acid polymorphisms unique for the Fermichamp strain and five unique changes for the mezcal strains.

  16. Saccharomyces cerevisiae UE-ME3 is a good strain for isoproturon biorremediation?

    Candeias, M; Alves-Pereira, I; Ferreira, R

    2010-01-01

    Isoproturon, an herbicide of pre- and pos-emergence of Autumn-Winter crops, persists occasionally in soil, groundwater and biological systems at levels above those established by European Directives. Saccharomyces cerevisiae UE-ME3 exposed in stationary phase to 50 and 100 mM isoproturon exhibit growth rates higher than control or exposed cells to 5 and 25 mM of this phenylurea. However, in S.cerevisiae UE-ME3 grown in the presence of 5 mM isoproturon, were observed a decrease of ...

  17. High hydrostatic pressure activates gene expression that leads to ethanol production enhancement in a Saccharomyces cerevisiae distillery strain

    Bravim, Fernanda; Lippman, Soyeon I.; da Silva, Lucas F.; Souza, Diego T.; Fernandes, A. Alberto R.; Masuda, Claudio A.; Broach, James R.

    2016-01-01

    High hydrostatic pressure (HHP) is a stress that exerts broad effects on microorganisms with characteristics similar to those of common environmental stresses. In this study, we aimed to identify genetic mechanisms that can enhance alcoholic fermentation of wild Saccharomyces cerevisiae isolated from Brazilian spirit fermentation vats. Accordingly, we performed a time course microarray analysis on a S. cerevisiae strain submitted to mild sublethal pressure treatment of 50 MPa for 30 min at room temperature, followed by incubation for 5, 10 and 15 min without pressure treatment. The obtained transcriptional profiles demonstrate the importance of post-pressurisation period on the activation of several genes related to cell recovery and stress tolerance. Based on these results, we over-expressed genes strongly induced by HHP in the same wild yeast strain and identified genes, particularly SYM1, whose over-expression results in enhanced ethanol production and stress tolerance upon fermentation. The present study validates the use of HHP as a biotechnological tool for the fermentative industries. PMID:22915193

  18. Improved ethanol production at high temperature by consolidated bioprocessing using Saccharomyces cerevisiae strain engineered with artificial zinc finger protein.

    Khatun, M Mahfuza; Yu, Xinshui; Kondo, Akihiko; Bai, Fengwu; Zhao, Xinqing

    2017-12-01

    In this work, the consolidated bioprocessing (CBP) yeast Saccharomyces cerevisiae MNII/cocδBEC3 was transformed by an artificial zinc finger protein (AZFP) library to improve its thermal tolerance, and the strain MNII-AZFP with superior growth at 42°C was selected. Improved degradation of acid swollen cellulose by 45.9% led to an increase in ethanol production, when compared to the control strain. Moreover, the fermentation of Jerusalem artichoke stalk (JAS) by MNII-AZFP was shortened by 12h at 42°C with a concomitant improvement in ethanol production. Comparative transcriptomics analysis suggested that the AZFP in the mutant exerted beneficial effect by modulating the expression of multiple functional genes. These results provide a feasible strategy for efficient ethanol production from JAS and other cellulosic biomass through CBP based-fermentation at elevated temperatures. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Differing effects of 2 active dried yeast (Saccharomyces cerevisiae) strains on ruminal acidosis and methane production in nonlactating dairy cows.

    Chung, Y-H; Walker, N D; McGinn, S M; Beauchemin, K A

    2011-05-01

    Fifteen ruminally cannulated, nonlactating Holstein cows were used to measure the effects of 2 strains of Saccharomyces cerevisiae, fed as active dried yeasts, on ruminal pH and fermentation and enteric methane (CH(4)) emissions. Nonlactating cows were blocked by total duration (h) that their ruminal pH was below 5.8 during a 6-d pre-experimental period. Within each block, cows were randomly assigned to control (no yeast), yeast strain 1 (Levucell SC), or yeast strain 2 (a novel strain selected for enhanced in vitro fiber degradation), with both strains (Lallemand Animal Nutrition, Montréal, QC, Canada) providing 1 × 10(10) cfu/head per day. Cows were fed once daily a total mixed ration consisting of a 50:50 forage to concentrate ratio (dry matter basis). The yeast strains were dosed via the rumen cannula daily at the time of feeding. During the 35-d experiment, ruminal pH was measured continuously for 7 d (d 22 to 28) by using an indwelling system, and CH(4) gas was measured for 4 d (d 32 to 35) using the sulfur hexafluoride tracer gas technique (with halters and yokes). Rumen contents were sampled on 2 d (d 22 and 26) at 0, 3, and 6h after feeding. Dry matter intake, body weight, and apparent total-tract digestibility of nutrients were not affected by yeast feeding. Strain 2 decreased the average daily minimum (5.35 vs. 5.65 or 5.66), mean (5.98 vs. 6.24 or 6.34), and maximum ruminal pH (6.71 vs. 6.86 or 6.86), and prolonged the time that ruminal pH was below 5.8 (7.5 vs. 3.3 or 1.0 h/d) compared with the control or strain 1, respectively. The molar percentage of acetate was lower and that of propionate was greater in the ruminal fluid of cows receiving strain 2 compared with cows receiving no yeast or strain 1. Enteric CH(4) production adjusted for intake of dry matter or gross energy, however, did not differ between either yeast strain compared with the control but it tended to be reduced by 10% when strain 2 was compared with strain 1. The study shows that

  20. Gene expression cross-profiling in genetically modified industrial Saccharomyces cerevisiae strains during high-temperature ethanol production from xylose.

    Ismail, Ku Syahidah Ku; Sakamoto, Takatoshi; Hatanaka, Haruyo; Hasunuma, Tomohisa; Kondo, Akihiko

    2013-01-10

    Production of ethanol from xylose at high temperature would be an economical approach since it reduces risk of contamination and allows both the saccharification and fermentation steps in SSF to be running at elevated temperature. Eight recombinant xylose-utilizing Saccharomyces cerevisiae strains developed from industrial strains were constructed and subjected to high-temperature fermentation at 38 °C. The best performing strain was sun049T, which produced up to 15.2 g/L ethanol (63% of the theoretical production), followed by sun048T and sun588T, both with 14.1 g/L ethanol produced. Via transcriptomic analysis, expression profiling of the top three best ethanol producing strains compared to a negative control strain, sun473T, led to the discovery of genes in common that were regulated in the same direction. Identification of the 20 most highly up-regulated and the 20 most highly down-regulated genes indicated that the cells regulate their central metabolism and maintain the integrity of the cell walls in response to high temperature. We also speculate that cross-protection in the cells occurs, allowing them to maintain ethanol production at higher concentration under heat stress than the negative controls. This report provides further transcriptomics information in the interest of producing a robust microorganism for high-temperature ethanol production utilizing xylose. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Genome-wide map of Apn1 binding sites under oxidative stress in Saccharomyces cerevisiae.

    Morris, Lydia P; Conley, Andrew B; Degtyareva, Natalya; Jordan, I King; Doetsch, Paul W

    2017-11-01

    The DNA is cells is continuously exposed to reactive oxygen species resulting in toxic and mutagenic DNA damage. Although the repair of oxidative DNA damage occurs primarily through the base excision repair (BER) pathway, the nucleotide excision repair (NER) pathway processes some of the same lesions. In addition, damage tolerance mechanisms, such as recombination and translesion synthesis, enable cells to tolerate oxidative DNA damage, especially when BER and NER capacities are exceeded. Thus, disruption of BER alone or disruption of BER and NER in Saccharomyces cerevisiae leads to increased mutations as well as large-scale genomic rearrangements. Previous studies demonstrated that a particular region of chromosome II is susceptible to chronic oxidative stress-induced chromosomal rearrangements, suggesting the existence of DNA damage and/or DNA repair hotspots. Here we investigated the relationship between oxidative damage and genomic instability utilizing chromatin immunoprecipitation combined with DNA microarray technology to profile DNA repair sites along yeast chromosomes under different oxidative stress conditions. We targeted the major yeast AP endonuclease Apn1 as a representative BER protein. Our results indicate that Apn1 target sequences are enriched for cytosine and guanine nucleotides. We predict that BER protects these sites in the genome because guanines and cytosines are thought to be especially susceptible to oxidative attack, thereby preventing large-scale genome destabilization from chronic accumulation of DNA damage. Information from our studies should provide insight into how regional deployment of oxidative DNA damage management systems along chromosomes protects against large-scale rearrangements. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

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

    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.

  3. Yield improvement of heterologous peptides expressed in yps1-disrupted Saccharomyces cerevisiae strains.

    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.

  4. Relationship between solute permeability and osmotic remediability in a galactose-negative strain of Saccharomyces cerevisiae.

    Bassel, J; Douglas, H C

    1970-11-01

    An osmotic remedial allele, gal 7-1, in the galactose pathway of Saccharomyces cerevisiae responds to either penetrating (ethylene glycol and diethylene glycol) or nonpenetrating (KCl, NaCl, and sorbitol) solutes in the growth medium. Extracts from cells grown under restrictive conditions gave no increase in enzyme activity (gal-1-phosphate, uridylyl transferase) when exposed to the penetrating solutes; thus protein synthesis or possibly polymer assembly is proposed as the critical step remedied by the addition of the solutes.

  5. Improving the productivity of S-adenosyl-l-methionine by metabolic engineering in an industrial Saccharomyces cerevisiae strain.

    Zhao, Weijun; Hang, Baojian; Zhu, Xiangcheng; Wang, Ri; Shen, Minjie; Huang, Lei; Xu, Zhinan

    2016-10-20

    S-Adenosyl-l-methionine (SAM) is an important metabolite having prominent roles in treating various diseases. In order to improve the production of SAM, the regulation of three metabolic pathways involved in SAM biosynthesis were investigated in an industrial yeast strain ZJU001. GLC3 encoded glycogen-branching enzyme (GBE), SPE2 encoded SAM decarboxylase, as well as ERG4 and ERG6 encoded key enzymes in ergosterol biosynthesis, were knocked out in ZJU001 accordingly. The results indicated that blocking of either glycogen pathway or SAM decarboxylation pathway could improve the SAM accumulation significantly in ZJU001, while single disruption of either ERG4 or ERG6 gene had no obvious effect on SAM production. Moreover, the double mutant ZJU001-GS with deletion of both GLC3 and SPE2 genes was also constructed, which showed further improvement of SAM accumulation. Finally, SAM2 was overexpressed in ZJU001-GS to give the best SAM-producing recombinant strain ZJU001-GS-SAM2, in which 12.47g/L SAM was produced by following our developed pseudo-exponential fed-batch cultivation strategy, about 81.0% increase comparing to its parent strain ZJU001. The present work laid a solid base for large-scale SAM production with the industrial Saccharomyces cerevisiae strain. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Identification by phenotypic and genetic approaches of an indigenous Saccharomyces cerevisiae wine strain with high desiccation tolerance.

    Zambuto, Marianna; Romaniello, Rossana; Guaragnella, Nicoletta; Romano, Patrizia; Votta, Sonia; Capece, Angela

    2017-10-01

    During active dry yeast (ADY) production process, cells are exposed to multiple stresses, such as thermal, oxidative and hyperosmotic shock. Previously, by analysing cells in exponential growth phase, we selected an indigenous Saccharomyces cerevisiae wine strain, namely CD-6Sc, for its higher tolerance to desiccation and higher expression of specific desiccation stress-related genes in comparison to other yeast strains. In this study, we performed a desiccation treatment on stationary phase cells by comparing the efficacy of two different methods: a 'laboratory dry test' on a small scale (mild stress) and a treatment by spray-drying (severe stress), one of the most appropriate preservation method for yeasts and other micro-organisms. The expression of selected desiccation-related genes has been also assessed in order to validate predictive markers for desiccation tolerance. Our data demonstrate that the 'mild' and the 'severe' desiccation treatments give similar results in terms of cell recovery, but the choice of marker genes strictly depends on the growth phase in which cells undergo desiccation. The indigenous CD-6Sc was ultimately identified as a high dehydration stress-tolerant indigenous strain suitable for ADY production. This study highlights the exploitation of natural yeast biodiversity as a source of hidden technological features and as an alternative approach to strain improvement by genetic modifications. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  7. Genetic engineering of industrial Saccharomyces cerevisiae strains using a selection/counter-selection approach.

    Kutyna, Dariusz R; Cordente, Antonio G; Varela, Cristian

    2014-01-01

    Gene modification of laboratory yeast strains is currently a very straightforward task thanks to the availability of the entire yeast genome sequence and the high frequency with which yeast can incorporate exogenous DNA into its genome. Unfortunately, laboratory strains do not perform well in industrial settings, indicating the need for strategies to modify industrial strains to enable strain development for industrial applications. Here we describe approaches we have used to genetically modify industrial strains used in winemaking.

  8. Evolutionary engineering of a glycerol-3-phosphate dehydrogenase-negative, acetate-reducing Saccharomyces cerevisiae strain enables anaerobic growth at high glucose concentrations

    Guadalupe-Medina, Víctor; Metz, Benjamin; Oud, Bart; van Der Graaf, Charlotte M; Mans, Robert; Pronk, Jack T; van Maris, Antonius J A

    2014-01-01

    Glycerol production by Saccharomyces cerevisiae, which is required for redox-cofactor balancing in anaerobic cultures, causes yield reduction in industrial bioethanol production. Recently, glycerol formation in anaerobic S. cerevisiae cultures was eliminated by expressing Escherichia coli (acetylating) acetaldehyde dehydrogenase (encoded by mhpF) and simultaneously deleting the GPD1 and GPD2 genes encoding glycerol-3-phosphate dehydrogenase, thus coupling NADH reoxidation to reduction of acetate to ethanol. Gpd– strains are, however, sensitive to high sugar concentrations, which complicates industrial implementation of this metabolic engineering concept. In this study, laboratory evolution was used to improve osmotolerance of a Gpd– mhpF-expressing S. cerevisiae strain. Serial batch cultivation at increasing osmotic pressure enabled isolation of an evolved strain that grew anaerobically at 1 M glucose, at a specific growth rate of 0.12 h−1. The evolved strain produced glycerol at low concentrations (0.64 ± 0.33 g l−1). However, these glycerol concentrations were below 10% of those observed with a Gpd+ reference strain. Consequently, the ethanol yield on sugar increased from 79% of the theoretical maximum in the reference strain to 92% for the evolved strains. Genetic analysis indicated that osmotolerance under aerobic conditions required a single dominant chromosomal mutation, and one further mutation in the plasmid-borne mhpF gene for anaerobic growth. PMID:24004455

  9. Effect of 905 MHz microwave radiation on colony growth of the yeast Saccharomyces cerevisiae strains FF18733, FF1481 and D7

    Vrhovac, Ivana; Hrascan, Reno; Franekic, Jasna

    2010-01-01

    The aim of this study was to evaluate the effect of weak radiofrequency microwave (RF/MW) radiation emitted by mobile phones on colony growth of the yeast Saccharomyces cerevisiae. S. cerevisiae strains FF18733 (wild-type), FF1481 (rad1 mutant) and D7 (commonly used to detect reciprocal and nonreciprocal mitotic recombinations) were exposed to a 905 MHz electromagnetic field that closely matched the Global System for Mobile Communication (GSM) pulse modulation signals for mobile phones at a specific absorption rate (SAR) of 0.12 W/kg. Following 15-, 30- and 60-minutes exposure to RF/MW radiation, strain FF18733 did not show statistically significant changes in colony growth compared to the control sample. The irradiated strains FF1481 and D7 demonstrated statistically significant reduction of colony growth compared to non-irradiated strains after all exposure times. Furthermore, strain FF1481 was more sensitive to RF/MW radiation than strain D7. The findings indicate that pulsed RF/MW radiation at a low SAR level can affect the rate of colony growth of different S. cerevisiae strains

  10. Effects of feedstock and co-culture of Lactobacillus fermentum and wild Saccharomyces cerevisiae strain during fuel ethanol fermentation by the industrial yeast strain PE-2.

    Reis, Vanda R; Bassi, Ana Paula G; Cerri, Bianca C; Almeida, Amanda R; Carvalho, Isis G B; Bastos, Reinaldo G; Ceccato-Antonini, Sandra R

    2018-02-16

    Even though contamination by bacteria and wild yeasts are frequently observed during fuel ethanol fermentation, our knowledge regarding the effects of both contaminants together is very limited, especially considering that the must composition can vary from exclusively sugarcane juice to a mixture of molasses and juice, affecting the microbial development. Here we studied the effects of the feedstock (sugarcane juice and molasses) and the co-culture of Lactobacillus fermentum and a wild Saccharomyces cerevisiae strain (rough colony and pseudohyphae) in single and multiple-batch fermentation trials with an industrial strain of S. cerevisiae (PE-2) as starter yeast. The results indicate that in multiple-cycle batch system, the feedstock had a minor impact on the fermentation than in single-cycle batch system, however the rough yeast contamination was more harmful than the bacterial contamination in multiple-cycle batch fermentation. The inoculation of both contaminants did not potentiate the detrimental effect in any substrate. The residual sugar concentration in the fermented broth had a higher concentration of fructose than glucose for all fermentations, but in the presence of the rough yeast, the discrepancy between fructose and glucose concentrations were markedly higher, especially in molasses. The biggest problem associated with incomplete fermentation seemed to be the lower consumption rate of sugar and the reduced fructose preference of the rough yeast rather than the lower invertase activity. Lower ethanol production, acetate production and higher residual sugar concentration are characteristics strongly associated with the rough yeast strain and they were not potentiated with the inoculation of L. fermentum.

  11. Saccharomyces cerevisiae CCMI 885 secretes peptides that inhibit the growth of some non-Saccharomyces wine-related strains

    Albergaria, Helena; Francisco, Diana; Gori, Klaus

    2010-01-01

    of mixed supernatants towards H. guilliermondii was inactivated by protease treatments, thus revealing the proteinaceous nature of the toxic compounds. Analysis of the protein pattern of mixed supernatants on Tricine SDS-PAGE showed that this S. cerevisiae strain secretes peptides (

  12. Growth of catalase A and catalase T deficient mutant strains of Saccharomyces cerevisiae on ethanol and oleic acid : Growth profiles and catalase activities in relation to microbody proliferation

    Klei, Ida J. van der; Rytka, Joanna; Kunau, Wolf H.; Veenhuis, Marten

    The parental strain (A+T+) of Saccharomyces cerevisiae and mutants, deficient in catalase T (A+T-), catalase A (A-T+) or both catalases (A-T-), grew on ethanol and oleic acid with comparable doubling times. Specific activities of catalase were low in glucose- and ethanol-grown cells. In the two

  13. FLO11 expression and lipid biosynthesis are required for air-liquid biofilm formation in a Saccharomyces cerevisiae flor strain.

    Zara, Giacomo; Goffrini, Paola; Lodi, Tiziana; Zara, Severino; Mannazzu, Ilaria; Budroni, Marilena

    2012-11-01

    Air-liquid biofilm formation is largely dependent on Flo11p and seems related to cell lipid content and composition. Here, it is shown that in the presence of cerulenin, a known inhibitor of the fatty acid synthase complex, biofilm formation is inhibited together with FLO11 transcription in a flor strain of Saccharomyces cerevisiae, while the administration of saturated fatty acids to cerulenin-containing medium restores biofilm formation and FLO11 transcription. It is also shown that, in biofilm cells, the FLO11 transcription is accompanied by the transcription of ACC1, ACS1 and INO1 key genes in lipid biosynthesis and that biofilm formation is affected by the lack of inositol in flor medium. These results are compatible with the hypothesis that the air-liquid biofilm formation depends on FLO11 transcription levels as well as on fatty acids biosynthesis. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  14. Mitotic chromosome loss in a radiation-sensitive strain of the yeast Saccharomyces cerevisiae

    Mortimer, R.K.; Contopoulou, R.; Schild, D.

    1981-01-01

    Cells of Saccharomyces cerevisiae with mutations in the RAD52 gene have previously been shown to be defective in meiotic and mitotic recombination, in sporulation, and in repair of radiation-induced damage to DNA. In this study we show that diploid cells homozygous for rad52 lose chromosomes at high frequencies and that these frequencies of loss can be increased dramatically by exposure of these cells to x-rays. Genetic analyses of survivors of x-ray treatment demonstrate that chromosome loss events result in the conversion of diploid cells to cells with near haploid chromosome numbers

  15. Growth of catalase A and catalase T deficient mutant strains of Saccharomyces cerevisiae on ethanol and oleic acid: Growth profiles and catalase activities in relation to microbody proliferation

    Klei, Ida J. van der; Rytka, Joanna; Kunau, Wolf H.; Veenhuis, Marten

    1990-01-01

    The parental strain (A+T+) of Saccharomyces cerevisiae and mutants, deficient in catalase T (A+T-), catalase A (A-T+) or both catalases (A-T-), grew on ethanol and oleic acid with comparable doubling times. Specific activities of catalase were low in glucose- and ethanol-grown cells. In the two oleic acid-grown A+-strains (A+T+ and A+T-) high catalase activities were found; catalase activity invariably remained low in the A-T+ strain and was never detected in the A-T- strain. The levels of β-...

  16. Influence of Saccharomyces cerevisiae Strains on General Composition and Sensorial Properties of White Wines Made from Vitis vinifera cv. Albariño

    Mar Vilanova

    2005-01-01

    Full Text Available Yeast strains contribute to the oenological and sensorial characteristics of the wines they produce. The present study was performed to determine the influence of Saccharomyces cerevisiae strains on the composition and sensorial properties of Albariño wine. The must obtained from Albariño grapes was inoculated with 12 different yeast strains isolated from a single winery in Galicia, Spain. Chemical and sensorial analyses were performed on the final wines, which differed depending on the yeast strain used.

  17. Yeast Autolysis in Sparkling Wine Aging: Use of Killer and Sensitive Saccharomyces cerevisiae Strains in Co-Culture.

    Lombardi, Silvia Jane; De Leonardis, Antonella; Lustrato, Giuseppe; Testa, Bruno; Iorizzo, Massimo

    2015-01-01

    Sparkling wines produced by traditional method owe their characteristics to secondary fermentation and maturation that occur during a slow ageing in bottles. Yeast autolysis plays an important role during the sparkling wine aging. Using a combination of killer and sensitive yeasts is possible to accelerate yeast autolysis and reduce maturing time. killer and sensitive Saccharomyces cerevisiae strains, separately and in co-cultures, were inoculated in base wine and bottled on pilot-plant scale. Commercial Saccaromyces bayanus strain was also investigated. Protein free amino acid and polysaccharides contents and sensory analysis were determined on the wine samples at 3, 6 and 9 months of aging. Yeast autolysis that occurs during the production of sparkling wines, obtained with co-cultures of killer and sensitive strains, has influenced free amino acids, total protein and polysaccharides content after 3 months aging time: sparkling wines, produced without the use of these yeasts, have reached the same results only after 9 months aging time. These results demonstrate that killer and sensitive yeasts in co-culture can accelerate the onset of autolysis in enological conditions, and has a positive effect on the quality of the aroma and flavor of sparkling wine. This paper offers an interesting biotechnological method to reduce production time of sparkling wine with economical benefits for the producers. We revised all patents relating to sparkling wine considering only those of interest for our study.

  18. Robust cellulosic ethanol production from SPORL-pretreated lodgepole pine using an adapted strain Saccharomyces cerevisiae without detoxification.

    Tian, S; Luo, X L; Yang, X S; Zhu, J Y

    2010-11-01

    This study reports an ethanol yield of 270L/ton wood from lodgepole pine pretreated with sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) using an adapted strain, Saccharomyces cerevisiae Y5, without detoxification. The enzymatic hydrolysate produced from pretreated cellulosic solids substrate was combined with pretreatment hydrolysate before fermentation. Detoxification of the pretreatment hydrolysate using overliming or XAD-4 resin before being combined with enzymatic hydrolysate improved ethanol productivity in the first 4h of fermentation and overall fermentation efficiency. However, detoxification did not improve final ethanol yield because of sugar losses. The Y5 strain showed excellent ethanol productivities of 2.0 and 0.8g/L/h averaged over a period of 4 and 24h, respectively, in the undetoxified run. The furan metabolization rates of the Y5 strain were significantly higher for the undetoxified run than those for the detoxidfied runs, suggesting it can tolerate even higher furan concentrations than those studied. Preliminary mass and energy balances were conducted. SPORL produced an excellent monomeric sugar recovery value of about 85% theoretical and a net energy output of 4.05GJ/ton wood with an ethanol energy production efficiency of 178% before distillation.

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

    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 ( TD 12), simultaneous and sequential inoculation with two Saccharomyces strains (indigenous icewine yeast SC 45 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 SC 45/ TD 12 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/ TD 12 generated more C 6 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

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

    Bo-Qin Zhang

    2018-04-01

    Full Text Available 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

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

    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

  2. Genome-wide high-resolution mapping of UV-induced mitotic recombination events in Saccharomyces cerevisiae.

    Yi Yin

    2013-10-01

    Full Text Available In the yeast Saccharomyces cerevisiae and most other eukaryotes, mitotic recombination is important for the repair of double-stranded DNA breaks (DSBs. Mitotic recombination between homologous chromosomes can result in loss of heterozygosity (LOH. In this study, LOH events induced by ultraviolet (UV light are mapped throughout the genome to a resolution of about 1 kb using single-nucleotide polymorphism (SNP microarrays. UV doses that have little effect on the viability of diploid cells stimulate crossovers more than 1000-fold in wild-type cells. In addition, UV stimulates recombination in G1-synchronized cells about 10-fold more efficiently than in G2-synchronized cells. Importantly, at high doses of UV, most conversion events reflect the repair of two sister chromatids that are broken at approximately the same position whereas at low doses, most conversion events reflect the repair of a single broken chromatid. Genome-wide mapping of about 380 unselected crossovers, break-induced replication (BIR events, and gene conversions shows that UV-induced recombination events occur throughout the genome without pronounced hotspots, although the ribosomal RNA gene cluster has a significantly lower frequency of crossovers.

  3. GEMMER: GEnome-wide tool for Multi-scale Modeling data Extraction and Representation for Saccharomyces cerevisiae.

    Mondeel, Thierry D G A; Crémazy, Frédéric; Barberis, Matteo

    2018-02-01

    Multi-scale modeling of biological systems requires integration of various information about genes and proteins that are connected together in networks. Spatial, temporal and functional information is available; however, it is still a challenge to retrieve and explore this knowledge in an integrated, quick and user-friendly manner. We present GEMMER (GEnome-wide tool for Multi-scale Modelling data Extraction and Representation), a web-based data-integration tool that facilitates high quality visualization of physical, regulatory and genetic interactions between proteins/genes in Saccharomyces cerevisiae. GEMMER creates network visualizations that integrate information on function, temporal expression, localization and abundance from various existing databases. GEMMER supports modeling efforts by effortlessly gathering this information and providing convenient export options for images and their underlying data. GEMMER is freely available at http://gemmer.barberislab.com. Source code, written in Python, JavaScript library D3js, PHP and JSON, is freely available at https://github.com/barberislab/GEMMER. M.Barberis@uva.nl. Supplementary data are available at Bioinformatics online. © The Author(s) 2018. Published by Oxford University Press.

  4. INHIBITION OF THE GROWTH OF TOLERANT YEAST Saccharomyces cerevisiae STRAIN I136 BY A MIXTURE OF SYNTHETIC INHIBITORS

    Eny Ida Riyanti

    2017-09-01

    Full Text Available Biomass from lignocellulosic wastes is a potential source for biobased products.  However, one of the constraints in utilization of biomass hydrolysate is the presence of inhibitors. Therefore, the use of inhibitor-tolerant microorganisms in the fermentation is required. The study aimed to investigate the effect of a mixture of inhibitors on the growth of Saccharomyces cerevisiae strain I136 grown in medium containing synthetic inhibitors (acetic acid, formic acid, furfural, 5-hydroxymethyl furfural/5-HMF, and levulinic acid in four different concentrations with a mixture of carbon sources, glucose  (50 g.l-1 and xylose (50 g.l-1 at 30oC. The parameters related to growth and fermentation products were observed. Results showed that the strain was able to grow in media containing natural inhibitors (BSL medium with µmax of 0.020/h. Higher level of synthetic inhibitors prolonged the lag phase, decreased the cell biomass and ethanol production, and specific growth rate. The strain could detoxify furfural and 5-HMF and produced the highest ethanol (Y(p/s of 0.32 g.g-1 when grown in BSL. Glucose was utilized as its level decreased in a result of increase in cell biomass, in contrast to xylose which was not consumed. The highest cell biomass was produced in YNB with Y (x/s value of 0.25 g.g-1. The strain produced acetic acid as a dominant side product and could convert furfural into a less toxic compound, hydroxyl furfural. This robust tolerant strain provides basic information on resistance mechanism and would be useful for bio-based cell factory using lignocellulosic materials. 

  5. Novel starters for old processes: use of Saccharomyces cerevisiae strains isolated from artisanal sourdough for craft beer production at a brewery scale.

    Marongiu, Antonella; Zara, Giacomo; Legras, Jean-Luc; Del Caro, Alessandra; Mascia, Ilaria; Fadda, Costantino; Budroni, Marilena

    2015-01-01

    The deliberate inoculation of yeast strains isolated from food matrices such as wine or bread, could allow the transfer of novel properties to beer. In this work, the feasibility of the use of baker's yeast strains as starters for craft beer production has been evaluated at laboratory and brewery scale. Nine out of 12 Saccharomyces cerevisiae strains isolated from artisanal sourdoughs metabolized 2 % maltose, glucose and trehalose and showed growth rates and cell populations higher than those of the brewer's strain Safbrew-S33. Analysis of allelic variation at 12 microsatellite loci clustered seven baker's strains and Safbrew-S33 in the main group of bread isolates. Chemical analyses of beers produced at a brewery scale showed significant differences among the beers produced with the baker's strain S38 or Safbrew-S33, while no significant differences were observed when S38 or the brewer's strain Safbrew-F2 was used for re-fermentation. The sensory profile of beers obtained with S38 or the brewer's yeasts did not show significant differences, thus suggesting that baker's strains of S. cerevisiae could represent a reservoir of biodiversity for the selection of starter strains for craft beer production.

  6. Benchmarking two commonly used Saccharomyces cerevisiae strains for heterologous vanillin-β-glucoside production

    Strucko, Tomas; Magdenoska, Olivera; Mortensen, Uffe Hasbro

    2015-01-01

    factories for production of specific compounds. To examine this possibility, we have reconstructed a de novo vanillin-β-glucoside pathway in an identical manner in S288c and CEN.PK strains. Characterization of the two resulting strains in two standard conditions revealed that the S288c background strain...... produced up to 10-fold higher amounts of vanillin-β-glucoside compared to CEN.PK. This study demonstrates that yeast strain background may play a major role in the outcome of newly developed cell factories for production of a given product....

  7. Genome-wide screen of Pseudomonas aeruginosa In Saccharomyces cerevisiae identifies new virulence factors

    Rafat eZrieq

    2015-11-01

    Full Text Available Pseudomonas aeruginosa is a human opportunistic pathogen that causes mortality in cystic fibrosis and immunocompromised patients. While many virulence factors of this pathogen have already been identified, several remain to be discovered. In this respect we set an unprecedented genome-wide screen of a P. aeruginosa expression library based on a yeast growth phenotype. 51 candidates were selected in a three-round screening process. The robustness of the screen was validated by the selection of three well known secreted proteins including one demonstrated virulence factor, the protease LepA. Further in silico sorting of the 51 candidates highlighted three potential new Pseudomonas effector candidates (Pec. By testing the cytotoxicity of wild type P. aeruginosa vs pec mutants towards macrophages and the virulence in the Caenorhabditis elegans model, we demonstrated that the three selected Pecs are novel virulence factors of P. aeruginosa. Additional cellular localization experiments in the host revealed specific localization for Pec1 and Pec2 that could inform about their respective functions.

  8. Glucose and maltose metabolism in MIG1-disrupted and MAL-constitutive strains of Saccharomyces cerevisiae

    Klein, Christopher; Olsson, Lisbeth; Rønnow, B

    1997-01-01

    in a mixed glucose-maltose medium revealed that the MAL-constitutive strains were more alleviated than the single MIG1-disrupted transformant. While all transformants exhibited higher maximum specific growth rates (0.24-0.25 h(-1)) in glucose-maltose mixtures than the wild type strain (0.20 h(-1)), the MAL-constitutive...

  9. Engineering industrial Saccharomyces cerevisiae strains for xylose fermentation and comparison for switchgrass conversion

    Saccharomyces physiology and fermentation related properties vary broadly among industrial strains. In this study, six industrial strains of varied genetic background were engineered to ferment xylose. Aerobic growth rates on xylose were 0.040 h**-1 to 0.167 h**-1. Fermentation of xylose, glucose/xy...

  10. Exploring grape marc as trove for new thermotolerant and inhibitor-tolerant Saccharomyces cerevisiae strains for second-generation bioethanol production.

    Favaro, Lorenzo; Basaglia, Marina; Trento, Alberto; Van Rensburg, Eugéne; García-Aparicio, Maria; Van Zyl, Willem H; Casella, Sergio

    2013-11-29

    Robust yeasts with high inhibitor, temperature, and osmotic tolerance remain a crucial requirement for the sustainable production of lignocellulosic bioethanol. These stress factors are known to severely hinder culture growth and fermentation performance. Grape marc was selected as an extreme environment to search for innately robust yeasts because of its limited nutrients, exposure to solar radiation, temperature fluctuations, weak acid and ethanol content. Forty newly isolated Saccharomyces cerevisiae strains gave high ethanol yields at 40°C when inoculated in minimal media at high sugar concentrations of up to 200 g/l glucose. In addition, the isolates displayed distinct inhibitor tolerance in defined broth supplemented with increasing levels of single inhibitors or with a cocktail containing several inhibitory compounds. Both the fermentation ability and inhibitor resistance of these strains were greater than those of established industrial and commercial S. cerevisiae yeasts used as control strains in this study. Liquor from steam-pretreated sugarcane bagasse was used as a key selective condition during the isolation of robust yeasts for industrial ethanol production, thus simulating the industrial environment. The isolate Fm17 produced the highest ethanol concentration (43.4 g/l) from the hydrolysate, despite relatively high concentrations of weak acids, furans, and phenolics. This strain also exhibited a significantly greater conversion rate of inhibitory furaldehydes compared with the reference strain S. cerevisiae 27P. To our knowledge, this is the first report describing a strain of S. cerevisiae able to produce an ethanol yield equal to 89% of theoretical maximum yield in the presence of high concentrations of inhibitors from sugarcane bagasse. This study showed that yeasts with high tolerance to multiple stress factors can be obtained from unconventional ecological niches. Grape marc appeared to be an unexplored and promising substrate for the

  11. Caffeine enhancement of radiation killing in different strains of Saccharomyces cerevisiae

    Hannan, M.A.; Nasim, A.

    1977-01-01

    Haploid and diploid wild type strains, and three classes of radiation-sensitive mutants of Saccharomyces cerrevisiae were tesed for enhancement of UV-inactivation by caffeine in growth medium. In addition the sensitizing effect of caffeine was studied in a haploid and a diploid wild type strain after gamma-irradiation. The drug sensitized the UV-irradiated cells of all strains except those reported to be only slightly UV-sensitive but highly sensitive to ionizing radiation. After gamma-irradiation, no coffeine-enhancement of killing was observed in stationary phase cells of either the haploid or the diploid strain. However, log-phase cells of both strains were partially sensitized. The results of both sets of experiments suggested that caffeine interferes with a recombinational repair occurring in cells in S or G2 phase. (orig.) [de

  12. Multi-gene phylogenetic analysis reveals that shochu-fermenting Saccharomyces cerevisiae strains form a distinct sub-clade of the Japanese sake cluster.

    Futagami, Taiki; Kadooka, Chihiro; Ando, Yoshinori; Okutsu, Kayu; Yoshizaki, Yumiko; Setoguchi, Shinji; Takamine, Kazunori; Kawai, Mikihiko; Tamaki, Hisanori

    2017-10-01

    Shochu is a traditional Japanese distilled spirit. The formation of the distinguishing flavour of shochu produced in individual distilleries is attributed to putative indigenous yeast strains. In this study, we performed the first (to our knowledge) phylogenetic classification of shochu strains based on nucleotide gene sequences. We performed phylogenetic classification of 21 putative indigenous shochu yeast strains isolated from 11 distilleries. All of these strains were shown or confirmed to be Saccharomyces cerevisiae, sharing species identification with 34 known S. cerevisiae strains (including commonly used shochu, sake, ale, whisky, bakery, bioethanol and laboratory yeast strains and clinical isolate) that were tested in parallel. Our analysis used five genes that reflect genome-level phylogeny for the strain-level classification. In a first step, we demonstrated that partial regions of the ZAP1, THI7, PXL1, YRR1 and GLG1 genes were sufficient to reproduce previous sub-species classifications. In a second step, these five analysed regions from each of 25 strains (four commonly used shochu strains and the 21 putative indigenous shochu strains) were concatenated and used to generate a phylogenetic tree. Further analysis revealed that the putative indigenous shochu yeast strains form a monophyletic group that includes both the shochu yeasts and a subset of the sake group strains; this cluster is a sister group to other sake yeast strains, together comprising a sake-shochu group. Differences among shochu strains were small, suggesting that it may be possible to correlate subtle phenotypic differences among shochu flavours with specific differences in genome sequences. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  13. High-level ethanol production from starch by a flocculent Saccharomyces cerevisiae strain displaying cell-surface glucoamylase

    Kondo, A.; Shigechi, H.; Abe, M.; Uyama, K. [Dept. of Chemical Science and Engineering, Kobe Univ., Nadaku, Kobe (Japan); Matsumoto, T.; Fukuda, H. [Div. of Molecular Science, Kobe Univ., Nadaku, Kobe (Japan); Takahashi, S.; Ueda, M.; Tanaka, A. [Dept. of Synthetic Chemistry and Biological Chemistry, Kyoto Univ., Sakyoku, Kyoto (Japan); Kishimoto, M. [Dept. of Biotechnology, Osaka Univ., Osaka (Japan)

    2002-07-01

    A Strain of host yeast YF207, which is a tryptophan auxotroph and shows strong flocculation ability, was obtained from Saccharomyces diastaticus ATCC60712 and S. cerevisiae W303-1B by tetrad analysis. The plasmid pGA11, which is a multicopy plasmid for cell-surface expression of the Rhyzopus oryzae glucoamylase/{alpha}-agglutinin fusion protein, was then introduced into this flocculent yeast strain (YF207/pGA11). Yeast YF207/pGA11 grew rapidly under aerobic condition (dissolved oxygen 2.0 ppm), using soluble starch. The harvested cells were used for batch fermentation of soluble starch to ethanol under anaerobic condition and showed high ethanol production rates (0.71 g h{sup -1} I{sup -1}) without a time lag, because glucoamylase was immobilized on the yeast cell surface. During repeated utilization of cells for fermentation, YF207/pGA11 maintained high ethanol production rates over 300 h. Moreover, in fed-batch fermentation with YF207/pGA11 for approximately 120 h, the ethanol concentration reached up to 50 g I{sup -1}. In conclusion, flocculent yeast cells displaying cell-surface glucoamylase are considered to be very effective for the direct fermentation of soluble starch to ethanol. (orig.)

  14. Co-fermentation using Recombinant Saccharomyces cerevisiae Yeast Strains Hyper-secreting Different Cellulases for the Production of Cellulosic Bioethanol.

    Lee, Cho-Ryong; Sung, Bong Hyun; Lim, Kwang-Mook; Kim, Mi-Jin; Sohn, Min Jeong; Bae, Jung-Hoon; Sohn, Jung-Hoon

    2017-06-30

    To realize the economical production of ethanol and other bio-based chemicals from lignocellulosic biomass by consolidated bioprocessing (CBP), various cellulases from different sources were tested to improve the level of cellulase secretion in the yeast Saccharomyces cerevisiae by screening an optimal translational fusion partner (TFP) as both a secretion signal and fusion partner. Among them, four indispensable cellulases for cellulose hydrolysis, including Chaetomium thermophilum cellobiohydrolase (CtCBH1), Chrysosporium lucknowense cellobiohydrolase (ClCBH2), Trichoderma reesei endoglucanase (TrEGL2), and Saccharomycopsis fibuligera β-glucosidase (SfBGL1), were identified to be highly secreted in active form in yeast. Despite variability in the enzyme levels produced, each recombinant yeast could secrete approximately 0.6-2.0 g/L of cellulases into the fermentation broth. The synergistic effect of the mixed culture of the four strains expressing the essential cellulases with the insoluble substrate Avicel and several types of cellulosic biomass was demonstrated to be effective. Co-fermentation of these yeast strains produced approximately 14 g/L ethanol from the pre-treated rice straw containing 35 g/L glucan with 3-fold higher productivity than that of wild type yeast using a reduced amount of commercial cellulases. This process will contribute to the cost-effective production of bioenergy such as bioethanol and biochemicals from cellulosic biomass.

  15. Comparative analysis on inactivation kinetics of between piezotolerant and piezosensitive mutant strains of Saccharomyces cerevisiae under combinations of high hydrostatic pressure and temperature.

    Nomura, Kazuki; Kuwabara, Yuki; Kuwabara, Wataru; Takahashi, Hiroyuki; Nakajima, Kanako; Hayashi, Mayumi; Iguchi, Akinori; Shigematsu, Toru

    2017-12-01

    We previously obtained a pressure-tolerant (piezotolerant) and a pressure sensitive (piezosensitive) mutant strain, under ambient temperature, from Saccharomyces cerevisiae strain KA31a. The inactivation kinetics of these mutants were analyzed at 150 to 250MPa with 4 to 40°C. By a multiple regression analysis, the pressure and temperature dependency of the inactivation rate constants k values of both mutants, as well as the parent strain KA31a, were well approximated with high correlation coefficients (0.92 to 0.95). For both mutants, as well as strain KA31a, the lowest k value was shown at a low pressure levels with around ambient temperature. The k value approximately increased with increase in pressure level, and with increase and decrease in temperature. The piezosensitive mutant strain a924E1 showed piezosensitivity at all pressure and temperature levels, compared with the parent strain KA31a. In contrast, the piezotolerant mutant strain a2568D8 showed piezotolerance at 4 to 20°C, but did not show significant piezotolerance at 40°C. These results of the variable influence of temperature on pressure inactivation of these strains would be important for better understanding of piezosensitive and piezotolerant mechanisms, as well as the pressure inactivation mechanism of S. cerevisiae. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Comparative transcriptomic analysis reveals similarities and dissimilarities in Saccharomyces cerevisiae wine strains response to nitrogen availability.

    Catarina Barbosa

    Full Text Available Nitrogen levels in grape-juices are of major importance in winemaking ensuring adequate yeast growth and fermentation performance. Here we used a comparative transcriptome analysis to uncover wine yeasts responses to nitrogen availability during fermentation. Gene expression was assessed in three genetically and phenotypically divergent commercial wine strains (CEG, VL1 and QA23, under low (67 mg/L and high nitrogen (670 mg/L regimes, at three time points during fermentation (12 h, 24 h and 96 h. Two-way ANOVA analysis of each fermentation condition led to the identification of genes whose expression was dependent on strain, fermentation stage and on the interaction of both factors. The high fermenter yeast strain QA23 was more clearly distinct from the other two strains, by differential expression of genes involved in flocculation, mitochondrial functions, energy generation and protein folding and stabilization. For all strains, higher transcriptional variability due to fermentation stage was seen in the high nitrogen fermentations. A positive correlation between maximum fermentation rate and the expression of genes involved in stress response was observed. The finding of common genes correlated with both fermentation activity and nitrogen up-take underlies the role of nitrogen on yeast fermentative fitness. The comparative analysis of genes differentially expressed between both fermentation conditions at 12 h, where the main difference was the level of nitrogen available, showed the highest variability amongst strains revealing strain-specific responses. Nevertheless, we were able to identify a small set of genes whose expression profiles can quantitatively assess the common response of the yeast strains to varying nitrogen conditions. The use of three contrasting yeast strains in gene expression analysis prompts the identification of more reliable, accurate and reproducible biomarkers that will facilitate the diagnosis of deficiency of this

  17. Comparative Transcriptomic Analysis Reveals Similarities and Dissimilarities in Saccharomyces cerevisiae Wine Strains Response to Nitrogen Availability

    Barbosa, Catarina; García-Martínez, José; Pérez-Ortín, José E.; Mendes-Ferreira, Ana

    2015-01-01

    Nitrogen levels in grape-juices are of major importance in winemaking ensuring adequate yeast growth and fermentation performance. Here we used a comparative transcriptome analysis to uncover wine yeasts responses to nitrogen availability during fermentation. Gene expression was assessed in three genetically and phenotypically divergent commercial wine strains (CEG, VL1 and QA23), under low (67 mg/L) and high nitrogen (670 mg/L) regimes, at three time points during fermentation (12h, 24h and 96h). Two-way ANOVA analysis of each fermentation condition led to the identification of genes whose expression was dependent on strain, fermentation stage and on the interaction of both factors. The high fermenter yeast strain QA23 was more clearly distinct from the other two strains, by differential expression of genes involved in flocculation, mitochondrial functions, energy generation and protein folding and stabilization. For all strains, higher transcriptional variability due to fermentation stage was seen in the high nitrogen fermentations. A positive correlation between maximum fermentation rate and the expression of genes involved in stress response was observed. The finding of common genes correlated with both fermentation activity and nitrogen up-take underlies the role of nitrogen on yeast fermentative fitness. The comparative analysis of genes differentially expressed between both fermentation conditions at 12h, where the main difference was the level of nitrogen available, showed the highest variability amongst strains revealing strain-specific responses. Nevertheless, we were able to identify a small set of genes whose expression profiles can quantitatively assess the common response of the yeast strains to varying nitrogen conditions. The use of three contrasting yeast strains in gene expression analysis prompts the identification of more reliable, accurate and reproducible biomarkers that will facilitate the diagnosis of deficiency of this nutrient in the grape

  18. Oxygen availability and strain combination modulate yeast growth dynamics in mixed culture fermentations of grape must with Starmerella bacillaris and Saccharomyces cerevisiae.

    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.

  19. Variation in Indole-3-Acetic Acid Production by Wild Saccharomyces cerevisiae and S. paradoxus Strains from Diverse Ecological Sources and Its Effect on Growth.

    Liu, Yen-Yu; Chen, Hung-Wei; Chou, Jui-Yu

    2016-01-01

    Phytohormone indole-3-acetic acid (IAA) is the most common naturally occurring and most thoroughly studied plant growth regulator. Microbial synthesis of IAA has long been known. Microbial IAA biosynthesis has been proposed as possibly occurring through multiple pathways, as has been proven in plants. However, the biosynthetic pathways of IAA and the ecological roles of IAA in yeast have not been widely studied. In this study, we investigated the variation in IAA production and its effect on the growth of Saccharomyces cerevisiae and its closest relative Saccharomyces paradoxus yeasts from diverse ecological sources. We found that almost all Saccharomyces yeasts produced IAA when cultured in medium supplemented with the primary precursor of IAA, L-tryptophan (L-Trp). However, when cultured in medium without L-Trp, IAA production was only detected in three strains. Furthermore, exogenous added IAA exerted stimulatory and inhibitory effects on yeast growth. Interestingly, a negative correlation was observed between the amount of IAA production in the yeast cultures and the IAA inhibition ratio of their growth.

  20. The genome-wide early temporal response of Saccharomyces cerevisiae to oxidative stress induced by cumene hydroperoxide.

    Wei Sha

    Full Text Available Oxidative stress is a well-known biological process that occurs in all respiring cells and is involved in pathophysiological processes such as aging and apoptosis. Oxidative stress agents include peroxides such as hydrogen peroxide, cumene hydroperoxide, and linoleic acid hydroperoxide, the thiol oxidant diamide, and menadione, a generator of superoxide, amongst others. The present study analyzed the early temporal genome-wide transcriptional response of Saccharomyces cerevisiae to oxidative stress induced by the aromatic peroxide cumene hydroperoxide. The accurate dataset obtained, supported by the use of temporal controls, biological replicates and well controlled growth conditions, provided a detailed picture of the early dynamics of the process. We identified a set of genes previously not implicated in the oxidative stress response, including several transcriptional regulators showing a fast transient response, suggesting a coordinated process in the transcriptional reprogramming. We discuss the role of the glutathione, thioredoxin and reactive oxygen species-removing systems, the proteasome and the pentose phosphate pathway. A data-driven clustering of the expression patterns identified one specific cluster that mostly consisted of genes known to be regulated by the Yap1p and Skn7p transcription factors, emphasizing their mediator role in the transcriptional response to oxidants. Comparison of our results with data reported for hydrogen peroxide identified 664 genes that specifically respond to cumene hydroperoxide, suggesting distinct transcriptional responses to these two peroxides. Genes up-regulated only by cumene hydroperoxide are mainly related to the cell membrane and cell wall, and proteolysis process, while those down-regulated only by this aromatic peroxide are involved in mitochondrial function.

  1. A genome-wide immunodetection screen in S. cerevisiae uncovers novel genes involved in lysosomal vacuole function and morphology.

    Florante Ricarte

    Full Text Available Vacuoles of yeast Saccharomyces cerevisiae are functionally analogous to mammalian lysosomes. Both are cellular organelles responsible for macromolecular degradation, ion/pH homeostasis, and stress survival. We hypothesized that undefined gene functions remain at post-endosomal stage of vacuolar events and performed a genome-wide screen directed at such functions at the late endosome and vacuole interface - ENV genes. The immunodetection screen was designed to identify mutants that internally accumulate precursor form of the vacuolar hydrolase carboxypeptidase Y (CPY. Here, we report the uncovering and initial characterizations of twelve ENV genes. The small size of the collection and the lack of genes previously identified with vacuolar events are suggestive of the intended exclusive functional interface of the screen. Most notably, the collection includes four novel genes ENV7, ENV9, ENV10, and ENV11, and three genes previously linked to mitochondrial processes - MAM3, PCP1, PPE1. In all env mutants, vesicular trafficking stages were undisturbed in live cells as assessed by invertase and active α-factor secretion, as well as by localization of the endocytic fluorescent marker FM4-64 to the vacuole. Several mutants exhibit defects in stress survival functions associated with vacuoles. Confocal fluorescence microscopy revealed the collection to be significantly enriched in vacuolar morphologies suggestive of fusion and fission defects. These include the unique phenotype of lumenal vesicles within vacuoles in the novel env9Δ mutant and severely fragmented vacuoles upon deletion of GET4, a gene recently implicated in tail anchored membrane protein insertion. Thus, our results establish new gene functions in vacuolar function and morphology, and suggest a link between vacuolar and mitochondrial events.

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

    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.

  3. CRISPR–Cas system enables fast and simple genome editing of industrial Saccharomyces cerevisiae strains

    Stovicek, Vratislav; Borodina, Irina; Förster, Jochen

    2015-01-01

    , their genetic manipulation is challenging, as they are usually diploid or polyploid. Therefore, there is a need to develop more efficient genetic engineering tools. We applied a CRISPR–Cas9 system for genome editing of different industrial strains, and show simultaneous disruption of two alleles of a gene...... in several unrelated strains with the efficiency ranging between 65% and 78%. We also achieved simultaneous disruption and knock-in of a reporter gene, and demonstrate the applicability of the method by designing lactic acid-producing strains in a single transformation event, where insertion...... of a heterologous gene and disruption of two endogenous genes occurred simultaneously. Our study provides a foundation for efficient engineering of industrial yeast cell factories....

  4. Comparisons of five Saccharomyces cerevisiae strains for ethanol production from SPORL pretreated lodgepole pine

    The performances of 5 yeast strains under three levels of toxicity were evaluated using hydrolysates from lodgepole pine pretreated by Sulfite Pretreatment to Overcome the Recalcitrance of Lignocelluloses (SPORL). The highest level of toxicity was represented by the whole pretreated biomass slurry, ...

  5. Comparisons of five Saccharomyces cerevisiae strains for ethanol production from SPORL pretreated lodgepole pine

    Haifeng Zhou; Tianqing Lan; Bruce S. Dien; Ronald E. Hector; J.Y. Zhu

    2014-01-01

    The performances of five yeast strains under three levels of toxicity were evaluated using hydrolysates from lodgepole pine pretreated by Sulfite Pretreatment to Overcome the Recalcitrance of Lignocelluloses (SPORL). The highest level of toxicity was represented by the whole pretreated biomass slurry, while intermediate toxicity was represented by the...

  6. De novo production of six key grape aroma monoterpenes by a geraniol synthase-engineered S. cerevisiae wine strain.

    Pardo, Ester; Rico, Juan; Gil, José Vicente; Orejas, Margarita

    2015-09-16

    Monoterpenes are important contributors to grape and wine aroma. Moreover, certain monoterpenes have been shown to display health benefits with antimicrobial, anti-inflammatory, anticancer or hypotensive properties amongst others. The aim of this study was to construct self-aromatizing wine yeasts to overproduce de novo these plant metabolites in wines. Expression of the Ocimum basilicum (sweet basil) geraniol synthase (GES) gene in a Saccharomyces cerevisiae wine strain substantially changed the terpene profile of wine produced from a non-aromatic grape variety. Under microvinification conditions, and without compromising other fermentative traits, the recombinant yeast excreted geraniol de novo at an amount (~750 μg/L) well exceeding (>10-fold) its threshold for olfactory perception and also exceeding the quantities present in wines obtained from highly aromatic Muscat grapes. Interestingly, geraniol was further metabolized by yeast enzymes to additional monoterpenes and esters: citronellol, linalool, nerol, citronellyl acetate and geranyl acetate, resulting in a total monoterpene concentration (~1,558 μg/L) 230-fold greater than that of the control. We also found that monoterpene profiles of wines derived from mixed fermentations were found to be determined by the composition of the initial yeast inocula suggesting the feasibility of producing 'à la carte' wines having predetermined monoterpene contents. Geraniol synthase-engineered yeasts demonstrate potential in the development of monoterpene enhanced wines.

  7. The yeast culture Saccharomyces cerevisiae (Strain 47 as manipulator of rumen fermentation in postpartal period of dairy cows

    Petr Doležal

    2005-01-01

    Full Text Available In the present study, examined was the effect of a yeast culture (Saccharomyces cerevisiae, Strain 47 on rumen fermentation of cows. Animals received a diet consisting of good maize silage with a higher dry matter content (16  kg, 16  kg of clovergrass haylage, 3  kg of meadow hay and 7.5  kg feed mixture. The yeast culture was added to the mixture in the dose 6  g/day and cow. The supplement of yeast culture showed a positive effect on VFA production in comparison with control (1.16±0.013B vs. 0.84±0.063A  g/ 100 ml, and lower production of lactic acid. The utilisation of ammonia was higher by cows in treated group (8.68±0.084A mmol/L. The difference in number of protozoa of cows in the control and experimental groups was significant (302.0±12.349A vs. 359.2±1.304B ths /1 ml of rumen fluid.

  8. Succinate Dehydrogenase Activity Assay in situ with Blue Tetrazolium Salt in Crabtree-Positive Saccharomyces cerevisiae Strain

    Joanna Berlowska

    2008-01-01

    Full Text Available A spectrophotometric method for determining succinate dehydrogenase (SDH activity assay in azide-sensitive yeast Saccharomyces cerevisiae has been developed. The permeabilization of yeast cells by 0.05 % digitonin permitted to study yeast enzymatic activity in situ. The reduction of blue tetrazolium salt (BT to blue tetrazolium formazan (BTf was conducted in the presence of phenazine methosulphate (PMS as an exogenous electron carrier, and sodium azide (SA as an inhibitor of cytochrome oxidase (Cyt pathway. Various factors such as type of substrate, BT concentration, cell number, temperature and time of incubation, and different Cyt pathway blockers were optimized. In earlier studies, dimethyl sulfoxide (DMSO had been selected as the best solvent for extraction of BTf from yeast cells. The linear correlation between permeabilized yeast cell density and amount of formed formazan was evidenced in the range from 9·10^7 to 5·10^8 cells per sample solution. Below the yeast cell concentration of 10^7 the absorbance values were too low to detect formazans with good precision. This standarized procedure allows the estimation of SDH activity in whole cells, depending on vitality level of yeast populations. Significant increases of succinate dehydrogenase activities were observed in sequential passages as the result of the increase of activity of the strain and adaptation to cultivation conditions.

  9. Growth-rate dependency of de novo resveratrol production in chemostat cultures of an engineered Saccharomyces cerevisiae strain

    Vos, T.; De la Torre Cortes, P.; Van Gulik, W.M.; Pronk, J.T.; Daran-Lapujade, P.A.S.

    2015-01-01

    Introduction: Saccharomyces cerevisiae has become a popular host for production of non-native compounds. The metabolic pathways involved generally require a net input of energy. To maximize the ATP yield on sugar in S. cerevisiae, industrial cultivation is typically performed in aerobic,

  10. Optimizing anaerobic growth rate and fermentation kinetics in Saccharomyces cerevisiae strains expressing Calvin-cycle enzymes for improved ethanol yield

    Papapetridis, I.; Goudriaan, M.; De Keijzer, Nikita A.; van den Broek, M.A.; van Maris, A.J.A.; Pronk, J.T.

    2018-01-01

    Background: Reduction or elimination of by-product formation is of immediate economic relevance in fermentation processes for industrial bioethanol production with the yeast Saccharomyces cerevisiae. Anaerobic cultures of wild-type S. cerevisiae require formation of glycerol to maintain the

  11. A wide extent of inter-strain diversity in virulent and vaccine strains of alphaherpesviruses.

    Moriah L Szpara

    2011-10-01

    Full Text Available Alphaherpesviruses are widespread in the human population, and include herpes simplex virus 1 (HSV-1 and 2, and varicella zoster virus (VZV. These viral pathogens cause epithelial lesions, and then infect the nervous system to cause lifelong latency, reactivation, and spread. A related veterinary herpesvirus, pseudorabies (PRV, causes similar disease in livestock that result in significant economic losses. Vaccines developed for VZV and PRV serve as useful models for the development of an HSV-1 vaccine. We present full genome sequence comparisons of the PRV vaccine strain Bartha, and two virulent PRV isolates, Kaplan and Becker. These genome sequences were determined by high-throughput sequencing and assembly, and present new insights into the attenuation of a mammalian alphaherpesvirus vaccine strain. We find many previously unknown coding differences between PRV Bartha and the virulent strains, including changes to the fusion proteins gH and gB, and over forty other viral proteins. Inter-strain variation in PRV protein sequences is much closer to levels previously observed for HSV-1 than for the highly stable VZV proteome. Almost 20% of the PRV genome contains tandem short sequence repeats (SSRs, a class of nucleic acids motifs whose length-variation has been associated with changes in DNA binding site efficiency, transcriptional regulation, and protein interactions. We find SSRs throughout the herpesvirus family, and provide the first global characterization of SSRs in viruses, both within and between strains. We find SSR length variation between different isolates of PRV and HSV-1, which may provide a new mechanism for phenotypic variation between strains. Finally, we detected a small number of polymorphic bases within each plaque-purified PRV strain, and we characterize the effect of passage and plaque-purification on these polymorphisms. These data add to growing evidence that even plaque-purified stocks of stable DNA viruses exhibit

  12. A wide extent of inter-strain diversity in virulent and vaccine strains of alphaherpesviruses.

    Szpara, Moriah L; Tafuri, Yolanda R; Parsons, Lance; Shamim, S Rafi; Verstrepen, Kevin J; Legendre, Matthieu; Enquist, L W

    2011-10-01

    Alphaherpesviruses are widespread in the human population, and include herpes simplex virus 1 (HSV-1) and 2, and varicella zoster virus (VZV). These viral pathogens cause epithelial lesions, and then infect the nervous system to cause lifelong latency, reactivation, and spread. A related veterinary herpesvirus, pseudorabies (PRV), causes similar disease in livestock that result in significant economic losses. Vaccines developed for VZV and PRV serve as useful models for the development of an HSV-1 vaccine. We present full genome sequence comparisons of the PRV vaccine strain Bartha, and two virulent PRV isolates, Kaplan and Becker. These genome sequences were determined by high-throughput sequencing and assembly, and present new insights into the attenuation of a mammalian alphaherpesvirus vaccine strain. We find many previously unknown coding differences between PRV Bartha and the virulent strains, including changes to the fusion proteins gH and gB, and over forty other viral proteins. Inter-strain variation in PRV protein sequences is much closer to levels previously observed for HSV-1 than for the highly stable VZV proteome. Almost 20% of the PRV genome contains tandem short sequence repeats (SSRs), a class of nucleic acids motifs whose length-variation has been associated with changes in DNA binding site efficiency, transcriptional regulation, and protein interactions. We find SSRs throughout the herpesvirus family, and provide the first global characterization of SSRs in viruses, both within and between strains. We find SSR length variation between different isolates of PRV and HSV-1, which may provide a new mechanism for phenotypic variation between strains. Finally, we detected a small number of polymorphic bases within each plaque-purified PRV strain, and we characterize the effect of passage and plaque-purification on these polymorphisms. These data add to growing evidence that even plaque-purified stocks of stable DNA viruses exhibit limited sequence

  13. Comparisons of five Saccharomyces cerevisiae strains for ethanol production from SPORL-pretreated lodgepole pine.

    Zhou, Haifeng; Lan, Tianqing; Dien, Bruce S; Hector, Ronald E; Zhu, J Y

    2014-01-01

    The performances of five yeast strains under three levels of toxicity were evaluated using hydrolysates from lodgepole pine pretreated by Sulfite Pretreatment to Overcome the Recalcitrance of Lignocelluloses (SPORL). The highest level of toxicity was represented by the whole pretreated biomass slurry, while intermediate toxicity was represented by the hydrolysate with partial loading of pretreatment spent liquor. The zero toxicity was represented using the enzymatic hydrolysate produced from thoroughly washed SPORL lodgepole pine solids. The results indicate that strains D5A and YRH400 can tolerate the whole pretreated biomass slurry to produce 90.1 and 73.5% theoretical ethanol yield. Strains Y1528, YRH403, and FPL450 did not grow in whole hydrolysate cultures and were observed to have lower ethanol productivities than D5A and YRH400 on the hydrolysate with intermediate toxicity. Both YRH400 and YRH403 were genetically engineered for xylose fermentation but were not able to consume xylose efficiently in hydrolysate. © 2014 American Institute of Chemical Engineers.

  14. Enhanced 3-sulfanylhexan-1-ol production in sequential mixed fermentation with Torulaspora delbrueckii/Saccharomyces cerevisiae reveals a situation of synergistic interaction between two industrial strains

    Philippe eRenault

    2016-03-01

    Full Text Available The aim of this work was to study the volatile thiol productions of 2 industrial strains of Torulaspora delbrueckii and Saccharomyces cerevisiae during alcoholic fermentation (AF of Sauvignon Blanc must. In order to evaluate the influence of the inoculation procedure, sequential and simultaneous mixed cultures were carried out and compared to pure cultures of T. delbrueckii and S. cerevisiae. The results confirmed the inability of T. delbrueckii to release 4-methyl-4-sulfanylpentan-2-one (4MSP and its low capacity to produce 3-sulfanylhexyl acetate (3SHA, as already reported in previous studies. A synergistic interaction was observed between the two species, resulting in higher levels of 3SH (3-sulfanylhexan-1-ol and its acetate when S. cerevisiae was inoculated 24 hours after T. delbrueckii, compared to the pure cultures. To elucidate the nature of the interactions between these 2 species, the yeast population kinetics were examined and monitored, as well as the production of 3SH, its acetate and their related non-odorous precursors: Glut-3SH (glutathionylated conjugate precursor and Cys-3SH (cysteinylated conjugate precursor. For the first time, it was suggested that, unlike, S. cerevisiae, which is able to metabolize the two precursor forms, T. delbrueckii was only able to metabolize the glutathionylated precursor. Consequently, the presence of T. delbrueckii during mixed fermentation led to an increase in Glut-3SH degradation and Cys-3SH production. This overproduction was dependent on the T. delbrueckii biomass. In sequential culture, thus favouring T. delbrueckii development, the higher availability of Cys-3SH throughout AF (alcoholic fermentation resulted in more abundant 3SH and 3SHA production by S. cerevisiae

  15. Enhanced 3-Sulfanylhexan-1-ol Production in Sequential Mixed Fermentation with Torulaspora delbrueckii/Saccharomyces cerevisiae Reveals a Situation of Synergistic Interaction between Two Industrial Strains.

    Renault, Philippe; Coulon, Joana; Moine, Virginie; Thibon, Cécile; Bely, Marina

    2016-01-01

    The aim of this work was to study the volatile thiol productions of two industrial strains of Torulaspora delbrueckii and Saccharomyces cerevisiae during alcoholic fermentation (AF) of Sauvignon Blanc must. In order to evaluate the influence of the inoculation procedure, sequential and simultaneous mixed cultures were carried out and compared to pure cultures of T. delbrueckii and S. cerevisiae. The results confirmed the inability of T. delbrueckii to release 4-methyl-4-sulfanylpentan-2-one (4MSP) and its low capacity to produce 3-sulfanylhexyl acetate (3SHA), as already reported in previous studies. A synergistic interaction was observed between the two species, resulting in higher levels of 3SH (3-sulfanylhexan-1-ol) and its acetate when S. cerevisiae was inoculated 24 h after T. delbrueckii, compared to the pure cultures. To elucidate the nature of the interactions between these two species, the yeast population kinetics were examined and monitored, as well as the production of 3SH, its acetate and their related non-odorous precursors: Glut-3SH (glutathionylated conjugate precursor) and Cys-3SH (cysteinylated conjugate precursor). For the first time, it was suggested that, unlike S. cerevisiae, which is able to metabolize the two precursor forms, T. delbrueckii was only able to metabolize the glutathionylated precursor. Consequently, the presence of T. delbrueckii during mixed fermentation led to an increase in Glut-3SH degradation and Cys-3SH production. This overproduction was dependent on the T. delbrueckii biomass. In sequential culture, thus favoring T. delbrueckii development, the higher availability of Cys-3SH throughout AF resulted in more abundant 3SH and 3SHA production by S. cerevisiae.

  16. Modelling plastic deformation of metals over a wide range of strain rates using irreversible thermodynamics

    Huang Mingxin; Rivera-Diaz-del-Castillo, Pedro E J; Zwaag, Sybrand van der; Bouaziz, Olivier

    2009-01-01

    Based on the theory of irreversible thermodynamics, the present work proposes a dislocation-based model to describe the plastic deformation of FCC metals over wide ranges of strain rates. The stress-strain behaviour and the evolution of the average dislocation density are derived. It is found that there is a transitional strain rate (∼ 10 4 s -1 ) over which the phonon drag effects appear, resulting in a significant increase in the flow stress and the average dislocation density. The model is applied to pure Cu deformed at room temperature and at strain rates ranging from 10 -5 to 10 6 s -1 showing good agreement with experimental results.

  17. Ethanol production from kitchen waste using the flocculating yeast Saccharomyces cerevisiae strain KF-7

    Tang, Yue-Qin; Liu, Kai; An, Ming-Zhe; Morimura, Shigeru; Kida, Kenji [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Koike, Yoji [Tokyo Gas Co., Ltd., 1-7-7 Suehiro-cho, Tsurumi-ku, Yokohama City, Kanagawa 230-0045 (Japan); Wu, Xiao-Lei [Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871 (China)

    2008-11-15

    A process for producing ethanol from kitchen waste was developed in this study. The process consists of freshness preservation of the waste, saccharification of the sugars in the waste, continuous ethanol fermentation of the saccharified liquid, and anaerobic treatment of the saccharification residue and the stillage. Spraying lactic acid bacteria (LCB) on the kitchen waste kept the waste fresh for over 1 week. High glucose recovery (85.5%) from LCB-sprayed waste was achieved after saccharification using Nagase N-40 glucoamylase. The resulting saccharified liquid was used directly for ethanol fermentation, without the addition of any nutrients. High ethanol productivity (24.0 g l{sup -1} h{sup -1}) was obtained when the flocculating yeast strain KF-7 was used in a continuous ethanol fermentation process at a dilution rate of 0.8 h{sup -1}. The saccharification residue was mixed with stillage and treated in a thermophilic anaerobic continuous stirred tank reactor (CSTR); a VTS loading rate of 6 g l{sup -1} d{sup -1} with 72% VTS digestion efficiency was achieved. Using this process, 30.9 g ethanol, and 65.2 l biogas with 50% methane, was produced from 1 kg of kitchen waste containing 118.0 g total sugar. Thus, energy in kitchen waste can be converted to ethanol and methane, which can then be used as fuels, while simultaneously treating kitchen waste. (author)

  18. Ethanol production from kitchen waste using the flocculating yeast Saccharomyces cerevisiae strain KF-7

    Tang, Y.-Q.; Koike, Yoji; Liu Kai; An, M.-Z.; Morimura, Shigeru; Wu Xiaolei; Kida, Kenji

    2008-01-01

    A process for producing ethanol from kitchen waste was developed in this study. The process consists of freshness preservation of the waste, saccharification of the sugars in the waste, continuous ethanol fermentation of the saccharified liquid, and anaerobic treatment of the saccharification residue and the stillage. Spraying lactic acid bacteria (LCB) on the kitchen waste kept the waste fresh for over 1 week. High glucose recovery (85.5%) from LCB-sprayed waste was achieved after saccharification using Nagase N-40 glucoamylase. The resulting saccharified liquid was used directly for ethanol fermentation, without the addition of any nutrients. High ethanol productivity (24.0 g l -1 h -1 ) was obtained when the flocculating yeast strain KF-7 was used in a continuous ethanol fermentation process at a dilution rate of 0.8 h -1 . The saccharification residue was mixed with stillage and treated in a thermophilic anaerobic continuous stirred tank reactor (CSTR); a VTS loading rate of 6 g l -1 d -1 with 72% VTS digestion efficiency was achieved. Using this process, 30.9 g ethanol, and 65.2 l biogas with 50% methane, was produced from 1 kg of kitchen waste containing 118.0 g total sugar. Thus, energy in kitchen waste can be converted to ethanol and methane, which can then be used as fuels, while simultaneously treating kitchen waste

  19. Mechanistic Study of Utilization of Water-Insoluble Saccharomyces cerevisiae Glucans by Bifidobacterium breve Strain JCM1192.

    Keung, Hoi Yee; Li, Tsz Kai; Sham, Lok To; Cheung, Man Kit; Cheung, Peter Chi Keung; Kwan, Hoi Shan

    2017-04-01

    Bifidobacteria exert beneficial effects on hosts and are extensively used as probiotics. However, due to the genetic inaccessibility of these bacteria, little is known about their mechanisms of carbohydrate utilization and regulation. Bifidobacterium breve strain JCM1192 can grow on water-insoluble yeast ( Saccharomyces cerevisiae ) cell wall glucans (YCWG), which were recently considered as potential prebiotics. According to the results of 1 H nuclear magnetic resonance (NMR) spectrometry, the YCWG were composed of highly branched (1→3,1→6)-β-glucans and (1→4,1→6)-α-glucans. Although the YCWG were composed of 78.3% β-glucans and 21.7% α-glucans, only α-glucans were consumed by the B. breve strain. The ABC transporter ( malEFG1 ) and pullulanase ( aapA ) genes were transcriptionally upregulated in the metabolism of insoluble yeast glucans, suggesting their potential involvement in the process. A nonsense mutation identified in the gene encoding an ABC transporter ATP-binding protein (MalK) led to growth failure of an ethyl methanesulfonate-generated mutant with yeast glucans. Coculture of the wild-type strain and the mutant showed that this protein was responsible for the import of yeast glucans or their breakdown products, rather than the export of α-glucan-catabolizing enzymes. Further characterization of the carbohydrate utilization of the mutant and three of its revertants indicated that this mutation was pleiotropic: the mutant could not grow with maltose, glycogen, dextrin, raffinose, cellobiose, melibiose, or turanose. We propose that insoluble yeast α-glucans are hydrolyzed by extracellular pullulanase into maltose and/or maltooligosaccharides, which are then transported into the cell by the ABC transport system composed of MalEFG1 and MalK. The mechanism elucidated here will facilitate the development of B. breve and water-insoluble yeast glucans as novel synbiotics. IMPORTANCE In general, Bifidobacterium strains are genetically intractable

  20. Fiber Strain Measurement for Wide Region Quasidistributed Sensing by Optical Correlation Sensor with Region Separation Techniques

    Xunjian Xu

    2010-01-01

    Full Text Available The useful application of optical pulse correlation sensor for wide region quasidistributed fiber strain measurement is investigated. Using region separation techniques of wavelength multiplexing with FBGs and time multiplexing with intensity partial reflectors, the sensor measures the correlations between reference pulses and monitoring pulses from several cascadable selected sensing regions. This novel sensing system can select the regions and obtain the distributed strain information in any desired sensing region.

  1. The effect of temperature on the growth of strains of Kloeckera apiculata and Saccharomyces cerevisiae in apple juice fermentation.

    Bilbao, A; Irastorza, A; Dueñas, M; Fernandez, K

    1997-01-01

    The influence of temperature (10 degrees C and 25 degrees C) on the survival and growth of Saccharomyces cerevisiae and Kloeckera apiculata was examined in mixed and pure cultures during fermentation in apple juice. The growth reached by S. cerevisiae did not seem to be affected by temperature and the presence of K. apiculata. However, the growth and survival of K. apiculata, both in single and mixed cultures, were substantially enhanced at 10 degrees C. The highest amount of ethyl acetate was produced by K. apiculata in pure culture at 10 degrees C. Nevertheless, this concentration was lowest when both yeasts were fermented together at 10 degrees C and 25 degrees C.

  2. Biochemical and Molecular Characterization of Saccharomyces cerevisiae Strains Obtained from Sugar-Cane Juice Fermentations and Their Impact in Cachaça Production▿

    Oliveira, Valdinéia Aparecida; Vicente, Maristela Araújo; Fietto, Luciano Gomes; de Miranda Castro, Ieso; Coutrim, Maurício Xavier; Schüller, Dorit; Alves, Henrique; Casal, Margarida; de Oliveira Santos, Juliana; Araújo, Leandro Dias; da Silva, Paulo Henrique Alves; Brandão, Rogelio Lopes

    2008-01-01

    Saccharomyces cerevisiae strains from different regions of Minas Gerais, Brazil, were isolated and characterized aiming at the selection of starter yeasts to be used in the production of cachaça, the Brazilian sugar cane spirit. The methodology established took into account the screening for biochemical traits desirable in a yeast cachaça producer, such as no H2S production, high tolerance to ethanol and high temperatures, high fermentative capacity, and the abilities to flocculate and to produce mycocins. Furthermore, the yeasts were exposed to drugs such as 5,5′,5"-trifluor-d,l-leucine and cerulenin to isolate those that potentially overproduce higher alcohols and esters. The utilization of a random amplified polymorphic DNA-PCR method with primers based on intron splicing sites flanking regions of the COX1 gene, as well as microsatellite analysis, was not sufficient to achieve good differentiation among selected strains. In contrast, karyotype analysis allowed a clear distinction among all strains. Two selected strains were experimentally evaluated as cachaça producers. The results suggest that the selection of strains as fermentation starters requires the combined use of biochemical and molecular criteria to ensure the isolation and identification of strains with potential characteristics to produce cachaça with a higher quality standard. PMID:18065624

  3. Phenotypic selection of a wild Saccharomyces cerevisiae strain for simultaneous saccharification and co-fermentation of AFEX pretreated corn stover

    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,...

  4. Dynamic study of yeast species and Saccharomyces cerevisiae strains during the spontaneous fermentations of Muscat blanc in Jingyang, China.

    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.

  5. Wide bandgap, strain-balanced quantum well tunnel junctions on InP substrates

    Lumb, M. P.; Yakes, M. K.; Schmieder, K. J.; Affouda, C. A.; Walters, R. J.; González, M.; Bennett, M. F.; Herrera, M.; Delgado, F. J.; Molina, S. I.

    2016-01-01

    In this work, the electrical performance of strain-balanced quantum well tunnel junctions with varying designs is presented. Strain-balanced quantum well tunnel junctions comprising compressively strained InAlAs wells and tensile-strained InAlAs barriers were grown on InP substrates using solid-source molecular beam epitaxy. The use of InAlAs enables InP-based tunnel junction devices to be produced using wide bandgap layers, enabling high electrical performance with low absorption. The impact of well and barrier thickness on the electrical performance was investigated, in addition to the impact of Si and Be doping concentration. Finally, the impact of an InGaAs quantum well at the junction interface is presented, enabling a peak tunnel current density of 47.6 A/cm 2 to be realized.

  6. Wide bandgap, strain-balanced quantum well tunnel junctions on InP substrates

    Lumb, M. P. [The George Washington University, Washington, DC 20037 (United States); US Naval Research Laboratory, Washington, DC 20375 (United States); Yakes, M. K.; Schmieder, K. J.; Affouda, C. A.; Walters, R. J. [US Naval Research Laboratory, Washington, DC 20375 (United States); González, M.; Bennett, M. F. [Sotera Defense Solutions, Annapolis Junction, Maryland 20701 (United States); US Naval Research Laboratory, Washington, DC 20375 (United States); Herrera, M.; Delgado, F. J.; Molina, S. I. [University of Cádiz, 11510, Puerto Real, Cádiz (Spain)

    2016-05-21

    In this work, the electrical performance of strain-balanced quantum well tunnel junctions with varying designs is presented. Strain-balanced quantum well tunnel junctions comprising compressively strained InAlAs wells and tensile-strained InAlAs barriers were grown on InP substrates using solid-source molecular beam epitaxy. The use of InAlAs enables InP-based tunnel junction devices to be produced using wide bandgap layers, enabling high electrical performance with low absorption. The impact of well and barrier thickness on the electrical performance was investigated, in addition to the impact of Si and Be doping concentration. Finally, the impact of an InGaAs quantum well at the junction interface is presented, enabling a peak tunnel current density of 47.6 A/cm{sup 2} to be realized.

  7. Enhancing ethanol yields through d-xylose and l-arabinose co-fermentation after construction of a novel high efficient l-arabinose-fermenting Saccharomyces cerevisiae strain.

    Caballero, Antonio; Ramos, Juan Luis

    2017-04-01

    Lignocellulose contains two pentose sugars, l-arabinose and d-xylose, neither of which is naturally fermented by first generation (1G) ethanol-producing Saccharomyces cerevisiae yeast. Since these sugars are inaccessible to 1G yeast, a significant percentage of the total carbon in bioethanol production from plant residues, which are used in second generation (2G) ethanol production, remains unused. Recombinant Saccharomyces cerevisiae strains capable of fermenting d-xylose are available on the market; however, there are few examples of l-arabinose-fermenting yeasts, and commercially, there are no strains capable of fermenting both d-xylose and l-arabinose because of metabolic incompatibilities when both metabolic pathways are expressed in the same cell. To attempt to solve this problem we have tested d-xylose and l-arabinose co-fermentation. To find efficient alternative l-arabinose utilization pathways to the few existing ones, we have used stringent methodology to screen for new genes (metabolic and transporter functions) to facilitate l-arabinose fermentation in recombinant yeast. We demonstrate the feasibility of this approach in a successfully constructed yeast strain capable of using l-arabinose as the sole carbon source and capable of fully transforming it to ethanol, reaching the maximum theoretical fermentation yield (0.43 g g-1). We demonstrate that efficient co-fermentation of d-xylose and l-arabinose is feasible using two different co-cultured strains, and observed no fermentation delays, yield drops or accumulation of undesired byproducts. In this study we have identified a technically efficient strategy to enhance ethanol yields by 10 % in 2G plants in a process based on C5 sugar co-fermentation.

  8. Effects of fermentation by Saccharomyces cerevisiae and ...

    yassine

    2013-02-13

    Feb 13, 2013 ... Effect of Saccharomyces cerevisiae fermentation on the ... beetroot, fermentation, Saccharomyces cerevisiae, betalain compounds. ... by Saccharomyces cerevisiae strains (González et al., .... Both red and yellow pigments were influenced during S. .... in beverages such as white wine, grape fruit, and green.

  9. Function of SSA subfamily of Hsp70 within and across species varies widely in complementing Saccharomyces cerevisiae cell growth and prion propagation.

    Deepak Sharma

    2009-08-01

    Full Text Available The cytosol of most eukaryotic cells contains multiple highly conserved Hsp70 orthologs that differ mainly by their spatio-temporal expression patterns. Hsp70s play essential roles in protein folding, transport or degradation, and are major players of cellular quality control processes. However, while several reports suggest that specialized functions of Hsp70 orthologs were selected through evolution, few studies addressed systematically this issue.We compared the ability of Ssa1p-Ssa4p from Saccharomyces cerevisiae and Ssa5p-Ssa8p from the evolutionary distant yeast Yarrowia lipolytica to perform Hsp70-dependent tasks when expressed as the sole Hsp70 for S. cerevisiae in vivo. We show that Hsp70 isoforms (i supported yeast viability yet with markedly different growth rates, (ii influenced the propagation and stability of the [PSI(+] and [URE3] prions, but iii did not significantly affect the proteasomal degradation rate of CFTR. Additionally, we show that individual Hsp70 orthologs did not induce the formation of different prion strains, but rather influenced the aggregation properties of Sup35 in vivo. Finally, we show that [URE3] curing by the overexpression of Ydj1p is Hsp70-isoform dependent.Despite very high homology and overlapping functions, the different Hsp70 orthologs have evolved to possess distinct activities that are required to cope with different types of substrates or stress situations. Yeast prions provide a very sensitive model to uncover this functional specialization and to explore the intricate network of chaperone/co-chaperone/substrates interactions.

  10. Elimination of glycerol production in anaerobic cultures of a Saccharomyces cerevisiae strain engineered to use acetic acid as an electron acceptor.

    Guadalupe Medina, Víctor; Almering, Marinka J H; van Maris, Antonius J A; Pronk, Jack T

    2010-01-01

    In anaerobic cultures of wild-type Saccharomyces cerevisiae, glycerol production is essential to reoxidize NADH produced in biosynthetic processes. Consequently, glycerol is a major by-product during anaerobic production of ethanol by S. cerevisiae, the single largest fermentation process in industrial biotechnology. The present study investigates the possibility of completely eliminating glycerol production by engineering S. cerevisiae such that it can reoxidize NADH by the reduction of acetic acid to ethanol via NADH-dependent reactions. Acetic acid is available at significant amounts in lignocellulosic hydrolysates of agricultural residues. Consistent with earlier studies, deletion of the two genes encoding NAD-dependent glycerol-3-phosphate dehydrogenase (GPD1 and GPD2) led to elimination of glycerol production and an inability to grow anaerobically. However, when the E. coli mhpF gene, encoding the acetylating NAD-dependent acetaldehyde dehydrogenase (EC 1.2.1.10; acetaldehyde+NAD++coenzyme Aacetyl coenzyme A+NADH+H+), was expressed in the gpd1Delta gpd2Delta strain, anaerobic growth was restored by supplementation with 2.0 g liter(-1) acetic acid. The stoichiometry of acetate consumption and growth was consistent with the complete replacement of glycerol formation by acetate reduction to ethanol as the mechanism for NADH reoxidation. This study provides a proof of principle for the potential of this metabolic engineering strategy to improve ethanol yields, eliminate glycerol production, and partially convert acetate, which is a well-known inhibitor of yeast performance in lignocellulosic hydrolysates, to ethanol. Further research should address the kinetic aspects of acetate reduction and the effect of the elimination of glycerol production on cellular robustness (e.g., osmotolerance).

  11. Wearable Wide-Range Strain Sensors Based on Ionic Liquids and Monitoring of Human Activities

    Shao-Hui Zhang

    2017-11-01

    Full Text Available Wearable sensors for detection of human activities have encouraged the development of highly elastic sensors. In particular, to capture subtle and large-scale body motion, stretchable and wide-range strain sensors are highly desired, but still a challenge. Herein, a highly stretchable and transparent stain sensor based on ionic liquids and elastic polymer has been developed. The as-obtained sensor exhibits impressive stretchability with wide-range strain (from 0.1% to 400%, good bending properties and high sensitivity, whose gauge factor can reach 7.9. Importantly, the sensors show excellent biological compatibility and succeed in monitoring the diverse human activities ranging from the complex large-scale multidimensional motions to subtle signals, including wrist, finger and elbow joint bending, finger touch, breath, speech, swallow behavior and pulse wave.

  12. Enhancement of ethanol production from green liquor-ethanol-pretreated sugarcane bagasse by glucose-xylose cofermentation at high solid loadings with mixed Saccharomyces cerevisiae strains.

    You, Yanzhi; Li, Pengfei; Lei, Fuhou; Xing, Yang; Jiang, Jianxin

    2017-01-01

    Efficient cofermentation of glucose and xylose is necessary for economically feasible bioethanol production from lignocellulosic biomass. Here, we demonstrate pretreatment of sugarcane bagasse (SCB) with green liquor (GL) combined with ethanol (GL-Ethanol) by adding different GL amounts. The common Saccharomyces cerevisiae (CSC) and thermophilic S. cerevisiae (TSC) strains were used and different yeast cell mass ratios (CSC to TSC) were compared. The simultaneous saccharification and cofermentation (SSF/SSCF) process was performed by 5-20% (w/v) dry substrate (DS) solid loadings to determine optimal conditions for the co-consumption of glucose and xylose. Compared to previous studies that tested fermentation of glucose using only the CSC, we obtained higher ethanol yield and concentration (92.80% and 23.22 g/L) with 1.5 mL GL/g-DS GL-Ethanol-pretreated SCB at 5% (w/v) solid loading and a CSC-to-TSC yeast cell mass ratio of 1:2 (w/w). Using 10% (w/v) solid loading under the same conditions, the ethanol concentration increased to 42.53 g/L but the ethanol yield decreased to 84.99%. In addition, an increase in the solid loading up to a certain point led to an increase in the ethanol concentration from 1.5 mL GL/g-DS-pretreated SCB. The highest ethanol concentration (68.24 g/L) was obtained with 15% (w/v) solid loading, using a CSC-to-TSC yeast cell mass ratio of 1:3 (w/w). GL-Ethanol pretreatment is a promising pretreatment method for improving both glucan and xylan conversion efficiencies of SCB. There was a competitive relationship between the two yeast strains, and the glucose and xylose utilization ability of the TSC was better than that of the CSC. Ethanol concentration was obviously increased at high solid loading, but the yield decreased as a result of an increase in the viscosity and inhibitor levels in the fermentation system. Finally, the SSCF of GL-Ethanol-pretreated SCB with mixed S. cerevisiae strains increased ethanol concentration and was an

  13. Systematic strain construction and process development: Xylitol production by Saccharomyces cerevisiae expressing Candida tenuis xylose reductase in wild-type or mutant form.

    Pratter, S M; Eixelsberger, T; Nidetzky, B

    2015-12-01

    A novel Saccharomyces cerevisiae whole-cell biocatalyst for xylitol production based on Candida tenuis xylose reductase (CtXR) is presented. Six recombinant strains expressing wild-type CtXR or an NADH-specific mutant were constructed and evaluated regarding effects of expression mode, promoter strength, biocatalyst concentration and medium composition. Intracellular XR activities ranged from 0.09 U mgProt(-1) to 1.05 U mgProt(-1) but did not correlate with the strains' xylitol productivities, indicating that other factors limited xylose conversion in the high-activity strains. The CtXR mutant decreased the biocatalyst's performance, suggesting use of the NADPH-preferring wild-type enzyme when (semi-)aerobic conditions are applied. In a bioreactor process, the best-performing strain converted 40 g L(-1) xylose with an initial productivity of 1.16 g L(-1)h(-1) and a xylitol yield of 100%. The obtained results underline the potential of CtXR wild-type for xylose reduction and point out parameters to improve "green" xylitol production. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Metabolic and transcriptomic response of the wine yeast Saccharomyces cerevisiae strain EC1118 after an oxygen impulse under carbon-sufficient, nitrogen-limited fermentative conditions.

    Orellana, Marcelo; Aceituno, Felipe F; Slater, Alex W; Almonacid, Leonardo I; Melo, Francisco; Agosin, Eduardo

    2014-05-01

    During alcoholic fermentation, Saccharomyces cerevisiae is exposed to continuously changing environmental conditions, such as decreasing sugar and increasing ethanol concentrations. Oxygen, a critical nutrient to avoid stuck and sluggish fermentations, is only discretely available throughout the process after pump-over operation. In this work, we studied the physiological response of the wine yeast S. cerevisiae strain EC1118 to a sudden increase in dissolved oxygen, simulating pump-over operation. With this aim, an impulse of dissolved oxygen was added to carbon-sufficient, nitrogen-limited anaerobic continuous cultures. Results showed that genes related to mitochondrial respiration, ergosterol biosynthesis, and oxidative stress, among other metabolic pathways, were induced after the oxygen impulse. On the other hand, mannoprotein coding genes were repressed. The changes in the expression of these genes are coordinated responses that share common elements at the level of transcriptional regulation. Beneficial and detrimental effects of these physiological processes on wine quality highlight the dual role of oxygen in 'making or breaking wines'. These findings will facilitate the development of oxygen addition strategies to optimize yeast performance in industrial fermentations. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  15. Evidence that a recombinationless strain, rad 51, of Saccharomyces cerevisiae lacks the budding cell resistance to γ-rays

    Hama-Inaba, Hiroko; Saeki, Tetsuya

    1975-01-01

    The radiosensitivities of a wild-type and x-ray sensitive mutant, rad 51 (defective in genetic recombination) of Saccharomyces cerevisiae to γ-rays were compared, using non-synchronized and partially synchronized cultures. The rad 51 cells, either haploid or diploid, showed only very small changes in radiosensitivity during cell growth, whereas the wild-type cells, especially haploid, showed the well-known budding resistance. The heterozygous (wild/rad 51) diploid cells showed in a survival curve a remarkable budding resistance and sigmoidal inactivation kinetics similar to those of wild-type homozygous diploid cells. (author)

  16. The compressive behaviour and constitutive equation of polyimide foam in wide strain rate and temperature

    Yoshimoto Akifumi

    2015-01-01

    Full Text Available These days, polymer foams, such as polyurethane foam and polystyrene foam, are used in various situations as a thermal insulator or shock absorber. In general, however, their strength is insufficient in high temperature environments because of their low glass transition temperature. Polyimide is a polymer which has a higher glass transition temperature and high strength. Its mechanical properties do not vary greatly, even in low temperature environments. Therefore, polyimide foam is expected to be used in the aerospace industry. Thus, the constitutive equation of polyimide foam that can be applied across a wide range of strain rates and ambient temperature is very useful. In this study, a series of compression tests at various strain rates, from 10−3 to 103 s−1 were carried out in order to examine the effect of strain rate on the compressive properties of polyimide foam. The flow stress of polyimide foam increased rapidly at dynamic strain rates. The effect of ambient temperature on the properties of polyimide foam was also investigated at temperature from − 190 °C to 270°∘C. The flow stress decreased with increasing temperature.

  17. Osmotolerance and leavening ability in sweet and frozen sweet dough. Comparative analysis between Torulaspora delbrueckii and Saccharomyces cerevisiae baker's yeast strains.

    Hernandez-Lopez, M J; Prieto, J A; Randez-Gil, F

    2003-01-01

    The response of Saccharomyces cerevisiae and freeze-tolerant Torulaspora delbrueckii strains to osmotic stress and their CO2 production capacity in sweet and frozen-sweet dough has been examined. T. delbrueckii strains, IGC5321 and IGC5323 showed higher leavening ability than Saccharomyces, specially after exposure to hyperosmotic stress of bread dough containing 20% sucrose and 2% salt added. In addition, Torulaspora and especially T. delbrueckii IGC5321 exhibited no loss of CO2 production capacity during freeze-thaw stress. Overall, these results appeared to indicate that Torulaspora cells are more tolerant than Saccharomyces to osmotic stress of bread dough. This trait correlated with a low invertase activity, a slow rate of trehalose mobilisation and the ability to respond rapidly to osmotic stress. Growth behaviour on high osmotic synthetic media was also examined. Cells of the IGC5321 strain showed intrinsic osmotolerance and ion toxicity resistance. However, T. delbrueckii IGC5323 exhibited a clear phenotype of osmosensitivity. Hence, this characteristic may not be essential or the only determinant for leavening ability in salted high-sugar dough.

  18. Ethanol production and maximum cell growth are highly correlated with membrane lipid composition during fermentation as determined by lipidomic analysis of 22 Saccharomyces cerevisiae strains.

    Henderson, Clark M; Lozada-Contreras, Michelle; Jiranek, Vladimir; Longo, Marjorie L; Block, David E

    2013-01-01

    Optimizing ethanol yield during fermentation is important for efficient production of fuel alcohol, as well as wine and other alcoholic beverages. However, increasing ethanol concentrations during fermentation can create problems that result in arrested or sluggish sugar-to-ethanol conversion. The fundamental cellular basis for these problem fermentations, however, is not well understood. Small-scale fermentations were performed in a synthetic grape must using 22 industrial Saccharomyces cerevisiae strains (primarily wine strains) with various degrees of ethanol tolerance to assess the correlation between lipid composition and fermentation kinetic parameters. Lipids were extracted at several fermentation time points representing different growth phases of the yeast to quantitatively analyze phospholipids and ergosterol utilizing atmospheric pressure ionization-mass spectrometry methods. Lipid profiling of individual fermentations indicated that yeast lipid class profiles do not shift dramatically in composition over the course of fermentation. Multivariate statistical analysis of the data was performed using partial least-squares linear regression modeling to correlate lipid composition data with fermentation kinetic data. The results indicate a strong correlation (R(2) = 0.91) between the overall lipid composition and the final ethanol concentration (wt/wt), an indicator of strain ethanol tolerance. One potential component of ethanol tolerance, the maximum yeast cell concentration, was also found to be a strong function of lipid composition (R(2) = 0.97). Specifically, strains unable to complete fermentation were associated with high phosphatidylinositol levels early in fermentation. Yeast strains that achieved the highest cell densities and ethanol concentrations were positively correlated with phosphatidylcholine species similar to those known to decrease the perturbing effects of ethanol in model membrane systems.

  19. Global mRNA expression analysis in myosin II deficient strains of Saccharomyces cerevisiae reveals an impairment of cell integrity functions

    Rivera-Molina Félix E

    2008-01-01

    Full Text Available Abstract Background The Saccharomyces cerevisiae MYO1 gene encodes the myosin II heavy chain (Myo1p, a protein required for normal cytokinesis in budding yeast. Myo1p deficiency in yeast (myo1Δ causes a cell separation defect characterized by the formation of attached cells, yet it also causes abnormal budding patterns, formation of enlarged and elongated cells, increased osmotic sensitivity, delocalized chitin deposition, increased chitin synthesis, and hypersensitivity to the chitin synthase III inhibitor Nikkomycin Z. To determine how differential expression of genes is related to these diverse cell wall phenotypes, we analyzed the global mRNA expression profile of myo1Δ strains. Results Global mRNA expression profiles of myo1Δ strains and their corresponding wild type controls were obtained by hybridization to yeast oligonucleotide microarrays. Results for selected genes were confirmed by real time RT-PCR. A total of 547 differentially expressed genes (p ≤ 0.01 were identified with 263 up regulated and 284 down regulated genes in the myo1Δ strains. Gene set enrichment analysis revealed the significant over-representation of genes in the protein biosynthesis and stress response categories. The SLT2/MPK1 gene was up regulated in the microarray, and a myo1Δslt2Δ double mutant was non-viable. Overexpression of ribosomal protein genes RPL30 and RPS31 suppressed the hypersensitivity to Nikkomycin Z and increased the levels of phosphorylated Slt2p in myo1Δ strains. Increased levels of phosphorylated Slt2p were also observed in wild type strains under these conditions. Conclusion Following this analysis of global mRNA expression in yeast myo1Δ strains, we conclude that 547 genes were differentially regulated in myo1Δ strains and that the stress response and protein biosynthesis gene categories were coordinately regulated in this mutant. The SLT2/MPK1 gene was confirmed to be essential for myo1Δ strain viability, supporting that the up

  20. Genome-wide screen in Saccharomyces cerevisiae identifies vacuolar protein sorting, autophagy, biosynthetic, and tRNA methylation genes involved in life span regulation.

    Paola Fabrizio

    2010-07-01

    Full Text Available The study of the chronological life span of Saccharomyces cerevisiae, which measures the survival of populations of non-dividing yeast, has resulted in the identification of homologous genes and pathways that promote aging in organisms ranging from yeast to mammals. Using a competitive genome-wide approach, we performed a screen of a complete set of approximately 4,800 viable deletion mutants to identify genes that either increase or decrease chronological life span. Half of the putative short-/long-lived mutants retested from the primary screen were confirmed, demonstrating the utility of our approach. Deletion of genes involved in vacuolar protein sorting, autophagy, and mitochondrial function shortened life span, confirming that respiration and degradation processes are essential for long-term survival. Among the genes whose deletion significantly extended life span are ACB1, CKA2, and TRM9, implicated in fatty acid transport and biosynthesis, cell signaling, and tRNA methylation, respectively. Deletion of these genes conferred heat-shock resistance, supporting the link between life span extension and cellular protection observed in several model organisms. The high degree of conservation of these novel yeast longevity determinants in other species raises the possibility that their role in senescence might be conserved.

  1. Genome-wide screen in Saccharomyces cerevisiae identifies vacuolar protein sorting, autophagy, biosynthetic, and tRNA methylation genes involved in life span regulation.

    Fabrizio, Paola; Hoon, Shawn; Shamalnasab, Mehrnaz; Galbani, Abdulaye; Wei, Min; Giaever, Guri; Nislow, Corey; Longo, Valter D

    2010-07-15

    The study of the chronological life span of Saccharomyces cerevisiae, which measures the survival of populations of non-dividing yeast, has resulted in the identification of homologous genes and pathways that promote aging in organisms ranging from yeast to mammals. Using a competitive genome-wide approach, we performed a screen of a complete set of approximately 4,800 viable deletion mutants to identify genes that either increase or decrease chronological life span. Half of the putative short-/long-lived mutants retested from the primary screen were confirmed, demonstrating the utility of our approach. Deletion of genes involved in vacuolar protein sorting, autophagy, and mitochondrial function shortened life span, confirming that respiration and degradation processes are essential for long-term survival. Among the genes whose deletion significantly extended life span are ACB1, CKA2, and TRM9, implicated in fatty acid transport and biosynthesis, cell signaling, and tRNA methylation, respectively. Deletion of these genes conferred heat-shock resistance, supporting the link between life span extension and cellular protection observed in several model organisms. The high degree of conservation of these novel yeast longevity determinants in other species raises the possibility that their role in senescence might be conserved.

  2. Genome-wide study of the adaptation of Saccharomyces cerevisiae to the early stages of wine fermentation.

    Novo, Maite; Mangado, Ana; Quirós, Manuel; Morales, Pilar; Salvadó, Zoel; Gonzalez, Ramon

    2013-01-01

    This work was designed to identify yeast cellular functions specifically affected by the stress factors predominating during the early stages of wine fermentation, and genes required for optimal growth under these conditions. The main experimental method was quantitative fitness analysis by means of competition experiments in continuous culture of whole genome barcoded yeast knockout collections. This methodology allowed the identification of haploinsufficient genes, and homozygous deletions resulting in growth impairment in synthetic must. However, genes identified as haploproficient, or homozygous deletions resulting in fitness advantage, were of little predictive power concerning optimal growth in this medium. The relevance of these functions for enological performance of yeast was assessed in batch cultures with single strains. Previous studies addressing yeast adaptation to winemaking conditions by quantitative fitness analysis were not specifically focused on the proliferative stages. In some instances our results highlight the importance of genes not previously linked to winemaking. In other cases they are complementary to those reported in previous studies concerning, for example, the relevance of some genes involved in vacuolar, peroxisomal, or ribosomal functions. Our results indicate that adaptation to the quickly changing growth conditions during grape must fermentation require the function of different gene sets in different moments of the process. Transport processes and glucose signaling seem to be negatively affected by the stress factors encountered by yeast in synthetic must. Vacuolar activity is important for continued growth during the transition to stationary phase. Finally, reduced biogenesis of peroxisomes also seems to be advantageous. However, in contrast to what was described for later stages, reduced protein synthesis is not advantageous for the early (proliferative) stages of the fermentation process. Finally, we found adenine and lysine

  3. Genome-wide screening of the genes required for tolerance to vanillin, which is a potential inhibitor of bioethanol fermentation, in Saccharomyces cerevisiae.

    Endo, Ayako; Nakamura, Toshihide; Ando, Akira; Tokuyasu, Ken; Shima, Jun

    2008-04-15

    Lignocellulosic materials are abundant and among the most important potential sources for bioethanol production. Although the pretreatment of lignocellulose is necessary for efficient saccharification and fermentation, numerous by-products, including furan derivatives, weak acids, and phenolic compounds, are generated in the pretreatment step. Many of these components inhibit the growth and fermentation of yeast. In particular, vanillin is one of the most effective inhibitors in lignocellulose hydrolysates because it inhibits fermentation at very low concentrations. To identify the genes required for tolerance to vanillin, we screened a set of diploid yeast deletion mutants, which are powerful tools for clarifying the function of particular genes. Seventy-six deletion mutants were identified as vanillin-sensitive mutants. The numerous deleted genes in the vanillin-sensitive mutants were classified under the functional categories for 'chromatin remodeling' and 'vesicle transport', suggesting that these functions are important for vanillin tolerance. The cross-sensitivity of the vanillin-sensitive mutants to furan derivatives, weak acids, and phenolic compounds was also examined. Genes for ergosterol biosynthesis were required for tolerance to all inhibitory compounds tested, suggesting that ergosterol is a key component of tolerance to various inhibitors. Our analysis predicts that vanillin tolerance in Saccharomyces cerevisiae is affected by various complicated processes that take place on both the molecular and the cellular level. In addition, the ergosterol biosynthetic process is important for achieving a tolerance to various inhibitors. Our findings provide a biotechnological basis for the molecular engineering as well as for screening of more robust yeast strains that may potentially be useful in bioethanol fermentation.

  4. Genome-wide screening of the genes required for tolerance to vanillin, which is a potential inhibitor of bioethanol fermentation, in Saccharomyces cerevisiae

    Tokuyasu Ken

    2008-04-01

    Full Text Available Abstract Background Lignocellulosic materials are abundant and among the most important potential sources for bioethanol production. Although the pretreatment of lignocellulose is necessary for efficient saccharification and fermentation, numerous by-products, including furan derivatives, weak acids, and phenolic compounds, are generated in the pretreatment step. Many of these components inhibit the growth and fermentation of yeast. In particular, vanillin is one of the most effective inhibitors in lignocellulose hydrolysates because it inhibits fermentation at very low concentrations. To identify the genes required for tolerance to vanillin, we screened a set of diploid yeast deletion mutants, which are powerful tools for clarifying the function of particular genes. Results Seventy-six deletion mutants were identified as vanillin-sensitive mutants. The numerous deleted genes in the vanillin-sensitive mutants were classified under the functional categories for 'chromatin remodeling' and 'vesicle transport', suggesting that these functions are important for vanillin tolerance. The cross-sensitivity of the vanillin-sensitive mutants to furan derivatives, weak acids, and phenolic compounds was also examined. Genes for ergosterol biosynthesis were required for tolerance to all inhibitory compounds tested, suggesting that ergosterol is a key component of tolerance to various inhibitors. Conclusion Our analysis predicts that vanillin tolerance in Saccharomyces cerevisiae is affected by various complicated processes that take place on both the molecular and the cellular level. In addition, the ergosterol biosynthetic process is important for achieving a tolerance to various inhibitors. Our findings provide a biotechnological basis for the molecular engineering as well as for screening of more robust yeast strains that may potentially be useful in bioethanol fermentation.

  5. A novel wild-type Saccharomyces cerevisiae strain TSH1 in scaling-up of solid-state fermentation of ethanol from sweet sorghum stalks.

    Ran Du

    Full Text Available The rising demand for bioethanol, the most common alternative to petroleum-derived fuel used worldwide, has encouraged a feedstock shift to non-food crops to reduce the competition for resources between food and energy production. Sweet sorghum has become one of the most promising non-food energy crops because of its high output and strong adaptive ability. However, the means by which sweet sorghum stalks can be cost-effectively utilized for ethanol fermentation in large-scale industrial production and commercialization remains unclear. In this study, we identified a novel Saccharomyces cerevisiae strain, TSH1, from the soil in which sweet sorghum stalks were stored. This strain exhibited excellent ethanol fermentative capacity and ability to withstand stressful solid-state fermentation conditions. Furthermore, we gradually scaled up from a 500-mL flask to a 127-m3 rotary-drum fermenter and eventually constructed a 550-m3 rotary-drum fermentation system to establish an efficient industrial fermentation platform based on TSH1. The batch fermentations were completed in less than 20 hours, with up to 96 tons of crushed sweet sorghum stalks in the 550-m3 fermenter reaching 88% of relative theoretical ethanol yield (RTEY. These results collectively demonstrate that ethanol solid-state fermentation technology can be a highly efficient and low-cost solution for utilizing sweet sorghum, providing a feasible and economical means of developing non-food bioethanol.

  6. A novel wild-type Saccharomyces cerevisiae strain TSH1 in scaling-up of solid-state fermentation of ethanol from sweet sorghum stalks.

    Du, Ran; Yan, Jianbin; Feng, Quanzhou; Li, Peipei; Zhang, Lei; Chang, Sandra; Li, Shizhong

    2014-01-01

    The rising demand for bioethanol, the most common alternative to petroleum-derived fuel used worldwide, has encouraged a feedstock shift to non-food crops to reduce the competition for resources between food and energy production. Sweet sorghum has become one of the most promising non-food energy crops because of its high output and strong adaptive ability. However, the means by which sweet sorghum stalks can be cost-effectively utilized for ethanol fermentation in large-scale industrial production and commercialization remains unclear. In this study, we identified a novel Saccharomyces cerevisiae strain, TSH1, from the soil in which sweet sorghum stalks were stored. This strain exhibited excellent ethanol fermentative capacity and ability to withstand stressful solid-state fermentation conditions. Furthermore, we gradually scaled up from a 500-mL flask to a 127-m3 rotary-drum fermenter and eventually constructed a 550-m3 rotary-drum fermentation system to establish an efficient industrial fermentation platform based on TSH1. The batch fermentations were completed in less than 20 hours, with up to 96 tons of crushed sweet sorghum stalks in the 550-m3 fermenter reaching 88% of relative theoretical ethanol yield (RTEY). These results collectively demonstrate that ethanol solid-state fermentation technology can be a highly efficient and low-cost solution for utilizing sweet sorghum, providing a feasible and economical means of developing non-food bioethanol.

  7. Effect of selected Saccharomyces cerevisiae yeast strains and different aging techniques on the polysaccharide and polyphenolic composition and sensorial characteristics of Cabernet Sauvignon red wines.

    del Barrio-Galán, Rubén; Cáceres-Mella, Alejandro; Medel-Marabolí, Marcela; Peña-Neira, Álvaro

    2015-08-15

    The objective of this work was to study the effect of two Saccharomyces cerevisiae yeast strains with different capabilities of polysaccharide liberation during alcoholic fermentation in addition to subsequent aging on lees with or without oak wood chips as well as aging with commercial inactive dry yeast on the physical, chemical and sensorial characteristics of Cabernet Sauvignon red wines. The HPS (high levels of polysaccharides) yeast strain released higher amounts of polysaccharides (429 g L(-1)) than EC1118 (390 g L(-1)) during alcoholic fermentation, but the concentration equalized during the aging period (424 and 417 g L(-1) respectively). All aging techniques increased the polysaccharide concentration, but the increase was dependent on the technique applied. A higher liberation of polysaccharides reduced the concentration of most of the phenolic families analyzed. Moreover, no clear effect of the different aging techniques used in this study on color stabilization was found. The HPS wines were better valued than the EC1118 wines by the panel of tasters after alcoholic fermentation. In general, the HPS wines showed better physicochemical and sensorial characteristics than the EC1118 wines. According to the results obtained during the aging period, all aging techniques contributed to improve wine quality, but it was difficult to establish the technique that allowed the best wine to be obtained, because it depended on the aging technique used and the period of aging. © 2014 Society of Chemical Industry.

  8. Saccharomyces cerevisiae

    Bojsen, Rasmus K; Andersen, Kaj Scherz; Regenberg, Birgitte

    2012-01-01

    Microbial biofilms can be defined as multi-cellular aggregates adhering to a surface and embedded in an extracellular matrix (ECM). The nonpathogenic yeast, Saccharomyces cerevisiae, follows the common traits of microbial biofilms with cell-cell and cell-surface adhesion. S. cerevisiae is shown t...

  9. A strain of Saccharomyces cerevisiae evolved for fermentation of lignocellulosic biomass displays improved growth and fermentative ability in high solids concentrations and in the presence of inhibitory compounds

    Hawkins Gary M

    2011-11-01

    Full Text Available Abstract Background Softwoods are the dominant source of lignocellulosic biomass in the northern hemisphere, and have been investigated worldwide as a renewable substrate for cellulosic ethanol production. One challenge to using softwoods, which is particularly acute with pine, is that the pretreatment process produces inhibitory compounds detrimental to the growth and metabolic activity of fermenting organisms. To overcome the challenge of bioconversion in the presence of inhibitory compounds, especially at high solids loading, a strain of Saccharomyces cerevisiae was subjected to evolutionary engineering and adaptation for fermentation of pretreated pine wood (Pinus taeda. Results An industrial strain of Saccharomyces, XR122N, was evolved using pretreated pine; the resulting daughter strain, AJP50, produced ethanol much more rapidly than its parent in fermentations of pretreated pine. Adaptation, by preculturing of the industrial yeast XR122N and the evolved strains in 7% dry weight per volume (w/v pretreated pine solids prior to inoculation into higher solids concentrations, improved fermentation performance of all strains compared with direct inoculation into high solids. Growth comparisons between XR122N and AJP50 in model hydrolysate media containing inhibitory compounds found in pretreated biomass showed that AJP50 exited lag phase faster under all conditions tested. This was due, in part, to the ability of AJP50 to rapidly convert furfural and hydroxymethylfurfural to their less toxic alcohol derivatives, and to recover from reactive oxygen species damage more quickly than XR122N. Under industrially relevant conditions of 17.5% w/v pretreated pine solids loading, additional evolutionary engineering was required to decrease the pronounced lag phase. Using a combination of adaptation by inoculation first into a solids loading of 7% w/v for 24 hours, followed by a 10% v/v inoculum (approximately equivalent to 1 g/L dry cell weight into 17

  10. Production of fermentation aroma compounds by Saccharomyces cerevisiae wine yeasts: effects of yeast assimilable nitrogen on two model strains.

    Carrau, Francisco M; Medina, Karina; Farina, Laura; Boido, Eduardo; Henschke, Paul A; Dellacassa, Eduardo

    2008-11-01

    The contribution of yeast fermentation metabolites to the aromatic profile of wine is well documented; however, the biotechnological application of this knowledge, apart from strain selection, is still rather limited and often contradictory. Understanding and modeling the relationship between nutrient availability and the production of desirable aroma compounds by different strains must be one of the main objectives in the selection of industrial yeasts for the beverage and food industry. In order to overcome the variability in the composition of grape juices, we have used a chemically defined model medium for studying yeast physiological behavior and metabolite production in response to nitrogen supplementation so as to identify an appropriate yeast assimilable nitrogen level for strain differentiation. At low initial nitrogen concentrations, strain KU1 produced higher quantities of esters and fatty acids whereas M522 produced higher concentrations of isoacids, gamma-butyrolactone, higher alcohols and 3-methylthio-1-propanol. We propose that although strains KU1 and M522 have a similar nitrogen consumption profile, they represent useful models for the chemical characterization of wine strains in relation to wine quality. The differential production of aroma compounds by the two strains is discussed in relation to their capacity for nitrogen usage and their impact on winemaking. The results obtained here will help to develop targeted metabolic footprinting methods for the discrimination of industrial yeasts.

  11. Flocculation in ale brewing strains of Saccharomyces cerevisiae: re-evaluation of the role of cell surface charge and hydrophobicity.

    Holle, Ann Van; Machado, Manuela D; Soares, Eduardo V

    2012-02-01

    Flocculation is an eco-friendly process of cell separation, which has been traditionally exploited by the brewing industry. Cell surface charge (CSC), cell surface hydrophobicity (CSH) and the presence of active flocculins, during the growth of two (NCYC 1195 and NCYC 1214) ale brewing flocculent strains, belonging to the NewFlo phenotype, were examined. Ale strains, in exponential phase of growth, were not flocculent and did not present active flocculent lectins on the cell surface; in contrast, the same strains, in stationary phase of growth, were highly flocculent (>98%) and presented a hydrophobicity of approximately three to seven times higher than in exponential phase. No relationship between growth phase, flocculation and CSC was observed. For comparative purposes, a constitutively flocculent strain (S646-1B) and its isogenic non-flocculent strain (S646-8D) were also used. The treatment of ale brewing and S646-1B strains with pronase E originated a loss of flocculation and a strong reduction of CSH; S646-1B pronase E-treated cells displayed a similar CSH as the non-treated S646-8D cells. The treatment of the S646-8D strain with protease did not reduce CSH. In conclusion, the increase of CSH observed at the onset of flocculation of ale strains is a consequence of the presence of flocculins on the yeast cell surface and not the cause of yeast flocculation. CSH and CSC play a minor role in the auto-aggregation of the ale strains since the degree of flocculation is defined, primarily, by the presence of active flocculins on the yeast cell wall.

  12. Isolation of a high malic and low acetic acid-producing sake yeast Saccharomyces cerevisiae strain screened from respiratory inhibitor 2,4-dinitrophenol (DNP)-resistant strains.

    Kosugi, Shingo; Kiyoshi, Keiji; Oba, Takahiro; Kusumoto, Kenichi; Kadokura, Toshimori; Nakazato, Atsumi; Nakayama, Shunichi

    2014-01-01

    We isolated 2,4-dinitrophenol (DNP)-resistant sake yeast strains by UV mutagenesis. Among the DNP-resistant mutants, we focused on strains exhibiting high malic acid and low acetic acid production. The improved organic acid composition is unlikely to be under the control of enzyme activities related to malic and acetic acid synthesis pathways. Instead, low mitochondrial activity was observed in DNP-resistant mutants, indicating that the excess pyruvic acid generated during glycolysis is not metabolized in the mitochondria but converted to malic acid in the cytosol. In addition, the NADH/NAD(+) ratio of the DNP-resistant strains was higher than that of the parental strain K901. These results suggest that the increased NADH/NAD(+) ratio together with the low mitochondrial activity alter the organic acid composition because malic acid synthesis requires NADH, while acetic acid uses NAD(+). Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  13. Analysis of the secondary compounds produced by Saccharomyces cerevisiae and wild yeast strains during the production of "cachaça" Análise dos componentes secundários produzidos por Saccharomyces cerevisiae e leveduras selvagens durante a produção de cachaça

    Maria Cecília Fachine Dato

    2005-03-01

    Full Text Available The aim of this study is to compare the composition of "cachaças" produced in 10 fermentation cycles by Saccharomyces cerevisiae (Sc and wild yeast strains [Pichia silvicola (Ps, Pichia anomala 1 (Pa1, Pichia anomala 2 (Pa2 and Dekkera bruxelensis (Db], isolated from distilleries in Jaboticabal - SP, Brazil. The secondary components of the heart fraction were determined by gas chromatography. The levels of secondary components were influenced by the wine pH, which varied among yeast strains. S. cerevisiae showed slightly more secondary components, whereas wild strains produced more higher alcohols. Wild yeast strains were shown to be adequate for the production of a high quality "cachaça".O presente trabalho visou estabelecer uma comparação entre composição de cachaças produzidas por Saccharomyces cerevisiae (Sc e estirpes de leveduras selvagens [Pichia silvicola (Ps, Pichia anomala 1 (Pa1, Pichia anomala 2 (Pa2 e Dekkera bruxelensis (Db], isoladas em destilarias da região de Jaboticabal-SP. Os componentes secundários da fração denominada coração foram determinados por cromatografia gasosa. Os níveis dos componentes secundários foram influenciados pelo pH dos respectivos vinhos, os quais dependem da estirpe de levedura empregada no processo fermentativo. A Saccharomyces cerevisiae apresentou valores ligeiramente superiores de componentes secundários, enquanto as estirpes selvagens produziram maiores teores de álcoois superiores. As estirpes selvagens de leveduras mostraram-se adequadas para obtenção de uma cachaça de boa qualidade.

  14. A flexible piezoresistive carbon black network in silicone rubber for wide range deformation and strain sensing

    Zhu, Jianxiong; Wang, Hai; Zhu, Yali

    2018-01-01

    This work presents the design, fabrication, and measurement of a piezoresistive device with a carbon black (CB) particle network in a highly flexible silicone rubber for large deformation and wide range strain sensing. The piezoresistive composite film was fabricated with a mixture of silicone rubber and CB filler particles. The test results showed that the CB particle network in the silicone rubber strongly affected the resistance of the device during the process of drawing and its recovery. We found that the 50% volume ratio of CB filler particles showed a lower relative resistance than the 33.3% volume ratio of CB filler particles, but with an advantage of good resistance recovery stability and a smaller perturbation error (smaller changed resistance) during the periodic back and forth linear motor test. With both having a 50% volume ratio of CB filler particles and a 33.3% volume ratio of CB filler particles, one can reach up to 200% strain with resistances 18 kΩ and 110 kΩ, respectively. We also found that the relative resistance increased in an approximately linear relationship corresponding to the value of step-increased instantaneous length for the reported device. Moreover, an application test through hand drawing was used to demonstrate the piezoresistive performance of the device, which showed that the reported device was capable of measuring the instantaneous length with large deformation.

  15. The mechanical behavior of metal alloys with grain size distribution in a wide range of strain rates

    Skripnyak, V. A.; Skripnyak, V. V.; Skripnyak, E. G.

    2017-12-01

    The paper discusses a multiscale simulation approach for the construction of grain structure of metals and alloys, providing high tensile strength with ductility. This work compares the mechanical behavior of light alloys and the influence of the grain size distribution in a wide range of strain rates. The influence of the grain size distribution on the inelastic deformation and fracture of aluminium and magnesium alloys is investigated by computer simulations in a wide range of strain rates. It is shown that the yield stress depends on the logarithm of the normalized strain rate for light alloys with a bimodal grain distribution and coarse-grained structure.

  16. Linking Genotype and Phenotype of Saccharomyces cerevisiae Strains Reveals Metabolic Engineering Targets and Leads to Triterpene Hyper-Producers

    Madsen, Karina Marie; Udatha, Gupta D. B. R. K.; Semba, Saori

    2011-01-01

    with the S288C strain, we implemented a strategy for the construction of a beta-amyrin production platform. The genes Erg8, Erg9 and HFA1 contained non-silent SNPs that were computationally analyzed to evaluate the changes that cause in the respective protein structures. Subsequently, Erg8, Erg9 and HFA1...

  17. Different response to acetic acid stress in Saccharomyces cerevisiae wild-type and l-ascorbic acid-producing strains.

    Martani, Francesca; Fossati, Tiziana; Posteri, Riccardo; Signori, Lorenzo; Porro, Danilo; Branduardi, Paola

    2013-09-01

    Biotechnological processes are of increasing significance for industrial production of fine and bulk chemicals, including biofuels. Unfortunately, under operative conditions microorganisms meet multiple stresses, such as non-optimal pH, temperature, oxygenation and osmotic stress. Moreover, they have to face inhibitory compounds released during the pretreatment of lignocellulosic biomasses, which constitute the preferential substrate for second-generation processes. Inhibitors include furan derivatives, phenolic compounds and weak organic acids, among which acetic acid is one of the most abundant and detrimental for cells. They impair cellular metabolism and growth, reducing the productivity of the process: therefore, the development of robust cell factories with improved production rates and resistance is of crucial importance. Here we show that a yeast strain engineered to endogenously produce vitamin C exhibits an increased tolerance compared to the parental strain when exposed to acetic acid at moderately toxic concentrations, measured as viability on plates. Starting from this evidence, we investigated more deeply: (a) the nature and levels of reactive oxygen species (ROS); (b) the activation of enzymes that act directly as detoxifiers of reactive oxygen species, such as superoxide dismutase (SOD) and catalase, in parental and engineered strains during acetic acid stress. The data indicate that the engineered strain can better recover from stress by limiting ROS accumulation, independently from SOD activation. The engineered yeast can be proposed as a model for further investigating direct and indirect mechanism(s) by which an antioxidant can rescue cells from organic acid damage; moreover, these studies will possibly provide additional targets for further strain improvements. Copyright © 2013 John Wiley & Sons, Ltd.

  18. Enhanced ethanol production, volatile compound biosynthesis and fungicide removal during growth of a newly isolated Saccharomyces cerevisiae strain on enriched pasteurized grape musts

    Sarris, Dimitris; Kotseridis, Yorgos; Galiotou-Panayotou, Maria; Papanikolaou, Seraphim [Department of Food Science and Technology, Agricultural University of Athens (Greece); Linga, Maria [Oinognosia, Wine analysis and consulting, Kiato (Greece)

    2009-02-15

    The kinetic behavior of a newly isolated Saccharomyces cerevisiae strain, grown on pasteurized grape musts enriched with industrial sugars, was studied after the addition of various concentrations [0.0 (reference), 0.4 and 2.4 mg/L] of the fungicide quinoxyfen to the medium. Batch-flask cultures were carried out. Significant quantities of biomass (10.0{+-}0.8 g/L) were produced regardless of quinoxyfen addition to the medium; therefore, the addition of the fungicide did not seriously inhibit biomass production. Ethanol was synthesized in very high quantities in all trials (highest concentrations 106.4-119.2 g/L). A slight decrease of ethanol production in terms of both absolute value and conversion yield of ethanol produced per sugar consumed was, however, observed when the quinoxyfen concentration was increased. The addition of quinoxyfen led to significantly lower ethylic ester levels, which also pertains to the acetates analyzed in this study. Fusel alcohol synthesis seemed to be activated when 0.4 mg/L quinoxyfen was added, but at 2.4 mg/L of added fungicide, no statistically significant differences were observed compared with the control trial. Volatile acid levels did not present a uniform trend in relation with the added fungicide. Finally, the fermentation was accompanied by a significant reduction of the fungicide concentration (79-82 wt% fungicide removal). (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  19. Elimination of Glycerol Production in Anaerobic Cultures of a Saccharomyces cerevisiae Strain Engineered To Use Acetic Acid as an Electron Acceptor

    Medina, V.G.; Almering, M.J.H.; Van Maris, A.J.A.; Pronk, J.T.

    2009-01-01

    In anaerobic cultures of wild-type Saccharomyces cerevisiae, glycerol production is essential to reoxidize NADH produced in biosynthetic processes. Consequently, glycerol is a major by-product during anaerobic production of ethanol by S. cerevisiae, the single largest fermentation process in

  20. L-Lactic acid production from glucose and xylose with engineered strains of Saccharomyces cerevisiae: aeration and carbon source influence yields and productivities.

    Novy, Vera; Brunner, Bernd; Nidetzky, Bernd

    2018-04-11

    Saccharomyces cerevisiae, engineered for L-lactic acid production from glucose and xylose, is a promising production host for lignocellulose-to-lactic acid processes. However, the two principal engineering strategies-pyruvate-to-lactic acid conversion with and without disruption of the competing pyruvate-to-ethanol pathway-have not yet resulted in strains that combine high lactic acid yields (Y LA ) and productivities (Q LA ) on both sugar substrates. Limitations seemingly arise from a dependency on the carbon source and the aeration conditions, but the underlying effects are poorly understood. We have recently presented two xylose-to-lactic acid converting strains, IBB14LA1 and IBB14LA1_5, which have the L-lactic acid dehydrogenase from Plasmodium falciparum (pfLDH) integrated at the pdc1 (pyruvate decarboxylase) locus. IBB14LA1_5 additionally has its pdc5 gene knocked out. In this study, the influence of carbon source and oxygen on Y LA and Q LA in IBB14LA1 and IBB14LA1_5 was investigated. In anaerobic fermentation IBB14LA1 showed a higher Y LA on xylose (0.27 g g Xyl -1 ) than on glucose (0.18 g g Glc -1 ). The ethanol yields (Y EtOH , 0.15 g g Xyl -1 and 0.32 g g Glc -1 ) followed an opposite trend. In IBB14LA1_5, the effect of the carbon source on Y LA was less pronounced (~ 0.80 g g Xyl -1 , and 0.67 g g Glc -1 ). Supply of oxygen accelerated glucose conversions significantly in IBB14LA1 (Q LA from 0.38 to 0.81 g L -1  h -1 ) and IBB14LA1_5 (Q LA from 0.05 to 1.77 g L -1  h -1 ) at constant Y LA (IBB14LA1 ~ 0.18 g g Glc -1 ; IBB14LA1_5 ~ 0.68 g g Glc -1 ). In aerobic xylose conversions, however, lactic acid production ceased completely in IBB14LA1 and decreased drastically in IBB14LA1_5 (Y LA aerobic ≤ 0.25 g g Xyl -1 and anaerobic ~ 0.80 g g Xyl -1 ) at similar Q LA (~ 0.04 g L -1  h -1 ). Switching from aerobic to microaerophilic conditions (pO 2  ~ 2%) prevented lactic acid metabolization, observed for

  1. Metabolic pathway engineering based on metabolomics confers acetic and formic acid tolerance to a recombinant xylose-fermenting strain of Saccharomyces cerevisiae

    Ishii Jun

    2011-01-01

    Full Text Available Abstract Background The development of novel yeast strains with increased tolerance toward inhibitors in lignocellulosic hydrolysates is highly desirable for the production of bio-ethanol. Weak organic acids such as acetic and formic acids are necessarily released during the pretreatment (i.e. solubilization and hydrolysis of lignocelluloses, which negatively affect microbial growth and ethanol production. However, since the mode of toxicity is complicated, genetic engineering strategies addressing yeast tolerance to weak organic acids have been rare. Thus, enhanced basic research is expected to identify target genes for improved weak acid tolerance. Results In this study, the effect of acetic acid on xylose fermentation was analyzed by examining metabolite profiles in a recombinant xylose-fermenting strain of Saccharomyces cerevisiae. Metabolome analysis revealed that metabolites involved in the non-oxidative pentose phosphate pathway (PPP [e.g. sedoheptulose-7-phosphate, ribulose-5-phosphate, ribose-5-phosphate and erythrose-4-phosphate] were significantly accumulated by the addition of acetate, indicating the possibility that acetic acid slows down the flux of the pathway. Accordingly, a gene encoding a PPP-related enzyme, transaldolase or transketolase, was overexpressed in the xylose-fermenting yeast, which successfully conferred increased ethanol productivity in the presence of acetic and formic acid. Conclusions Our metabolomic approach revealed one of the molecular events underlying the response to acetic acid and focuses attention on the non-oxidative PPP as a target for metabolic engineering. An important challenge for metabolic engineering is identification of gene targets that have material importance. This study has demonstrated that metabolomics is a powerful tool to develop rational strategies to confer tolerance to stress through genetic engineering.

  2. Effect of Agave tequilana juice on cell wall polysaccharides of three Saccharomyces cerevisiae strains from different origins.

    Aguilar-Uscanga, Blanca; Arrizon, Javier; Ramirez, Jesús; Solis-Pacheco, Josué

    2007-02-01

    In this study, a characterization of cell wall polysaccharide composition of three yeasts involved in the production of agave distilled beverages was performed. The three yeast strains were isolated from different media (tequila, mezcal and bakery) and were evaluated for the beta(1,3)-glucanase lytic activity and the beta-glucan/ mannan ratio during the fermentation of Agave tequilana juice and in YPD media (control). Fermentations were performed in shake flasks with 30 g l(-1) sugar concentration of A. tequilana juice and with the control YPD using 30 g l(-1) of glucose. The three yeasts strains showed different levels of beta-glucan and mannan when they were grown in A. tequilana juice in comparison to the YPD media. The maximum rate of cell wall lyses was 50% lower in fermentations with A. tequilana juice for yeasts isolated from tequila and mezcal than compared to the bakery yeast.

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

    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.

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

    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,...

  5. Heterooligomeric phosphoribosyl diphosphate synthase of Saccharomyces cerevisiae

    Hove-Jensen, Bjarne

    2004-01-01

    The yeast Saccharomyces cerevisiae contains five phosphoribosyl diphosphate (PRPP) synthase-homologous genes (PRS1-5), which specify PRPP synthase subunits 1-5. Expression of the five S. cerevisiae PRS genes individually in an Escherichia coli PRPP-less strain (Deltaprs) showed that a single PRS...

  6. Efeitos do cádmio sobre o crescimento das leveduras Saccharomyces cerevisiae PE-2 e Saccharomyces cerevisiae IZ-1904, e a capacidade da vinhaça em atenuar a toxicidade Effect of cadmium on the growth of two Saccharomyces cerevisiae strains, and the vinasse capacity to atenuate the toxicity

    Samuel Mariano-da-Silva

    2004-03-01

    , minimizando os efeitos deletérios do metal.The present study was carried out in order to evaluate the capability of different cadmium concentration (0; 0,05, 0,10 and 0,50mM to affect the growth of two S. cerevisiae strains (PE-2 and IZ-1904 in YED (yeast extract 1% and dextrose 2% medium, and to evaluate the three vinasse concentration capability (0,15 and 30% to attenuate the two cadmium concentration toxicity (0,1 and 0,5mM, using S. cerevisiae PE-2 strain in YED medium. In the first assay, the medium was inoculated in aseptic conditions with 1mL of 1% yeast suspension (PE-2 or IZ-1904 and incubated at 30ºC, 70 RPM for 18 hours. During anaerobic growth (0, 2, 4, 6, 8, 10, 12, 14, 16 and 18 hours, portions of cell suspension were taken out and biomass concentration was determined. At the end of fermentation, yeast viability, budding rate and bacterial contamination were determined. Both, initial and final trehalose, was measured. In the second assay, the medium was inoculated in aseptic conditions with 2mL of 1% PE-2 suspension and incubated at 30ºC, 120 rpm for 18 hours. During the anaerobic growth (0, 2, 4, 6, 8, 10, 12,14, 16 and 18 hours portions of cell suspension were taken out and biomass concentration was determined. At the end of fermentation, alcohol production, yeast viability, budding rate and bacterial contamination were determined. Both, initial and final trehalose, was measured. The increase of cadmium levels showed a reduction on yeast growth and cell viability. Vinasse showed low toxicity, but protected yeast cells very effectively against the toxic effects of cadmium.

  7. Constitutive modeling of polycarbonate over a wide range of strain rates and temperatures

    Wang, Haitao; Zhou, Huamin; Huang, Zhigao; Zhang, Yun; Zhao, Xiaoxuan

    2017-02-01

    The mechanical behavior of polycarbonate was experimentally investigated over a wide range of strain rates (10^{-4} to 5× 103 s^{-1}) and temperatures (293 to 353 K). Compression tests under these conditions were performed using a SHIMADZU universal testing machine and a split Hopkinson pressure bar. Falling weight impact testing was carried out on an Instron Dynatup 9200 drop tower system. The rate- and temperature-dependent deformation behavior of polycarbonate was discussed in detail. Dynamic mechanical analysis (DMA) tests were utilized to observe the glass (α ) transition and the secondary (β ) transition of polycarbonate. The DMA results indicate that the α and β transitions have a dramatic influence on the mechanical behavior of polycarbonate. The decompose/shift/reconstruct (DSR) method was utilized to decompose the storage modulus into the α and β components and extrapolate the entire modulus, the α-component modulus and the β-component modulus. Based on three previous models, namely, Mulliken-Boyce, G'Sell-Jonas and DSGZ, an adiabatic model is proposed to predict the mechanical behavior of polycarbonate. The model considers the contributions of both the α and β transitions to the mechanical behavior, and it has been implemented in ABAQUS/Explicit through a user material subroutine VUMAT. The model predictions are proven to essentially coincide with the experimental results during compression testing and falling weight impact testing.

  8. Fermentation of mixed glucose-xylose substrates by engineered strains of Saccharomyces cerevisiae: role of the coenzyme specificity of xylose reductase, and effect of glucose on xylose utilization

    Klimacek Mario

    2010-03-01

    Full Text Available Abstract Background In spite of the substantial metabolic engineering effort previously devoted to the development of Saccharomyces cerevisiae strains capable of fermenting both the hexose and pentose sugars present in lignocellulose hydrolysates, the productivity of reported strains for conversion of the naturally most abundant pentose, xylose, is still a major issue of process efficiency. Protein engineering for targeted alteration of the nicotinamide cofactor specificity of enzymes catalyzing the first steps in the metabolic pathway for xylose was a successful approach of reducing xylitol by-product formation and improving ethanol yield from xylose. The previously reported yeast strain BP10001, which expresses heterologous xylose reductase from Candida tenuis in mutated (NADH-preferring form, stands for a series of other yeast strains designed with similar rational. Using 20 g/L xylose as sole source of carbon, BP10001 displayed a low specific uptake rate qxylose (g xylose/g dry cell weight/h of 0.08. The study presented herein was performed with the aim of analysing (external factors that limit qxylose of BP10001 under xylose-only and mixed glucose-xylose substrate conditions. We also carried out a comprehensive investigation on the currently unclear role of coenzyme utilization, NADPH compared to NADH, for xylose reduction during co-fermentation of glucose and xylose. Results BP10001 and BP000, expressing C. tenuis xylose reductase in NADPH-preferring wild-type form, were used. Glucose and xylose (each at 10 g/L were converted sequentially, the corresponding qsubstrate values being similar for each strain (glucose: 3.0; xylose: 0.05. The distribution of fermentation products from glucose was identical for both strains whereas when using xylose, BP10001 showed enhanced ethanol yield (BP10001 0.30 g/g; BP000 0.23 g/g and decreased yields of xylitol (BP10001 0.26 g/g; BP000 0.36 g/g and glycerol (BP10001 0.023 g/g; BP000 0.072 g/g as compared

  9. Performance of the auxotrophic Saccharomyces cerevisiae BY4741 as host for the production of IL-1β in aerated fed-batch reactor: role of ACA supplementation, strain viability, and maintenance energy

    Zueco Jesus

    2009-12-01

    Full Text Available Abstract Background Saccharomyces cerevisiae BY4741 is an auxotrophic commonly used strain. In this work it has been used as host for the expression and secretion of human interleukin-1β (IL1β, using the cell wall protein Pir4 as fusion partner. To achieve high cell density and, consequently, high product yield, BY4741 [PIR4-IL1β] was cultured in an aerated fed-batch reactor, using a defined mineral medium supplemented with casamino acids as ACA (auxotrophy-complementing amino acid source. Also the S. cerevisiae mutant BY4741 Δyca1 [PIR4-IL1β], carrying the deletion of the YCA1 gene coding for a caspase-like protein involved in the apoptotic response, was cultured in aerated fed-batch reactor and compared to the parental strain, to test the effect of this mutation on strain robustness. Viability of the producer strains was examined during the runs and a mathematical model, which took into consideration the viable biomass present in the reactor and the glucose consumption for both growth and maintenance, was developed to describe and explain the time-course evolution of the process for both, the BY4741 parental and the BY4741 Δyca1 mutant strain. Results Our results show that the concentrations of ACA in the feeding solution, corresponding to those routinely used in the literature, are limiting for the growth of S. cerevisiae BY4741 [PIR4-IL1β] in fed-batch reactor. Even in the presence of a proper ACA supplementation, S. cerevisiae BY4741 [PIR4-IL1β] did not achieve a high cell density. The Δyca1 deletion did not have a beneficial effect on the overall performance of the strain, but it had a clear effect on its viability, which was not impaired during fed-batch operations, as shown by the kd value (0.0045 h-1, negligible if compared to that of the parental strain (0.028 h-1. However, independently of their robustness, both the parental and the Δyca1 mutant ceased to grow early during fed-batch runs, both strains using most of the

  10. Cell Size Influences the Reproductive Potential and Total Lifespan of the Saccharomyces cerevisiae Yeast as Revealed by the Analysis of Polyploid Strains

    Renata Zadrag-Tecza

    2018-01-01

    Full Text Available The total lifespan of the yeast Saccharomyces cerevisiae may be divided into two phases: the reproductive phase, during which the cell undergoes mitosis cycles to produce successive buds, and the postreproductive phase, which extends from the last division to cell death. These phases may be regulated by a common mechanism or by distinct ones. In this paper, we proposed a more comprehensive approach to reveal the mechanisms that regulate both reproductive potential and total lifespan in cell size context. Our study was based on yeast cells, whose size was determined by increased genome copy number, ranging from haploid to tetraploid. Such experiments enabled us to test the hypertrophy hypothesis, which postulates that excessive size achieved by the cell—the hypertrophy state—is the reason preventing the cell from further proliferation. This hypothesis defines the reproductive potential value as the difference between the maximal size that a cell can reach and the threshold value, which allows a cell to undergo its first cell cycle and the rate of the cell size to increase per generation. Here, we showed that cell size has an important impact on not only the reproductive potential but also the total lifespan of this cell. Moreover, the maximal cell size value, which limits its reproduction capacity, can be regulated by different factors and differs depending on the strain ploidy. The achievement of excessive size by the cell (hypertrophic state may lead to two distinct phenomena: the cessation of reproduction without “mother” cell death and the cessation of reproduction with cell death by bursting, which has not been shown before.

  11. Clostridium tyrobutyricum strains show wide variation in growth at different NaCl, pH, and temperature conditions.

    Ruusunen, Marjo; Surakka, Anu; Korkeala, Hannu; Lindström, Miia

    2012-10-01

    Outgrowth from Clostridium tyrobutyricum spores in milk can lead to butyric acid fermentation in cheeses, causing spoilage and economical loss to the dairy industry. The aim of this study was to investigate the growth of 10 C. tyrobutyricum strains at different NaCl, pH, and temperature conditions. Up to 7.5-fold differences among the maximum growth rates of different strains in the presence of 2.0% NaCl were observed. Five of 10 strains were able to grow in the presence of 3.0% NaCl, while a NaCl concentration of 3.5% was completely inhibitory to all strains. Seven of 10 strains were able to grow at pH 5.0, and up to 4- and 12.5-fold differences were observed among the maximum growth rates of different strains at pH 5.5 and 7.5, respectively. The maximum growth temperatures varied from 40.2 to 43.3°C. The temperature of 10°C inhibited the growth of all strains, while 8 of 10 strains grew at 12 and 15°C. Despite showing no growth, all strains were able to survive at 10°C. In conclusion, wide variation was observed among different C. tyrobutyricum strains in their ability to grow at different stressful conditions. Understanding the physiological diversity among the strains is important when designing food control measures and predictive models for the growth of spoilage organisms in cheese.

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

    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.

  13. Genome-wide polysomal analysis of a yeast strain with mutated ribosomal protein S9

    Arava Yoav

    2007-08-01

    Full Text Available Abstract Background The yeast ribosomal protein S9 (S9 is located at the entrance tunnel of the mRNA into the ribosome. It is known to play a role in accurate decoding and its bacterial homolog (S4 has recently been shown to be involved in opening RNA duplexes. Here we examined the effects of changing the C terminus of S9, which is rich in acidic amino acids and extends out of the ribosome surface. Results We performed a genome-wide analysis to reveal effects at the transcription and translation levels of all yeast genes. While negligible relative changes were observed in steady-state mRNA levels, a significant number of mRNAs appeared to have altered ribosomal density. Notably, 40% of the genes having reliable signals changed their ribosomal association by more than one ribosome. Yet, no general correlations with physical or functional features of the mRNA were observed. Ribosome Density Mapping (RDM along four of the mRNAs with increased association revealed an increase in ribosomal density towards the end of the coding region for at least two of them. Read-through analysis did not reveal any increase in read-through of a premature stop codon by the mutant strain. Conclusion The ribosomal protein rpS9 appears to be involved in the translation of many mRNAs, since altering its C terminus led to a significant change in ribosomal association of many mRNAs. We did not find strong correlations between these changes and several physical features of the mRNA, yet future studies with advanced tools may allow such correlations to be determined. Importantly, our results indicate an accumulation of ribosomes towards the end of the coding regions of some mRNAs. This suggests an involvement of S9 in ribosomal dissociation during translation termination.

  14. [Saccharomyces cerevisiae infections].

    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.

  15. Initial locomotor sensitivity to cocaine varies widely among inbred mouse strains.

    Wiltshire, T; Ervin, R B; Duan, H; Bogue, M A; Zamboni, W C; Cook, S; Chung, W; Zou, F; Tarantino, L M

    2015-03-01

    Initial sensitivity to psychostimulants can predict subsequent use and abuse in humans. Acute locomotor activation in response to psychostimulants is commonly used as an animal model of initial drug sensitivity and has been shown to have a substantial genetic component. Identifying the specific genetic differences that lead to phenotypic differences in initial drug sensitivity can advance our understanding of the processes that lead to addiction. Phenotyping inbred mouse strain panels are frequently used as a first step for studying the genetic architecture of complex traits. We assessed locomotor activation following a single, acute 20 mg/kg dose of cocaine (COC) in males from 45 inbred mouse strains and observed significant phenotypic variation across strains indicating a substantial genetic component. We also measured levels of COC, the active metabolite, norcocaine and the major inactive metabolite, benzoylecgonine, in plasma and brain in the same set of inbred strains. Pharmacokinetic (PK) and behavioral data were significantly correlated, but at a level that indicates that PK alone does not account for the behavioral differences observed across strains. Phenotypic data from this reference population of inbred strains can be utilized in studies aimed at examining the role of psychostimulant-induced locomotor activation on drug reward and reinforcement and to test theories about addiction processes. Moreover, these data serve as a starting point for identifying genes that alter sensitivity to the locomotor stimulatory effects of COC. © 2015 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.

  16. Mechanical response of AA7075 aluminum alloy over a wide range of temperatures and strain rates

    Jin, Z.; Cassada, W.A. [Reynolds Metals Co., Chester, VA (United States). Corp. Res. and Dev.; Cady, C.M.; Gray, G.T. III

    2000-07-01

    The influence of temperature and strain rate on the flow stress and work hardening rate of a 7075 aluminum alloy was studied under compressive loading over the temperature range from 23 C to 470 C, and strain rates from 0.001 s{sup -1} and 2100 s{sup -1}. While the temperature dependence of the flow stress was found to be most significant at temperatures below 300 C, the strain rate dependence of the flow stress was found to be pronounced at temperatures above 23 C. Concurrently, the work hardening rate decreases significantly with increasing temperature between 23 C and 300 C and increases slightly at higher temperatures. The minimum work hardening rate is observed to occur at temperatures between 200 C and 300 C and shift to higher temperatures with increasing strain rate. A negative strain rate dependence of work hardening rate was observed at 23 C, although a positive strain rate dependence of work hardening rate occurs at higher temperatures. Analysis of the experimental data revealed three deformation regimes. (orig.)

  17. Comparative genomic characterization of three Streptococcus parauberis strains in fish pathogen, as assessed by wide-genome analyses.

    Seong-Won Nho

    Full Text Available Streptococcus parauberis, which is the main causative agent of streptococcosis among olive flounder (Paralichthys olivaceus in northeast Asia, can be distinctly divided into two groups (type I and type II by an agglutination test. Here, the whole genome sequences of two Japanese strains (KRS-02083 and KRS-02109 were determined and compared with the previously determined genome of a Korean strain (KCTC 11537. The genomes of S. parauberis are intermediate in size and have lower GC contents than those of other streptococci. We annotated 2,236 and 2,048 genes in KRS-02083 and KRS-02109, respectively. Our results revealed that the three S. parauberis strains contain different genomic insertions and deletions. In particular, the genomes of Korean and Japanese strains encode different factors for sugar utilization; the former encodes the phosphotransferase system (PTS for sorbose, whereas the latter encodes proteins for lactose hydrolysis, respectively. And the KRS-02109 strain, specifically, was the type II strain found to be able to resist phage infection through the clustered regularly interspaced short palindromic repeats (CRISPR/Cas system and which might contribute valuably to serologically distribution. Thus, our genome-wide association study shows that polymorphisms can affect pathogen responses, providing insight into biological/biochemical pathways and phylogenetic diversity.

  18. Analysis of the genome-wide variations among multiple strains of the plant pathogenic bacterium Xylella fastidiosa

    Walker M Andrew

    2006-09-01

    Full Text Available Abstract Background The Gram-negative, xylem-limited phytopathogenic bacterium Xylella fastidiosa is responsible for causing economically important diseases in grapevine, citrus and many other plant species. Despite its economic impact, relatively little is known about the genomic variations among strains isolated from different hosts and their influence on the population genetics of this pathogen. With the availability of genome sequence information for four strains, it is now possible to perform genome-wide analyses to identify and categorize such DNA variations and to understand their influence on strain functional divergence. Results There are 1,579 genes and 194 non-coding homologous sequences present in the genomes of all four strains, representing a 76. 2% conservation of the sequenced genome. About 60% of the X. fastidiosa unique sequences exist as tandem gene clusters of 6 or more genes. Multiple alignments identified 12,754 SNPs and 14,449 INDELs in the 1528 common genes and 20,779 SNPs and 10,075 INDELs in the 194 non-coding sequences. The average SNP frequency was 1.08 × 10-2 per base pair of DNA and the average INDEL frequency was 2.06 × 10-2 per base pair of DNA. On an average, 60.33% of the SNPs were synonymous type while 39.67% were non-synonymous type. The mutation frequency, primarily in the form of external INDELs was the main type of sequence variation. The relative similarity between the strains was discussed according to the INDEL and SNP differences. The number of genes unique to each strain were 60 (9a5c, 54 (Dixon, 83 (Ann1 and 9 (Temecula-1. A sub-set of the strain specific genes showed significant differences in terms of their codon usage and GC composition from the native genes suggesting their xenologous origin. Tandem repeat analysis of the genomic sequences of the four strains identified associations of repeat sequences with hypothetical and phage related functions. Conclusion INDELs and strain specific genes

  19. Glucose repression in Saccharomyces cerevisiae

    Kayikci, Omur; Nielsen, Jens

    2015-01-01

    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 gluc......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...

  20. Adaption of Saccharomyces cerevisiae expressing a heterologous protein

    Krogh, Astrid Mørkeberg; Beck, Vibe; Højlund Christensen, Lars

    2008-01-01

    Production of the heterologous protein, bovine aprotinin, in Saccharomyces cerevisiae was shown to affect the metabolism of the host cell to various extent depending on the strain genotype. Strains with different genotypes, industrial and laboroatory, respectively, were investigated. The maximal...

  1. Heat shock response improves heterologous protein secretion in Saccharomyces cerevisiae

    Hou, Jin; Österlund, Tobias; Liu, Zihe

    2013-01-01

    The yeast Saccharomyces cerevisiae is a widely used platform for the production of heterologous proteins of medical or industrial interest. However, heterologous protein productivity is often low due to limitations of the host strain. Heat shock response (HSR) is an inducible, global, cellular...... stress response, which facilitates the cell recovery from many forms of stress, e.g., heat stress. In S. cerevisiae, HSR is regulated mainly by the transcription factor heat shock factor (Hsf1p) and many of its targets are genes coding for molecular chaperones that promote protein folding and prevent...... the accumulation of mis-folded or aggregated proteins. In this work, we over-expressed a mutant HSF1 gene HSF1-R206S which can constitutively activate HSR, so the heat shock response was induced at different levels, and we studied the impact of HSR on heterologous protein secretion. We found that moderate and high...

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

    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...

  3. Grain orientation and strain measurements in sub-micron wide passivated individual aluminum test structures

    Tamura, N.; Valek, B.C.; Spolenak, R.; MacDowell, A.A.; Celestre, R.S.; Padmore, H.A.; Brown, W.L.; Marieb, T.; Bravman, J.C.; Batterman, B.W.; Patel, J.R.

    2001-01-01

    An X-ray microdiffraction dedicated beamline, combining white and monochromatic beam capabilities, has been built at the Advanced Light Source. The purpose of this beamline is to address the myriad of problems in Materials Science and Physics that require submicron x-ray beams for structural characterization. Many such problems are found in the general area of thin films and nano-materials. For instance, the ability to characterize the orientation and strain state in individual grains of thin films allows us to measure structural changes at a very local level. These microstructural changes are influenced heavily by such parameters as deposition conditions and subsequent treatment. The accurate measurement of strain gradients at the micron and sub-micron level finds many applications ranging from the strain state under nano-indenters to gradients at crack tips. Undoubtedly many other applications will unfold in the future as we gain experience with the capabilities and limitations of this instrument. We have applied this technique to measure grain orientation and residual stress in single grains of pure Al interconnect lines and preliminary results on post-electromigration test experiments are presented. It is shown that measurements with this instrument can be used to resolve the complete stress tensor (6 components) in a submicron volume inside a single grain of Al under a passivation layer with an overall precision of about 20 MPa. The microstructure of passivated lines appears to be complex, with grains divided into identifiable subgrains and noticeable local variations of both tensile/compressive and shear stresses within single grains

  4. Comparisons of radiosensitivity and damage repair potential between mutants from the Saccharomyces cerevisiae strain of yeast and laboratory-bred wild yeasts with particular attention being given to giant cell formation after X-radiation

    Heinen, A.

    1988-01-01

    Yeast cells were exposed to X-rays at dose levels up to 10 kGy to induce damage to the DNA and investigate its effects on cellular growth patterns. For this purpose, comparisons were carried out between one diploid strain and six haploid strains of the Saccharomyces uvarum and Saccharomyces cerevisiae species, which permitted the individual recovery and damage repair pathways to be described in more detail. The laboratory-bred wild strains ATCC 9080, 211 and 706 were judged to have unimpaired repair mechanisms as compared to the auxotrophs, which fact was evident from the higher radiosensitivity of the latter. A further parameter in this evaluation of growth behaviours was giant cell formation. The results here provided evidence in confirmation of deviations between wild strains and mutants. Even though the ceiling values for the formation of giant cells were similarly high in all strains, impairments of cell division and initial development were observed for the mutants already at considerably lower dose levels. (orig./MG) [de

  5. A loss-of-function mutation in the PAS kinase Rim15p is related to defective quiescence entry and high fermentation rates of Saccharomyces cerevisiae sake yeast strains.

    Watanabe, Daisuke; Araki, Yuya; Zhou, Yan; Maeya, Naoki; Akao, Takeshi; Shimoi, Hitoshi

    2012-06-01

    Sake yeast cells have defective entry into the quiescent state, allowing them to sustain high fermentation rates. To reveal the underlying mechanism, we investigated the PAS kinase Rim15p, which orchestrates initiation of the quiescence program in Saccharomyces cerevisiae. We found that Rim15p is truncated at the carboxyl terminus in modern sake yeast strains as a result of a frameshift mutation. Introduction of this mutation or deletion of the full-length RIM15 gene in a laboratory strain led to a defective stress response, decreased synthesis of the storage carbohydrates trehalose and glycogen, and impaired G(1) arrest, which together closely resemble the characteristic phenotypes of sake yeast. Notably, expression of a functional RIM15 gene in a modern sake strain suppressed all of these phenotypes, demonstrating that dysfunction of Rim15p prevents sake yeast cells from entering quiescence. Moreover, loss of Rim15p or its downstream targets Igo1p and Igo2p remarkably improved the fermentation rate in a laboratory strain. This finding verified that Rim15p-mediated entry into quiescence plays pivotal roles in the inhibition of ethanol fermentation. Taken together, our results suggest that the loss-of-function mutation in the RIM15 gene may be the key genetic determinant of the increased ethanol production rates in modern sake yeast strains.

  6. Comparison of physically based constitutive models characterizing armor steel over wide temperature and strain rate ranges

    Xu, Zejian; Huang, Fenglei

    2012-01-01

    Both descriptive and predictive capabilities of five physically based constitutive models (PB, NNL, ZA, VA, and RK) are investigated and compared systematically, in characterizing plastic behavior of the 603 steel at temperatures ranging from 288 to 873 K, and strain rates ranging from 0.001 to 4500 s −1 . Determination of the constitutive parameters is introduced in detail for each model. Validities of the established models are checked by strain rate jump tests performed under different loading conditions. The results show that the RK and NNL models have better performance in the description of material behavior, especially the work-hardening effect, while the PB and VA models predict better. The inconsistency that is observed between the capabilities of description and prediction of the models indicates the existence of the minimum number of required fitting data, reflecting the degree of a model's requirement for basic data in parameter calibration. It is also found that the description capability of a model is dependent to a large extent on both its form and the number of its constitutive parameters, while the precision of prediction relies largely on the performance of description. In the selection of constitutive models, the experimental data and the constitutive models should be considered synthetically to obtain a better efficiency in material behavior characterization

  7. Development of a novel monoclonal antibody with reactivity to a wide range of Venezuelan equine encephalitis virus strains

    Phelps Amanda L

    2009-11-01

    Full Text Available Abstract Background There is currently a requirement for antiviral therapies capable of protecting against infection with Venezuelan equine encephalitis virus (VEEV, as a licensed vaccine is not available for general human use. Monoclonal antibodies are increasingly being developed as therapeutics and are potential treatments for VEEV as they have been shown to be protective in the mouse model of disease. However, to be truly effective, the antibody should recognise multiple strains of VEEV and broadly reactive monoclonal antibodies are rarely and only coincidentally isolated using classical hybridoma technology. Results In this work, methods were developed to reliably derive broadly reactive murine antibodies. A phage library was created that expressed single chain variable fragments (scFv isolated from mice immunised with multiple strains of VEEV. A broadly reactive scFv was identified and incorporated into a murine IgG2a framework. This novel antibody retained the broad reactivity exhibited by the scFv but did not possess virus neutralising activity. However, the antibody was still able to protect mice against VEEV disease induced by strain TrD when administered 24 h prior to challenge. Conclusion A monoclonal antibody possessing reactivity to a wide range of VEEV strains may be of benefit as a generic antiviral therapy. However, humanisation of the murine antibody will be required before it can be tested in humans. Crown Copyright © 2009

  8. Recent invasion of world-wide wheat growing areas by two aggressive strains of Puccinia striiformis

    Walter, Stephanie; Ali, Sajid; Justesen, Annemarie Fejer

    2012-01-01

    The ever more frequent and severe large-scale epidemics of wheat yellow/stripe rust disease (caused by Puccinia striiformis) pose a severe threat to the world’s wheat production (Hovmøller et al. 2010). The onset of a new series of world-wide wheat yellow rust epidemics in 2000 has been linked...

  9. Directed evolution of pyruvate decarboxylase-negative Saccharomyces cerevisiae, yielding a C2-independent, glucose-tolerant, and pyruvate-hyperproducing yeast

    A.J. van Maris; J.M. Geertman; A. Vermeulen; M.K. Groothuizen; A.A. Winkler; M.D. Piper; J.P. van Dijken; J.T. Pronk

    2004-01-01

    textabstractThe absence of alcoholic fermentation makes pyruvate decarboxylase-negative (Pdc(-)) strains of Saccharomyces cerevisiae an interesting platform for further metabolic engineering of central metabolism. However, Pdc(-) S. cerevisiae strains have two growth defects:

  10. Yersinia pestis strains of ancient phylogenetic branch 0.ANT are widely spread in the high-mountain plague foci of Kyrgyzstan.

    Eroshenko, Galina A; Nosov, Nikita Yu; Krasnov, Yaroslav M; Oglodin, Yevgeny G; Kukleva, Lyubov M; Guseva, Natalia P; Kuznetsov, Alexander A; Abdikarimov, Sabyrzhan T; Dzhaparova, Aigul K; Kutyrev, Vladimir V

    2017-01-01

    Fifty six Yersinia pestis strains, isolated over the period of more than 50 years in three high-mountain foci of Kyrgyzstan (Tien Shan, Alai, and Talas), have been characterized by means of PCR and single nucleotide polymorphism (SNP) typing methods. Seven of these strains were also characterized by means of whole genome sequencing and genome-wide SNP phylogenetic analysis. It was found that forty two strains belong to 0.ANT2, 0.ANT3 and 0.ANT5 phylogenetic branches. From these, strains of 0.ANT2 and 0.ANT3 branches were earlier detected in China only, whereas 0.ANT5 phylogenetic branch was identified for Y. pestis phylogeny for the first time. According to the results of genome-wide SNP analysis, 0.ANT5 strains are ones of the most closely related to Y. pestis strain responsible for the Justinianic Plague. We have also found out that four of the studied strains belong to the phylogenetic branch 2.MED1, and ten strains from Talas high-mountain focus belong to the phylogenetic branch 0.PE4 (sub-branch 0.PE4t). Established diversity of Y. pestis strains and extensive dissemination of the strains pertaining to the 0.ANT branch confirm the antiquity of the mentioned above plague foci and suggest that strains of the 0.ANT branch, which serve as precursors for all highly virulent Y. pestis strains, had their origin in the Tien Shan mountains.

  11. Comparative study of bio-ethanol production from mahula (Madhuca latifolia L.) flowers by Saccharomyces cerevisiae and Zymomonas mobilis

    Behera, Shuvashish; Mohanty, Rama Chandra [Department of Botany, Utkal University, Vanivihar, Bhubaneswar 751004, Orissa (India); Ray, Ramesh Chandra [Microbiology Laboratory, Central Tuber Crops Research Institute (Regional Centre), Bhubaneswar 751019, Orissa (India)

    2010-07-15

    Mahula (Madhuca latifolia L.) flower is a suitable alternative cheaper carbohydrate source for production of bio-ethanol. Recent production of bio-ethanol by microbial fermentation as an alternative energy source has renewed research interest because of the increase in the fuel price. Saccharomyces cerevisiae (yeast) and Zymomonas mobilis (bacteria) are two most widely used microorganisms for ethanol production. In this study, experiments were carried out to compare the potential of the yeast S. cerevisiae (CTCRI strain) with the bacterium Z. mobilis (MTCC 92) for ethanol fermentation from mahula flowers. The ethanol production after 96 h fermentation was 149 and 122.9 g kg{sup -1} flowers using free cells of S. cerevisiae and Z. mobilis, respectively. The S. cerevisiae strain showed 21.2% more final ethanol production in comparison to Z. mobilis. Ethanol yield (Yx/s), volumetric product productivity (Qp), sugar to ethanol conversion rate (%) and microbial biomass concentration (X) obtained by S. cerevisiae were found to be 5.2%, 21.1%, 5.27% and 134% higher than Z. mobilis, respectively after 96 h of fermentation. (author)

  12. Comparative study of bio-ethanol production from mahula (Madhuca latifolia L.) flowers by Saccharomyces cerevisiae and Zymomonas mobilis

    Behera, Shuvashish; Mohanty, Rama Chandra; Ray, Ramesh Chandra

    2010-01-01

    Mahula (Madhuca latifolia L.) flower is a suitable alternative cheaper carbohydrate source for production of bio-ethanol. Recent production of bio-ethanol by microbial fermentation as an alternative energy source has renewed research interest because of the increase in the fuel price. Saccharomyces cerevisiae (yeast) and Zymomonas mobilis (bacteria) are two most widely used microorganisms for ethanol production. In this study, experiments were carried out to compare the potential of the yeast S. cerevisiae (CTCRI strain) with the bacterium Z. mobilis (MTCC 92) for ethanol fermentation from mahula flowers. The ethanol production after 96 h fermentation was 149 and 122.9 g kg -1 flowers using free cells of S. cerevisiae and Z. mobilis, respectively. The S. cerevisiae strain showed 21.2% more final ethanol production in comparison to Z. mobilis. Ethanol yield (Yx/s), volumetric product productivity (Qp), sugar to ethanol conversion rate (%) and microbial biomass concentration (X) obtained by S. cerevisiae were found to be 5.2%, 21.1%, 5.27% and 134% higher than Z. mobilis, respectively after 96 h of fermentation. (author)

  13. Effect of dilution rate and nutrients addition on the fermentative capability and synthesis of aromatic compounds of two indigenous strains of Saccharomyces cerevisiae in continuous cultures fed with Agave tequilana juice.

    Morán-Marroquín, G A; Córdova, J; Valle-Rodríguez, J O; Estarrón-Espinosa, M; Díaz-Montaño, D M

    2011-11-15

    Knowledge of physiological behavior of indigenous tequila yeast used in fermentation process is still limited. Yeasts have significant impact on the productivity fermentation process as well as the sensorial characteristics of the alcoholic beverage. For these reasons a better knowledge of the physiological and metabolic features of these yeasts is required. The effects of dilution rate, nitrogen and phosphorus source addition and micro-aeration on growth, fermentation and synthesis of volatile compounds of two native Saccharomyces cerevisiae strains, cultured in continuous fed with Agave tequilana juice were studied. For S1 and S2 strains, maximal concentrations of biomass, ethanol, consumed sugars, alcohols and esters were obtained at 0.04 h⁻¹. Those concentrations quickly decreased as D increased. For S. cerevisiae S1 cultures (at D=0.08 h⁻¹) supplemented with ammonium phosphate (AP) from 1 to 4 g/L, concentrations of residual sugars decreased from 29.42 to 17.60 g/L and ethanol increased from 29.63 to 40.08 g/L, respectively. The S1 culture supplemented with AP was then micro-aerated from 0 to 0.02 vvm, improving all the kinetics parameters: biomass, ethanol and glycerol concentrations increased from 5.66, 40.08 and 3.11 g/L to 8.04, 45.91 and 4.88 g/L; residual sugars decreased from 17.67 g/L to 4.48 g/L; and rates of productions of biomass and ethanol, and consumption of sugars increased from 0.45, 3.21 and 7.33 g/L·h to 0.64, 3.67 and 8.38 g/L·h, respectively. Concentrations of volatile compounds were also influenced by the micro-aeration rate. Ester and alcohol concentrations were higher, in none aerated and in aerated cultures respectively. Copyright © 2011. Published by Elsevier B.V.

  14. A vaccine grade of yeast Saccharomyces cerevisiae expressing mammalian myostatin

    Zhang Tingting

    2012-12-01

    Full Text Available Abstract Background Yeast Saccharomyces cerevisiae is a widely-used system for protein expression. We previously showed that heat-killed whole recombinant yeast vaccine expressing mammalian myostatin can modulate myostatin function in mice, resulting in increase of body weight and muscle composition in these animals. Foreign DNA introduced into yeast cells can be lost soon unless cells are continuously cultured in selection media, which usually contain antibiotics. For cost and safety concerns, it is essential to optimize conditions to produce quality food and pharmaceutical products. Results We developed a simple but effective method to engineer a yeast strain stably expressing mammalian myostatin. This method utilized high-copy-number integration of myostatin gene into the ribosomal DNA of Saccharomyces cerevisiae. In the final step, antibiotic selection marker was removed using the Cre-LoxP system to minimize any possible side-effects for animals. The resulting yeast strain can be maintained in rich culture media and stably express mammalian myostatin for two years. Oral administration of the recombinant yeast was able to induce immune response to myostatin and modulated the body weight of mice. Conclusions Establishment of such yeast strain is a step further toward transformation of yeast cells into edible vaccine to improve meat production in farm animals and treat human muscle-wasting diseases in the future.

  15. A genome-wide analysis of nonribosomal peptide synthetase gene clusters and their peptides in a Planktothrix rubescens strain

    Nederbragt Alexander J

    2009-08-01

    Full Text Available Abstract Background Cyanobacteria often produce several different oligopeptides, with unknown biological functions, by nonribosomal peptide synthetases (NRPS. Although some cyanobacterial NRPS gene cluster types are well described, the entire NRPS genomic content within a single cyanobacterial strain has never been investigated. Here we have combined a genome-wide analysis using massive parallel pyrosequencing ("454" and mass spectrometry screening of oligopeptides produced in the strain Planktothrix rubescens NIVA CYA 98 in order to identify all putative gene clusters for oligopeptides. Results Thirteen types of oligopeptides were uncovered by mass spectrometry (MS analyses. Microcystin, cyanopeptolin and aeruginosin synthetases, highly similar to already characterized NRPS, were present in the genome. Two novel NRPS gene clusters were associated with production of anabaenopeptins and microginins, respectively. Sequence-depth of the genome and real-time PCR data revealed three copies of the microginin gene cluster. Since NRPS gene cluster candidates for microviridin and oscillatorin synthesis could not be found, putative (gene encoded precursor peptide sequences to microviridin and oscillatorin were found in the genes mdnA and oscA, respectively. The genes flanking the microviridin and oscillatorin precursor genes encode putative modifying enzymes of the precursor oligopeptides. We therefore propose ribosomal pathways involving modifications and cyclisation for microviridin and oscillatorin. The microviridin, anabaenopeptin and cyanopeptolin gene clusters are situated in close proximity to each other, constituting an oligopeptide island. Conclusion Altogether seven nonribosomal peptide synthetase (NRPS gene clusters and two gene clusters putatively encoding ribosomal oligopeptide biosynthetic pathways were revealed. Our results demonstrate that whole genome shotgun sequencing combined with MS-directed determination of oligopeptides successfully

  16. Sphingomonas wittichii Strain RW1 Genome-Wide Gene Expression Shifts in Response to Dioxins and Clay.

    Benli Chai

    Full Text Available Sphingomonas wittichii strain RW1 (RW1 is one of the few strains that can grow on dibenzo-p-dioxin (DD. We conducted a transcriptomic study of RW1 using RNA-Seq to outline transcriptional responses to DD, dibenzofuran (DF, and the smectite clay mineral saponite with succinate as carbon source. The ability to grow on DD is rare compared to growth on the chemically similar DF even though the same initial dioxygenase may be involved in oxidation of both substrates. Therefore, we hypothesized the reason for this lies beyond catabolic pathways and may concern genes involved in processes for cell-substrate interactions such as substrate recognition, transport, and detoxification. Compared to succinate (SUC as control carbon source, DF caused over 240 protein-coding genes to be differentially expressed, whereas more than 300 were differentially expressed with DD. Stress response genes were up-regulated in response to both DD and DF. This effect was stronger with DD than DF, suggesting a higher toxicity of DD compared to DF. Both DD and DF caused changes in expression of genes involved in active cross-membrane transport such as TonB-dependent receptor proteins, but the patterns of change differed between the two substrates. Multiple transcription factor genes also displayed expression patterns distinct to DD and DF growth. DD and DF induced the catechol ortho- and the salicylate/gentisate pathways, respectively. Both DD and DF induced the shared down-stream aliphatic intermediate compound pathway. Clay caused category-wide down-regulation of genes for cell motility and chemotaxis, particularly those involved in the synthesis, assembly and functioning of flagella. This is an environmentally important finding because clay is a major component of soil microbes' microenvironment influencing local chemistry and may serve as a geosorbent for toxic pollutants. Similar to clay, DD and DF also affected expression of genes involved in motility and chemotaxis.

  17. Improvement of lactic acid production in Saccharomyces cerevisiae by a deletion of ssb1.

    Lee, Jinsuk J; Crook, Nathan; Sun, Jie; Alper, Hal S

    2016-01-01

    Polylactic acid (PLA) is an important renewable polymer, but current processes for producing its precursor, lactic acid, suffer from process inefficiencies related to the use of bacterial hosts. Therefore, improving the capacity of Saccharomyces cerevisiae to produce lactic acid is a promising approach to improve industrial production of lactic acid. As one such improvement required, the lactic acid tolerance of yeast must be significantly increased. To enable improved tolerance, we employed an RNAi-mediated genome-wide expression knockdown approach as a means to rapidly identify potential genetic targets. In this approach, several gene knockdown targets were identified which confer increased acid tolerance to S. cerevisiae BY4741, of which knockdown of the ribosome-associated chaperone SSB1 conferred the highest increase (52%). This target was then transferred into a lactic acid-overproducing strain of S. cerevisiae CEN.PK in the form of a knockout and the resulting strain demonstrated up to 33% increased cell growth, 58% increased glucose consumption, and 60% increased L-lactic acid production. As SSB1 contains a close functional homolog SSB2 in yeast, this result was counterintuitive and may point to as-yet-undefined functional differences between SSB1 and SSB2 related to lactic acid production. The final strain produced over 50 g/L of lactic acid in under 60 h of fermentation.

  18. Hybridization of Palm Wine Yeasts ( Saccharomyces Cerevisiae ...

    Haploid auxotrophic strains of Saccharomyces cerevisiae were selected from palm wine and propagated by protoplast fusion with Brewers yeast. Fusion resulted in an increase in both ethanol production and tolerance against exogenous ethanol. Mean fusion frequencies obtained for a mating types ranged between 8 x ...

  19. Optimization of ethanol, citric acid, and α-amylase production from date wastes by strains of Saccharomyces cerevisiae, Aspergillus niger, and Candida guilliermondii.

    Acourene, S; Ammouche, A

    2012-05-01

    The present study deals with submerged ethanol, citric acid, and α-amylase fermentation by Saccharomyces cerevisiae SDB, Aspergillus niger ANSS-B5, and Candida guilliermondii CGL-A10, using date wastes as the basal fermentation medium. The physical and chemical parameters influencing the production of these metabolites were optimized. As for the ethanol production, the optimum yield obtained was 136.00 ± 0.66 g/l under optimum conditions of an incubation period of 72 h, inoculum content of 4% (w/v), sugars concentration of 180.0 g/l, and ammonium phosphate concentration of 1.0 g/l. Concerning citric acid production, the cumulative effect of temperature (30°C), sugars concentration of 150.0 g/l, methanol concentration of 3.0%, initial pH of 3.5, ammonium nitrate concentration of 2.5 g/l, and potassium phosphate concentration of 2.5 g/l during the fermentation process of date wastes syrup did increase the citric acid production to 98.42 ± 1.41 g/l. For the production of α-amylase, the obtained result shows that the presence of starch strongly induces the production of α-amylase with a maximum at 5.0 g/l. Among the various nitrogen sources tested, urea at 5.0 g/l gave the maximum biomass and α-amylase estimated at 5.76 ± 0.56 g/l and 2,304.19 ± 31.08 μmol/l/min, respectively after 72 h incubation at 30°C, with an initial pH of 6.0 and potassium phosphate concentration of 6.0 g/l.

  20. Invertase SUC2 Is the Key Hydrolase for Inulin Degradation in Saccharomyces cerevisiae

    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.

  1. Characterization of global yeast quantitative proteome data generated from the wild-type and glucose repression Saccharomyces cerevisiae strains: The comparison of two quantitative methods

    Usaite, Renata; Wohlschlegel, James; Venable, John D.

    2008-01-01

    The quantitative proteomic analysis of complex protein mixtures is emerging as a technically challenging but viable systems-level approach for studying cellular function. This study presents a large-scale comparative analysis of protein abundances from yeast protein lysates derived from both wild......-type yeast and yeast strains lacking key components of the Snf1 kinase complex. Four different strains were grown under well-controlled chemostat conditions. Multidimensional protein identification technology followed by quantitation using either spectral counting or stable isotope labeling approaches...... labeling strategy. The stable isotope labeling based quantitative approach was found to be highly reproducible among biological replicates when complex protein mixtures containing small expression changes were analyzed. Where poor correlation between stable isotope labeling and spectral counting was found...

  2. Continent-Wide Estimates of Antarctic Strain Rates from Landsat 8-Derived Velocity Grids and Their Application to Ice Shelf Studies

    Alley, K. E.; Scambos, T.; Anderson, R. S.; Rajaram, H.; Pope, A.; Haran, T.

    2017-12-01

    Strain rates are fundamental measures of ice flow used in a wide variety of glaciological applications including investigations of bed properties, calculations of basal mass balance on ice shelves, application to Glen's flow law, and many other studies. However, despite their extensive application, strain rates are calculated using widely varying methods and length scales, and the calculation details are often not specified. In this study, we compare the results of nominal and logarithmic strain-rate calculations based on a satellite-derived velocity field of the Antarctic ice sheet generated from Landsat 8 satellite data. Our comparison highlights the differences between the two commonly used approaches in the glaciological literature. We evaluate the errors introduced by each code and their impacts on the results. We also demonstrate the importance of choosing and specifying a length scale over which strain-rate calculations are made, which can have large local impacts on other derived quantities such as basal mass balance on ice shelves. We present strain-rate data products calculated using an approximate viscous length-scale with satellite observations of ice velocity for the Antarctic continent. Finally, we explore the applications of comprehensive strain-rate maps to future ice shelf studies, including investigations of ice fracture, calving patterns, and stability analyses.

  3. Genome-wide analytical approaches for reverse metabolic engineering of industrially relevant phenotypes in yeast

    Oud, Bart; Maris, Antonius J A; Daran, Jean-Marc; Pronk, Jack T

    2012-01-01

    Successful reverse engineering of mutants that have been obtained by nontargeted strain improvement has long presented a major challenge in yeast biotechnology. This paper reviews the use of genome-wide approaches for analysis of Saccharomyces cerevisiae strains originating from evolutionary engineering or random mutagenesis. On the basis of an evaluation of the strengths and weaknesses of different methods, we conclude that for the initial identification of relevant genetic changes, whole genome sequencing is superior to other analytical techniques, such as transcriptome, metabolome, proteome, or array-based genome analysis. Key advantages of this technique over gene expression analysis include the independency of genome sequences on experimental context and the possibility to directly and precisely reproduce the identified changes in naive strains. The predictive value of genome-wide analysis of strains with industrially relevant characteristics can be further improved by classical genetics or simultaneous analysis of strains derived from parallel, independent strain improvement lineages. PMID:22152095

  4. Effects of post-treatment incubation on recombinogenesis in incision-proficient and incision-deficient strains of saccharomyces cerevisiae, 2

    Saeki, Tetsuya; Machida, Isamu

    1991-01-01

    After the photoaddition of mono- and bifunctional furocoumarins to G1 phase cells, most gene conversion and crossing-over occurred without post-irradiation incubation of these cells in incision-proficient strains. In contrast, incision-deficient cells showed marked induction of both recombinational events only after treated cells had been incubated for several hours before selection. These results indicate that when furocoumarins are photoadded to G1 cells, initiation of recombinational events occurs during the same G1 phase in the incision-proficient cells; whereas, it occurs only after post-irradiation DNA replication in incision-deficient cells. The action of the PSO2 gene product specific for the repair of DNA crosslinks in recombination induction is discussed and compared to the actions of the excision repair genes RAD1 and RAD2. (author)

  5. Evidence against a photoprotective component of photoreactivation in Saccharomyces cerevisiae

    MacQuillan, A.M.; Green, G.; Perry, W.G.

    1981-01-01

    Photoreactivation-deficient (phr - ) mutants of Saccharomyces cerevisiae were shown to lack in vitro DNA-photolyase activity. A phr - mutant was then compared with a phr + strain for near-UV induced photoprotection from far-UV irradiation. Neither strain exhibited a photoprotective effect. (author)

  6. Improving monoterpene geraniol production through geranyl diphosphate synthesis regulation in Saccharomyces cerevisiae.

    Zhao, Jianzhi; Bao, Xiaoming; Li, Chen; Shen, Yu; Hou, Jin

    2016-05-01

    Monoterpenes have wide applications in the food, cosmetics, and medicine industries and have recently received increased attention as advanced biofuels. However, compared with sesquiterpenes, monoterpene production is still lagging in Saccharomyces cerevisiae. In this study, geraniol, a valuable acyclic monoterpene alcohol, was synthesized in S. cerevisiae. We evaluated three geraniol synthases in S. cerevisiae, and the geraniol synthase Valeriana officinalis (tVoGES), which lacked a plastid-targeting peptide, yielded the highest geraniol production. To improve geraniol production, synthesis of the precursor geranyl diphosphate (GPP) was regulated by comparing three specific GPP synthase genes derived from different plants and the endogenous farnesyl diphosphate synthase gene variants ERG20 (G) (ERG20 (K197G) ) and ERG20 (WW) (ERG20 (F96W-N127W) ), and controlling endogenous ERG20 expression, coupled with increasing the expression of the mevalonate pathway by co-overexpressing IDI1, tHMG1, and UPC2-1. The results showed that overexpressing ERG20 (WW) and strengthening the mevalonate pathway significantly improved geraniol production, while expressing heterologous GPP synthase genes or down-regulating endogenous ERG20 expression did not show positive effect. In addition, we constructed an Erg20p(F96W-N127W)-tVoGES fusion protein, and geraniol production reached 66.2 mg/L after optimizing the amino acid linker and the order of the proteins. The best strain yielded 293 mg/L geraniol in a fed-batch cultivation, a sevenfold improvement over the highest titer previously reported in an engineered S. cerevisiae strain. Finally, we showed that the toxicity of geraniol limited its production. The platform developed here can be readily used to synthesize other monoterpenes.

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

    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.

  8. Genomic Characterization of Urethritis-Associated Neisseria meningitidis Shows that a Wide Range of N. meningitidis Strains Can Cause Urethritis.

    Ma, Kevin C; Unemo, Magnus; Jeverica, Samo; Kirkcaldy, Robert D; Takahashi, Hideyuki; Ohnishi, Makoto; Grad, Yonatan H

    2017-12-01

    Neisseria meningitidis , typically a resident of the oro- or nasopharynx and the causative agent of meningococcal meningitis and meningococcemia, is capable of invading and colonizing the urogenital tract. This can result in urethritis, akin to the syndrome caused by its sister species, N. gonorrhoeae , the etiologic agent of gonorrhea. Recently, meningococcal strains associated with outbreaks of urethritis were reported to share genetic characteristics with the gonococcus, raising the question of the extent to which these strains contain features that promote adaptation to the genitourinary niche, making them gonococcus-like and distinguishing them from other N. meningitidis strains. Here, we analyzed the genomes of 39 diverse N. meningitidis isolates associated with urethritis, collected independently over a decade and across three continents. In particular, we characterized the diversity of the nitrite reductase gene ( aniA ), the factor H-binding protein gene ( fHbp ), and the capsule biosynthetic locus, all of which are loci previously suggested to be associated with urogenital colonization. We observed notable diversity, including frameshift variants, in aniA and fHbp and the presence of intact, disrupted, and absent capsule biosynthetic genes, indicating that urogenital colonization and urethritis caused by N. meningitidis are possible across a range of meningococcal genotypes. Previously identified allelic patterns in urethritis-associated N. meningitidis strains may reflect genetic diversity in the underlying meningococcal population rather than novel adaptation to the urogenital tract. Copyright © 2017 American Society for Microbiology.

  9. Draft Genome Sequence of Bacillus coagulans GBI-30, 6086, a Widely Used Spore-Forming Probiotic Strain

    Orrù, Luigi; Salvetti, Elisa; Cattivelli, Luigi; Lamontanara, Antonella; Michelotti, Vania; Capozzi, Vittorio; Spano, Giuseppe; Keller, David; Cash, Howard; Martina, Alessia; Torriani, Sandra; Felis, Giovanna E.

    2014-01-01

    Bacillus coagulans GBI-30, 6086 is a safe strain, already available on the market, and characterized by certified beneficial effects. The draft genome sequence presented here constitutes the first pillar toward the identification of the molecular mechanisms responsible for its positive features and safety.

  10. Draft Genome Sequence of Bacillus coagulans GBI-30, 6086, a Widely Used Spore-Forming Probiotic Strain

    Orrù, Luigi; Salvetti, Elisa; Cattivelli, Luigi; Lamontanara, Antonella; Michelotti, Vania; Capozzi, Vittorio; Spano, Giuseppe; Keller, David; Cash, Howard; Martina, Alessia; Felis, Giovanna E.

    2014-01-01

    Bacillus coagulans GBI-30, 6086 is a safe strain, already available on the market, and characterized by certified beneficial effects. The draft genome sequence presented here constitutes the first pillar toward the identification of the molecular mechanisms responsible for its positive features and safety. PMID:25377698

  11. Genome-wide study of the defective sucrose fermenter strain of Vibrio cholerae from the Latin American cholera epidemic.

    Daniel Rios Garza

    Full Text Available The 7th cholera pandemic reached Latin America in 1991, spreading from Peru to virtually all Latin American countries. During the late epidemic period, a strain that failed to ferment sucrose dominated cholera outbreaks in the Northern Brazilian Amazon region. In order to understand the genomic characteristics and the determinants of this altered sucrose fermenting phenotype, the genome of the strain IEC224 was sequenced. This paper reports a broad genomic study of this strain, showing its correlation with the major epidemic lineage. The potentially mobile genomic regions are shown to possess GC content deviation, and harbor the main V. cholera virulence genes. A novel bioinformatic approach was applied in order to identify the putative functions of hypothetical proteins, and was compared with the automatic annotation by RAST. The genome of a large bacteriophage was found to be integrated to the IEC224's alanine aminopeptidase gene. The presence of this phage is shown to be a common characteristic of the El Tor strains from the Latin American epidemic, as well as its putative ancestor from Angola. The defective sucrose fermenting phenotype is shown to be due to a single nucleotide insertion in the V. cholerae sucrose-specific transportation gene. This frame-shift mutation truncated a membrane protein, altering its structural pore-like conformation. Further, the identification of a common bacteriophage reinforces both the monophyletic and African-Origin hypotheses for the main causative agent of the 1991 Latin America cholera epidemics.

  12. Genome-wide study of the defective sucrose fermenter strain of Vibrio cholerae from the Latin American cholera epidemic.

    Garza, D.R.; Thompson, C.C.; Loureiro, E.C.; Dutilh, B.E.; Inada, D.T.; Junior, E.C.; Cardoso, J.F.; Nunes, M.R.; Lima, C.P. de; Silvestre, R.V.; Nunes, K.N.; Santos, E.C.; Edwards, R.A.; Vicente, A.C.; Sa Morais, L.L. de

    2012-01-01

    The 7th cholera pandemic reached Latin America in 1991, spreading from Peru to virtually all Latin American countries. During the late epidemic period, a strain that failed to ferment sucrose dominated cholera outbreaks in the Northern Brazilian Amazon region. In order to understand the genomic

  13. Genome-wide comparison and taxonomic relatedness of multiple Xylella fastidiosa strains reveal the occurrence of three subspecies and a new Xylella species.

    Marcelletti, Simone; Scortichini, Marco

    2016-10-01

    A total of 21 Xylella fastidiosa strains were assessed by comparing their genomes to infer their taxonomic relationships. The whole-genome-based average nucleotide identity and tetranucleotide frequency correlation coefficient analyses were performed. In addition, a consensus tree based on comparisons of 956 core gene families, and a genome-wide phylogenetic tree and a Neighbor-net network were constructed with 820,088 nucleotides (i.e., approximately 30-33 % of the entire X. fastidiosa genome). All approaches revealed the occurrence of three well-demarcated genetic clusters that represent X. fastidiosa subspecies fastidiosa, multiplex and pauca, with the latter appeared to diverge. We suggest that the proposed but never formally described subspecies 'sandyi' and 'morus' are instead members of the subspecies fastidiosa. These analyses support the view that the Xylella strain isolated from Pyrus pyrifolia in Taiwan is likely to be a new species. A widely used multilocus sequence typing analysis yielded conflicting results.

  14. Insights Gained from the Dehalococcoides ethenogenes Strain 195’s Transcriptome Responding to a Wide Range of Respiration Rates and Substrate Types

    2012-04-01

    fermented yeast , pure hydrogen, or endogenous biomass decay). When similarly respiring (~120 ?eeq PCE/(L-hr)) batch and PSS cultures were contrasted, the...REPORT Insights gained from the “Dehalococcoides ethenogenes” strain 195?s transcriptome responding to a wide range of respiration rates and substrate...types. 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Bacteria of the group “Dehalococcoides” display the ability to respire recalcitrant chlorinated

  15. Stress Tolerance in Doughs of Saccharomyces cerevisiae Trehalase Mutants Derived from Commercial Baker’s Yeast

    Shima, Jun; Hino, Akihiro; Yamada-Iyo, Chie; Suzuki, Yasuo; Nakajima, Ryouichi; Watanabe, Hajime; Mori, Katsumi; Takano, Hiroyuki

    1999-01-01

    Accumulation of trehalose is widely believed to be a critical determinant in improving the stress tolerance of the yeast Saccharomyces cerevisiae, which is commonly used in commercial bread dough. To retain the accumulation of trehalose in yeast cells, we constructed, for the first time, diploid homozygous neutral trehalase mutants (Δnth1), acid trehalase mutants (Δath1), and double mutants (Δnth1 ath1) by using commercial baker’s yeast strains as the parent strains and the gene disruption method. During fermentation in a liquid fermentation medium, degradation of intracellular trehalose was inhibited with all of the trehalase mutants. The gassing power of frozen doughs made with these mutants was greater than the gassing power of doughs made with the parent strains. The Δnth1 and Δath1 strains also exhibited higher levels of tolerance of dry conditions than the parent strains exhibited; however, the Δnth1 ath1 strain exhibited lower tolerance of dry conditions than the parent strain exhibited. The improved freeze tolerance exhibited by all of the trehalase mutants may make these strains useful in frozen dough. PMID:10388673

  16. Genome-Wide Immune Modulation of TLR3-Mediated Inflammation in Intestinal Epithelial Cells Differs between Single and Multi-Strain Probiotic Combination.

    Chad W MacPherson

    Full Text Available Genome-wide transcriptional analysis in intestinal epithelial cells (IEC can aid in elucidating the impact of single versus multi-strain probiotic combinations on immunological and cellular mechanisms of action. In this study we used human expression microarray chips in an in vitro intestinal epithelial cell model to investigate the impact of three probiotic bacteria, Lactobacillus helveticus R0052 (Lh-R0052, Bifidobacterium longum subsp. infantis R0033 (Bl-R0033 and Bifidobacterium bifidum R0071 (Bb-R0071 individually and in combination, and of a surface-layer protein (SLP purified from Lh-R0052, on HT-29 cells' transcriptional profile to poly(I:C-induced inflammation. Hierarchical heat map clustering, Set Distiller and String analyses revealed that the effects of Lh-R0052 and Bb-R0071 diverged from those of Bl-R0033 and Lh-R0052-SLP. It was evident from the global analyses with respect to the immune, cellular and homeostasis related pathways that the co-challenge with probiotic combination (PC vastly differed in its effect from the single strains and Lh-R0052-SLP treatments. The multi-strain PC resulted in a greater reduction of modulated genes, found through functional connections between immune and cellular pathways. Cytokine and chemokine analyses based on specific outcomes from the TNF-α and NF-κB signaling pathways revealed single, multi-strain and Lh-R0052-SLP specific attenuation of the majority of proteins measured (TNF-α, IL-8, CXCL1, CXCL2 and CXCL10, indicating potentially different mechanisms. These findings indicate a synergistic effect of the bacterial combinations relative to the single strain and Lh-R0052-SLP treatments in resolving toll-like receptor 3 (TLR3-induced inflammation in IEC and maintaining cellular homeostasis, reinforcing the rationale for using multi-strain formulations as a probiotic.

  17. Engineering of carbon catabolite repression in recombinant xylose fermenting Saccharomyces cerevisiae

    Roca, Christophe Francois Aime; Haack, Martin Brian; Olsson, Lisbeth

    2004-01-01

    analysed for changes in xylose consumption rate and ethanol production rate during anaerobic batch and chemostat cultivations on a mixture of 20 g l(-1) glucose and 50 g l(-1) xylose, and their characteristics were compared to the parental strain S. cerevisiae TMB3001 (XYL1, XYL2, XKS1). Improvement...... that xylose is a repressive sugar for S. cerevisiae....

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

    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...

  19. Characterization of Fluorescent Proteins for Three- and Four-Color Live-Cell Imaging in S. cerevisiae.

    Higuchi-Sanabria, Ryo; Garcia, Enrique J; Tomoiaga, Delia; Munteanu, Emilia L; Feinstein, Paul; Pon, Liza A

    2016-01-01

    Saccharomyces cerevisiae are widely used for imaging fluorescently tagged protein fusions. Fluorescent proteins can easily be inserted into yeast genes at their chromosomal locus, by homologous recombination, for expression of tagged proteins at endogenous levels. This is especially useful for incorporation of multiple fluorescent protein fusions into a single strain, which can be challenging in organisms where genetic manipulation is more complex. However, the availability of optimal fluorescent protein combinations for 3-color imaging is limited. Here, we have characterized a combination of fluorescent proteins, mTFP1/mCitrine/mCherry for multicolor live cell imaging in S. cerevisiae. This combination can be used with conventional blue dyes, such as DAPI, for potential four-color live cell imaging.

  20. EasyCloneMulti: A Set of Vectors for Simultaneous and Multiple Genomic Integrations in Saccharomyces cerevisiae

    Maury, Jerome; Germann, Susanne Manuela; Jacobsen, Simo Abdessamad

    2016-01-01

    Saccharomyces cerevisiae is widely used in the biotechnology industry for production of ethanol, recombinant proteins, food ingredients and other chemicals. In order to generate highly producing and stable strains, genome integration of genes encoding metabolic pathway enzymes is the preferred...... of integrative vectors, EasyCloneMulti, that enables multiple and simultaneous integration of genes in S. cerevisiae. By creating vector backbones that combine consensus sequences that aim at targeting subsets of Ty sequences and a quickly degrading selective marker, integrations at multiple genomic loci...... and a range of expression levels were obtained, as assessed with the green fluorescent protein (GFP) reporter system. The EasyCloneMulti vector set was applied to balance the expression of the rate-controlling step in the β-alanine pathway for biosynthesis of 3-hydroxypropionic acid (3HP). The best 3HP...

  1. 2μ plasmid in Saccharomyces species and in Saccharomyces cerevisiae.

    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.

  2. Functional co-operation between the nuclei of Saccharomyces cerevisiae and mitochondria from other yeast species

    Spirek, M.; Horvath, A.; Piskur, Jure

    2000-01-01

    We elaborated a simple method that allows the transfer of mitochondria from collection yeasts to Saccharomyces cerevisiae. Protoplasts prepared from different yeasts were fused to the protoplasts of the ade2-1, ura3-52, kar1-1, rho (0) strain of S. cerevisiae and were selected for respiring cybrids....... italicus, S, oviformis, S. capensis and S. chevalieri) exhibited complete compatibility with S. cerevisiae nuclei. The closely related S. douglasii mitochondrial genome could also partially restore respiration-deficiency in rho (0) S. cerevisiae, whereas mitochondrial genomes from phylogenetically less...

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

    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.

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

    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

  5. Multiplexed CRISPR/Cas9 Genome Editing and Gene Regulation Using Csy4 in Saccharomyces cerevisiae

    Ferreira, Raphael; Skrekas, Christos; Nielsen, Jens

    2018-01-01

    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...

  6. Construction of killer industrial yeast Saccharomyces cerevisiae HAU-1 and its fermentation performance

    Bijender K. Bajaj

    2010-06-01

    Full Text Available Saccharomyces cerevisiae HAU-1, a time tested industrial yeast possesses most of the desirable fermentation characteristics like fast growth and fermentation rate, osmotolerance, high ethanol tolerance, ability to ferment molasses, and to ferment at elevated temperatures etc. However, this yeast was found to be sensitive against the killer strains of Saccharomyces cerevisiae. In the present study, killer trait was introduced into Saccharomyces cerevisiae HAU-1 by protoplast fusion with Saccharomyces cerevisiae MTCC 475, a killer strain. The resultant fusants were characterized for desirable fermentation characteristics. All the technologically important characteristics of distillery yeast Saccharomyces cerevisiae HAU-1 were retained in the fusants, and in addition the killer trait was also introduced into them. Further, the killer activity was found to be stably maintained during hostile conditions of ethanol fermentations in dextrose or molasses, and even during biomass recycling.

  7. Genetic evidence for a high diversity and wide distribution of endemic strains of the pathogenic chytrid fungus Batrachochytrium dendrobatidis in wild Asian amphibians.

    Bataille, Arnaud; Fong, Jonathan J; Cha, Moonsuk; Wogan, Guinevere O U; Baek, Hae Jun; Lee, Hang; Min, Mi-Sook; Waldman, Bruce

    2013-08-01

    Population declines and extinctions of amphibians have been attributed to the chytrid fungus Batrachochytrium dendrobatidis (Bd), especially one globally emerging recombinant lineage ('Bd-GPL'). We used PCR assays that target the ribosomal internal transcribed spacer region (ITS) of Bd to determine the prevalence and genetic diversity of Bd in South Korea, where Bd is widely distributed but is not known to cause morbidity or mortality in wild populations. We isolated Korean Bd strains from native amphibians with low infection loads and compared them to known worldwide Bd strains using 19 polymorphic SNP and microsatellite loci. Bd prevalence ranged between 12.5 and 48.0%, in 11 of 17 native Korean species, and 24.7% in the introduced bullfrog Lithobates catesbeianus. Based on ITS sequence variation, 47 of the 50 identified Korean haplotypes formed a group closely associated with a native Brazilian Bd lineage, separated from the Bd-GPL lineage. However, multilocus genotyping of three Korean Bd isolates revealed strong divergence from both Bd-GPL and the native Brazilian Bd lineages. Thus, the ITS region resolves genotypes that diverge from Bd-GPL but otherwise generates ambiguous phylogenies. Our results point to the presence of highly diversified endemic strains of Bd across Asian amphibian species. The rarity of Bd-GPL-associated haplotypes suggests that either this lineage was introduced into Korea only recently or Bd-GPL has been outcompeted by native Bd strains. Our results highlight the need to consider possible complex interactions among native Bd lineages, Bd-GPL and their associated amphibian hosts when assessing the spread and impact of Bd-GPL on worldwide amphibian populations. © 2013 John Wiley & Sons Ltd.

  8. 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.

    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.

  9. Glucose repression in Saccharomyces cerevisiae.

    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.

  10. Kinetics of formation of induced mutants of Saccharomyces cerevisiae

    Chepurnoj, A.I.; Levkovich, N.V.; Mikhova-Tsenova, N.; Mel'nikova, L.A.

    1990-01-01

    UV and γ-radiation mutagenic effect an various strains of Saccharomyces cerevisiae was studied by analyzing formation kinetics of induced mutants at the period of postirradiation incubation. Mechanisms of induced reverse formation was suggested. The presented analysis is considered to be differential taking account of more subtle aspects of induced mutagenesis. 8 refs.; 10 figs.; 3 tabs

  11. Reconstitution of an efficient thymidine salvage pathway in Saccharomyces cerevisiae

    Vernis, L.; Piskur, Jure; Diffley, J.F.X.

    2003-01-01

    The budding yeast Saccharomyces cerevisiae is unable to incorporate exogenous nucleosides into DNA. We have made a number of improvements to existing strategies to reconstitute an efficient thymidine salvage pathway in yeast. We have constructed strains that express both a nucleoside kinase as well...

  12. Habitat Predicts Levels of Genetic Admixture in Saccharomyces cerevisiae

    Viranga Tilakaratna

    2017-09-01

    Full Text Available 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.

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

    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.

  14. Brazilian propolis protects Saccharomyces cerevisiae cells against oxidative stress

    Rafael A. de Sá

    2013-09-01

    Full Text Available Propolis is a natural product widely used for humans. Due to its complex composition, a number of applications (antimicrobial, antiinflammatory, anesthetic, cytostatic and antioxidant have been attributed to this substance. Using Saccharomyces cerevisiae as a eukaryotic model we investigated the mechanisms underlying the antioxidant effect of propolis from Guarapari against oxidative stress. Submitting a wild type (BY4741 and antioxidant deficient strains (ctt1∆, sod1∆, gsh1∆, gtt1∆ and gtt2∆ either to 15 mM menadione or to 2 mM hydrogen peroxide during 60 min, we observed that all strains, except the mutant sod1∆, acquired tolerance when previously treated with 25 µg/mL of alcoholic propolis extract. Such a treatment reduced the levels of ROS generation and of lipid peroxidation, after oxidative stress. The increase in Cu/Zn-Sod activity by propolis suggests that the protection might be acting synergistically with Cu/Zn-Sod.

  15. Mechanisms of iron sensing and regulation in the yeast Saccharomyces cerevisiae.

    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.

  16. Quality and Composition of Red Wine Fermented with Schizosaccharomyces pombe as Sole Fermentative Yeast, and in Mixed and Sequential Fermentations with Saccharomyces cerevisiae

    Felipe Palomero

    2014-01-01

    Full Text Available This work examines the physiology of Schizosaccharomyces pombe (represented by strain 938 in the production of red wine, as the sole fermentative yeast, and in mixed and sequential fermentations with Saccharomyces cerevisiae 796. For further comparison, fermentations in which Saccharomyces cerevisiae was the sole fermentative yeast were also performed; in these fermentations a commercial lactic acid bacterium was used to perform malolactic fermentation once alcoholic fermentation was complete (unlike S. cerevisiae, the Sc. pombe performs maloalcoholic fermentation and therefore removes malic acid without such help. Relative density, acetic, malic and pyruvic acid concentrations, primary amino nitrogen and urea concentrations, and pH of the musts were measured over the entire fermentation period. In all fermentations in which Sc. pombe 938 was involved, nearly all the malic acid was consumed from an initial concentration of 5.5 g/L, and moderate acetic acid concentrations below 0.4 g/L were formed. The urea content of these wines was notably lower, showing a tenfold reduction when compared with those that were made with S. cerevisiae 796 alone. The sensorial properties of the different final wines varied widely. The wines fermented with Sc. pombe 938 had maximum aroma intensity and quality, and they were preferred by the tasters.

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

    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.

  18. Induction of homologous recombination in Saccharomyces cerevisiae.

    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.

  19. Saccharomyces cerevisiae show low levels of traversal across human endothelial barrier in vitro [version 2; referees: 2 approved

    Roberto Pérez-Torrado

    2017-09-01

    Full Text Available 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.

  20. Accumulation of gold using Baker's yeast, Saccharomyces cerevisiae

    Roy, Kamalika; Lahiri, Susanta; Sinha, P.

    2006-01-01

    Authors have reported preconcentration of 152 Eu, a long-lived fission product, by yeast cells, Saccharomyces cerevisiae. Gold being a precious metal is used in electroplating, hydrogenation catalyst, etc. Heterogeneous composition of samples and low concentration offers renewed interest in its selective extraction of gold using various extractants. Gold can be recovered from different solutions using various chemical reagents like amines, organophosphorus compounds, and extractants containing sulphur as donor atom, etc. In the present work, two different strains of baker's yeast, Saccharomyces cerevisiae have been used to study the preconcentration of gold at various experimental conditions

  1. Fumaric acid production in Saccharomyces cerevisiae by in silico aided metabolic engineering.

    Guoqiang Xu

    Full Text Available Fumaric acid (FA is a promising biomass-derived building-block chemical. Bio-based FA production from renewable feedstock is a promising and sustainable alternative to petroleum-based chemical synthesis. Here we report on FA production by direct fermentation using metabolically engineered Saccharomyces cerevisiae with the aid of in silico analysis of a genome-scale metabolic model. First, FUM1 was selected as the target gene on the basis of extensive literature mining. Flux balance analysis (FBA revealed that FUM1 deletion can lead to FA production and slightly lower growth of S. cerevisiae. The engineered S. cerevisiae strain obtained by deleting FUM1 can produce FA up to a concentration of 610±31 mg L(-1 without any apparent change in growth in fed-batch culture. FT-IR and (1H and (13C NMR spectra confirmed that FA was synthesized by the engineered S. cerevisiae strain. FBA identified pyruvate carboxylase as one of the factors limiting higher FA production. When the RoPYC gene was introduced, S. cerevisiae produced 1134±48 mg L(-1 FA. Furthermore, the final engineered S. cerevisiae strain was able to produce 1675±52 mg L(-1 FA in batch culture when the SFC1 gene encoding a succinate-fumarate transporter was introduced. These results demonstrate that the model shows great predictive capability for metabolic engineering. Moreover, FA production in S. cerevisiae can be efficiently developed with the aid of in silico metabolic engineering.

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

    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

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

    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.

  4. Adaptive answer to low ionizing radiation doses in Saccharomyces cerevisiae; Respuesta adaptativa a bajas dosis de radiacion ionizante en Saccharomyces cerevisiae

    Durand, Jorge L. [Comision Nacional de Energia Atomica, San Carlos de Bariloche (Argentina). Inst. Balseiro; Frati, Diego Libkind; Broock, Maria Van [Universidad Nacional del Comahue, Bariloche (Argentina). Centro Regional Universitario Bariloche; Gillette, Victor [Comision Nacional de Energia Atomica, San Carlos de Bariloche (Argentina). Centro Atomico

    2001-07-01

    The aim of this work is to verify the existence of the adaptive response phenomenon induced by low doses of ionizing radiation in living cells. It is known that low doses of ionizing radiation, called conditioning doses, may induce resistance in exposed organisms to higher doses, called challenging doses, which are applied after a period of time. The involved mechanisms in this phenomenon, called Adaptive Response, are diverse and complex. Among them, the most important are the activation of DNA-repair enzymes and nuclear recombination process. As the 'target' sample, it was utilized a 'wild type' strain of Saccharomyces cerevisiae in aqueous suspension. Adaptive Response was verified in a wide range of challenging doses. Conditioning doses, inductors of radio-resistance, were (0.44{+-}0.03) Gy and the waiting time between them and challenging doses was 2 hours at room temperature.(author)

  5. An internal deletion in MTH1 enables growth on glucose of pyruvate-decarboxylase negative, non-fermentative Saccharomyces cerevisiae

    Oud, B.; Flores, C.L.; Gancedo, C.; Zhang, X.; Trueheart, J.; Daran, J.M.; Pronk, J.T.; Van Maris, A.J.A.

    2012-01-01

    Background Pyruvate-decarboxylase negative (Pdc-) strains of Saccharomyces cerevisiae combine the robustness and high glycolytic capacity of this yeast with the absence of alcoholic fermentation. This makes Pdc-S. cerevisiae an interesting platform for efficient conversion of glucose towards

  6. The influence of sucrose and maltose on Saccharomyces cerevisiae yeast multiplication

    O. I. Ponomareva

    2016-01-01

    Full Text Available The data on the influence of fermentable carbohydrates concentration on yeast multiplication are widely represented in the literature. This study presents the results of experiments showing an influence of sucrose and maltose concentration on Saccharomyces cerevisiae yeast multiplication. The objects of this research are bakery, beer, wine and alcohol yeast that are widely used in fermentation industry. Beet molasses and malt wort were chosen as nutrient medium for yeast breeding. Their basic sugars are mainly represented by sucrose and maltose. The concentration of sugars was 9, 12, 16 and 20%. The intensity of yeast multiplication was evaluated based on yeast cells concentration during their cultivation and the specific growth rate. Sugar concentrations causing an intensive accumulation of examined yeast strains were determined. This paper presents the experimental data that were received describing the influence of sucrose and maltose concentration on the duration of a lag phase period for different yeast strains. Specific growth rates of researched strains were determined for nutrient mediums with different glucose and maltose concentrations. It was found that the Crabtree effect, that is caused by high carbohydrates concentration in culture medium, is most pronounced when yeast cells grow on a sucrose medium. Brewer’s and baker's yeast are more adapted to high concentrations of carbohydrates. The obtained experimental data could be utilized to develop flow charts of growing a pure culture of Saccharomyces cerevisiae yeast to use at fermentation plants, including low power ones.

  7. Indigenous Saccharomyces cerevisiae yeasts as a source of biodiversity for the selection of starters for specific fermentations

    Capece Angela

    2014-01-01

    Full Text Available The long-time studies on wine yeasts have determined a wide diffusion of inoculated fermentations by commercial starters, mainly of Saccharomyces. Although the use of starter cultures has improved the reproducibility of wine quality, the main drawback to this practice is the lack of the typical traits of wines produced by spontaneous fermentation. These findings have stimulated wine-researchers and wine-makers towards the selection of autochthonous strains as starter cultures. The objective of this study was to investigate the biodiversity of 167 S. cerevisiae yeasts, isolated from spontaneous fermentation of grapes. The genetic variability of isolates was evaluated by PCR amplification of inter-δ region with primer pair δ2/δ12. The same isolates were investigated for characteristics of oenological interest, such as resistance to sulphur dioxide, ethanol and copper and hydrogen sulphide production. On the basis of technological and molecular results, 20 strains were chosen and tested into inoculated fermentations at laboratory scale. The experimental wines were analyzed for the content of some by-products correlated to wine aroma, such as higher alcohols, acetaldehyde, ethyl acetate and acetic acid. One selected strain was used as starter culture to perform fermentation at cellar level. The selection program followed during this research project represents an optimal combination between two different trends in modern winemaking: the use of S. cerevisiae as starter cultures and the starter culture selection for specific fermentations.

  8. Directed Evolution towards Increased Isoprenoid Production in Saccharomyces cerevisiae

    Carlsen, Simon; Nielsen, Michael Lynge; Kielland-Brandt, Morten

    production can easily be scaled to meet current demands and it is also an environmental benign production method compared to organic synthesis. Thus it would be attractive to engineer a microorganism to produce high amounts of IPP and other immediate prenyl precursors such as geranyl pyrophosphate, farnesyl...... for discovering new genetic perturbations, which would results in and increased production of isoprenoids by S. cerevisiae has been very limited. This project is focus on creating diversity within a lycopene producing S. cerevisiae strain by construction of gDNA-, cDNA-, and transposon-libraries. The diversified...... coloration which is the result of higher amount of lycopene is being produced and hence high amount of isoprenoid precursor being available. This will elucidate novel genetic targets for increasing isoprenoid production in S. cerevisiae...

  9. The effect of acetaminophen on ubiquitin homeostasis in Saccharomyces cerevisiae.

    Angelina Huseinovic

    Full Text Available Acetaminophen (APAP, although considered a safe drug, is one of the major causes of acute liver failure by overdose, and therapeutic chronic use can cause serious health problems. Although the reactive APAP metabolite N-acetyl-p-benzoquinoneimine (NAPQI is clearly linked to liver toxicity, toxicity of APAP is also found without drug metabolism of APAP to NAPQI. To get more insight into mechanisms of APAP toxicity, a genome-wide screen in Saccharomyces cerevisiae for APAP-resistant deletion strains was performed. In this screen we identified genes related to the DNA damage response. Next, we investigated the link between genotype and APAP-induced toxicity or resistance by performing a more detailed screen with a library containing mutants of 1522 genes related to nuclear processes, like DNA repair and chromatin remodelling. We identified 233 strains that had an altered growth rate relative to wild type, of which 107 showed increased resistance to APAP and 126 showed increased sensitivity. Gene Ontology analysis identified ubiquitin homeostasis, regulation of transcription of RNA polymerase II genes, and the mitochondria-to-nucleus signalling pathway to be associated with APAP resistance, while histone exchange and modification, and vesicular transport were connected to APAP sensitivity. Indeed, we observed a link between ubiquitin levels and APAP resistance, whereby ubiquitin deficiency conferred resistance to APAP toxicity while ubiquitin overexpression resulted in sensitivity. The toxicity profile of various chemicals, APAP, and its positional isomer AMAP on a series of deletion strains with ubiquitin deficiency showed a unique resistance pattern for APAP. Furthermore, exposure to APAP increased the level of free ubiquitin and influenced the ubiquitination of proteins. Together, these results uncover a role for ubiquitin homeostasis in APAP-induced toxicity.

  10. Response of Saccharomyces cerevisiae to cadmium stress

    Moreira, Luciana Mara Costa; Ribeiro, Frederico Haddad; Neves, Maria Jose; Porto, Barbara Abranches Araujo; Amaral, Angela M.; Menezes, Maria Angela B.C.; Rosa, Carlos Augusto

    2009-01-01

    The intensification of industrial activity has been greatly contributing with the increase of heavy metals in the environment. Among these heavy metals, cadmium becomes a serious pervasive environmental pollutant. The cadmium is a heavy metal with no biological function, very toxic and carcinogenic at low concentrations. The toxicity of cadmium and several other metals can be mainly attributed to the multiplicity of coordination complexes and clusters that they can form. Some aspects of the cellular response to cadmium were extensively investigated in the yeast Saccharomyces cerevisiae. The primary site of interaction between many toxic metals and microbial cells is the plasma membrane. Plasma-membrane permeabilisation has been reported in a variety of microorganisms following cadmium exposure, and is considered one mechanism of cadmium toxicity in the yeast. In this work, using the yeast strain S. cerevisiae W303-WT, we have investigated the relationships between Cd uptake and release of cellular metal ions (K + and Na + ) using neutron activation technique. The neutron activation was an easy, rapid and suitable technique for doing these metal determinations on yeast cells; was observed the change in morphology of the strains during the process of Cd accumulation, these alterations were observed by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) during incorporation of cadmium. (author)

  11. Response of Saccharomyces cerevisiae to cadmium stress

    Moreira, Luciana Mara Costa; Ribeiro, Frederico Haddad; Neves, Maria Jose [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Lab. de Radiobiologia], e-mail: luamatu@uol.com.br; Porto, Barbara Abranches Araujo; Amaral, Angela M.; Menezes, Maria Angela B.C. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Lab. de Ativacao Neutronica], e-mail: menezes@cdtn.br; Rosa, Carlos Augusto [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Microbiologia], e-mail: carlrosa@icb.ufmg

    2009-07-01

    The intensification of industrial activity has been greatly contributing with the increase of heavy metals in the environment. Among these heavy metals, cadmium becomes a serious pervasive environmental pollutant. The cadmium is a heavy metal with no biological function, very toxic and carcinogenic at low concentrations. The toxicity of cadmium and several other metals can be mainly attributed to the multiplicity of coordination complexes and clusters that they can form. Some aspects of the cellular response to cadmium were extensively investigated in the yeast Saccharomyces cerevisiae. The primary site of interaction between many toxic metals and microbial cells is the plasma membrane. Plasma-membrane permeabilisation has been reported in a variety of microorganisms following cadmium exposure, and is considered one mechanism of cadmium toxicity in the yeast. In this work, using the yeast strain S. cerevisiae W303-WT, we have investigated the relationships between Cd uptake and release of cellular metal ions (K{sup +} and Na{sup +}) using neutron activation technique. The neutron activation was an easy, rapid and suitable technique for doing these metal determinations on yeast cells; was observed the change in morphology of the strains during the process of Cd accumulation, these alterations were observed by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) during incorporation of cadmium. (author)

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

    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.

  13. Modification of mutation frequency in Saccharomyces Cerevisiae

    Vashishat, R.K.; Kakar, S.N.

    1976-01-01

    In a reverse mutation system, using haploid, histidine-requirinq strain of Saccharomyces cerevisiae, the frequency of uv-induced prototrophs increased if the post-irradiation minimal medium was supplemented with limited amounts of histidine. Addition of natural amino acids or RNA bases in the post-irradiation minimal medium, with or without histidine, also increased the uv-induced mutation frequency. Thus, post-irradiation conditions favouring protein and RNA synthesis, are effective in increasing uv-induced mutations in yeast. As compared to uv light, nitrous acid was more effective in inducing reversions in this strain and the frequency increased if the treated cells were plated on minimal medium supplemented with limited amounts of histidine. However, the addition of amino acids or RNA bases decreased the number of revertants. An additional inclusion of histidine reversed the suppressive effect of these metabolites. The mutation induction processes are thus different or differently modifiable in uv and nitrous acid. (author)

  14. Simultaneous overexpression of enzymes of the lower part of glycolysis can enhance the fermentative capacity of Saccharomyces cerevisiae

    Smits, H. P.; Hauf, J.; Muller, S.

    2000-01-01

    Recombinant S. cerevisiae strains, with elevated levels of the enzymes of lower glycolysis (glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate mutase, phosphoglycerate kinase, enolase, pyruvate kinase, pyruvate decarboxylase and alcohol dehydrogenase) were physiologically characterized...

  15. Current strain accumulation in the hinterland of the northwest Himalaya constrained by landscape analyses, basin-wide denudation rates, and low temperature thermochronology

    Morell, Kristin D.; Sandiford, Mike; Kohn, Barry; Codilean, Alexandru; Fülöp, Réka-H.; Ahmad, Talat

    2017-11-01

    Rupture associated with the 25 April 2015 Mw 7.8 Gorkha (Nepal) earthquake highlighted our incomplete understanding of the structural architecture and seismic cycle processes that lead to Himalayan mountain building in Central Nepal. In this paper we investigate the style and kinematics of active mountain building in the Himalayan hinterland of Northwest India, approximately 400 km to the west of the hypocenter of the Nepal earthquake, via a combination of landscape metrics and long- (Ma) and short-term (ka) erosion rate estimates (from low temperature thermochronometry and basin-wide denudation rate estimates from 10Be concentrations). We focus our analysis on the area straddling the PT2, the physiographic transition between the Lesser and High Himalaya that has yielded important insights into the nature of hinterland deformation across much of the Himalaya. Our results from Northwest India reveal a distinctive PT2 that separates a Lesser Himalaya region with moderate relief (∼1000 m) and relatively slow erosion (400 km distance between them, similar spatiotemporal patterns of erosion and deformation observed in Northwest India and Central Nepal suggest both regions experience similar styles of active strain accumulation and both are susceptible to large seismic events.

  16. Dominance of Saccharomyces cerevisiae in alcoholic fermentation processes

    Albergaria, Helena; Arneborg, Nils

    2016-01-01

    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...

  17. Repair of UV-damaged incoming plasmid DNA in Saccharomyces cerevisiae

    Keszenman-Pereyra, David

    1990-01-01

    A whole-cell transformation assay was used for the repair of UV-damaged plasma DNA in highly-transformable haploid strains of Saccharomyces cerevisiae having different repair capabilities. The experiments described demonstrate that three epistasis groups (Friedberg 1988) are involved in the repair of UV-incoming DNA and that the repair processes act less efficiently on incoming DNA than they do on chromosomal DNA. The implications of these findings for UV repair in Saccharomyces cerevisiae are discussed. (author)

  18. Saccharomyces cerevisiae in the Production of Whisk(ey

    Graeme M. Walker

    2016-12-01

    Full Text Available Whisk(ey is a major global distilled spirit beverage. Whiskies are produced from cereal starches that are saccharified, fermented and distilled prior to spirit maturation. The strain of Saccharomyces cerevisiae employed in whisky fermentations is crucially important not only in terms of ethanol yields, but also for production of minor yeast metabolites which collectively contribute to development of spirit flavour and aroma characteristics. Distillers must therefore pay very careful attention to the strain of yeast exploited to ensure consistency of fermentation performance and spirit congener profiles. In the Scotch whisky industry, initiatives to address sustainability issues facing the industry (for example, reduced energy and water usage have resulted in a growing awareness regarding criteria for selecting new distilling yeasts with improved efficiency. For example, there is now a desire for Scotch whisky distilling yeasts to perform under more challenging conditions such as high gravity wort fermentations. This article highlights the important roles of S. cerevisiae strains in whisky production (with particular emphasis on Scotch and describes key fermentation performance attributes sought in distiller’s yeast, such as high alcohol yields, stress tolerance and desirable congener profiles. We hope that the information herein will be useful for whisky producers and yeast suppliers in selecting new distilling strains of S. cerevisiae, and for the scientific community to stimulate further research in this area.

  19. Switching the mode of sucrose utilization by Saccharomyces cerevisiae

    Miletti Luiz C

    2008-02-01

    Full Text Available Abstract 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

  20. Switching the mode of sucrose utilization by Saccharomyces cerevisiae.

    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

  1. Rapid and Efficient CRISPR/Cas9-Based Mating-Type Switching of Saccharomyces cerevisiae

    Ze-Xiong Xie

    2018-01-01

    Full Text Available Rapid and highly efficient mating-type switching of Saccharomyces cerevisiae enables a wide variety of genetic manipulations, such as the construction of strains, for instance, isogenic haploid pairs of both mating-types, diploids and polyploids. We used the CRISPR/Cas9 system to generate a double-strand break at the MAT locus and, in a single cotransformation, both haploid and diploid cells were switched to the specified mating-type at ∼80% efficiency. The mating-type of strains carrying either rod or ring chromosome III were switched, including those lacking HMLα and HMRa cryptic mating loci. Furthermore, we transplanted the synthetic yeast chromosome V to build a haploid polysynthetic chromosome strain by using this method together with an endoreduplication intercross strategy. The CRISPR/Cas9 mating-type switching method will be useful in building the complete synthetic yeast (Sc2.0 genome. Importantly, it is a generally useful method to build polyploids of a defined genotype and generally expedites strain construction, for example, in the construction of fully a/a/α/α isogenic tetraploids.

  2. Saccharomyces cerevisiae Mixed Culture of Blackberry (Rubus ulmifolius L.) Juice: Synergism in the Aroma Compounds Production

    Ragazzo-Sánchez, Juan Arturo; Ortiz-Basurto, Rosa Isela; Luna-Solano, Guadalupe; Calderón-Santoyo, Montserrat

    2014-01-01

    Blackberry (Rubus sp.) juice was fermented using four different strains of Saccharomyces cerevisiae (Vitilevure-CM4457, Enoferm-T306, ICV-K1, and Greroche Rhona-L3574) recognized because of their use in the wine industry. A medium alcoholic graduation spirit (component analysis (PCA), and factorial discriminant analysis (DFA) permit to demonstrate the synergism between the strains. PMID:25506606

  3. Quality parameters and RAPD-PCR differentiation of commercial baker's yeast and hybrid strains.

    El-Fiky, Zaki A; Hassan, Gamal M; Emam, Ahmed M

    2012-06-01

    Baker's yeast, Saccharomyces cerevisiae, is a key component in bread baking. Total of 12 commercial baker's yeast and 2 hybrid strains were compared using traditional quality parameters. Total of 5 strains with high leavening power and the 2 hybrid strains were selected and evaluated for their alpha-amylase, maltase, glucoamylase enzymes, and compared using random amplified polymorphic DNA (RAPD). The results revealed that all selected yeast strains have a low level of alpha-amylase and a high level of maltase and glucoamylase enzymes. Meanwhile, the Egyptian yeast strain (EY) had the highest content of alpha-amylase and maltase enzymes followed by the hybrid YH strain. The EY and YH strains have the highest content of glucoamylase enzyme almost with the same level. The RAPD banding patterns showed a wide variation among commercial yeast and hybrid strains. The closely related Egyptian yeast strains (EY and AL) demonstrated close similarity of their genotypes. The 2 hybrid strains were clustered to Turkish and European strains in 1 group. The authors conclude that the identification of strains and hybrids using RAPD technique was useful in determining their genetic relationship. These results can be useful not only for the basic research, but also for the quality control in baking factories. © 2012 Institute of Food Technologists®

  4. Stress tolerance and growth physiology of yeast strains from the Brazilian fuel ethanol industry.

    Della-Bianca, B E; Gombert, A K

    2013-12-01

    Improved biofuels production requires a better understanding of industrial microorganisms. Some wild Saccharomyces cerevisiae strains, isolated from the fuel ethanol industry in Brazil, present exceptional fermentation performance, persistence and prevalence in the harsh industrial environment. Nevertheless, their physiology has not yet been systematically investigated. Here we present a first systematic evaluation of the widely used industrial strains PE-2, CAT-1, BG-1 and JP1, in terms of their tolerance towards process-related stressors. We also analyzed their growth physiology under heat stress. These strains were evaluated in parallel to laboratory and baker's strains. Whereas the industrial strains performed in general better than the laboratory strains under ethanol or acetic acid stresses and on industrial media, high sugar stress was tolerated equally by all strains. Heat and low pH stresses clearly distinguished fuel ethanol strains from the others, indicating that these conditions might be the ones that mostly exert selective pressure on cells in the industrial environment. During shake-flask cultivations using a synthetic medium at 37 °C, industrial strains presented higher ethanol yields on glucose than the laboratory strains, indicating that they could have been selected for this trait-a response to energy-demanding fermentation conditions. These results might be useful to guide future improvements of large-scale fuel ethanol production via engineering of stress tolerance traits in other strains, and eventually also for promoting the use of these fuel ethanol strains in different industrial bioprocesses.

  5. Fungal genomics beyond Saccharomyces cerevisiae?

    Hofmann, Gerald; Mcintyre, Mhairi; Nielsen, Jens

    2003-01-01

    Fungi are used extensively in both fundamental research and industrial applications. Saccharomyces cerevisiae has been the model organism for fungal research for many years, particularly in functional genomics. However, considering the diversity within the fungal kingdom, it is obvious...

  6. 13C Metabolic Flux Analysis for systematic metabolic engineering of S. cerevisiae for overproduction of fatty acids.

    Amit Ghosh

    2016-10-01

    Full Text Available Efficient redirection of microbial metabolism into the abundant production of desired bioproducts remains non-trivial. Here we used flux-based modeling approaches to improve yields of fatty acids in S. cerevisiae. We combined 13C labeling data with comprehensive genome-scale models to shed light onto microbial metabolism and improve metabolic engineering efforts. We concentrated on studying the balance of acetyl-CoA, a precursor metabolite for the biosynthesis of fatty acids. A genome-wide acetyl-CoA balance study showed ATP citrate lyase from Y. lipolytica as a robust source of cytoplasmic acetyl-CoA and malate synthase as a desirable target for down-regulation in terms of acetyl-CoA consumption. These genetic modifications were applied to S. cerevisiae WRY2, a strain that is capable of producing 460 mg L of free fatty acids. With the addition of ATP citrate lyase and down-regulation of malate synthase the engineered strain produced 26 per cent more free fatty acids. Further increases in free fatty acid production of 33 per cent were obtained by knocking out the cytoplasmic glycerol-3-phosphate dehydrogenase, which flux analysis had shown was competing for carbon flux upstream with the carbon flux through the acetyl-CoA production pathway in the cytoplasm. In total, the genetic interventions applied in this work increased fatty acid production by 70 per cent.

  7. Intracellular metabolite profiling of Saccharomyces cerevisiae evolved under furfural

    Jung, Young Hoon; Kim, Sooah; Yang, Jungwoo; Seo, Jin?Ho; Kim, Kyoung Heon

    2016-01-01

    Summary 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 y...

  8. Sucrose fermentation by Saccharomyces cerevisiae lacking hexose transport.

    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.

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

    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.

  10. Phylogenetic and genome-wide deep-sequencing analyses of canine parvovirus reveal co-infection with field variants and emergence of a recent recombinant strain.

    Ruben Pérez

    Full Text Available Canine parvovirus (CPV, a fast-evolving single-stranded DNA virus, comprises three antigenic variants (2a, 2b, and 2c with different frequencies and genetic variability among countries. The contribution of co-infection and recombination to the genetic variability of CPV is far from being fully elucidated. Here we took advantage of a natural CPV population, recently formed by the convergence of divergent CPV-2c and CPV-2a strains, to study co-infection and recombination. Complete sequences of the viral coding region of CPV-2a and CPV-2c strains from 40 samples were generated and analyzed using phylogenetic tools. Two samples showed co-infection and were further analyzed by deep sequencing. The sequence profile of one of the samples revealed the presence of CPV-2c and CPV-2a strains that differed at 29 nucleotides. The other sample included a minor CPV-2a strain (13.3% of the viral population and a major recombinant strain (86.7%. The recombinant strain arose from inter-genotypic recombination between CPV-2c and CPV-2a strains within the VP1/VP2 gene boundary. Our findings highlight the importance of deep-sequencing analysis to provide a better understanding of CPV molecular diversity.

  11. Phylogenetic and Genome-Wide Deep-Sequencing Analyses of Canine Parvovirus Reveal Co-Infection with Field Variants and Emergence of a Recent Recombinant Strain

    Pérez, Ruben; Calleros, Lucía; Marandino, Ana; Sarute, Nicolás; Iraola, Gregorio; Grecco, Sofia; Blanc, Hervé; Vignuzzi, Marco; Isakov, Ofer; Shomron, Noam; Carrau, Lucía; Hernández, Martín; Francia, Lourdes; Sosa, Katia; Tomás, Gonzalo; Panzera, Yanina

    2014-01-01

    Canine parvovirus (CPV), a fast-evolving single-stranded DNA virus, comprises three antigenic variants (2a, 2b, and 2c) with different frequencies and genetic variability among countries. The contribution of co-infection and recombination to the genetic variability of CPV is far from being fully elucidated. Here we took advantage of a natural CPV population, recently formed by the convergence of divergent CPV-2c and CPV-2a strains, to study co-infection and recombination. Complete sequences of the viral coding region of CPV-2a and CPV-2c strains from 40 samples were generated and analyzed using phylogenetic tools. Two samples showed co-infection and were further analyzed by deep sequencing. The sequence profile of one of the samples revealed the presence of CPV-2c and CPV-2a strains that differed at 29 nucleotides. The other sample included a minor CPV-2a strain (13.3% of the viral population) and a major recombinant strain (86.7%). The recombinant strain arose from inter-genotypic recombination between CPV-2c and CPV-2a strains within the VP1/VP2 gene boundary. Our findings highlight the importance of deep-sequencing analysis to provide a better understanding of CPV molecular diversity. PMID:25365348

  12. Lactose fermentation by engineered Saccharomyces cerevisiae capable of fermenting cellobiose.

    Liu, Jing-Jing; Zhang, Guo-Chang; Oh, Eun Joong; Pathanibul, Panchalee; Turner, Timothy L; Jin, Yong-Su

    2016-09-20

    Lactose is an inevitable byproduct of the dairy industry. In addition to cheese manufacturing, the growing Greek yogurt industry generates excess acid whey, which contains lactose. Therefore, rapid and efficient conversion of lactose to fuels and chemicals would be useful for recycling the otherwise harmful acid whey. Saccharomyces cerevisiae, a popular metabolic engineering host, cannot natively utilize lactose. However, we discovered that an engineered S. cerevisiae strain (EJ2) capable of fermenting cellobiose can also ferment lactose. This finding suggests that a cellobiose transporter (CDT-1) can transport lactose and a β-glucosidase (GH1-1) can hydrolyze lactose by acting as a β-galactosidase. While the lactose fermentation by the EJ2 strain was much slower than the cellobiose fermentation, a faster lactose-fermenting strain (EJ2e8) was obtained through serial subcultures on lactose. The EJ2e8 strain fermented lactose with a consumption rate of 2.16g/Lh. The improved lactose fermentation by the EJ2e8 strain was due to the increased copy number of cdt-1 and gh1-1 genes. Looking ahead, the EJ2e8 strain could be exploited for the production of other non-ethanol fuels and chemicals from lactose through further metabolic engineering. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    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.

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

    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.

  15. Yield and strength properties of the Ti-6-22-22S alloy over a wide strain rate and temperature range

    Krueger, L.; Kanel, G.I.; Razorenov, S.V.; Bezrouchko, G.S.; Meyer, L.

    2002-01-01

    A mechanical behavior of the Ti-6-22-22S alloy was studied under uniaxial strain conditions at shock-wave loading and under uniaxial compressive stress conditions over a strain rate range of 10-4 s-1 to 103 s-1. The test temperature was varied from -175 deg. C to 620 deg. C. The strain-rate and the temperature dependencies of the yield stress obtained from the uniaxial stress tests and from the shock-wave experiments are in a good agreement and demonstrate a significant decrease in the yield strength as the temperature increases. This indicates the thermal activation mechanism of plastic deformation of the alloy is maintained at strain rates up to 106 s-1. Variation of sample thickness from 2.24 to 10 mm results in relatively small variations in the dynamic yield strength and the spall strength over the whole temperature range

  16. 21 CFR 866.5785 - Anti-Saccharomyces cerevisiae (S. cerevisiae) antibody (ASCA) test systems.

    2010-04-01

    ...) antibody (ASCA) test systems. 866.5785 Section 866.5785 Food and Drugs FOOD AND DRUG ADMINISTRATION... Immunological Test Systems § 866.5785 Anti-Saccharomyces cerevisiae (S. cerevisiae) antibody (ASCA) test systems. (a) Identification. The Anti-Saccharomyces cerevisiae (S. cerevisiae) antibody (ASCA) test system is...

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

    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.

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

    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.

  19. Pathways of ultraviolet mutability in Saccharomyces cerevisiae

    Lemontt, J.F.

    1977-01-01

    Non-allelic mutants of Saccharomyces cerevisiae with reduced capacity for ultraviolet light (UV)-induced forward mutation from CAN1 to can1 were assigned to seven distinct genetic loci, each with allele designations umr1-1, umr2-1, ..., umr7-1 to indicate UV mutation resistance. None conferred a great deal of UV sensitivity. When assayed on yeast extract-peptone-dextrose complex growth agar, umr1, umr3, and umr7 were the most UV-sensitive. When assayed on synthetic agar lacking arginine, however, umr3 was the most UV-sensitive. All strains carrying each of the seven umr genes exhibited varying degrees of defective UV mutability, compact with wild types. Normal UV revertibility of three different alleles was observed in strains carrying either umr4, umr5, umr6, or umr7. Five a/α homozygous umr diploids failed to sporulate. One of these, umr7, blocked normal secretion of alpha hormone in α segregants and could not conjugate with a strains. The phenotypes of umr mutants are consistent with the existence of branched UV mutation pathways of different specificity

  20. Investigation of heart proteome of different consomic mouse strains. Testing the effect of polymorphisms on the proteome-wide trans-variation of proteins

    Stefanie Forler

    2015-06-01

    Full Text Available We investigated to which extent polymorphisms of an individual affect the proteomic network. Consomic mouse strains (CS were used to study the trans-effect of the cis-variant (polymorphic proteins of the strain PWD/Ph on the proteins of the host strain C57BL/6J. The cardiac proteome of ten CSs was analyzed by 2-DE and MS. Cis-variant PWD proteins altered a high number of C57BL/6J proteins, but the number of trans-variant proteins differed considerably between different CSs. Cardiac hypertrophy was induced in CSs. We found that high variability of the proteome, as induced by polymorphisms in CS14, acts protective against the complex disease.

  1. Copper Tolerance and Biosorption of Saccharomyces cerevisiae during Alcoholic Fermentation

    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

  2. Copper Tolerance and Biosorption of Saccharomyces cerevisiae during Alcoholic Fermentation.

    Xiang-Yu Sun

    Full Text Available 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.

  3. Numerical simulation of the mechanical behavior of ultrafine- and coarse-grained Zr-Nb alloys over a wide range of strain rates

    Serbenta, V. A.; Skripnyak, N. V.; Skripnyak, V. A.; Skripnyak, E. G.

    2017-12-01

    This paper presents the results on the development of theoretical methods of evaluation and prediction of mechanical properties of Zr-Nb alloys over a range of strain rates from 10-3 to 103 s-1. The mechanical behavior of coarse- and ultrafine-grained Zr-1Nb (E110) was investigated numerically. The ranges of strain rates and temperatures in which the mechanical behavior of Zr-1Nb alloy can be described using modified models of Johnson-Cook and Zerilli-Armstrong were defined. The results can be used in engineering analysis of designed technical systems for nuclear reactors.

  4. Removal of Pyrimethanil and Fenhexamid from Saccharomyces cerevisiae Liquid Cultures

    Etjen Bizaj

    2011-01-01

    Full Text Available The capacity for the removal of pyrimethanil and fenhexamid, two fungicides commonly used for the control of Botrytis cinerea in vineyards, has been evaluated during an alcoholic fermentation process in batch system. Commercial and wild strains of Saccharomyces cerevisiae were used. Batch fermentations were carried out in yeast extract-malt extract medium (YM with 18.0 % (by mass glucose, and the fungicides were added separately at three concentrations: 0.1, 1.0 and 10.0 mg/L. The removal capacity of yeast strains was also examined in stationary phase cultures of Saccharomyces cerevisiae. Stationary assays were performed with yeast biomass harvested from the stationary phase of an anaerobic fermentation process, with separate additions of 0.1, 1.0 and 10.0 mg/L of both fungicides. Removal studies with stationary phase cells were performed with viable and non-viable cells inactivated with sodium azide. This study clearly shows that both Saccharomyces cerevisiae strains were able to remove fenhexamid and pyrimethanil in stationary and fermentative assays. The removal potential is shown to be strain dependent in stationary but not in fermentative assays. However, the removal potential is dependent on the type of fungicide in both stationary and fermentative assays. In stationary phase cultures no significant difference in fungicide removal potential between viable and non-viable cells was observed, indicating that both pesticides were not degraded by metabolically active cells. However, the presence of both pesticides influenced fermentation kinetics and only pyrimethanil at 10.0 mg/L increased the production of volatile acidity of both strains.

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

    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. Improvement of Lead Tolerance of Saccharomyces cerevisiae by Random Mutagenesis of Transcription Regulator SPT3.

    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.

  7. Genome Dynamics of Hybrid Saccharomyces cerevisiae During Vegetative and Meiotic Divisions

    Abhishek Dutta

    2017-11-01

    Full Text Available Mutation and recombination are the major sources of genetic diversity in all organisms. In the baker’s yeast, all mutation rate estimates are in homozygous background. We determined the extent of genetic change through mutation and loss of heterozygosity (LOH in a heterozygous Saccharomyces cerevisiae genome during successive vegetative and meiotic divisions. We measured genome-wide LOH and base mutation rates during vegetative and meiotic divisions in a hybrid (S288c/YJM789 S. cerevisiae strain. The S288c/YJM789 hybrid showed nearly complete reduction in heterozygosity within 31 generations of meioses and improved spore viability. LOH in the meiotic lines was driven primarily by the mating of spores within the tetrad. The S288c/YJM789 hybrid lines propagated vegetatively for the same duration as the meiotic lines, showed variable LOH (from 2 to 3% and up to 35%. Two of the vegetative lines with extensive LOH showed frequent and large internal LOH tracts that suggest a high frequency of recombination repair. These results suggest significant LOH can occur in the S288c/YJM789 hybrid during vegetative propagation presumably due to return to growth events. The average base substitution rates for the vegetative lines (1.82 × 10−10 per base per division and the meiotic lines (1.22 × 10−10 per base per division are the first genome-wide mutation rate estimates for a hybrid yeast. This study therefore provides a novel context for the analysis of mutation rates (especially in the context of detecting LOH during vegetative divisions, compared to previous mutation accumulation studies in yeast that used homozygous backgrounds.

  8. Genome-wide analytical approaches for reverse metabolic engineering of industrially relevant phenotypes in yeast.

    Oud, Bart; van Maris, Antonius J A; Daran, Jean-Marc; Pronk, Jack T

    2012-03-01

    Successful reverse engineering of mutants that have been obtained by nontargeted strain improvement has long presented a major challenge in yeast biotechnology. This paper reviews the use of genome-wide approaches for analysis of Saccharomyces cerevisiae strains originating from evolutionary engineering or random mutagenesis. On the basis of an evaluation of the strengths and weaknesses of different methods, we conclude that for the initial identification of relevant genetic changes, whole genome sequencing is superior to other analytical techniques, such as transcriptome, metabolome, proteome, or array-based genome analysis. Key advantages of this technique over gene expression analysis include the independency of genome sequences on experimental context and the possibility to directly and precisely reproduce the identified changes in naive strains. The predictive value of genome-wide analysis of strains with industrially relevant characteristics can be further improved by classical genetics or simultaneous analysis of strains derived from parallel, independent strain improvement lineages. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  9. Fungal Screening on Olive Oil for Extracellular Triacylglycerol Lipases: Selection of a Trichoderma harzianum Strain and Genome Wide Search for the Genes

    Canseco-Pérez, Miguel Angel; Castillo-Avila, Genny Margarita; Islas-Flores, Ignacio; Apolinar-Hernández, Max M.; Rivera-Muñoz, Gerardo; Gamboa-Angulo, Marcela; Couoh-Uicab, Yeny

    2018-01-01

    A lipolytic screening with fungal strains isolated from lignocellulosic waste collected in banana plantation dumps was carried out. A Trichoderma harzianum strain (B13-1) showed good extracellular lipolytic activity (205 UmL−1). Subsequently, functional screening of the lipolytic activity on Rhodamine B enriched with olive oil as the only carbon source was performed. The successful growth of the strain allows us to suggest that a true lipase is responsible for the lipolytic activity in the B13-1 strain. In order to identify the gene(s) encoding the protein responsible for the lipolytic activity, in silico identification and characterization of triacylglycerol lipases from T. harzianum is reported for the first time. A survey in the genome of this fungus retrieved 50 lipases; however, bioinformatic analyses and putative functional descriptions in different databases allowed us to choose seven lipases as candidates. Suitability of the bioinformatic screening to select the candidates was confirmed by reverse transcription polymerase chain reaction (RT-PCR). The gene codifying 526309 was expressed when the fungus grew in a medium with olive oil as carbon source. This protein shares homology with commercial lipases, making it a candidate for further applications. The success in identifying a lipase gene inducible with olive oil and the suitability of the functional screening and bioinformatic survey carried out herein, support the premise that the strategy can be used in other microorganisms with sequenced genomes to search for true lipases, or other enzymes belonging to large protein families. PMID:29370083

  10. Thermomechanical response of 3D laser-deposited Ti–6Al–4V alloy over a wide range of strain rates and temperatures

    Li, Peng-Hui [School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072 (China); Guo, Wei-Guo, E-mail: weiguo@nwpu.edu.cn [School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072 (China); Huang, Wei-Dong [The State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Su, Yu [Department of Mechanics, School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China); Lin, Xin [The State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Yuan, Kang-Bo [School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072 (China)

    2015-10-28

    To understand and evaluate the thermomechanical property of Ti–6Al–4V alloy prepared by the 3D laser deposition technology, an uniaxial compression test was performed on cylindrical samples using an electronic universal testing machine and enhanced Hopkinson technique, over the range of strain rate from 0.001/s to 5000/s, and at initial temperatures from the room temperature to 1173 K. The microstructure of the undeformed and deformed samples was examined through optical microscopy and the use of scanning electron microscope (SEM). The experimental results show the followings: (1) the anisotropy of the mechanical property of this alloy is not significant despite the visible stratification at the exterior surfaces; (2) initial defects, such as the initial voids and lack of fusion, are found in the microstructure and in the crack surfaces of the deformed samples, and they are considered as a major source of crack initiation and propagation; (3) adiabatic shear bands and shearing can easily develop at all selected temperatures for samples under compression; (4) the yield and ultimate strengths of this laser-deposited Ti–6Al–4V alloy are both lower than those of the Ti–6Al–4V alloy prepared by forging and electron beam melting, whereas both of its strengths are higher than those of a conventional grade Ti–6Al–4V alloy at high strain rate only. In addition to compression tests we also conducted tensile loading tests on the laser-deposited alloy at both low and high strain rates (0.1/s and 1000/s). There is significant tension/compression asymmetry in the mechanical response under high-strain-rate loading. It was found that the quasi-static tensile fracturing exhibits typical composite fracture characteristic with quasi-cleavages and dimples, while the high-strain-rate fracturing is characterized by ductile fracture behavior.

  11. Modelling of Ethanol Production from Red Beet Juice by Saccharomyces cerevisiae under Thermal and Acid Stress Conditions

    Donaji Jiménez-Islas

    2014-01-01

    Full Text Available In this work the effects of pH and temperature on ethanol production from red beet juice by the strains Saccharomyces cerevisiae ITD00196 and S. cerevisiae ATCC 9763 are studied. Logistic, Pirt, and Luedeking-Piret equations were used to describe quantitatively the microbial growth, substrate consumption, and ethanol production, respectively. The two S. cerevisiae strains used in this study were able to produce ethanol with high yield and volumetric productivity under acid and thermal stress conditions. The equations used to model the fermentation kinetics fit very well with the experimental data, thus establishing that ethanol production was growth associated under the evaluated conditions. The yeast S. cerevisiae ITD00196 had the best fermentative capacity and could be considered as an interesting option to develop bioprocesses for ethanol production.

  12. ACTIVITY OF SUPEROXIDE DISMUTASE ENZYME IN YEAST SACCHAROMYCES CEREVISIAE

    Blažena Lavová

    2014-02-01

    Full Text Available Reactive oxygen species (ROS with reactive nitrogen species (RNS are known to play dual role in biological systems, they can be harmful or beneficial to living systems. ROS can be important mediators of damage to cell structures, including proteins, lipids and nucleic acids termed as oxidative stress. The antioxidant enzymes protect the organism against the oxidative damage caused by active oxygen forms. The role of superoxide dismutase (SOD is to accelerate the dismutation of the toxic superoxide radical, produced during oxidative energy processes, to hydrogen peroxide and molecular oxygen. In this study, SOD activity of three yeast strains Saccharomyces cerevisiae was determined. It was found that SOD activity was the highest (23.7 U.mg-1 protein in strain 612 after 28 hours of cultivation. The lowest SOD activity from all tested strains was found after 56 hours of cultivation of strain Gyöng (0.7 U.mg-1 protein.

  13. Molecular - and genetic aspects of the repair of the lesions induced by the furocoumarin photoaddition in Sacharomyces cerevisiae : role of the PSO genes

    Henriques, J.A.P.

    1982-01-01

    Experiences with strains of Sacharomyces cerevisiae with the aim to obtain informations about molecular steps and genetic control of the DNA photo-induced lesion repair by furocoumarins are described. (M.A.) [pt

  14. Breeding of lager yeast with Saccharomyces cerevisiae improves stress resistance and fermentation performance.

    Garcia Sanchez, Rosa; Solodovnikova, Natalia; Wendland, Jürgen

    2012-08-01

    Lager beer brewing relies on strains collectively known as Saccharomyces carlsbergensis, which are hybrids between S. cerevisiae and S. eubayanus-like strains. Lager yeasts are particularly adapted to low-temperature fermentations. Selection of new yeast strains for improved traits or fermentation performance is laborious, due to the allotetraploid nature of lager yeasts. Initially, we have generated new F1 hybrids by classical genetics, using spore clones of lager yeast and S. cerevisiae and complementation of auxotrophies of the single strains upon mating. These hybrids were improved on several parameters, including growth at elevated temperature and resistance against high osmolarity or high ethanol concentrations. Due to the uncertainty of chromosomal make-up of lager yeast spore clones, we introduced molecular markers to analyse mating-type composition by PCR. Based on these results, new hybrids between a lager and an ale yeast strain were isolated by micromanipulation. These hybrids were not subject to genetic modification. We generated and verified 13 hybrid strains. All of these hybrid strains showed improved stress resistance as seen in the ale parent, including improved survival at the end of fermentation. Importantly, some of the strains showed improved fermentation rates using 18° Plato at 18-25°C. Uniparental mitochondrial DNA inheritance was observed mostly from the S. cerevisiae parent. Copyright © 2012 John Wiley & Sons, Ltd.

  15. Saccharomyces cerevisiae: a sexy yeast with a prion problem.

    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.

  16. Increasing cocoa butter-like lipid production of Saccharomyces cerevisiae by expression of selected cocoa genes

    Wei, Yongjun; Gossing, Michael; Bergenholm, David

    2017-01-01

    for CB biosynthesis from the cocoa genome using a phylogenetic analysis approach. By expressing the selected cocoa genes in S. cerevisiae, we successfully increased total fatty acid production, TAG production and CBL production in some S. cerevisiae strains. The relative CBL content in three yeast...... higher level of CBL compared with the control strain. In summary, CBL production by S. cerevisiae were increased through expressing selected cocoa genes potentially involved in CB biosynthesis.......Cocoa butter (CB) extracted from cocoa beans mainly consists of three different kinds of triacylglycerols (TAGs), 1,3-dipalmitoyl-2-oleoyl-glycerol (POP, C16:0-C18:1-C16:0), 1-palmitoyl-3-stearoyl-2-oleoyl-glycerol(POS,C16:0C18:1-C18:0) and 1,3-distearoyl-2-oleoyl-glycerol (SOS, C18:0-C18:1-C18...

  17. Complete genomic and transcriptional landscape analysis using third-generation sequencing: a case study of Saccharomyces cerevisiae CEN.PK113-7D

    Jenjaroenpun, Piroon; Wongsurawat, Thidathip; Pereira, Rui

    2018-01-01

    Completion of eukaryal genomes can be difficult task with the highly repetitive sequences along the chromosomes and short read lengths of secondgeneration sequencing. Saccharomyces cerevisiae strain CEN. PK113-7D, widely used as a model organism and a cell factory, was selected for this study...... to demonstrate the superior capability of very long sequence reads for de novo genome assembly. We generated long reads using two common third-generation sequencing technologies (Oxford Nanopore Technology (ONT) and Pacific Biosciences (PacBio)) and used short reads obtained using Illumina sequencing for error...... correction. Assembly of the reads derived from all three technologies resulted in complete sequences for all 16 yeast chromosomes, as well as themitochondrial chromosome, in one step. Further, we identified three types of DNA methylation (5mC, 4mC and 6mA). Comparison between the reference strain S288C...

  18. Comparison of heterologous xylose transporters in recombinant Saccharomyces cerevisiae

    Hahn-Hägerdal Bärbel

    2010-03-01

    Full Text Available Abstract Background Baker's yeast (Saccharomyces cerevisiae has been engineered for xylose utilization to enable production of fuel ethanol from lignocellulose raw material. One unresolved challenge is that S. cerevisiae lacks a dedicated transport system for pentose sugars, which means that xylose is transported by non-specific Hxt transporters with comparatively low transport rate and affinity for xylose. Results In this study, we compared three heterologous xylose transporters that have recently been shown to improve xylose uptake under different experimental conditions. The transporters Gxf1, Sut1 and At5g59250 from Candida intermedia, Pichia stipitis and Arabidopsis thaliana, respectively, were expressed in isogenic strains of S. cerevisiae and the transport kinetics and utilization of xylose was evaluated. Expression of the Gxf1 and Sut1 transporters led to significantly increased affinity and transport rates of xylose. In batch cultivation at 4 g/L xylose concentration, improved transport kinetics led to a corresponding increase in xylose utilization, whereas no correlation could be demonstrated at xylose concentrations greater than 15 g/L. The relative contribution of native sugar transporters to the overall xylose transport capacity was also estimated during growth on glucose and xylose. Conclusions Kinetic characterization and aerobic batch cultivation of strains expressing the Gxf1, Sut1 and At5g59250 transporters showed a direct relationship between transport kinetics and xylose growth. The Gxf1 transporter had the highest transport capacity and the highest xylose growth rate, followed by the Sut1 transporter. The range in which transport controlled the growth rate was determined to between 0 and 15 g/L xylose. The role of catabolite repression in regulation of native transporters was also confirmed by the observation that xylose transport by native S. cerevisiae transporters increased significantly during cultivation in xylose and

  19. levadura Saccharomyces Cerevisiae

    B. Aguilar Uscanga

    2005-01-01

    Full Text Available La pared celular de levaduras representa entre 20 a 30 % de la célula en peso seco. Está compuesta de polisacáridos complejos de β-glucanos, manoproteínas y quitina. Se estudió la composición de los polisacáridos contenidos en la pared celular de la Saccharomyces cerevisiae CEN.PK 113 y se observó el efecto de la variación de la fuente carbono (glucosa, sacarosa, galactosa, maltosa, manosa, etanol y pH (3, 4, 5, 6 en un medio mineral “cell factory”. Las células fueron recolectadas en fase exponencial y se extrajo la pared celular. Los extractos de pared se hidrolizaron con H2SO4 al 72% y las muestras fueron analizadas por cromatografía HPLC. Se realizó una prueba de resistencia al rompimiento celular con una β(1,3-glucanasa, y las células cultivadas a diferentes fuentes carbono y pH. Los resultados del análisis por HPLC, mostraron que la composición de los polisacáridos en la pared celular, varía considerablemente con las modificaciones del medio de cultivo. Se observó que las levaduras cultivadas en sacarosa tienen mayor porcentaje de pared celular (25% y mayor cantidad de glucanos (115µg/mg peso seco y mananos (131µg/mg peso seco, que aquellas levaduras cultivadas en etanol (13% en peso seco. Las levaduras cultivadas a pH 5 presentaron 19% de pared celular en peso seco, mientras que a pH 6 el porcentaje fue menor (14%. El análisis de resistencia al rompimiento celular, mostró que las células cultivadas en etanol y galactosa fueron resistentes al rompimiento enzimático. Se comparó este resultado con el contenido de polisacáridos en la pared celular y concluimos que la resistencia de la célula al rompimiento, no está ligada con la cantidad de β-glucanos contenidos en la pared celular, sino que va a depender del número de enlaces β(1,3 y β(1,6-glucanos, los cuales juegan un rol importante durante el ensamblaje de la pared

  20. Saccharomyces cerevisiae from Brazilian kefir-fermented milk: An in vitro evaluation of probiotic properties.

    Lima, Meire Dos Santos Falcão de; Souza, Karoline Mirella Soares de; Albuquerque, Wendell Wagner Campos; Teixeira, José António Couto; Cavalcanti, Maria Taciana Holanda; Porto, Ana Lúcia Figueiredo

    2017-09-01

    The therapeutic use of probiotics for supporting the antibiotic action against gastrointestinal disorders is a current trend and emerging applications have gained popularity because of their support for various microbiological activities in digestive processes. Microorganisms isolated from kefir with great probiotic properties, in addition to high resistance to harsh environmental conditions, have been widely researched. Administration of probiotic yeasts offers a number of advantages, when compared to bacteria, because of particular characteristics as their larger cell size. In the present study, 28 strains of Saccharomyces cerevisiae were isolated, after in vitro digestion of kefir-fermented milk, and identified by molecular based approaches. A screening was performed to determine important quality requirements for probiotics including: antagonistic and antioxidant activities, β-galactosidase synthesis, autoaggregation, surface hydrophobicity and adhesion to epithelial cells. The results showed strains: with antagonistic activity against microbial pathogens such as Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis; able to produce β-galactosidase; with antioxidant activity levels higher than 90%; with hydrophobicity activity and autoaggregation ability (evaluated by adhesion test, where all the strains presented adhesion to mice ileal epithelial cells). These findings are relevant and the strains are recommended for further in vivo studies as well as for potential therapeutic applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. The impact of respiration and oxidative stress response on recombinant α-amylase production by Saccharomyces cerevisiae

    Martinez Ruiz, José Luis; Meza, Eugenio; Petranovic, Dina

    2016-01-01

    by overexpressing the endogenous HAP1 gene in a S. cerevisiae strain overproducing recombinant α-amylase. We demonstrate how Hap1p can activate a set of oxidative stress response genes and meanwhile contribute to increase the metabolic rate of the yeast strains, therefore mitigating the negative effect of the ROS...

  2. CRISPR/Cas9 : A molecular Swiss army knife for simultaneous introduction of multiple genetic modifications in Saccharomyces cerevisiae

    Mans, R.; Van Rossum, H.M.; Wijsman, M.; Backx, A.; Kuijpers, N.G.A.; van den Broek, M.; Daran-Lapujade, P.A.S.; Pronk, J.T.; Van Maris, A.J.A.; Daran, J.G.

    2015-01-01

    A variety of techniques for strain engineering in Saccharomyces cerevisiae have recently been developed. However, especially when multiple genetic manipulations are required, strain construction is still a time-consuming process. This study describes new CRISPR/Cas9-based approaches for easy, fast

  3. Adaptive Response and Tolerance to Acetic Acid in Saccharomyces cerevisiae and Zygosaccharomyces bailii: A Physiological Genomics Perspective.

    Palma, Margarida; Guerreiro, Joana F; Sá-Correia, Isabel

    2018-01-01

    Acetic acid is an important microbial growth inhibitor in the food industry; it is used as a preservative in foods and beverages and is produced during normal yeast metabolism in biotechnological processes. Acetic acid is also a major inhibitory compound present in lignocellulosic hydrolysates affecting the use of this promising carbon source for sustainable bioprocesses. Although the molecular mechanisms underlying Saccharomyces cerevisiae response and adaptation to acetic acid have been studied for years, only recently they have been examined in more detail in Zygosaccharomyces bailii . However, due to its remarkable tolerance to acetic acid and other weak acids this yeast species is a major threat in the spoilage of acidic foods and beverages and considered as an interesting alternative cell factory in Biotechnology. This review paper emphasizes genome-wide strategies that are providing global insights into the molecular targets, signaling pathways and mechanisms behind S. cerevisiae and Z. bailii tolerance to acetic acid, and extends this information to other weak acids whenever relevant. Such comprehensive perspective and the knowledge gathered in these two yeast species allowed the identification of candidate molecular targets, either for the design of effective strategies to overcome yeast spoilage in acidic foods and beverages, or for the rational genome engineering to construct more robust industrial strains. Examples of successful applications are provided.

  4. Investigating the underlying mechanism of Saccharomyces cerevisiae in response to ethanol stress employing RNA-seq analysis.

    Li, Ruoyun; Xiong, Guotong; Yuan, Shukun; Wu, Zufang; Miao, Yingjie; Weng, Peifang

    2017-11-03

    Saccharomyces cerevisiae has been widely used for wine fermentation and bio-fuels production. A S. cerevisiae strain Sc131 isolated from tropical fruit shows good fermentation properties and ethanol tolerance, exhibiting significant potential in Chinese bayberry wine fermentation. In this study, RNA-sequence and RT-qPCR was used to investigate the transcriptome profile of Sc131 in response to ethanol stress. Scanning Electron Microscopy were carried out to observe surface morphology of yeast cells. Totally, 937 genes were identified differential expressed, including 587 up-regulated and 350 down-regulated genes, after 4-h ethanol stress (10% v/v). Transcriptomic analysis revealed that, most genes involved in regulating filamentous growth or pseudohyphal growth were significantly up-regulated in response to ethanol stress. The complex protein quality control machineries, Hsp90/Hsp70 and Hsp104/Hsp70/Hsp40 based chaperone system combining with ubiquitin-proteasome proteolytic pathway were both activated to recognize and degrade misfolding proteins. Genes related to biosynthesis and metabolism of two well-known stress-responsive substances trehalose and ergosterol were generally up-regulated, while genes associated with amino acids biosynthesis and metabolism processes were differentially expressed. Moreover, thiamine was also important in response to ethanol stress. This research may promote the potential applications of Sc131 in the fermentation of Chinese bayberry wine.

  5. Molecular Basis for Saccharomyces cerevisiae Biofilm Development

    Andersen, Kaj Scherz

    In this study, I sought to identify genes regulating the global molecular program for development of sessile multicellular communities, also known as biofilm, of the eukaryotic microorganism, Saccharomyces cerevisiae (yeast). Yeast biofilm has a clinical interest, as biofilms can cause chronic...... infections in humans. Biofilm is also interesting from an evolutionary standpoint, as an example of primitive multicellularity. By using a genome-wide screen of yeast deletion mutants, I show that 71 genes are essential for biofilm formation. Two-thirds of these genes are required for transcription of FLO11......, but only a small subset is previously described as regulators of FLO11. These results reveal that the regulation of biofilm formation and FLO11 is even more complex than what has previously been described. I find that the molecular program for biofilm formation shares many essential components with two...

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

    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.

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

    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

  8. In vivo dynamics of galactose metabolism in Saccharomyces cerevisiae: Metabolic fluxes and metabolite levels

    Østergaard, Simon; Olsson, Lisbeth; Nielsen, Jens

    2001-01-01

    The dynamics of galactose metabolism in Saccharomyces cerevisiae was studied by analyzing the metabolic response of the CEN.PK 113-7D wild-type strain when exposed to a galactose pulse during aerobic growth in a galactose-limited steady-state cultivation at a dilution rate of 0.097 h(-1). A fast...

  9. Engineering of Saccharomyces cerevisiae for Efficient Anaerobic Alcoholic Fermentation of L-Arabinose

    Wisselink, H.W.; Toirkens, M.J.; Del Rosario Franco Berriel, M.; Winkler, A.A.; Van Dijken, J.P.; Pronk, J.T.; Van Maris, A.J.A.

    2007-01-01

    For cost-effective and efficient ethanol production from lignocellulosic fractions of plant biomass, the conversion of not only major constituents, such as glucose and xylose, but also less predominant sugars, such as L-arabinose, is required. Wild-type strains of Saccharomyces cerevisiae, the

  10. Saccharomyces cerevisiae Mixed Culture of Blackberry (Rubus ulmifolius L.) Juice: Synergism in the Aroma Compounds Production

    Bautista-Rosales, Pedro Ulises; Ragazzo-Sánchez, Juan Arturo; Ruiz-Montañez, Gabriela; Ortiz-Basurto, Rosa Isela; Luna-Solano, Guadalupe; Calderón-Santoyo, Montserrat

    2014-01-01

    Blackberry (Rubus sp.) juice was fermented using four different strains of Saccharomyces cerevisiae (Vitilevure-CM4457, Enoferm-T306, ICV-K1, and Greroche Rhona-L3574) recognized because of their use in the wine industry. A medium alcoholic graduation spirit (

  11. Increased mannoprotein content in wines produced by Saccharomyces kudriavzevii×Saccharomyces cerevisiae hybrids.

    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.

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

    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.

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

    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.

  14. Expansion and contraction of the DUP240 multigene family in Saccharomyces cerevisiae populations.

    Leh-Louis, Véronique; Wirth, Bénédicte; Potier, Serge; Souciet, Jean-Luc; Despons, Laurence

    2004-01-01

    The influence of duplicated sequences on chromosomal stability is poorly understood. To characterize chromosomal rearrangements involving duplicated sequences, we compared the organization of tandem repeats of the DUP240 gene family in 15 Saccharomyces cerevisiae strains of various origins. The DUP240 gene family consists of 10 members of unknown function in the reference strain S288C. Five DUP240 paralogs on chromosome I and two on chromosome VII are arranged as tandem repeats that are highl...

  15. Methodology of investigation of the effect of ultrasonic oscillations on mechanical properties of structural materials in a wide range of temperatures and strain rates

    Bakay, S.O.; Gurin, V.A.; Gurin, I.V.; Neklyudov, I.M.; Gorbatenko, V.M.; Netesov, V.M.; Dub, S.N.

    2007-01-01

    The present message is devoted to the description of a method of research of influence of ultrasound on physicomechanical properties of constructional materials during plastic deformation in vacuum. The functional diagram and the description of created experimental facility which allows to carry out researches by this method is resulted. The created method and the equipment it has been approved for studying influence of ultrasound on physicomechanical properties of carbon composite materials of nuclear industry. Mechanical properties of carbon - carbon composite materials are investigated in a range of temperatures from room up to 600 degree C, at various strain rates, in conditions of ultrasonic vibrations and without them. The analysis of results received is carried out at use of a method of mechanical tests of samples of carbon before ultrasonic processing on nanohardness. The comparative estimation of the received experimental data is resulted

  16. Thermodynamic Properties, Hysteresis Behavior and Stress-Strain Analysis of MgH2 Thin Films, Studied over a Wide Temperature Range

    Yevheniy Pivak

    2012-06-01

    Full Text Available Using hydrogenography, we investigate the thermodynamic parameters and hysteresis behavior in Mg thin films capped by Ta/Pd, in a temperature range from 333 K to 545 K. The enthalpy and entropy of hydride decomposition, ∆Hdes = −78.3 kJ/molH2, ∆Sdes = −136.1 J/K molH2, estimated from the Van't Hoff analysis, are in good agreement with bulk results, while the absorption thermodynamics, ∆Habs = −61.6 kJ/molH2, ∆Sabs = −110.9 J/K molH2, appear to be substantially affected by the clamping of the film to the substrate. The clamping is negligible at high temperatures, T > 523 K, while at lower temperatures, T < 393 K, it is considerable. The hysteresis at room temperature in Mg/Ta/Pd films increases by a factor of 16 as compared to MgH2 bulk. The hysteresis increases even further in Mg/Pd films, most likely due to the formation of a Mg-Pd alloy at the Mg/Pd interface. The stress–strain analysis of the Mg/Ta/Pd films at 300–333 K proves that the increase of the hysteresis occurs due to additional mechanical work during the (de-hydrogenation cycle. With a proper temperature correction, our stress–strain analysis quantitatively and qualitatively explains the hysteresis behavior in thin films, as compared to bulk, over the whole temperature range.

  17. Saccharomyces cerevisiae in the Production of Fermented Beverages

    Graeme M Walker

    2016-11-01

    Full Text Available Alcoholic beverages are produced following the fermentation of sugars by yeasts, mainly (but not exclusively strains of the species, Saccharomyces cerevisiae. The sugary starting materials may emanate from cereal starches (which require enzymatic pre-hydrolysis in the case of beers and whiskies, sucrose-rich plants (molasses or sugar juice from sugarcane in the case of rums, or from fruits (which do not require pre-hydrolysis in the case of wines and brandies. In the presence of sugars, together with other essential nutrients such as amino acids, minerals and vitamins, S. cerevisiae will conduct fermentative metabolism to ethanol and carbon dioxide (as the primary fermentation metabolites as the cells strive to make energy and regenerate the coenzyme NAD+ under anaerobic conditions. Yeasts will also produce numerous secondary metabolites which act as important beverage flavour congeners, including higher alcohols, esters, carbonyls and sulphur compounds. These are very important in dictating the final flavour and aroma characteristics of beverages such as beer and wine, but also in distilled beverages such as whisky, rum and brandy. Therefore, yeasts are of vital importance in providing the alcohol content and the sensory profiles of such beverages. This Introductory Chapter reviews, in general, the growth, physiology and metabolism of S. cerevisiae in alcoholic beverage fermentations.

  18. Osmo-, thermo- and ethanol- tolerances of Saccharomyces cerevisiae S1

    Sandrasegarampillai Balakumar

    2012-03-01

    Full Text Available Saccharomyces cerevisiae S1, which is a locally isolated and improved strain showed viability at 40, 45 and 50ºC and produced ethanol at 40, 43 and 45ºC. When the cells were given heat shock at 45ºC for 30min and grown at 40ºC, 100% viability was observed for 60h, and addition of 200gl-1 ethanol has led to complete cell death at 30h. Heat shock given at 45ºC (for 30min has improved the tolerance to temperature induced ethanol shock leading to 37% viability at 30h. when the cells were subjected to ethanol (200gl-1 for 30 min and osmotic shock (sorbitol 300gl-1, trehalose contents in the cells were increased. The heat shocked cells showed better viability in presence of added ethanol. Soy flour supplementation has improved the viability of S. cerevisiae S1 to 80% in presence of 100gl-1 added ethanol and to 60% in presence of 300gl-1 sorbitol. In presence of sorbitol (200gl-1 and ethanol (50gl-1 at 40ºC, 46% viability was retained by S. cerevisiae S1 at 48h and it was improved to 80% by soy flour supplementation.

  19. Intracellular metabolite profiling of Saccharomyces cerevisiae evolved under furfural.

    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.

  20. Probiotic Activity of Saccharomyces cerevisiae var. boulardii Against Human Pathogens

    Katarzyna Rajkowska

    2012-01-01

    Full Text Available Infectious diarrhoea is associated with a modification of the intestinal microflora and colonization of pathogenic bacteria. Tests were performed for seven probiotic yeast strains of Saccharomyces cerevisiae var. boulardii, designated for the prevention and treatment of diarrhoea. To check their possible effectiveness against diarrhoea of different etiologies, the activity against a variety of human pathogenic or opportunistic bacteria was investigated in vitro. In mixed cultures with S. cerevisiae var. boulardii, a statistically significant reduction was observed in the number of cells of Listeria monocytogenes, Pseudomonas aeruginosa and Staphylococcus aureus, by even 55.9 % in the case of L. monocytogenes compared with bacterial monocultures. The influence of yeasts was mostly associated with the shortening of the bacterial lag phase duration, more rapid achievement of the maximum growth rates, and a decrease by 4.4–57.1 % (L. monocytogenes, P. aeruginosa, or an increase by 1.4–70.6 % (Escherichia coli, Enterococcus faecalis, Salmonella Typhimurium in the exponential growth rates. Another issue included in the research was the ability of S. cerevisiae var. boulardii to bind pathogenic bacteria to its cell surface. Yeasts have shown binding capacity of E. coli, S. Typhimurium and additionally of S. aureus, Campylobacter jejuni and E. faecalis. However, no adhesion of L. monocytogenes and P. aeruginosa to the yeast cell wall was noted. The probiotic activity of S. cerevisiae var. boulardii against human pathogens is related to a decrease in the number of viable and active cells of bacteria and the binding capacity of yeasts. These processes may limit bacterial invasiveness and prevent bacterial adherence and translocation in the human intestines.

  1. Genome wide discovery of long intergenic non-coding RNAs in Diamondback moth (Plutella xylostella) and their expression in insecticide resistant strains

    Etebari, Kayvan; Furlong, Michael J.; Asgari, Sassan

    2015-01-01

    Long non-coding RNAs (lncRNAs) play important roles in genomic imprinting, cancer, differentiation and regulation of gene expression. Here, we identified 3844 long intergenic ncRNAs (lincRNA) in Plutella xylostella, which is a notorious pest of cruciferous plants that has developed field resistance to all classes of insecticides, including Bacillus thuringiensis (Bt) endotoxins. Further, we found that some of those lincRNAs may potentially serve as precursors for the production of small ncRNAs. We found 280 and 350 lincRNAs that are differentially expressed in Chlorpyrifos and Fipronil resistant larvae. A survey on P. xylostella midgut transcriptome data from Bt-resistant populations revealed 59 altered lincRNA in two resistant strains compared with the susceptible population. We validated the transcript levels of a number of putative lincRNAs in deltamethrin-resistant larvae that were exposed to deltamethrin, which indicated that this group of lincRNAs might be involved in the response to xenobiotics in this insect. To functionally characterize DBM lincRNAs, gene ontology (GO) enrichment of their associated protein-coding genes was extracted and showed over representation of protein, DNA and RNA binding GO terms. The data presented here will facilitate future studies to unravel the function of lincRNAs in insecticide resistance or the response to xenobiotics of eukaryotic cells. PMID:26411386

  2. Effect of severe plastic deformation on microstructure and mechanical properties of magnesium and aluminium alloys in wide range of strain rates

    Skripnyak, Vladimir; Skripnyak, Evgeniya; Skripnyak, Vladimir; Vaganova, Irina; Skripnyak, Nataliya

    2013-06-01

    Results of researches testify that a grain size have a strong influence on the mechanical behavior of metals and alloys. Ultrafine grained HCP and FCC metal alloys present higher values of the spall strength than a corresponding coarse grained counterparts. In the present study we investigate the effect of grain size distribution on the flow stress and strength under dynamic compression and tension of aluminium and magnesium alloys. Microstructure and grain size distribution in alloys were varied by carrying out severe plastic deformation during the multiple-pass equal channel angular pressing, cyclic constrained groove pressing, and surface mechanical attrition treatment. Tests were performed using a VHS-Instron servo-hydraulic machine. Ultra high speed camera Phantom V710 was used for photo registration of deformation and fracture of specimens in range of strain rates from 0,01 to 1000 1/s. In dynamic regime UFG alloys exhibit a stronger decrease in ductility compared to the coarse grained material. The plastic flow of UFG alloys with a bimodal grain size distribution was highly localized. Shear bands and shear crack nucleation and growth were recorded using high speed photography.

  3. Dual utilization of NADPH and NADH cofactors enhances xylitol production in engineered Saccharomyces cerevisiae.

    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.

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

    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.

  5. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA); Scientific Opinion on the substantiation of a health claim related to Saccharomyces cerevisiae var. boulardii CNCM I-3799 and reducing gastrointestinal discomfort pursuant to Article 13(5) of Regulation (EC) No 1924/2006

    Tetens, Inge

    substantiation of a health claim related to Saccharomyces cerevisiae var. boulardii CNCM I-3799 and reducing gastro-intestinal discomfort. The food constituent that is the subject of the health claim, S. cerevisiae var. boulardii CNCM I-3799, is sufficiently characterised. The claimed effect, reduction of gastro....... cerevisiae var. boulardii CNCM I-3799), except for two animal studies and one in vitro study. Upon an EFSA request, the applicant indicated that the rest of the studies provided were conducted with the strain produced by Biocodex Laboratories (S. cerevisiae var. boulardii HANSEN CBS 5926). The applicant also...... stated that the strain, which is the subject of the claim, S. cerevisiae var. boulardii CNCM I-3799, is equivalent to S. cerevisiae var. boulardii HANSEN CBS 5926, based on a comparative PCR inter-delta element analysis of both strains provided in the application. The Panel considered that the evidence...

  6. Using Saccharomyces cerevisiae to test the mutagenicity of household compounds: an open ended hypothesis-driven teaching lab.

    Marshall, Pamela A

    2007-01-01

    In our Fundamentals of Genetics lab, students perform a wide variety of labs to reinforce and extend the topics covered in lecture. I developed an active-learning lab to augment the lecture topic of mutagenesis. In this lab exercise, students determine if a compound they bring from home is a mutagen. Students are required to read extensive background material, perform research to find a potential mutagen to test, develop a hypothesis, and bring to the lab their own suspected mutagen. This lab uses a specially developed strain of Saccharomyces cerevisiae, D7, to determine if a compound is a mutagen. Mutagenesis of the D7 genome can lead to a scorable alteration in the phenotypes of this strain. Students outline and carry out a protocol for treatment of the yeast tester strain, utilizing the concept of dose/response and positive and negative controls. Students report on their results using a PowerPoint presentation to simulate giving a scientific presentation. The students' self-assessment of their knowledge indicated that, in all cases, the students felt that they knew more about the assay, mutagenesis, and the relationship between genotype and phenotype (P exercise.

  7. Single-cell analysis of S. cerevisiae growth recovery after a sublethal heat-stress applied during an alcoholic fermentation.

    Tibayrenc, Pierre; Preziosi-Belloy, Laurence; Ghommidh, Charles

    2011-06-01

    Interest in bioethanol production has experienced a resurgence in the last few years. Poor temperature control in industrial fermentation tanks exposes the yeast cells used for this production to intermittent heat stress which impairs fermentation efficiency. Therefore, there is a need for yeast strains with improved tolerance, able to recover from such temperature variations. Accordingly, this paper reports the development of methods for the characterization of Saccharomyces cerevisiae growth recovery after a sublethal heat stress. Single-cell measurements were carried out in order to detect cell-to-cell variability. Alcoholic batch fermentations were performed on a defined medium in a 2 l instrumented bioreactor. A rapid temperature shift from 33 to 43 °C was applied when ethanol concentration reached 50 g l⁻¹. Samples were collected at different times after the temperature shift. Single cell growth capability, lag-time and initial growth rate were determined by monitoring the growth of a statistically significant number of cells after agar medium plating. The rapid temperature shift resulted in an immediate arrest of growth and triggered a progressive loss of cultivability from 100 to 0.0001% within 8 h. Heat-injured cells were able to recover their growth capability on agar medium after a lag phase. Lag-time was longer and more widely distributed as the time of heat exposure increased. Thus, lag-time distribution gives an insight into strain sensitivity to heat-stress, and could be helpful for the selection of yeast strains of technological interest.

  8. Toxicity of isoproturon on Saccharomyces cerevisiae growing in mineral medium depends on glutathione-mediated antioxidant capacity.

    Candeias, M; Alves-Pereira, I; Ferreira, Rui

    2011-01-01

    The results revealed an increase of viable cells, after 72 h of culture and an increase of antioxidant power mediated by GSH and GR activity in S. cerevisiae UE-ME3. The adaptive response of UE-ME3 strain to isoproturon, determined in MB, was clearly higher than observed in IGC-3507 strain. So, we presume that the extent of the toxic effect of isoproturon in both yeast strains depends on glutathione-mediated antioxidant capacity.

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

    Borodina, Irina; Nielsen, Jens

    2014-01-01

    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 deve......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...

  10. Systems Biology of Saccharomyces cerevisiae Physiology and its DNA Damage Response

    Fazio, Alessandro

    The yeast Saccharomyces cerevisiae is a model organism in biology, being widely used in fundamental research, the first eukaryotic organism to be fully sequenced and the platform for the development of many genomics techniques. Therefore, it is not surprising that S. cerevisiae has also been widely...... used in the field of systems biology during the last decade. This thesis investigates S. cerevisiae growth physiology and DNA damage response by using a systems biology approach. Elucidation of the relationship between growth rate and gene expression is important to understand the mechanisms regulating...... set of growth dependent genes by using a multi-factorial experimental design. Moreover, new insights into the metabolic response and transcriptional regulation of these genes have been provided by using systems biology tools (Chapter 3). One of the prerequisite of systems biology should...

  11. L-histidine inhibits biofilm formation and FLO11-associated phenotypes in Saccharomyces cerevisiae flor yeasts.

    Bou Zeidan, Marc; Zara, Giacomo; Viti, Carlo; Decorosi, Francesca; Mannazzu, Ilaria; Budroni, Marilena; Giovannetti, Luciana; Zara, Severino

    2014-01-01

    Flor yeasts of Saccharomyces cerevisiae have an innate diversity of Flo11p which codes for a highly hydrophobic and anionic cell-wall glycoprotein with a fundamental role in biofilm formation. In this study, 380 nitrogen compounds were administered to three S. cerevisiae flor strains handling Flo11p alleles with different expression levels. S. cerevisiae strain S288c was used as the reference strain as it cannot produce Flo11p. The flor strains generally metabolized amino acids and dipeptides as the sole nitrogen source, although with some exceptions regarding L-histidine and histidine containing dipeptides. L-histidine completely inhibited growth and its effect on viability was inversely related to Flo11p expression. Accordingly, L-histidine did not affect the viability of the Δflo11 and S288c strains. Also, L-histidine dramatically decreased air-liquid biofilm formation and adhesion to polystyrene of the flor yeasts with no effect on the transcription level of the Flo11p gene. Moreover, L-histidine modified the chitin and glycans content on the cell-wall of flor yeasts. These findings reveal a novel biological activity of L-histidine in controlling the multicellular behavior of yeasts [corrected].

  12. Fatal Saccharomyces Cerevisiae Aortic Graft Infection

    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.

  13. High level secretion of cellobiohydrolases by Saccharomyces cerevisiae

    Ahlgren Simon

    2011-09-01

    Full Text Available Abstract Background The main technological impediment to widespread utilization of lignocellulose for the production of fuels and chemicals is the lack of low-cost technologies to overcome its recalcitrance. Organisms that hydrolyze lignocellulose and produce a valuable product such as ethanol at a high rate and titer could significantly reduce the costs of biomass conversion technologies, and will allow separate conversion steps to be combined in a consolidated bioprocess (CBP. Development of Saccharomyces cerevisiae for CBP requires the high level secretion of cellulases, particularly cellobiohydrolases. Results We expressed various cellobiohydrolases to identify enzymes that were efficiently secreted by S. cerevisiae. For enhanced cellulose hydrolysis, we engineered bimodular derivatives of a well secreted enzyme that naturally lacks the carbohydrate-binding module, and constructed strains expressing combinations of cbh1 and cbh2 genes. Though there was significant variability in the enzyme levels produced, up to approximately 0.3 g/L CBH1 and approximately 1 g/L CBH2 could be produced in high cell density fermentations. Furthermore, we could show activation of the unfolded protein response as a result of cellobiohydrolase production. Finally, we report fermentation of microcrystalline cellulose (Avicel™ to ethanol by CBH-producing S. cerevisiae strains with the addition of beta-glucosidase. Conclusions Gene or protein specific features and compatibility with the host are important for efficient cellobiohydrolase secretion in yeast. The present work demonstrated that production of both CBH1 and CBH2 could be improved to levels where the barrier to CBH sufficiency in the hydrolysis of cellulose was overcome.

  14. Alleviation of glucose repression of maltose metabolism by MIG1 disruption in Saccharomyces cerevisiae

    Klein, Christopher; Olsson, Lisbeth; Rønnow, B.

    1996-01-01

    The MIG1 gene was disrupted in a haploid laboratory strain (B224) and in an industrial polyploid strain (DGI 342) of Saccharomyces cerevisiae. The alleviation of glucose repression of the expression of MAL genes and alleviation of glucose control of maltose metabolism were investigated in batch...... cultivations on glucose-maltose mixtures. In the MIG1-disrupted haploid strain, glucose repression was partly alleviated; i.e., maltose metabolism was initiated at higher glucose concentrations than in the corresponding wild-type strain. In contrast, the polyploid Delta mig1 strain exhibited an even more...... stringent glucose control of maltose metabolism than the corresponding wild-type strain, which could be explained by a more rigid catabolite inactivation of maltose permease, affecting the uptake of maltose. Growth on the glucose-sucrose mixture showed that the polyploid Delta mig1 strain was relieved...

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

    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.

  16. Improved cider fermentation performance and quality with newly generated Saccharomyces cerevisiae × Saccharomyces eubayanus hybrids.

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

    2017-08-01

    Yeast cryotolerance may be advantageous for cider making, where low temperatures are usually employed. Here, we crossed the cryotolerant S. eubayanus with a S. cerevisiae wine strain and assessed the suitability of the hybrids for low-temperature cider fermentation. All strains fermented the juice to 5% ABV, but at different rates; hybrid strains outperformed S. cerevisiae, which was sensitive to low temperatures. The best hybrid fermented similarly to S. eubayanus. S. eubayanus produced sulphurous off flavours which masked a high concentration of fruity ester notes. This phenotype was absent in the hybrid strains, resulting in distinctly fruitier ciders. Aroma was assessed by an independent consumer panel, which rated the hybrid ciders as identical to the wine strain cider. Both were significantly more pleasant than the S. eubayanus cider. Interspecific hybridization can apparently be used effectively to improve low-temperature fermentation performance without compromising product quality.

  17. Compositions and methods for modeling Saccharomyces cerevisiae metabolism

    2012-01-01

    The invention provides an in silica model for determining a S. cerevisiae physiological function. The model includes a data structure relating a plurality of S. cerevisiae reactants to a plurality of S. cerevisiae reactions, a constraint set for the plurality of S. cerevisiae reactions, and comma...

  18. Ultraviolet-induced reversion of cyc1 alleles in radiation-sensitive strains of yeast. III. rev 3 mutant strains

    Lawrence, C.W.; Crhistensen, R.B.

    1979-01-01

    The role of rev3 gene function in uv-induced mutagenesis in the yeast Saccharomyces cerevisiae has been examined by determining the reversion of 12 well-defined cyc1 mutations in diploid strains homozygous for the rev3-1 or rev3-3 allale. The 12 cyc1 alleles include one ochre, one amber, four initiation, two proline missense, and four frameshift mutations. We find that the rev3 mutations reduce the frequency of UV-induced reversion of all of the cyc1 alleles, though different classes of alleles respond to a different extent. These results imply that the rev3 gene function is required for the production of a wide variety of mutational events, though probably not all, and show that each of the three rev loci have different mutational phenotypes. Such diverse phenotypes are not predicted by the unitary model for bacterial mutagenes, suggesting that this is at best an incomplete description of eukaryotic mutagenesis

  19. Progress in terpene synthesis strategies through engineering of Saccharomyces cerevisiae.

    Paramasivan, Kalaivani; Mutturi, Sarma

    2017-12-01

    (including patents) on this subject to understand the similarities, to identify novel strategies and to contemplate potential possibilities to build a robust yeast cell factory for terpene or terpenoid production. Emphasis is not restricted to metabolic engineering strategies pertaining to sterol and mevalonate pathway, but also other holistic approaches for elsewhere exploitation in the S. cerevisiae genome are discussed. This review also focuses on process considerations and challenges during the mass production of these potential compounds from the engineered strain for commercial exploitation.

  20. PRODUCTION, PROPERTIES AND APPLICATION OF SACCHAROMYCES CEREVISIAE VGSH-2 INULINASE

    G. P. Shuvaeva

    2014-01-01

    Full Text Available Summary. Experimental data on an acid and thermal inactivation of a high refined inulinase (2,1-β-D- fructanfructanohydrolase, KF 3.2.17, produced by the race of Saccharomyces cerevisiae VGSh-2 yeast are presented. The strain of S. cerevisiae VGSh-2 was produced by the method of the induced mutagenesis and deposited to the collection of pure cultures of the chair of biochemistry and biotechnology of Voronezh state university of engineering technologies. The cells of source culture (S. cerevisiae XII were affected step-by-step by the ultra-violet radiation (UFR and UFR in a complex with a chemical mutagen (etilenimine. The culture was grown up by the method of liquid-phase deep cultivation on a constant nutrient medium. Refining conditions for inulinase are sorted out. Activity of enzyme dependence on physical and chemical factors (рН and temperature is obtained and numerical values of the main kinetic constants – Km and Vmax are determined. The structure of enzyme molecule is studied by an infrared-spectroscopy method: the type and relative quantity of elements of secondary structure of protein are defined. Substrate binding groups of the active center of an inulinase are found. The comparative analysis of the ability to hydrolysis of inulin in several enzyme preparations from Jerusalem artichoke and to the subsequent their fermentation by the VGSh-2 and XI S. cerevisiae yeasts is carried out. Optimum conditions of enzyme hydrolysis of inulin are selected. Research of the fermentation process of starchcontaining raw materials by yeasts of VGSh-2 and XI races is done. It is established that the using of VGSh-2 S. cerevisiae yeast for a grain wort and the Jerusalem artichoke fermentation, allows to increase an extraction of ethyl alcohol comparing to control race, to improve its quality characteristics, and also allows to predict the using of new race in the food industry for production ethanol from grain raw materials and a fermentation of

  1. Bulk segregant analysis by high-throughput sequencing reveals a novel xylose utilization gene from Saccharomyces cerevisiae.

    Jared W Wenger

    2010-05-01

    Full Text Available Fermentation of xylose is a fundamental requirement for the efficient production of ethanol from lignocellulosic biomass sources. Although they aggressively ferment hexoses, it has long been thought that native Saccharomyces cerevisiae strains cannot grow fermentatively or non-fermentatively on xylose. Population surveys have uncovered a few naturally occurring strains that are weakly xylose-positive, and some S. cerevisiae have been genetically engineered to ferment xylose, but no strain, either natural or engineered, has yet been reported to ferment xylose as efficiently as glucose. Here, we used a medium-throughput screen to identify Saccharomyces strains that can increase in optical density when xylose is presented as the sole carbon source. We identified 38 strains that have this xylose utilization phenotype, including strains of S. cerevisiae, other sensu stricto members, and hybrids between them. All the S. cerevisiae xylose-utilizing strains we identified are wine yeasts, and for those that could produce meiotic progeny, the xylose phenotype segregates as a single gene trait. We mapped this gene by Bulk Segregant Analysis (BSA using tiling microarrays and high-throughput sequencing. The gene is a putative xylitol dehydrogenase, which we name XDH1, and is located in the subtelomeric region of the right end of chromosome XV in a region not present in the S288c reference genome. We further characterized the xylose phenotype by performing gene expression microarrays and by genetically dissecting the endogenous Saccharomyces xylose pathway. We have demonstrated that natural S. cerevisiae yeasts are capable of utilizing xylose as the sole carbon source, characterized the genetic basis for this trait as well as the endogenous xylose utilization pathway, and demonstrated the feasibility of BSA using high-throughput sequencing.

  2. Cellular responses of Saccharomyces cerevisiae to DNA damage

    Ciesla, Z.; Sledziewska-Gojska, E.; Nowicka, A.; Mieczkowski, P.; Fikus, M.U.; Koprowski, P.

    1998-01-01

    Full text. Several experimental strategies have been used to study responses of S. cerevisiae cells to DNA damage. One approach was based on the isolation of novel genes, the expression of which is induced by lesions in DNA. One of these genes, DIN7, was cloned and partially characterized previously. The product of DIN7 belongs to a large family of proteins involved in DNA repair and mutagenesis. This family includes Rad2, Rad27 and ExoI proteins of S. cerevisiae and their respective human homologues, all of which are endowed with DNA nuclease activity. To study cellular function of Din7 we constructed the pPK3 plasmid carrying DIN7 fused to the GAL1 promoter. Effects of DIN7 overproduction on the phenotypes of wild-type cells and of rad27 and exoI mutants were examined. Overproduction of Din7 does not seem to affect the proficiency of wild-type S. cerevisiae cells in recombination and mutagenesis. Also, overexpression of DIN7 does not suppress the deficiency of the EXOI gene product, the closest homologue of Din7, both in recombination and in controlling the fidelity of DNA replication. Unexpectedly, we found that elevated levels of Din7 result in a very high frequency of mitochondrial rho - mutants. A high frequency of production of rho - mutants wa s also observed in strains defective in the functioning of the Dun1 protein kinase involved in signal transmission in cells exposed to DNA damaging agents. Interestingly, deficiency of Dun1 results also in a significant derepression of the DIN7 gene. Experiments are under way to distinguish whether a high cellular level of Din7 specifically decreases stability of mitochondrial DNA or affects stability of chromosomal DNA as well. Analysis of previously constructed S. cerevisiae strains carrying random geno mic fusions with reporter lacZ gene, allowed us to identify the reading frame YBR173c, on chromosome II as a novel damage inducible gene - DIN8. We have shown that DIN8-lacZ fusion is induced in yeast cells treated

  3. Fermentation of Apple Juice with a Selected Yeast Strain Isolated from the Fermented Foods of Himalayan Regions and Its Organoleptic Properties

    Kanwar, S. S.; Keshani,

    2016-01-01

    Twenty-three Saccharomyces cerevisiae strains isolated from different fermented foods of Western Himalayas have been studied for strain level and functional diversity in our department. Among these 23 strains, 10 S. cerevisiae strains on the basis of variation in their brewing traits were selected to study their organoleptic effect at gene level by targeting ATF1 gene, which is responsible for ester synthesis during fermentation. Significant variation was observed in ATF1 gene sequences, sugg...

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

    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.

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

    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.

  6. The expression of glycerol facilitators from various yeast species improves growth on glycerol of Saccharomyces cerevisiae

    Mathias Klein

    2016-12-01

    Full Text Available Glycerol is an abundant by-product during biodiesel production and additionally has several assets compared to sugars when used as a carbon source for growing microorganisms in the context of biotechnological applications. However, most strains of the platform production organism Saccharomyces cerevisiae grow poorly in synthetic glycerol medium. It has been hypothesized that the uptake of glycerol could be a major bottleneck for the utilization of glycerol in S. cerevisiae. This species exclusively relies on an active transport system for glycerol uptake. This work demonstrates that the expression of predicted glycerol facilitators (Fps1 homologues from superior glycerol-utilizing yeast species such as Pachysolen tannophilus, Komagataella pastoris, Yarrowia lipolytica and Cyberlindnera jadinii significantly improves the growth performance on glycerol of the previously selected glycerol-consuming S. cerevisiae wild-type strain (CBS 6412-13A. The maximum specific growth rate increased from 0.13 up to 0.18 h−1 and a biomass yield coefficient of 0.56 gDW/gglycerol was observed. These results pave the way for exploiting the assets of glycerol in the production of fuels, chemicals and pharmaceuticals based on baker's yeast. Keywords: Yeast, Saccharomyces cerevisiae, Glycerol, Transport, Glycerol facilitator, Fps1, Stl1

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

    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.

  8. Multiplex metabolic pathway engineering using CRISPR/Cas9 in Saccharomyces cerevisiae

    Jakociunas, Tadas; Bonde, Ida; Herrgard, Markus

    2015-01-01

    CRISPR/Cas9 is a simple and efficient tool for targeted and marker-free genome engineering. Here, we report the development and successful application of a multiplex CRISPR/Cas9 system for genome engineering of up to 5 different genomic loci in one transformation step in baker's yeast Saccharomyces...... cerevisiae. To assess the specificity of the tool we employed genome re-sequencing to screen for off-target sites in all single knock-out strains targeted by different gRNAs. This extensive analysis identified no more genome variants in CRISPR/Cas9 engineered strains compared to wild-type reference strains...

  9. Bacterial xylose isomerases from the mammal gut Bacteroidetes cluster function in Saccharomyces cerevisiae for effective xylose fermentation.

    Peng, Bingyin; Huang, Shuangcheng; Liu, Tingting; Geng, Anli

    2015-05-17

    Xylose isomerase (XI) catalyzes the conversion of xylose to xylulose, which is the key step for anaerobic ethanolic fermentation of xylose. Very few bacterial XIs can function actively in Saccharomyces cerevisiae. Here, we illustrate a group of XIs that would function for xylose fermentation in S. cerevisiae through phylogenetic analysis, recombinant yeast strain construction, and xylose fermentation. Phylogenetic analysis of deposited XI sequences showed that XI evolutionary relationship was highly consistent with the bacterial taxonomic orders and quite a few functional XIs in S. cerevisiae were clustered with XIs from mammal gut Bacteroidetes group. An XI from Bacteroides valgutus in this cluster was actively expressed in S. cerevisiae with an activity comparable to the fungal XI from Piromyces sp. Two XI genes were isolated from the environmental metagenome and they were clustered with XIs from environmental Bacteroidetes group. These two XIs could not be expressed in yeast with activity. With the XI from B. valgutus expressed in S. cerevisiae, background yeast strains were optimized by pentose metabolizing pathway enhancement and adaptive evolution in xylose medium. Afterwards, more XIs from the mammal gut Bacteroidetes group, including those from B. vulgatus, Tannerella sp. 6_1_58FAA_CT1, Paraprevotella xylaniphila and Alistipes sp. HGB5, were individually transformed into S. cerevisiae. The known functional XI from Orpinomyces sp. ukk1, a mammal gut fungus, was used as the control. All the resulting recombinant yeast strains were able to ferment xylose. The respiration-deficient strains harboring B. vulgatus and Alistipes sp. HGB5 XI genes respectively obtained specific xylose consumption rate of 0.662 and 0.704 g xylose gcdw(-1) h(-1), and ethanol specific productivity of 0.277 and 0.283 g ethanol gcdw(-1) h(-1), much comparable to those obtained by the control strain carrying Orpinomyces sp. ukk1 XI gene. This study demonstrated that XIs clustered in the

  10. Selection of inoculum size and Saccharomyces cerevisiae strain for ...

    SAM

    2014-07-02

    Jul 2, 2014 ... The aim of this work was to select an inoculum concentration and a ... (UFPEDA 1238 and UFPEDA 1334) were used to ferment a culture medium containing .... quantified by HPLC (Agilent HP 1100, Germany) in an Aminex.

  11. Increased ethanol production by deletion of HAP4 in recombinant xylose-assimilating Saccharomyces cerevisiae.

    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.

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

    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.

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

    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.

  14. Ultraviolet-endonuclease activity in cell extracts of Saccharomyces cerevisiae mutants defective in excision of pyrimidine dimers

    Bekker, M.L.; Kaboev, O.K.; Akhmedov, A.T.; Luchkina, L.A.

    1980-01-01

    Cell-free extracts of ultraviolet-sensitive mutants of Saccharomyces cerevisiae defective in excision of pyrimidine dimers, rad1, rad2, rad3, rad4, rad10, and rad16, as well as the extracts of the wild-type strain RAD+, display ultraviolet-endonuclease activity

  15. ISOLATION OF THE CANDIDA TROPICALIS GENE FOR P450 LANOSTEROL DEMETHYLASE AND ITS EXPRESSION IN SACCAROMYCES CEREVISIAE

    We have isolated the gene for cytochrome P450 lanosterol 14-demethylase (14DM) from the yeast Candida tropicalis. This was accomplished by screening genomic libraries of strain ATCC750 in E. coli using a DNA fragment containing the yeast Saccharomyces cerevisiae 14DM gene. Identi...

  16. Impact of overexpressing NADH kinase on glucose and xylose metabolism in recombinant xylose-utilizing Saccharomyces cerevisiae

    Hou, Jin; Vemuri, G. N.; Bao, X. M.

    2009-01-01

    of overexpressing the native NADH kinase (encoded by the POS5 gene) in xylose-consuming recombinant S. cerevisiae directed either into the cytosol or to the mitochondria was evaluated. The physiology of the NADH kinase containing strains was also evaluated during growth on glucose. Overexpressing NADH kinase...

  17. Rapid and efficient galactose fermentation by engineered Saccharomyces cerevisiae.

    Quarterman, Josh; Skerker, Jeffrey M; Feng, Xueyang; Liu, Ian Y; Zhao, Huimin; Arkin, Adam P; Jin, Yong-Su

    2016-07-10

    In the important industrial yeast Saccharomyces cerevisiae, galactose metabolism requires energy production by respiration; therefore, this yeast cannot metabolize galactose under strict anaerobic conditions. While the respiratory dependence of galactose metabolism provides benefits in terms of cell growth and population stability, it is not advantageous for producing fuels and chemicals since a substantial fraction of consumed galactose is converted to carbon dioxide. In order to force S. cerevisiae to use galactose without respiration, a subunit (COX9) of a respiratory enzyme was deleted, but the resulting deletion mutant (Δcox9) was impaired in terms of galactose assimilation. Interestingly, after serial sub-cultures on galactose, the mutant evolved rapidly and was able to use galactose via fermentation only. The evolved strain (JQ-G1) produced ethanol from galactose with a 94% increase in yield and 6.9-fold improvement in specific productivity as compared to the wild-type strain. (13)C-metabolic flux analysis demonstrated a three-fold reduction in carbon flux through the TCA cycle of the evolved mutant with redirection of flux toward the fermentation pathway. Genome sequencing of the JQ-G1 strain revealed a loss of function mutation in a master negative regulator of the Leloir pathway (Gal80p). The mutation (Glu348*) in Gal80p was found to act synergistically with deletion of COX9 for efficient galactose fermentation, and thus the double deletion mutant Δcox9Δgal80 produced ethanol 2.4 times faster and with 35% higher yield than a single knockout mutant with deletion of GAL80 alone. When we introduced a functional COX9 cassette back into the JQ-G1 strain, the JQ-G1-COX9 strain showed a 33% reduction in specific galactose uptake rate and a 49% reduction in specific ethanol production rate as compared to JQ-G1. The wild-type strain was also subjected to serial sub-cultures on galactose but we failed to isolate a mutant capable of utilizing galactose without

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

    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.

  19. Biocatalytic production of adipic acid from glucose using engineered Saccharomyces cerevisiae

    Kaushik Raj

    2018-06-01

    Full Text Available Adipic acid is an important industrial chemical used in the synthesis of nylon-6,6. The commercial synthesis of adipic acid uses petroleum-derived benzene and releases significant quantities of greenhouse gases. Biocatalytic production of adipic acid from renewable feedstocks could potentially reduce the environmental damage and eliminate the need for fossil fuel precursors. Recently, we have demonstrated the first enzymatic hydrogenation of muconic acid to adipic acid using microbial enoate reductases (ERs - complex iron-sulfur and flavin containing enzymes. In this work, we successfully expressed the Bacillus coagulans ER in a Saccharomyces cerevisiae strain producing muconic acid and developed a three-stage fermentation process enabling the synthesis of adipic acid from glucose. The ability to express active ERs and significant acid tolerance of S. cerevisiae highlight the applicability of the developed yeast strain for the biocatalytic production of adipic acid from renewable feedstocks. Keywords: Biosynthesis, Renewable resources, Yeast, Adipic acid, Synthetic biology

  20. Cell surface engineering of Saccharomyces cerevisiae combined with membrane separation technology for xylitol production from rice straw hydrolysate.

    Guirimand, Gregory; Sasaki, Kengo; Inokuma, Kentaro; Bamba, Takahiro; Hasunuma, Tomohisa; Kondo, Akihiko

    2016-04-01

    Xylitol, a value-added polyol deriving from D-xylose, is widely used in both the food and pharmaceutical industries. Despite extensive studies aiming to streamline the production of xylitol, the manufacturing cost of this product remains high while demand is constantly growing worldwide. Biotechnological production of xylitol from lignocellulosic waste may constitute an advantageous and sustainable option to address this issue. However, to date, there have been few reports of biomass conversion to xylitol. In the present study, xylitol was directly produced from rice straw hydrolysate using a recombinant Saccharomyces cerevisiae YPH499 strain expressing cytosolic xylose reductase (XR), along with β-glucosidase (BGL), xylosidase (XYL), and xylanase (XYN) enzymes (co-)displayed on the cell surface; xylitol production by this strain did not require addition of any commercial enzymes. All of these enzymes contributed to the consolidated bioprocessing (CBP) of the lignocellulosic hydrolysate to xylitol to produce 5.8 g/L xylitol with 79.5 % of theoretical yield from xylose contained in the biomass. Furthermore, nanofiltration of the rice straw hydrolysate provided removal of fermentation inhibitors while simultaneously increasing sugar concentrations, facilitating high concentration xylitol production (37.9 g/L) in the CBP. This study is the first report (to our knowledge) of the combination of cell surface engineering approach and membrane separation technology for xylitol production, which could be extended to further industrial applications.

  1. Phylogenetic relationship and Fourier-transform infrared spectroscopy-derived lipid determinants of lifespan parameters in the Saccharomyces cerevisiae yeast.

    Molon, Mateusz; Zebrowski, Jacek

    2017-06-01

    Yeast ageing has been gaining much attention in gerontology research, yet the process itself is still not entirely clear. One of the constraints related to the use of the Saccharomyces cerevisiae yeast in studies is the ambiguity of the results concerning ageing determinants for different genetic backgrounds. In this paper, we compare reproductive potentials and lifespans of seven widely used haploid laboratory strains differing in daughter cells production capabilities and highlight the importance of choosing an appropriate genotype for the studies on ageing. Moreover, we show here links between post-reproductive lifespan and lipid metabolism, as well as between reproductive potential, reproductive lifespan and phylogenetic relationship. Using FTIR spectroscopy that generated a biochemical fingerprint of cells, coupled with chemometrics, we found that the band of carbonyl (C = O) stretching vibration discriminates the strains according to post-reproductive lifespan. The results indicated that prolonged post-reproductive lifespan was associated with relatively lower amount of fatty acids esterified to phospholipids compared to a free acid pool, thus implying phospholipid metabolism for the post-reproductive lifespan of yeast. In addition, phylogenetic analysis showed a correlation between nucleotide similarity and the reproductive potential or reproductive lifespan, but not to the longevity expressed in time units. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. Acetylation dynamics and stoichiometry in Saccharomyces cerevisiae

    Weinert, Brian Tate; Iesmantavicius, Vytautas; Moustafa, Tarek

    2014-01-01

    Lysine acetylation is a frequently occurring posttranslational modification; however, little is known about the origin and regulation of most sites. Here we used quantitative mass spectrometry to analyze acetylation dynamics and stoichiometry in Saccharomyces cerevisiae. We found that acetylation...

  3. Isolation of glutathione-deficient mutants of the yeast Saccharomyces cerevisiae

    Kistler, M.; Eckardt, F.; Summer, K.-H.

    1986-01-01

    Glutathione-deficient (gsh - ) mutants of the yeast Saccharomyces cerevisiae were isolated after UV treatment using MNNG as selective agent. For genetic and biochemical characterization 5 mutant strains were chosen which exhibited considerably decreased residual GSH contents varying from 2 to 6% of the wild-type levels. All 5 isolates showed a 2:2 segregation of the gsh - :GSH + phenotypes alluding to a monogenic recessive mutation. Complementation analysis indicates that all gsh - mutants belong to one complementation group. (Auth.)

  4. The yeast Saccharomyces cerevisiae DNA polymerase IV: possible involvement in double strand break DNA repair.

    Leem, S H; Ropp, P A; Sugino, A

    1994-01-01

    We identified and purified a new DNA polymerase (DNA polymerase IV), which is similar to mammalian DNA polymerase beta, from Saccharomyces cerevisiae and suggested that it is encoded by YCR14C (POLX) on chromosome III. Here, we provided a direct evidence that the purified DNA polymerase IV is indeed encoded by POLX. Strains harboring a pol4 deletion mutation exhibit neither mitotic growth defect nor a meiosis defect, suggesting that DNA polymerase IV participates in nonessential functions in ...

  5. Effect of aeration on the fermentative activity of Saccharomyces cerevisiae cultured in apple juice

    Estela-Escalante, W.; Rychtera, M.; Melzoch, K.; Hatta-Sakoda, B.

    2012-01-01

    The influence of aeration on the fermentative activity of Saccharomyces cerevisiaeRTVE V 15-1-416 was studied in order to evaluate the synthesis of fermentation by-products. To achieve this, the strain was cultured in Erlenmeyer flasks and bioreactor containing sterilized and aroma removed apple juice. The chemical compounds produced during fermentations in shaken (200 min-¹) and static (without agitation) flasks and bioreactor, all in batch mode, were determined by GC and HPLC. The results s...

  6. Phenotypic and metabolic traits of commercial Saccharomyces cerevisiae yeasts.

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

    2014-01-01

    Currently, pursuing yeast strains that display both a high potential fitness for alcoholic fermentation and a favorable impact on quality is a major goal in the alcoholic beverage industry. This considerable industrial interest has led to many studies characterizing the phenotypic and metabolic traits of commercial yeast populations. In this study, 20 Saccharomyces cerevisiae strains from different geographical origins exhibited high phenotypic diversity when their response to nine biotechnologically relevant conditions was examined. Next, the fermentation fitness and metabolic traits of eight selected strains with a unique phenotypic profile were evaluated in a high-sugar synthetic medium under two nitrogen regimes. Although the strains exhibited significant differences in nitrogen requirements and utilization rates, a direct relationship between nitrogen consumption, specific growth rate, cell biomass, cell viability, acetic acid and glycerol formation was only observed under high-nitrogen conditions. In contrast, the strains produced more succinic acid under the low-nitrogen regime, and a direct relationship with the final cell biomass was established. Glucose and fructose utilization patterns depended on both yeast strain and nitrogen availability. For low-nitrogen fermentation, three strains did not fully degrade the fructose. This study validates phenotypic and metabolic diversity among commercial wine yeasts and contributes new findings on the relationship between nitrogen availability, yeast cell growth and sugar utilization. We suggest that measuring nitrogen during the stationary growth phase is important because yeast cells fermentative activity is not exclusively related to population size, as previously assumed, but it is also related to the quantity of nitrogen consumed during this growth phase.

  7. Assay for adhesion and agar invasion in S. cerevisiae.

    Guldal, Cemile G; Broach, James

    2006-11-08

    Yeasts are found in natural biofilms, where many microorganisms colonize surfaces. In artificial environments, such as surfaces of man-made objects, biofilms can reduce industrial productivity, destroy structures, and threaten human life. 1-3 On the other hand, harnessing the power of biofilms can help clean the environment and generate sustainable energy. 4-8 The ability of S. cerevisiae to colonize surfaces and participate in complex biofilms was mostly ignored until the rediscovery of the differentiation programs triggered by various signaling pathways and environmental cues in this organism. 9, 10 The continuing interest in using S. cerevisiae as a model organism to understand the interaction and convergence of signaling pathways, such as the Ras-PKA, Kss1 MAPK, and Hog1 osmolarity pathways, quickly placed S. cerevisiae in the junction of biofilm biology and signal transduction research. 11-20 To this end, differentiation of yeast cells into long, adhesive, pseudohyphal filaments became a convenient readout for the activation of signal transduction pathways upon various environmental changes. However, filamentation is a complex collection of phenotypes, which makes assaying for it as if it were a simple phenotype misleading. In the past decade, several assays were successfully adopted from bacterial biofilm studies to yeast research, such as MAT formation assays to measure colony spread on soft agar and crystal violet staining to quantitatively measure cell-surface adherence. 12, 21 However, there has been some confusion in assays developed to qualitatively assess the adhesive and invasive phenotypes of yeast in agar. Here, we present a simple and reliable method for assessing the adhesive and invasive quality of yeast strains with easy-to-understand steps to isolate the adhesion assessment from invasion assessment. Our method, adopted from previous studies, 10, 16 involves growing cells in liquid media and plating on differential nutrient conditions for growth

  8. The evolution of gene expression QTL in Saccharomyces cerevisiae.

    James Ronald

    2007-08-01

    Full Text Available Understanding the evolutionary forces that influence patterns of gene expression variation will provide insights into the mechanisms of evolutionary change and the molecular basis of phenotypic diversity. To date, studies of gene expression evolution have primarily been made by analyzing how gene expression levels vary within and between species. However, the fundamental unit of heritable variation in transcript abundance is the underlying regulatory allele, and as a result it is necessary to understand gene expression evolution at the level of DNA sequence variation. Here we describe the evolutionary forces shaping patterns of genetic variation for 1206 cis-regulatory QTL identified in a cross between two divergent strains of Saccharomyces cerevisiae. We demonstrate that purifying selection against mildly deleterious alleles is the dominant force governing cis-regulatory evolution in S. cerevisiae and estimate the strength of selection. We also find that essential genes and genes with larger codon bias are subject to slightly stronger cis-regulatory constraint and that positive selection has played a role in the evolution of major trans-acting QTL.

  9. Comparative proteomics analysis of engineered Saccharomyces cerevisiae with enhanced biofuel precursor production.

    Xiaoling Tang

    Full Text Available The yeast Saccharomyces cerevisiae was metabolically modified for enhanced biofuel precursor production by knocking out genes encoding mitochondrial isocitrate dehydrogenase and over-expression of a heterologous ATP-citrate lyase. A comparative iTRAQ-coupled 2D LC-MS/MS analysis was performed to obtain a global overview of ubiquitous protein expression changes in S. cerevisiae engineered strains. More than 300 proteins were identified. Among these proteins, 37 were found differentially expressed in engineered strains and they were classified into specific categories based on their enzyme functions. Most of the proteins involved in glycolytic and pyruvate branch-point pathways were found to be up-regulated and the proteins involved in respiration and glyoxylate pathway were however found to be down-regulated in engineered strains. Moreover, the metabolic modification of S. cerevisiae cells resulted in a number of up-regulated proteins involved in stress response and differentially expressed proteins involved in amino acid metabolism and protein biosynthesis pathways. These LC-MS/MS based proteomics analysis results not only offered extensive information in identifying potential protein-protein interactions, signal pathways and ubiquitous cellular changes elicited by the engineered pathways, but also provided a meaningful biological information platform serving further modification of yeast cells for enhanced biofuel production.

  10. Improving Saccharomyces cerevisiae ethanol production and tolerance via RNA polymerase II subunit Rpb7.

    Qiu, Zilong; Jiang, Rongrong

    2017-01-01

    Classical strain engineering methods often have limitations in altering multigenetic cellular phenotypes. Here we try to improve Saccharomyces cerevisiae ethanol tolerance and productivity by reprogramming its transcription profile through rewiring its key transcription component RNA polymerase II (RNAP II), which plays a central role in synthesizing mRNAs. This is the first report on using directed evolution method to engineer RNAP II to alter S. cerevisiae strain phenotypes. Error-prone PCR was employed to engineer the subunit Rpb7 of RNAP II to improve yeast ethanol tolerance and production. Based on previous studies and the presumption that improved ethanol resistance would lead to enhanced ethanol production, we first isolated variant M1 with much improved resistance towards 8 and 10% ethanol. The ethanol titers of M1 was ~122 g/L (96.58% of the theoretical yield) under laboratory very high gravity (VHG) fermentation, 40% increase as compared to the control. DNA microarray assay showed that 369 genes had differential expression in M1 after 12 h VHG fermentation, which are involved in glycolysis, alcoholic fermentation, oxidative stress response, etc. This is the first study to demonstrate the possibility of engineering eukaryotic RNAP to alter global transcription profile and improve strain phenotypes. Targeting subunit Rpb7 of RNAP II was able to bring differential expression in hundreds of genes in S. cerevisiae , which finally led to improvement in yeast ethanol tolerance and production.

  11. A novel approach for the improvement of ethanol fermentation by Saccharomyces cerevisiae

    Hou, L.; Cao, X.; Wang, C. [Tianjin Univ. of Science and Technology, Tianjin (China). Key Laboratory of Food Nutrition and Safety

    2010-06-15

    The partial substitution of fossil fuels with bioethanol has become an important strategy for the use of renewable energy. Ethanol production is generally achieved through fermentation of starch or sugar-based feedstock by Saccharomyces cerevisiae. In order to meet the growing demand for ethanol, there is a need for new yeast strains that can produce ethanol more efficiently and cost effectively. This paper presented a new genome engineering approach that was developed to improve ethanol production by S. cerevisiae. In this study, the aneuploid strain constructed on the base of tetraploid cells was shown to have favourable metabolic traits in very high gravity (VHG) fermentation with 300 g/L glucose as the carbon source. The tetraploid strain was constructed using the plasmid YCplac33-GHK, which comprised the HO gene encoding the site-specific HO endonucleases. The aneuploid strain, WT4-M, was chosen and screened once the tetraploid cells were treated with methyl benzimidazole-2-yl-carbamate to induce loss of mitotic chromosomes. The aneuploid strain WT4-M increased ethanol production as well as osmotic and thermal tolerance. The sugar to ethanol conversion rate also improved. It was concluded that this new approach is valuable for creating yeast strains with better fermentation characteristics. 25 refs., 3 figs.

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

    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.

  13. Evaluation of Ethanol Production Activity by Engineered Saccharomyces cerevisiae Fermenting Cellobiose through the Phosphorolytic Pathway in Simultaneous Saccharification and Fermentation of Cellulose.

    Lee, Won-Heong; Jin, Yong-Su

    2017-09-28

    In simultaneous saccharification and fermentation (SSF) for production of cellulosic biofuels, engineered Saccharomyces cerevisiae capable of fermenting cellobiose has provided several benefits, such as lower enzyme costs and faster fermentation rate compared with wild-type S. cerevisiae fermenting glucose. In this study, the effects of an alternative intracellular cellobiose utilization pathway-a phosphorolytic pathway based on a mutant cellodextrin transporter (CDT-1 (F213L)) and cellobiose phosphorylase (SdCBP)-was investigated by comparing with a hydrolytic pathway based on the same transporter and an intracellular β-glucosidase (GH1-1) for their SSF performances under various conditions. Whereas the phosphorolytic and hydrolytic cellobiose-fermenting S. cerevisiae strains performed similarly under the anoxic SSF conditions, the hydrolytic S. cerevisiae performed slightly better than the phosphorolytic S. cerevisiae under the microaerobic SSF conditions. Nonetheless, the phosphorolytic S. cerevisiae expressing the mutant CDT-1 showed better ethanol production than the glucose-fermenting S. cerevisiae with an extracellular β-glucosidase, regardless of SSF conditions. These results clearly prove that introduction of the intracellular cellobiose metabolic pathway into yeast can be effective on cellulosic ethanol production in SSF. They also demonstrate that enhancement of cellobiose transport activity in engineered yeast is the most important factor affecting the efficiency of SSF of cellulose.

  14. The fermentative activity and morphological specialitys of yeast Saccharomyces cerevisiae Y-503 at cultivation in aerobic and anaerobic conditions

    S. Ts. Kotenko

    2010-01-01

    Full Text Available The influence of aerobic and anaerobic conditions of cultivation on structure of cells and enzymes` activity of yeast S. cerevisiae Y-503 is researched. The results of experiment have shown that nutrient medium containing geothermal water in aerobic conditions of cultivation improves biotechnological properties of yeast important for manufacturing bread, and anaerobic activates the enzymes participating in synthesis of ethanol. Strain S. cerevisiae Y-503 can successfully be used both in baking, and in the spirit industries

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

    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.

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

    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.

  17. H. guilliermondii impacts growth kinetics and metabolic activity of S. cerevisiae: the role of initial nitrogen concentration.

    Lage, Patrícia; Barbosa, Catarina; Mateus, Beatriz; Vasconcelos, Isabel; Mendes-Faia, Arlete; Mendes-Ferreira, Ana

    2014-02-17

    Non-Saccharomyces yeasts include different species which comprise an ecologically and biochemically diverse group capable of altering fermentation dynamics and wine composition and flavour. In this study, single- and mixed-culture of Hanseniaspora guilliermondii and Saccharomyces cerevisiae were used to ferment natural grape-juice, under two nitrogen regimes. In single-culture the strain H. guilliermondii failed to complete total sugar breakdown even though the nitrogen available has not been a limiting factor of its growth or fermentative activity. In mixed-culture, that strain negatively interfered with the growth and fermentative performance of S. cerevisiae, resulting in lower fermentation rate and longer fermentation length, irrespective of the initial nitrogen concentration. The impact of co-inoculation on the volatile compounds profile was more evident in the wines obtained from DAP-supplemented musts, characterised by increased levels of ethyl and acetate esters, associated with fruity and floral character of wines. Moreover, the levels of fatty acids and sulphur compounds which are responsible for unpleasant odours that depreciate wine sensory quality were significantly lower. Accordingly, data obtained suggests that the strain H. guilliermondii has potential to be used as adjunct of S. cerevisiae in wine industry, although possible interactions with S. cerevisiae still need to be elucidated. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Radioimmunoassay for yeast killer toxin from Saccharomyces cerevisiae

    Siddiqui, F.A.; Bussey, H.

    1981-01-01

    A radioimmunoassay was developed for the K1 killer toxin from strain T158C/S14a of Saccharomyces cerevisiae. Iodine 125-labelled toxin was made to a specific activity of 100 μCi/mg of protein. Antibody to purified toxin was prepared in rabbits using toxin cross-linked to itself. These antibodies, partially purified by 50 percent ammonium sulfate precipitation and Sepharose CL-6B column chromatography, produced one precipitation band with killer toxin and bound 125 I-labelled toxin in a radioimmunoassay. The antibody preparation also bound with the toxins from another K1 killer, A364A, and three chromosomal superkiller mutants derived from it. (auth)

  19. Higher-order structure of Saccharomyces cerevisiae chromatin

    Lowary, P.T.; Widom, J.

    1989-01-01

    We have developed a method for partially purifying chromatin from Saccharomyces cerevisiae (baker's yeast) to a level suitable for studies of its higher-order folding. This has required the use of yeast strains that are free of the ubiquitous yeast killer virus. Results from dynamic light scattering, electron microscopy, and x-ray diffraction show that the yeast chromatin undergoes a cation-dependent folding into 30-nm filaments that resemble those characteristic of higher-cell chromatin; moreover, the packing of nucleosomes within the yeast 30-nm filaments is similar to that of higher cells. These results imply that yeast has a protein or protein domain that serves the role of the histone H 1 found in higher cells; physical and genetic studies of the yeast activity could help elucidate the structure and function of H 1. Images of the yeast 30-nm filaments can be used to test crossed-linker models for 30-nm filament structure

  20. Characteristics of Saccharomyces cerevisiae yeasts exhibiting rough colonies and pseudohyphal morphology with respect to alcoholic fermentation.

    Reis, Vanda Renata; Bassi, Ana Paula Guarnieri; da Silva, Jessica Carolina Gomes; Ceccato-Antonini, Sandra Regina

    2013-12-01

    Among the native yeasts found in alcoholic fermentation, rough colonies associated with pseudohyphal morphology belonging to the species Saccharomyces cerevisiae are very common and undesirable during the process. The aim of this work was to perform morphological and physiological characterisations of S. cerevisiae strains that exhibited rough and smooth colonies in an attempt to identify alternatives that could contribute to the management of rough colony yeasts in alcoholic fermentation. Characterisation tests for invasiveness in Agar medium, killer activity, flocculation and fermentative capacity were performed on 22 strains (11 rough and 11 smooth colonies). The effects of acid treatment at different pH values on the growth of two strains ("52"--rough and "PE-02"--smooth) as well as batch fermentation tests with cell recycling and acid treatment of the cells were also evaluated. Invasiveness in YPD Agar medium occurred at low frequency; ten of eleven rough yeasts exhibited flocculation; none of the strains showed killer activity; and the rough strains presented lower and slower fermentative capacities compared to the smooth strains in a 48-h cycle in a batch system with sugar cane juice. The growth of the rough strain was severely affected by the acid treatment at pH values of 1.0 and 1.5; however, the growth of the smooth strain was not affected. The fermentative efficiency in mixed fermentation (smooth and rough strains in the same cell mass proportion) did not differ from the efficiency obtained with the smooth strain alone, most likely because the acid treatment was conducted at pH 1.5 in a batch cell-recycle test. A fermentative efficiency as low as 60% was observed with the rough colony alone.

  1. Overexpression of smORF YNR034W-A/EGO4 in Saccharomyces cerevisiae increases the fermentative efficiency of Agave tequilana Weber must.

    Vargas-Maya, Naurú Idalia; González-Hernández, Gloria Angélica; Padilla-Guerrero, Israel Enrique; Torres-Guzmán, Juan Carlos

    2017-01-01

    Fermentative processes are widely used to produce food, beverages and biofuels. Saccharomyces cerevisiae is an efficient ethanol-producing microorganism. However, a concentration of high ethanol and other metabolites can affect yeast viability and decrease the ethanol yield. Many studies have focused on improving the fermentative efficiency, mostly through the genetic engineering of genes that have a direct impact on specific metabolic pathways. In the present study, we characterized a small open reading frame encoding a protein with an unknown function and biological role termed YNR034W-A. We analyzed the expression profile of the YNR034W-A gene during growth and glucose treatment, finding that it is expressed during the diauxic shift and stationary phase and is negatively regulated by glucose. We overexpressed the YNR034W-A gene in the BY4741 laboratory strain and a wild-type yeast strain (AR5) isolated during the Tequila fermentation process. Transformant derivatives of the AR5 strain showed an improved fermentative efficiency during fermentation of Agave tequilana Weber juice. We suggest that the improved fermentative efficiency is the result of a higher stress tolerance response in the YNR034W-A overexpressing transformant.

  2. Overexpression of the truncated version of ILV2 enhances glycerol production in Saccharomyces cerevisiae.

    Murashchenko, Lidiia; Abbas, Charles; Dmytruk, Kostyantyn; Sibirny, Andriy

    2016-08-01

    Acetolactate synthase is a mitochondrial enzyme that catalyses the conversion of two pyruvate molecules to an acetolactate molecule with release of carbon dioxide. The overexpression of the truncated version of the corresponding gene, ILV2, that codes for presumably cytosolic acetolactate synthase in the yeast Saccharomyces cerevisiae, led to a decrease in intracellular pyruvate concentration. This recombinant strain was also characterized by a four-fold increase in glycerol production, with a concomitant 1.8-fold reduction in ethanol production, when compared to that of the wild-type strain under anaerobic conditions in a glucose alcoholic fermentation. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  3. Engineered CRISPR/Cas9 system for multiplex genome engineering of polyploid industrial yeast strains.

    Lian, Jiazhang; Bao, Zehua; Hu, Sumeng; Zhao, Huimin

    2018-06-01

    The CRISPR/Cas9 system has been widely used for multiplex genome engineering of Saccharomyces cerevisiae. However, its application in manipulating industrial yeast strains is less successful, probably due to the genome complexity and low copy numbers of gRNA expression plasmids. Here we developed an efficient CRISPR/Cas9 system for industrial yeast strain engineering by using our previously engineered plasmids with increased copy numbers. Four genes in both a diploid strain (Ethanol Red, 8 alleles in total) and a triploid strain (ATCC 4124, 12 alleles in total) were knocked out in a single step with 100% efficiency. This system was used to construct xylose-fermenting, lactate-producing industrial yeast strains, in which ALD6, PHO13, LEU2, and URA3 were disrupted in a single step followed by the introduction of a xylose utilization pathway and a lactate biosynthetic pathway on auxotrophic marker plasmids. The optimized CRISPR/Cas9 system provides a powerful tool for the development of industrial yeast based microbial cell factories. © 2018 Wiley Periodicals, Inc.

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

    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

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

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

    2013-11-05

    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.

  6. Scientific Opinion on the substantiation of health claims related to Saccharomyces cerevisiae var. boulardii CNCM I-1079 and defence against pathogenic gastro-intestinal microorganisms (ID 913, further assessment) pursuant to Article 13(1) of Regulation (EC) No 1924/2006

    Tetens, Inge

    . boulardii CNCM I-1079 and defence against pathogenic gastro-intestinal microorganisms. The food constituent that is the subject of the health claim, Saccharomyces cerevisiae var. boulardii CNCM I-1079, is sufficiently characterised. The claimed effect, defence against pathogenic gastro......-intestinal microorganisms, is a beneficial physiological effect. The proposed target population is the general population. The Panel notes that the evidence provided is not sufficient to establish that the strains Saccharomyces cerevisiae var. boulardii CNCM I-1079 and Saccharomyces cerevisiae var. boulardii Hansen CBS...... relationship has not been established between the consumption of Saccharomyces cerevisiae var. boulardii CNCM I-1079 and defence against pathogenic gastro-intestinal microorganisms....

  7. Interactions between Drosophila and its natural yeast symbionts-Is Saccharomyces cerevisiae a good model for studying the fly-yeast relationship?

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

    2015-01-01

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

  8. Cellar-Associated Saccharomyces cerevisiae Population Structure Revealed High-Level Diversity and Perennial Persistence at Sauternes Wine Estates

    Börlin, Marine; Venet, Pauline; Claisse, Olivier; Salin, Franck

    2016-01-01

    ABSTRACT Three wine estates (designated A, B, and C) were sampled in Sauternes, a typical appellation of the Bordeaux wine area producing sweet white wine. From those wine estates, 551 yeast strains were collected between 2012 and 2014, added to 102 older strains from 1992 to 2011 from wine estate C. All the strains were analyzed through 15 microsatellite markers, resulting in 503 unique Saccharomyces cerevisiae genotypes, revealing high genetic diversity and a low presence of commercial yeast starters. Population analysis performed using Fst genetic distance or ancestry profiles revealed that the two closest wine estates, B and C, which have juxtaposed vineyard plots and common seasonal staff, share more related isolates with each other than with wine estate A, indicating exchange between estates. The characterization of isolates collected 23 years ago at wine estate C in relation to recent isolates obtained at wine estate B revealed the long-term persistence of isolates. Last, during the 2014 harvest period, a temporal succession of ancestral subpopulations related to the different batches associated with the selective picking of noble rotted grapes was highlighted. IMPORTANCE High genetic diversity of S. cerevisiae isolates from spontaneous fermentation on wine estates in the Sauternes appellation of Bordeaux was revealed. Only 7% of all Sauternes strains were considered genetically related to specific commercial strains. The long-term persistence (over 20 years) of S. cerevisiae profiles on a given wine estate is highlighted. PMID:26969698

  9. Xylose Fermentation by Saccharomyces cerevisiae: Challenges and Prospects

    Danuza Nogueira Moysés

    2016-02-01

    Full Text Available Many years have passed since the first genetically modified Saccharomyces cerevisiae strains capable of fermenting xylose were obtained with the promise of an environmentally sustainable solution for the conversion of the abundant lignocellulosic biomass to ethanol. Several challenges emerged from these first experiences, most of them related to solving redox imbalances, discovering new pathways for xylose utilization, modulation of the expression of genes of the non-oxidative pentose phosphate pathway, and reduction of xylitol formation. Strategies on evolutionary engineering were used to improve fermentation kinetics, but the resulting strains were still far from industrial application. Lignocellulosic hydrolysates proved to have different inhibitors derived from lignin and sugar degradation, along with significant amounts of acetic acid, intrinsically related with biomass deconstruction. This, associated with pH, temperature, high ethanol, and other stress fluctuations presented on large scale fermentations led the search for yeasts with more robust backgrounds, like industrial strains, as engineering targets. Some promising yeasts were obtained both from studies of stress tolerance genes and adaptation on hydrolysates. Since fermentation times on mixed-substrate hydrolysates were still not cost-effective, the more selective search for new or engineered sugar transporters for xylose are still the focus of many recent studies. These challenges, as well as under-appreciated process strategies, will be discussed in this review.

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

    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.

  11. Endogenous lycopene improves ethanol production under acetic acid stress in Saccharomyces cerevisiae.

    Pan, Shuo; Jia, Bin; Liu, Hong; Wang, Zhen; Chai, Meng-Zhe; Ding, Ming-Zhu; Zhou, Xiao; Li, Xia; Li, Chun; Li, Bing-Zhi; Yuan, Ying-Jin

    2018-01-01

    Acetic acid, generated from the pretreatment of lignocellulosic biomass, is a significant obstacle for lignocellulosic ethanol production. Reactive oxidative species (ROS)-mediated cell damage is one of important issues caused by acetic acid. It has been reported that decreasing ROS level can improve the acetic acid tolerance of Saccharomyces cerevisiae . Lycopene is known as an antioxidant. In the study, we investigated effects of endogenous lycopene on cell growth and ethanol production of S. cerevisiae in acetic acid media. By accumulating endogenous lycopene during the aerobic fermentation of the seed stage, the intracellular ROS level of strain decreased to 1.4% of that of the control strain during ethanol fermentation. In the ethanol fermentation system containing 100 g/L glucose and 5.5 g/L acetic acid, the lag phase of strain was 24 h shorter than that of control strain. Glucose consumption rate and ethanol titer of yPS002 got to 2.08 g/L/h and 44.25 g/L, respectively, which were 2.6- and 1.3-fold of the control strain. Transcriptional changes of INO1 gene and CTT1 gene confirmed that endogenous lycopene can decrease oxidative stress and improve intracellular environment. Biosynthesis of endogenous lycopene is first associated with enhancing tolerance to acetic acid in S. cerevisiae . We demonstrate that endogenous lycopene can decrease intracellular ROS level caused by acetic acid, thus increasing cell growth and ethanol production. This work innovatively   puts forward a new strategy for second generation bioethanol production during lignocellulosic fermentation.

  12. Effect of initial ph on growth characteristics and fermentation properties of Saccharomyces cerevisiae.

    Liu, Xingyan; Jia, Bo; Sun, Xiangyu; Ai, Jingya; Wang, Lihua; Wang, Cheng; Zhao, Fang; Zhan, Jicheng; Huang, Weidong

    2015-04-01

    As the core microorganism of wine making, Saccharomyces cerevisiae encounter low pH stress at the beginning of fermentation. Effect of initial pH (4.50, 3.00, 2.75, 2.50) on growth and fermentation performance of 3 S. cerevisiae strains Freddo, BH8, Nº.7303, different tolerance at low pH, chosen from 12 strains, was studied. The values of yeast growth (OD600 , colony forming units, cell dry weight), fermentation efficiency (accumulated mass loss, change of total sugar concentration), and fermentation products (ethanol, glycerol, acetic acid, and l-succinic acid) at different pH stress were measured. The results showed that the initial pH of must was a vital factor influencing yeast growth and alcoholic fermentation. Among the 3 strains, strain Freddo and BH8 were more tolerant than Nº.7303, so they were affected slighter than the latter. Among the 4 pH values, all the 3 strains showed adaptation even at pH 2.50; pH 2.75 and 2.50 had more vital effect on yeast growth and fermentation products in contrast with pH 4.50 and 3.00. In general, low initial pH showed the properties of prolonging yeast lag phase, affecting accumulated mass loss, changing the consumption rate of total sugar, increasing final content of acetic acid and glycerol, and decreasing final content of ethanol and l- succinic acid, except some special cases. Based on this study, the effect of low pH on wine products would be better understood and the tolerance mechanism of low pH of S. cerevisiae could be better explored in future. © 2015 Institute of Food Technologists®

  13. Adaptive evolution of Saccharomyces cerevisiae with enhanced ethanol tolerance for Chinese rice wine fermentation.

    Chen, Shuang; Xu, Yan

    2014-08-01

    High tolerance towards ethanol is a desirable property for the Saccharomyces cerevisiae strains used in the alcoholic beverage industry. To improve the ethanol tolerance of an industrial Chinese rice wine yeast, a sequential batch fermentation strategy was used to adaptively evolve a chemically mutagenized Chinese rice wine G85 strain. The high level of ethanol produced under Chinese rice wine-like fermentation conditions was used as the selective pressure. After adaptive evolution of approximately 200 generations, mutant G85X-8 was isolated and shown to have markedly increased ethanol tolerance. The evolved strain also showed higher osmotic and temperature tolerances than the parental strain. Laboratory Chinese rice wine fermentation showed that the evolved G85X-8 strain was able to catabolize sugars more completely than the parental G85 strain. A higher level of yeast cell activity was found in the fermentation mash produced by the evolved strain, but the aroma profiles were similar between the evolved and parental strains. The improved ethanol tolerance in the evolved strain might be ascribed to the altered fatty acids composition of the cell membrane and higher intracellular trehalose concentrations. These results suggest that adaptive evolution is an efficient approach for the non-recombinant modification of industrial yeast strains.

  14. Ribosomal protein methyltransferases in the yeast Saccharomyces cerevisiae: Roles in ribosome biogenesis and translation.

    Al-Hadid, Qais; White, Jonelle; Clarke, Steven

    2016-02-12

    A significant percentage of the methyltransferasome in Saccharomyces cerevisiae and higher eukaryotes is devoted to methylation of the translational machinery. Methylation of the RNA components of the translational machinery has been studied extensively and is important for structure stability, ribosome biogenesis, and translational fidelity. However, the functional effects of ribosomal protein methylation by their cognate methyltransferases are still largely unknown. Previous work has shown that the ribosomal protein Rpl3 methyltransferase, histidine protein methyltransferase 1 (Hpm1), is important for ribosome biogenesis and translation elongation fidelity. In this study, yeast strains deficient in each of the ten ribosomal protein methyltransferases in S. cerevisiae were examined for potential defects in ribosome biogenesis and translation. Like Hpm1-deficient cells, loss of four of the nine other ribosomal protein methyltransferases resulted in defects in ribosomal subunit synthesis. All of the mutant strains exhibited resistance to the ribosome inhibitors anisomycin and/or cycloheximide in plate assays, but not in liquid culture. Translational fidelity assays measuring stop codon readthrough, amino acid misincorporation, and programmed -1 ribosomal frameshifting, revealed that eight of the ten enzymes are important for translation elongation fidelity and the remaining two are necessary for translation termination efficiency. Altogether, these results demonstrate that ribosomal protein methyltransferases in S. cerevisiae play important roles in ribosome biogenesis and translation. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Engineering a functional 1-deoxy-D-xylulose 5-phosphate (DXP) pathway in Saccharomyces cerevisiae

    Kirby, James [Univ. of California, Berkeley, CA (United States). California Institute of Quantitative Biosciences (QB3); Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Dietzel, Kevin L. [Amyris, inc., Emeryville, CA (United States); Wichmann, Gale [Amyris, inc., Emeryville, CA (United States); Chan, Rossana [Univ. of California, Berkeley, CA (United States). California Institute of Quantitative Biosciences (QB3); Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Antipov, Eugene [Amyris, inc., Emeryville, CA (United States); Moss, Nathan [Amyris, inc., Emeryville, CA (United States); Baidoo, Edward E. K. [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Jackson, Peter [Amyris, inc., Emeryville, CA (United States); Gaucher, Sara P. [Amyris, inc., Emeryville, CA (United States); Gottlieb, Shayin [Amyris, inc., Emeryville, CA (United States); LaBarge, Jeremy [Amyris, inc., Emeryville, CA (United States); Mahatdejkul, Tina [Amyris, inc., Emeryville, CA (United States); Hawkins, Kristy M. [Amyris, inc., Emeryville, CA (United States); Muley, Sheela [Amyris, inc., Emeryville, CA (United States); Newman, Jack D. [Amyris, inc., Emeryville, CA (United States); Liu, Pinghua [Boston Univ., MA (United States). Dept. of Chemistry; Keasling, Jay D. [Univ. of California, Berkeley, CA (United States). California Institute of Quantitative Biosciences (QB3); Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Univ. of California, Berkeley, CA (United States). Depts. of Chemical & Biomolecular Engineering and Bioengineering; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Biological Systems & Engineering Div.; Technical Univ. of Denmark, Hoesholm (Denmark). Novo Nodisk Foundation Center for Biosustainability; Zhao, Lishan [Amyris, inc., Emeryville, CA (United States)

    2016-10-27

    Isoprenoids are made by all free-living organisms and range from essential metabolites like sterols and quinones to more complex compounds like pinene and rubber. They are used in many commercial applications and much work has gone into engineering microbial hosts for their production. Isoprenoids are produced either from acetyl-CoA via the mevalonate pathway or from pyruvate and glyceraldehyde 3-phosphate via the 1-deoxy-D-xylulose 5-phosphate (DXP) pathway. Saccharomyces cerevisiae exclusively utilizes the mevalonate pathway to synthesize native isoprenoids and in fact the alternative DXP pathway has never been found or successfully reconstructed in the eukaryotic cytosol. There are, however, several advantages to isoprenoid synthesis via the DXP pathway, such as a higher theoretical yield, and it has long been a goal to transplant the pathway into yeast. In this work, we investigate and address barriers to DXP pathway functionality in S. cerevisiae using a combination of synthetic biology, biochemistry and metabolomics. We report, for the first time, functional expression of the DXP pathway in S. cerevisiae. Under low aeration conditions, an engineered strain relying solely on the DXP pathway for isoprenoid biosynthesis achieved an endpoint biomass 80% of that of the same strain using the mevalonate pathway.

  16. Atomic force microscopic study of the influence of physical stresses on Saccharomyces cerevisiae and Schizosaccharomyces pombe.

    Adya, Ashok K; Canetta, Elisabetta; Walker, Graeme M

    2006-01-01

    Morphological changes in the cell surfaces of the budding yeast Saccharomyces cerevisiae (strain NCYC 1681), and the fission yeast Schizosaccharomyces pombe (strain DVPB 1354), in response to thermal and osmotic stresses, were investigated using an atomic force microscope. With this microscope imaging, together with measurements of culture viability and cell size, it was possible to relate topological changes of the cell surface at nanoscale with cellular stress physiology. As expected, when the yeasts were exposed to thermostress or osmostress, their viability together with the mean cell volume decreased in conjunction with the increase in thermal or osmotic shock. Nevertheless, the viability of cells stressed for up to 1 h remained relatively high. For example, viabilities were >50% and >90% for the thermostressed, and >60% and >70% for the osmostressed S. cerevisiae and Schiz. pombe, respectively. Mean cell volume measurements, and bearing and roughness analyses of atomic force microscope images of stressed yeasts indicate that Schiz. pombe may be more resistant to physical stresses than S. cerevisiae. Overall, this study has highlighted the usefulness of atomic force microscope in studies of yeast stress physiology.

  17. Ecological and Genetic Barriers Differentiate Natural Populations of Saccharomyces cerevisiae.

    Clowers, Katie J; Heilberger, Justin; Piotrowski, Jeff S; Will, Jessica L; Gasch, Audrey P

    2015-09-01

    How populations that inhabit the same geographical area become genetically differentiated is not clear. To investigate this, we characterized phenotypic and genetic differences between two populations of Saccharomyces cerevisiae that in some cases inhabit the same environment but show relatively little gene flow. We profiled stress sensitivity in a group of vineyard isolates and a group of oak-soil strains and found several niche-related phenotypes that distinguish the populations. We performed bulk-segregant mapping on two of the distinguishing traits: The vineyard-specific ability to grow in grape juice and oak-specific tolerance to the cell wall damaging drug Congo red. To implicate causal genes, we also performed a chemical genomic screen in the lab-strain deletion collection and identified many important genes that fell under quantitative trait loci peaks. One gene important for growth in grape juice and identified by both the mapping and the screen was SSU1, a sulfite-nitrite pump implicated in wine fermentations. The beneficial allele is generated by a known translocation that we reasoned may also serve as a genetic barrier. We found that the translocation is prevalent in vineyard strains, but absent in oak strains, and presents a postzygotic barrier to spore viability. Furthermore, the translocation was associated with a fitness cost to the rapid growth rate seen in oak-soil strains. Our results reveal the translocation as a dual-function locus that enforces ecological differentiation while producing a genetic barrier to gene flow in these sympatric populations. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  18. Saccharomyces cerevisiae Boulardii Reduces the Deoxynivalenol-Induced Alteration of the Intestinal Transcriptome

    Imourana Alassane-Kpembi

    2018-05-01

    Full Text Available 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. Transcriptome response to alkane biofuels in Saccharomyces cerevisiae: identification of efflux pumps involved in alkane tolerance

    2013-01-01

    Background Hydrocarbon alkanes have been recently considered as important next-generation biofuels because microbial production of alkane biofuels was demonstrated. However, the toxicity of alkanes to microbial hosts can possibly be a bottleneck for high productivity of alkane biofuels. To tackle this toxicity issue, it is essential to understand molecular mechanisms of interactions between alkanes and microbial hosts, and to harness these mechanisms to develop microbial host strains with improved tolerance against alkanes. In this study, we aimed to improve the tolerance of Saccharomyces cerevisiae, a model eukaryotic host of industrial significance, to alkane biofuels by exploiting cellular mechanisms underlying alkane response. Results To this end, we first confirmed that nonane (C9), decane (C10), and undecane (C11) were significantly toxic and accumulated in S. cerevisiae. Transcriptome analyses suggested that C9 and C10 induced a range of cellular mechanisms such as efflux pumps, membrane modification, radical detoxification, and energy supply. Since efflux pumps could possibly aid in alkane secretion, thereby reducing the cytotoxicity, we formed the hypothesis that those induced efflux pumps could contribute to alkane export and tolerance. In support of this hypothesis, we demonstrated the roles of the efflux pumps Snq2p and Pdr5p in reducing intracellular levels of C10 and C11, as well as enhancing tolerance levels against C10 and C11. This result provided the evidence that Snq2p and Pdr5p were associated with alkane export and tolerance in S. cerevisiae. Conclusions Here, we investigated the cellular mechanisms of S. cerevisiae response to alkane biofuels at a systems level through transcriptome analyses. Based on these mechanisms, we identified efflux pumps involved in alkane export and tolerance in S. cerevisiae. We believe that the results here provide valuable insights into designing microbial engineering strategies to improve cellular tolerance for

  20. Characterization of the Viable but Nonculturable (VBNC State in Saccharomyces cerevisiae.

    Mohammad Salma

    Full Text Available The Viable But Non Culturable (VBNC state has been thoroughly studied in bacteria. In contrast, it has received much less attention in other microorganisms. However, it has been suggested that various yeast species occurring in wine may enter in VBNC following sulfite stress.In order to provide conclusive evidences for the existence of a VBNC state in yeast, the ability of Saccharomyces cerevisiae to enter into a VBNC state by applying sulfite stress was investigated. Viable populations were monitored by flow cytometry while culturable populations were followed by plating on culture medium. Twenty-four hours after the application of the stress, the comparison between the culturable population and the viable population demonstrated the presence of viable cells that were non culturable. In addition, removal of the stress by increasing the pH of the medium at different time intervals into the VBNC state allowed the VBNC S. cerevisiae cells to "resuscitate". The similarity between the cell cycle profiles of VBNC cells and cells exiting the VBNC state together with the generation rate of cells exiting VBNC state demonstrated the absence of cellular multiplication during the exit from the VBNC state. This provides evidence of a true VBNC state. To get further insight into the molecular mechanism pertaining to the VBNC state, we studied the involvement of the SSU1 gene, encoding a sulfite pump in S. cerevisiae. The physiological behavior of wild-type S. cerevisiae was compared to those of a recombinant strain overexpressing SSU1 and null Δssu1 mutant. Our results demonstrated that the SSU1 gene is only implicated in the first stages of sulfite resistance but not per se in the VBNC phenotype. Our study clearly demonstrated the existence of an SO2-induced VBNC state in S. cerevisiae and that the stress removal allows the "resuscitation" of VBNC cells during the VBNC state.

  1. Saccharomyces cerevisiae Boulardii Reduces the Deoxynivalenol-Induced Alteration of the Intestinal Transcriptome.

    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.

  2. Genome-Wide Requirements for Resistance to Functionally Distinct DNA-Damaging Agents.

    2005-08-01

    Full Text Available The mechanistic and therapeutic differences in the cellular response to DNA-damaging compounds are not completely understood, despite intense study. To expand our knowledge of DNA damage, we assayed the effects of 12 closely related DNA-damaging agents on the complete pool of ~4,700 barcoded homozygous deletion strains of Saccharomyces cerevisiae. In our protocol, deletion strains are pooled together and grown competitively in the presence of compound. Relative strain sensitivity is determined by hybridization of PCR-amplified barcodes to an oligonucleotide array carrying the barcode complements. These screens identified genes in well-characterized DNA-damage-response pathways as well as genes whose role in the DNA-damage response had not been previously established. High-throughput individual growth analysis was used to independently confirm microarray results. Each compound produced a unique genome-wide profile. Analysis of these data allowed us to determine the relative importance of DNA-repair modules for resistance to each of the 12 profiled compounds. Clustering the data for 12 distinct compounds uncovered both known and novel functional interactions that comprise the DNA-damage response and allowed us to define the genetic determinants required for repair of interstrand cross-links. Further genetic analysis allowed determination of epistasis for one of these functional groups.

  3. Genomic diversity of Saccharomyces cerevisiae yeasts associated with alcoholic fermentation of bacanora produced by artisanal methods.

    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.

  4. Major sulfonate transporter Soa1 in Saccharomyces cerevisiae and considerable substrate diversity in its fungal family

    Holt, Sylvester; Kankipati, Harish; De Graeve, Stijn

    2017-01-01

    Sulfate is a well-established sulfur source for fungi; however, in soils sulfonates and sulfate esters, especially choline sulfate, are often much more prominent. Here we show that Saccharomyces cerevisiae YIL166C(SOA1) encodes an inorganic sulfur (sulfate, sulfite and thiosulfate) transporter...... that also catalyses sulfonate and choline sulfate uptake. Phylogenetic analysis of fungal SOA1 orthologues and expression of 20 members in the sul1 Delta sul2 Delta soa1 Delta strain, which is deficient in inorganic and organic sulfur compound uptake, reveals that these transporters have diverse substrate...... preferences for sulfur compounds. We further show that SOA2, a S. cerevisiae SOA1 paralogue found in S. uvarum, S. eubayanus and S. arboricola is likely to be an evolutionary remnant of the uncharacterized open reading frames YOL163W and YOL162W. Our work highlights the importance of sulfonates and choline...

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

    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.

  6. Expression of protein engineered NADP{sup +}-dependent xylitol dehydrogenase increases ethanol production from xylose in recombinant Saccharomyces cerevisiae

    Matsushika, Akinori; Inoue, Hiroyuki; Murakami, Katsuji; Takimura, Osamu; Sawayama, Shigeki [National Institute of Advanced Industrial Science and Technology, Hiroshima (Japan). Biomass Technology Research Center; Watanabe, Seiya; Kodaki, Tsutomu; Makino, Keisuke [Kyoto Univ. (Japan). Inst. of Advanced Energy

    2008-11-15

    A recombinant Saccharomyces cerevisiae strain transformed with xylose reductase (XR) and xylitol dehydrogenase (XDH) genes from Pichia stipitis has the ability to convert xylose to ethanol together with the unfavorable excretion of xylitol, which may be due to cofactor imbalance between NADPH-preferring XR and NAD{sup +}-dependent XDH. To reduce xylitol formation, we have already generated several XDH mutants with a reversal of coenzyme specificity toward NADP{sup +}. In this study, we constructed a set of recombinant S. cerevisiae strains with xylose-fermenting ability, including protein-engineered NADP{sup +}-dependent XDH-expressing strains. The most positive effect on xylose-to-ethanol fermentation was found by using a strain named MA-N5, constructed by chromosomal integration of the gene for NADP{sup +}-dependent XDH along with XR and endogenous xylulokinase genes. The MA-N5 strain had an increase in ethanol production and decrease in xylitol excretion compared with the reference strain expressing wild-type XDH when fermenting not only xylose but also mixed sugars containing glucose and xylose. Furthermore, the MA-N5 strain produced ethanol with a high yield of 0.49 g of ethanol/g of total consumed sugars in the nonsulfuric acid hydrolysate of wood chips. The results demonstrate that glucose and xylose present in the lignocellulosic hydrolysate can be efficiently fermented by this redox-engineered strain. (orig.)

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

    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.

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

    Camila M.P.B.S. de Ponzzes-Gomes

    2014-06-01

    Full Text Available 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 x 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.

  9. Chromosome VIII disomy influences the nonsense suppression efficiency and transition metal tolerance of the yeast Saccharomyces cerevisiae.

    Zadorsky, S P; Sopova, Y V; Andreichuk, D Y; Startsev, V A; Medvedeva, V P; Inge-Vechtomov, S G

    2015-06-01

    The SUP35 gene of the yeast Saccharomyces cerevisiae encodes the translation termination factor eRF3. Mutations in this gene lead to the suppression of nonsense mutations and a number of other pleiotropic phenotypes, one of which is impaired chromosome segregation during cell division. Similar effects result from replacing the S. cerevisiae SUP35 gene with its orthologues. A number of genetic and epigenetic changes that occur in the sup35 background result in partial compensation for this suppressor effect. In this study we showed that in S. cerevisiae strains in which the SUP35 orthologue from the yeast Pichia methanolica replaces the S. cerevisiae SUP35 gene, chromosome VIII disomy results in decreased efficiency of nonsense suppression. This antisuppressor effect is not associated with decreased stop codon read-through. We identified SBP1, a gene that localizes to chromosome VIII, as a dosage-dependent antisuppressor that strongly contributes to the overall antisuppressor effect of chromosome VIII disomy. Disomy of chromosome VIII also leads to a change in the yeast strains' tolerance of a number of transition metal salts. Copyright © 2015 John Wiley & Sons, Ltd.

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

    Jennifer R Bellon

    Full Text Available 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.