Insect symbiosis: derivation of yeast-like endosymbionts within an entomopathogenic filamentous lineage.

Science.gov (United States)

Suh, S O; Noda, H; Blackwell, M

2001-06-01

Yeast-like endosymbionts (YLSs) of insects often are restricted to specific hosts and are essential to the host's survival. For example, in planthoppers (Homoptera: Delphacidae), endosymbionts function in sterol utilization and nitrogen recycling for the hosts. Our study, designed to investigate evolutionary changes in the YLS lineage involved in the planthopper association, strongly suggests an origin of the YLSs from within the filamentous ascomycetes (Euascomycetes), not the true yeasts (Saccharomycetes), as their morphology might indicate. During divergence of the planthopper YLSs, dramatic changes would have occurred in the insect-fungus interaction and the fungal morphology that have previously been undescribed in filamentous ascomycetes. Phylogenetic trees were based on individual and combined data sets of 2.6 kb of the nuclear small- and large-subunit ribosomal RNA genes for YLSs from three rice planthoppers (Laodelphax striatellus, Nilaparvata lugens, and Sogatella furcifera) compared with 56 other fungi. Parsimony analysis placed the planthopper YLSs within Cordyceps (Euascomycetes: Hypocreales: Clavicipitaceae), a genus of filamentous insects and a few fungal pathogenic ascomycetes. Another YLS species restricted to the aphid Hamiltonaphis styraci (Homoptera: Aphididae) was a sister taxon to the planthopper YLSS: Filamentous insect pathogens (Metarhizium and Beauveria) specific to the same species of insect hosts as the YLSs also formed lineages within the Clavicipitaceae, but these were distinct from the clade comprising YLS species. Trees constrained to include the YLSs in families of the Hypocreales other than the Clavicipitaceae were rejected by the Kishino-Hasegawa test. In addition, the results of this study support a hypothesis of two independent origins of insect-associated YLSs from among filamentous ascomycetes: the planthopper YLSs in the Clavicipitaceae and the YLSs associated with anobiid beetles (Symbiotaphrina species). Several lineages of

Fatty acids from oleaginous yeasts and yeast-like fungi and their potential applications.

Science.gov (United States)

Xue, Si-Jia; Chi, Zhe; Zhang, Yu; Li, Yan-Feng; Liu, Guang-Lei; Jiang, Hong; Hu, Zhong; Chi, Zhen-Ming

2018-02-01

Oleaginous yeasts, fatty acids biosynthesis and regulation in the oleaginous yeasts and the fatty acids from the oleaginous yeasts and their applications are reviewed in this article. Oleaginous yeasts such as Rhodosporidium toruloides, Yarrowia lipolytica, Rhodotorula mucilaginosa, and Aureobasidium melanogenum, which can accumulate over 50% lipid of their cell dry weight, have many advantages over other oleaginous microorganisms. The fatty acids from the oleaginous yeasts have many potential applications. Many oleaginous yeasts have now been genetically modified to over-produce fatty acids and their derivatives. The most important features of the oleaginous yeasts are that they have special enzymatic systems for enhanced biosynthesis and regulation of fatty acids in their lipid particles. Recently, some oleaginous yeasts such as R. toruloides have been found to have a unique fatty acids synthetase and other oleaginous yeasts such as A. melanogenum have a unique highly reducing polyketide synthase (HR-PKS) involved in the biosynthesis of hydroxyl fatty acids. It is necessary to further enhance lipid biosynthesis using metabolic engineering and explore new applications of fatty acids in biotechnology.

Comparative analysis of yeast-like species potentially useful to environmental biotechnology

Directory of Open Access Journals (Sweden)

Anna Grabińska-Łoniewska

2014-08-01

Full Text Available Five yeast-like species recommended for enhancing the bioremediation of wastewaters, soils and cxhaust gases contaminated with recalcitrant compounds were analysed with repect to their morphologal characteristics and physiology.

Evaluation of the ability of commercial wine yeasts to form biofilms (mats) and adhere to plastic: implications for the microbiota of the winery environment.

Science.gov (United States)

Tek, Ee Lin; Sundstrom, Joanna F; Gardner, Jennifer M; Oliver, Stephen G; Jiranek, Vladimir

2018-02-01

Commercially available active dried wine yeasts are regularly used by winemakers worldwide to achieve reliable fermentations and obtain quality wine. This practice has led to increased evidence of traces of commercial wine yeast in the vineyard, winery and uninoculated musts. The mechanism(s) that enables commercial wine yeast to persist in the winery environment and the influence to native microbial communities on this persistence is poorly understood. This study has investigated the ability of commercial wine yeasts to form biofilms and adhere to plastic. The results indicate that the biofilms formed by commercial yeasts consist of cells with a combination of different lifestyles (replicative and non-replicative) and growth modes including invasive growth, bud elongation, sporulation and a mat sectoring-like phenotype. Invasive growth was greatly enhanced on grape pulp regardless of strain, while adhesion on plastic varied between strains. The findings suggest a possible mechanism that allows commercial yeast to colonise and survive in the winery environment, which may have implications for the indigenous microbiota profile as well as the population profile in uninoculated fermentations if their dissemination is not controlled. © FEMS 2018. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Biotechnological Applications of Dimorphic Yeasts

Science.gov (United States)

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

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

[Effects of 33% grapefruit extract on the growth of the yeast--like fungi, dermatopytes and moulds].

Science.gov (United States)

Krajewska-Kułak, E; Lukaszuk, C; Niczyporuk, W

2001-01-01

Grapefruit seed extract was discovered by Jacob Harich an american immunologist in 1980. Assessment of the influence of grapefruit extract on the yeast-like fungi strains--Candida albicans growth. Material used in this investigation was ATCC test Candida albicans strains no 10231, 200 of Candida albicans strains, 5 of Candida sp. strains isolated from patients with candidiasis symptoms from different ontocenosis and 12 of dermatophytes and moulds isolated from patients. The susceptibility of the Candida was determined by serial dilution method. It seems that 33% grapefruit extract exert a potent antifungal activity against the yeast like fungi strains and had low activity against dermatophytes and moulds. Further studies in vitro and in vivo on greater number of the yeast-like fungi strains and other fungi species are needed.

Removal of Zn(II) from electroplating effluent using yeast biofilm formed on gravels: batch and column studies

Science.gov (United States)

2014-01-01

Background Present study deals with the removal of Zn(II) ions from effluent using yeast biofilm formed on gravels. Methods The biofilm forming ability of Candida rugosa and Cryptococcus laurentii was evaluated using XTT (2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide) reduction assay and monitored by scanning electron microscopy (SEM), and Confocal laser scanning microscopy (CLSM). Copious amount of extracellular polymeric substances (EPS) produced by yeast species was quantified and characterized by Fourier transform infrared spectroscopy (FT-IR). Results Yeast biofilm formed on gravels by C. rugosa and C. laurentii showed 88% and 74.2% removal of Zn(II) ions respectively in batch mode. In column mode, removal of Zn(II) ions from real effluent was found to be 95.29% by C. rugosa biofilm formed on gravels. Conclusion The results of the present study showed that there is a scope to develop a cost effective method for the efficient removal of Zn(II) from effluent using gravels coated with yeast biofilm. PMID:24397917

Synergetic effect of yeast cell-surface expression of cellulase and expansin-like protein on direct ethanol production from cellulose

Science.gov (United States)

2013-01-01

Background Numerous studies have examined the direct fermentation of cellulosic materials by cellulase-expressing yeast; however, ethanol productivity in these systems has not yet reached an industrial level. Certain microorganisms, such as the cellulolytic fungus Trichoderma reesei, produce expansin-like proteins, which have a cellulose-loosening effect that may increase the breakdown of cellulose. Here, to improve the direct conversion of cellulose to ethanol, yeast Saccharomyces cerevisiae co-displaying cellulase and expansin-like protein on the cell surface were constructed and examined for direct ethanol fermentation performance. Results The cellulase and expansin-like protein co-expressing strain showed 246 mU/g-wet cell of phosphoric acid swollen cellulose (PASC) degradation activity, which corresponded to 2.9-fold higher activity than that of a cellulase-expressing strain. This result clearly demonstrated that yeast cell-surface expressed cellulase and expansin-like protein act synergistically to breakdown cellulose. In fermentation experiments examining direct ethanol production from PASC, the cellulase and expansin-like protein co-expressing strain produced 3.4 g/L ethanol after 96 h of fermentation, a concentration that was 1.4-fold higher than that achieved by the cellulase-expressing strain (2.5 g/L). Conclusions The PASC degradation and fermentation ability of an engineered yeast strain was markedly improved by co-expressing cellulase and expansin-like protein on the cell surface. To our knowledge, this is the first report to demonstrate the synergetic effect of co-expressing cellulase and expansin-like protein on a yeast cell surface, which may be a promising strategy for constructing direct ethanol fermenting yeast from cellulose. PMID:23835302

Multicellular stalk-like structures in Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Engelberg, D.; Mimran, A.; Martinetto, H.; Otto, J.; Simchen, G.; Karin, M.; Fink, G.R.

1998-01-01

Stalk formation is a novel pattern of multicellular organization. Yeast cells which survive UV irradiation form colonies that grow vertically to form very long (0.5 to 3.0 cm) and thin (0.5 to 4 mm in diameter) multicellular structures. We describe the conditions required to obtain these stalk-like structures reproducibly in large numbers. Yeast mutants, mutated for control of cell polarity, developmental processes, UV response, and signal transduction cascades were tested and found capable of forming stalk-like structures. We suggest a model that explains the mechanism of stalk formation by mechanical environmental forces. We show that other microorganisms (Candida albicans, Schizosaccharomyces pombe, and Escherichia coli) also form stalks, suggesting that the ability to produce stalks may be a general property of microorganisms. Diploid yeast stalks sporulate at an elevated frequency, raising the possibility that the physiological role of stalks might be disseminating spores

A cytosolic cytochrome b 5-like protein in yeast cell accelerating the electron transfer from NADPH to cytochrome c catalyzed by Old Yellow Enzyme

International Nuclear Information System (INIS)

Nakagawa, Manabu; Yamano, Toshio; Kuroda, Kiyo; Nonaka, Yasuki; Tojo, Hiromasa; Fujii, Shigeru

2005-01-01

A 410-nm absorbing species which enhanced the reduction rate of cytochrome c by Old Yellow Enzyme (OYE) with NADPH was found in Saccharomyces cerevisiae. It was solubilized together with OYE by the treatment of yeast cells with 10% ethyl acetate. The purified species showed visible absorption spectra in both oxidized and reduced forms, which were the same as those of the yeast microsomal cytochrome b 5 . At least 14 amino acid residues of the N-terminal region coincided with those of yeast microsomal b 5 , but the protein had a lower molecular weight determined to be 12,600 by SDS-PAGE and 9775 by mass spectrometry. The cytochrome b 5 -like protein enhanced the reduction rate of cytochrome c by OYE, and a plot of the reduction rates against its concentration showed a sigmoidal curve with an inflexion point at 6 x 10 -8 M of the protein

High Temperature Effects on Yeast-like Endosymbiotes and Pesticide Resistance of the Small Brown Planthopper, Laodelphax striatellus

Directory of Open Access Journals (Sweden)

Xiao-jie ZHANG

2008-12-01

Full Text Available The newly-hatched nymphs of the small brown planthopper (SBPH, Laodelphax striatellus, including field and sensitive populations, were subjected to the high-temperature (35°C treatment. The number of yeast-like endosymbiotes in SBPH reduced by 23.47%–34.23%, 57.86%–61.51% and 88.96%–90.71% after the high-temperature treatment for 1 d, 2 d, and 3 d, respectively. However, the size of yeast-like endosymbiotes was not obviously affected. Resistance of SBPH to three insecticides (imidacloprid, chlorpyrifos and fipronil decreased with the increase of treatment time.

Thermal performance study of form-stable composite phase change material with polyacrylic

Science.gov (United States)

Kee, Shin Yiing; Munusamy, Yamuna; Ong, Kok Seng; Chee, Swee Yong; Sanmuggam, Shimalaa

2017-04-01

Phase change material (PCM) is one of the most popular and widely used as thermal energy storage material because it is able to absorb and release a large amount of latent heat during a phase change process over a narrow temperature range. In this work, the form-stable composite PCM was prepared by blending of PMMA and myristic acid in different weight percentage. PMMA was used as a supporting material while myristic acid was used as PCM. Theoretically, PCM can be encapsulated in the support material after blending. However, a small amount of liquid PCMs can leak out from supporting material due to the volume change in phase change process. Therefore, a form-stable composite PCM with polyacrylic coating was studied. Leakage test was carried out to determine the leakage percentage of the form-stable composite PCM. Fourier transform infrared spectroscopy (FTIR) was used to characterize the chemical compatibility of the form-stable PCM composite while differential scanning calorimetry (DSC) was used to study the melting, freezing point and the latent heat of melting and freezing for the form-stable composite PCM.

MALDI-TOF MS as a tool to identify foodborne yeasts and yeast-like fungi.

Science.gov (United States)

Quintilla, Raquel; Kolecka, Anna; Casaregola, Serge; Daniel, Heide M; Houbraken, Jos; Kostrzewa, Markus; Boekhout, Teun; Groenewald, Marizeth

2018-02-02

Since food spoilage by yeasts causes high economic losses, fast and accurate identifications of yeasts associated with food and food-related products are important for the food industry. In this study the efficiency of the matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify food related yeasts was evaluated. A CBS in-house MALDI-TOF MS database was created and later challenged with a blinded test set of 146 yeast strains obtained from food and food related products. Ninety eight percent of the strains were correctly identified with log score values>1.7. One strain, Mrakia frigida, gained a correct identification with a score value1.7. Ambiguous identifications were observed due to two incorrect reference mass spectra's found in the commercial database BDAL v.4.0, namely Candida sake DSM 70763 which was re-identified as Candida oleophila, and Candida inconspicua DSM 70631 which was re-identified as Pichia membranifaciens. MALDI-TOF MS can distinguish between most of the species, but for some species complexes, such as the Kazachstania telluris and Mrakia frigida complexes, MALDI-TOF MS showed limited resolution and identification of sibling species was sometimes problematic. Despite this, we showed that the MALDI-TOF MS is applicable for routine identification and validation of foodborne yeasts, but a further update of the commercial reference databases is needed. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Science.gov (United States)

Hubenova, Yolina; Georgiev, Danail; Mitov, Mario

2014-09-01

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

Cocoa butter-like lipid production ability of non-oleaginous and oleaginous yeasts under nitrogen-limited culture conditions.

Science.gov (United States)

Wei, Yongjun; Siewers, Verena; Nielsen, Jens

2017-05-01

Cocoa butter (CB) extracted from cocoa beans is the main raw material for chocolate production. However, growing chocolate demands and limited CB production has resulted in a shortage of CB supply. CB is mainly composed of three different kinds of triacylglycerols (TAGs), POP (C16:0-C18:1-C16:0), POS (C16:0-C18:1-C18:0), and SOS (C18:0-C18:1-C18:0). The storage lipids of yeasts, mainly TAGs, also contain relative high-level of C16 and C18 fatty acids and might be used as CB-like lipids (CBL). In this study, we cultivated six different yeasts, including one non-oleaginous yeast strain, Saccharomyces cerevisiae CEN.PK113-7D, and five oleaginous yeast strains, Trichosporon oleaginosus DSM11815, Rhodotorula graminis DSM 27356, Lipomyces starkeyi DSM 70296, Rhodosporidium toruloides DSM 70398, and Yarrowia lipolytica CBS 6124, in nitrogen-limited medium and compared their CBL production ability. Under the same growth conditions, we found that TAGs were the main lipids in all six yeasts and that T. oleaginosus can produce more TAGs than the other five yeasts. Less than 3% of the total TAGs were identified as potential SOS in the six yeasts. However, T. oleaginosus produced 27.8% potential POP and POS at levels of 378 mg TAGs/g dry cell weight, hinting that this yeast may have potential as a CBL production host after further metabolic engineering in future.

Palmitic acid/polypyrrole composites as form-stable phase change materials for thermal energy storage

International Nuclear Information System (INIS)

Silakhori, Mahyar; Metselaar, Hendrik Simon Cornelis; Mahlia, Teuku Meurah Indra; Fauzi, Hadi; Baradaran, Saeid; Naghavi, Mohammad Sajad

2014-01-01

Highlights: • A novel phase change composite of palmitic acid–polypyrrole(PA–PPy) was fabricated. • Thermal properties of PA–PPy are characterized in different mass ratios of PA–PPy. • Thermal cycling test showed that form stable PCM had a favorable thermal reliability. - Abstract: In this study a novel palmitic acid (PA)/polypyrrole (PPy) form-stable PCMs were readily prepared by in situ polymerization method. PA was used as thermal energy storage material and PPy was operated as supporting material. Form-stable PCMs were investigated by SEM (scanning electron microscopy) and FTIR (Fourier transform infrared spectrometer) analysis that illustrated PA Particles were wrapped by PPy particles. XRD (X-ray diffractometer) was used for crystalline phase of PA/PPy composites. Thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC) were used for investigating Thermal stability and thermal energy storage properties of prepared form-stable PCMs. According to the obtained results the form stable PCMs exhibited favorable thermal stability in terms of their phase change temperature. The form-stable PCMs (79.9 wt% loading of PA) were considered as the highest loading PCM with desirable latent heat storage of 166.3 J/g and good thermal stability. Accelerated thermal cycling tests also showed that form stable PCM had an acceptable thermal reliability. As a consequence of acceptable thermal properties, thermal stability and chemical stability, we can consider the new kind of form stable PCMs for low temperature solar thermal energy storage applications

Air-stable complementary-like circuits based on organic ambipolar transistors

NARCIS (Netherlands)

Anthopoulos, Thomas D.; Setayesh, Sepas; Smits, Edsger; Cantatore, Eugenio; Boer ,de Bert; Blom, Paul W. M.; de Leeuw, Dago M.; Cölle, Michael

2006-01-01

Air stable complementary-like circuits, such as voltage inverters (see figure) and ring oscillators, are fabricated using ambipolar organic transistors based on a nickel dithiolene derivative. In addition to the complementary-like character of the circuits, the technology is very simple and fully

Flor Yeast: New Perspectives Beyond Wine Aging

Science.gov (United States)

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

2016-01-01

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

Search of yeast-like fungi in some lakes of the Tucholski Landscape Park (NW Poland

Directory of Open Access Journals (Sweden)

Anna Rózga

2014-08-01

Full Text Available The occurrence of pathogenic yeast-like fungi was determined in the catchment of the Suska and Raciąska Struga. Fourteen strains of fungi from 3 genera were isolated: Candida inconspicua, C. lambica, C. glabrata, Rhodotorula rubra, Rh. glutinls and Trichosporon capitatum.

Classification of Cryptococcus neoformans and yeast-like fungus isolates from pigeon droppings by colony phenotyping and ITS genotyping and their seasonal variations in Korea.

Science.gov (United States)

Chae, H S; Jang, G E; Kim, N H; Son, H R; Lee, J H; Kim, S H; Park, G N; Jo, H J; Kim, J T; Chang, K S

2012-03-01

Cryptococcus neoformans (C neoformans) is a frequent cause of invasive fungal disease in immunocompromised human hosts. Ninety-eight samples of pigeon droppings were collected from the pigeon shelters in Seoul, and cultured on birdseed agar (BSA) and Sabouraud dextrose agar (SDA). One hundred yeast-like colonies were selected and identified via phenotype characteristics, such as colony morphology and biochemical characteristics. This was then followed with genotyping via sequencing of the internal transcribed spacer (ITS) region. The colonies were classified into four kinds of colony color types: brown type (BrT), beige type (BeT), pink type (PT), and white type (WT). Numbers of isolated BrT, BeT, PT, and WT colonies were 22 (22%), 30 (30%), 19 (19%), and 39 (39%), respectively. All BrT colonies were identified as C neoformans. BeT were identified as 19 isolates of Cryptococcus laurentii, 10 isolates of Malassezia furfur, and 1 isolate of Cryptococcus uniguttulatus. PT was divided into two colony color types: light-PT (l-PT) and deep-PT (d-PT). Eighteen of l-PT and one of d-PT were identified as Rhodotorula glutinis and Rhodotorula mucilaginosa, respectively. WT were identified as 34 isolates of Cryptococcus guilliermondii, 3 isolates of Cryptococcus zeylanoides, 1 isolate of Cryptococcus sake, and 1 isolate of Stephanoascus ciferrii. Most strains were classified identically with the use of either phenotype or genotyping techniques, but C uniguttulatus and C sake classified by phenotyping were Pseudozyma aphidis and Cryptococcus famata by genotyping. This rapid screening technique of pathogenic yeast-like fungi by only colony characteristics is also expected to be very useful for primary yeast screening. Additionally, we investigated the seasonal variations of C neoformans and other yeast-like fungi from 379 pigeon-dropping samples that were collected from February 2011 to March 2011. We isolated 685 yeast-like fungi from the samples. Almost all C neoformans and

The Candida albicans stress response gene Stomatin-Like Protein 3 is implicated in ROS-induced apoptotic-like death of yeast phase cells.

Directory of Open Access Journals (Sweden)

Karen A Conrad

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

Target-like pigmentation after minipunch grafting in stable vitiligo

Directory of Open Access Journals (Sweden)

Nelee Bisen

2014-01-01

Full Text Available Surgical treatment for vitiligo has been ever evolving. Each surgical modality has its own benefits and limitations. Miniature punch grafting is the most extensively performed surgery, which gives good results in stable vitiligo. Herein we report an unusual type of repigmentation observed after minipunch grafting in a patient of stable vitiligo, which resembled target-like lesions with a "perigraft halo" surrounding individual grafts. Such pigment spread occurred despite the use of 0.5 mm larger graft from the donor site.

[Yeast-like fungi in the gastrointestinal tract in children and adolescents with diabetes type 1].

Science.gov (United States)

Kowalewska, Beata; Kawko, Małgorzata; Zorena, Katarzyna; Myśliwiec, Małgorzata

2015-01-01

In recent years the frequency of fungal infections in human populations has increased considerably. The most common type offungus attacking the human organism is Candida albicans. Yeast-like fungi occur naturally in the oral cavity, intestines, vagina, or skin, however in amounts not dangerous to human health. The studies so far have shown that patients with diabetes type 1 (T1DM) to a large degree are exposed to complications related to fungal infections. A substantial growth of fungi observed in diabetic patients may unfavorably affect metabolic compensation, and lead to increased demand for insulin, as well as to the difficult to cure symptom infections. The weaker the immune resistance in patients with diabetes, the greater the risk of ailments related to candidiasis. The article contains a review of recent literature regarding the problems related to occurrence of yeast-like fungi in digestive tract of children with diabetes type 1. © Polish Society for Pediatric Endocrinology and Diabetology.

Yeast prions: structure, biology, and prion-handling systems.

Science.gov (United States)

Wickner, Reed B; Shewmaker, Frank P; Bateman, David A; Edskes, Herman K; Gorkovskiy, Anton; Dayani, Yaron; Bezsonov, Evgeny E

2015-03-01

A prion is an infectious protein horizontally transmitting a disease or trait without a required nucleic acid. Yeast and fungal prions are nonchromosomal genes composed of protein, generally an altered form of a protein that catalyzes the same alteration of the protein. Yeast prions are thus transmitted both vertically (as genes composed of protein) and horizontally (as infectious proteins, or prions). Formation of amyloids (linear ordered β-sheet-rich protein aggregates with β-strands perpendicular to the long axis of the filament) underlies most yeast and fungal prions, and a single prion protein can have any of several distinct self-propagating amyloid forms with different biological properties (prion variants). Here we review the mechanism of faithful templating of protein conformation, the biological roles of these prions, and their interactions with cellular chaperones, the Btn2 and Cur1 aggregate-handling systems, and other cellular factors governing prion generation and propagation. Human amyloidoses include the PrP-based prion conditions and many other, more common amyloid-based diseases, several of which show prion-like features. Yeast prions increasingly are serving as models for the understanding and treatment of many mammalian amyloidoses. Patients with different clinical pictures of the same amyloidosis may be the equivalent of yeasts with different prion variants. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Activation of waste brewer's yeast Saccharomyces cerevisiae for bread production

OpenAIRE

Popov Stevan D.; Dodić Siniša N.; Mastilović Jasna S.; Dodić Jelena M.; Popov-Raljić Jovanka V.

2005-01-01

The waste brewer's yeast S. cerevisiae (activated and non-activated) was compared with the commercial baker's yeast regarding the volume of developed gas in dough, volume and freshness stability of produced bread. The activation of waste brewer's yeast resulted in the increased volume of developed gas in dough by 100% compared to non-activated brewer's yeast, and the obtained bread is of more stable freshness compared to bread produced with baker's yeast. The activation of BY affects positive...

Bactericidal activity of culture fluid components of Lactobacillus fermentum strain 90 TS-4 (21) clone 3, and their capacity to modulate adhesion of Candida albicans yeast-like fungi to vaginal epithelial cells.

Science.gov (United States)

Anokhina, I V; Kravtsov, E G; Protsenko, A V; Yashina, N V; Yermolaev, A V; Chesnokova, V L; Dalin, M V

2007-03-01

Antagonistic activities of L. fermentum strain 90 TS-4 (21), L. casei ATCC 27216, and L. acidophilus ATCC 4356 and bactericidal activity of lactobacillus culture fluid towards E. coli strain K12, S. aureus, and S. epidermidis test cultures were studied. The bactericidal effect of L. fermentum strain 90 TS-4 (21) clone 3 culture fluid preparation (pH 6.0) on the test cultures was dose-dependent. Adhesion of C. albicans yeast-like fungi to vaginal epitheliocytes was more pronounced for strains isolated from women with asymptomatic infection than for strains isolated from women with manifest forms. L. fermentum strain 90 TS-4 (21) clone 3 culture fluid preparation modulated adhesion of yeast-like fungi only if the fungal strain was initially highly adherent.

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

Science.gov (United States)

Palková, Zdena; Váchová, Libuše

2016-09-01

Yeasts, historically considered to be single-cell organisms, are able to activate different differentiation processes. Individual yeast cells can change their life-styles by processes of phenotypic switching such as the switch from yeast-shaped cells to filamentous cells (pseudohyphae or true hyphae) and the transition among opaque, white and gray cell-types. Yeasts can also create organized multicellular structures such as colonies and biofilms, and the latter are often observed as contaminants on surfaces in industry and medical care and are formed during infections of the human body. Multicellular structures are formed mostly of stationary-phase or slow-growing cells that diversify into specific cell subpopulations that have unique metabolic properties and can fulfill specific tasks. In addition to the development of multiple protective mechanisms, processes of metabolic reprogramming that reflect a changed environment help differentiated individual cells and/or community cell constituents to survive harmful environmental attacks and/or to escape the host immune system. This review aims to provide an overview of differentiation processes so far identified in individual yeast cells as well as in multicellular communities of yeast pathogens of the Candida and Cryptococcus spp. and the Candida albicans close relative, Saccharomyces cerevisiae. Molecular mechanisms and extracellular signals potentially involved in differentiation processes are also briefly mentioned. Copyright © 2016 Elsevier Ltd. All rights reserved.

Yeast Ivy1p Is a Putative I-BAR-domain Protein with pH-sensitive Filament Forming Ability in vitro.

Science.gov (United States)

Itoh, Yuzuru; Kida, Kazuki; Hanawa-Suetsugu, Kyoko; Suetsugu, Shiro

2016-01-01

Bin-Amphiphysin-Rvs161/167 (BAR) domains mold lipid bilayer membranes into tubules, by forming a spiral polymer on the membrane. Most BAR domains are thought to be involved in forming membrane invaginations through their concave membrane binding surfaces, whereas some members have convex membrane binding surfaces, and thereby mold membranes into protrusions. The BAR domains with a convex surface form a subtype called the inverse BAR (I-BAR) domain or IRSp53-MIM-homology domain (IMD). Although the mammalian I-BAR domains have been studied, those from other organisms remain elusive. Here, we found putative I-BAR domains in Fungi and animal-like unicellular organisms. The fungal protein containing the putative I-BAR-domain is known as Ivy1p in yeast, and is reportedly localized in the vacuole. The phylogenetic analysis of the I-BAR domains revealed that the fungal I-BAR-domain containing proteins comprise a distinct group from those containing IRSp53 or MIM. Importantly, Ivy1p formed a polymer with a diameter of approximately 20 nm in vitro, without a lipid membrane. The filaments were formed at neutral pH, but disassembled when pH was reverted to basic. Moreover, Ivy1p and the I-BAR domain expressed in mammalian HeLa cells was localized at a vacuole-like structure as filaments as revealed by super-resolved microscopy. These data indicate the pH-sensitive polymer forming ability and the functional conservation of Ivy1p in eukaryotic cells.

Attenuation of yeast form of Paracoccidioides Brasiliensis by gamma irradiation; Atenuacao da forma leveduriforme do Paraccocidioides Brasiliensis por irradicao gama

Energy Technology Data Exchange (ETDEWEB)

Demicheli, Marina Cortez

2006-07-01

Paracoccidioides brasiliensis is the agent of paracoccidioidomycosis, the most prevalent mycosis in Latin America, and currently there is no effective vaccine. The aim of this work was to attenuate the yeast form of P. brasiliensis by gamma irradiation for further studies on vaccine research. P. brasiliensis (strain Pb-18) cultures were irradiated at doses between 0.5 and 8.0 kGy. After each dose the fungal cells were plated and after 10 days the colony forming units (CFU) counted. The viability of the irradiated cells was measured using the dyes Janus green and methylene blue, and protein synthesis by incorporation of L {sup 35}S methionine. The comparison between the antigenic profile of irradiated and control yeast was made by Western blot and the virulence evaluated by the inoculation in C{sub 57}Bl/J6 and Balb/c mice. Morphological changes in irradiated yeast were evaluated by electronic microscopy and DNA integrity by electrophoresis in agarose gel. At 6.5 kGy the yeast lost the reproductive capacity. The viability and the incorporation of L- {sup 35}S methionine were the same in control and up to 6.5 kGy irradiated cells, but 6.5 kGy irradiated yeast secreted 40% less proteins. The Western blot profile was clearly similar in control and 6.5 kGy irradiated yeast. No CFU could be recovered from the tissues of the mice infected with the radio attenuated yeast. At the dose of 6.5 kGy the DNA was degraded and this damage was not repaired. The transmission electronic microscopy showed significant alterations in the nucleus of the irradiated cells. The scanning electronic microscopy showed that two hours after the irradiation the cells were collapsed or presented deep folds in the surface, however these injury were reversible. We concluded that for P. brasiliensis yeast cells it was possible to find a dose in which the pathogen loses its reproductive ability and virulence, while retaining its viability, metabolic activity and the antigenic profile. (author)

Yeast-like fungi possessing bio-indicator properties isolated from the Łyna river

Directory of Open Access Journals (Sweden)

Maria Dynowska

2014-08-01

Full Text Available Yeast-like fungi isolated in the Łyna river are constant components of microflora of inland waters. Every increase in their number indicates progress in the process of eutrophication and accumulation of organic and inorganic pollutans. The fungi Candida aibicans, Pichia guilliermondii, P. anomala, Rhodotorula glutinis i Trichosporon beigelii, potentially pathogenic apperred in water with high content of municipal sewage, but T. aquatile - in the clean waters only. The tested fungi can be also considered as bio-indicators.

Fabrication of TiO2@Yeast-Carbon Hybrid Composites with the Raspberry-Like Structure and Their Synergistic Adsorption-Photocatalysis Performance

Directory of Open Access Journals (Sweden)

Dang Yu

2013-01-01

Full Text Available In the present work, we report the preparation and photocatalytic properties of TiO2@yeast-carbon with raspberry-like structure using a pyrolysis method. The products are characterized by field emission scanning electron microscopy (FE-SEM, energy dispersive spectrometry (EDS, X-ray diffraction (XRD, thermal gravimetric and differential thermal analysis (TGA-DTA, Fourier transformed infrared spectroscopy (FT-IR, and ultraviolet visible spectroscopy (UV-VIS, respectively. The results show that the hybrid TiO2@yeast-carbon microspheres have ordered elliptic shapes of uniform size (length = 3.5±0.3 μm; width = 2.5±0.5 μm. UV-VIS ascertains that the as-prepared microspheres possess an obvious light response in a wide range of 250–400 nm. In the decomposition of typical model pollutants including methylene blue and congo red, the hybrid composites exhibited excellent photocatalytic activity for the methylene blue due to the enhanced adsorption ability. Further investigation reveals that the combined effect of adsorption from the yeast-carbon core and photocatalytic degradation from the attached TiO2 nanoparticles were responsible for the improvement of the photocatalytic activities. Hereby, the raspberry-like TiO2@yeast-carbon has promising applications in water purification.

Binding properties of SUMO-interacting motifs (SIMs) in yeast.

Science.gov (United States)

Jardin, Christophe; Horn, Anselm H C; Sticht, Heinrich

2015-03-01

Small ubiquitin-like modifier (SUMO) conjugation and interaction play an essential role in many cellular processes. A large number of yeast proteins is known to interact non-covalently with SUMO via short SUMO-interacting motifs (SIMs), but the structural details of this interaction are yet poorly characterized. In the present work, sequence analysis of a large dataset of 148 yeast SIMs revealed the existence of a hydrophobic core binding motif and a preference for acidic residues either within or adjacent to the core motif. Thus the sequence properties of yeast SIMs are highly similar to those described for human. Molecular dynamics simulations were performed to investigate the binding preferences for four representative SIM peptides differing in the number and distribution of acidic residues. Furthermore, the relative stability of two previously observed alternative binding orientations (parallel, antiparallel) was assessed. For all SIMs investigated, the antiparallel binding mode remained stable in the simulations and the SIMs were tightly bound via their hydrophobic core residues supplemented by polar interactions of the acidic residues. In contrary, the stability of the parallel binding mode is more dependent on the sequence features of the SIM motif like the number and position of acidic residues or the presence of additional adjacent interaction motifs. This information should be helpful to enhance the prediction of SIMs and their binding properties in different organisms to facilitate the reconstruction of the SUMO interactome.

'Killer' character of yeasts isolated from ethanolic fermentations

Directory of Open Access Journals (Sweden)

Ceccato-Antonini Sandra Regina

1999-01-01

Full Text Available The number of killer, neutral and sensitive yeasts was determined from strains isolated from substrates related to alcoholic fermentations. From 113 isolates, 24 showed killer activity against NCYC 1006 (standard sensitive strain, while 30 were sensitive to NCYC 738 (standard killer strain, and 59 had no reaction in assays at 25-27°C. Two wild yeast strains of Saccharomyces cerevisiae and one of Candida colliculosa were tested against 10 standard killer strains and one standard sensitive strain in a cell x cell and well-test assays at four different pHs. None of the isolates displayed strong killer activity or were sensitive to the standard strains. All belonged to the neutral type. It was concluded that although the number of killer strains was high, this character cannot be used to protect ethanol fermentation processes against yeast contaminants like those which form cell clusters.

The Fermentative and Aromatic Ability of Kloeckera and Hanseniaspora Yeasts

Science.gov (United States)

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

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

The production and growth characteristics of yeast and mycelial forms of Candida albicans in continuous culture.

Science.gov (United States)

Shepherd, M G; Sullivan, P A

1976-04-01

The growth characteristics of Candida albicans CM145,348 have been examined under aerobic conditions in continuous culture. At different steady states the environment was controlled with respect to the concentrations of dissolved oxygen, carbon and nitrogen, the pH, and the temperature. Dry matter, substrate concentration, yield, specific oxygen uptake, specific carbon dioxide release and respiration quotient were examined as a function of the dilution rate. The morphology depended on the carbon source. Maltose produced a mycelial morphology, whereas with lactate a yeast culture was obtained. With fructose or glucose as a carbon source a mixed morphology of yeast, pseudo-mycelial and mycelial forms was produced. A larger number of different growth conditions were examined in batch culture but a mixed morphology was always obtained.

The role of lager beer yeast in oxidative stability of model beer

DEFF Research Database (Denmark)

Berner, Torben Sune; Arneborg, Nils

2012-01-01

that the oxidative stress resistance was strain dependent. Fermentation of model wort in European Brewing Convention tubes using three yeast strains with varying oxidative stress resistances resulted in three model beers with different rates of radical formation as measured by electron spin resonance in forced......AIMS: In this study, we investigated the relationship between the ability of lager brewing yeast strains to tolerate oxidative stress and their ability to produce oxidative stable model beer. METHODS AND RESULTS: Screening of 21 lager brewing yeast strains against diamide and paraquat showed...... in the model beers. CONCLUSIONS: A more oxidative stable beer is not obtained by a more-oxidative-stress-tolerant lager brewing yeast strain, exhibiting a higher secretion of thioredoxin, but rather by a less-oxidative-stress-tolerant strain, exhibiting a higher iron uptake. SIGNIFICANCE AND IMPACT...

Genomics and the making of yeast biodiversity

NARCIS (Netherlands)

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

2015-01-01

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

An application of wastewater treatment in a cold environment and stable lipase production of Antarctic basidiomycetous yeast Mrakia blollopis.

Directory of Open Access Journals (Sweden)

Masaharu Tsuji

Full Text Available Milk fat curdle in sewage is one of the refractory materials for active sludge treatment under low temperature conditions. For the purpose of solving this problem by using a bio-remediation agent, we screened Antarctic yeasts and isolated SK-4 strain from algal mat of sediments of Naga-ike, a lake in Skarvsnes, East Antarctica. The yeast strain showed high nucleotide sequence homologies (>99.6% to Mrakia blollopis CBS8921(T in ITS and D1/D2 sequences and had two unique characteristics when applied on an active sludge; i.e., it showed a potential to use various carbon sources and to grow under vitamin-free conditions. Indeed, it showed a biochemical oxygen demand (BOD removal rate that was 1.25-fold higher than that of the control. We considered that the improved BOD removal rate by applying SK-4 strain was based on its lipase activity and characteristics. Finally, we purified the lipase from SK-4 and found that the enzyme was quite stable under wide ranges of temperatures and pH, even in the presence of various metal ions and organic solvents. SK-4, therefore, is a promising bio-remediation agent for cleaning up unwanted milk fat curdles from dairy milk wastewater under low temperature conditions.

Properties of the intracellular transient receptor potential (TRP) channel in yeast, Yvc1.

Science.gov (United States)

Chang, Yiming; Schlenstedt, Gabriel; Flockerzi, Veit; Beck, Andreas

2010-05-17

Transient receptor potential (TRP) channels are found among mammals, flies, worms, ciliates, Chlamydomonas, and yeast but are absent in plants. These channels are believed to be tetramers of proteins containing six transmembrane domains (TMs). Their primary structures are diverse with sequence similarities only in some short amino acid sequence motifs mainly within sequences covering TM5, TM6, and adjacent domains. In the yeast genome, there is one gene encoding a TRP-like sequence. This protein forms an ion channel in the vacuolar membrane and is therefore called Yvc1 for yeast vacuolar conductance 1. In the following we summarize its prominent features. Copyright 2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Yeast: An Overlooked Component of Bactrocera tryoni (Diptera: Tephritidae) Larval Gut Microbiota.

Science.gov (United States)

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

2017-02-01

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

Accelerating Yeast Prion Biology using Droplet Microfluidics

Science.gov (United States)

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

2012-02-01

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

Identification of microRNA-like RNAs in mycelial and yeast phases of the thermal dimorphic fungus Penicillium marneffei.

Directory of Open Access Journals (Sweden)

Susanna K P Lau

Full Text Available BACKGROUND: Penicillium marneffei is the most important thermal dimorphic fungus causing systemic mycosis in China and Southeast Asia. While miRNAs are increasingly recognized for their roles in post-transcriptional regulation of gene expression in animals and plants, miRNAs in fungi were less well studied and their potential roles in fungal dimorphism were largely unknown. Based on P. marneffei genome sequence, we hypothesize that miRNA-like RNAs (milRNAs may be expressed in the dimorphic fungus. METHODOLOGY/PRINCIPAL FINDINGS: We attempted to identify milRNAs in P. marneffei in both mycelial and yeast phase using high-throughput sequencing technology. Small RNAs were more abundantly expressed in mycelial than yeast phase. Sequence analysis revealed 24 potential milRNA candidates, including 17 candidates in mycelial and seven in yeast phase. Two genes, dcl-1 and dcl-2, encoding putative Dicer-like proteins and the gene, qde-2, encoding Argonaute-like protein, were identified in P. marneffei. Phylogenetic analysis showed that dcl-2 of P. marneffei was more closely related to the homologues in other thermal dimorphic pathogenic fungi than to Penicillium chrysogenum and Aspergillus spp., suggesting the co-evolution of dcl-2 among the thermal dimorphic fungi. Moreover, dcl-2 demonstrated higher mRNA expression levels in mycelial than yeast phase by 7 folds (P<0.001. Northern blot analysis confirmed the expression of two milRNAs, PM-milR-M1 and PM-milR-M2, only in mycelial phase. Using dcl-1(KO, dcl-2(KO, dcl(DKO and qde-2(KO deletion mutants, we showed that the biogenesis of both milRNAs were dependent on dcl-2 but not dcl-1 or qde-2. The mRNA expression levels of three predicted targets of PM-milR-M1 were upregulated in knockdown strain PM-milR-M1 (KD, supporting regulatory function of milRNAs. CONCLUSIONS/SIGNIFICANCE: Our findings provided the first evidence for differential expression of milRNAs in different growth phases of thermal dimorphic

Evaluation of Gene Modification Strategies for the Development of Low-Alcohol-Wine Yeasts

Science.gov (United States)

Kutyna, D. R.; Solomon, M. R.; Black, C. A.; Borneman, A.; Henschke, P. A.; Pretorius, I. S.; Chambers, P. J.

2012-01-01

Saccharomyces cerevisiae has evolved a highly efficient strategy for energy generation which maximizes ATP energy production from sugar. This adaptation enables efficient energy generation under anaerobic conditions and limits competition from other microorganisms by producing toxic metabolites, such as ethanol and CO2. Yeast fermentative and flavor capacity forms the biotechnological basis of a wide range of alcohol-containing beverages. Largely as a result of consumer demand for improved flavor, the alcohol content of some beverages like wine has increased. However, a global trend has recently emerged toward lowering the ethanol content of alcoholic beverages. One option for decreasing ethanol concentration is to use yeast strains able to divert some carbon away from ethanol production. In the case of wine, we have generated and evaluated a large number of gene modifications that were predicted, or known, to impact ethanol formation. Using the same yeast genetic background, 41 modifications were assessed. Enhancing glycerol production by increasing expression of the glyceraldehyde-3-phosphate dehydrogenase gene, GPD1, was the most efficient strategy to lower ethanol concentration. However, additional modifications were needed to avoid negatively affecting wine quality. Two strains carrying several stable, chromosomally integrated modifications showed significantly lower ethanol production in fermenting grape juice. Strain AWRI2531 was able to decrease ethanol concentrations from 15.6% (vol/vol) to 13.2% (vol/vol), whereas AWRI2532 lowered ethanol content from 15.6% (vol/vol) to 12% (vol/vol) in both Chardonnay and Cabernet Sauvignon juices. Both strains, however, produced high concentrations of acetaldehyde and acetoin, which negatively affect wine flavor. Further modifications of these strains allowed reduction of these metabolites. PMID:22729542

Auxotrophy-stimulated sensitivity to quaternary ammonium salts and its relation to active transport in yeast

International Nuclear Information System (INIS)

Lachowicz, T.M.; Oblak, E.; Piatkowski, J.

1992-01-01

In previous studies we have observed that auxotrophic mutants of yeast were much more sensitive to quaternary ammonium salts than the corresponding isogenic wild type strains. The super sensitivity of the auxotrophs seems to be a characteristic feature of yeast and yeast-like microorganisms: the level of sensitivity of the quaternary ammonium salts of the bacterial auxotrophs and their original prototrophic forms appeared to be the same. The super sensitivity of yeast auxotrophs disappeared on minimal media with ammonium as a nitrogen source. In this report there are presented the data indicating that enrichment of the minimal medium with arginine restores the super sensitivity of auxotrophic yeast mutants to the quaternary ammonium salts. The results of amino-acid transport into the auxotrophic yeast cells treated with a quaternary ammonium salt in the presence and absence of arginine are given. A working hypothesis of the mechanism of these salts action as a specific inhibition of nutrient transport is discussed. (author). 19 refs, 3 figs, 8 figs

Yeast cell wall chitin reduces wine haze formation.

Science.gov (United States)

Ndlovu, Thulile; Divol, Benoit; Bauer, Florian F

2018-04-27

Protein haze formation in bottled wines is a significant concern for the global wine industry and wine clarification before bottling is therefore a common but expensive practice. Previous studies have shown that wine yeast strains can reduce haze formation through the secretion of certain mannoproteins, but it has been suggested that other yeast-dependent haze protective mechanisms exist. On the other hand, addition of chitin has been shown to reduce haze formation, likely because grape chitinases have been shown to be the major contributors to haze. In this study, Chardonnay grape must fermented by various yeast strains resulted in wines with different protein haze levels indicating differences in haze protective capacities of the strains. The cell wall chitin levels of these strains were determined, and a strong correlation between cell wall chitin levels and haze protection capability was observed. To further evaluate the mechanism of haze protection, Escherichia coli -produced GFP-tagged grape chitinase was shown to bind efficiently to yeast cell walls in a cell wall chitin concentration-dependent manner, while commercial chitinase was removed from synthetic wine in quantities also correlated with the cell wall chitin levels of the strains. Our findings suggest a new mechanism of reducing wine haze, and propose a strategy for optimizing wine yeast strains to improve wine clarification. Importance In this study, we establish a new mechanism by which wine yeast strains can impact on the protein haze formation of wines, and demonstrate that yeast cell wall chitin binds grape chitinase in a chitin-concentration dependent manner. We also show that yeast can remove this haze-forming protein from wine. Chitin has in the past been shown to efficiently reduce wine haze formation when added to the wine in high concentration as a clarifying agent. Our data suggest that the selection of yeast strains with high levels of cell wall chitin can reduce protein haze. We also

Production of Food Grade Yeasts

Directory of Open Access Journals (Sweden)

Argyro Bekatorou

2006-01-01

Full Text Available Yeasts have been known to humans for thousands of years as they have been used in traditional fermentation processes like wine, beer and bread making. Today, yeasts are also used as alternative sources of high nutritional value proteins, enzymes and vitamins, and have numerous applications in the health food industry as food additives, conditioners and flavouring agents, for the production of microbiology media and extracts, as well as livestock feeds. Modern scientific advances allow the isolation, construction and industrial production of new yeast strains to satisfy the specific demands of the food industry. Types of commercial food grade yeasts, industrial production processes and raw materials are highlighted. Aspects of yeast metabolism, with respect to carbohydrate utilization, nutritional aspects and recent research advances are also discussed.

Reconstitution of the yeast RNA polymerase III transcription system with all recombinant factors.

Science.gov (United States)

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

2006-04-28

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

Immunogenicity and protective efficacy of yeast extracts containing rotavirus-like particles: a potential veterinary vaccine.

Science.gov (United States)

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

2014-05-19

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

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

Science.gov (United States)

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

2017-04-01

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

Yeast Acid Phosphatases and Phytases: Production, Characterization and Commercial Prospects

Science.gov (United States)

Kaur, Parvinder; Satyanarayana, T.

The element phosphorus is critical to all life forms as it forms the basic component of nucleic acids and ATP and has a number of indispensable biochemical roles. Unlike C or N, the biogeochemical cycling of phosphorus is very slow, and thus making it the growth-limiting element in most soils and aquatic systems. Phosphohydrolases (e.g. acid phosphatases and phytases) are enzymes that break the C-O-P ester bonds and provide available inorganic phosphorus from various inassimilable organic forms of phosphorus like phytates. These enzymes are of significant value in effectively combating phosphorus pollution. Although phytases and acid phosphatases are produced by various plants, animals and micro organisms, microbial sources are more promising for the production on a commercial scale. Yeasts being the simplest eukaryotes are ideal candidates for phytase and phos-phatase research due to their mostly non-pathogenic and GRAS status. They have not, however, been utilized to their full potential. This chapter focuses attention on the present state of knowledge on the production, characterization and potential commercial prospects of yeast phytases and acid phosphatases.

Dietary Yeast Cell Wall Extract Alters the Proteome of the Skin Mucous Barrier in Atlantic Salmon (Salmo salar: Increased Abundance and Expression of a Calreticulin-Like Protein.

Directory of Open Access Journals (Sweden)

Giulia Micallef

Full Text Available In order to improve fish health and reduce use of chemotherapeutants in aquaculture production, the immunomodulatory effect of various nutritional ingredients has been explored. In salmon, there is evidence that functional feeds can reduce the abundance of sea lice. This study aimed to determine if there were consistent changes in the skin mucus proteome that could serve as a biomarker for dietary yeast cell wall extract. The effect of dietary yeast cell wall extract on the skin mucus proteome of Atlantic salmon was examined using two-dimensional gel electrophoresis. Forty-nine spots showed a statistically significant change in their normalised volumes between the control and yeast cell wall diets. Thirteen spots were successfully identified by peptide fragment fingerprinting and LC-MS/MS and these belonged to a variety of functions and pathways. To assess the validity of the results from the proteome approach, the gene expression of a selection of these proteins was studied in skin mRNA from two different independent feeding trials using yeast cell wall extracts. A calreticulin-like protein increased in abundance at both the protein and transcript level in response to dietary yeast cell wall extract. The calreticulin-like protein was identified as a possible biomarker for yeast-derived functional feeds since it showed the most consistent change in expression in both the mucus proteome and skin transcriptome. The discovery of such a biomarker is expected to quicken the pace of research in the application of yeast cell wall extracts.

Yeast signaling pathways in the oxidative stress response

Energy Technology Data Exchange (ETDEWEB)

Ikner, Aminah [Section of Microbiology, Division of Biological Sciences, University of California, Davis, CA 95616 (United States); Shiozaki, Kazuhiro [Section of Microbiology, Division of Biological Sciences, University of California, Davis, CA 95616 (United States)]. E-mail: kshiozaki@ucdavis.edu

2005-01-06

Oxidative stress that generates the reactive oxygen species (ROS) is one of the major causes of DNA damage and mutations. The 'DNA damage checkpoint' that arrests cell cycle and repairs damaged DNA has been a focus of recent studies, and the genetically amenable model systems provided by yeasts have been playing a leading role in the eukaryotic checkpoint research. However, means to eliminate ROS are likely to be as important as the DNA repair mechanisms in order to suppress mutations in the chromosomal DNA, and yeasts also serve as excellent models to understand how eukaryotes combat oxidative stress. In this article, we present an overview of the signaling pathways that sense oxidative stress and induce expression of various anti-oxidant genes in the budding yeast Saccharomyces cerevisiae, the fission yeast Schizosaccharomyces pombe and the pathogenic yeast Candida albicans. Three conserved signaling modules have been identified in the oxidative stress response of these diverse yeast species: the stress-responsive MAP kinase cascade, the multistep phosphorelay and the AP-1-like transcription factor. The structure and function of these signaling modules are discussed.

Yeast signaling pathways in the oxidative stress response

International Nuclear Information System (INIS)

Ikner, Aminah; Shiozaki, Kazuhiro

2005-01-01

Oxidative stress that generates the reactive oxygen species (ROS) is one of the major causes of DNA damage and mutations. The 'DNA damage checkpoint' that arrests cell cycle and repairs damaged DNA has been a focus of recent studies, and the genetically amenable model systems provided by yeasts have been playing a leading role in the eukaryotic checkpoint research. However, means to eliminate ROS are likely to be as important as the DNA repair mechanisms in order to suppress mutations in the chromosomal DNA, and yeasts also serve as excellent models to understand how eukaryotes combat oxidative stress. In this article, we present an overview of the signaling pathways that sense oxidative stress and induce expression of various anti-oxidant genes in the budding yeast Saccharomyces cerevisiae, the fission yeast Schizosaccharomyces pombe and the pathogenic yeast Candida albicans. Three conserved signaling modules have been identified in the oxidative stress response of these diverse yeast species: the stress-responsive MAP kinase cascade, the multistep phosphorelay and the AP-1-like transcription factor. The structure and function of these signaling modules are discussed

Preparation and thermal properties of form stable paraffin phase change material encapsulation

International Nuclear Information System (INIS)

Liu Xing; Liu Hongyan; Wang Shujun; Zhang Lu; Cheng Hua

2006-01-01

Paraffin waxes are cheap and have moderate thermal energy storage density but low thermal conductivity and, hence, require large surface area to be used in energy storage. Form stable paraffin phase change materials (PCM) in which paraffin serves as a latent heat storage material and polyolefins act as a supporting material, because of paraffin leakage, are required to be improved. The form stable paraffin PCM in the present paper was encapsulated in an inorganic silica gel polymer successfully by in situ polymerization. The differential scanning calorimeter (DSC) was used to measure its thermal properties. At the same time, the Washburn equation, which measures the wetting properties of powder materials, was used to test the hydrophilic-lipophilic properties of the PCMs. The result indicated that the enthalpy of the microencapsulated PCMs was reduced little, while their hydrophilic properties were enhanced largely

Environmental assessment of different strategies for production of stabilized yeast

OpenAIRE

Monclus, Vincent; Pénicaud, Caroline; Perret, Bruno; Fonseca, Fernanda

2016-01-01

Yeast are widely used for producing fermented (bread, beer...) and health benefit (probiotics) products. The production of stable and active yeast involves fermentation, concentration, protection, drying (stabilization) and storage. During the stabilization and storage steps, the cells face numerous stress which may deteriorate functional properties and cause cell death. Different strategies can be used to preserve cell survival, such as changing growth medium for fermentation or adapting pro...

Crystal structure of the yeast nicotinamidase Pnc1p.

Science.gov (United States)

Hu, Gang; Taylor, Alexander B; McAlister-Henn, Lee; Hart, P John

2007-05-01

The yeast nicotinamidase Pnc1p acts in transcriptional silencing by reducing levels of nicotinamide, an inhibitor of the histone deacetylase Sir2p. The Pnc1p structure was determined at 2.9A resolution using MAD and MIRAS phasing methods after inadvertent crystallization during the pursuit of the structure of histidine-tagged yeast isocitrate dehydrogenase (IDH). Pnc1p displays a cluster of surface histidine residues likely responsible for its co-fractionation with IDH from Ni(2+)-coupled chromatography resins. Researchers expressing histidine-tagged proteins in yeast should be aware of the propensity of Pnc1p to crystallize, even when overwhelmed in concentration by the protein of interest. The protein assembles into extended helical arrays interwoven to form an unusually robust, yet porous superstructure. Comparison of the Pnc1p structure with those of three homologous bacterial proteins reveals a common core fold punctuated by amino acid insertions unique to each protein. These insertions mediate the self-interactions that define the distinct higher order oligomeric states attained by these molecules. Pnc1p also acts on pyrazinamide, a substrate analog converted by the nicotinamidase from Mycobacterium tuberculosis into a product toxic to that organism. However, we find no evidence for detrimental effects of the drug on yeast cell growth.

The retro-GCN4 leucine zipper sequence forms a stable three-dimensional structure

Science.gov (United States)

Mittl, Peer R. E.; Deillon, Christine; Sargent, David; Liu, Niankun; Klauser, Stephan; Thomas, Richard M.; Gutte, Bernd; Grütter, Markus G.

2000-01-01

The question of whether a protein whose natural sequence is inverted adopts a stable fold is still under debate. We have determined the 2.1-Å crystal structure of the retro-GCN4 leucine zipper. In contrast to the two-stranded helical coiled-coil GCN4 leucine zipper, the retro-leucine zipper formed a very stable, parallel four-helix bundle, which now lends itself to further structural and functional studies. PMID:10716989

Nitrile Metabolizing Yeasts

Science.gov (United States)

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

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

Activation of waste brewer's yeast Saccharomyces cerevisiae for bread production

Directory of Open Access Journals (Sweden)

Popov Stevan D.

2005-01-01

Full Text Available The waste brewer's yeast S. cerevisiae (activated and non-activated was compared with the commercial baker's yeast regarding the volume of developed gas in dough, volume and freshness stability of produced bread. The activation of waste brewer's yeast resulted in the increased volume of developed gas in dough by 100% compared to non-activated brewer's yeast, and the obtained bread is of more stable freshness compared to bread produced with baker's yeast. The activation of BY affects positively the quality of produced bread regarding bread volume. The volume of developed gas in dough prepared with the use of non-activated BY was not sufficient, therefore, it should not be used as fermentation agent, but only as an additive in bread production process for bread freshness preservation. Intense mixing of dough results in more compressible crumb 48 hrs after baking compared to high-speed mixing.

Yeast metabolic engineering--targeting sterol metabolism and terpenoid formation.

Science.gov (United States)

Wriessnegger, Tamara; Pichler, Harald

2013-07-01

Terpenoids comprise various structures conferring versatile functions to eukaryotes, for example in the form of prenyl-anchors they attach proteins to membranes. The physiology of eukaryotic membranes is fine-tuned by another terpenoid class, namely sterols. Evidence is accumulating that numerous membrane proteins require specific sterol structural features for function. Moreover, sterols are intermediates in the synthesis of steroids serving as hormones in higher eukaryotes. Like steroids many compounds of the terpenoid family do not contribute to membrane architecture, but serve as signalling, protective or attractant/repellent molecules. Particularly plants have developed a plenitude of terpenoid biosynthetic routes branching off early in the sterol biosynthesis pathway and, thereby, forming one of the largest groups of naturally occurring organic compounds. Many of these aromatic and volatile molecules are interesting for industrial application ranging from foods to pharmaceuticals. Combining the fortunate situation that sterol biosynthesis is highly conserved in eukaryotes with the amenability of yeasts to genetic and metabolic engineering, basically all naturally occurring terpenoids might be produced involving yeasts. Such engineered yeasts are useful for the study of biological functions and molecular interactions of terpenoids as well as for the large-scale production of high-value compounds, which are unavailable in sufficient amounts from natural sources due to their low abundance. Copyright © 2013 Elsevier Ltd. All rights reserved.

Yeast Colonies: A Model for Studies of Aging, Environmental Adaptation, and Longevity

Directory of Open Access Journals (Sweden)

Libuše Váchová

2012-01-01

Full Text Available When growing on solid surfaces, yeast, like other microorganisms, develops organized multicellular populations (colonies and biofilms that are composed of differentiated cells with specialized functions. Life within these populations is a prevalent form of microbial existence in natural settings that provides the cells with capabilities to effectively defend against environmental attacks as well as efficiently adapt and survive long periods of starvation and other stresses. Under such circumstances, the fate of an individual yeast cell is subordinated to the profit of the whole population. In the past decade, yeast colonies, with their complicated structure and high complexity that are also developed under laboratory conditions, have become an excellent model for studies of various basic cellular processes such as cell interaction, signaling, and differentiation. In this paper, we summarize current knowledge on the processes related to chronological aging, adaptation, and longevity of a colony cell population and of its differentiated cell constituents. These processes contribute to the colony ability to survive long periods of starvation and mostly differ from the survival strategies of individual yeast cells.

Random substitution of large parts of the propeptide of yeast proteinase A

DEFF Research Database (Denmark)

van den Hazel, H B; Kielland-Brandt, Morten; Winther, Jakob R.

1995-01-01

The yeast aspartic protease, proteinase A, has a 54 amino-acid propeptide, which is removed during activation of the zymogen in the vacuole. Apart from being involved inhibition/activation, the propeptide has been shown to be essential for formation of a stable active enzyme (van den Hazel, H. B...... of the mutants were subjected to a colony screen for ones exhibiting activity. A high frequency (around 1%) of active constructs was found, which indicates a very high tolerance for mutations in the propeptide. Thirty-nine functional mutant forms containing random sequence at either the N- or C-terminal half...

Stable tetrabenzo-Chichibabin's hydrocarbons: Tunable ground state and unusual transition between their closed-shell and open-shell resonance forms

KAUST Repository

Zeng, Zebing

2012-09-05

Stable open-shell polycyclic aromatic hydrocarbons (PAHs) are of fundamental interest due to their unique electronic, optical, and magnetic properties and promising applications in materials sciences. Chichibabin\\'s hydrocarbon as a classical open-shell PAH has been investigated for a long time. However, most of the studies are complicated by their inherent high reactivity. In this work, two new stable benzannulated Chichibabin\\'s hydrocarbons 1-CS and 2-OS were prepared, and their electronic structure and geometry in the ground state were studied by various experiments (steady-state and transient absorption spectra, NMR, electron spin resonance (ESR), superconducting quantum interference device (SQUID), FT Raman, X-ray crystallographic etc.) and density function theory (DFT) calculations. 1-CS and 2-OS exhibited tunable ground states, with a closed-shell quinoidal structure for 1-CS and an open-shell biradical form for 2-OS. Their corresponding excited-state forms 1-OS and 2-CS were also chemically approached and showed different decay processes. The biradical 1-OS displayed an unusually slow decay to the ground state (1-CS) due to a large energy barrier (95 ± 2.5 kJ/mol) arising from severe steric hindrance during the transition from an orthogonal biradical form to a butterfly-like quinoidal form. The quick transition from the quinoidal 2-CS (excited state) to the orthogonal biradicaloid 2-OS (ground state) happened during the attempted synthesis of 2-CS. Compounds 1-CS and 2-OS can be oxidized into stable dications by FeCl 3 and/or concentrated H 2SO 4. The open-shell 2-OS also exhibited a large two-photon absorption (TPA) cross section (760 GM at 1200 nm). © 2012 American Chemical Society.

Yeasts associated with fresh and frozen pulps of Brazilian tropical fruits.

Science.gov (United States)

Trindade, Rita C; Resende, Maria Aparecida; Silva, Claudia M; Rosa, Carlos A

2002-08-01

The occurrence of yeasts on ripe fruits and frozen pulps of pitanga (Eugenia uniflora L), mangaba (Hancornia speciosa Gom.), umbu (Spondias tuberosa Avr. Cam.), and acerola (Malpighia glaba L) was verified. The incidence of proteolytic, pectinolytic, and mycocinogenic yeasts on these communities was also determined. A total of 480 colonies was isolated and grouped in 405 different strains. These corresponded to 42 ascomycetous and 28 basidiomycetous species. Candida sorbosivorans, Pseudozyma antarctica, C. spandovensis-like, C. spandovensis, Kloeckera apis, C. parapsilosis, Rhodotorula graminis, Kluyveromyces marxianus, Cryptococcus laurentii, Metchnikowia sp (isolated only from pitanga ripe fruits), Issatchenkia occidentalis and C. krusei (isolated only from mangaba frozen pulps), were the most frequent species. The yeast communities from pitanga ripe fruits exhibited the highest frequency of species, followed by communities from acerola ripe fruits and mangaba frozen pulps. Yeast communities from frozen pulp and ripe fruits of umbu had the lowest number of species. Except the yeasts from pitanga, yeast communities from frozen pulp exhibited higher number of yeasts than ripe fruit communities. Mycocinogenic yeasts were found in all of the substrates studied except in communities from umbu ripe fruits and pitanga frozen pulps. Most of the yeasts found to produce mycocins were basidiomycetes and included P. antarctica, Cryptococcus albidus, C. bhutanensis-like, R. graminis and R. mucilaginosa-like from pitanga ripe fruits as well as black yeasts from pitanga and acerola ripe fruits. The umbu frozen pulps community had the highest frequency of proteolytic species. Yeasts able to hydrolyse casein at pH 5.0 represented 38.5% of the species isolated. Thirty-seven percent of yeast isolates were able to hydrolyse casein at pH 7.0. Pectinolytic yeasts were found in all of the communities studied, excepted for those of umbu frozen pulps. The highest frequency of

Incorporation of negative rules and evolution of a fuzzy controller for yeast fermentation process.

Science.gov (United States)

Birle, Stephan; Hussein, Mohamed Ahmed; Becker, Thomas

2016-08-01

The control of bioprocesses can be very challenging due to the fact that these kinds of processes are highly affected by various sources of uncertainty like the intrinsic behavior of the used microorganisms. Due to the reason that these kinds of process uncertainties are not directly measureable in most cases, the overall control is either done manually because of the experience of the operator or intelligent expert systems are applied, e.g., on the basis of fuzzy logic theory. In the latter case, however, the control concept is mainly represented by using merely positive rules, e.g., "If A then do B". As this is not straightforward with respect to the semantics of the human decision-making process that also includes negative experience in form of constraints or prohibitions, the incorporation of negative rules for process control based on fuzzy logic is emphasized. In this work, an approach of fuzzy logic control of the yeast propagation process based on a combination of positive and negative rules is presented. The process is guided along a reference trajectory for yeast cell concentration by alternating the process temperature. The incorporation of negative rules leads to a much more stable and accurate control of the process as the root mean squared error of reference trajectory and system response could be reduced by an average of 62.8 % compared to the controller using only positive rules.

Yeast Infection Test: MedlinePlus Lab Test Information

Science.gov (United States)

... cheese-like discharge Painful urination Redness in the vagina Yeast infection of the penis may cause: Redness Scaling Rash ... on the location of your symptoms: If a vaginal yeast infection is suspected , your health care provider will perform ...

Guidelines and recommendations on yeast cell death nomenclature

OpenAIRE

Carmona-Gutierrez, Didac; Bauer, Maria Anna; Zimmermann, Andreas; Aguilera, Andres; Austriaco, Nicanor; Sigrist, Stephan J.

2018-01-01

Elucidating the biology of yeast in its full complexity has major implications for science, medicine and industry. One of the most critical processes determining yeast life and physiology is cellular demise. However, the investigation of yeast cell death is a relatively young field, and a widely accepted set of concepts and terms is still missing. Here, we propose unified criteria for the definition of accidental, regulated, and programmed forms of cell death in yeast based on a series of mor...

Prion-based memory of heat stress in yeast.

Science.gov (United States)

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

2017-05-04

Amyloids and amyloid-based prions are self-perpetuating protein aggregates which can spread by converting a normal protein of the same sequence into a prion form. They are associated with diseases in humans and mammals, and control heritable traits in yeast and other fungi. Some amyloids are implicated in biologically beneficial processes. As prion formation generates reproducible memory of a conformational change, prions can be considered as molecular memory devices.  We have demonstrated that in yeast, stress-inducible cytoskeleton-associated protein Lsb2 forms a metastable prion in response to high temperature. This prion promotes conversion of other proteins into prions and can persist in a fraction of cells for a significant number of cell generations after stress, thus maintaining the memory of stress in a population of surviving cells. Acquisition of an amino acid substitution required for Lsb2 to form a prion coincides with acquisition of increased thermotolerance in the evolution of Saccharomyces yeast. Thus the ability to form an Lsb2 prion in response to stress coincides with yeast adaptation to growth at higher temperatures. These findings intimately connect prion formation to the cellular response to environmental stresses.

Yeasts and bacterial biosurfactants as demulsifiers for petroleum derivative in seawater emulsions.

Science.gov (United States)

Rocha E Silva, Fernanda Cristina P; Roque, Bruno Augusto C; Rocha E Silva, Nathalia Maria P; Rufino, Raquel D; Luna, Juliana M; Santos, Valdemir A; Banat, Ibrahim M; Sarubbo, Leonie A

2017-11-15

Oil sludge or waste generated in transport, storage or refining forms highly stable mixtures due to the presence and additives with surfactant properties and water forming complex emulsions. Thus, demulsification is necessary to separate this residual oil from the aqueous phase for oil processing and water treatment/disposal. Most used chemical demulsifiers, although effective, are environmental contaminants and do not meet the desired levels of biodegradation. We investigated the application of microbial biosurfactants as potential natural demulsifiers of petroleum derivatives in water emulsions. Biosurfactants crude extracts, produced by yeasts (Candida guilliermondii, Candida lipolytica and Candida sphaerica) and bacteria (Pseudomonas aeruginosa, Pseudomonas cepacia and Bacillus sp.) grown in industrial residues, were tested for demulsification capacity in their crude and pure forms. The best results obtained were for bacterial biosurfactants, which were able to recover about 65% of the seawater emulsified with motor oil compared to 35-40% only for yeasts products. Biosurfactants were also tested with oil-in-water (O/W) and water-in-oil (W/O) kerosene model emulsions. No relationship between interfacial tension, cell hydrophobicity and demulsification ratios was observed with all the biosurfactants tested. Microscopic illustrations of the emulsions in the presence of the biosurfactants showed the aspects of the emulsion and demulsification process. The results obtained demonstrate the potential of these agents as demulsifiers in marine environments.

Preparation and properties of lauric acid/silicon dioxide composites as form-stable phase change materials for thermal energy storage

International Nuclear Information System (INIS)

Fang Guiyin; Li Hui; Liu Xu

2010-01-01

Form-stable lauric acid (LA)/silicon dioxide (SiO 2 ) composite phase change materials were prepared using sol-gel methods. The LA was used as the phase change material for thermal energy storage, with the SiO 2 acting as the supporting material. The structural analysis of these form-stable LA/SiO 2 composite phase change materials was carried out using Fourier transformation infrared spectroscope (FT-IR). The microstructure of the form-stable composite phase change materials was observed by a scanning electronic microscope (SEM). The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetric analysis apparatus (TGA), respectively. The SEM results showed that the LA was well dispersed in the porous network of SiO 2 . The DSC results indicated that the melting latent heat of the form-stable composite phase change material is 117.21 kJ kg -1 when the mass percentage of the LA in the SiO 2 is 64.8%. The results of the TGA showed that these materials have good thermal stability. The form-stable composite phase change materials can be used for thermal energy storage in waste heat recovery and solar heating systems.

Cellobiose fermenting yeast produces varied forms of native ß-glucosidase

Science.gov (United States)

The rapid growing yeast strain NRRL Y-50464 is robust to environmental stress and resistant to 2-furaldehyde (furfural) and 5-[hydroxymethyl]-2-furaldehyde (HMF). It is able to utilize cellobiose as its sole source of carbon and produces ethanol from lignocellulosic biomass by simultaneous saccharif...

Game dynamic model for yeast development.

Science.gov (United States)

Huang, Yuanyuan; Wu, Zhijun

2012-07-01

Game theoretic models, along with replicator equations, have been applied successfully to the study of evolution of populations of competing species, including the growth of a population, the reaching of the population to an equilibrium state, and the evolutionary stability of the state. In this paper, we analyze a game model proposed by Gore et al. (Nature 456:253-256, 2009) in their recent study on the co-development of two mixed yeast strains. We examine the mathematical properties of this model with varying experimental parameters. We simulate the growths of the yeast strains and compare them with the experimental results. We also compute and analyze the equilibrium state of the system and prove that it is asymptotically and evolutionarily stable.

Polymorphic drugs examined with neutron spectroscopy: Is making more stable forms really that simple?

International Nuclear Information System (INIS)

Tsapatsaris, Nikolaos; Landsgesell, Sven; Koza, Michael M.; Frick, Bernhard; Boldyreva, Elena V.; Bordallo, Heloisa N.

2013-01-01

Highlights: • Pressure induced transition in the denser polymorphic form. • Weak strength of hydrogen bonds driving new stable packing. • Lattice anisotropy versus charge transfer. - Abstract: Understanding polymorphism in pharmaceutical ingredients is a long-standing challenge in formulation science. A well-known example is paracetamol, C 8 H 9 NO 2 . The marketed stable form I crystallizes with corrugated molecular layers. In contrast, form II, which is thermodynamically favorable at high pressures, has relatively planar layers that can slip over each other without difficulty, but is metastable at ambient conditions. By means of inelastic neutron scattering we demonstrated that the lattice modes of form II exhibit a sudden 1 meV energy shift at 300 K under a pressure of ca 0.4 GPa. Moreover, evidence of an increase of the vibrational energy in both polymorphs was found, which was accompanied, in form I, by an unexpectedly weak increase of the tunnel splitting. These results indicate an anisotropy of the potential surface probed by the methyl rotor, and are discussed in relation to the differences of the strength of the hydrogen bond environment for each polymorph

Polymorphic drugs examined with neutron spectroscopy: Is making more stable forms really that simple?

Energy Technology Data Exchange (ETDEWEB)

Tsapatsaris, Nikolaos [European Spallation Source ESS AB, P.O. Box 176, SE-221 00 Lund (Sweden); Landsgesell, Sven [Helmholtz Zentrum Berlin, Hahn-Meitner Platz, 1, 14109 Berlin (Germany); Koza, Michael M.; Frick, Bernhard [Institut Laue-Langevin, BP 156 38042, Grenoble Cedex 9 (France); Boldyreva, Elena V. [Novosibirsk State University, ul. Pirogova 2, Novosibirsk 630090 (Russian Federation); Institute of Solid State Chemistry and Mechanochemistry, ul. Kutateladze 18, Novosibirsk 630128 (Russian Federation); Bordallo, Heloisa N., E-mail: bordallo@nbi.ku.dk [Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen (Denmark)

2013-12-12

Highlights: • Pressure induced transition in the denser polymorphic form. • Weak strength of hydrogen bonds driving new stable packing. • Lattice anisotropy versus charge transfer. - Abstract: Understanding polymorphism in pharmaceutical ingredients is a long-standing challenge in formulation science. A well-known example is paracetamol, C{sub 8}H{sub 9}NO{sub 2}. The marketed stable form I crystallizes with corrugated molecular layers. In contrast, form II, which is thermodynamically favorable at high pressures, has relatively planar layers that can slip over each other without difficulty, but is metastable at ambient conditions. By means of inelastic neutron scattering we demonstrated that the lattice modes of form II exhibit a sudden 1 meV energy shift at 300 K under a pressure of ca 0.4 GPa. Moreover, evidence of an increase of the vibrational energy in both polymorphs was found, which was accompanied, in form I, by an unexpectedly weak increase of the tunnel splitting. These results indicate an anisotropy of the potential surface probed by the methyl rotor, and are discussed in relation to the differences of the strength of the hydrogen bond environment for each polymorph.

Identification of the Transcription Factor Znc1p, which Regulates the Yeast-to-Hypha Transition in the Dimorphic Yeast Yarrowia lipolytica

Science.gov (United States)

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

2013-01-01

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

C-Terminal Tyrosine Residue Modifications Modulate the Protective Phosphorylation of Serine 129 of α-Synuclein in a Yeast Model of Parkinson's Disease.

Science.gov (United States)

Kleinknecht, Alexandra; Popova, Blagovesta; Lázaro, Diana F; Pinho, Raquel; Valerius, Oliver; Outeiro, Tiago F; Braus, Gerhard H

2016-06-01

Parkinson´s disease (PD) is characterized by the presence of proteinaceous inclusions called Lewy bodies that are mainly composed of α-synuclein (αSyn). Elevated levels of oxidative or nitrative stresses have been implicated in αSyn related toxicity. Phosphorylation of αSyn on serine 129 (S129) modulates autophagic clearance of inclusions and is prominently found in Lewy bodies. The neighboring tyrosine residues Y125, Y133 and Y136 are phosphorylation and nitration sites. Using a yeast model of PD, we found that Y133 is required for protective S129 phosphorylation and for S129-independent proteasome clearance. αSyn can be nitrated and form stable covalent dimers originating from covalent crosslinking of two tyrosine residues. Nitrated tyrosine residues, but not di-tyrosine-crosslinked dimers, contributed to αSyn cytotoxicity and aggregation. Analysis of tyrosine residues involved in nitration and crosslinking revealed that the C-terminus, rather than the N-terminus of αSyn, is modified by nitration and di-tyrosine formation. The nitration level of wild-type αSyn was higher compared to that of A30P mutant that is non-toxic in yeast. A30P formed more dimers than wild-type αSyn, suggesting that dimer formation represents a cellular detoxification pathway in yeast. Deletion of the yeast flavohemoglobin gene YHB1 resulted in an increase of cellular nitrative stress and cytotoxicity leading to enhanced aggregation of A30P αSyn. Yhb1 protected yeast from A30P-induced mitochondrial fragmentation and peroxynitrite-induced nitrative stress. Strikingly, overexpression of neuroglobin, the human homolog of YHB1, protected against αSyn inclusion formation in mammalian cells. In total, our data suggest that C-terminal Y133 plays a major role in αSyn aggregate clearance by supporting the protective S129 phosphorylation for autophagy and by promoting proteasome clearance. C-terminal tyrosine nitration increases pathogenicity and can only be partially detoxified by �

Preparation and flammability of high density polyethylene/paraffin/organophilic montmorillonite hybrids as a form stable phase change material

International Nuclear Information System (INIS)

Cai, Yibing; Hu, Yuan; Song, Lei; Kong, Qinghong; Yang, Rui; Zhang, Yinping; Chen, Zuyao; Fan, Weicheng

2007-01-01

A kind of form stable phase change material (PCM) based on high density polyethylene (HDPE), paraffin, organophilic montmorillonite (OMT) and intumescent flame retardant (IFR) hybrids is prepared by using a twin screw extruder technique. This kind of form stable PCM is made of paraffin as a dispersed phase change material and HDPE as a supporting material. The structure of the montmorillonite (MMT) and OMT is characterized by X-ray diffraction (XRD) and high resolution electron microscopy (HREM). The analysis indicates that the MMT is a kind of lamellar structure, and the structure does not change after organic modification. However, the structure of the hybrid is evidenced by the XRD and scanning electronic microscope (SEM). Its thermal stability, latent heat and flame retardant properties are given by the Thermogravimetry analysis (TGA), differential scanning calorimeter (DSC) method and cone calorimeter, respectively. Synergy is observed between the OMT and IFR. The XRD result indicates that the paraffin intercalates into the silicate layers of the OMT, thus forming a typically intercalated hybrid. The SEM investigation and DSC result show that the additives of OMT and IFR have hardly any effect on the HDPE/paraffin three dimensional netted structure and the latent heat. In TGA curves, although the onset of weight loss of flame-retardant form stable PCMs occur at a lower temperature than that of form stable PCM, flame-retardant form stable PCMs produce a large amount of char residue at 700 o C. The synergy between OMT and IFR leads to the decrease of the heat release rate (HRR), contributing to improvement of the flammability performance

The relationship between salivary histatin levels and oral yeast carriage.

Science.gov (United States)

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

1998-06-01

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

Yeast lipids can phase separate into micrometer-scale membrane domains

DEFF Research Database (Denmark)

Klose, Christian; Ejsing, Christer S; Garcia-Saez, Ana J

2010-01-01

The lipid raft concept proposes that biological membranes have the potential to form functional domains based on a selective interaction between sphingolipids and sterols. These domains seem to be involved in signal transduction and vesicular sorting of proteins and lipids. Although there is bioc......The lipid raft concept proposes that biological membranes have the potential to form functional domains based on a selective interaction between sphingolipids and sterols. These domains seem to be involved in signal transduction and vesicular sorting of proteins and lipids. Although...... there is biochemical evidence for lipid raft-dependent protein and lipid sorting in the yeast Saccharomyces cerevisiae, direct evidence for an interaction between yeast sphingolipids and the yeast sterol ergosterol, resulting in membrane domain formation, is lacking. Here we show that model membranes formed from yeast...... total lipid extracts possess an inherent self-organization potential resulting in Ld-Lo phase coexistence at physiologically relevant temperature. Analyses of lipid extracts from mutants defective in sphingolipid metabolism as well as reconstitution of purified yeast lipids in model membranes of defined...

Yeast Colonies: A Model for Studies of Aging, Environmental Adaptation, and Longevity

OpenAIRE

Libuše Váchová; Michal Čáp; Zdena Palková

2012-01-01

When growing on solid surfaces, yeast, like other microorganisms, develops organized multicellular populations (colonies and biofilms) that are composed of differentiated cells with specialized functions. Life within these populations is a prevalent form of microbial existence in natural settings that provides the cells with capabilities to effectively defend against environmental attacks as well as efficiently adapt and survive long periods of starvation and other stresses. Under such circum...

Structural study of phosphomannan of yeast-form cells of Candida albicans J-1012 strain with special reference to application of mild acetolysis.

Science.gov (United States)

Kobayashi, H; Shibata, N; Mitobe, H; Ohkubo, Y; Suzuki, S

1989-08-01

Structural analysis of the phosphomannan isolated from yeast-form cells of a pathogenic yeast, Candida albicans J-1012 strain, was conducted. Treatment of this phosphomannan (Fr. J) with 10 mM HCl at 100 degrees C for 60 min gave a mixture of beta-1,2-linked manno-oligosaccharides, from tetraose to biose plus mannose, and an acid-stable mannan moiety (Fr. J-a), which was then acetolyzed by means of an acetolysis medium, 100:100:1 (v/v) mixture of (CH3CO)2O, CH3COOH, and H2SO4, at 40 degrees C for 36 h in order to avoid cleavage of the beta-1,2 linkage. The resultant manno-oligosaccharide mixture was fractionated on a column of Bio-Gel P-2 to yield insufficiently resolved manno-oligosaccharide fractions higher than pentaose and lower manno-oligosaccharides ranging from tetraose to biose plus mannose. The higher manno-oligosaccharide fraction was then digested with the Arthrobacter GJM-1 alpha-mannosidase in order to cleave the enzyme-susceptible alpha-1,2 and alpha-1,3 linkages, leaving manno-oligosaccharides containing the beta-1,2 linkage at their nonreducing terminal sites, Manp beta 1----2Manp alpha 1----2Manp alpha 1----2Manp alpha 1----2Man, Manp beta 1----2Manp beta 1----2Manp alpha 1----2Manp alpha 1---- 2Manp alpha 1----2Man, and Manp beta 1----2Manp beta 1----2Manp beta 1----2Manp alpha 1---- 2Manp alpha 1----2Manp alpha 1----2Man. However, the result of acetolysis of Fr. J-a by means of a 10:10:1 (v/v) mixture of (CH3CO)2O, CH3COOH, and H2SO4 at 40 degrees C for 13 h was significantly different from that obtained by the mild acetolysis method; i.e., the amount of mannose was apparently larger than that formed by the mild acetolysis method. In summary, a chemical structure for Fr. J as a highly branched mannan containing 14 different branching moieties was proposed.

Genomics and the making of yeast biodiversity.

Science.gov (United States)

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

2015-12-01

Yeasts are unicellular fungi that do not form fruiting bodies. Although the yeast lifestyle has evolved multiple times, most known species belong to the subphylum Saccharomycotina (syn. Hemiascomycota, hereafter yeasts). This diverse group includes the premier eukaryotic model system, Saccharomyces cerevisiae; the common human commensal and opportunistic pathogen, Candida albicans; and over 1000 other known species (with more continuing to be discovered). Yeasts are found in every biome and continent and are more genetically diverse than angiosperms or chordates. Ease of culture, simple life cycles, and small genomes (∼10-20Mbp) have made yeasts exceptional models for molecular genetics, biotechnology, and evolutionary genomics. Here we discuss recent developments in understanding the genomic underpinnings of the making of yeast biodiversity, comparing and contrasting natural and human-associated evolutionary processes. Only a tiny fraction of yeast biodiversity and metabolic capabilities has been tapped by industry and science. Expanding the taxonomic breadth of deep genomic investigations will further illuminate how genome function evolves to encode their diverse metabolisms and ecologies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Differential Proteome Analysis of a Flor Yeast Strain under Biofilm Formation.

Science.gov (United States)

Moreno-García, Jaime; Mauricio, Juan Carlos; Moreno, Juan; García-Martínez, Teresa

2017-03-28

Several Saccharomyces cerevisiae strains (flor yeasts) form a biofilm (flor velum) on the surface of Sherry wines after fermentation, when glucose is depleted. This flor velum is fundamental to biological aging of these particular wines. In this study, we identify abundant proteins in the formation of the biofilm of an industrial flor yeast strain. A database search to enrich flor yeast "biological process" and "cellular component" according to Gene Ontology Terminology (GO Terms) and, "pathways" was carried out. The most abundant proteins detected were largely involved in respiration, translation, stress damage prevention and repair, amino acid metabolism (glycine, isoleucine, leucine and arginine), glycolysis/gluconeogenesis and biosynthesis of vitamin B9 (folate). These proteins were located in cellular components as in the peroxisome, mitochondria, vacuole, cell wall and extracellular region; being these two last directly related with the flor formation. Proteins like Bgl2p, Gcv3p, Hyp2p, Mdh1p, Suc2p and Ygp1p were quantified in very high levels. This study reveals some expected processes and provides new and important information for the design of conditions and genetic constructions of flor yeasts for improving the cellular survival and, thus, to optimize biological aging of Sherry wine production.

An entropic form for NLFP with coulombic-like potential

International Nuclear Information System (INIS)

Grassi, A.

2012-01-01

Here it is proposed a new entropy form for which it is possible to obtain a stationary solution of the Non-Linear Fokker–Planck equation (NLFP) with coulombic-like potentials. The general properties of this new entropy form are shown and the results are compared with those obtained by other entropy forms. Finally, the behavior of the stationary solution in presence of two point charges is also shown. -- Highlights: ► In this Letter we have proposed a new form of entropy. ► Starting from this new entropy form a Non-Linear Fokker–Planck equation has been derived. ► The stationary solution of the Non-Linear Fokker–Planck equation is obtained by using an external coulombic-like potential. ► A comparison with other forms of entropies has been proposed in the case of a single or two point charges.

Different characteristics between menadione and menadione sodium bisulfite as redox mediator in yeast cell suspension

OpenAIRE

Yamashoji, Shiro

2016-01-01

Menadione promoted the production of active oxygen species (AOS) in both yeast cell suspension and the crude enzymes from the cells, but menadione sodium bisulfite (MSB) had little effect on the production of AOS in the cell suspension. MSB kept the stable increase in the electron transfer from intact yeast cells to anode compared to menadione, but the electron transfer promoted by MSB was inhibited in permeabilized yeast cell suspension. Menadione promoted oxidation of NAD(P)H much faster th...

ATP-binding motifs play key roles in Krp1p, kinesin-related protein 1, function for bi-polar growth control in fission yeast

International Nuclear Information System (INIS)

Rhee, Dong Keun; Cho, Bon A; Kim, Hyong Bai

2005-01-01

Kinesin is a microtubule-based motor protein with various functions related to the cell growth and division. It has been reported that Krp1p, kinesin-related protein 1, which belongs to the kinesin heavy chain superfamily, localizes on microtubules and may play an important role in cytokinesis. However, the function of Krp1p has not been fully elucidated. In this study, we overexpressed an intact form and three different mutant forms of Krp1p in fission yeast constructed by site-directed mutagenesis in two ATP-binding motifs or by truncation of the leucine zipper-like motif (LZiP). We observed hyper-extended microtubules and the aberrant nuclear shape in Krp1p-overexpressed fission yeast. As a functional consequence, a point mutation of ATP-binding domain 1 (G89E) in Krp1p reversed the effect of Krp1p overexpression in fission yeast, whereas the specific mutation in ATP-binding domain 2 (G238E) resulted in the altered cell polarity. Additionally, truncation of the leucine zipper-like domain (LZiP) at the C-terminal of Krp1p showed a normal nuclear division. Taken together, we suggest that krp1p is involved in regulation of cell-polarized growth through ATP-binding motifs in fission yeast

Characterization of culturable yeast species associating with whole crop corn and total mixed ration silage.

Science.gov (United States)

Wang, Huili; Hao, Wei; Ning, Tingting; Zheng, Mingli; Xu, Chuncheng

2018-02-01

This study investigated the association of yeast species with improved aerobic stability of total mixed ration (TMR) silages with prolonged ensiling, and clarified the characteristics of yeast species and their role during aerobic deterioration. Whole crop corn (WCC) silages and TMR silages formulated with WCC were ensiled for 7, 14, 28, and 56 d and used for an aerobic stability test. Predominant yeast species were isolated from different periods and identified by sequencing analyses of the 26S rRNA gene D1/D2 domain. Characteristics (assimilation and tolerance) of the yeast species and their role during aerobic deterioration were investigated. In addition to species of Candida glabrata and Pichia kudriavzevii ( P. kudriavzevii ) previously isolated in WCC and TMR, Pichia manshurica ( P. manshurica ), Candida ethanolica ( C. ethanolica ), and Zygosaccharomyces bailii ( Z. bailii ) isolated at great frequency during deterioration, were capable of assimilating lactic or acetic acid and tolerant to acetic acid and might function more in deteriorating TMR silages at early fermentation (7 d and 14 d). With ensiling prolonged to 28 d, silages became more (p<0.01) stable when exposed to air, coinciding with the inhibition of yeast to below the detection limit. Species of P. manshurica that were predominant in deteriorating WCC silages were not detectable in TMR silages. In addition, the predominant yeast species of Z. bailii in deteriorating TMR silages at later fermentation (28 d and 56 d) were not observed in both WCC and WCC silages. The inhibition of yeasts, particularly P. kudriavzevii , probably account for the improved aerobic stability of TMR silages at later fermentation. Fewer species seemed to be involved in aerobic deterioration of silages at later fermentation and Z. bailii was most likely to initiate the aerobic deterioration of TMR silages at later fermentation. The use of WCC in TMR might not influence the predominant yeast species during aerobic

Characterization of culturable yeast species associating with whole crop corn and total mixed ration silage

Directory of Open Access Journals (Sweden)

Huili Wang

2018-02-01

Full Text Available Objective This study investigated the association of yeast species with improved aerobic stability of total mixed ration (TMR silages with prolonged ensiling, and clarified the characteristics of yeast species and their role during aerobic deterioration. Methods Whole crop corn (WCC silages and TMR silages formulated with WCC were ensiled for 7, 14, 28, and 56 d and used for an aerobic stability test. Predominant yeast species were isolated from different periods and identified by sequencing analyses of the 26S rRNA gene D1/D2 domain. Characteristics (assimilation and tolerance of the yeast species and their role during aerobic deterioration were investigated. Results In addition to species of Candida glabrata and Pichia kudriavzevii (P. kudriavzevii previously isolated in WCC and TMR, Pichia manshurica (P. manshurica, Candida ethanolica (C. ethanolica, and Zygosaccharomyces bailii (Z. bailii isolated at great frequency during deterioration, were capable of assimilating lactic or acetic acid and tolerant to acetic acid and might function more in deteriorating TMR silages at early fermentation (7 d and 14 d. With ensiling prolonged to 28 d, silages became more (p<0.01 stable when exposed to air, coinciding with the inhibition of yeast to below the detection limit. Species of P. manshurica that were predominant in deteriorating WCC silages were not detectable in TMR silages. In addition, the predominant yeast species of Z. bailii in deteriorating TMR silages at later fermentation (28 d and 56 d were not observed in both WCC and WCC silages. Conclusion The inhibition of yeasts, particularly P. kudriavzevii, probably account for the improved aerobic stability of TMR silages at later fermentation. Fewer species seemed to be involved in aerobic deterioration of silages at later fermentation and Z. bailii was most likely to initiate the aerobic deterioration of TMR silages at later fermentation. The use of WCC in TMR might not influence the predominant

Toward low-cost affinity reagents: lyophilized yeast-scFv probes specific for pathogen antigens.

Directory of Open Access Journals (Sweden)

Sean A Gray

Full Text Available The generation of affinity reagents, usually monoclonal antibodies, remains a critical bottleneck in biomedical research and diagnostic test development. Recombinant antibody-like proteins such as scFv have yet to replace traditional monoclonal antibodies in antigen detection applications, in large part because of poor performance of scFv in solution. To address this limitation, we have developed assays that use whole yeast cells expressing scFv on their surfaces (yeast-scFv in place of soluble purified scFv or traditional monoclonal antibodies. In this study, a nonimmune library of human scFv displayed on the surfaces of yeast cells was screened for clones that bind to recombinant cyst proteins of Entamoeba histolytica, an enteric pathogen of humans. Selected yeast-scFv clones were stabilized by lyophilization and used in detection assay formats in which the yeast-scFv served as solid support-bound monoclonal antibodies. Specific binding of antigen to the yeast-scFv was detected by staining with rabbit polyclonal antibodies. In flow cytometry-based assays, lyophilized yeast-scFv reagents retained full binding activity and specificity for their cognate antigens after 4 weeks of storage at room temperature in the absence of desiccants or stabilizers. Because flow cytometry is not available to all potential assay users, an immunofluorescence assay was also developed that detects antigen with similar sensitivity and specificity. Antigen-specific whole-cell yeast-scFv reagents can be selected from nonimmune libraries in 2-3 weeks, produced in vast quantities, and packaged in lyophilized form for extended shelf life. Lyophilized yeast-scFv show promise as low cost, renewable alternatives to monoclonal antibodies for diagnosis and research.

Virus-like particle production with yeast: ultrastructural and immunocytochemical insights into Pichia pastoris producing high levels of the Hepatitis B surface antigen

Directory of Open Access Journals (Sweden)

Adnan Ahmad

2011-06-01

Full Text Available Abstract Background A protective immune response against Hepatitis B infection can be obtained through the administration of a single viral polypeptide, the Hepatitis B surface antigen (HBsAg. Thus, the Hepatitis B vaccine is generated through the utilization of recombinant DNA technology, preferentially by using yeast-based expression systems. However, the polypeptide needs to assemble into spherical particles, so-called virus-like particles (VLPs, to elicit the required protective immune response. So far, no clear evidence has been presented showing whether HBsAg assembles in vivo inside the yeast cell into VLPs or later in vitro during down-stream processing and purification. Results High level production of HBsAg was carried out with recombinant Pichia pastoris using the methanol inducible AOX1 expression system. The recombinant vaccine was isolated in form of VLPs after several down-stream steps from detergent-treated cell lysates. Search for the intracellular localization of the antigen using electron microscopic studies in combination with immunogold labeling revealed the presence of HBsAg in an extended endoplasmic reticulum where it was found to assemble into defined multi-layered, lamellar structures. The distance between two layers was determined as ~6 nm indicating that these lamellas represent monolayers of well-ordered HBsAg subunits. We did not find any evidence for the presence of VLPs within the endoplasmic reticulum or other parts of the yeast cell. Conclusions It is concluded that high level production and intrinsic slow HBsAg VLP assembly kinetics are leading to retention and accumulation of the antigen in the endoplasmic reticulum where it assembles at least partly into defined lamellar structures. Further transport of HBsAg to the Golgi apparatus is impaired thus leading to secretory pathway disfunction and the formation of an extended endoplasmic reticulum which bulges into irregular cloud-shaped formations. As VLPs were

The ribosome-associated complex antagonizes prion formation in yeast.

Science.gov (United States)

Amor, Alvaro J; Castanzo, Dominic T; Delany, Sean P; Selechnik, Daniel M; van Ooy, Alex; Cameron, Dale M

2015-01-01

The number of known fungal proteins capable of switching between alternative stable conformations is steadily increasing, suggesting that a prion-like mechanism may be broadly utilized as a means to propagate altered cellular states. To gain insight into the mechanisms by which cells regulate prion formation and toxicity we examined the role of the yeast ribosome-associated complex (RAC) in modulating both the formation of the [PSI(+)] prion - an alternative conformer of Sup35 protein - and the toxicity of aggregation-prone polypeptides. The Hsp40 RAC chaperone Zuo1 anchors the RAC to ribosomes and stimulates the ATPase activity of the Hsp70 chaperone Ssb. We found that cells lacking Zuo1 are sensitive to over-expression of some aggregation-prone proteins, including the Sup35 prion domain, suggesting that co-translational protein misfolding increases in Δzuo1 strains. Consistent with this finding, Δzuo1 cells exhibit higher frequencies of spontaneous and induced prion formation. Cells expressing mutant forms of Zuo1 lacking either a C-terminal charged region required for ribosome association, or the J-domain responsible for Ssb ATPase stimulation, exhibit similarly high frequencies of prion formation. Our findings are consistent with a role for the RAC in chaperoning nascent Sup35 to regulate folding of the N-terminal prion domain as it emerges from the ribosome.

Mammalian amyloidogenic proteins promote prion nucleation in yeast.

Science.gov (United States)

Chandramowlishwaran, Pavithra; Sun, Meng; Casey, Kristin L; Romanyuk, Andrey V; Grizel, Anastasiya V; Sopova, Julia V; Rubel, Aleksandr A; Nussbaum-Krammer, Carmen; Vorberg, Ina M; Chernoff, Yury O

2018-03-02

Fibrous cross-β aggregates (amyloids) and their transmissible forms (prions) cause diseases in mammals (including humans) and control heritable traits in yeast. Initial nucleation of a yeast prion by transiently overproduced prion-forming protein or its (typically, QN-rich) prion domain is efficient only in the presence of another aggregated (in most cases, QN-rich) protein. Here, we demonstrate that a fusion of the prion domain of yeast protein Sup35 to some non-QN-rich mammalian proteins, associated with amyloid diseases, promotes nucleation of Sup35 prions in the absence of pre-existing aggregates. In contrast, both a fusion of the Sup35 prion domain to a multimeric non-amyloidogenic protein and the expression of a mammalian amyloidogenic protein that is not fused to the Sup35 prion domain failed to promote prion nucleation, further indicating that physical linkage of a mammalian amyloidogenic protein to the prion domain of a yeast protein is required for the nucleation of a yeast prion. Biochemical and cytological approaches confirmed the nucleation of protein aggregates in the yeast cell. Sequence alterations antagonizing or enhancing amyloidogenicity of human amyloid-β (associated with Alzheimer's disease) and mouse prion protein (associated with prion diseases), respectively, antagonized or enhanced nucleation of a yeast prion by these proteins. The yeast-based prion nucleation assay, developed in our work, can be employed for mutational dissection of amyloidogenic proteins. We anticipate that it will aid in the identification of chemicals that influence initial amyloid nucleation and in searching for new amyloidogenic proteins in a variety of proteomes. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Stable and rigid DTPA-like paramagnetic tags suitable for in vitro and in situ protein NMR analysis.

Science.gov (United States)

Chen, Jia-Liang; Zhao, Yu; Gong, Yan-Jun; Pan, Bin-Bin; Wang, Xiao; Su, Xun-Cheng

2018-02-01

Organic synthesis of a ligand with high binding affinities for paramagnetic lanthanide ions is an effective way of generating paramagnetic effects on proteins. These paramagnetic effects manifested in high-resolution NMR spectroscopy are valuable dynamic and structural restraints of proteins and protein-ligand complexes. A paramagnetic tag generally contains a metal chelating moiety and a reactive group for protein modification. Herein we report two new DTPA-like tags, 4PS-PyDTTA and 4PS-6M-PyDTTA that can be site-specifically attached to a protein with a stable thioether bond. Both protein-tag adducts form stable lanthanide complexes, of which the binding affinities and paramagnetic tensors are tunable with respect to the 6-methyl group in pyridine. Paramagnetic relaxation enhancement (PRE) effects of Gd(III) complex on protein-tag adducts were evaluated in comparison with pseudocontact shift (PCS), and the results indicated that both 4PS-PyDTTA and 4PS-6M-PyDTTA tags are rigid and present high-quality PREs that are crucially important in elucidation of the dynamics and interactions of proteins and protein-ligand complexes. We also show that these two tags are suitable for in-situ protein NMR analysis.

Enhanced mitochondrial degradation of yeast cytochrome c with amphipathic structures.

Science.gov (United States)

Chen, Xi; Moerschell, Richard P; Pearce, David A; Ramanan, Durga D; Sherman, Fred

2005-02-01

The dispensable N-terminus of iso-1-cytochrome c (iso-1) in the yeast Saccharomyces cerevisiae was replaced by 11 different amphipathic structures. Rapid degradation of the corresponding iso-1 occurred, with the degree of degradation increasing with the amphipathic moments; and this amphipathic-dependent degradation was designated ADD. ADD occurred with the holo-forms in the mitochondria but not as the apo-forms in the cytosol. The extreme mutant type degraded with a half-life of approximately 12 min, whereas the normal iso-1 was stable over hours. ADD was influenced by the rho+/rho- state and by numerous chromosomal genes. Most importantly, ADD appeared to be specifically suppressed to various extents by deletions of any of the YME1, AFG3, or RCA1 genes encoding membrane-associated mitochondrial proteases, probably because the amphipathic structures caused a stronger association with the mitochondrial inner membrane and its associated proteases. The use of ADD assisted in the differentiation of substrates of different mitochondrial degradation pathways.

Preparation, characterization and thermal properties of styrene maleic anhydride copolymer (SMA)/fatty acid composites as form stable phase change materials

International Nuclear Information System (INIS)

Sari, Ahmet; Alkan, Cemil; Karaipekli, Ali; Onal, Adem

2008-01-01

Fatty acids such as stearic acid (SA), palmitic acid (PA), myristic acid (MA) and lauric acid (LA) are promising phase change materials (PCMs) for latent heat thermal energy storage (LHTES) applications, but high cost is the major drawback of them, limiting their utility area in thermal energy storage. The use of fatty acids as form stable PCMs will increase their feasibilities in practical applications due to the reduced cost of the LHTES system. In this regard, a series of styrene maleic anhydride copolymer (SMA)/fatty acid composites, SMA/SA, SMA/PA, SMA/MA, and SMA/LA, were prepared as form stable PCMs by encapsulation of fatty acids into the SMA, which acts as a supporting material. The encapsulation ratio of fatty acids was as much as 85 wt.% and no leakage of fatty acid was observed even when the temperature of the form stable PCM was over the melting point of the fatty acid in the composite. The prepared form stable composite PCMs were characterized using optic microscopy (OM), viscosimetry and Fourier transform infrared (FT-IR) spectroscopy methods, and the results showed that the SMA was physically and chemically compatible with the fatty acids. In addition, the thermal characteristics such as melting and freezing temperatures and latent heats of the form stable composite PCMs were measured by using the differential scanning calorimetry (DSC) technique, which indicated they had good thermal properties. On the basis of all the results, it was concluded that form stable SMA/fatty acid composite PCMs had important potential for practical LHTES applications such as under floor space heating of buildings and passive solar space heating of buildings by using wallboard, plasterboard or floors impregnated with a form stable PCM due to their satisfying thermal properties, easy preparation in desired dimensions, direct usability without needing additional encapsulation thereby eliminating the thermal resistance caused by the shell and, thus, reducing the cost of

Stable panoramic views facilitate snap-shot like memories for spatial reorientation in homing pigeons.

Directory of Open Access Journals (Sweden)

Tommaso Pecchia

Full Text Available Following spatial disorientation, animals can reorient themselves by relying on geometric cues (metric and sense specified both by the macroscopic surface layout of an enclosed space and prominent visual landmarks in arrays. Whether spatial reorientation in arrays of landmarks is based on explicit representation of the geometric cues is a matter of debate. Here we trained homing pigeons (Columba livia to locate a food-reward in a rectangular array of four identical or differently coloured pipes provided with four openings, only one of which allowed the birds to have access to the reward. Pigeons were trained either with a stable or a variable position of the opening on pipes, so that they could view the array either from the same or a variable perspective. Explicit mapping of configural geometry would predict successful reorientation irrespective of access condition. In contrast, we found that a stable view of the array facilitated spatial learning in homing pigeons, likely through the formation of snapshot-like memories.

Physicochemical characterization and sensory analysis of yeast-leavened and sourdough soy breads.

Science.gov (United States)

Yezbick, Gabrielle; Ahn-Jarvis, Jennifer; Schwartz, Steven J; Vodovotz, Yael

2013-10-01

Sourdough fermentation has been shown to have numerous beneficial effects on bread quality, and nutritionally enhance soy-supplemented bread by altering isoflavone chemical forms. Given this, the objective of this study was to compare the loaf quality and shelf life of sourdough and yeast-leavened soy breads by various physical, thermal, and sensorial methods, and to assess the effects of fermentation by various microorganisms on isoflavone profile in dough and breads using high-performance liquid chromatography analysis. Sourdough fermentation yielded a less extensible dough compared to yeast-leavened soy dough (P bread crumb (P yeast-leavened soy bread (Y-B). Sensory analysis revealed a significantly higher overall liking of Y-B compared to sourdough soy bread (SD-B) (P bread consumption frequency may be determinants of Y-B or SD-B preference. SD-B and Y-B exhibited similar shelf-life properties. Despite significantly different enthalpies associated with the melting of amylose-lipid complexes, thermal analysis of the 2 soy breads stored for 10 d (ambient conditions) demonstrated no significant difference in water distribution and starch retrogradation (P < 0.05). Lastly, SD-B was determined to have 32% of total isoflavones occurring in the aglycone form compared to 17% in Y-B. These findings warrant further investigation of sourdough fermentation as a processing technique for quality and nutritional enhancement of soy-based baked goods. © 2013 Institute of Food Technologists®

Therapeutic activity of a Saccharomyces cerevisiae-based probiotic and inactivated whole yeast on vaginal candidiasis.

Science.gov (United States)

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

2017-01-02

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

PEG/SiO2–Al2O3 hybrid form-stable phase change materials with enhanced thermal conductivity

International Nuclear Information System (INIS)

Tang, Bingtao; Wu, Cheng; Qiu, Meige; Zhang, Xiwen; Zhang, Shufen

2014-01-01

The thermal conductivity of form-stable PEG/SiO 2 phase change material (PCM) was enhanced by in situ doping of Al 2 O 3 using an ultrasound-assisted sol–gel method. Fourier transform infrared spectroscopy (FT-IR) was used to characterize the structure, and the crystal performance was characterized by the X-ray diffraction (XRD). Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) were used to determine the thermal properties. The phase change enthalpy of PEG/SiO 2 –Al 2 O 3 reached 124 J g −1 , and thermal conductivity improved by 12.8% for 3.3 wt% Al 2 O 3 in the PCM compared with PEG/SiO 2 . The hybrid PCM has excellent thermal stability and form-stable effects. - Highlights: • The PEG/SiO 2 –Al 2 O 3 hybrid form-stable phase change material (PCM) was obtained through the sol–gel method. • The inexpensive aluminum nitrate and tetraethyl orthosilicate were used as sol precursors. • This organic–inorganic hybrid process can effectively enhance the thermal conductivity of PCMs. • The PCM exhibited high thermal stability and excellent form-stable effects

Isolation and Characterization of melanized yeast form of Aureobasidium pullulans and physiological studies on the melanization process

International Nuclear Information System (INIS)

El-Gamal, M.S.; El-Bialy, H.A.; Elsayed, M.A.; Khalifa, M.A.

2017-01-01

Melanin pigments have immense application potentials in the fields of agriculture , cosmetics and pharmaceutical industries . Isolation and characterization of melanin producer from local resources is the main aim of the present study . Six melanized yeast isolates were selected from seventeen isolation resources including natural sources (Eucalyptus globules plant), industrial wastes (Tomato paste processing) and surface contaminants (Bathrooms). The selected yeasts were screened for melanin production in an individual experiment , results revealed the ability of yeast isolate selected from wastes of tomato paste processing (W 3 ) to produce melanin at 300 mM concentration . The selected melanized yeast was identified as Aureobasidium pullulans according to the morphological characteristics and 18S rRNA . Melanin production by the selected yeast was maximized by optimization of the cultural conditions and nutritional parameters by nearly two folds ( 550 mM ). The highest melanin yield was achieved in the fermentation medium contains 30 gl -1 sucrose , 35 gl -1 peptone and 1 mM L - DOPA concentration after nine days of incubation at 30°C and its pH value is adjusted at 7.0. Melanin characterization by FTIR and NMR resemble aliphatic and aromatic composition of A . pullulans ’ s melanin . In conclusion, the selected yeast is a promising candidate for melanin production in a semipilot scale

Oxidative Stress and Programmed Cell Death in Yeast

International Nuclear Information System (INIS)

Farrugia, Gianluca; Balzan, Rena

2012-01-01

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

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

DEFF Research Database (Denmark)

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...

Breeding research on sake yeasts in Japan: history, recent technological advances, and future perspectives.

Science.gov (United States)

Kitagaki, Hiroshi; Kitamoto, Katsuhiko

2013-01-01

Sake is an alcoholic beverage of Japan, with a tradition lasting more than 1,300 years; it is produced from rice and water by fermenting with the koji mold Aspergillus oryzae and sake yeast Saccharomyces cerevisiae. Breeding research on sake yeasts was originally developed in Japan by incorporating microbiological and genetic research methodologies adopted in other scientific areas. Since the advent of a genetic paradigm, isolation of yeast mutants has been a dominant approach for the breeding of favorable sake yeasts. These sake yeasts include (a) those that do not form foams (produced by isolating a mutant that does not stick to foams, thus decreasing the cost of sake production); (b) those that do not produce urea, which leads to the formation of ethyl carbamate, a possible carcinogen (isolated by positive selection in a canavanine-, arginine-, and ornithine-containing medium); (c) those that produce an increased amount of ethyl caproate, an apple-like flavor (produced by isolating a mutant resistant to cerulenin, an inhibitor of fatty-acid synthesis); and (d) those that produce a decreased amount of pyruvate (produced by isolating a mutant resistant to an inhibitor of mitochondrial transport, thus decreasing the amount of diacetyl). Given that sake yeasts perform sexual reproduction, sporulation and mating are potent approaches for their breeding. Recently, the genome sequences of sake yeasts have been determined and made publicly accessible. By utilizing this information, the quantitative trait loci (QTLs) for the brewing characteristics of sake yeasts have been identified, which paves a way to DNA marker-assisted selection of the mated strains. Genetic engineering technologies for experimental yeast strains have recently been established by academic groups, and these technologies have also been applied to the breeding of sake yeasts. Sake yeasts whose genomes have been modified with these technologies correspond to genetically modified organisms (GMOs

r-es-onance

Indian Academy of Sciences (India)

of extra-terrestrial life possible. However, ... likely place for a stable life form to arise and to flourish; and ... The hot liquid is then cooled and yeast added to it. ... the liquid. Because the liquid appears to be boiling this bubbling process is called.

ODE, RDE and SDE models of cell cycle dynamics and clustering in yeast.

Science.gov (United States)

Boczko, Erik M; Gedeon, Tomas; Stowers, Chris C; Young, Todd R

2010-07-01

Biologists have long observed periodic-like oxygen consumption oscillations in yeast populations under certain conditions, and several unsatisfactory explanations for this phenomenon have been proposed. These ‘autonomous oscillations’ have often appeared with periods that are nearly integer divisors of the calculated doubling time of the culture. We hypothesize that these oscillations could be caused by a form of cell cycle synchronization that we call clustering. We develop some novel ordinary differential equation models of the cell cycle. For these models, and for random and stochastic perturbations, we give both rigorous proofs and simulations showing that both positive and negative growth rate feedback within the cell cycle are possible agents that can cause clustering of populations within the cell cycle. It occurs for a variety of models and for a broad selection of parameter values. These results suggest that the clustering phenomenon is robust and is likely to be observed in nature. Since there are necessarily an integer number of clusters, clustering would lead to periodic-like behaviour with periods that are nearly integer divisors of the period of the cell cycle. Related experiments have shown conclusively that cell cycle clustering occurs in some oscillating yeast cultures.

The Absence of a Mature Cell Wall Sacculus in Stable Listeria monocytogenes L-Form Cells Is Independent of Peptidoglycan Synthesis.

Science.gov (United States)

Studer, Patrick; Borisova, Marina; Schneider, Alexander; Ayala, Juan A; Mayer, Christoph; Schuppler, Markus; Loessner, Martin J; Briers, Yves

2016-01-01

L-forms are cell wall-deficient variants of otherwise walled bacteria that maintain the ability to survive and proliferate in absence of the surrounding peptidoglycan sacculus. While transient or unstable L-forms can revert to the walled state and may still rely on residual peptidoglycan synthesis for multiplication, stable L-forms cannot revert to the walled form and are believed to propagate in the complete absence of peptidoglycan. L-forms are increasingly studied as a fundamental biological model system for cell wall synthesis. Here, we show that a stable L-form of the intracellular pathogen Listeria monocytogenes features a surprisingly intact peptidoglycan synthesis pathway including glycosyl transfer, in spite of the accumulation of multiple mutations during prolonged passage in the cell wall-deficient state. Microscopic and biochemical analysis revealed the presence of peptidoglycan precursors and functional glycosyl transferases, resulting in the formation of peptidoglycan polymers but without the synthesis of a mature cell wall sacculus. In conclusion, we found that stable, non-reverting L-forms, which do not require active PG synthesis for proliferation, may still continue to produce aberrant peptidoglycan.

Occurrence and function of yeasts in Asian indigenous fermented foods

NARCIS (Netherlands)

Aidoo, K.E.; Nout, M.J.R.; Sarkar, P.K.

2006-01-01

In the Asian region, indigenous fermented foods are important in daily life. In many of these foods, yeasts are predominant and functional during the fermentation. The diversity of foods in which yeasts predominate ranges from leavened bread-like products such as nan and idli, to alcoholic beverages

The carbon consumption pattern of the spoilage yeast Brettanomyces bruxellensis in synthetic wine-like medium.

Science.gov (United States)

Smith, Brendan D; Divol, Benoit

2018-08-01

The wine matrix contains limited carbon compounds to sustain microbial life. Brettanomyces bruxellensis is one of very few yeast species that has adapted to this environment. Indeed, the presence of growth-inhibiting compounds and conditions do not prevent its proliferation. Literature regarding the nutritional requirements of this yeast is surprisingly poor, given the observation that B. bruxellensis produces biomass with apparently less nutrients than other yeasts. In this study, various carbon sources were screened in a synthetic wine medium, under anaerobic and semi-aerobic growth conditions, in order to determine which compounds B. bruxellensis assimilates. Slight differences were observed between strains but overall, B. bruxellensis produced biomass from limited nutrients consumed in a specific order regardless of the oxygen conditions. Upon initial consumption of the simple sugars, B. bruxellensis was able to remain viable, by concurrently utilising ethanol (only in the presence of oxygen) and malic acid. Although initially beneficial, oxygen was found detrimental in the long term. Formation of volatile phenols occurred during the consumption of the sugars but not as a mechanism to help correct the redox imbalance. The study confirms that B. bruxellensis is able to survive using limited amount of nutrients, making this yeast a challenge for winemakers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Screening of high-yield GTF yeast by N+-implantation

International Nuclear Information System (INIS)

Gao Yanhong; Lv Jiaping; Liu Lu; Li Shurong

2009-01-01

In this study, one of the highest chromium-resistant strain was screened from 12 tested brewer's yeast. N + ion implantation was used to mutate this yeast and screened high-yield GTF yeast strains with Chromium tolerance method. The mutagenesis was conducted by 50 KeV N + ion implantation with the doses of 1 x 2.6 x 10 13 , 2 x 2.6 x 10 13 , 3 x 2.6 x 10 13 , 4 x 2.6 x 10 13 , 5 x 2.6 x 10 13 and 6 x 2.6 x 10 13 ion/cm 2 . Results showed that the optimum dose was 4 x 2.6 x 10 13 ion/cm 2 , and a strain M11-1A11 of high-producing GTF was obtained. Its organic Cr content was increased by 22.4% than the original strain. Its fermentation property was stable after 5 generation transfer inoculation. (authors)

Hsp40 function in yeast prion propagation: Amyloid diversity necessitates chaperone functional complexity.

Science.gov (United States)

Sporn, Zachary A; Hines, Justin K

2015-01-01

Yeast prions are heritable protein-based elements, most of which are formed of amyloid aggregates that rely on the action of molecular chaperones for transmission to progeny. Prions can form distinct amyloid structures, known as 'strains' in mammalian systems, that dictate both pathological progression and cross-species infection barriers. In yeast these same amyloid structural polymorphisms, called 'variants', dictate the intensity of prion-associated phenotypes and stability in mitosis. We recently reported that [PSI(+)] prion variants differ in the fundamental domain requirements for one chaperone, the Hsp40/J-protein Sis1, which are mutually exclusive between 2 different yeast prions, demonstrating a functional plurality for Sis1. Here we extend that analysis to incorporate additional data that collectively support the hypothesis that Sis1 has multiple functional roles that can be accomplished by distinct sets of domains. These functions are differentially required by distinct prions and prion variants. We also present new data regarding Hsp104-mediated prion elimination and show that some Sis1 functions, but not all, are conserved in the human homolog Hdj1/DNAJB1. Importantly, of the 10 amyloid-based prions indentified to date in Saccharomyces cerevisiae, the chaperone requirements of only 4 are known, leaving a great diversity of amyloid structures, and likely modes of amyloid-chaperone interaction, largely unexplored.

Genome-wide identification of pheromone-targeted transcrption in fission yeast

DEFF Research Database (Denmark)

Xue-Franzen, Y.; Kjærulff, S.; Holmberg, C.

2006-01-01

Background Fission yeast cells undergo sexual differentiation in response to nitrogen starvation. In this process haploid M and P cells first mate to form diploid zygotes, which then enter meiosis and sporulate. Prior to mating, M and P cells communicate with diffusible mating pheromones that act......Background Fission yeast cells undergo sexual differentiation in response to nitrogen starvation. In this process haploid M and P cells first mate to form diploid zygotes, which then enter meiosis and sporulate. Prior to mating, M and P cells communicate with diffusible mating pheromones...... transcription factor is responsible for the majority of pheromone-induced transcription. Finally, most cell-type specific genes now appear to be identified in fission yeast....

Tamarix hispida metallothionein-like ThMT3, a reactive oxygen species scavenger, increases tolerance against Cd(2+), Zn(2+), Cu(2+), and NaCl in transgenic yeast.

Science.gov (United States)

Yang, Jingli; Wang, Yucheng; Liu, Guifeng; Yang, Chuanping; Li, Chenghao

2011-03-01

A metallothionein-like gene, ThMT3, encoding a type 3 metallothionein, was isolated from a Tamarix hispida leaf cDNA library. Expression analysis revealed that mRNA of ThMT3 was upregulated by high salinity as well as by heavy metal ions, and that ThMT3 was predominantly expressed in the leaf. Transgenic yeast (Saccharomyces cerevisiae) expressing ThMT3 showed increased tolerance to Cd(2+), Zn(2+), Cu(2+), and NaCl stress. Transgenic yeast also accumulated more Cd(2+), Zn(2+), and NaCl, but not Cu(2+). Analysis of the expression of four genes (GLR1, GTT2, GSH1, and YCF1) that aid in transporting heavy metal (Cd(2+)) from the cytoplasm to the vacuole demonstrated that none of these genes were induced under Cd(2+), Zn(2+), Cu(2+), and NaCl stress in ThMT3-transgenic yeast. H(2)O(2) levels in transgenic yeast under such stress conditions were less than half those in control yeast under the same conditions. Three antioxidant genes (SOD1, CAT1, and GPX1) were specifically expressed under Cd(2+), Zn(2+), Cu(2+), and NaCl stress in the transgenic yeast. Cd(2+), Zn(2+), and Cu(2+) increased the expression levels of SOD1, CAT1, and GPX1, respectively, whereas NaCl induced the expression of SOD1 and GPX1.

Novel brewing yeast hybrids: creation and application.

Science.gov (United States)

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

2017-01-01

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

PREPARATION OF ZINC ENRICHED YEAST (SACCHAROMYCES CEREVISIAE BY CULTIVATION WITH DIFFERENT ZINC SALTS

Directory of Open Access Journals (Sweden)

Ľuboš Harangozo

2012-02-01

Full Text Available The yeast Saccharomyces cerevisiae is the best known microorganism and therefore widely used in many branches of industry. This study aims to investigate the accumulation of three inorganic zinc salts. Our research presents the ability of this yeast to absorb zinc from liquid medium and such enriched biomass use as a potential source of microelements in animal and/or human nutrition. It was found that the addition of different zinc forms, i.e. zinc nitrate, zinc sulphate and zinc chloride in fixed concentrations of 0, 25, 50 and 100 mg.100 ml-1 did not affect the amount of dry yeast biomass yielded, i.e. 1.0 – 1.2 g of yeast cells from 100 ml of cultivation medium, while higher presence of zinc solutions caused significantly lower yield of yeast biomass. The highest amount of zinc in yeast cells was achieved when added in the form of zinc nitrate in concentration of 200 mg.100 ml-1 YPD medium. The increment of intracellular zinc was up to 18.5 mg.g-1 of yeast biomass.

Graphene/phase change material nanocomposites: light-driven, reversible electrical resistivity regulation via form-stable phase transitions.

Science.gov (United States)

Wang, Yunming; Mi, Hongyi; Zheng, Qifeng; Ma, Zhenqiang; Gong, Shaoqin

2015-02-04

Innovative photoresponsive materials are needed to address the complexity of optical control systems. Here, we report a new type of photoresponsive nanomaterial composed of graphene and a form-stable phase change material (PCM) that exhibited a 3 orders of magnitude change in electrical resistivity upon light illumination while retaining its overall original solid form at the macroscopic level. This dramatic change in electrical resistivity also occurred reversibly through the on/off control of light illumination. This was attributed to the reversible phase transition (i.e., melting/recrystallization) behavior of the microscopic crystalline domains present in the form-stable PCM. The reversible phase transition observed in the graphene/PCM nanocomposite was induced by a reversible temperature change through the on/off control of light illumination because graphene can effectively absorb light energy and convert it to thermal energy. In addition, this graphene/PCM nanocomposite also possessed excellent mechanical properties. Such photoresponsive materials have many potential applications, including flexible electronics.

Study on thermal property of lauric–palmitic–stearic acid/vermiculite composite as form-stable phase change material for energy storage

Directory of Open Access Journals (Sweden)

Nan Zhang

2015-09-01

Full Text Available The form-stable composite phase change material of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite was prepared by vacuum impregnation method for thermal energy storage. The maximum mass fraction of lauric–palmitic–stearic acid ternary eutectic mixture retained in vermiculite was determined as 50 wt% without melted phase change material seepage from the composite phase change material. Fourier transformation infrared spectroscope and scanning electron microscope were used to characterize the structure and morphology of the prepared lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material, and the results indicate that lauric–palmitic–stearic acid ternary eutectic mixture was well confined into the layer porous structure of vermiculite by physical reaction. The melting and freezing temperatures and latent heats were measured by differential scanning calorimeter as 31.4°C and 30.3°C, and 75.8 and 73.2 J/g, respectively. Thermal cycling test showed that there was no significant change in the thermal properties of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material after 1000 thermal cycles. Moreover, 2 wt% expanded graphite was added to improve the thermal conductivity of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material. All results indicated that the prepared lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material had suitable thermal properties and good thermal reliability for the application of thermal energy storage in building energy efficiency.

Active role of a human genomic insert in replication of a yeast artificial chromosome.

Science.gov (United States)

van Brabant, A J; Fangman, W L; Brewer, B J

1999-06-01

Yeast artificial chromosomes (YACs) are a common tool for cloning eukaryotic DNA. The manner by which large pieces of foreign DNA are assimilated by yeast cells into a functional chromosome is poorly understood, as is the reason why some of them are stably maintained and some are not. We examined the replication of a stable YAC containing a 240-kb insert of DNA from the human T-cell receptor beta locus. The human insert contains multiple sites that serve as origins of replication. The activity of these origins appears to require the yeast ARS consensus sequence and, as with yeast origins, additional flanking sequences. In addition, the origins in the human insert exhibit a spacing, a range of activation efficiencies, and a variation in times of activation during S phase similar to those found for normal yeast chromosomes. We propose that an appropriate combination of replication origin density, activation times, and initiation efficiencies is necessary for the successful maintenance of YAC inserts.

Yeast: the soul of beer's aroma--a review of flavour-active esters and higher alcohols produced by the brewing yeast.

Science.gov (United States)

Pires, Eduardo J; Teixeira, José A; Brányik, Tomás; Vicente, António A

2014-03-01

Among the most important factors influencing beer quality is the presence of well-adjusted amounts of higher alcohols and esters. Thus, a heavy body of literature focuses on these substances and on the parameters influencing their production by the brewing yeast. Additionally, the complex metabolic pathways involved in their synthesis require special attention. More than a century of data, mainly in genetic and proteomic fields, has built up enough information to describe in detail each step in the pathway for the synthesis of higher alcohols and their esters, but there is still place for more. Higher alcohols are formed either by anabolism or catabolism (Ehrlich pathway) of amino acids. Esters are formed by enzymatic condensation of organic acids and alcohols. The current paper reviews the up-to-date knowledge in the pathways involving the synthesis of higher alcohols and esters by brewing yeasts. Fermentation parameters affecting yeast response during biosynthesis of these aromatic substances are also fully reviewed.

About some Regge-like relations for (stable) black holes

International Nuclear Information System (INIS)

Recami, E.; Tonin Zanchin, V.

1991-08-01

Within a purely classical formulation of ''strong gravity'', we associated hadron constituents (and even hadrons themselves) with suitable stationary, axisymmetric solutions of certain new Einstein-type equations supposed to describe the strong field inside hadrons. Such equations are nothing but Einstein equations - with cosmological term - suitably scaled down. As a consequence, the cosmological constant Λ and the masses M result in our theory to be scaled up and transformed into a ''hadronic constant'' and into ''strong masses'', respectively. Due to the unusual range of Λ and M values considered, we met a series of solutions of the Kerr-Newman-de Sitter (KNdS) type with such interesting properties that it is worth studying them - from our particular point of view - also in the case of ordinary gravity. This is the aim of the present work. The requirement that those solutions be stable, i.e., that their temperature (or surface gravity) be vanishingly small, implies the coincidence of at least two of their (in general, three) horizons. Imposing the stability condition of a certain horizon does yield (once chosen the values of J, q and Λ) mass and radius of the associated black-hole. In the case of ordinary Einstein equations and for stable black-holes of the KNdS type, we get in particular Regge-like relations among mass M, angular momentum J, charge q and cosmological constant Λ. For instance, with the standard definitions Q 2 is identical to Gq 2 /(4πε 0 c 4 ); a is identical to J/(Mc); m is identical to GM/c 2 , in the case Λ = 0 in which m 2 = a 2 + Q 2 and if q is negligible we find m 2 = J. When considering, for simplicity, Λ > 0 and J = 0 (and q still negligible), then we obtain m 2 = 1/(9Λ). In the most general case, the condition, for instance, of ''triple coincidence'' among the three horizons yields for modul Λa 2 2 = 2/(9Λ); m 2 = 8(a 2 + Q 2 )/9. Another interesting point is that - with few exceptions - all such relations (among M

The Snf1 Protein Kinase in the Yeast Saccharomyces cerevisiae

DEFF Research Database (Denmark)

Usaite, Renata

2008-01-01

4 on the regulation of glucose and galactose metabolism, I physiologically characterized Δsnf1, Δsnf4, and Δsnf1Δsnf4 CEN.PK background yeast strains in glucose and glucose-galactose mixture batch cultivations (chapter 2). The results of this study showed that delayed induction of galactose...... that the stable isotope labeling approach is 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, the major reason behind the discrepancy was the lack...

Host-derived, pore-forming toxin-like protein and trefoil factor complex protects the host against microbial infection.

Science.gov (United States)

Xiang, Yang; Yan, Chao; Guo, Xiaolong; Zhou, Kaifeng; Li, Sheng'an; Gao, Qian; Wang, Xuan; Zhao, Feng; Liu, Jie; Lee, Wen-Hui; Zhang, Yun

2014-05-06

Aerolysins are virulence factors belonging to the bacterial β-pore-forming toxin superfamily. Surprisingly, numerous aerolysin-like proteins exist in vertebrates, but their biological functions are unknown. βγ-CAT, a complex of an aerolysin-like protein subunit (two βγ-crystallin domains followed by an aerolysin pore-forming domain) and two trefoil factor subunits, has been identified in frogs (Bombina maxima) skin secretions. Here, we report the rich expression of this protein, in the frog blood and immune-related tissues, and the induction of its presence in peritoneal lavage by bacterial challenge. This phenomena raises the possibility of its involvement in antimicrobial infection. When βγ-CAT was administrated in a peritoneal infection model, it greatly accelerated bacterial clearance and increased the survival rate of both frogs and mice. Meanwhile, accelerated Interleukin-1β release and enhanced local leukocyte recruitments were determined, which may partially explain the robust and effective antimicrobial responses observed. The release of interleukin-1β was potently triggered by βγ-CAT from the frog peritoneal cells and murine macrophages in vitro. βγ-CAT was rapidly endocytosed and translocated to lysosomes, where it formed high molecular mass SDS-stable oligomers (>170 kDa). Lysosomal destabilization and cathepsin B release were detected, which may explain the activation of caspase-1 inflammasome and subsequent interleukin-1β maturation and release. To our knowledge, these results provide the first functional evidence of the ability of a host-derived aerolysin-like protein to counter microbial infection by eliciting rapid and effective host innate immune responses. The findings will also largely help to elucidate the possible involvement and action mechanisms of aerolysin-like proteins and/or trefoil factors widely existing in vertebrates in the host defense against pathogens.

Ethanol fermentation with a flocculating yeast

Energy Technology Data Exchange (ETDEWEB)

Admassu, W; Korus, R A; Heimsch, R C

1985-08-01

A 100 cm x 5.7 cm internal diameter tower fermentor was fabricated and operated continuously for 11 months using the floc-forming yeast, Saccharomyces cerevisiae (American Type Culture Collection 4097). Steady state operation of the system was characterized at 32/sup 0/C and pH 4.0 for glucose concentrations ranging from 105 to 215 g l/sup -1/. The height of the yeast bed in the tower was maintained at 80 cm. The high yeast density, ethanol concentration and low pH prevented bacterial contamination in the reactor. The concentration profiles of glucose and ethanol within the bed were described by a dispersion model. Modeling parameters were determined for the yeast by batch kinetics and tracer experiments. The kinetic model included ethanol inhibition and substrate limitation. A tracer study with step input of D-xylose (a non-metabolizable sugar for S. cerevisiae) determined the dispersion number (D/uL=0.16) and liquid voidage (epsilonsub(L)=0.25). Measurements taken after 6 months of continuous operation indicated that there was no significant change in fermentor performance.

Actin and Endocytosis in Budding Yeast

Science.gov (United States)

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

2015-01-01

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

Fungal spore germination into yeast or mycelium: possible implications of dimorphism in evolution and human pathogenesis

Science.gov (United States)

Ghormade, Vandana; Deshpande, M. V.

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

The research of moisture forms in the baking yeast by the thermogravimetric analysis method

Directory of Open Access Journals (Sweden)

S. V. Lavrov

2016-01-01

Full Text Available The thermogravimetry method is one of the few absolute methods of analysis, that makes it one of the most accurate methods. In this research, thermogravimetric analysis of baking yeast (Saccharomyces cerevisiae was carried out. It allowed to identify temperature zones, which correspond to dripping with various link energy, as well as to predict operating parameters of the process of dehumidification and to choose their most effective dehydration method. The studies were conducted in the laboratory of the collective use center "Control and management of energy efficient projects" of the "Voronezh state university of engineering technologies" on the simultaneous thermal analysis device STA 449 F3 model (NETZSCH, Germany. The device records the change in a substance mass and the difference of the heat flow inside the crucible containing the sample and the crucible containing the standard analyte. The analyzer's working principle is based on continuous recording of the dependence of the material mass on time or temperature and its being heated to the selected temperature program in a specified gas atmosphere. The release or absorption of heat by the sample due to phase transitions or chemical reactions is recorded simultaneously. The study was performed in the following modes: the pressure is atmospheric, the maximum temperature is 588 K, the rate of temperature change is 5 K/min. The experiments were performed in aluminum crucibles with a total weight of 12 mg. The software NETZSCH Proteus was used for processing of the obtained TG and DTG curves. The analysis of the obtained data allowed to identify periods of water dehydration and solids transformation by thermal effect on baking yeast, and to identify temperature zones, which correspond to the release of moisture with different link form and energy.

Structural analysis of the core COMPASS family of histone H3K4 methylases from yeast to human.

Science.gov (United States)

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

2011-12-20

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

Two-dimensional gel electrophoresis of selenized yeast and autoradiography of 75Se-containing proteins

International Nuclear Information System (INIS)

Chery, C.C.; Dumont, E.; Cornelis, R.; Moens, L.

2001-01-01

Two-dimensional high-resolution gel electrophoresis (2DE) has been applied to the fractionation of 75 Se-containing proteins in yeast, grown in 75 Se-containing medium, and autoradiography was used for detection of the 75 Se-containing proteins. Gel filtration and ultrafiltration were used to check whether the selenium side-chains were stable in the presence of the chemicals used for lysis and 2DE. The mass distribution of the selenium-containing proteins was estimated by use of gel filtration and the results were compared with the distribution obtained by 2DE. A 2DE map of selenium-containing proteins in yeast is presented, and compared with a total protein map of yeast. (orig.)

DEVELOPMENT OF MODEL FOR QUANTITATIVE EVALUATION OF DYNAMICALLY STABLE FORMS OF RIVER CHANNELS

Directory of Open Access Journals (Sweden)

O. V. Zenkin

2017-01-01

Full Text Available The article highlights the method of calculating the optimum curvature of the river channels using the kinematic model of the flow structure based on the concept of discrete nature of the channel process. It offers the analytic form of the equation of motion of river flow, which can be used simulation modeling for searching dynamically stable form of the river channel, and which can control water level in rivers. The source data for the illustrations of given in the article modeling methods have been served the images received from MODIS on the Terra satellite, for the lower reaches of the river Kur, which merges with the river Urmi, forming the Tunguska river – the left tributary of the Amur.The modified geometric method can be used to calculate obliquity of tangent to the curve and normal in those situations when observed on satellite imagery points are located on the coordinate of the network irregularly and when three points lying on the curve of the riverbed do not form isosceles triangle.The model assembles tangential and radial components of the forces acting on the water flow (centrifugal, friction and gravity. Curvature radius is explicitly expressed in the model through the parameter  – gradient angle relative to the axis X. As solution for the value of the angle  is searched, when the correlation function reaches its maximum. It is assumed that the riverbed shape “wrong” and could be modified so that the resulting curve better correlated with calculated curve. Morphometric dependences for macroforms allow creating series of morphological methods for the calculation of deformations and displacement of the shore in any section of meander scroll.The proposed technique has been tested also on satellite imagery of high resolution. The presented methods of calculation are used as the basis for hydrological projects of geoinformation systems oriented at prediction of morphodynamic processes and morphological evolution of river

Guidelines and recommendations on yeast cell death nomenclature

Directory of Open Access Journals (Sweden)

Didac Carmona-Gutierrez

2018-01-01

Full Text Available Elucidating the biology of yeast in its full complexity has major implications for science, medicine and industry. One of the most critical processes determining yeast life and physiology is cellular demise. However, the investigation of yeast cell death is a relatively young field, and a widely accepted set of concepts and terms is still missing. Here, we propose unified criteria for the definition of accidental, regulated, and programmed forms of cell death in yeast based on a series of morphological and biochemical criteria. Specifically, we provide consensus guidelines on the differential definition of terms including apoptosis, regulated necrosis, and autophagic cell death, as we refer to additional cell death routines that are relevant for the biology of (at least some species of yeast. As this area of investigation advances rapidly, changes and extensions to this set of recommendations will be implemented in the years to come. Nonetheless, we strongly encourage the authors, reviewers and editors of scientific articles to adopt these collective standards in order to establish an accurate framework for yeast cell death research and, ultimately, to accelerate the progress of this vibrant field of research.

Guidelines and recommendations on yeast cell death nomenclature

Science.gov (United States)

Carmona-Gutierrez, Didac; Bauer, Maria Anna; Zimmermann, Andreas; Aguilera, Andrés; Austriaco, Nicanor; Ayscough, Kathryn; Balzan, Rena; Bar-Nun, Shoshana; Barrientos, Antonio; Belenky, Peter; Blondel, Marc; Braun, Ralf J.; Breitenbach, Michael; Burhans, William C.; Büttner, Sabrina; Cavalieri, Duccio; Chang, Michael; Cooper, Katrina F.; Côrte-Real, Manuela; Costa, Vítor; Cullin, Christophe; Dawes, Ian; Dengjel, Jörn; Dickman, Martin B.; Eisenberg, Tobias; Fahrenkrog, Birthe; Fasel, Nicolas; Fröhlich, Kai-Uwe; Gargouri, Ali; Giannattasio, Sergio; Goffrini, Paola; Gourlay, Campbell W.; Grant, Chris M.; Greenwood, Michael T.; Guaragnella, Nicoletta; Heger, Thomas; Heinisch, Jürgen; Herker, Eva; Herrmann, Johannes M.; Hofer, Sebastian; Jiménez-Ruiz, Antonio; Jungwirth, Helmut; Kainz, Katharina; Kontoyiannis, Dimitrios P.; Ludovico, Paula; Manon, Stéphen; Martegani, Enzo; Mazzoni, Cristina; Megeney, Lynn A.; Meisinger, Chris; Nielsen, Jens; Nyström, Thomas; Osiewacz, Heinz D.; Outeiro, Tiago F.; Park, Hay-Oak; Pendl, Tobias; Petranovic, Dina; Picot, Stephane; Polčic, Peter; Powers, Ted; Ramsdale, Mark; Rinnerthaler, Mark; Rockenfeller, Patrick; Ruckenstuhl, Christoph; Schaffrath, Raffael; Segovia, Maria; Severin, Fedor F.; Sharon, Amir; Sigrist, Stephan J.; Sommer-Ruck, Cornelia; Sousa, Maria João; Thevelein, Johan M.; Thevissen, Karin; Titorenko, Vladimir; Toledano, Michel B.; Tuite, Mick; Vögtle, F.-Nora; Westermann, Benedikt; Winderickx, Joris; Wissing, Silke; Wölfl, Stefan; Zhang, Zhaojie J.; Zhao, Richard Y.; Zhou, Bing; Galluzzi, Lorenzo; Kroemer, Guido; Madeo, Frank

2018-01-01

Elucidating the biology of yeast in its full complexity has major implications for science, medicine and industry. One of the most critical processes determining yeast life and physiology is cellular demise. However, the investigation of yeast cell death is a relatively young field, and a widely accepted set of concepts and terms is still missing. Here, we propose unified criteria for the definition of accidental, regulated, and programmed forms of cell death in yeast based on a series of morphological and biochemical criteria. Specifically, we provide consensus guidelines on the differential definition of terms including apoptosis, regulated necrosis, and autophagic cell death, as we refer to additional cell death routines that are relevant for the biology of (at least some species of) yeast. As this area of investigation advances rapidly, changes and extensions to this set of recommendations will be implemented in the years to come. Nonetheless, we strongly encourage the authors, reviewers and editors of scientific articles to adopt these collective standards in order to establish an accurate framework for yeast cell death research and, ultimately, to accelerate the progress of this vibrant field of research. PMID:29354647

Monomeric Yeast Frataxin is an Iron-Binding Protein

International Nuclear Information System (INIS)

Cook, J.; Bencze, K.; Jankovic, A.; Crater, A.; Busch, C.; Bradley, P.; Stemmler, A.; Spaller, M.; Stemmler, T.

2006-01-01

Friedreich's ataxia, an autosomal cardio- and neurodegenerative disorder that affects 1 in 50 000 humans, is caused by decreased levels of the protein frataxin. Although frataxin is nuclear-encoded, it is targeted to the mitochondrial matrix and necessary for proper regulation of cellular iron homeostasis. Frataxin is required for the cellular production of both heme and iron-sulfur (Fe-S) clusters. Monomeric frataxin binds with high affinity to ferrochelatase, the enzyme involved in iron insertion into porphyrin during heme production. Monomeric frataxin also binds to Isu, the scaffold protein required for assembly of Fe-S cluster intermediates. These processes (heme and Fe-S cluster assembly) share requirements for iron, suggesting that monomeric frataxin might function as the common iron donor. To provide a molecular basis to better understand frataxin's function, we have characterized the binding properties and metal-site structure of ferrous iron bound to monomeric yeast frataxin. Yeast frataxin is stable as an iron-loaded monomer, and the protein can bind two ferrous iron atoms with micromolar binding affinity. Frataxin amino acids affected by the presence of iron are localized within conserved acidic patches located on the surfaces of both helix-1 and strand-1. Under anaerobic conditions, bound metal is stable in the high-spin ferrous state. The metal-ligand coordination geometry of both metal-binding sites is consistent with a six-coordinate iron-(oxygen/nitrogen) based ligand geometry, surely constructed in part from carboxylate and possibly imidazole side chains coming from residues within these conserved acidic patches on the protein. On the basis of our results, we have developed a model for how we believe yeast frataxin interacts with iron

Immobilization method of yeast cells for intermittent contact mode imaging using the atomic force microscope

International Nuclear Information System (INIS)

De, Tathagata; Chettoor, Antony M.; Agarwal, Pranav; Salapaka, Murti V.; Nettikadan, Saju

2010-01-01

The atomic force microscope (AFM) is widely used for studying the surface morphology and growth of live cells. There are relatively fewer reports on the AFM imaging of yeast cells (Kasas and Ikai, 1995), (Gad and Ikai, 1995). Yeasts have thick and mechanically strong cell walls and are therefore difficult to attach to a solid substrate. In this report, a new immobilization technique for the height mode imaging of living yeast cells in solid media using AFM is presented. The proposed technique allows the cell surface to be almost completely exposed to the environment and studied using AFM. Apart from the new immobilization protocol, for the first time, height mode imaging of live yeast cell surface in intermittent contact mode is presented in this report. Stable and reproducible imaging over a 10-h time span is observed. A significant improvement in operational stability will facilitate the investigation of growth patterns and surface patterns of yeast cells.

Stress tolerance and biocontrol performance of the yeast antagonist, Candida diversa, change with morphology transition.

Science.gov (United States)

Li, Guangkun; Chi, Mengshan; Chen, Huizhen; Sui, Yuan; Li, Yan; Liu, Yongsheng; Zhang, Xiaojing; Sun, Zhiqiang; Liu, Guoqing; Wang, Qi; Liu, Jia

2016-02-01

As an eco-friendly management method, biological control of postharvest diseases, utilizing antagonistic yeasts, is a research topic receiving considerable attention. Detailed knowledge on the biology of yeast antagonists is crucial when considering their potential application and development as biocontrol products. Changes in the growth form, such as single-cell to pseudohyphae, have been associated with the mode of action in postharvest biocontrol yeasts. In this study, the antagonistic yeast, Candida diversa, reversibly shifted from a single-cell morphology on yeast peptone dextrose (YPD) medium with 2 % agar to a pseudohyphal morphology on YPD with 0.3 % agar. The tolerance of the pseudohyphal form to heat and oxidative stresses, as well as the biocontrol efficacy against Botrytis cinerea on apple and kiwifruit stored at 25 and 4 °C, was significantly higher as compared to the single-cell form. This study provides new information on the ability of C. diversa to change its morphology and the impact of the morphology shift on stress tolerance and biocontrol performance.

Selection and Characterization of Potential Baker’s Yeast from Indigenous Resources of Nepal

OpenAIRE

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

2017-01-01

The study aims to isolate the yeast strains that could be used effectively as baker’s yeast and compare them with the commercial baker’s yeast available in the market of Nepal. A total of 10 samples including locally available sources like fruits, Murcha, and a local tree “Dar” were collected from different localities of Bhaktapur, Kavre, and Syangja districts of Nepal, respectively. Following enrichment and fermentation of the samples, 26 yeast strains were isolated using selective medium Wa...

Structures of two exonucleases involved in controlled RNA turnover in yeast

DEFF Research Database (Denmark)

Jonstrup, Anette Thyssen; Midtgaard, Søren Fuglsang; Van, Lan Bich

divalent cations. The Pop2p structure reveals that the ability of this enzyme to degrade poly(A)/(U)/(C), but not poly(G) may be determined by structural hindrance of interaction with this specific nucleotide. In Rrp6p, mutations known to confer specific RNA degradation phenotypes in yeast nuclei can now...... rid of aberrant RNAs. Here we describe the structures of two 3'-5' exonucleases involved in controlled RNA decay in yeast, Pop2p and Rrp6p. Rrp6p is associated with the nuclear exosome where it participates in the degradation of improperly processed precursor mRNAs and trimming of stable RNAs [1]. Pop...

Evolution of multinucleated Ashbya gossypii hyphae from a budding yeast-like ancestor.

Science.gov (United States)

Schmitz, Hans-Peter; Philippsen, Peter

2011-06-01

In the filamentous ascomycete Ashbya gossypii polarity establishment at sites of germ tube and lateral branch emergence depends on homologues of Saccharomyces cerevisiae factors controlling bud site selection and bud emergence. Maintenance of polar growth involves homologues of well-known polarity factors of budding yeast. To achieve the much higher rates of sustained polar surface expansion of hyphae compared to mainly non-polarly growing yeast buds five important alterations had to evolve. Permanent presence of the polarity machinery at a confined area in the rapidly expanding hyphal tip, increased cytoplasmic space with a much enlarged ER surface for generating secretory vesicles, efficient directed transport of secretory vesicles to and accumulation at the tip, increased capacity of the exocytosis system to process these vesicles, and an efficient endocytosis system for membrane and polarity factor recycling adjacent to the zone of exocytosis. Morphological, cell biological, and molecular aspects of this evolution are discussed based on experiments performed within the past 10 y. Copyright © 2011 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

The ecology of insect-yeast relationships and its relevance to human industry.

Science.gov (United States)

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

2018-03-28

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

Distinct Domestication Trajectories in Top-Fermenting Beer Yeasts and Wine Yeasts.

Science.gov (United States)

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

2016-10-24

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

Metabolic engineering of a haploid strain derived from a triploid industrial yeast for producing cellulosic ethanol.

Science.gov (United States)

Kim, Soo Rin; Skerker, Jeffrey M; Kong, In Iok; Kim, Heejin; Maurer, Matthew J; Zhang, Guo-Chang; Peng, Dairong; Wei, Na; Arkin, Adam P; Jin, Yong-Su

2017-03-01

Many desired phenotypes for producing cellulosic biofuels are often observed in industrial Saccharomyces cerevisiae strains. However, many industrial yeast strains are polyploid and have low spore viability, making it difficult to use these strains for metabolic engineering applications. We selected the polyploid industrial strain S. cerevisiae ATCC 4124 exhibiting rapid glucose fermentation capability, high ethanol productivity, strong heat and inhibitor tolerance in order to construct an optimal yeast strain for producing cellulosic ethanol. Here, we focused on developing a general approach and high-throughput screening method to isolate stable haploid segregants derived from a polyploid parent, such as triploid ATCC 4124 with a poor spore viability. Specifically, we deleted the HO genes, performed random sporulation, and screened the resulting segregants based on growth rate, mating type, and ploidy. Only one stable haploid derivative (4124-S60) was isolated, while 14 other segregants with a stable mating type were aneuploid. The 4124-S60 strain inherited only a subset of desirable traits present in the parent strain, same as other aneuploids, suggesting that glucose fermentation and specific ethanol productivity are likely to be genetically complex traits and/or they might depend on ploidy. Nonetheless, the 4124-60 strain did inherit the ability to tolerate fermentation inhibitors. When additional genetic perturbations known to improve xylose fermentation were introduced into the 4124-60 strain, the resulting engineered strain (IIK1) was able to ferment a Miscanthus hydrolysate better than a previously engineered laboratory strain (SR8), built by making the same genetic changes. However, the IIK1 strain showed higher glycerol and xylitol yields than the SR8 strain. In order to decrease glycerol and xylitol production, an NADH-dependent acetate reduction pathway was introduced into the IIK1 strain. By consuming 2.4g/L of acetate, the resulting strain (IIK1A

Prions in yeast

OpenAIRE

Bezdíčka, Martin

2013-01-01

The thesis describes yeast prions and their biological effects on yeast in general. It defines the basic characteristics of yeast prions, that distinguish prions from other proteins. The thesis introduces various possibilities of prion formation, and propagation as well as specific types of yeast prions, including various functions of most studied types of prions. The thesis also focuses on chaperones that affect the state of yeast prions in cells. Lastly, the thesis indicates similarities be...

Components of a Fanconi-like pathway control Pso2-independent DNA interstrand crosslink repair in yeast.

Directory of Open Access Journals (Sweden)

Thomas A Ward

Full Text Available Fanconi anemia (FA is a devastating genetic disease, associated with genomic instability and defects in DNA interstrand cross-link (ICL repair. The FA repair pathway is not thought to be conserved in budding yeast, and although the yeast Mph1 helicase is a putative homolog of human FANCM, yeast cells disrupted for MPH1 are not sensitive to ICLs. Here, we reveal a key role for Mph1 in ICL repair when the Pso2 exonuclease is inactivated. We find that the yeast FANCM ortholog Mph1 physically and functionally interacts with Mgm101, a protein previously implicated in mitochondrial DNA repair, and the MutSα mismatch repair factor (Msh2-Msh6. Co-disruption of MPH1, MGM101, MSH6, or MSH2 with PSO2 produces a lesion-specific increase in ICL sensitivity, the elevation of ICL-induced chromosomal rearrangements, and persistence of ICL-associated DNA double-strand breaks. We find that Mph1-Mgm101-MutSα directs the ICL-induced recruitment of Exo1 to chromatin, and we propose that Exo1 is an alternative 5'-3' exonuclease utilised for ICL repair in the absence of Pso2. Moreover, ICL-induced Rad51 chromatin loading is delayed when both Pso2 and components of the Mph1-Mgm101-MutSα and Exo1 pathway are inactivated, demonstrating that the homologous recombination stages of ICL repair are inhibited. Finally, the FANCJ- and FANCP-related factors Chl1 and Slx4, respectively, are also components of the genetic pathway controlled by Mph1-Mgm101-MutSα. Together this suggests that a prototypical FA-related ICL repair pathway operates in budding yeast, which acts redundantly with the pathway controlled by Pso2, and is required for the targeting of Exo1 to chromatin to execute ICL repair.

Earth's first stable continents did not form by subduction.

Science.gov (United States)

Johnson, Tim E; Brown, Michael; Gardiner, Nicholas J; Kirkland, Christopher L; Smithies, R Hugh

2017-03-09

The geodynamic environment in which Earth's first continents formed and were stabilized remains controversial. Most exposed continental crust that can be dated back to the Archaean eon (4 billion to 2.5 billion years ago) comprises tonalite-trondhjemite-granodiorite rocks (TTGs) that were formed through partial melting of hydrated low-magnesium basaltic rocks; notably, these TTGs have 'arc-like' signatures of trace elements and thus resemble the continental crust produced in modern subduction settings. In the East Pilbara Terrane, Western Australia, low-magnesium basalts of the Coucal Formation at the base of the Pilbara Supergroup have trace-element compositions that are consistent with these being source rocks for TTGs. These basalts may be the remnants of a thick (more than 35 kilometres thick), ancient (more than 3.5 billion years old) basaltic crust that is predicted to have existed if Archaean mantle temperatures were much hotter than today's. Here, using phase equilibria modelling of the Coucal basalts, we confirm their suitability as TTG 'parents', and suggest that TTGs were produced by around 20 per cent to 30 per cent melting of the Coucal basalts along high geothermal gradients (of more than 700 degrees Celsius per gigapascal). We also analyse the trace-element composition of the Coucal basalts, and propose that these rocks were themselves derived from an earlier generation of high-magnesium basaltic rocks, suggesting that the arc-like signature in Archaean TTGs was inherited from an ancestral source lineage. This protracted, multistage process for the production and stabilization of the first continents-coupled with the high geothermal gradients-is incompatible with modern-style plate tectonics, and favours instead the formation of TTGs near the base of thick, plateau-like basaltic crust. Thus subduction was not required to produce TTGs in the early Archaean eon.

Multigene phylogeny and taxonomic revision of yeasts and related fungi in the Ustilaginomycotina

NARCIS (Netherlands)

Wang, Q. -M.; Begerow, D.; Groenewald, M.; Liu, X. -Z.; Theelen, B.; Bai, F. -Y.; Boekhout, T.

The subphylum Ustilaginomycotina (Basidiomycota, Fungi) comprises mainly plant pathogenic fungi (smuts). Some of the lineages possess cultivable unicellular stages that are usually classified as yeast or yeast-like species in a largely artificial taxonomic system which is independent from and

Epoxy-Based Organogels for Thermally Reversible Light Scattering Films and Form-Stable Phase Change Materials.

Science.gov (United States)

Puig, Julieta; Dell' Erba, Ignacio E; Schroeder, Walter F; Hoppe, Cristina E; Williams, Roberto J J

2017-03-29

Alkyl chains of β-hydroxyesters synthesized by the capping of terminal epoxy groups of diglycidylether of bisphenol A (DGEBA) with palmitic (C16), stearic (C18), or behenic (C22) fatty acids self-assemble forming a crystalline phase. Above a particular concentration solutions of these esters in a variety of solvents led to supramolecular (physical) gels below the crystallization temperature of alkyl chains. A form-stable phase change material (FS-PCM) was obtained by blending the ester derived from behenic acid with eicosane. A blend containing 20 wt % ester was stable as a gel up to 53 °C and exhibited a heat storage capacity of 161 J/g, absorbed during the melting of eicosane at 37 °C. Thermally reversible light scattering (TRLS) films were obtained by visible-light photopolymerization of poly(ethylene glycol) dimethacrylate-ester blends (50 wt %) in the gel state at room temperature. The reaction was very fast and not inhibited by oxygen. TRLS films consisted of a cross-linked methacrylic network interpenetrated by the supramolecular network formed by the esters. Above the melting temperature of crystallites formed by alkyl chains, the film was transparent due to the matching between refractive indices of the methacrylic network and the amorphous ester. Below the crystallization temperature, the film was opaque because of light dispersion produced by the organic crystallites uniformly dispersed in the material. Of high significance for application was the fact that the contrast ratio did not depend on heating and cooling rates.

Preparation and properties studies of halogen-free flame retardant form-stable phase change materials based on paraffin/high density polyethylene composites

International Nuclear Information System (INIS)

Cai Yibing; Wei Qufu; Huang Fenglin; Gao Weidong

2008-01-01

The halogen-free flame retardant form-stable phase change materials (PCM) based on paraffin/high density polyethylene (HDPE) composites were prepared by using twin-screw extruder technique. The structures and properties of the form-stable PCM composites based on intumescent flame retardant system with expandable graphite (EG) and different synergistic additives, such as ammonium polyphosphate (APP) and zinc borate (ZB) were characterized by scanning electronic microscope (SEM), thermogravimetric analyses (TGA), dynamic Fourier-transform infrared (FTIR) spectra, differential scanning calorimeter (DSC) and Cone calorimeter test. The TGA results showed that the halogen-free flame retardant form-stable PCM composites produced a larger amount of charred residue at 700 deg. C, although the onset of weight loss of the halogen-free flame retardant form-stable PCM composites occurred at a lower temperature due to the thermal decomposition of flame retardant. The DSC measurements indicated that the additives of flame retardant had little effect on the thermal energy storage property, and the temperatures of phase change peaks and the latent heat of the paraffin showed better occurrence during the freezing process. The dynamic FTIR monitoring results revealed that the breakdowns of main chains (HDPE and paraffin) and formations of various residues increased with increasing thermo-oxidation temperature. It was also found from the Cone calorimeter tests that the peak of heat release rate (PHRR) decreased significantly. Both the decrease of the PHRR and the structure of charred residue after combustion indicated that there was a synergistic effect between the EG and APP, contributing to the improved flammability of the halogen-free flame retardant form-stable PCM composites

Yeast genomics on food flavours

NARCIS (Netherlands)

Schoondermark-Stolk, Sung Ah

2005-01-01

The appearance and concentration of the fusel alcohol 3-methyl-1-butanol is important for the flavour of fermented foods. 3-Methyl-1-butanol is formed by yeast during the conversion of L-leucine. Identification of the enzymes and genes involved in the formation of 3-methyl-1-butanol is a major

Feasibility studies of time-like proton electromagnetic form factors at PANDA-FAIR

Energy Technology Data Exchange (ETDEWEB)

Dbeyssi, Alaa; Capozza, Luigi; Deiseroth, Malte; Froehlich, Bertold; Khaneft, Dmitry; Mora Espi, Maria Carmen; Noll, Oliver; Rodriguez Pineiro, David; Valente, Roserio; Zambrana, Manuel; Zimmermann, Iris [Helmholtz-Institut Mainz, Mainz (Germany); Maas, Frank [Helmholtz-Institut Mainz, Mainz (Germany); Institute of Nuclear Physics, Mainz (Germany); PRISMA Cluster of Excellence, Mainz (Germany); Marchand, Dominique; Tomasi-Gustafsson, Egle; Wang, Ying [Institut de Physique Nucleaire, Orsay (France); Collaboration: PANDA-Collaboration

2015-07-01

Electromagnetic form factors are fundamental quantities which describe the intrinsic electric and magnetic distributions of hadrons. Time-like proton form factors are experimentally accessible through the annihilation processes anti p+p <-> e{sup +}+e{sup -}. Their measurement in the time-like region had been limited by the low statistics achieved by the experiments. This contribution reports on the results of Monte Carlo simulations for future measurements of electromagnetic proton form factors at PANDA (antiProton ANnihilation at DArmstadt). In frame of the PANDARoot software, the statistical precision at which the proton form factors will be determined is estimated. The signal (anti p+p → e{sup +}+e{sup -}) identification and the suppression of the main background process (anti p+p → π{sup +}+π{sup -}) are studied. Different methods have been used and/or developed to generate and analyse the processes of interest. The results show that time-like proton form factors will be measured at PANDA with unprecedented statistical accuracy.

Bioavailability of selenium from fish, yeast and selenate: A comparative study in humans using stable isotopes

NARCIS (Netherlands)

Fox, T.E.; Heuvel, E.G.H.M. van den; Atherton, C.A.; Dainty, J.R.; Lewis, D.J.; Langford, N.J.; Crews, H.M.; Luten, J.B.; Lorentzen, M.; Sieling, F.W.; Aken-Schneyder, P. van; Hoek, M.; Kotterman, M.J.J.; Dael, P. van; Firweather-Tail, S.J.

2004-01-01

Objective: To measure the bioavailability of selenium from cooked and raw fish in humans by estimating and comparing apparent absorption and retention of selenium in biosynthetically labelled fish with labelled selenate and biosynthetically labelled selenium in brewers yeast. Design: The

Bioavailibility of selenium from fish, yeast and selenate: a comparative study in humans using stable isotopes

NARCIS (Netherlands)

Fox, T.E.; Heuvel, van den E.G.H.M.; Atherton, C.A.; Luten, J.B.; Hoek-van Nieuwenhuizen, van M.; Kotterman, M.J.J.

2004-01-01

Objective: To measure the bioavailability of selenium from cooked and raw fish in humans by estimating and comparing apparent absorption and retention of selenium in biosynthetically labelled fish with labelled selenate and biosynthetically labelled selenium in brewers yeast. Design: The

Dietary glucose regulates yeast consumption in adult Drosophila males.

Science.gov (United States)

Lebreton, Sébastien; Witzgall, Peter; Olsson, Marie; Becher, Paul G

2014-01-01

The adjustment of feeding behavior in response to hunger and satiety contributes to homeostatic regulation in animals. The fruit fly Drosophila melanogaster feeds on yeasts growing on overripe fruit, providing nutrients required for adult survival, reproduction and larval growth. Here, we present data on how the nutritional value of food affects subsequent yeast consumption in Drosophila adult males. After a period of starvation, flies showed intensive yeast consumption. In comparison, flies stopped feeding after having access to a nutritive cornmeal diet. Interestingly, dietary glucose was equally efficient as the complex cornmeal diet. In contrast, flies fed with sucralose, a non-metabolizable sweetener, behaved as if they were starved. The adipokinetic hormone and insulin-like peptides regulate metabolic processes in insects. We did not find any effect of the adipokinetic hormone pathway on this modulation. Instead, the insulin pathway was involved in these changes. Flies lacking the insulin receptor (InR) did not respond to nutrient deprivation by increasing yeast consumption. Together these results show the importance of insulin in the regulation of yeast consumption in response to starvation in adult D. melanogaster males.

The 26S Proteasome Degrades the Soluble but Not the Fibrillar Form of the Yeast Prion Ure2p In Vitro.

Directory of Open Access Journals (Sweden)

Kai Wang

Full Text Available Yeast prions are self-perpetuating protein aggregates that cause heritable and transmissible phenotypic traits. Among these, [PSI+] and [URE3] stand out as the most studied yeast prions, and result from the self-assembly of the translation terminator Sup35p and the nitrogen catabolism regulator Ure2p, respectively, into insoluble fibrillar aggregates. Protein quality control systems are well known to govern the formation, propagation and transmission of these prions. However, little is known about the implication of the cellular proteolytic machineries in their turnover. We previously showed that the 26S proteasome degrades both the soluble and fibrillar forms of Sup35p and affects [PSI+] propagation. Here, we show that soluble native Ure2p is degraded by the proteasome in an ubiquitin-independent manner. Proteasomal degradation of Ure2p yields amyloidogenic N-terminal peptides and a C-terminal resistant fragment. In contrast to Sup35p, fibrillar Ure2p resists proteasomal degradation. Thus, structural variability within prions may dictate their ability to be degraded by the cellular proteolytic systems.

The 26S Proteasome Degrades the Soluble but Not the Fibrillar Form of the Yeast Prion Ure2p In Vitro

Science.gov (United States)

Wang, Kai; Redeker, Virginie; Madiona, Karine; Melki, Ronald; Kabani, Mehdi

2015-01-01

Yeast prions are self-perpetuating protein aggregates that cause heritable and transmissible phenotypic traits. Among these, [PSI +] and [URE3] stand out as the most studied yeast prions, and result from the self-assembly of the translation terminator Sup35p and the nitrogen catabolism regulator Ure2p, respectively, into insoluble fibrillar aggregates. Protein quality control systems are well known to govern the formation, propagation and transmission of these prions. However, little is known about the implication of the cellular proteolytic machineries in their turnover. We previously showed that the 26S proteasome degrades both the soluble and fibrillar forms of Sup35p and affects [PSI +] propagation. Here, we show that soluble native Ure2p is degraded by the proteasome in an ubiquitin-independent manner. Proteasomal degradation of Ure2p yields amyloidogenic N-terminal peptides and a C-terminal resistant fragment. In contrast to Sup35p, fibrillar Ure2p resists proteasomal degradation. Thus, structural variability within prions may dictate their ability to be degraded by the cellular proteolytic systems. PMID:26115123

Characterization of the yeast form symbiant of Togosodes orizicolus (Hemiptera: delphacidae), vector of the rice white leaf virus

International Nuclear Information System (INIS)

Xet Mull, A.M.

1997-01-01

The purpose of this investigation was to characterize the yeast forms symbionts of Togo soles Orizicolus (YLSTo), through its morphologic description and locating in situ through microscopy of light, electronic microscopy of transmission and of sweeping and immuno microscopy. Likewise, molecular tests were carried out to classify phylogenetically the symbionts, utilizing partial sequences of the ribosomal DNA 18S. This study will permit to determine, the existence or not of interactions among the YLSTo and the insect vector, in the future. The paper of that interaction in the mechanism of trans ovarial transmission of the virus and the search of alternatives for the control of the disease in the rice. (S. Grainger) [es

Identification of salivary components that induce transition of hyphae to yeast in Candida albicans.

Science.gov (United States)

Leito, Jelani T D; Ligtenberg, Antoon J M; Nazmi, Kamran; Veerman, Enno C I

2009-10-01

Candida albicans, the major human fungal pathogen, undergoes a reversible morphological transition from single yeast cells to pseudohyphae and hyphae filaments. The hyphae form is considered the most invasive form of the fungus. The purpose of this study is to investigate the effect of saliva on hyphae growth of C. albicans. Candida albicans hyphae were inoculated in Roswell Park Memorial Institute medium with whole saliva, parotid saliva or buffer mimicking the saliva ion composition, and cultured for 18 h at 37 degrees C under aerobic conditions with 5% CO(2). Whole saliva and parotid saliva induced transition to yeast growth, whereas the culture with buffer remained in the hyphae form. Parotid saliva was fractionated on a reverse-phase C8 column and each fraction was tested for inducing transition to yeast growth. By immunoblotting, the salivary component in the active fraction was identified as statherin, a phosphoprotein of 43 amino acids that has been implicated in remineralization of the teeth. Synthetically made statherin induced transition of hyphae to yeast. By deletion of five amino acids at the negatively charged N-terminal site (DpSpSEE), yeast-inducing activity and binding to C. albicans were increased. In conclusion, statherin induces transition to yeast of C. albicans hyphae and may thus contribute to the oral defense against candidiasis.

The yeast spectrum of the 'tea fungus Kombucha'.

Science.gov (United States)

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

1995-01-01

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

Radiation stimulation of yeast crops for increasing output of alcohol and baker yeasts

International Nuclear Information System (INIS)

Vlad, E.; Marsheu, P.

1974-01-01

The purpose of this study was to stimulate by gamma radiation the existing commercial types of yeast so as to obtain yeasts that would better reflect the substrate and have improved reproductive capacity. The experiments were conducted under ordinary conditions using commercial yeasts received from one factory producing alcohol and bakery yeasts and isolated as pure cultures. Irradiating yeast cultures with small doses (up to 10 krad) was found to stimulate the reproduction and fermenting activity of yeast cells as manifested in increased accumulation of yeast biomass and greater yield of ethyl alcohol. (E.T.)

Form-stable paraffin/high density polyethylene composites as solid-liquid phase change material for thermal energy storage: preparation and thermal properties

International Nuclear Information System (INIS)

Sari, Ahmet

2004-01-01

This paper deals with the preparation of paraffin/high density polyethylene (HDPE) composites as form-stable, solid-liquid phase change material (PCM) for thermal energy storage and with determination of their thermal properties. In such a composite, the paraffin (P) serves as a latent heat storage material and the HDPE acts as a supporting material, which prevents leakage of the melted paraffin because of providing structural strength. Therefore, it is named form-stable composite PCM. In this study, two kinds of paraffins with melting temperatures of 42-44 deg. C (type P1) and 56-58 deg. C (type P2) and latent heats of 192.8 and 212.4 J g -1 were used. The maximum weight percentage for both paraffin types in the PCM composites without any seepage of the paraffin in the melted state were found as high as 77%. It is observed that the paraffin is dispersed into the network of the solid HDPE by investigation of the structure of the composite PCMs using a scanning electronic microscope (SEM). The melting temperatures and latent heats of the form-stable P1/HDPE and P2/HDPE composite PCMs were determined as 37.8 and 55.7 deg. C, and 147.6 and 162.2 J g -1 , respectively, by the technique of differential scanning calorimetry (DSC). Furthermore, to improve the thermal conductivity of the form-stable P/HDPE composite PCMs, expanded and exfoliated graphite (EG) by heat treatment was added to the samples in the ratio of 3 wt.%. Thereby, the thermal conductivity was increased about 14% for the form-stable P1/HDPE and about 24% for the P2/HDPE composite PCMs. Based on the results, it is concluded that the prepared form-stable P/HDPE blends as composite type PCM have great potential for thermal energy storage applications in terms of their satisfactory thermal properties and improved thermal conductivity. Furthermore, these composite PCMs added with EG can be considered cost effective latent heat storage materials since they do not require encapsulation and extra cost to enhance

The genome of wine yeast Dekkera bruxellensis provides a tool to explore its food-related properties

Energy Technology Data Exchange (ETDEWEB)

Piskur, Jure; Ling, Zhihao; Marcet-Houben, Marina; Ishchuk, Olena P.; Aerts, Andrea; LaButti, Kurt; Copeland, Alex; Lindquist, Erika; Barry, Kerrie; Compagno, Concetta; Bisson, Linda; Grigoriev, Igor V.; Gabaldon, Toni; Phister, Trevor

2012-03-14

The yeast Dekkera/Brettanomyces bruxellensis can cause enormous economic losses in wine industry due to production of phenolic off-flavor compounds. D. bruxellensis is a distant relative of baker's yeast Saccharomyces cerevisiae. Nevertheless, these two yeasts are often found in the same habitats and share several food-related traits, such as production of high ethanol levels and ability to grow without oxygen. In some food products, like lambic beer, D. bruxellensis can importantly contribute to flavor development. We determined the 13.4 Mb genome sequence of the D. bruxellensis strain Y879 (CBS2499) and deduced the genetic background of several ?food-relevant? properties and evolutionary history of this yeast. Surprisingly, we find that this yeast is phylogenetically distant to other food-related yeasts and most related to Pichia (Komagataella) pastoris, which is an aerobic poor ethanol producer. We further show that the D. bruxellensis genome does not contain an excess of lineage specific duplicated genes nor a horizontally transferred URA1 gene, two crucial events that promoted the evolution of the food relevant traits in the S. cerevisiae lineage. However, D. bruxellensis has several independently duplicated ADH and ADH-like genes, which are likely responsible for metabolism of alcohols, including ethanol, and also a range of aromatic compounds.

Polymorphic drugs examined with neutron spectroscopy: Is making more stable forms really that simple?

Science.gov (United States)

Tsapatsaris, Nikolaos; Landsgesell, Sven; Koza, Michael M.; Frick, Bernhard; Boldyreva, Elena V.; Bordallo, Heloisa N.

2013-12-01

Understanding polymorphism in pharmaceutical ingredients is a long-standing challenge in formulation science. A well-known example is paracetamol, C8H9NO2. The marketed stable form I crystallizes with corrugated molecular layers. In contrast, form II, which is thermodynamically favorable at high pressures, has relatively planar layers that can slip over each other without difficulty, but is metastable at ambient conditions. By means of inelastic neutron scattering we demonstrated that the lattice modes of form II exhibit a sudden 1 meV energy shift at 300 K under a pressure of ca 0.4 GPa. Moreover, evidence of an increase of the vibrational energy in both polymorphs was found, which was accompanied, in form I, by an unexpectedly weak increase of the tunnel splitting. These results indicate an anisotropy of the potential surface probed by the methyl rotor, and are discussed in relation to the differences of the strength of the hydrogen bond environment for each polymorph.

'Yeast mail': a novel Saccharomyces application (NSA) to encrypt messages.

Science.gov (United States)

Rosemeyer, Helmut; Paululat, Achim; Heinisch, Jürgen J

2014-09-01

The universal genetic code is used by all life forms to encode biological information. It can also be used to encrypt semantic messages and convey them within organisms without anyone but the sender and recipient knowing, i.e., as a means of steganography. Several theoretical, but comparatively few experimental, approaches have been dedicated to this subject, so far. Here, we describe an experimental system to stably integrate encrypted messages within the yeast genome using a polymerase chain reaction (PCR)-based, one-step homologous recombination system. Thus, DNA sequences encoding alphabetical and/or numerical information will be inherited by yeast propagation and can be sent in the form of dried yeast. Moreover, due to the availability of triple shuttle vectors, Saccharomyces cerevisiae can also be used as an intermediate construction device for transfer of information to either Drosophila or mammalian cells as steganographic containers. Besides its classical use in alcoholic fermentation and its modern use for heterologous gene expression, we here show that baker's yeast can thus be employed in a novel Saccharomyces application (NSA) as a simple steganographic container to hide and convey messages. Copyright © 2014 Verlag Helvetica Chimica Acta AG, Zürich.

Yeast and Fungal Prions: Amyloid-Handling Systems, Amyloid Structure, and Prion Biology.

Science.gov (United States)

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

2016-01-01

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

MLKL forms disulfide bond-dependent amyloid-like polymers to induce necroptosis.

Science.gov (United States)

Liu, Shuzhen; Liu, Hua; Johnston, Andrea; Hanna-Addams, Sarah; Reynoso, Eduardo; Xiang, Yougui; Wang, Zhigao

2017-09-05

Mixed-lineage kinase domain-like protein (MLKL) is essential for TNF-α-induced necroptosis. How MLKL promotes cell death is still under debate. Here we report that MLKL forms SDS-resistant, disulfide bond-dependent polymers during necroptosis in both human and mouse cells. MLKL polymers are independent of receptor-interacting protein kinase 1 and 3 (RIPK1/RIPK3) fibers. Large MLKL polymers are more than 2 million Da and are resistant to proteinase K digestion. MLKL polymers are fibers 5 nm in diameter under electron microscopy. Furthermore, the recombinant N-terminal domain of MLKL forms amyloid-like fibers and binds Congo red dye. MLKL mutants that cannot form polymers also fail to induce necroptosis efficiently. Finally, the compound necrosulfonamide conjugates cysteine 86 of human MLKL and blocks MLKL polymer formation and subsequent cell death. These results demonstrate that disulfide bond-dependent, amyloid-like MLKL polymers are necessary and sufficient to induce necroptosis.

Mapping out starvation responses in yeast by proteomics

DEFF Research Database (Denmark)

Rødkær, Steven Vestergaard; Færgeman, Nils J.; Andersen, Jens S.

2011-01-01

that are involved in this positive outcome. Based on that, processes like autophagy, lipid turnover and the generation/clearance of reactive oxygen species (ROS) have all been describe to affect life span, either alone, or in a not fully characterized interplay. The baker’s yeast Saccharomyces cerevisae is by now...... the organism with the best characterized proteome and is therefore the organism of choice in many proteomic studies. Additionally, this single-celled organism exhibits many conserved proteins and pathways of higher animals, thus observations in the yeast might reveal important information applying to other...

Genetical control of mitotic crossing over in yeast

International Nuclear Information System (INIS)

Fedorova, I.V.; Marfin, A.B.

1982-01-01

Lethal effect of 8 methoxypsoralen (8-MOP) and long-wave ultraviolet radiation (LUR) on diploid and haploid radiosensitive strains of yeast LSaccharomyces cerevisiae has been studied. It is shown that wild type diploids and homozygous with respect to locus rad 2 is considerably more stable than corresponding haploids, while diploid homozygous with respect to rad 54 locus is more sensitive than haploid. Use of the method of repeated irradiation permitted to study capability of radiosensitive diploids to remove 8 MOP-induced DNA photodamages-monoadducts. This process proceeds effectively in the wild type strain and rad 54 rad 54 diploid and was absent in rad 2 rad 2 diploid. Very strong recombinogenous effect of 8-MOP and LUR was discovered when studying mitotic segregation and crossing-over. It is also shown that rad 2 mutation increases slightly and rad 54 mutation decreases sharply frequency of recombination events in yeast cells. It is established by means of the repeated irradiation method that the main contribution to the 8 MOP and LUR recombinogenous effect is made with DNA sutures induced with these agents. Possible participation of different repair systems in the recombination processes induced with 8 MOP and LUR in yeast cells is discussed

Nectar yeasts in the tall Larkspur Delphinium barbeyi (Ranunculaceae and effects on components of pollinator foraging behavior.

Directory of Open Access Journals (Sweden)

Robert N Schaeffer

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

Nectar Yeasts in the Tall Larkspur Delphinium barbeyi (Ranunculaceae) and Effects on Components of Pollinator Foraging Behavior

Science.gov (United States)

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

2014-01-01

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

The primary structures of two yeast enolase genes. Homology between the 5' noncoding flanking regions of yeast enolase and glyceraldehyde-3-phosphate dehydrogenase genes.

Science.gov (United States)

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

1981-02-10

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

Crystal Structure of the Yeast Nicotinamidase Pnc1p

OpenAIRE

Hu, Gang; Taylor, Alexander B.; McAlister-Henn, Lee; Hart, P. John

2007-01-01

The yeast nicotinamidase Pnc1p acts in transcriptional silencing by reducing levels of nicotinamide, an inhibitor of the histone deacetylase Sir2p. The Pnc1p structure was determined at 2.9 Å resolution using MAD and MIRAS phasing methods after inadvertent crystallization during the pursuit of the structure of histidine-tagged yeast isocitrate dehydrogenase (IDH). Pnc1p displays a cluster of surface histidine residues likely responsible for its co-fractionation with IDH from Ni2+-coupled chro...

PEG/SiO{sub 2}–Al{sub 2}O{sub 3} hybrid form-stable phase change materials with enhanced thermal conductivity

Energy Technology Data Exchange (ETDEWEB)

Tang, Bingtao, E-mail: tangbt@dlut.edu.cn; Wu, Cheng; Qiu, Meige; Zhang, Xiwen; Zhang, Shufen

2014-03-01

The thermal conductivity of form-stable PEG/SiO{sub 2} phase change material (PCM) was enhanced by in situ doping of Al{sub 2}O{sub 3} using an ultrasound-assisted sol–gel method. Fourier transform infrared spectroscopy (FT-IR) was used to characterize the structure, and the crystal performance was characterized by the X-ray diffraction (XRD). Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) were used to determine the thermal properties. The phase change enthalpy of PEG/SiO{sub 2}–Al{sub 2}O{sub 3} reached 124 J g{sup −1}, and thermal conductivity improved by 12.8% for 3.3 wt% Al{sub 2}O{sub 3} in the PCM compared with PEG/SiO{sub 2}. The hybrid PCM has excellent thermal stability and form-stable effects. - Highlights: • The PEG/SiO{sub 2}–Al{sub 2}O{sub 3} hybrid form-stable phase change material (PCM) was obtained through the sol–gel method. • The inexpensive aluminum nitrate and tetraethyl orthosilicate were used as sol precursors. • This organic–inorganic hybrid process can effectively enhance the thermal conductivity of PCMs. • The PCM exhibited high thermal stability and excellent form-stable effects.

mRNA processing in yeast

International Nuclear Information System (INIS)

Stevens, A.

1982-01-01

Investigations in this laboratory center on basic enzymatic reactions of RNA. Still undefined are reactions involved in the conversion of precursors of mRA (pre-mRNA) to mRNA in eukaryotes. The pre-mRNA is called heterogeneous nuclear RNA and is 2 to 6 times larger than mRNA. The conversion, called splicing, involves a removal of internal sequences called introns by endoribonuclease action followed by a rejoining of the 3'- and 5'-end fragments, called exons, by ligating activity. It has not been possible yet to study the enzymes involved in vitro. Also undefined are reactions involved in the turnover or discarding of certain of the pre-mRNA molecules. Yeast is a simple eukaryote and may be expected to have the same, but perhaps simpler, processing reactions as the higher eukaryotes. Two enzymes involved in the processing of pre-mRNA and mRNA in yeast are under investigation. Both enzymes have been partially purified from ribonucleoprotein particles of yeast. The first is a unique decapping enzyme which cleaves [ 3 H]m 7 Gppp [ 14 C]RNA-poly (A) of yeast, yielding [ 3 H]m 7 GDP and is suggested by the finding that the diphosphate product, m 7 GpppA(G), and UDP-glucose are not hydrolyzed. The second enzyme is an endoribonuclease which converts both the [ 3 H] and [ 14 C] labels of [ 3 H]m 7 Gppp[ 14 C]RNA-poly(A) from an oligo(dT)-cellulose bound form to an unbound, acid-insoluble form. Results show that the stimulation involves an interaction of the labeled RNA with the small nuclear RNA. The inhibition of the enzyme by ethidium bromide and its stimulation by small nuclear RNA suggest that it may be a processing ribonuclease, requiring specific double-stranded features in its substrate. The characterization of the unique decapping enzyme and endoribonuclease may help to understand reactions involved in the processing of pre-mRNA and mRNA in eukaryotes

A measurement of the space-like pion electromagnetic form factor

International Nuclear Information System (INIS)

Amendolia, S.R.; Badelek, B.; Batignani, G.; Bedeschi, F.; Bertolucci, E.; Bettoni, D.; Bosisio, L.; Bradaschia, C.; Dell'Orso, M.; Fidecaro, F.; Foa, L.; Focardi, E.; Giazotto, A.; Giorgi, M.A.; Marrocchesi, P.S.; Menzione, A.; Ristori, L.; Scribano, A.; Tonelli, G.; Triggiani, G.; Codino, A.; Enorini, M.; Fabbri, F.L.; Laurelli, P.; Satta, L.; Spillantini, P.; Zallo, A.

1986-01-01

The pion form factor has been measured in the space-like q 2 region 0.014 to 0.26 (GeV/c) 2 by scattering 300 GeV pions from the electrons of a liquid hydrogen target. A detailed description is given of the apparatus, data analysis and corrections to the data. The mean square charge radius extracted from the data is model-dependent. We find that a form which includes a realistic description of the form factor phase gives a similar result to the naive pole form, and conclude π 2 >=0.439±0.008 fm 2 . (orig.)

Biogas Production from Brewer’s Yeast Using an Anaerobic Sequencing Batch Reactor

Directory of Open Access Journals (Sweden)

Gregor Drago Zupančič

2017-01-01

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

Molluscum-like lesions in a patient with sporotrichosis.

Science.gov (United States)

Schechtman, Regina Casz; Crignis, Giselly Silva Neto De; Pockstaller, Mercedes Prates; Azulay-Abulafia, Luna; Quintella, Leonardo Pereira; Belo, Márcia

2011-01-01

Sporotrichosis is a subcutaneous fungal infection caused by Sporothrix schenckii and acquired by direct inoculation. Although the majority of cases consist of the classic lymphocutaneous presentation, the frequency of atypical and severe clinical forms of the disease has increased progressively. Systemic and disseminated cutaneous sporotrichosis constitute rare variants and such cases are generally associated with cellular immunodeficiency or debilitated states. The present paper describes the first published case of molluscum-like lesions in disseminated mucocutaneous sporotrichosis. Direct mycological examination and histopathology revealed numerous yeast cells.

Comparative study on the freeze stability of yeast and chemical leavened steamed bread dough.

Science.gov (United States)

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

2017-04-15

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

Dietary glucose regulates yeast consumption in adult Drosophila males

Directory of Open Access Journals (Sweden)

Sebastien eLebreton

2014-12-01

Full Text Available The adjustment of feeding behavior in response to hunger and satiety contributes to homeostatic regulation in animals. The fruit fly Drosophila melanogaster feeds on yeasts growing on overripe fruit, providing nutrients required for adult survival, reproduction and larval growth. Here, we present data on how the nutritional value of food affects subsequent yeast consumption in Drosophila adult males. After a period of starvation, flies showed intensive yeast consumption. In comparison, flies stopped feeding after having access to a nutritive cornmeal diet. Interestingly, dietary glucose was equally efficient as the complex cornmeal diet. In contrast, flies fed with sucralose, a non-metabolizable sweetener, behaved as if they were starved. The adipokinetic hormone and insulin-like peptides regulate metabolic processes in insects. We did not find any effect of the adipokinetic hormone pathway on this modulation. Instead, the insulin pathway was involved in these changes. Flies lacking the insulin receptor did not respond to nutrient deprivation by increasing yeast consumption. Together these results show the importance of insulin in the regulation of yeast consumption in response to starvation in adult D. melanogaster males.

Transparent mediation-based access to multiple yeast data sources using an ontology driven interface.

Science.gov (United States)

Briache, Abdelaali; Marrakchi, Kamar; Kerzazi, Amine; Navas-Delgado, Ismael; Rossi Hassani, Badr D; Lairini, Khalid; Aldana-Montes, José F

2012-01-25

Saccharomyces cerevisiae is recognized as a model system representing a simple eukaryote whose genome can be easily manipulated. Information solicited by scientists on its biological entities (Proteins, Genes, RNAs...) is scattered within several data sources like SGD, Yeastract, CYGD-MIPS, BioGrid, PhosphoGrid, etc. Because of the heterogeneity of these sources, querying them separately and then manually combining the returned results is a complex and time-consuming task for biologists most of whom are not bioinformatics expert. It also reduces and limits the use that can be made on the available data. To provide transparent and simultaneous access to yeast sources, we have developed YeastMed: an XML and mediator-based system. In this paper, we present our approach in developing this system which takes advantage of SB-KOM to perform the query transformation needed and a set of Data Services to reach the integrated data sources. The system is composed of a set of modules that depend heavily on XML and Semantic Web technologies. User queries are expressed in terms of a domain ontology through a simple form-based web interface. YeastMed is the first mediation-based system specific for integrating yeast data sources. It was conceived mainly to help biologists to find simultaneously relevant data from multiple data sources. It has a biologist-friendly interface easy to use. The system is available at http://www.khaos.uma.es/yeastmed/.

Characterization and stability of lactobacilli and yeast microbiota in kefir grains.

Science.gov (United States)

Vardjan, T; Mohar Lorbeg, P; Rogelj, I; Čanžek Majhenič, A

2013-05-01

Characterization and stability of lactobacilli and yeasts from kefir grains using culture-dependent and culture-independent methods were investigated in this study. Culture-dependent analysis, followed by sequencing of 16S ribosomal DNA for bacteria and 26S rRNA gene for yeasts, revealed 3 different species of lactobacilli and yeasts, respectively. The most frequently isolated bacterial species were Lactobacillus kefiranofaciens ssp. kefirgranum, Lb. parakefiri, and Lb. kefiri, whereas yeasts belonged to Kluyveromyces marxianus, Kazachstania exigua, and Rhodosporidium kratochvilovae. This study is the first to report on the presence of R. kratochvilovae in kefir grains. On the other hand, PCR-denaturing gradient gel electrophoresis in the culture-independent method showed that the dominant microorganisms were Lb. kefiranofaciens ssp. kefirgranum, Kl. marxianus and Ka. exigua, but did not reveal bands corresponding to Lb. parakefiri, Lb. kefiri, or R. kratochvilovae. Our results support the necessity of combining more techniques for detailed and reliable study of microbial communities in kefir grains. Another interesting finding confirmed that the detected dominant microbiota of kefir grains is very stable and did not change over experimental time. This finding is important to ensure consistent product quality. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Sequestration of Sup35 by aggregates of huntingtin fragments causes toxicity of [PSI+] yeast.

Science.gov (United States)

Zhao, Xiaohong; Park, Yang-Nim; Todor, Horia; Moomau, Christine; Masison, Daniel; Eisenberg, Evan; Greene, Lois E

2012-07-06

Expression of huntingtin fragments with 103 glutamines (HttQ103) is toxic in yeast containing either the [PIN(+)] prion, which is the amyloid form of Rnq1, or [PSI(+)] prion, which is the amyloid form of Sup35. We find that HttQP103, which has a polyproline region at the C-terminal end of the polyQ repeat region, is significantly more toxic in [PSI(+)] yeast than in [PIN(+)], even though HttQP103 formed multiple aggregates in both [PSI(+)] and [PIN(+)] yeast. This toxicity was only observed in the strong [PSI(+)] variant, not the weak [PSI(+)] variant, which has more soluble Sup35 present than the strong variant. Furthermore, expression of the MC domains of Sup35, which retains the C-terminal domain of Sup35, but lacks the N-terminal prion domain, almost completely rescued HttQP103 toxicity, but was less effective in rescuing HttQ103 toxicity. Therefore, the toxicity of HttQP103 in yeast containing the [PSI(+)] prion is primarily due to sequestration of the essential protein, Sup35.

Downsides and benefits of unicellularity in budding yeast

Science.gov (United States)

Balazsi, Gabor; Chen, Lin; Kuzdzal-Fick, Jennie

Yeast cells that do not separate after cell division form clumps. Clumping was shown to aid utilization of certain sugars, but its effects in stressful conditions are unknown. Generally speaking, what are the costs and benefits of unicellularity versus clumping multicellularity in normal and stressful conditions? To address this question, we evolved clumping yeast towards unicellularity by continuously propagating only those cells that remain suspended in liquid culture after settling. Whole-genome sequencing indicated that mutations in the AMN1 (antagonist of mitotic exit network) gene underlie the changes from clumping to unicellular phenotypes in these evolved yeast cells. Simple models predict that clumping should hinder growth in normal conditions while being protective in stress. Accordingly, we find experimentally that yeast clumps are more resistant to freeze/thaw, hydrogen peroxide, and ethanol stressors than their unicellular counterparts. On the other hand, unicellularity seems to be advantageous in normal conditions. Overall, these results reveal the downsides and benefits of unicellularity in different environmental conditions and uncover its genetic bases in yeast. This research was supported by the NIH Director's New Innovator Award Program (1DP2 OD006481-01), by NSF/IOS 1021675 and the Laufer Center for Physical & Quantitative Biology.

Structural differences between yeast and mammalian microtubules revealed by cryo-EM

Energy Technology Data Exchange (ETDEWEB)

Howes, Stuart C. [Univ. of California, Berkeley, CA (United States). Biophysics Graduate Group; Geyer, Elisabeth A. [Univ. of Texas Southwestern Medical Center, Dallas, TX (United States). Dept. of Biophysics; Univ. of Texas Southwestern Medical Center, Dallas, TX (United States). Dept. of Biochemistry; LaFrance, Benjamin [Univ. of California, Berkeley, CA (United States). Molecular and Cell Biology Graduate Program; Zhang, Rui [Univ. of California, Berkeley, CA (United States). Howard Hughes Medical Inst.; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Biophysics and Integrated Bioimaging Division; Kellogg, Elizabeth H. [Univ. of California, Berkeley, CA (United States). Howard Hughes Medical Inst.; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Biophysics and Integrated Bioimaging Division; Westermann, Stefan [Univ. of Duisburg-Essen, Essen (Germany). Dept. of Molecular Genetics, Center for Medical Biotechnology; Rice, Luke M. [Univ. of Texas Southwestern Medical Center, Dallas, TX (United States). Dept. of Biophysics; Univ. of Texas Southwestern Medical Center, Dallas, TX (United States). Dept. of Biochemistry; Nogales, Eva [Univ. of California, Berkeley, CA (United States). Howard Hughes Medical Inst.; Univ. of California, Berkeley, CA (United States). Dept. of Molecular Biology and California Inst. for Quantitative Biosciences; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Biophysics and Integrated Bioimaging Division

2017-06-26

Microtubules are polymers of αβ-tubulin heterodimers essential for all eukaryotes. Despite sequence conservation, there are significant structural differences between microtubules assembled in vitro from mammalian or budding yeast tubulin. Yeast MTs were not observed to undergo compaction at the interdimer interface as seen for mammalian microtubules upon GTP hydrolysis. Lack of compaction might reflect slower GTP hydrolysis or a different degree of allosteric coupling in the lattice. The microtubule plus end–tracking protein Bim1 binds yeast microtubules both between αβ-tubulin heterodimers, as seen for other organisms, and within tubulin dimers, but binds mammalian tubulin only at interdimer contacts. At the concentrations used in cryo-electron microscopy, Bim1 causes the compaction of yeast microtubules and induces their rapid disassembly. In conclusion, our studies demonstrate structural differences between yeast and mammalian microtubules that likely underlie their differing polymerization dynamics. These differences may reflect adaptations to the demands of different cell size or range of physiological growth temperatures.

Reversion by calcium of a yeast-like development to the original filamentous form, of the 10V10 5-fluorocytosine-sensitive mutant of Aspergillus niger Reversão pelo cálcio de um desenvolvimento leveduriforme para a forma filamentosa original em um mutante sensível a 5-fluorocitosina na linhagem 10V10 de Aspergillus niger

Directory of Open Access Journals (Sweden)

Rosangela de Carvalho Goulart

2005-09-01

Full Text Available Some filamentous fungi present the phenomenon of dimorphism, their morphological structure alterations being capable of inducing metabolism changes. The Aspergillus niger strain 10v10, a producer of citric acid, was submitted to the mutagenic action of ultraviolet irradiation which respectively selects mutants sensitive or resistant to the antifungi agent 5 fluorocytosine (5-FC. 5-FC sensitive mutants presented a morphological alteration to a yeast-like form. The effects of pH changes, addition of salts (KH2PO4, NH4NO3, MgSO4 and MgCl2, the presence of osmotic stabilizers, as well as of calcium chloride, on morphological reversal and acid production were studied. Morphological reversal to the filamentous form was observed only in the presence of CaCl2 (500mM for the mutants strains 1 and 2, while the acid production occurred in both, yeast-like and filamentous forms.Alguns fungos filamentosos apresentam o fenômeno de dimorfismo, sendo que as alterações da estrutura morfológica podem induzir alterações metabólicas. A linhagem de Aspergillus niger 10v10, produtora de ácido cítrico foi submetida à ação mutagênica da radiação ultravioleta selecionando mutantes sensíveis ou resistentes ao antifúngico 5-fluorocitosina (5-FC. Os mutantes selecionados como sensíveis a 5-FC apresentaram uma alteração morfológica com desenvolvimento leveduriforme. Nestes mutantes foram avaliados o efeito da alteração de pH, a adição de sais (KH2PO4, NH4NO3, MgSO4e MnCl2, a presença de estabilizadores osmóticos, cloreto de cálcio, e o seu efeito sobre a reversão morfológica e a produção de ácido. A reversão morfológica para a forma filamentosa ocorreu apenas na presença de CaCl2 (500mM para as linhagens mutantes 1 e 2, enquanto que a produção de ácido ocorreu nas duas formas, leveduriforme e filamentosa.

Microfluidic screening and whole-genome sequencing identifies mutations associated with improved protein secretion by yeast

DEFF Research Database (Denmark)

Huang, Mingtao; Bai, Yunpeng; Sjostrom, Staffan L.

2015-01-01

There is an increasing demand for biotech-based production of recombinant proteins for use as pharmaceuticals in the food and feed industry and in industrial applications. Yeast Saccharomyces cerevisiae is among preferred cell factories for recombinant protein production, and there is increasing...... interest in improving its protein secretion capacity. Due to the complexity of the secretory machinery in eukaryotic cells, it is difficult to apply rational engineering for construction of improved strains. Here we used high-throughput microfluidics for the screening of yeast libraries, generated by UV...... mutagenesis. Several screening and sorting rounds resulted in the selection of eight yeast clones with significantly improved secretion of recombinant a-amylase. Efficient secretion was genetically stable in the selected clones. We performed whole-genome sequencing of the eight clones and identified 330...

Production of biopharmaceutical proteins by yeast: Advances through metabolic engineering

DEFF Research Database (Denmark)

Nielsen, Jens

2013-01-01

Production of recombinant proteins for use as pharmaceuticals, so-called biopharmaceuticals, is a multi-billion dollar industry. Many different cell factories are used for the production of biopharmaceuticals, but the yeast Saccharomyces cerevisiae is an important cell factory as it is used for p...... production. The involvement of directed metabolic engineering through the integration of tools from genetic engineering, systems biology and mathematical modeling, is also discussed....... by yeast are human serum albumin, hepatitis vaccines and virus like particles used for vaccination against human papillomavirus. Here is given a brief overview of biopharmaceutical production by yeast and it is discussed how the secretory pathway can be engineered to ensure more efficient protein...

Aging and differentiation in yeast populations: elders with different properties and functions.

Science.gov (United States)

Palková, Zdena; Wilkinson, Derek; Váchová, Libuše

2014-02-01

Over the past decade, it has become evident that similarly to cells forming metazoan tissues, yeast cells have the ability to differentiate and form specialized cell types. Examples of yeast cellular differentiation have been identified both in yeast liquid cultures and within multicellular structures occupying solid surfaces. Most current knowledge on different cell types comes from studies of the spatiotemporal internal architecture of colonies developing on various media. With a few exceptions, yeast cell differentiation often concerns nongrowing, stationary-phase cells and leads to the formation of cell subpopulations differing in stress resistance, cell metabolism, respiration, ROS production, and others. These differences can affect longevity of particular subpopulations. In contrast to liquid cultures, where various cell types are dispersed within stationary-phase populations, cellular differentiation depends on the specific position of particular cells within multicellular colonies. Differentiated colonies, thus, resemble primitive multicellular organisms, in which the gradients of certain compounds and the position of cells within the structure affect cellular differentiation. In this review, we summarize and compare the properties of diverse types of differentiated chronologically aging yeast cells that have been identified in colonies growing on different media, as well as of those found in liquid cultures. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Controlling Lipid Fluxes at Glycerol-3-phosphate Acyltransferase Step in Yeast

Science.gov (United States)

Marr, Nancy; Foglia, Julena; Terebiznik, Mauricio; Athenstaedt, Karin; Zaremberg, Vanina

2012-01-01

The ability to channel excess fatty acids into neutral lipids like triacylglycerol (TAG) is a critical strategy used by cells to maintain lipid homeostasis. Upon activation to acyl-CoA, fatty acids become readily available as substrates for acyltransferases involved in neutral lipid synthesis. Neutral lipids are then packed into organelles derived from the endoplasmic reticulum called lipid particles (LPs). The first acylation step in the de novo pathway for TAG synthesis is catalyzed by glycerol-3-phosphate acyltransferases (GPATs). Two isoforms, Gat1p/Gpt2p and Gat2p/Sct1p, are present in the yeast Saccharomyces cerevisiae. Previous evidence indicated that these enzymes contribute differentially to the synthesis of TAG in actively growing cells. In this work we studied the role of the yeast GPATs in the formation of LPs induced by a surplus of oleic acid. Yeast lacking Gat1p (but not Gat2p) were sensitive to oleate and failed to accumulate LPs induced by this unsaturated fatty acid. It is shown that oleate induces dephosphorylation of Gat1p as well as an increment in its levels. Most importantly, we identified novel Gat1p crescent structures that are formed in the presence of oleate. These structures are connected with the endoplasmic reticulum and are intimately associated with LPs. No such structures were observed for Gat2p. A crucial point of control of lipid fluxes at the GPAT step is proposed. PMID:22267742

Accumulation of gold using Baker's yeast, Saccharomyces cerevisiae

International Nuclear Information System (INIS)

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

Source and role of diacylglycerol formed during phagocytosis of opsonized yeast particles and associated respiratory burst in human neutrophils

International Nuclear Information System (INIS)

Della Bianca, V.; Grzeskowiak, M.; Lissandrini, D.; Rossi, F.

1991-01-01

The results presented in this paper demonstrate that in human neutrophils phagocytosis of C3b/bi and IgG-opsonized yeast particles is associated with activation of phospholipase D and that this reaction is the main source of diglycerides. The demonstration is based upon the following findings: (1) the challenge of neutrophils with these opsonized particles was followed by a rapid formation of [3H]alkyl-phosphatidic acid [( 3H]alkyl-PA) and [3H]alkyl-diglyceride [( 3H]alkyl-DG) in cells labeled with [3H]alkyl-lyso-phosphatidylcholine; (2) in the presence of ethanol [3H]alkyl-phosphatidylethanol was formed, and accumulation of [3H]alkyl-PA and [3H]alkyl-DG was depressed; (3) propranolol, by inhibiting the dephosphorylation of [3H]alkyl-PA, completely inhibited the accumulation of [3H]alkyl-DG and depressed by about 75% the formation of diglyceride mass. Evidence is also presented that phagocytosis of C3b/bi and IgG-opsonized yeast particles and associated respiratory burst can take place independently of diglyceride formation and of the activity of this second messenger on protein kinase C. In fact: (a) propranolol while completely inhibited the formation of diglyceride mass did not modify either the phagocytosis or respiratory burst; (b) these two processes were insensitive to staurosporine

Yeast genes involved in regulating cysteine uptake affect production of hydrogen sulfide from cysteine during fermentation.

Science.gov (United States)

Huang, Chien-Wei; Walker, Michelle E; Fedrizzi, Bruno; Gardner, Richard C; Jiranek, Vladimir

2017-08-01

An early burst of hydrogen sulfide (H2S) produced by Saccharomyces cerevisiae during fermentation could increase varietal thiols and therefore enhance desirable tropical aromas in varieties such as Sauvignon Blanc. Here we attempted to identify genes affecting H2S formation from cysteine by screening yeast deletion libraries via a colony colour assay on media resembling grape juice. Both Δlst4 and Δlst7 formed lighter coloured colonies and produced significantly less H2S than the wild type on high concentrations of cysteine, likely because they are unable to take up cysteine efficiently. We then examined the nine known cysteine permeases and found that deletion of AGP1, GNP1 and MUP1 led to reduced production of H2S from cysteine. We further showed that deleting genes involved in the SPS-sensing pathway such as STP1 and DAL81 also reduced H2S from cysteine. Together, this study indirectly confirms that Agp1p, Gnp1p and Mup1p are the major cysteine permeases and that they are regulated by the SPS-sensing and target of rapamycin pathways under the grape juice-like, cysteine-supplemented, fermentation conditions. The findings highlight that cysteine transportation could be a limiting factor for yeast to generate H2S from cysteine, and therefore selecting wine yeasts without defects in cysteine uptake could maximise thiol production potential. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Pro-region engineering for improved yeast display and secretion of brain derived neurotrophic factor.

Science.gov (United States)

Burns, Michael L; Malott, Thomas M; Metcalf, Kevin J; Puguh, Arthya; Chan, Jonah R; Shusta, Eric V

2016-03-01

Brain derived neurotrophic factor (BDNF) is a promising therapeutic candidate for a variety of neurological diseases. However, it is difficult to produce as a recombinant protein. In its native mammalian context, BDNF is first produced as a pro-protein with subsequent proteolytic removal of the pro-region to yield mature BDNF protein. Therefore, in an attempt to improve yeast as a host for heterologous BDNF production, the BDNF pro-region was first evaluated for its effects on BDNF surface display and secretion. Addition of the wild-type pro-region to yeast BDNF production constructs improved BDNF folding both as a surface-displayed and secreted protein in terms of binding its natural receptors TrkB and p75, but titers remained low. Looking to further enhance the chaperone-like functions provided by the pro-region, two rounds of directed evolution were performed, yielding mutated pro-regions that further improved the display and secretion properties of BDNF. Subsequent optimization of the protease recognition site was used to control whether the produced protein was in pro- or mature BDNF forms. Taken together, we have demonstrated an effective strategy for improving BDNF compatibility with yeast protein engineering and secretion platforms. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Size and competitive mating success in the yeast Saccharomyces cerevisiae.

Science.gov (United States)

Smith, Carl; Pomiankowski, Andrew; Greig, Duncan

2014-03-01

In unicellular organisms like yeast, mating with the right partner is critical to future fitness because each individual can only mate once. Because cell size is important for viability, mating with a partner of the right size could be a significant advantage. To investigate this idea, we manipulated the size of unmated yeast cells and showed that their viability depended on environmental conditions; large cells do better on rich medium and small cells do better on poor medium. We also found that the fitness of offspring is determined by the size of their parents. Finally, we demonstrated that when a focal cell of one mating type was placed with a large and a small cell of the opposite mating type, it was more likely to mate with the cell that was closer to the optimum size for growth in a given environment. This pattern was not generated by differences in passive mating efficiency of large and small cells across environments but by competitive mating behavior, mate preference, or both. We conclude that the most likely mechanism underlying this interesting behavior is that yeast cells compete for mates by producing pheromone signals advertising their viability, and cells with the opportunity to choose prefer to mate with stronger signalers because such matings produce more viable offspring.

Yeast for virus research

Science.gov (United States)

Zhao, Richard Yuqi

2017-01-01

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

Structural Studies of the Yeast Mitochondrial Degradosome

DEFF Research Database (Denmark)

Feddersen, Ane; Jonstrup, Anette Thyssen; Brodersen, Ditlev Egeskov

The yeast mitochondrial degradosome/exosome (mtExo) is responsible for most RNA turnover in mitochondria and has been proposed to form a central part of a mitochondrial RNA surveillance system responsible for degradation of aberrant and unprocessed RNA ([1], [2]). In contrast to the cytoplasmic...... and nuclear exosome complexes, which consist of 10-12 different nuclease subunits, the mitochondrial degradosome is composed of only two large subunits - an RNase (Dss1p) and a helicase (Suv3p), belonging the Ski2 class of DExH box RNA helicases. Both subunits are encoded on the yeast nuclear genome...... and and Suv3p from the fission yeast, Schizosaccharomyces pombe, have been cloned for heterologous expression in E. coli. Of the two, we have succeeded in purifying the 73kDa Suv3p by Ni2+-affinity chromatography followed by cleavage of the N-terminal His-tag, cation exchange, and gel filtration. Crystals...

Determination of Proteinaceous Selenocysteine in Selenized Yeast

Directory of Open Access Journals (Sweden)

Katarzyna Bierla

2018-02-01

Full Text Available A method for the quantitation of proteinaceous selenocysteine (SeCys in Se-rich yeast was developed. The method is based on the reduction of the Se-Se and S-Se bridges with dithiotretiol, derivatization with iodoacetamide (carbamidomethylation, followed by HPLC-ICP MS. The chromatographic conditions were optimized for the total recovery of the proteinaceous selenocysteine, the minimum number of peaks in the chromatogram (reduction of derivatization products of other Se-species present and the baseline separation. A typical chromatogram of a proteolytic digest of selenized yeast protein consisted of up to five peaks (including SeMet, carbamidomethylated (CAM-SeCys, and Se(CAM2 identified by retention time matching with available standards and electrospray MS. Inorganic selenium non-specifically attached to proteins and selenomethionine could be quantified (in the form of Se(CAM2 along with SeCys. Selenocysteine, selenomethionine, inorganic selenium, and the water soluble-metabolite fraction accounted for the totality of selenium species in Se-rich yeast.

Form-Stable Phase Change Materials Based on Eutectic Mixture of Tetradecanol and Fatty Acids for Building Energy Storage: Preparation and Performance Analysis

Directory of Open Access Journals (Sweden)

Yiran li

2013-10-01

Full Text Available This paper is focused on preparation and performance analysis of a series of form-stable phase change materials (FSPCMs, based on eutectic mixtures as phase change materials (PCMs for thermal energy storage and high-density polyethylene (HDPE-ethylene-vinyl acetate (EVA polymer as supporting materials. The PCMs were eutectic mixtures of tetradecanol (TD–capric acid (CA, TD–lauric acid (LA, and TD–myristic acid (MA, which were rarely explored before. Thermal properties of eutectic mixtures and FSPCMs were measured by differential scanning calorimeter (DSC. The onset melting/solidification temperatures of form-stable PCMs were 19.13 °C/13.32 °C (FS TD–CA PCM, 24.53 °C/24.92 °C (FS TD–LA PCM, and 33.15 °C/30.72 °C (FS TD–MA PCM, respectively, and latent heats were almost greater than 90 J/g. The surface morphologies and chemical stability of form-stable PCM were surveyed by scanning electron microscopy (SEM and Fourier-transform infrared (FT-IR spectroscopy, respectively. The thermal cycling test revealed that the thermal reliability of these three form-stable PCMs was good. Thermal storage/release experiment indicated melting/solidification time was shortened by introducing 10 wt % aluminum powder (AP. It is concluded that these FSPCMs can act as potential building thermal storage materials in terms of their satisfactory thermal properties.

Form-Stable Phase Change Materials Based on Eutectic Mixture of Tetradecanol and Fatty Acids for Building Energy Storage: Preparation and Performance Analysis.

Science.gov (United States)

Huang, Jingyu; Lu, Shilei; Kong, Xiangfei; Liu, Shangbao; Li, Yiran

2013-10-22

This paper is focused on preparation and performance analysis of a series of form-stable phase change materials (FSPCMs), based on eutectic mixtures as phase change materials (PCMs) for thermal energy storage and high-density polyethylene (HDPE)-ethylene-vinyl acetate (EVA) polymer as supporting materials. The PCMs were eutectic mixtures of tetradecanol (TD)-capric acid (CA), TD-lauric acid (LA), and TD-myristic acid (MA), which were rarely explored before. Thermal properties of eutectic mixtures and FSPCMs were measured by differential scanning calorimeter (DSC). The onset melting/solidification temperatures of form-stable PCMs were 19.13 °C/13.32 °C (FS TD-CA PCM), 24.53 °C/24.92 °C (FS TD-LA PCM), and 33.15 °C/30.72 °C (FS TD-MA PCM), respectively, and latent heats were almost greater than 90 J/g. The surface morphologies and chemical stability of form-stable PCM were surveyed by scanning electron microscopy (SEM) and Fourier-transform infrared (FT-IR) spectroscopy, respectively. The thermal cycling test revealed that the thermal reliability of these three form-stable PCMs was good. Thermal storage/release experiment indicated melting/solidification time was shortened by introducing 10 wt % aluminum powder (AP). It is concluded that these FSPCMs can act as potential building thermal storage materials in terms of their satisfactory thermal properties.

Catanionic mixtures forming gemini-like amphiphiles.

Science.gov (United States)

Sakai, Hideki; Okabe, Yuji; Tsuchiya, Koji; Sakai, Kenichi; Abe, Masahiko

2011-01-01

The properties of aqueous mixtures of cationic species with alkyl dicarboxylic acid compounds have been studied. The cationic compounds used in this study were tertiary amine-type N-methyl-N-(2,3-dioxypropyl)hexadecylamine (C16amine) and quaternary ammonium-type N,N-dimethyl-N-(2,3-dioxypropyl)hexadecylammonium chloride (C16Q). The alkyl dicarboxylic acid compounds used were HOOC(CH(2))(10)COOH (C12H) and its sodium salt (C12Na). Three aqueous mixtures were examined in this study: (System I) C16amine + C12H, (System II) C16Q + C12Na, and (System III) C16Q + C12H. The solution pH was set at 12 for System III. The combination of (1)H-NMR and mass spectroscopy data has suggested that a stoichiometric complex is formed in the aqueous solutions at a mole fraction of C12H (or C12Na) = 0.33. Here, the C12H (or C12Na) molecule added to the system bridges two cationic molecules, like a spacer of gemini surfactants. In fact, the static surface tensiometry has demonstrated that the stoichiometric complex behaves as gemini-like amphiphiles in aqueous solutions. Our current study offers a possible way for easily preparing gemini surfactant systems.

Engineering yeast metabolism for production of fuels and chemicals

DEFF Research Database (Denmark)

Nielsen, Jens

2016-01-01

faster development of metabolically engineered strains that can be used for production of fuels and chemicals. The yeast Saccharomyces cerevisiae is widely used for production of fuels, chemicals, pharmaceuticals and materials. Through metabolic engineering of this yeast a number of novel industrial...... as for metabolic design. In this lecture it will be demonstrated how the Design-Build-Test cycle of metabolic engineering has allowed for development of yeast cell factories for production of a range of different fuels and chemicals. Some examples of different technologies will be presented together with examples......Metabolic engineering relies on the Design-Build-Test cycle. This cycle includes technologies like mathematical modeling of metabolism, genome editing and advanced tools for phenotypic characterization. In recent years there have been advances in several of these technologies, which has enabled...

L-arabinose fermenting yeast

Science.gov (United States)

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

2013-02-12

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

Optimized protein extraction for quantitative proteomics of yeasts.

Directory of Open Access Journals (Sweden)

Tobias von der Haar

2007-10-01

Full Text Available The absolute quantification of intracellular protein levels is technically demanding, but has recently become more prominent because novel approaches like systems biology and metabolic control analysis require knowledge of these parameters. Current protocols for the extraction of proteins from yeast cells are likely to introduce artifacts into quantification procedures because of incomplete or selective extraction.We have developed a novel procedure for protein extraction from S. cerevisiae based on chemical lysis and simultaneous solubilization in SDS and urea, which can extract the great majority of proteins to apparent completeness. The procedure can be used for different Saccharomyces yeast species and varying growth conditions, is suitable for high-throughput extraction in a 96-well format, and the resulting extracts can easily be post-processed for use in non-SDS compatible procedures like 2D gel electrophoresis.An improved method for quantitative protein extraction has been developed that removes some of the sources of artefacts in quantitative proteomics experiments, while at the same time allowing novel types of applications.

Extracellular enzymatic activities and physiological profiles of yeasts colonizing fruit trees.

Science.gov (United States)

Molnárová, Jana; Vadkertiová, Renáta; Stratilová, Eva

2014-07-01

Yeasts form a significant and diverse part of the phyllosphere microbiota. Some yeasts that inhabit plants have been found to exhibit extracellular enzymatic activities. The aim of the present study was to investigate the ability of yeasts isolated from leaves, fruits, and blossoms of fruit trees cultivated in Southwest Slovakia to produce extracellular enzymes, and to discover whether the yeasts originating from these plant organs differ from each other in their physiological properties. In total, 92 strains belonging to 29 different species were tested for: extracellular protease, β-glucosidase, lipase, and polygalacturonase activities; fermentation abilities; the assimilation of xylose, saccharose and alcohols (methanol, ethanol, glycerol); and for growth in a medium with 33% glucose. The black yeast Aureobasidium pullulans showed the largest spectrum of activities of all the species tested. Almost 70% of the strains tested demonstrated some enzymatic activity, and more than 90% utilized one of the carbon compounds tested. Intraspecies variations were found for the species of the genera Cryptococcus and Pseudozyma. Interspecies differences of strains exhibiting some enzymatic activities and utilizing alcohols were also noted. The largest proportion of the yeasts exhibited β-glucosidase activity and assimilated alcohols independently of their origin. The highest number of strains positive for all activities tested was found among the yeasts associated with leaves. Yeasts isolated from blossoms assimilated saccharose and D-xylose the most frequently of all the yeasts tested. The majority of the fruit-inhabiting yeasts grew in the medium with higher osmotic pressure. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Science.gov (United States)

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

2014-08-20

This study was performed with the goal of revealing if the dehydration procedure used in our new immobilisation method noticeably decreases the viability of yeast cells in immobilised preparations. Various yeasts were used in this research: Saccharomyces cerevisiae cells that were rather sensitive to dehydration and had been aerobically grown in an ethanol-containing medium, a recombinant strain of S. cerevisiae grown in aerobic conditions which were completely non-resistant to dehydration and an anaerobically grown bakers' yeast strain S. cerevisiae, as well as a fairly resistant Pichia pastoris strain. Experiments performed showed that immobilisation of all these strains essentially increased their resistance to a dehydration-rehydration treatment. The increase of cells' viability (compared with control cells dehydrated in similar conditions) was from 30 to 60%. It is concluded that a new immobilisation method, which includes a dehydration stage, does not lead to an essential loss of yeast cell viability. Correspondingly, there is no risk of losing the biotechnological activities of immobilised preparations. The possibility of producing dry, active yeast preparations is shown, for those strains that are very sensitive to dehydration and which can be used in biotechnology in an immobilised form. Finally, the immobilisation approach can be used for the development of efficient methods for the storage of recombinant yeast strains. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthetic Biology and Metabolic Engineering Approaches and Its Impact on Non-Conventional Yeast and Biofuel Production

Energy Technology Data Exchange (ETDEWEB)

Madhavan, Aravind [Biotechnology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Trivandrum (India); Rajiv Gandhi Centre for Biotechnology, Trivandrum (India); Jose, Anju Alphonsa; Binod, Parameswaran; Sindhu, Raveendran, E-mail: sindhurgcb@gmail.com; Sukumaran, Rajeev K. [Biotechnology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Trivandrum (India); Pandey, Ashok [Biotechnology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Trivandrum (India); Center for Innovative and Applied Bioprocessing, Mohali, Punjab (India); Castro, Galliano Eulogio [Dpt. Ingeniería Química, Ambiental y de los Materiales Edificio, Universidad de Jaén, Jaén (Spain)

2017-04-25

The increasing fossil fuel scarcity has led to an urgent need to develop alternative fuels. Currently microorganisms have been extensively used for the production of first-generation biofuels from lignocellulosic biomass. Yeast is the efficient producer of bioethanol among all existing biofuels option. Tools of synthetic biology have revolutionized the field of microbial cell factories especially in the case of ethanol and fatty acid production. Most of the synthetic biology tools have been developed for the industrial workhorse Saccharomyces cerevisiae. The non-conventional yeast systems have several beneficial traits like ethanol tolerance, thermotolerance, inhibitor tolerance, genetic diversity, etc., and synthetic biology have the power to expand these traits. Currently, synthetic biology is slowly widening to the non-conventional yeasts like Hansenula polymorpha, Kluyveromyces lactis, Pichia pastoris, and Yarrowia lipolytica. Herein, we review the basic synthetic biology tools that can apply to non-conventional yeasts. Furthermore, we discuss the recent advances employed to develop efficient biofuel-producing non-conventional yeast strains by metabolic engineering and synthetic biology with recent examples. Looking forward, future synthetic engineering tools’ development and application should focus on unexplored non-conventional yeast species.

Synthetic Biology and Metabolic Engineering Approaches and Its Impact on Non-Conventional Yeast and Biofuel Production

Directory of Open Access Journals (Sweden)

Raveendran Sindhu

2017-04-01

Full Text Available The increasing fossil fuel scarcity has led to an urgent need to develop alternative fuels. Currently microorganisms have been extensively used for the production of first-generation biofuels from lignocellulosic biomass. Yeast is the efficient producer of bioethanol among all existing biofuels option. Tools of synthetic biology have revolutionized the field of microbial cell factories especially in the case of ethanol and fatty acid production. Most of the synthetic biology tools have been developed for the industrial workhorse Saccharomyces cerevisiae. The non-conventional yeast systems have several beneficial traits like ethanol tolerance, thermotolerance, inhibitor tolerance, genetic diversity, etc., and synthetic biology have the power to expand these traits. Currently, synthetic biology is slowly widening to the non-conventional yeasts like Hansenula polymorpha, Kluyveromyces lactis, Pichia pastoris, and Yarrowia lipolytica. Herein, we review the basic synthetic biology tools that can apply to non-conventional yeasts. Furthermore, we discuss the recent advances employed to develop efficient biofuel-producing non-conventional yeast strains by metabolic engineering and synthetic biology with recent examples. Looking forward, future synthetic engineering tools’ development and application should focus on unexplored non-conventional yeast species.

Synthetic Biology and Metabolic Engineering Approaches and Its Impact on Non-Conventional Yeast and Biofuel Production

International Nuclear Information System (INIS)

Madhavan, Aravind; Jose, Anju Alphonsa; Binod, Parameswaran; Sindhu, Raveendran; Sukumaran, Rajeev K.; Pandey, Ashok; Castro, Galliano Eulogio

2017-01-01

The increasing fossil fuel scarcity has led to an urgent need to develop alternative fuels. Currently microorganisms have been extensively used for the production of first-generation biofuels from lignocellulosic biomass. Yeast is the efficient producer of bioethanol among all existing biofuels option. Tools of synthetic biology have revolutionized the field of microbial cell factories especially in the case of ethanol and fatty acid production. Most of the synthetic biology tools have been developed for the industrial workhorse Saccharomyces cerevisiae. The non-conventional yeast systems have several beneficial traits like ethanol tolerance, thermotolerance, inhibitor tolerance, genetic diversity, etc., and synthetic biology have the power to expand these traits. Currently, synthetic biology is slowly widening to the non-conventional yeasts like Hansenula polymorpha, Kluyveromyces lactis, Pichia pastoris, and Yarrowia lipolytica. Herein, we review the basic synthetic biology tools that can apply to non-conventional yeasts. Furthermore, we discuss the recent advances employed to develop efficient biofuel-producing non-conventional yeast strains by metabolic engineering and synthetic biology with recent examples. Looking forward, future synthetic engineering tools’ development and application should focus on unexplored non-conventional yeast species.

Mitochondrial fission proteins regulate programmed cell death in yeast.

Science.gov (United States)

Fannjiang, Yihru; Cheng, Wen-Chih; Lee, Sarah J; Qi, Bing; Pevsner, Jonathan; McCaffery, J Michael; Hill, R Blake; Basañez, Gorka; Hardwick, J Marie

2004-11-15

The possibility that single-cell organisms undergo programmed cell death has been questioned in part because they lack several key components of the mammalian cell death machinery. However, yeast encode a homolog of human Drp1, a mitochondrial fission protein that was shown previously to promote mammalian cell death and the excessive mitochondrial fragmentation characteristic of apoptotic mammalian cells. In support of a primordial origin of programmed cell death involving mitochondria, we found that the Saccharomyces cerevisiae homolog of human Drp1, Dnm1, promotes mitochondrial fragmentation/degradation and cell death following treatment with several death stimuli. Two Dnm1-interacting factors also regulate yeast cell death. The WD40 repeat protein Mdv1/Net2 promotes cell death, consistent with its role in mitochondrial fission. In contrast to its fission function in healthy cells, Fis1 unexpectedly inhibits Dnm1-mediated mitochondrial fission and cysteine protease-dependent cell death in yeast. Furthermore, the ability of yeast Fis1 to inhibit mitochondrial fission and cell death can be functionally replaced by human Bcl-2 and Bcl-xL. Together, these findings indicate that yeast and mammalian cells have a conserved programmed death pathway regulated by a common molecular component, Drp1/Dnm1, that is inhibited by a Bcl-2-like function.

Influence of sodium chloride on wine yeast fermentation performance

Directory of Open Access Journals (Sweden)

Stilianos Logothetis

2010-06-01

Full Text Available Stilianos Logothetis1, Elias T Nerantzis2, Anna Gioulioti3, Tasos Kanelis2, Tataridis Panagiotis2, Graeme Walker11University of Abertay Dundee, School of Contemporary Sciences, Dundee, Scotland; 2TEI of Athens Department of Oenology and Spirit Technology, Biotechnology and Industrial Fermentations Lab Agiou Spiridonos, Athens, Greece; 3Ampeloiniki SA Industrial Park Thermi, Thessaloniki, GreeceAbstract: This paper concerns research into the influence of salt (sodium chloride on growth, viability and fermentation performance in a winemaking strain of the yeast, Saccharomyces cerevisiae. Experimental fermentations were conducted in both laboratory-scale and industrial-scale experiments. Preculturing yeasts in elevated levels of sodium chloride, or salt “preconditioning” led to improved fermentation performance. This was manifest by preconditioned yeasts having an improved capability to ferment high-sugar containing media with increased cell viability and with elevated levels of produced ethanol. Salt-preconditioning most likely influenced the stress-tolerance of yeasts by inducing the synthesis of key metabolites such as trehalose and glycerol. These compounds may act to improve cells’ ability to withstand osmostress and ethanol toxicity during fermentations of grape must. Industrial-scale trials using salt-preconditioned yeasts verified the benefit of this novel physiological cell engineering approach to practical winemaking fermentations.Keywords: salt, preconditioning, fermentation performance, Saccharomyces cerevisiae, wine

A study on the fundamental mechanism and the evolutionary driving forces behind aerobic fermentation in yeast.

Science.gov (United States)

Hagman, Arne; Piškur, Jure

2015-01-01

Baker's yeast Saccharomyces cerevisiae rapidly converts sugars to ethanol and carbon dioxide at both anaerobic and aerobic conditions. The later phenomenon is called Crabtree effect and has been described in two forms, long-term and short-term effect. We have previously studied under fully controlled aerobic conditions forty yeast species for their central carbon metabolism and the presence of long-term Crabtree effect. We have also studied ten steady-state yeast cultures, pulsed them with glucose, and followed the central carbon metabolism and the appearance of ethanol at dynamic conditions. In this paper we analyzed those wet laboratory data to elucidate possible mechanisms that determine the fate of glucose in different yeast species that cover approximately 250 million years of evolutionary history. We determine overflow metabolism to be the fundamental mechanism behind both long- and short-term Crabtree effect, which originated approximately 125-150 million years ago in the Saccharomyces lineage. The "invention" of overflow metabolism was the first step in the evolution of aerobic fermentation in yeast. It provides a general strategy to increase energy production rates, which we show is positively correlated to growth. The "invention" of overflow has also simultaneously enabled rapid glucose consumption in yeast, which is a trait that could have been selected for, to "starve" competitors in nature. We also show that glucose repression of respiration is confined mainly among S. cerevisiae and closely related species that diverged after the whole genome duplication event, less than 100 million years ago. Thus, glucose repression of respiration was apparently "invented" as a second step to further increase overflow and ethanol production, to inhibit growth of other microbes. The driving force behind the initial evolutionary steps was most likely competition with other microbes to faster consume and convert sugar into biomass, in niches that were semi-anaerobic.

A study on the fundamental mechanism and the evolutionary driving forces behind aerobic fermentation in yeast.

Directory of Open Access Journals (Sweden)

Arne Hagman

Full Text Available Baker's yeast Saccharomyces cerevisiae rapidly converts sugars to ethanol and carbon dioxide at both anaerobic and aerobic conditions. The later phenomenon is called Crabtree effect and has been described in two forms, long-term and short-term effect. We have previously studied under fully controlled aerobic conditions forty yeast species for their central carbon metabolism and the presence of long-term Crabtree effect. We have also studied ten steady-state yeast cultures, pulsed them with glucose, and followed the central carbon metabolism and the appearance of ethanol at dynamic conditions. In this paper we analyzed those wet laboratory data to elucidate possible mechanisms that determine the fate of glucose in different yeast species that cover approximately 250 million years of evolutionary history. We determine overflow metabolism to be the fundamental mechanism behind both long- and short-term Crabtree effect, which originated approximately 125-150 million years ago in the Saccharomyces lineage. The "invention" of overflow metabolism was the first step in the evolution of aerobic fermentation in yeast. It provides a general strategy to increase energy production rates, which we show is positively correlated to growth. The "invention" of overflow has also simultaneously enabled rapid glucose consumption in yeast, which is a trait that could have been selected for, to "starve" competitors in nature. We also show that glucose repression of respiration is confined mainly among S. cerevisiae and closely related species that diverged after the whole genome duplication event, less than 100 million years ago. Thus, glucose repression of respiration was apparently "invented" as a second step to further increase overflow and ethanol production, to inhibit growth of other microbes. The driving force behind the initial evolutionary steps was most likely competition with other microbes to faster consume and convert sugar into biomass, in niches that

In situ rheology of yeast biofilms.

Science.gov (United States)

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

2014-01-01

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

An organic solvent-, detergent-, and thermo-stable alkaline protease from the mesophilic, organic solvent-tolerant Bacillus licheniformis 3C5.

Science.gov (United States)

Rachadech, W; Navacharoen, A; Ruangsit, W; Pongtharangkul, T; Vangnai, A S

2010-01-01

Bacillus licheniformis 3C5, isolated as mesophilic bacterium, exhibited tolerance towards a wide range of non-polar and polar organic solvents at 45 degrees C. It produced an extracellular organic solvent-stable protease with an apparent molecular mass of approximately 32 kDa. The inhibitory effect of PMSF and EDTA suggested it is likely to be an alkaline serine protease. The protease was active over abroad range of temperatures (45-70 degrees C) and pH (8-10) range with an optimum activity at pH 10 and 65 degrees C. It was comparatively stable in the presence ofa relatively high concentration (35% (v/v)) of organic solvents and various types of detergents even at a relatively high temperature (45 degrees C). The protease production by B. licheniformis 3C5 was growth-dependent. The optimization of carbon and nitrogen sources for cell growth and protease production revealed that yeast extract was an important medium component to support both cell growth and the protease production. The overall properties of the protease produced by B. licheniformis 3C5 suggested that this thermo-stable, solvent-stable, detergent-stable alkaline protease is a promising potential biocatalyst for industrial and environmental applications.

Ndj1, a telomere-associated protein, regulates centrosome separation in budding yeast meiosis

Science.gov (United States)

Li, Ping; Shao, Yize; Jin, Hui

2015-01-01

Yeast centrosomes (called spindle pole bodies [SPBs]) remain cohesive for hours during meiotic G2 when recombination takes place. In contrast, SPBs separate within minutes after duplication in vegetative cells. We report here that Ndj1, a previously known meiosis-specific telomere-associated protein, is required for protecting SPB cohesion. Ndj1 localizes to the SPB but dissociates from it ∼16 min before SPB separation. Without Ndj1, meiotic SPBs lost cohesion prematurely, whereas overproduction of Ndj1 delayed SPB separation. When produced ectopically in vegetative cells, Ndj1 caused SPB separation defects and cell lethality. Localization of Ndj1 to the SPB depended on the SUN domain protein Mps3, and removal of the N terminus of Mps3 allowed SPB separation and suppressed the lethality of NDJ1-expressing vegetative cells. Finally, we show that Ndj1 forms oligomeric complexes with Mps3, and that the Polo-like kinase Cdc5 regulates Ndj1 protein stability and SPB separation. These findings reveal the underlying mechanism that coordinates yeast centrosome dynamics with meiotic telomere movement and cell cycle progression. PMID:25897084

Pentose utilization in yeasts: Physiology and biochemistry

Energy Technology Data Exchange (ETDEWEB)

Jeppson, H.

1996-04-01

The fermentive performance of bacteria, yeasts, and filamentous fungi was investigated in a pentose (xylose)-rich lignocellulosic hydrolyzate. The filamentous fungus Fusarium oxysporum and the xylose-fermenting yeast Pichia stipitis were found to be very sensitive to the inhibiting hydrolyzate. Recombinant xylose-utilizing Saccharomyces cerevisiae showed very poor ethanol formation from xylose; xylitol being the major product formed. The highest ethanol yields were obtained with recombinant Escherichia coli KO11, however, for maximal ethanol yield detoxification of the hydrolyzate was required. The influence of oxygen on the regulation of carbohydrate metabolism in the xylose-fermenting yeast P. stipitis CBS 6054 was investigated. A low and well-controlled level of oxygenation has been found to be required for efficient ethanol formation from xylose by the xylose-fermenting yeasts. The requirement of oxygen is frequently ascribed to the apparent redox imbalance which develops under anaerobic conditions due to the difference in co-factor utilization of the two first enzymes in the xylose metabolism, further reflected in xylitol excretion. However, a low and well controlled level of oxygenation for maximal ethanol production from glucose was also demonstrated, suggesting that the oxygen requirement is not only due to the dual co-factor utilization, but also serves other purposes. Cyanide-insensitive and salicyl hydroxamic acid-sensitive respiration (CIR) was found in P. stipitis. CIR is suggested to act as a redox sink preventing xylitol formation in P. stipitis under oxygen-limited xylose fermentations. Xylitol metabolism by P. stipitis CBS 6054 was strictly respiratory and ethanol was not formed under any conditions. The absence of ethanol formation was not due to a lack of fermentative enzymes, since the addition of glucose to xylitol-pregrown cells resulted in ethanol formation. 277 refs, 5 figs, 7 tabs

Serum albumin forms a lactoferrin-like soluble iron-binding complex in presence of hydrogen carbonate ions.

Science.gov (United States)

Ueno, Hiroshi M; Urazono, Hiroshi; Kobayashi, Toshiya

2014-02-15

The iron-lactoferrin complex is a common food ingredient because of its iron-solubilizing capability in the presence of hydrogen carbonate ions. However, it is unclear whether the formation of a stable iron-binding complex is limited to lactoferrin. In this study, we investigated the effects of bovine serum albumin (BSA) on iron solubility and iron-catalyzed lipid oxidation in the presence of hydrogen carbonate ions. BSA could solubilize >100-fold molar equivalents of iron at neutral pH, exceeding the specific metal-binding property of BSA. This iron-solubilizing capability of BSA was impaired by thermally denaturing BSA at ≥ 70 °C for 10 min at pH 8.5. The resulting iron-BSA complex inhibited iron-catalyzed oxidation of soybean oil in a water-in-oil emulsion measured using the Rancimat test. Our study is the first to show that BSA, like lactoferrin, forms a soluble iron-binding complex in the presence of hydrogen carbonate ions. Copyright © 2013 Elsevier Ltd. All rights reserved.

HDA2 and HDA3 are related proteins that interact with and are essential for the activity of the yeast histone deacetylase HDA1

OpenAIRE

Wu, Jiansheng; Carmen, Andrew A.; Kobayashi, Ryuji; Suka, Noriyuki; Grunstein, Michael

2001-01-01

Histone deacetylase HDA1, the prototype for the class II mammalian deacetylases, is likely the catalytic subunit of the HDA1-containing complex that is involved in TUP1-specific repression and global deacetylation in yeast. Although the class I RPD3-like enzymatic complexes have been well characterized, little is known about the identity and interactions of the factors that associate to form the HDA1 complex. In this paper, we identify related HDA2 and HDA3 proteins that ...

Yeast vitality during cider fermentation: assessment by energy metabolism.

Science.gov (United States)

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

1999-03-15

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

Preparation, thermal and flammability properties of a novel form-stable phase change materials based on high density polyethylene/poly(ethylene-co-vinyl acetate)/organophilic montmorillonite nanocomposites/paraffin compounds

International Nuclear Information System (INIS)

Cai Yibing; Song Lei; He Qingliang; Yang Dandan; Hu Yuan

2008-01-01

The paraffin is one of important thermal energy storage materials with many desirable characteristics (i.e., high heat of fusion, varied phase change temperature, negligible supercooling, self-nucleating, no phase segregation and cheap, etc.), but has low thermal stability and flammable. Hence, a novel form-stable phase change materials (PCM) based on high density polyethylene (HDPE)/poly(ethylene-co-vinyl acetate) (EVA)/organophilic montmorillonite (OMT) nanocomposites and paraffin are prepared by twin-screw extruder technique. The structures of the HDPE-EVA/OMT nanocomposites and the form-stable PCM are evidenced by the X-ray diffraction (XRD), transmission electronic microscopy (TEM) and scanning electronic microscope (SEM). The results of XRD and TEM show that the HDPE-EVA/OMT nanocomposites form the ordered intercalated nanomorphology. The form-stable PCM consists of the paraffin, which acts as a dispersed phase change material and the HDPE-EVA/OMT nanocomposites, which acts as the supporting material. The paraffin disperses in the three-dimensional net structure formed by HDPE-EVA/OMT nanocomposites. The thermal stability, latent heat and flammability properties are characterized by thermogravimetry analysis (TGA), dynamic Fourier-transform infrared (FTIR), differential scanning calorimeter (DSC) and cone calorimeter, respectively. The TGA and dynamic FTIR analyses indicate that the incorporation of suitable amount of OMT into the form-stable PCM increase the thermal stability. The DSC results show that the latent heat of the form-stable PCM has a certain degree decrease. The cone calorimeter shows that the heat release rate (HRR) has remarkably decreases with loading of OMT in the form-stable PCM, contributing to the improved flammability properties

Yeast Flocculation—Sedimentation and Flotation

Directory of Open Access Journals (Sweden)

Graham G. Stewart

2018-04-01

Full Text Available Unlike most fermentation alcohol beverage production processes, brewers recycle their yeast. This is achieved by employing a yeast culture’s: flocculation, adhesion, sedimentation, flotation, and cropping characteristics. As a consequence of yeast recycling, the quality of the cropped yeast culture’s characteristics is critical. However, the other major function of brewer’s yeast is to metabolise wort into ethanol, carbon dioxide, glycerol, and other fermentation products, many of which contribute to beer’s overall flavour characteristics. This review will only focus on brewer’s yeast flocculation characteristics.

L-arabinose fermenting yeast

Science.gov (United States)

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

2010-12-07

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

The stable nonequilibrium state of bicarbonate aqueous systems

Science.gov (United States)

Voeikov, V. L.; Vilenskaya, N. D.; Ha, Do Minh; Malyshenko, S. I.; Buravleva, E. V.; Yablonskaya, O. I.; Timofeev, K. N.

2012-09-01

Data obtained by electron paramagnetic resonance (EPR) and chemiluminescence analysis indicate that in aqueous solutions of bicarbonates, superoxide radical and other reactive oxygen species (ROS) are constantly produced. The stationary level of the superoxide radical is found to increase when a solution is illuminated. Reactions involving ROS are shown to be accompanied by the generation of electron excitation energy, keeping bicarbonate solutions in a stable nonequilibrium state. The system can emit part of this energy. Variations in emitting activity are found to correlate with variations in the cosmophysical factors. The emitting activity of solutions is found to vary in the presence of low and ultralow concentrations of hydrated fullerenes. It is noted that the phenomenon of spontaneous charge separation in aqueous systems (G. H. Pollack) could play a role in maintaining a stable nonequilibrium state in bicarbonate systems where the reactions with ROS participation are catalyzed by forms of carbonate. It is concluded that the abovementioned properties of bicarbonate aqueous systems most likely keep living matter whose structural basis is formed by these systems in a stable excited state, thereby making it highly sensitive to the action of external factors with low and ultralow intensities.

Culturable yeasts in meltwaters draining from two glaciers in the Italian Alps

Science.gov (United States)

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

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

Drosophila Regulate Yeast Density and Increase Yeast Community Similarity in a Natural Substrate

OpenAIRE

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

2012-01-01

Drosophila melanogaster adults and larvae, but especially larvae, had profound effects on the densities and community structure of yeasts that developed in banana fruits. Pieces of fruit exposed to adult female flies previously fed fly-conditioned bananas developed higher yeast densities than pieces of the same fruits that were not exposed to flies, supporting previous suggestions that adult Drosophila vector yeasts to new substrates. However, larvae alone had dramatic effects on yeast densit...

Distribution of dimorphic yeast species in commercial extra virgin olive oil.

Science.gov (United States)

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

2010-12-01

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

Detection of amastigote-like forms in the valve of Phlebotomus papatasi infected with Leishmania major

Directory of Open Access Journals (Sweden)

Nestor Añez

2003-06-01

Full Text Available A massive and homogeneous amount of amastigote-like forms was detected in the stomodeal valve (SV and the thoracic mid-gut (TMG of Leishmania major-infected Phlebotomus papatasi, which received a second blood meal 13 to 21 days post-infection on healthy anaesthetized hamsters. After re-feeding, the infected sand flies were dissected out to examine the morphology of the parasite in SV, TMG and the abdominal mid-gut (AMG. Different promastigote forms were seen in the infected flies. Among these included typical promastigotes (nectomonads and haptomonads, paramastigotes, metacyclic promastigotes and, in some samples, the here-reported amastigote-like forms. The Leishmania amastigote-like forms were detected in the SV of sand flies with 14, 18 and 21 days of infection as well as in the TMG at 13 and 18 days post-infection. However, the amastigote-like forms were not detected in the AMG. Factors such as the acidic pH predominating the TMG and the SV, as well as the temperature of the ingested blood, among others, are suggested as contributing to the transformation of the typical promastigotes into the amastigote-like forms. The significance of this finding is discussed and the possible biological advantage for transmission of Leishmania is considered.

Checkpoint independence of most DNA replication origins in fission yeast.

Science.gov (United States)

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

2007-12-19

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

Checkpoint independence of most DNA replication origins in fission yeast

Science.gov (United States)

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

2007-01-01

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

Checkpoint independence of most DNA replication origins in fission yeast

Directory of Open Access Journals (Sweden)

Scott Donna

2007-12-01

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

Interaction of human laminin receptor with Sup35, the [PSI⁺] prion-forming protein from S. cerevisiae: a yeast model for studies of LamR interactions with amyloidogenic proteins.

Directory of Open Access Journals (Sweden)

Christine Pampeno

Full Text Available The laminin receptor (LamR is a cell surface receptor for extracellular matrix laminin, whereas the same protein within the cell interacts with ribosomes, nuclear proteins and cytoskeletal fibers. LamR has been shown to be a receptor for several bacteria and viruses. Furthermore, LamR interacts with both cellular and infectious forms of the prion protein, PrP(C and PrP(Sc. Indeed, LamR is a receptor for PrP(C. Whether LamR interacts with PrP(Sc exclusively in a capacity of the PrP receptor, or LamR specifically recognizes prion determinants of PrP(Sc, is unclear. In order to explore whether LamR has a propensity to interact with prions and amyloids, we examined LamR interaction with the yeast prion-forming protein, Sup35. Sup35 is a translation termination factor with no homology or functional relationship to PrP. Plasmids expressing LamR or LamR fused with the green fluorescent protein (GFP were transformed into yeast strain variants differing by the presence or absence of the prion conformation of Sup35, respectively [PSI⁺] and [psi⁻]. Analyses by immunoprecipitation, centrifugal fractionation and fluorescent microscopy reveal interaction between LamR and Sup35 in [PSI⁺] strains. The presence of [PSI⁺] promotes LamR co-precipitation with Sup35 as well as LamR aggregation. In [PSI⁺] cells, LamR tagged with GFP or mCherry forms bright fluorescent aggregates that co-localize with visible [PSI⁺] foci. The yeast prion model will facilitate studying the interaction of LamR with amyloidogenic prions in a safe and easily manipulated system that may lead to a better understanding and treatment of amyloid diseases.

Cystobasidiomycetes yeasts from Patagonia (Argentina): description of Rhodotorula meli sp. nov. from glacial meltwater.

Science.gov (United States)

Libkind, Diego; Sampaio, José Paulo; van Broock, Maria

2010-09-01

A basidiomycetous yeast, strain CRUB 1032(T), which formed salmon-pink colonies, was isolated from glacial meltwater in Patagonia, Argentina. Morphological, physiological and biochemical characterization indicated that this strain belonged to the genus Rhodotorula. Molecular taxonomic analysis based on the 26S rDNA D1/D2 domain and internal transcribed spacer region sequences showed that strain CRUB 1032(T) represents an undescribed yeast species, for which the name Rhodotorula meli sp. nov. is proposed (type strain is CRUB 1032(T)=CBS 10797(T)=JCM 15319(T)). Phylogenetic analysis showed that Rhodotorula lamellibrachii was the closest known species, which, together with R. meli, formed a separate cluster related to the Sakaguchia clade within the Cystobasidiomycetes. Additional Patagonian yeast isolates of the class Cystobasidiomycetes are also investigated in the present work.

In vitro attachment of phylloplane yeasts to Botrytis cinerea, Rhizoctonia solani, and Sclerotinia homoeocarpa.

Science.gov (United States)

Allen, Tom W; Burpee, Leon L; Buck, James W

2004-12-01

The ability of yeasts to attach to hyphae or conidia of phytopathogenic fungi has been speculated to contribute to biocontrol activity on plant surfaces. Attachment of phylloplane yeasts to Botrytis cinerea, Rhizoctonia solani, and Sclerotinia homoeocarpa was determined using in vitro attachment assays. Yeasts were incubated for 2 d on potato dextrose agar (PDA) prior to experimentation. A total of 292 yeasts cultured on PDA were screened for their ability to attach to conidia of B. cinerea; 260 isolates (89.1%) attached to conidia forming large aggregates of cells, and 22 isolates (7.5%) weakly attached to conidia with 1 or 2 yeast cells attached to a few conidia. Ten yeasts (3.4%), including 8 isolates of Cryptococcus laurentii, 1 isolate of Cryptococcus flavescens, and an unidentified species of Cryptococcus, failed to attach to conidia. All non-attaching yeasts produced copious extracellular polysaccharide (EPS) on PDA. Seventeen yeast isolates did not attach to hyphal fragments of B. cinerea, R. solani, and S. homoeocarpa after a 1 h incubation, but attachment was observed after 24 h. Culture medium, but not culture age, significantly affected the attachment of yeast cells to conidia of B. cinerea. The 10 yeast isolates that did not attach to conidia when grown on agar did attach to conidia (20%-57% of conidia with attached yeast cells) when cultured in liquid medium. Attachment of the biocontrol yeast Rhodotorula glutinis PM4 to conidia of B. cinerea was significantly greater at 1 x 10(7) yeast cells x mL(-1) than at lower concentrations of yeast cells. The ability of yeast cells to attach to fungal conidia or hyphae appears to be a common phenotype among phylloplane yeasts.

Lipidomics in research on yeast membrane lipid homeostasis.

Science.gov (United States)

de Kroon, Anton I P M

2017-08-01

Mass spectrometry is increasingly used in research on membrane lipid homeostasis, both in analyses of the steady state lipidome at the level of molecular lipid species, and in pulse-chase approaches employing stable isotope-labeled lipid precursors addressing the dynamics of lipid metabolism. Here my experience with, and view on mass spectrometry-based lipid analysis is presented, with emphasis on aspects of quantification of membrane lipid composition of the yeast Saccharomyces cerevisiae. This article is part of a Special Issue entitled: BBALIP_Lipidomics Opinion Articles edited by Sepp Kohlwein. Copyright © 2017 Elsevier B.V. All rights reserved.

Yeast strains designed for 2. generation bioethanol production. Final report

Energy Technology Data Exchange (ETDEWEB)

Roennow, B.

2013-04-15

The aim of the project was to develop a suitable fermentation organism for 2G bioethanol production that would efficiently ferment all of the sugars in lignocellulosic biomass into ethanol at a commercially viable rate (comparable to yeast based 1G ethanol production). More specifically, a yeast strain would be developed with the ability to ferment also the pentoses in lignocellulosic biomass and thereby increase the ethanol yield of the process by 30-45% with a profound positive effect on the total process economy. The project has succeeded in developing a new industrial yeast strain V1. The yeast strain can transform the difficult C5 sugars to ethanol from waste products such as straw and the like from the agricultural sector. The classic issues relating to industrial uses such as inhibitor and ethanol tolerance and high ethanol production is resolved satisfactorily. The potential of the use of the new strain for 2nd generation bioethanol production is that the ethanol yields increase by 30-45%. With the increased ethanol yield follows a marked improvement in the overall process economics. (LN)

New yeasts-new brews: modern approaches to brewing yeast design and development.

Science.gov (United States)

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

2017-06-01

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

Simultaneous saccharification and fermentation (SSF) using cellobiose fermenting yeast Brettanomyces custersii

Science.gov (United States)

Spindler, Diane D.; Grohmann, Karel; Wyman, Charles E.

1992-01-01

A process for producing ethanol from plant biomass includes forming a substrate from the biomass with the substrate including hydrolysates of cellulose and hemicellulose. A species of the yeast Brettanomyces custersii (CBS 5512), which has the ability to ferment both cellobiose and glucose to ethanol, is then selected and isolated. The substrate is inoculated with this yeast, and the inoculated substrate is then fermented under conditions favorable for cell viability and conversion of hydrolysates to ethanol.

Vaginal yeast infection

Science.gov (United States)

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

Membrane-sculpting BAR domains generate stable lipid microdomains

DEFF Research Database (Denmark)

Zhao, Hongxia; Michelot, Alphée; Koskela, Essi V.

2013-01-01

Bin-Amphiphysin-Rvs (BAR) domain proteins are central regulators of many cellular processes involving membrane dynamics. BAR domains sculpt phosphoinositide-rich membranes to generate membrane protrusions or invaginations. Here, we report that, in addition to regulating membrane geometry, BAR...... domains can generate extremely stable lipid microdomains by "freezing" phosphoinositide dynamics. This is a general feature of BAR domains, because the yeast endocytic BAR and Fes/CIP4 homology BAR (F-BAR) domains, the inverse BAR domain of Pinkbar, and the eisosomal BAR protein Lsp1 induced...... phosphoinositide clustering and halted lipid diffusion, despite differences in mechanisms of membrane interactions. Lsp1 displays comparable low diffusion rates in vitro and in vivo, suggesting that BAR domain proteins also generate stable phosphoinositide microdomains in cells. These results uncover a conserved...

Characterization of volatile fraction of typical Irpinian wines fermented with a new starter yeast.

Science.gov (United States)

Calabretti, A; La Cara, F; Sorrentino, A; Di Stasio, M; Santomauro, F; Rastrelli, L; Gabrielli, L; Limone, F; Volpe, M G

2012-04-01

Non-Saccharomyces yeasts are microorganisms that play an important role in the fermentation dynamics, compositions and flavour of wine. The aromatic compounds responsible for varietal aroma in wine are mainly terpenes, of which the most important group are the monoterpenes because of their volatility and odour if present in a free form. In fact, some terpenyl-glycosides do not contribute to the aroma unless they are hydrolysed. The glycosylated form of terpenes can be converted by hydrolysis with β-glycosidases produced by yeasts during the winemaking process, into aromatic compounds. In this study we utilized a non-Saccharomyces yeast, with a high extra-cellular glycosidase activity, isolated from grapes of cultivars typical of Irpinia region. This strain, identified as a Rhodotorula mucillaginosa (strain WLR12), was used to carry out an experimental winemaking process and the results were compared with those obtained with a commercial yeast starter. Chemical and sensorial analysis demonstrated that the wines produced with WLR12 strain had a more floral aroma and some sweet and ripened fruit notes compared to those obtained with commercial yeast. The data also showed an increasing of the free terpenes fraction that, however, did not significatively modify the bouquet of the wines.

Spent yeast as natural source of functional food additives

Science.gov (United States)

Rakowska, Rita; Sadowska, Anna; Dybkowska, Ewa; Świderski, Franciszek

Spent yeasts are by-products arising from beer and wine production which over many years have been chiefly used as feed additives for livestock. They contain many valuable and bioactive substances which has thereby generated much interest in their exploitation. Up till now, the main products obtained from beer-brewing yeasts are β-glucans and yeast extracts. Other like foodstuffs include dried brewer’s yeast, where this is dried and the bitterness removed to be fit for human consumption as well as mannan-oligosaccharides hitherto used in the feed industry. β-glucans constitute the building blocks of yeast cell walls and can thus be used in human nutrition as dietary supplements or serving as food additives in functional foods. β-glucans products obtained via post-fermentation of beer also exhibit a high and multi-faceted biological activity where they improve the blood’s lipid profile, enhance immunological status and have both prebiotic and anti-oxidant properties. Yeast extracts are currently being used more and more to enhance flavour in foodstuffs, particularly for meat and its products. Depending on how autolysis is carried out, it is possible to design extracts of various meat flavours characteristic of specific meats. Many different flavour profiles can be created which may be additionally increased in combination with vegetable extracts. Within the food market, yeast extracts can appear in various guises such as liquids, pastes or powders. They all contain significant amounts of glutamic acid, 5’-GMP and 5’-IMP nucleotides together with various amino acids and peptides that act synergistically for enhancing the flavour of foodstuff products. Recent studies have demonstrated additional benefits of yeast extracts as valuable sources of amino acids and peptides which can be used in functional foods and dietary supplements. These products possess GRAS status (Generally Recognised As Safe) which thereby also adds further as to why they should be used

Selection and Characterization of Potential Baker's Yeast from Indigenous Resources of Nepal.

Science.gov (United States)

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

2017-01-01

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

Brewing characteristics of haploid strains isolated from sake yeast Kyokai No. 7.

Science.gov (United States)

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

2008-11-01

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

Kazachstania gamospora and Wickerhamomyces subpelliculosus: Two alternative baker's yeasts in the modern bakery.

Science.gov (United States)

Zhou, Nerve; Schifferdecker, Anna Judith; Gamero, Amparo; Compagno, Concetta; Boekhout, Teun; Piškur, Jure; Knecht, Wolfgang

2017-06-05

Saccharomyces cerevisiae, the conventional baker's yeast, remains the most domesticated yeast monopolizing the baking industry. Its rapid consumption of sugars and production of CO 2 are the most important attributes required to leaven the dough. New research attempts highlight that these attributes are not unique to S. cerevisiae, but also found in several non-conventional yeast species. A small number of these yeast species with similar properties have been described, but remain poorly studied. They present a vast untapped potential for the use as leavening agents and flavor producers due to their genetic and phylogenetic diversity. We assessed the potential of several non-conventional yeasts as leavening agents and flavor producers in dough-like conditions in the presence of high sugar concentrations and stressful environments mimicking conditions found in flour dough. We tested the capabilities of bread leavening and aroma formation in a microbread platform as well as in a bakery setup. Bread leavened with Kazachstania gamospora and Wickerhamomyces subpelliculosus had better overall results compared to control baker's yeast. In addition, both displayed higher stress tolerance and broader aroma profiles than the control baker's yeast. These attributes are important in bread and other farinaceous products, making K. gamospora and W. subpelliculosus highly applicable as alternative baker's yeasts. Copyright © 2017 Elsevier B.V. All rights reserved.

Broken Homes: Stable Risk, Changing Reasons, Changing Forms.

Science.gov (United States)

Sweetser, Dorrian Apple

1985-01-01

Cohort membership and two measures of social disadvantage were used as explanatory variables in analysis of the risk of growing up in a broken home and of the living arrangements of children with broken homes. The risk of a broken home by age 16 proved to be stable across cohorts and greater for those from disadvantaged homes. (Author/BL)

Correlation of Meiotic DSB Formation and Transcription Initiation Around Fission Yeast Recombination Hotspots.

Science.gov (United States)

Yamada, Shintaro; Okamura, Mika; Oda, Arisa; Murakami, Hiroshi; Ohta, Kunihiro; Yamada, Takatomi

2017-06-01

Meiotic homologous recombination, a critical event for ensuring faithful chromosome segregation and creating genetic diversity, is initiated by programmed DNA double-strand breaks (DSBs) formed at recombination hotspots. Meiotic DSB formation is likely to be influenced by other DNA-templated processes including transcription, but how DSB formation and transcription interact with each other has not been understood well. In this study, we used fission yeast to investigate a possible interplay of these two events. A group of hotspots in fission yeast are associated with sequences similar to the cyclic AMP response element and activated by the ATF/CREB family transcription factor dimer Atf1-Pcr1. We first focused on one of those hotspots, ade6-3049 , and Atf1. Our results showed that multiple transcripts, shorter than the ade6 full-length messenger RNA, emanate from a region surrounding the ade6-3049 hotspot. Interestingly, we found that the previously known recombination-activation region of Atf1 is also a transactivation domain, whose deletion affected DSB formation and short transcript production at ade6-3049 These results point to a possibility that the two events may be related to each other at ade6-3049 In fact, comparison of published maps of meiotic transcripts and hotspots suggested that hotspots are very often located close to meiotically transcribed regions. These observations therefore propose that meiotic DSB formation in fission yeast may be connected to transcription of surrounding regions. Copyright © 2017 by the Genetics Society of America.

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

Science.gov (United States)

Niki, Hironori

2014-03-01

The clade of Schizosaccharomyces includes 4 species: S. pombe, S. octosporus, S. cryophilus, and S. japonicus. Although all 4 species exhibit unicellular growth with a binary fission mode of cell division, S. japonicus alone is dimorphic yeast, which can transit from unicellular yeast to long filamentous hyphae. Recently it was found that the hyphal cells response to light and then synchronously activate cytokinesis of hyphae. In addition to hyphal growth, S. japonicas has many properties that aren't shared with other fission yeast. Mitosis of S. japonicas is referred to as semi-open mitosis because dynamics of nuclear membrane is an intermediate mode between open mitosis and closed mitosis. Novel genetic tools and the whole genomic sequencing of S. japonicas now provide us with an opportunity for revealing unique characters of the dimorphic yeast. © 2013 The Author. Yeast Published by John Wiley & Sons Ltd.

Understanding start-up problems in yeast glycolysis.

Science.gov (United States)

Overal, Gosse B; Teusink, Bas; Bruggeman, Frank J; Hulshof, Josephus; Planqué, Robert

2018-05-01

Yeast glycolysis has been the focus of research for decades, yet a number of dynamical aspects of yeast glycolysis remain poorly understood at present. If nutrients are scarce, yeast will provide its catabolic and energetic needs with other pathways, but the enzymes catalysing upper glycolytic fluxes are still expressed. We conjecture that this overexpression facilitates the rapid transition to glycolysis in case of a sudden increase in nutrient concentration. However, if starved yeast is presented with abundant glucose, it can enter into an imbalanced state where glycolytic intermediates keep accumulating, leading to arrested growth and cell death. The bistability between regularly functioning and imbalanced phenotypes has been shown to depend on redox balance. We shed new light on these phenomena with a mathematical analysis of an ordinary differential equation model, including NADH to account for the redox balance. In order to gain qualitative insight, most of the analysis is parameter-free, i.e., without assigning a numerical value to any of the parameters. The model has a subtle bifurcation at the switch between an inviable equilibrium state and stable flux through glycolysis. This switch occurs if the ratio between the flux through upper glycolysis and ATP consumption rate of the cell exceeds a fixed threshold. If the enzymes of upper glycolysis would be barely expressed, our model predicts that there will be no glycolytic flux, even if external glucose would be at growth-permissable levels. The existence of the imbalanced state can be found for certain parameter conditions independent of the mentioned bifurcation. The parameter-free analysis proved too complex to directly gain insight into the imbalanced states, but the starting point of a branch of imbalanced states can be shown to exist in detail. Moreover, the analysis offers the key ingredients necessary for successful numerical continuation, which highlight the existence of this bistability and the

Yeast surface displaying glucose oxidase as whole-cell biocatalyst: construction, characterization, and its electrochemical glucose sensing application.

Science.gov (United States)

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

2013-06-18

The display of glucose oxidase (GOx) on yeast cell surface using a-agglutinin as an anchor motif was successfully developed. Both the immunochemical analysis and enzymatic assay showed that active GOx was efficiently expressed and translocated on the cell surface. Compared with conventional GOx, the yeast cell surface that displayed GOx (GOx-yeast) demonstrated excellent enzyme properties, such as good stability within a wide pH range (pH 3.5-11.5), good thermostability (retaining over 94.8% enzyme activity at 52 °C and 84.2% enzyme activity at 56 °C), and high d-glucose specificity. In addition, direct electrochemistry was achieved at a GOx-yeast/multiwalled-carbon-nanotube modified electrode, suggesting that the host cell of yeast did not have any adverse effect on the electrocatalytic property of the recombinant GOx. Thus, a novel electrochemical glucose biosensor based on this GOx-yeast was developed. The as-prepared biosensor was linear with the concentration of d-glucose within the range of 0.1-14 mM and a low detection limit of 0.05 mM (signal-to-noise ratio of S/N = 3). Moreover, the as-prepared biosensor is stable, specific, reproducible, simple, and cost-effective, which can be applicable for real sample detection. The proposed strategy to construct robust GOx-yeast may be applied to explore other oxidase-displaying-system-based whole-cell biocatalysts, which can find broad potential application in biosensors, bioenergy, and industrial catalysis.

Saccharomyces cerevisiae: a sexy yeast with a prion problem.

Science.gov (United States)

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.

Insight on an arginine synthesis metabolon from the tetrameric structure of yeast acetylglutamate kinase.

Science.gov (United States)

de Cima, Sergio; Gil-Ortiz, Fernando; Crabeel, Marjolaine; Fita, Ignacio; Rubio, Vicente

2012-01-01

N-acetyl-L-glutamate kinase (NAGK) catalyzes the second, generally controlling, step of arginine biosynthesis. In yeasts, NAGK exists either alone or forming a metabolon with N-acetyl-L-glutamate synthase (NAGS), which catalyzes the first step and exists only within the metabolon. Yeast NAGK (yNAGK) has, in addition to the amino acid kinase (AAK) domain found in other NAGKs, a ~150-residue C-terminal domain of unclear significance belonging to the DUF619 domain family. We deleted this domain, proving that it stabilizes yNAGK, slows catalysis and modulates feed-back inhibition by arginine. We determined the crystal structures of both the DUF619 domain-lacking yNAGK, ligand-free as well as complexed with acetylglutamate or acetylglutamate and arginine, and of complete mature yNAGK. While all other known arginine-inhibitable NAGKs are doughnut-like hexameric trimers of dimers of AAK domains, yNAGK has as central structure a flat tetramer formed by two dimers of AAK domains. These dimers differ from canonical AAK dimers in the -110° rotation of one subunit with respect to the other. In the hexameric enzymes, an N-terminal extension, found in all arginine-inhibitable NAGKs, forms a protruding helix that interlaces the dimers. In yNAGK, however, it conforms a two-helix platform that mediates interdimeric interactions. Arginine appears to freeze an open inactive AAK domain conformation. In the complete yNAGK structure, two pairs of DUF619 domains flank the AAK domain tetramer, providing a mechanism for the DUF619 domain modulatory functions. The DUF619 domain exhibits the histone acetyltransferase fold, resembling the catalytic domain of bacterial NAGS. However, the putative acetyl CoA site is blocked, explaining the lack of NAGS activity of yNAGK. We conclude that the tetrameric architecture is an adaptation to metabolon formation and propose an organization for this metabolon, suggesting that yNAGK may be a good model also for yeast and human NAGSs.

Insight on an arginine synthesis metabolon from the tetrameric structure of yeast acetylglutamate kinase.

Directory of Open Access Journals (Sweden)

Sergio de Cima

Full Text Available N-acetyl-L-glutamate kinase (NAGK catalyzes the second, generally controlling, step of arginine biosynthesis. In yeasts, NAGK exists either alone or forming a metabolon with N-acetyl-L-glutamate synthase (NAGS, which catalyzes the first step and exists only within the metabolon. Yeast NAGK (yNAGK has, in addition to the amino acid kinase (AAK domain found in other NAGKs, a ~150-residue C-terminal domain of unclear significance belonging to the DUF619 domain family. We deleted this domain, proving that it stabilizes yNAGK, slows catalysis and modulates feed-back inhibition by arginine. We determined the crystal structures of both the DUF619 domain-lacking yNAGK, ligand-free as well as complexed with acetylglutamate or acetylglutamate and arginine, and of complete mature yNAGK. While all other known arginine-inhibitable NAGKs are doughnut-like hexameric trimers of dimers of AAK domains, yNAGK has as central structure a flat tetramer formed by two dimers of AAK domains. These dimers differ from canonical AAK dimers in the -110° rotation of one subunit with respect to the other. In the hexameric enzymes, an N-terminal extension, found in all arginine-inhibitable NAGKs, forms a protruding helix that interlaces the dimers. In yNAGK, however, it conforms a two-helix platform that mediates interdimeric interactions. Arginine appears to freeze an open inactive AAK domain conformation. In the complete yNAGK structure, two pairs of DUF619 domains flank the AAK domain tetramer, providing a mechanism for the DUF619 domain modulatory functions. The DUF619 domain exhibits the histone acetyltransferase fold, resembling the catalytic domain of bacterial NAGS. However, the putative acetyl CoA site is blocked, explaining the lack of NAGS activity of yNAGK. We conclude that the tetrameric architecture is an adaptation to metabolon formation and propose an organization for this metabolon, suggesting that yNAGK may be a good model also for yeast and human NAGSs.

Proteins involved in flor yeast carbon metabolism under biofilm formation conditions.

Science.gov (United States)

Moreno-García, Jaime; García-Martínez, Teresa; Moreno, Juan; Mauricio, Juan Carlos

2015-04-01

A lack of sugars during the production of biologically aged wines after fermentation of grape must causes flor yeasts to metabolize other carbon molecules formed during fermentation (ethanol and glycerol, mainly). In this work, a proteome analysis involving OFFGEL fractionation prior to LC/MS detection was used to elucidate the carbon metabolism of a flor yeast strain under biofilm formation conditions (BFC). The results were compared with those obtained under non-biofilm formation conditions (NBFC). Proteins associated to processes such as non-fermentable carbon uptake, the glyoxylate and TCA cycles, cellular respiration and inositol metabolism were detected at higher concentrations under BFC than under the reference conditions (NBFC). This study constitutes the first attempt at identifying the flor yeast proteins responsible for the peculiar sensory profile of biologically aged wines. A better metabolic knowledge of flor yeasts might facilitate the development of effective strategies for improved production of these special wines. Copyright © 2014 Elsevier Ltd. All rights reserved.

Polyglutamine toxicity in yeast induces metabolic alterations and mitochondrial defects

KAUST Repository

Papsdorf, Katharina; Kaiser, Christoph J. O.; Drazic, Adrian; Grö tzinger, Stefan W.; Haeß ner, Carmen; Eisenreich, Wolfgang; Richter, Klaus

2015-01-01

formation. Indeed, we find that in vivo iron concentrations are misbalanced and observe a reduction in the activity of the prominent Fe-S cluster containing protein aconitase. Like in other yeast strains with impaired mitochondria, non-fermentative growth

Spent brewer's yeast extract as an ingredient in cooked hams.

Science.gov (United States)

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

2016-11-01

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

Classifying prion and prion-like phenomena.

Science.gov (United States)

Harbi, Djamel; Harrison, Paul M

2014-01-01

The universe of prion and prion-like phenomena has expanded significantly in the past several years. Here, we overview the challenges in classifying this data informatically, given that terms such as "prion-like", "prion-related" or "prion-forming" do not have a stable meaning in the scientific literature. We examine the spectrum of proteins that have been described in the literature as forming prions, and discuss how "prion" can have a range of meaning, with a strict definition being for demonstration of infection with in vitro-derived recombinant prions. We suggest that although prion/prion-like phenomena can largely be apportioned into a small number of broad groups dependent on the type of transmissibility evidence for them, as new phenomena are discovered in the coming years, a detailed ontological approach might be necessary that allows for subtle definition of different "flavors" of prion / prion-like phenomena.

Biosynthesis of diphthamide in the yeast Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Chen, J.Y.C.

1985-01-01

Inactivation of EF-2 by diphtheria toxin requires the presence of a posttranslationally synthesized amino acid residue, diphthamide. The present work was undertaken to study the biosynthetic mechanism of diphthamide synthesis in the yeast Saccharomyces cerevisiae in order to gain better understanding of the biological roles of this unique amino acid residue. Thirty-one haploid ADP-ribosylation-negative mutants, comprising 5 complementation groups, were obtained. One of these mutants contains a toxin-resistant form of EF-2 which can be converted to a toxin-sensitive form through the methylation reaction catalyzed by a S-AdoMet:EF-2 methyltransferase enzyme which is present in other yeast strains. The [ 3 He]methylated residue in the EF-2 modified by the methyltransferase in the presence of S-Ado-L-[ 3 H-methyl]-Met has been analyzed chromatographically following both acid and enzymatic hydrolysis. At the conclusion of the reaction, all of the radiolabel was recovered as diphthine (the unamidated form of diphthamide). The authors conclude that the S-AdoMet:EF-2-methyltransferase is specific for the addition of at least the last two of the three methyl groups present in diphthine

Yeast ecology of Kombucha fermentation.

Science.gov (United States)

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

2004-09-01

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

Waste forms for plutonium disposition

International Nuclear Information System (INIS)

Johnson, S.G.; O'Holleran, T.P.; Frank, S.M.; Meyer, M.K.; Hanson, M.; Staples, B.A.; Knecht, D.A.; Kong, P.C.

1997-01-01

The field of plutonium disposition is varied and of much importance, since the Department of Energy has decided on the hybrid option for disposing of the weapons materials. This consists of either placing the Pu into mixed oxide fuel for reactors or placing the material into a stable waste form such as glass. The waste form used for Pu disposition should exhibit certain qualities: (1) provide for a suitable deterrent to guard against proliferation; (2) be of minimal volume, i.e., maximize the loading; and (3) be reasonably durable under repository-like conditions. This paper will discuss several Pu waste forms that display promising characteristics

Selection of Ethanol-Tolerant Yeast Hybrids in pH-Regulated Continuous Culture

OpenAIRE

Jiménez, Juan; Benítez, Tahía

1988-01-01

Hybrids between naturally occurring wine yeast strains and laboratory strains were formed as a method of increasing genetic variability to improve the ethanol tolerance of yeast strains. The hybrids were subjected to competition experiments under continuous culture controlled by pH with increasing ethanol concentrations over a wide range to select the fastest-growing strain at any concentration of ethanol. The continuous culture system was obtained by controlling the dilution rate of a chemos...

Yeast genome sequencing:

DEFF Research Database (Denmark)

Piskur, Jure; Langkjær, Rikke Breinhold

2004-01-01

For decades, unicellular yeasts have been general models to help understand the eukaryotic cell and also our own biology. Recently, over a dozen yeast genomes have been sequenced, providing the basis to resolve several complex biological questions. Analysis of the novel sequence data has shown...... of closely related species helps in gene annotation and to answer how many genes there really are within the genomes. Analysis of non-coding regions among closely related species has provided an example of how to determine novel gene regulatory sequences, which were previously difficult to analyse because...... they are short and degenerate and occupy different positions. Comparative genomics helps to understand the origin of yeasts and points out crucial molecular events in yeast evolutionary history, such as whole-genome duplication and horizontal gene transfer(s). In addition, the accumulating sequence data provide...

Evidence for a Pneumocystis carinii Flo8-like transcription factor: insights into organism adhesion.

Science.gov (United States)

Kottom, Theodore J; Limper, Andrew H

2016-02-01

Pneumocystis carinii (Pc) adhesion to alveolar epithelial cells is well established and is thought to be a prerequisite for the initiation of Pneumocystis pneumonia. Pc binding events occur in part through the major Pc surface glycoprotein Msg, as well as an integrin-like molecule termed PcInt1. Recent data from the Pc sequencing project also demonstrate DNA sequences homologous to other genes important in Candida spp. binding to mammalian host cells, as well as organism binding to polystyrene surfaces and in biofilm formation. One of these genes, flo8, a transcription factor needed for downstream cAMP/PKA-pathway-mediated activation of the major adhesion/flocculin Flo11 in yeast, was cloned from a Pc cDNA library utilizing a partial sequence available in the Pc genome database. A CHEF blot of Pc genomic DNA yielded a single band providing evidence this gene is present in the organism. BLASTP analysis of the predicted protein demonstrated 41 % homology to the Saccharomyces cerevisiae Flo8. Northern blotting demonstrated greatest expression at pH 6.0-8.0, pH comparable to reported fungal biofilm milieu. Western blot and immunoprecipitation assays of PcFlo8 protein in isolated cyst and tropic life forms confirmed the presence of the cognate protein in these Pc life forms. Heterologous expression of Pcflo8 cDNA in flo8Δ-deficient yeast strains demonstrated that the Pcflo8 was able to restore yeast binding to polystyrene and invasive growth of yeast flo8Δ cells. Furthermore, Pcflo8 promoted yeast binding to HEK293 human epithelial cells, strengthening its functional classification as a Flo8 transcription factor. Taken together, these data suggest that PcFlo8 is expressed by Pc and may exert activity in organism adhesion and biofilm formation.

Assessment of FUN-1 vital dye staining: Yeast with a block in the vacuolar sorting pathway have impaired ability to form CIVS when stained with FUN-1 fluorescent dye.

Science.gov (United States)

Essary, Brandin D; Marshall, Pamela A

2009-08-01

FUN-1 [2-chloro-4-(2,3-dihydro-3-methyl-(benzo-1,3-thiazol-2-yl)-methylidene)-1-phenylquinolinium iodide] is a fluorescent dye used in studies of yeast and other fungi to monitor cell viability in the research lab and to assay for active fungal infection in the clinical setting. When the plasma membrane is intact, fungal cells internalize FUN-1 and the dye is seen as diffuse green cytosolic fluorescence. FUN-1 is then transported to the vacuole in metabolically active wild type cells and subsequently is compacted into fluorescent red cylindrical intravacuolar structures (CIVS) by an unknown transport pathway. This dye is used to determine yeast viability, as only live cells form CIVS. However, in live Saccharomyces cerevisiae with impaired protein sorting to the yeast vacuole, we report decreased to no CIVS formation, depending on the cellular location of the block in the sorting pathway. Cells with a block in vesicle-mediated transport from the Golgi to prevacuolar compartment (PVC) or with a block in recycling from the PVC to the Golgi demonstrate a substantial impairment in CIVS formation. Instead, the FUN-1 dye is seen either in small punctate structures under fluorescence or as diffuse red cytosol under white light. Thus, researchers using FUN-1 should be cognizant of the limitations of this procedure in determining cell viability as there are viable yeast mutants with impaired CIVS formation.

Systems Biology for Mapping Genotype-Phenotype Relations in Yeast

KAUST Repository

Nielsen, Jens

2016-01-25

The yeast Saccharomyces cerevisiae is widely used for production of fuels, chemicals, pharmaceuticals and materials. Through metabolic engineering of this yeast a number of novel new industrial processes have been developed over the last 10 years. Besides its wide industrial use, S. cerevisiae serves as an eukaryal model organism, and many systems biology tools have therefore been developed for this organism. Among these genome-scale metabolic models have shown to be most successful as they easy integrate with omics data and at the same time have been shown to have excellent predictive power. Despite our extensive knowledge of yeast metabolism and its regulation we are still facing challenges when we want to engineer complex traits, such as improved tolerance to toxic metabolites like butanol and elevated temperatures or when we want to engineer the highly complex protein secretory pathway. In this presentation it will be demonstrated how we can combine directed evolution with systems biology analysis to identify novel targets for rational design-build-test of yeast strains that have improved phenotypic properties. In this lecture an overview of systems biology of yeast will be presented together with examples of how genome-scale metabolic modeling can be used for prediction of cellular growth at different conditions. Examples will also be given on how adaptive laboratory evolution can be used for identifying targets for improving tolerance towards butanol, increased temperature and low pH and for improving secretion of heterologous proteins.

NetPhosYeast: prediction of protein phosphorylation sites in yeast

DEFF Research Database (Denmark)

Ingrell, C.R.; Miller, Martin Lee; Jensen, O.N.

2007-01-01

sites compared to those in humans, suggesting the need for an yeast-specific phosphorylation site predictor. NetPhosYeast achieves a correlation coefficient close to 0.75 with a sensitivity of 0.84 and specificity of 0.90 and outperforms existing predictors in the identification of phosphorylation sites...

Facile synthesis of high-temperature (1000 °C) phase-stable rice-like anatase TiO2 nanocrystals

Science.gov (United States)

Lv, Lizhen; Chen, Qirong; Liu, Xiuyun; Wang, Miaomiao; Meng, Xiangfu

2015-05-01

High-temperature phase-stable rice-like anatase TiO2 nanocrystals were synthesized by one-pot solvothermal method using soluble titania xerogel and isopropyl alcohol (IPA) as the precursor and the solvent, respectively. Sample characterization was carried out by powder X-ray diffraction, high-resolution transmission electron microscopy, field emission scanning electron microscope, X-ray photoelectron spectroscopy, and N2 adsorption-desorption isotherms. The results showed that TiO2 nanocrystals had rice-like shapes with an average size of 5 nm in width and 35 nm in length. The BET surface area was 153 m2/g. Unexpectedly, the rice-like TiO2 nanocrystals exhibited high-temperature phase stability, which could remain as pure anatase phase after calcinations at 1000 °C. Growth mechanism investigation revealed that the IPA solvent played a key role in nucleation and growth of rice-like anatase TiO2 nanocrystals. The photodegradation of rhodamine B demonstrated that rice-like anatase TiO2 nanocrystals exhibited enhanced photocatalytic activity under visible light irradiation.

Effect of carbon source on the accumulation of cytochrome P-450 in the yeast Saccharomyces cerevisiae.

OpenAIRE

Kärenlampi, S O; Marin, E; Hänninen, O O

1981-01-01

The appearance of cytochrome P-450 in the yeast Saccharomyces cerevisiae depended on the substrate supporting growth. Cytochrome P-450 was apparent in yeast cells grown on a strongly fermentable sugar such as D-glucose, D-fructose or sucrose. When yeast was grown on D-galactose, D-mannose or maltose, where fermentation and respiration occurred concomitantly, cytochrome P-450 was also formed. The cytochrome P-450 concentration was maximal at the beginning of the stationary phase of the culture...

Membrane-Sculpting BAR Domains Generate Stable Lipid Microdomains

Science.gov (United States)

Zhao, Hongxia; Michelot, Alphée; Koskela, Essi V.; Tkach, Vadym; Stamou, Dimitrios; Drubin, David G.; Lappalainen, Pekka

2014-01-01

SUMMARY Bin-Amphiphysin-Rvs (BAR) domain proteins are central regulators of many cellular processes involving membrane dynamics. BAR domains sculpt phosphoinositide-rich membranes to generate membrane protrusions or invaginations. Here, we report that, in addition to regulating membrane geometry, BAR domains can generate extremely stable lipid microdomains by “freezing” phosphoinositide dynamics. This is a general feature of BAR domains, because the yeast endocytic BAR and Fes/CIP4 homology BAR (F-BAR) domains, the inverse BAR domain of Pinkbar, and the eisosomal BAR protein Lsp1 induced phosphoinositide clustering and halted lipid diffusion, despite differences in mechanisms of membrane interactions. Lsp1 displays comparable low diffusion rates in vitro and in vivo, suggesting that BAR domain proteins also generate stable phosphoinositide microdomains in cells. These results uncover a conserved role for BAR superfamily proteins in regulating lipid dynamics within membranes. Stable microdomains induced by BAR domain scaffolds and specific lipids can generate phase boundaries and diffusion barriers, which may have profound impacts on diverse cellular processes. PMID:24055060

The essence of yeast quiescence.

Science.gov (United States)

De Virgilio, Claudio

2012-03-01

Like all microorganisms, yeast cells spend most of their natural lifetime in a reversible, quiescent state that is primarily induced by limitation for essential nutrients. Substantial progress has been made in defining the features of quiescent cells and the nutrient-signaling pathways that shape these features. A view that emerges from the wealth of new data is that yeast cells dynamically configure the quiescent state in response to nutritional challenges by using a set of key nutrient-signaling pathways, which (1) regulate pathway-specific effectors, (2) converge on a few regulatory nodes that bundle multiple inputs to communicate unified, graded responses, and (3) mutually modulate their competences to transmit signals. Here, I present an overview of our current understanding of the architecture of these pathways, focusing on how the corresponding core signaling protein kinases (i.e. PKA, TORC1, Snf1, and Pho85) are wired to ensure an adequate response to nutrient starvation, which enables cells to tide over decades, if not centuries, of famine. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Mastite micótica em ruminantes causada por leveduras Mycotic mastitis in ruminants caused by yeasts

Directory of Open Access Journals (Sweden)

Andréia Spanamberg

2009-02-01

Full Text Available A ocorrência de casos esporádicos de mastite causados por microrganismos de origem ambiental pode ser considerada como emergente e as leveduras, os fungos leveduriformes e os filamentosos são alguns dos principais agentes envolvidos. Em relação à mastite micótica, as leveduras são freqüentemente causas de infecções da glândula mamária em animais produtores de leite. A maior parte dos casos ocorre sob a forma de surtos localizados e/ou após tratamento com antimicrobianos. Os principais gêneros envolvidos são Candida e Cryptococcus, além de outros como Geotrichum, Pichia e Trichosporon. O objetivo do trabalho é revisar os aspectos gerais sobre a mastite micótica causada por leveduras e fungos leveduriformes, tais como etiologia, causas predisponentes, patogenicidade, diagnóstico, tratamento e profilaxia por meio de uma abordagem cronológica dos primeiros relatos, mas com enfoque principal nos resultados descritos recentemente na literatura veterinária nacional e internacional. O controle da mastite micótica é fundamentado em métodos preventivos, como adequado manejo da ordenha, correta higienização dos equipamentos e das instalações, com a finalidade de reduzir o número de animais acometidos, além de garantir a qualidade e a inocuidade dos produtos lácteos.The veterinary literature registers sporadic cases of infections caused by environmental microorganisms in which the main agents involved are yeasts, yeasts-like and filamentous fungi. In relation to dairy animals, the yeasts are more frequently incriminated as the aetiological agents of mycotic mastitis. Most cases occur under the form of localized outbreaks and / or after treatment with antimicrobial agents. The main genera involved in mastitis are Candida and Cryptococcus, besides others such as Geotrichum, Pichia and Trichosporon. The purpose of this review is to point out the main aspects of mastitis caused by yeasts and yeast-like fungi, such as etiology

Yeast population dynamics during prefermentative cold soak of Cabernet Sauvignon and Malbec wines.

Science.gov (United States)

Maturano, Y Paola; Mestre, M Victoria; Esteve-Zarzoso, Braulio; Nally, María Cristina; Lerena, María Cecilia; Toro, María Eugenia; Vazquez, Fabio; Combina, Mariana

2015-04-16

Prefermentative cold soak is a widely used technique in red wine production, but the impact on the development of native yeast species is hardly described. The aim of this work was to analyse the dynamics and diversity of yeast populations during prefermentative cold soak in red wines. Three different temperatures (14 ± 1 °C; 8 ± 1 °C and 2.5 ± 1 °C) were used for prefermentative cold soak in Cabernet Sauvignon and Malbec grape musts. Saccharomyces and non-Saccharomyces populations during cold soak and alcoholic fermentation were analysed. In addition, the impact on chemical and sensory properties of the wines was examined. Yeast dynamics during prefermentative cold soak were temperature dependent. At 14 ± 1 °C, the total yeast population progressively increased throughout the cold soak period. Conversely, at 2.5 ± 1 °C, the yeast populations maintained stable during the same period. Prefermentative cold soak conducted at 14±1°C favoured development of Hanseniospora uvarum and Candida zemplinina, whereas cold soak conducted at 8 ± 1 °C favoured growth of Saccharomyces cerevisiae. At 2.5 ± 1 °C, no changes in yeast species were recorded. Acidity and bitterness, two sensory descriptors, appear to be related to wines produced with prefermentative cold soak carried out at 14 ± 1 °C. This fact could be associated with the increase in non-Saccharomyces during the prefermentation stage. Our results emphasise the importance of the temperature as a determinant factor to allow an increase in non-Saccharomyces population during prefermentative cold soak and consequently to modify sensorial attributes of wines as well as their sensorial impact. Copyright © 2015 Elsevier B.V. All rights reserved.

Altered Fermentation Performances, Growth, and Metabolic Footprints Reveal Competition for Nutrients between Yeast Species Inoculated in Synthetic Grape Juice-Like Medium

Directory of Open Access Journals (Sweden)

Stephanie Rollero

2018-02-01

Full Text Available The sequential inoculation of non-Saccharomyces yeasts and Saccharomyces cerevisiae in grape juice is becoming an increasingly popular practice to diversify wine styles and/or to obtain more complex wines with a peculiar microbial footprint. One of the main interactions is competition for nutrients, especially nitrogen sources, that directly impacts not only fermentation performance but also the production of aroma compounds. In order to better understand the interactions taking place between non-Saccharomyces yeasts and S. cerevisiae during alcoholic fermentation, sequential inoculations of three yeast species (Pichia burtonii, Kluyveromyces marxianus, Zygoascus meyerae with S. cerevisiae were performed individually in a synthetic medium. Different species-dependent interactions were evidenced. Indeed, the three sequential inoculations resulted in three different behaviors in terms of growth. P. burtonii and Z. meyerae declined after the inoculation of S. cerevisiae which promptly outcompeted the other two species. However, while the presence of P. burtonii did not impact the fermentation kinetics of S. cerevisiae, that of Z. meyerae rendered the overall kinetics very slow and with no clear exponential phase. K. marxianus and S. cerevisiae both declined and became undetectable before fermentation completion. The results also demonstrated that yeasts differed in their preference for nitrogen sources. Unlike Z. meyerae and P. burtonii, K. marxianus appeared to be a competitor for S. cerevisiae (as evidenced by the uptake of ammonium and amino acids, thereby explaining the resulting stuck fermentation. Nevertheless, the results suggested that competition for other nutrients (probably vitamins occurred during the sequential inoculation of Z. meyerae with S. cerevisiae. The metabolic footprint of the non-Saccharomyces yeasts determined after 48 h of fermentation remained until the end of fermentation and combined with that of S. cerevisiae. For

Altered Fermentation Performances, Growth, and Metabolic Footprints Reveal Competition for Nutrients between Yeast Species Inoculated in Synthetic Grape Juice-Like Medium

Science.gov (United States)

Rollero, Stephanie; Bloem, Audrey; Ortiz-Julien, Anne; Camarasa, Carole; Divol, Benoit

2018-01-01

The sequential inoculation of non-Saccharomyces yeasts and Saccharomyces cerevisiae in grape juice is becoming an increasingly popular practice to diversify wine styles and/or to obtain more complex wines with a peculiar microbial footprint. One of the main interactions is competition for nutrients, especially nitrogen sources, that directly impacts not only fermentation performance but also the production of aroma compounds. In order to better understand the interactions taking place between non-Saccharomyces yeasts and S. cerevisiae during alcoholic fermentation, sequential inoculations of three yeast species (Pichia burtonii, Kluyveromyces marxianus, Zygoascus meyerae) with S. cerevisiae were performed individually in a synthetic medium. Different species-dependent interactions were evidenced. Indeed, the three sequential inoculations resulted in three different behaviors in terms of growth. P. burtonii and Z. meyerae declined after the inoculation of S. cerevisiae which promptly outcompeted the other two species. However, while the presence of P. burtonii did not impact the fermentation kinetics of S. cerevisiae, that of Z. meyerae rendered the overall kinetics very slow and with no clear exponential phase. K. marxianus and S. cerevisiae both declined and became undetectable before fermentation completion. The results also demonstrated that yeasts differed in their preference for nitrogen sources. Unlike Z. meyerae and P. burtonii, K. marxianus appeared to be a competitor for S. cerevisiae (as evidenced by the uptake of ammonium and amino acids), thereby explaining the resulting stuck fermentation. Nevertheless, the results suggested that competition for other nutrients (probably vitamins) occurred during the sequential inoculation of Z. meyerae with S. cerevisiae. The metabolic footprint of the non-Saccharomyces yeasts determined after 48 h of fermentation remained until the end of fermentation and combined with that of S. cerevisiae. For instance

Designer Yeasts for the Fermentation Industry of the 21st Century

Directory of Open Access Journals (Sweden)

Isak S. Pretorius

2003-01-01

Full Text Available The budding yeast, Saccharomyces cerevisiae, has enjoyed a long and distinguished history in the fermention industry. Owing to its efficiency in producing alcohol, S. cerevisiae is, without doubt, the most important commercial microorganism with GRAS (Generally Regarded As Safe status. By brewing beer and sparkling wine, mankind’s oldest domesticated organism made possible the world’s first biotechnological processes. With the emergence of modern molecular genetics, S. cerevisiae has again been harnessed to shift the frontiers of mankind’s newest revolution, genetic engineering. S. cerevisiae is at the forefront of many of these developments in modern biotechnology. Consequently, the industrial importance of S. cerevisiae has extended beyond traditional fermentation. Today, the products of yeast biotechnologies impinge on many commercially important sectors, including food, beverages, biofuels, chemicals, industrial enzymes, pharmaceuticals, agriculture and the environment. Nevertheless, since ethyl alcohol produced by yeast fermentation is likely to remain the foremost worldwide biotechnological commodity for the foreseeable future, this review focuses on advances made with respect to the development of tailor- made yeast strains for the fermented beverage and biofuel industries.

The Affinity of the S9.6 Antibody for Double-Stranded RNAs Impacts the Accurate Mapping of R-Loops in Fission Yeast.

Science.gov (United States)

Hartono, Stella R; Malapert, Amélie; Legros, Pénélope; Bernard, Pascal; Chédin, Frédéric; Vanoosthuyse, Vincent

2018-02-02

R-loops, which result from the formation of stable DNA:RNA hybrids, can both threaten genome integrity and act as physiological regulators of gene expression and chromatin patterning. To characterize R-loops in fission yeast, we used the S9.6 antibody-based DRIPc-seq method to sequence the RNA strand of R-loops and obtain strand-specific R-loop maps at near nucleotide resolution. Surprisingly, preliminary DRIPc-seq experiments identified mostly RNase H-resistant but exosome-sensitive RNAs that mapped to both DNA strands and resembled RNA:RNA hybrids (dsRNAs), suggesting that dsRNAs form widely in fission yeast. We confirmed in vitro that S9.6 can immuno-precipitate dsRNAs and provide evidence that dsRNAs can interfere with its binding to R-loops. dsRNA elimination by RNase III treatment prior to DRIPc-seq allowed the genome-wide and strand-specific identification of genuine R-loops that responded in vivo to RNase H levels and displayed classical features associated with R-loop formation. We also found that most transcripts whose levels were altered by in vivo manipulation of RNase H levels did not form detectable R-loops, suggesting that prolonged manipulation of R-loop levels could indirectly alter the transcriptome. We discuss the implications of our work in the design of experimental strategies to probe R-loop functions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Differences between flocculating yeast and regular industrial yeast in transcription and metabolite profiling during ethanol fermentation

Directory of Open Access Journals (Sweden)

Lili Li

2017-03-01

Full Text Available Objectives: To improve ethanolic fermentation performance of self-flocculating yeast, difference between a flocculating yeast strain and a regular industrial yeast strain was analyzed by transcriptional and metabolic approaches. Results: The number of down-regulated (industrial yeast YIC10 vs. flocculating yeast GIM2.71 and up-regulated genes were 4503 and 228, respectively. It is the economic regulation for YIC10 that non-essential genes were down-regulated, and cells put more “energy” into growth and ethanol production. Hexose transport and phosphorylation were not the limiting-steps in ethanol fermentation for GIM2.71 compared to YIC10, whereas the reaction of 1,3-disphosphoglycerate to 3-phosphoglycerate, the decarboxylation of pyruvate to acetaldehyde and its subsequent reduction to ethanol were the most limiting steps. GIM2.71 had stronger stress response than non-flocculating yeast and much more carbohydrate was distributed to other bypass, such as glycerol, acetate and trehalose synthesis. Conclusions: Differences between flocculating yeast and regular industrial yeast in transcription and metabolite profiling will provide clues for improving the fermentation performance of GIM2.71.

Continuous ethanol production using yeast immobilized on sugar-cane stalks

Energy Technology Data Exchange (ETDEWEB)

Vasconcelos, J.N. de [Alagoas Univ., Maceio, AL (Brazil). Dept. de Engenharia Quimica]. E-mail: jnunes@ctec.ufal.br; Lopes, C.E. [Pernambuco Univ., Recife, PE (Brazil). Dept. de Antibioticos; Franca, F.P. de [Universidade Federal, Rio de Janeiro, RJ (Brazil). Escola de Quimica. Dept. de Engenharia Bioquimica

2004-09-01

Sugar-cane stalks, 2.0 cm long, were used as a support for yeast immobilization envisaging ethanol production. The assays were conducted in 38.5 L fermenters containing a bed of stalks with 50% porosity. The operational stability of the immobilized yeast, the efficiency and stability of the process, as well as the best dilution rate were evaluated. Molasses from demerara sugar production was used in the medium formulation. It was diluted to obtain 111.75 {+-} 1.51 g/L without any further treatment. Sulfuric acid was used to adjust the pH value to around 4.2. Every two days Kamoran HJ (10 ppm) or with a mixture containing penicillin (10 ppm) and tetracycline (10 ppm), was added to the medium. Ethanol yield and efficiency were 29.64 g/L.h and 86.40%, respectively, and the total reducing sugars conversion was 74.61% at a dilution rate of 0.83 h{sup -1}. The yeast-stalk system was shown to be stable for over a 60 day period at extremely variable dilution rates ranging from 0.05 h{sup -1} to 3.00 h{sup -1}. The concentration of immobilized cell reached around 109 cells/gram of dry sugar-cane stalk when the fermenter was operating at the highest dilution rate (3.00 h{sup -1}). (author)

Mechanisms of uv mutagenesis in yeast and E. coli

International Nuclear Information System (INIS)

Lawrence, C.; Christensen, R.; Christensen, J.R.; O'Brien, T.

1983-01-01

Experiments investigating ultraviolet light mutagenesis in either bakers' yeast, Saccharomyces cerevisiae, or E. coli have led to the following conclusions. First, cyclobutane pyrimidine dimers cause most mutations in both organisms; pyrimidine adducts, such as PyC, can account at best for only a small proportion. 86 percent of forward mutations induced at the E. coli lacI locus can be abolished by photoreactivation under conditions which do not alter the level of recA induction. About 75 percent of the forward mutations induced at the CAN1 locus of yeast could be removed by photoreactivation, a value that lies within the range observed previously for the reversion of CYC1 alleles (60 percent - 97 percent). Second, about 10 percent of the lacI forward mutations are untargeted, a smaller fraction than found previously for cycl-91 reversion in yeast. It is not yet clear whether the two species are really different in this respect, of whether the cycl-91 reversion site is a typical of the yeast genome at large. Third, analysis of reversion frequencies of 20 mutant alleles suggests that about 10 to 25 percent of all replication errors produced by mutagenic mechanisms in uv-irradiated yeast involve additions or deletions of base-pairs, indicating that error-prone repair does not just produce substitutions. Last, the REV1 locus in yeast is concerned with the induction of frameshift mutations at some, but not all, genetic sites, just as found previously for substitution mutations. The function of the REV3 gene is more widely, though not universally, required while the function of the RAD6 gene, like that of the recA locus in E. coli, appears to be necessary for all kinds of uv mutagenesis. E coli genes comparable to REV1 and REV3 have not yet been described; conversely, there does not yet appear to be a yeast equivalent of umuC

Mechanisms of uv mutagenesis in yeast and E. coli

International Nuclear Information System (INIS)

Lawrence, C.; Christensen, R.; Christensen, J.R.; O'Brien, T.

1983-01-01

Experiments investigating ultraviolet light mutagenesis in either bakers' yeast, Saccharomyces cerevisiae, or E. coli have led to the following conclusions. First, cyclobutane pyrimidine dimers cause most mutations in both organisms; pyrimidine adducts, such as PyC, can account at best for only a small proportion. Eighty-six percent of forward mutations induced at the E. coli lacI locus can be abolished by photoreactivation under conditions which do not alter the level of recA induction. About 75 percent of the forward mutations induced at the CAN1 locus of yeast could be removed by photoreactivation, a value that lies within the range observed previously for the reversion of CYC1 alleles (60 percent - 97 percent). Second, about 10 percent of the lacI forward mutations are untargeted, a smaller fraction than found previously for cycl1-91 reversion in yeast. It is not yet clear whether the two species are really different in this respect, or whether the cyc1-91 reversion site is atypical of the yeast genome at large. Third, analysis of reversion frequencies of 20 mutant alleles suggests that about 10 - 25 percent of all replication errors produced by mutagenic mechanisms in UV-irradiated yeast involve additions or deletions of base-pairs, indicating that error-prone repair does not just produce substitutions. Last, the REV1 locus in yeast is concerned with the induction of frameshift mutations at some, but not all, genetic sites, just as found previously for substitution mutations. The function of the REV3 gene is more widely, though not universally, required while the function of the RAD6 gene, like that of the recA locus in E. coli, appears to be necessary for all kinds of UV mutagenesis. E. coli genes comparable to REV1 and REV3 have not yet been described, conversely, there does not yet appear to be a yeast equivalent of umuC. 13 references, 4 tables

Vaginal yeast infections while deployed in Southwest/Central Asia, active component females, U.S. Armed Forces, 2008-2013.

Science.gov (United States)

2014-08-01

In field settings, female service members may not have adequate access to bathrooms, showers, laundry, or sanitary products necessary to maintain adequate feminine hygiene; therefore, service women may be at risk for vaginal yeast infections while deployed. During the 6-year surveillance period, nearly 3,000 U.S. military service women were diagnosed with at least one clinically significant yeast infection while supporting combat operations in Southwest/Central Asia. The crude overall incidence rate was 35.1 per 1,000 person-years (p-yrs). Overall incidence rates were higher among black, non-Hispanic service women, and among those in the Army and Air Force, in enlisted grades, and in communications/intelligence and motor transport occupations. The yearly rate of yeast infections was relatively stable from 2008 through 2010, then decreased in 2011 through 2013. Prior to deploying to austere operational settings, female service members should be provided practical and useful information, realistic training, and material support to decrease the risk of acquiring and increase the effectiveness of treating clinically and military operationally significant yeast infections.

Acquisition of the yeast Kluyveromyces marxianus from unpasteurised milk by a kefir grain enhances kefir quality.

Science.gov (United States)

Gethins, Loughlin; Rea, Mary C; Stanton, Catherine; Ross, R Paul; Kilcawley, Kieran; O'Sullivan, Maurice; Crotty, Suzanne; Morrissey, John P

2016-08-01

Kefir is a fermented milk beverage consumed for nutritional and health tonic benefits in many parts of the world. It is produced by the fermentation of milk with a consortium of bacteria and yeast embedded within a polysaccharide matrix. This consortium is not well defined and can vary substantially between kefir grains. There are little data on the microbial stability of kefir grains, nor on interactions between microbes in the grain and in the milk. To study this, a grain was split, with one half of each stored at -20°C and the other half passaged repeatedly in whole unpasteurised milk. Grains passaged in the unpasteurised milk recovered vigour and acquired the yeast Kluyveromyces marxainus from the milk which was confirmed to be the same strain by molecular typing. Furthermore, these passaged grains produced kefir that was distinguished chemically and organoleptically from the stored grains. Some changes in ultrastructure were also observed by scanning electron microscopy. The study showed that kefir grains can acquire yeast from their environment and the final product can be influenced by these newly acquired yeasts. Kluyveromyces marxianus is considered to be responsible for some of the most important characteristics of kefir so the finding that this yeast is part of the less stable microbiota is significant. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cocoa butter-like lipid production ability of non-oleaginous and oleaginous yeasts under nitrogen-limited culture conditions

DEFF Research Database (Denmark)

Wei, Yongjun; Siewers, Verena; Nielsen, Jens

2017-01-01

Cocoa butter (CB) extracted from cocoa beans is the main raw material for chocolate production. However, growing chocolate demands and limited CB production has resulted in a shortage of CB supply. CB is mainly composed of three different kinds of triacylglycerols (TAGs), POP (C16:0–C18:1–C16......, Saccharomyces cerevisiae CEN.PK113-7D, and five oleaginous yeast strains, Trichosporon oleaginosus DSM11815, Rhodotorula graminis DSM 27356, Lipomyces starkeyi DSM 70296, Rhodosporidium toruloides DSM 70398, and Yarrowia lipolytica CBS 6124, in nitrogen-limited medium and compared their CBL production ability...... and POS at levels of 378 mg TAGs/g dry cell weight, hinting that this yeast may have potential as a CBL production host after further metabolic engineering in future....

Interaction Between Yeasts and Zinc

Science.gov (United States)

Nicola, Raffaele De; Walker, Graeme

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

Yeasts and lactic acid bacteria microbiota from masau (Ziziphus mauritiana) fruits and their fermented fruit pulp in Zimbabwe

NARCIS (Netherlands)

Nyanga, L.K.; Nout, M.J.R.; Gadaga, T.H.; Theelen, R.M.C.; Boekhout, T.; Zwietering, M.H.

2007-01-01

Masau are Zimbabwean wild fruits, which are usually eaten raw and/ or processed into products such as porridge, traditional cakes, mahewu and jam. Yeasts, yeast-like fungi, and lactic acid bacteria present on the unripe, ripe and dried fruits, and in the fermented masau fruits collected from

Antigenic characterisation of yeast-expressed lyssavirus nucleoproteins.

Science.gov (United States)

Kucinskaite, Indre; Juozapaitis, Mindaugas; Serva, Andrius; Zvirbliene, Aurelija; Johnson, Nicholas; Staniulis, Juozas; Fooks, Anthony R; Müller, Thomas; Sasnauskas, Kestutis; Ulrich, Rainer G

2007-12-01

In Europe, three genotypes of the genus Lyssavirus, family Rhabdoviridae, are present, classical rabies virus (RABV, genotype 1), European bat lyssavirus type 1 (EBLV-1, genotype 5) and European bat lyssavirus type 2 (EBLV-2, genotype 6). The entire authentic nucleoprotein (N protein) encoding sequences of RABV (challenge virus standard, CVS, strain), EBLV-1 and EBLV-2 were expressed in yeast Saccharomyces cerevisiae at high level. Purification of recombinant N proteins by caesium chloride gradient centrifugation resulted in yields between 14-17, 25-29 and 18-20 mg/l of induced yeast culture for RABV-CVS, EBLV-1 and EBLV-2, respectively. The purified N proteins were evaluated by negative staining electron microscopy, which revealed the formation of nucleocapsid-like structures. The antigenic conformation of the N proteins was investigated for their reactivity with monoclonal antibodies (mAbs) directed against different lyssaviruses. The reactivity pattern of each mAb was virtually identical between immunofluorescence assay with virus-infected cells, and ELISA and dot blot assay using the corresponding recombinant N proteins. These observations lead us to conclude that yeast-expressed lyssavirus N proteins share antigenic properties with naturally expressed virus protein. These recombinant proteins have the potential for use as components of serological assays for lyssaviruses.

Characterization of the minimum domain required for targeting budding yeast myosin II to the site of cell division

Directory of Open Access Journals (Sweden)

Tolliday Nicola J

2006-06-01

Full Text Available Abstract Background All eukaryotes with the exception of plants use an actomyosin ring to generate a constriction force at the site of cell division (cleavage furrow during mitosis and meiosis. The structure and filament forming abilities located in the C-terminal or tail region of one of the main components, myosin II, are important for localising the molecule to the contractile ring (CR during cytokinesis. However, it remains poorly understood how myosin II is recruited to the site of cell division and how this recruitment relates to myosin filament assembly. Significant conservation between species of the components involved in cytokinesis, including those of the CR, allows the use of easily genetically manipulated organisms, such as budding yeast (Saccharomyces cerevisiae, in the study of cytokinesis. Budding yeast has a single myosin II protein, named Myo1. Unlike most other class II myosins, the tail of Myo1 has an irregular coiled coil. In this report we use molecular genetics, biochemistry and live cell imaging to characterize the minimum localisation domain (MLD of budding yeast Myo1. Results We show that the MLD is a small region in the centre of the tail of Myo1 and that it is both necessary and sufficient for localisation of Myo1 to the yeast bud neck, the pre-determined site of cell division. Hydrodynamic measurements of the MLD, purified from bacteria or yeast, show that it is likely to exist as a trimer. We also examine the importance of a small region of low coiled coil forming probability within the MLD, which we call the hinge region. Removal of the hinge region prevents contraction of the CR. Using fluorescence recovery after photobleaching (FRAP, we show that GFP-tagged MLD is slightly more dynamic than the GFP-tagged full length molecule but less dynamic than the GFP-tagged Myo1 construct lacking the hinge region. Conclusion Our results define the intrinsic determinant for the localization of budding yeast myosin II and show

An evolvable oestrogen receptor activity sensor: development of a modular system for integrating multiple genes into the yeast genome

NARCIS (Netherlands)

Fox, J.E.; Bridgham, J.T.; Bovee, T.F.H.; Thornton, J.W.

2007-01-01

To study a gene interaction network, we developed a gene-targeting strategy that allows efficient and stable genomic integration of multiple genetic constructs at distinct target loci in the yeast genome. This gene-targeting strategy uses a modular plasmid with a recyclable selectable marker and a

Formation by yeast of 2-furanmethanethiol and ethyl 2-mercaptopropionate aroma compounds in Japanese soy sauce.

Science.gov (United States)

Meng, Qi; Hatakeyama, Makoto; Sugawara, Etsuko

2014-01-01

Two aroma compounds of volatile thiols, 2-furanmethanethiol (2FM) and ethyl 2-mercaptopropionate (ET2MP), were formed in five types of Japanese soy sauce during fermentation by yeast. The concentrations of 2FM and ET2MP in the soy sauce samples increased during alcoholic fermentation. The concentrations of 2FM and ET2MP were higher in the soy sauce fermented by Zygosaccharomyces rouxii than in that fermented by Candida versatilis. The enantiomers of ET2MP were separated by gas chromatography in a capillary column. The average enantiomeric ratio of ET2MP in the soy sauce was approximately 1:1. 2FM was formed by yeast in a medium prepared from cysteine and furfural, and cysteine is considered the key precursor of 2FM by yeast in soy sauce.

Chemical genomic guided engineering of gamma-valerolactone tolerant yeast.

Science.gov (United States)

Bottoms, Scott; Dickinson, Quinn; McGee, Mick; Hinchman, Li; Higbee, Alan; Hebert, Alex; Serate, Jose; Xie, Dan; Zhang, Yaoping; Coon, Joshua J; Myers, Chad L; Landick, Robert; Piotrowski, Jeff S

2018-01-12

Gamma valerolactone (GVL) treatment of lignocellulosic bomass is a promising technology for degradation of biomass for biofuel production; however, GVL is toxic to fermentative microbes. Using a combination of chemical genomics with the yeast (Saccharomyces cerevisiae) deletion collection to identify sensitive and resistant mutants, and chemical proteomics to monitor protein abundance in the presence of GVL, we sought to understand the mechanism toxicity and resistance to GVL with the goal of engineering a GVL-tolerant, xylose-fermenting yeast. Chemical genomic profiling of GVL predicted that this chemical affects membranes and membrane-bound processes. We show that GVL causes rapid, dose-dependent cell permeability, and is synergistic with ethanol. Chemical genomic profiling of GVL revealed that deletion of the functionally related enzymes Pad1p and Fdc1p, which act together to decarboxylate cinnamic acid and its derivatives to vinyl forms, increases yeast tolerance to GVL. Further, overexpression of Pad1p sensitizes cells to GVL toxicity. To improve GVL tolerance, we deleted PAD1 and FDC1 in a xylose-fermenting yeast strain. The modified strain exhibited increased anaerobic growth, sugar utilization, and ethanol production in synthetic hydrolysate with 1.5% GVL, and under other conditions. Chemical proteomic profiling of the engineered strain revealed that enzymes involved in ergosterol biosynthesis were more abundant in the presence of GVL compared to the background strain. The engineered GVL strain contained greater amounts of ergosterol than the background strain. We found that GVL exerts toxicity to yeast by compromising cellular membranes, and that this toxicity is synergistic with ethanol. Deletion of PAD1 and FDC1 conferred GVL resistance to a xylose-fermenting yeast strain by increasing ergosterol accumulation in aerobically grown cells. The GVL-tolerant strain fermented sugars in the presence of GVL levels that were inhibitory to the unmodified strain

Entropy analysis in yeast DNA

International Nuclear Information System (INIS)

Kim, Jongkwang; Kim, Sowun; Lee, Kunsang; Kwon, Younghun

2009-01-01

In this article, we investigate the language structure in yeast 16 chromosomes. In order to find it, we use the entropy analysis for codons (or amino acids) of yeast 16 chromosomes, developed in analysis of natural language by Montemurro et al. From the analysis, we can see that there exists a language structure in codons (or amino acids) of yeast 16 chromosomes. Also we find that the grammar structure of amino acids of yeast 16 chromosomes has a deep relationship with secondary structure of protein.

Evaluation of Different Yeast Species for Improving Fermentation of Cereal Straws

Directory of Open Access Journals (Sweden)

Zuo Wang

2016-02-01

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

The truth about mouse, human, worms and yeast

Directory of Open Access Journals (Sweden)

Nelson David R

2004-01-01

Full Text Available Abstract Genome comparisons are behind the powerful new annotation methods being developed to find all human genes, as well as genes from other genomes. Genomes are now frequently being studied in pairs to provide cross-comparison datasets. This 'Noah's Ark' approach often reveals unsuspected genes and may support the deletion of false-positive predictions. Joining mouse and human as the cross-comparison dataset for the first two mammals are: two Drosophila species, D. melanogaster and D. pseudoobscura; two sea squirts, Ciona intestinalis and Ciona savignyi; four yeast (Saccharomyces species; two nematodes, Caenorhabditis elegans and Caenorhabditis briggsae; and two pufferfish (Takefugu rubripes and Tetraodon nigroviridis. Even genomes like yeast and C. elegans, which have been known for more than five years, are now being significantly improved. Methods developed for yeast or nematodes will now be applied to mouse and human, and soon to additional mammals such as rat and dog, to identify all the mammalian protein-coding genes. Current large disparities between human Unigene predictions (127,835 genes and gene-scanning methods (45,000 genes still need to be resolved. This will be the challenge during the next few years.

Development of intra-strain self-cloning procedure for breeding baker's yeast strains.

Science.gov (United States)

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

2017-03-01

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

Polymorphic drugs examined with neutron spectroscopy: Is making more stable forms really that simple?

DEFF Research Database (Denmark)

Tsapatsaris, Nikolaos; Landsgesell, Sven; Koza, Michael Marek

2013-01-01

Understanding  polymorphism  in  pharmaceutical  ingredients  is  a   long-­  standing  challenge.  A  well-­known  example  is  paracetamol,  C8H9NO2.   The  marketed  stable  form  I  crystallizes  with  corrugated  molecular  layers.   In  contrast,  form  II,  which  is  thermodynamically......  favorable  at  high   pressures,  has  relatively  planar  layers  that  can  slip  over  each  other   without  difficulty,    is  metastable  at  ambient  conditions.  By  means  of   inelastic  neutron  scattering  we  demonstrated  that  the  lattice  modes  of   form  II  exhibit  a  sudden  1  me......V  energy  shift  at  300  K  under  a  pressure  of   ca  0.4  GPa.  Moreover,  evidence  of  an  increase  of  the  vibrational  energy   in  both  polymorphs  was  found,  which  was  accompanied,  in  form  I,  by  an   unexpectedly  weak  increase  of  the  tunnel  splitting.  These  results   indicate...

Yeast flocculation: New story in fuel ethanol production.

Science.gov (United States)

Zhao, X Q; Bai, F W

2009-01-01

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

Separable Crossover-Promoting and Crossover-Constraining Aspects of Zip1 Activity during Budding Yeast Meiosis.

Directory of Open Access Journals (Sweden)

Karen Voelkel-Meiman

2015-06-01

Full Text Available Accurate chromosome segregation during meiosis relies on the presence of crossover events distributed among all chromosomes. MutSγ and MutLγ homologs (Msh4/5 and Mlh1/3 facilitate the formation of a prominent group of meiotic crossovers that mature within the context of an elaborate chromosomal structure called the synaptonemal complex (SC. SC proteins are required for intermediate steps in the formation of MutSγ-MutLγ crossovers, but whether the assembled SC structure per se is required for MutSγ-MutLγ-dependent crossover recombination events is unknown. Here we describe an interspecies complementation experiment that reveals that the mature SC is dispensable for the formation of Mlh3-dependent crossovers in budding yeast. Zip1 forms a major structural component of the budding yeast SC, and is also required for MutSγ and MutLγ-dependent crossover formation. Kluyveromyces lactis ZIP1 expressed in place of Saccharomyces cerevisiae ZIP1 in S. cerevisiae cells fails to support SC assembly (synapsis but promotes wild-type crossover levels in those nuclei that progress to form spores. While stable, full-length SC does not assemble in S. cerevisiae cells expressing K. lactis ZIP1, aggregates of K. lactis Zip1 displayed by S. cerevisiae meiotic nuclei are decorated with SC-associated proteins, and K. lactis Zip1 promotes the SUMOylation of the SC central element protein Ecm11, suggesting that K. lactis Zip1 functionally interfaces with components of the S. cerevisiae synapsis machinery. Moreover, K. lactis Zip1-mediated crossovers rely on S. cerevisiae synapsis initiation proteins Zip3, Zip4, Spo16, as well as the Mlh3 protein, as do the crossovers mediated by S. cerevisiae Zip1. Surprisingly, however, K. lactis Zip1-mediated crossovers are largely Msh4/Msh5 (MutSγ-independent. This separation-of-function version of Zip1 thus reveals that neither assembled SC nor MutSγ is required for Mlh3-dependent crossover formation per se in budding yeast

Preparation, Characterization and Thermal Properties of Paraffin Wax – Expanded Perlite Form-Stable Composites for Latent Heat Storage

Directory of Open Access Journals (Sweden)

Tugba GURMEN OZCELIK

2017-02-01

Full Text Available In this study, form-stable composite phase change materials (PCM for latent heat storage were prepared by impregnating paraffin wax into the pores of the expanded perlite (EP. The characterization of the composite PCMs was performed by FTIR, TGA, SEM and DSC analysis. The melting point and heat of fusion were determined for 25 % paraffin included composite, as 54.3 °C and 94.71 J/g and for 45 % paraffin included composite as 53.6 °C and 106.69 J/g, respectively. The FTIR results showed that there were no chemical reaction between the perlite and paraffin. TGA analysis indicated that both composite PCMs had good thermal stability. SEM images showed that the paraffin was dispersed uniformly into the pores and on the EP surface. There was no leakage and degradation at the composite PCMs after heating and cooling cycles. According to the results, both prepared composites showed good thermal energy storage properties, reliability and stability. All results suggested that the presented form- stable composite PCMs has great potential for thermal energy storage applications.DOI: http://dx.doi.org/10.5755/j01.ms.23.1.13661

Brewing characteristics of piezosensitive sake yeasts

Science.gov (United States)

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

2018-04-01

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

Moving stable solitons in Galileon theory

International Nuclear Information System (INIS)

Masoumi, Ali; Xiao Xiao

2012-01-01

Despite the no-go theorem Endlich et al. (2011) which rules out static stable solitons in Galileon theory, we propose a family of solitons that evade the theorem by traveling at the speed of light. These domain-wall-like solitons are stable under small fluctuations-analysis of perturbation shows neither ghost-like nor tachyon-like instabilities, and perturbative collision of these solitons suggests that they pass through each other asymptotically, which maybe an indication of the integrability of the theory itself.

Horizontal gene transfer promoted evolution of the ability to propagate under anaerobic conditions in yeasts

DEFF Research Database (Denmark)

Gojkovic, Zoran; Knecht, Wolfgang; Warneboldt, J.

2004-01-01

The ability to propagate under anaerobic conditions is an essential and unique trait of brewer's or baker's yeast (Saccharomyces cervisiae). To understand the evolution of facultative anaerobiosis we studied the dependence of de novo pyrimidine biosynthesis, more precisely the fourth enzymic...... activity catalysed by dihydroorotate dehydrogenase (DHODase), on the enzymes of the respiratory chain in several yeast species. While the majority of yeasts possess a mitochondrial DHODase, Saccharomyces cerevisiae has a cytoplasmatic enzyme, whose activity is independent of the presence of oxygen. From....... We show that these two S. kluyveri enzymes, and their coding genes, differ in their dependence on the presence of oxygen. Only the cytoplasmic DHODase promotes growth in the absence of oxygen. Apparently a Saccharomyces yeast progenitor which had a eukaryotic-like mitochondrial DHODase acquired...

Membrane compartment of Can1 (MCC): specialized functional microdomain of the yeast plasma membrane

OpenAIRE

Doudová, Lenka

2017-01-01

Membrane compartment of Can1 (MCC): specialized functional microdomain of the yeast plasma membrane Yeast plasma membrane is divided into several different compartments. Membrane compartment of Can1 is specific for its protein and lipid composition, furthermore it creates furrow-like invaginations on the plasma membrane. These invaginations are made by multiprotein complexes called eisosomes, which are located in the cytosolic side of MCCs. It was established that this domain plays an importa...

An insight into the complex prion-prion interaction network in the budding yeast Saccharomyces cerevisiae.

Science.gov (United States)

Du, Zhiqiang; Valtierra, Stephanie; Li, Liming

2014-01-01

The budding yeast Saccharomyces cerevisiae is a valuable model system for studying prion-prion interactions as it contains multiple prion proteins. A recent study from our laboratory showed that the existence of Swi1 prion ([SWI(+)]) and overproduction of Swi1 can have strong impacts on the formation of 2 other extensively studied yeast prions, [PSI(+)] and [PIN(+)] ([RNQ(+)]) (Genetics, Vol. 197, 685-700). We showed that a single yeast cell is capable of harboring at least 3 heterologous prion elements and these prions can influence each other's appearance positively and/or negatively. We also showed that during the de novo [PSI(+)] formation process upon Sup35 overproduction, the aggregation patterns of a preexisting inducer ([RNQ(+)] or [SWI(+)]) can undergo significant remodeling from stably transmitted dot-shaped aggregates to aggregates that co-localize with the newly formed Sup35 aggregates that are ring/ribbon/rod- shaped. Such co-localization disappears once the newly formed [PSI(+)] prion stabilizes. Our finding provides strong evidence supporting the "cross-seeding" model for prion-prion interactions and confirms earlier reports that the interactions among different prions and their prion proteins mostly occur at the initiation stages of prionogenesis. Our results also highlight a complex prion interaction network in yeast. We believe that elucidating the mechanism underlying the yeast prion-prion interaction network will not only provide insight into the process of prion de novo generation and propagation in yeast but also shed light on the mechanisms that govern protein misfolding, aggregation, and amyloidogenesis in higher eukaryotes.

Theoretical study on the cage-like nanostructures formed by amino acids and their potential applications as drug carriers

Science.gov (United States)

Weng, Pei Pei; Fan, Jian Fen; Lin, Hui Fang; Zhao, Xin; Si, Xia Lan

2017-12-01

The cage-like octamer, decamer and dodecamer constructed from aspartic acid monomers have been studied to explore their potential applications as drug carriers using the density functional theory. The calculation results indicate that these stable cage-like oligomers are mainly connected by the -C=O…HOOC- and -HN…HOOC- H-bonds and still keep stability and good drum-shaped topologies after the incorporation of 5-fluorouracil, paraldehyde and C24, respectively. The self-assembled cage-like oligomers may be applied to the preparation of new biological materials and the design of drug delivery systems.

GROWTH RATE AND IDENTIFICATION OF YEASTS IN THREE DIFFERENT MEDIA: FLOUR, SPROUT OF CEREALS AND COMMERCIAL MEDIA

Directory of Open Access Journals (Sweden)

P DEHGHAN

2002-12-01

Full Text Available Introduction. The yeasts are a large group of fungi. In addition to their different uses in food industries and pharmacology they can also cause human and animal infections under predisposing factors. For investigating the yeast"s growth phases and diagnosis of the species, they should culture in media from natural sources like the seeds on the commercial media. According to yeast"s nutritinal requierments and considering the various nutritional materials of seeds like wheat, rice, barney and better use of these seed"s compounds during sprouting, this research was done with the aim of measurment of growth rate and yeasts characterization in such media. Methods. For making seeds media, a fixed quantity of seed"s flour or sprout"s flour was added to a certain amount of agar in acidotic condition (pH=5.8. The germination of seeds was done by Hus method and for colony counting Mc, Farland tubes were used and microscopic and macroscopic characteristics were investigated and compared in both synthetic and seed media Results. The results showed that the rate of yeasts growth in all germinated seeds was more than the seeds themeselves. Statistical analysis showed no significal difference between the growth rate of yeasts in both wheat and barney sprout compared to the commercial media. In the microscopic studies, the species of Candida albicans in wheat flour has produced more chlamydoconidia than the synthetic medium of corn meal agar. Also production of the capsule in C.neoformans in the seed"s media has been better than the synthetic media. Discussion. According to the promising results obtained from the present study regard to the growth rate and differentiation of the fungal species in such media, standardization and mass production of them in our country would seem to be an productive step towards self sufficiency.

Indigenous and inoculated yeast fermentation of gabiroba (Campomanesia pubescens) pulp for fruit wine production.

Science.gov (United States)

Duarte, Whasley Ferreira; Dias, Disney Ribeiro; de Melo Pereira, Gilberto Vinicius; Gervásio, Ivani Maria; Schwan, Rosane Freitas

2009-04-01

The objectives of this study were to evaluate the potential of gabiroba Campomanesia pubescens (DC) O. Berg in the production of a beverage fermented using selected and wild yeasts from indigenous fermentation, analyze the volatile compounds profile present during the process of fermentation, and evaluate the sensory quality of the final beverage produced. Throughout the process of fermentation, when Saccharomyces cerevisiae UFLA CA 1162 was inoculated, there were stable viable populations around 9 log cells ml(-1). During indigenous fermentation, yeast population increased from 3.7 log CFU ml(-1) to 8.1 log CFU ml(-1) after 14 days. The diversity and dynamics of the yeast population during indigenous fermentation observed by PFGE analysis showed five different karyotyping profiles in the first days of fermentation. After the seventh day, there was a higher frequency of a similar S. cerevisiae profile. The yeast non-Saccharomyces were identified by sequencing of the ITS region as Candida quercitrusa and Issatchenkia terricola. Inoculated fermentations yielded a higher amount of alcohol than indigenous ones, indicating the efficiency of selected strains. There was also a greater concentration of higher alcohols, which are usually responsible for the flavor found in alcoholic beverages. Based on the characteristics of the pulp and acceptance in the sensory analysis, gabiroba fruits showed good potential for use in the production of fermented beverage.

Study on the effects of near-future ocean acidification on marine yeasts: a microcosm approach

Science.gov (United States)

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

2013-12-01

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

Analysis of Mcm2-7 chromatin binding during anaphase and in the transition to quiescence in fission yeast

International Nuclear Information System (INIS)

Namdar, Mandana; Kearsey, Stephen E.

2006-01-01

Mcm2-7 proteins are generally considered to function as a heterohexameric complex, providing helicase activity for the elongation step of DNA replication. These proteins are loaded onto replication origins in M-G1 phase in a process termed licensing or pre-replicative complex formation. It is likely that Mcm2-7 proteins are loaded onto chromatin simultaneously as a pre-formed hexamer although some studies suggest that subcomplexes are recruited sequentially. To analyze this process in fission yeast, we have compared the levels and chromatin binding of Mcm2-7 proteins during the fission yeast cell cycle. Mcm subunits are present at approximately 1 x 10 4 molecules/cell and are bound with approximately equal stoichiometry on chromatin in G1/S phase cells. Using a single cell assay, we have correlated the timing of chromatin association of individual Mcm subunits with progression through mitosis. This showed that Mcm2, 4 and 7 associate with chromatin at about the same stage of anaphase, suggesting that licensing involves the simultaneous binding of these subunits. We also examined Mcm2-7 chromatin association when cells enter a G0-like quiescent state. Chromatin binding is lost in this transition in a process that does not require DNA replication or the selective degradation of specific subunits

Ferroelectric nanostructure having switchable multi-stable vortex states

Science.gov (United States)

Naumov, Ivan I [Fayetteville, AR; Bellaiche, Laurent M [Fayetteville, AR; Prosandeev, Sergey A [Fayetteville, AR; Ponomareva, Inna V [Fayetteville, AR; Kornev, Igor A [Fayetteville, AR

2009-09-22

A ferroelectric nanostructure formed as a low dimensional nano-scale ferroelectric material having at least one vortex ring of polarization generating an ordered toroid moment switchable between multi-stable states. A stress-free ferroelectric nanodot under open-circuit-like electrical boundary conditions maintains such a vortex structure for their local dipoles when subject to a transverse inhomogeneous static electric field controlling the direction of the macroscopic toroidal moment. Stress is also capable of controlling the vortex's chirality, because of the electromechanical coupling that exists in ferroelectric nanodots.

Responses of phylloplane yeasts to UV-B (290-320 nm) radiation: interspecific differences in sensitivity

International Nuclear Information System (INIS)

Gunasekera, T.S.; Paul, N.D.; Ayres, P.G.

1997-01-01

The sensitivity to UV-B (290–320 nm) radiation of common phylloplane yeasts from two contrasting UV-B environments was compared in the laboratory using mixtures of white light (PAR: 400–700 nm) and UV-B radiation from artificial lamp sources. Sporidiobolus salmonicolor, Rhodotorula mucilaginosa and Cryptococcus sp., the dominant yeasts on leaves of tea (Camellia sinensis), were isolated in Sri Lanka (SL), while Sporidiobolus sp. and Bullera alba, dominant on faba bean (Vicia faba), were isolated in the U.K. Dose responses were determined separately for each yeast. UV-B reduced colony forming units (due to cell mortality or inactivation) and colony size (due to reduced multiplication) of all yeasts. The LD 50 values and doses causing 50% reduction of cells per colony were higher for SL isolates than U.K. isolates. Results indicated that each yeast is somewhat vulnerable to UV-B doses representative of its natural habitat. The relative insensitivity of SL isolates was shown when SL and U.K. isolates were irradiated simultaneously with the same dose of UV-B. Of the two U.K. yeasts, B. alba was significantly more sensitive than Sporidiobolus sp. to UV-B. Except for R. mucilaginosa from SL, all yeasts demonstrated some photorepair in the presence of white light. White light provided relatively little protection for the U.K. isolate of Sporidiobolus sp. although it allowed increased colony size. The spectral responses of Sporidiobolus sp. (U.K.) and of B. alba (U.K.) were broadly similar. Wavelengths longer than 320 nm had no measurable effect on colony forming units. However, colony survival was significantly reduced at 310 nm and all shorter wavebands. No colonies were counted at 290 nm or below. (author)

Effect of poly-A:U, dextran sulfate and yeast RNA on the bone marrow colony-forming ability in irradiated mice

International Nuclear Information System (INIS)

Chernyavskij, V.I.; Lysenko, A.I.; Kulakova, G.S.

1977-01-01

It has been shown, that poly-A:U, dextran sulfate and yeast RNA increased a number of endogenic colonies (COE) in the mouse spleen sublethally irradiated, as a result of, apparently, their mitogenic effect on proliferous COE. The preparations did not affect the number of exogenic colonies when introducting them together with transfer of syngenic cells of bone marrow, taken from the intact donors. Dextran sulfate increased 2.7 times the number of the endogenic colonies in the spleens of nonuniformly irradiated mice mainly due to the COE migration from protected bone marrow areas. The complex of poly-A:U and yest RNA in such experiment type were ineffective. One of the most important factors in the mechanism of the dextran sulfate adjuvant activity possibly is its ability to increase migration potencies of the stem blood-forming cells

Assessing phagotrophy in the mixotrophic ciliate Paramecium bursaria using GFP-expressing yeast cells.

Science.gov (United States)

Miura, Takashi; Moriya, Hisao; Iwai, Sosuke

2017-07-03

We used cells of the yeast Saccharomyces cerevisiae expressing green fluorescent protein (GFP) as fluorescently labelled prey to assess the phagocytic activities of the mixotrophic ciliate Paramecium bursaria, which harbours symbiotic Chlorella-like algae. Because of different fluorescence spectra of GFP and algal chlorophyll, ingested GFP-expressing yeast cells can be distinguished from endosymbiotic algal cells and directly counted in individual P. bursaria cells using fluorescence microscopy. By using GFP-expressing yeast cells, we found that P. bursaria altered ingestion activities under different physiological conditions, such as different growth phases or the presence/absence of endosymbionts. Use of GFP-expressing yeast cells allowed us to estimate the digestion rates of live prey of the ciliate. In contrast to the ingestion activities, the digestion rate within food vacuoles was not affected by the presence of endosymbionts, consistent with previous findings that food and perialgal vacuoles are spatially and functionally separated in P. bursaria. Thus, GFP-expressing yeast may provide a valuable tool to assess both ingestion and digestion activities of ciliates that feed on eukaryotic organisms. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Large-Scale Selection and Breeding To Generate Industrial Yeasts with Superior Aroma Production

Science.gov (United States)

Steensels, Jan; Meersman, Esther; Snoek, Tim; Saels, Veerle

2014-01-01

The concentrations and relative ratios of various aroma compounds produced by fermenting yeast cells are essential for the sensory quality of many fermented foods, including beer, bread, wine, and sake. Since the production of these aroma-active compounds varies highly among different yeast strains, careful selection of variants with optimal aromatic profiles is of crucial importance for a high-quality end product. This study evaluates the production of different aroma-active compounds in 301 different Saccharomyces cerevisiae, Saccharomyces paradoxus, and Saccharomyces pastorianus yeast strains. Our results show that the production of key aroma compounds like isoamyl acetate and ethyl acetate varies by an order of magnitude between natural yeasts, with the concentrations of some compounds showing significant positive correlation, whereas others vary independently. Targeted hybridization of some of the best aroma-producing strains yielded 46 intraspecific hybrids, of which some show a distinct heterosis (hybrid vigor) effect and produce up to 45% more isoamyl acetate than the best parental strains while retaining their overall fermentation performance. Together, our results demonstrate the potential of large-scale outbreeding to obtain superior industrial yeasts that are directly applicable for commercial use. PMID:25192996

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

Science.gov (United States)

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

2014-03-01

Saccharomyces cerevisiae and grape juice are 'natural companions' and make a happy wine marriage. However, this relationship can be enriched by allowing 'wild' non-Saccharomyces yeast to participate in a sequential manner in the early phases of grape must fermentation. However, such a triangular relationship is complex and can only be taken to 'the next level' if there are no spoilage yeast present and if the 'wine yeast' - S. cerevisiae - is able to exert its dominance in time to successfully complete the alcoholic fermentation. Winemakers apply various 'matchmaking' strategies (e.g. cellar hygiene, pH, SO2 , temperature and nutrient management) to keep 'spoilers' (e.g. Dekkera bruxellensis) at bay, and allow 'compatible' wild yeast (e.g. Torulaspora delbrueckii, Pichia kluyveri, Lachancea thermotolerans and Candida/Metschnikowia pulcherrima) to harmonize with potent S. cerevisiae wine yeast and bring the best out in wine. Mismatching can lead to a 'two is company, three is a crowd' scenario. More than 40 of the 1500 known yeast species have been isolated from grape must. In this article, we review the specific flavour-active characteristics of those non-Saccharomyces species that might play a positive role in both spontaneous and inoculated wine ferments. We seek to present 'single-species' and 'multi-species' ferments in a new light and a new context, and we raise important questions about the direction of mixed-fermentation research to address market trends regarding so-called 'natural' wines. This review also highlights that, despite the fact that most frontier research and technological developments are often focussed primarily on S. cerevisiae, non-Saccharomyces research can benefit from the techniques and knowledge developed by research on the former. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Production of novel antioxidative phenolic amides through heterologous expression of the plant’s chlorogenic acid biosynthesis genes in yeast

NARCIS (Netherlands)

Moglia, A.; Comino, C.; Lanteri, S.; Vos, de C.H.; Waard, de P.; Beek, van T.A.; Goitre, L.; Retta, S.F.; Beekwilder, M.J.

2010-01-01

Phenolic esters like chlorogenic acid play an important role in therapeutic properties of many plant extracts. We aimed to produce phenolic esters in baker’s yeast, by expressing tobacco 4CL and globe artichoke HCT. Indeed yeast produced phenolic esters. However, the primary product was identified

Rice black streaked dwarf virus P7-2 forms a SCF complex through binding to Oryza sativa SKP1-like proteins, and interacts with GID2 involved in the gibberellin pathway.

Science.gov (United States)

Tao, Tao; Zhou, Cui-Ji; Wang, Qian; Chen, Xiang-Ru; Sun, Qian; Zhao, Tian-Yu; Ye, Jian-Chun; Wang, Ying; Zhang, Zong-Ying; Zhang, Yong-Liang; Guo, Ze-Jian; Wang, Xian-Bing; Li, Da-Wei; Yu, Jia-Lin; Han, Cheng-Gui

2017-01-01

As a core subunit of the SCF complex that promotes protein degradation through the 26S proteasome, S-phase kinase-associated protein 1 (SKP1) plays important roles in multiple cellular processes in eukaryotes, including gibberellin (GA), jasmonate, ethylene, auxin and light responses. P7-2 encoded by Rice black streaked dwarf virus (RBSDV), a devastating viral pathogen that causes severe symptoms in infected plants, interacts with SKP1 from different plants. However, whether RBSDV P7-2 forms a SCF complex and targets host proteins is poorly understood. In this study, we conducted yeast two-hybrid assays to further explore the interactions between P7-2 and 25 type I Oryza sativa SKP1-like (OSK) proteins, and found that P7-2 interacted with eight OSK members with different binding affinity. Co-immunoprecipitation assay further confirmed the interaction of P7-2 with OSK1, OSK5 and OSK20. It was also shown that P7-2, together with OSK1 and O. sativa Cullin-1, was able to form the SCF complex. Moreover, yeast two-hybrid assays revealed that P7-2 interacted with gibberellin insensitive dwarf2 (GID2) from rice and maize plants, which is essential for regulating the GA signaling pathway. It was further demonstrated that the N-terminal region of P7-2 was necessary for the interaction with GID2. Overall, these results indicated that P7-2 functioned as a component of the SCF complex in rice, and interaction of P7-2 with GID2 implied possible roles of the GA signaling pathway during RBSDV infection.

Rice black streaked dwarf virus P7-2 forms a SCF complex through binding to Oryza sativa SKP1-like proteins, and interacts with GID2 involved in the gibberellin pathway.

Directory of Open Access Journals (Sweden)

Tao Tao

Full Text Available As a core subunit of the SCF complex that promotes protein degradation through the 26S proteasome, S-phase kinase-associated protein 1 (SKP1 plays important roles in multiple cellular processes in eukaryotes, including gibberellin (GA, jasmonate, ethylene, auxin and light responses. P7-2 encoded by Rice black streaked dwarf virus (RBSDV, a devastating viral pathogen that causes severe symptoms in infected plants, interacts with SKP1 from different plants. However, whether RBSDV P7-2 forms a SCF complex and targets host proteins is poorly understood. In this study, we conducted yeast two-hybrid assays to further explore the interactions between P7-2 and 25 type I Oryza sativa SKP1-like (OSK proteins, and found that P7-2 interacted with eight OSK members with different binding affinity. Co-immunoprecipitation assay further confirmed the interaction of P7-2 with OSK1, OSK5 and OSK20. It was also shown that P7-2, together with OSK1 and O. sativa Cullin-1, was able to form the SCF complex. Moreover, yeast two-hybrid assays revealed that P7-2 interacted with gibberellin insensitive dwarf2 (GID2 from rice and maize plants, which is essential for regulating the GA signaling pathway. It was further demonstrated that the N-terminal region of P7-2 was necessary for the interaction with GID2. Overall, these results indicated that P7-2 functioned as a component of the SCF complex in rice, and interaction of P7-2 with GID2 implied possible roles of the GA signaling pathway during RBSDV infection.

Effect of yeast storage temperature and flour composition on fermentative activities of baker's yeast

Directory of Open Access Journals (Sweden)

Pejin Dušanka J.

2009-01-01

Full Text Available Baker's yeast is a set of living cells of Saccharomyces cerevisiae. It contains around 70-72% of water, 42-45% of proteins, around 40% of carbohydrates, around 7.5% of lipids (based on dry matter, and vitamin B-complex. On the basis of yeast cell analysis it can be concluded that yeast is a complex biological system which changes in time. The intensity of the changes depends on temperature. Yeast sample was stored at 4°C i 24°C for 12 days. During storage at 4°C, the content of total carbohydrates decreased from 48.81% to 37.50% (dry matter, whereas carbohydrate loss ranged from 40.81% to 29.28% at 24°C. The content of trehalose was 12.33% in the yeast sample stored at 4°C and 0.24% at 24°C. Loss of fermentative activity was 81.76% in the sample stored at 24°C for 12 days. The composition of five samples of 1st category flour was investigated. It was found that flours containing more reducing sugars and maltose enable higher fermentation activities. The flours with higher ash content (in the range 0.5-0.94% had higher contents of phytic acid. Higher ash and phytic contents in flour increased the yeast fermentative efficiency. In bakery industry, a range of ingredients has been applied to improve the product's quality such as surface active substances (emulsifiers, enzymes, sugars and fats. In the paper, the effect of some ingredients added to dough (margarine, saccharose, sodium chloride and malted barley on the yeast fermentative activity was studied. The mentioned ingredients were added to dough at different doses: 0.5, 1.0, 1.5 and 2.0%, flour basis. It was found that the investigated ingredients affected the fermentative activity of yeast and improved the bread quality.

Using stable isotopes to monitor forms of sulfur during desulfurization processes: A quick screening method

Science.gov (United States)

Liu, Chao-Li; Hackley, Keith C.; Coleman, D.D.; Kruse, C.W.

1987-01-01

A method using stable isotope ratio analysis to monitor the reactivity of sulfur forms in coal during thermal and chemical desulfurization processes has been developed at the Illinois State Geological Survey. The method is based upon the fact that a significant difference exists in some coals between the 34S/32S ratios of the pyritic and organic sulfur. A screening method for determining the suitability of coal samples for use in isotope ratio analysis is described. Making these special coals available from coal sample programs would assist research groups in sorting out the complex sulfur chemistry which accompanies thermal and chemical processing of high sulfur coals. ?? 1987.

Lager Yeast Comes of Age

Science.gov (United States)

2014-01-01

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

The yeast genome may harbor hypoxia response elements (HRE).

Science.gov (United States)

Ferreira, Túlio César; Hertzberg, Libi; Gassmann, Max; Campos, Elida Geralda

2007-01-01

The hypoxia-inducible factor-1 (HIF-1) is a heterodimeric transcription factor activated when cells are submitted to hypoxia. The heterodimer is composed of two subunits, HIF-1alpha and the constitutively expressed HIF-1beta. During normoxia, HIF-1alpha is degraded by the 26S proteasome, but hypoxia causes HIF-1alpha to be stabilized, enter the nucleus and bind to HIF-1beta, thus forming the active complex. The complex then binds to the regulatory sequences of various genes involved in physiological and pathological processes. The specific regulatory sequence recognized by HIF-1 is the hypoxia response element (HRE) that has the consensus sequence 5'BRCGTGVBBB3'. Although the basic transcriptional regulation machinery is conserved between yeast and mammals, Saccharomyces cerevisiae does not express HIF-1 subunits. However, we hypothesized that baker's yeast has a protein analogous to HIF-1 which participates in the response to changes in oxygen levels by binding to HRE sequences. In this study we screened the yeast genome for HREs using probabilistic motif search tools. We described 24 yeast genes containing motifs with high probability of being HREs (p-value<0.1) and classified them according to biological function. Our results show that S. cerevisiae may harbor HREs and indicate that a transcription factor analogous to HIF-1 may exist in this organism.

Breeding of lager yeast with Saccharomyces cerevisiae improves stress resistance and fermentation performance.

Science.gov (United States)

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.

The role of the Parkinson's disease gene PARK9 in essential cellular pathways and the manganese homeostasis network in yeast.

Directory of Open Access Journals (Sweden)

Alessandra Chesi

Full Text Available YPK9 (Yeast PARK9; also known as YOR291W is a non-essential yeast gene predicted by sequence to encode a transmembrane P-type transport ATPase. However, its substrate specificity is unknown. Mutations in the human homolog of YPK9, ATP13A2/PARK9, have been linked to genetic forms of early onset parkinsonism. We previously described a strong genetic interaction between Ypk9 and another Parkinson's disease (PD protein α-synuclein in multiple model systems, and a role for Ypk9 in manganese detoxification in yeast. In humans, environmental exposure to toxic levels of manganese causes a syndrome similar to PD and is thus an environmental risk factor for the disease. How manganese contributes to neurodegeneration is poorly understood. Here we describe multiple genome-wide screens in yeast aimed at defining the cellular function of Ypk9 and the mechanisms by which it protects cells from manganese toxicity. In physiological conditions, we found that Ypk9 genetically interacts with essential genes involved in cellular trafficking and the cell cycle. Deletion of Ypk9 sensitizes yeast cells to exposure to excess manganese. Using a library of non-essential gene deletions, we screened for additional genes involved in tolerance to excess manganese exposure, discovering several novel pathways involved in manganese homeostasis. We defined the dependence of the deletion strain phenotypes in the presence of manganese on Ypk9, and found that Ypk9 deletion modifies the manganese tolerance of only a subset of strains. These results confirm a role for Ypk9 in manganese homeostasis and illuminates cellular pathways and biological processes in which Ypk9 likely functions.

Molecular Characterization of Yeast Strains Isolated from Different Sources by Restriction Fragment Length Polymorphism

International Nuclear Information System (INIS)

Ali, M. S.; Latif, Z.

2016-01-01

Various molecular techniques like analysis of the amplified rDNA internal transcribed spacers (ITS), intragenic spacers and total ITS region analysis by restriction fragment length polymorphism (RFLP) has been introduced for yeast identification but there are limited databases to identify yeast species on the basis of 5.8S rDNA. In this study, twenty nine yeast strains from various sources including spoiled fruits, vegetables, foodstuffs, and concentrated juices were characterized by PCR-RFLP. PCR-RFLP has been used to characterize yeasts present in different spoiled food samples after isolation of the yeasts. By using this technique, the isolated yeast strains were characterized by direct 5.8S-ITS rDNA region amplification. RFLP analysis was applied to each of the amplification products (varied from 400bp to 800bp) detected, and the corresponding yeast identifications were made according to each specific restriction patterns obtained after treatment with two endonucleases TaqI and HaeIII which yielded a specific banding pattern for each species. For further confirmation amplified products of eleven selected isolates were sequenced and blast on NCBI. Both RFLP and sequence analyses of the strains with accession nos. KF472163, KF472164, KF472165, KF472166, KF472167, KF472168, KF472169, KF472170, KF472171, KF472172, KF472173 gave significantly similar results. The isolates were found to belong five different yeast species including; Candida spp., Pichia spp., Kluyveromyces spp., Clavispora spp. and Hanseniaspora spp. This method provides a fast, easy, reliable and authentic way for determining yeast population present in different type of samples, as compared to traditional characterization technique. (author)

S-Adenosyl-L-methionine protects the probiotic yeast, Saccharomyces boulardii, from acid-induced cell death.

Science.gov (United States)

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

2013-02-13

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

Yeast strains and methods of use thereof

OpenAIRE

Goddard, Matthew Robert; Gardner, Richard Clague; Anfang, Nicole

2013-01-01

The present invention relates to yeast strains and, in particular, to yeast stains for use in fermentation processes. The invention also relates to methods of fermentation using the yeast strains of the invention either alone or in combination with other yeast strains. The invention thither relates to methods for the selection of yeast strains suitable for fermentation cultures by screening for various metabolic products and the use of specific nutrient sources.

Human eIF3b and eIF3a serve as the nucleation core for the assembly of eIF3 into two interconnected modules: the yeast-like core and the octamer

Czech Academy of Sciences Publication Activity Database

Wagner, Susan; Herrmannová, Anna; Šikrová, Darina; Valášek, Leoš Shivaya

2016-01-01

Roč. 44, č. 22 (2016), s. 10772-10788 ISSN 0305-1048 R&D Projects: GA ČR(CZ) GA14-05394S EU Projects: Wellcome Trust(GB) 090812/B/09/A Institutional support: RVO:61388971 Keywords : Human eIF3b * nucleation core * yeast -like core Subject RIV: EE - Microbiology, Virology Impact factor: 10.162, year: 2016

Membrane bioreactor wastewater treatment plants reveal diverse yeast and protist communities of potential significance in biofouling.

Science.gov (United States)

Liébana, Raquel; Arregui, Lucía; Belda, Ignacio; Gamella, Luis; Santos, Antonio; Marquina, Domingo; Serrano, Susana

2015-01-01

The yeast community was studied in a municipal full-scale membrane bioreactor wastewater treatment plant (MBR-WWTP). The unexpectedly high diversity of yeasts indicated that the activated sludge formed a suitable environment for them to proliferate, with cellular concentrations of 2.2 ± 0.8 × 10(3) CFU ml(-1). Sixteen species of seven genera were present in the biological reactor, with Ascomycetes being the most prevalent group (93%). Most isolates were able to grow in a synthetic wastewater medium, adhere to polyethylene surfaces, and develop biofilms of variable complexity. The relationship between yeast populations and the protists in the MBR-WWTP was also studied, revealing that some protist species preyed on and ingested yeasts. These results suggest that yeast populations may play a role in the food web of a WWTP and, to some extent, contribute to membrane biofouling in MBR systems.

Immobilization of yeast cells by radiation-induced polymerization

International Nuclear Information System (INIS)

Fujimura, T.; Kaetsu, I.

1982-01-01

Radiation-induced polymerization method was applied to the immobilization of yeast cells. The effects of irradiation, cooling and monomer, which are neccessary for polymerization, were recovered completely by subsequent aerobical incubation of yeast cells. The ethanol productive in immobilized yeast cells increased with the increase of aerobical incubation period. The growth of yeast cells in immobilized yeast cells was indicated. The maximum ethanol productivity in immobilized yeast cell system was around three times as much as that in free yeast cell system. (orig.)

Evolutionary History of Ascomyceteous Yeasts

Energy Technology Data Exchange (ETDEWEB)

Haridas, Sajeet; Riley, Robert; Salamov, Asaf; Goker, Markus; Klenk, Hans-Peter; Kurtzman, Cletus P.; Blackwell, Meredith; Grigoriev, Igor; Jeffries, Thomas W.

2014-06-06

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

Plasmid construction using recombination activity in the fission yeast Schizosaccharomyces pombe.

Directory of Open Access Journals (Sweden)

Ayako Chino

Full Text Available BACKGROUND: Construction of plasmids is crucial in modern genetic manipulation. As of now, the common method for constructing plasmids is to digest specific DNA sequences with restriction enzymes and to ligate the resulting DNA fragments with DNA ligase. Another potent method to construct plasmids, known as gap-repair cloning (GRC, is commonly used in the budding yeast Saccharomyces cerevisiae. GRC makes use of the homologous recombination activity that occurs within the yeast cells. Due to its flexible design and efficiency, GRC has been frequently used for constructing plasmids with complex structures as well as genome-wide plasmid collections. Although there have been reports indicating GRC feasibility in the fission yeast Schizosaccharomyces pombe, this species is not commonly used for GRC as systematic studies of reporting GRC efficiency in S. pombe have not been performed till date. METHODOLOGY/PRINCIPAL FINDINGS: We investigated GRC efficiency in S. pombe in this study. We first showed that GRC was feasible in S. pombe by constructing a plasmid that contained the LEU2 auxotrophic marker gene in vivo and showed sufficient efficiency with short homology sequences (>25 bp. No preference was shown for the sequence length from the cut site in the vector plasmid. We next showed that plasmids could be constructed in a proper way using 3 DNA fragments with 70% efficiency without any specific selections being made. The GRC efficiency with 3 DNA fragments was dramatically increased >95% in lig4Delta mutant cell, where non-homologous end joining is deficient. Following this approach, we successfully constructed plasmid vectors with leu1+, ade6+, his5+, and lys1+ markers with the low-copy stable plasmid pDblet as a backbone by applying GRC in S. pombe. CONCLUSIONS/SIGNIFICANCE: We concluded that GRC was sufficiently feasible in S. pombe for genome-wide gene functional analysis as well as for regular plasmid construction. Plasmids with different

Identification of uncommon oral yeasts from cancer patients by MALDI-TOF mass spectrometry.

Science.gov (United States)

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

2018-01-08

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

A test of the Veneziano - like πNN form factor

International Nuclear Information System (INIS)

Cass, A.; Mckellar, H.J.

1978-01-01

Dominguez' Veneziano-like πNN form factor has been investigated by attempting to use it to fit dsigma/dt data for np → pn and (antiproton)p → (antineutron)n at 8 GeV/c and 23.5 GeV/c in the interval 0 2 . With n=5/2 as proposed by Dominguez it is not possible to fit the data. A fit can be obtaine for other values of n

Stability of inorganic mercury and methylmercury on yeast-silica gel microcolumns: field sampling capabilities

Energy Technology Data Exchange (ETDEWEB)

Perez-Corona, M. [Universidad Complutense de Madrid (Spain). Dept. de Quimica Analitica

2000-11-01

The stability of methylmercury and inorganic mercury retained on yeast-silica gel microcolumns was established and compared with the stability of these species in solution. Yeast-silica gel columns with the retained analytes were stored for two months at three different temperatures: -20 C, 4 C and room temperature. At regular time intervals, both mercury species were eluted and quantified by cold vapor atomic absorption spectrometry (CVAAS). Methylmercury was found stable in the columns over the two-month period at the three different temperatures tested while the concentration of inorganic mercury decreased after one week's storage even at -20 C. These results are of great interest since the use of these microcolumns allows the preconcentration and storage of mercury species until analysis, thus saving laboratory space and avoiding the problems associated with maintaining species integrity in aqueous solution. (orig.)

Formation of In Vitro Mixed-Species Biofilms by Lactobacillus pentosus and Yeasts Isolated from Spanish-Style Green Table Olive Fermentations.

Science.gov (United States)

León-Romero, Ángela; Domínguez-Manzano, Jesús; Garrido-Fernández, Antonio; Arroyo-López, Francisco Noé; Jiménez-Díaz, Rufino

2016-01-15

The present work details the in vitro interactions between Lactobacillus pentosus and yeast strains isolated from table olive processing to form mixed biofilms. Among the different pairs assayed, the strongest biofilms were obtained from L. pentosus and Candida boidinii strain cocultures. However, biofilm formation was inhibited in the presence of d-(+)-mannose. In addition, biofilm formation by C. boidinii monoculture was stimulated in the absence of cell-cell contact with L. pentosus. Scanning electron microscopy revealed that a sort of "sticky" material formed by the yeasts contributed to substrate adherence. Hence, the data obtained in this work suggest that yeast-lactobacilli biofilms may be favored by the presence of a specific mate of yeast and L. pentosus, and that more than one mechanism might be implicated in the biofilm formation. This knowledge will help in the design of appropriate mixed starter cultures of L. pentosus-yeast species pairs that are able to improve the quality and safety of Spanish-style green table olive processing. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Sexual differentiation in fission yeast

DEFF Research Database (Denmark)

Egel, R; Nielsen, O; Weilguny, D

1990-01-01

The regulation of sexual reproduction in yeast constitutes the highest level of differentiation observed in these unicellular organisms. The various ramifications of this system involve DNA rearrangement, transcriptional control, post-translational modification (such as protein phosphorylation) a......) and receptor/signal processing. A few basic similarities are common to both fission and budding yeasts. The wiring of the regulatory circuitry, however, varies considerably between these divergent yeast groups....

Immobilization of microbial cell and yeast cell and its application to biomass conversion using radiation techniques

International Nuclear Information System (INIS)

Kaetsu, Isao; Kumakura, Minoru; Fujimura, Takashi; Kasai, Noboru; Tamada, Masao

1987-01-01

The recent results of immobilization of cellulase-producing cells and ethanol-fermentation yeast by radiation were reported. The enzyme of cellulase produced by immobilized cells was used for saccharification of lignocellulosic wastes and immobilized yeast cells were used for fermentation reaction from glucose to ethanol. The wastes such as chaff and bagasse were treated by γ-ray or electron-beam irradiation in the presence of alkali and subsequent mechanical crushing, to form a fine powder less than 50 μm in diameter. On the other hand, Trichoderma reesei as a cellulase-producing microbial cell was immobilized on a fibrous carrier having a specific porous structure and cultured to produce cellulase. The enzymatic saccharification of the pretreated waste was carried out using the produced cellulase. The enhanced fermentation process to produce ethanol from glucose with the immobilized yeast by radiation was also studied. The ethanol productivity of immobilized growing yeast cells thus obtained was thirteen times that of free yeast cells in a 1:1 volume of liquid medium to immobilized yeast cells. (author)

Immobilization of microbial cell and yeast cell and its application to biomass conversion using radiation techniques

Science.gov (United States)

Kaetsu, Isao; Kumakura, Minoru; Fujimura, Takashi; Kasai, Noboru; Tamada, Masao

The recent results of immobilization of cellulase-producing cells and ethanol-fermentation yeast by radiation were reported. The enzyme of cellulase produced by immobilized cells was used for saccharification of lignocellulosic wastes and immobilized yeast cells were used for fermentation reaction from glucose to ethanol. The wastes such as chaff and bagasse were treated by γ-ray or electron-beam irradiation in the presence of alkali and subsequent mechanical crushing, to form a fine powder less than 50 μm in diameter. On the other hand, Trichoderma reesei as a cellulase-producing microbial cell was immobilized on a fibrous carrier having a specific porous structure and cultured to produce cellulase. The enzymatic saccharification of the pretreated waste was carried out using the produced cellulase. The enhanced fermentation process to produce ethanol from glucose with the immobilized yeast by radiation was also studied. The ethanol productivity of immobilized growing yeast cells thus obtained was thirteen times that of free yeast cells in a 1:1 volume of liquid medium to immobilized yeast cells.

Characterization of polymethyl methacrylate/polyethylene glycol/aluminum nitride composite as form-stable phase change material prepared by in situ polymerization method

International Nuclear Information System (INIS)

Zhang, Lei; Zhu, Jiaoqun; Zhou, Weibin; Wang, Jun; Wang, Yan

2011-01-01

Highlights: → Form-stable PMMA/PEG/AlN PCMs were prepared by in situ polymerization method. → AlN additive effectively enhanced the heat transfer property of composite PCMs. → The composites exhibited desirable thermal performance and electric insulativity. → The composites were available for the thermal management of electronic device. - Abstract: This work was focused on the preparation and characterization of a new type of form-stable phase change material (PCM) employed in thermal management. Using the method of in situ polymerization, polyethylene glycol (PEG) acting as the PCM and aluminum nitride (AlN) serving as the thermal conductivity promoter were uniformly encapsulated and embedded inside the three-dimensional network structure of PMMA matrix. When the mass fraction of PEG was below 70%, the prepared composite PCMs remained solid without leakage above the melting point of the PEG. XRD and FT-IR results indicated that the PEG was physically combined with PMMA matrix and AlN additive and did not participate in the polymerization. Thermal analysis results showed that the prepared composite PCMs possess available latent heat capacity and thermal stability, and the AlN additive was able to effectively enhance the heat transfer property of organic PCM. Moreover, the volume resistivity of composite achieved (5.92 ± 0.16) x 10 10 Ω cm when the mass ratio of AlN was 30%. To sum up, the prepared form-stable PCMs were competent for the thermal management of electronic device due to their acceptable thermal performance and electric insulativity.

Induction and evaluation of mutations for improved protein production in certain species of yeasts in the Philippines

International Nuclear Information System (INIS)

Borromeo, J.D.

1976-02-01

The species of yeasts included in the studies are Saccharomyces cerevisiae, Rhodeterula rubra, Rhodeterula pilimane and those isolated from fruits such as citrus, papaya and banana. Part of the project involved induction of sporulation to obtain haploid cells for crossing to produce stable disploids exhibiting improved protein production. Although S. cerevisiae produce less protein than Rhodeterula, it produces ascesperes which are haploid cells. These haploid cells can be used to obtain stable diploids with the desirable characteristics by crossing cultures. Rhodeterula, a fungus that does not produce ascesperes will be subjected to certain adverse conditions to induce, hopefully, sperulation

Occurrence of Killer Yeast Strains in Fruit and Berry Wine Yeast Populations

Directory of Open Access Journals (Sweden)

Gintare Gulbiniene

2004-01-01

Full Text Available Apple, cranberry, chokeberry and Lithuanian red grape wine yeast populations were used for the determination of killer yeast occurrence. According to the tests of the killer characteristics and immunity the isolated strains were divided into seven groups. In this work the activity of killer toxins purified from some typical strains was evaluated. The analysed strains produced different amounts of active killer toxin and some of them possessed new industrially significant killer properties. Total dsRNA extractions in 11 killer strains of yeast isolated from spontaneous fermentations revealed that the molecular basis of the killer phenomenon was not only dsRNAs, but also unidentified genetic determinants.

The diversity, extracellular enzymatic activities and photoprotective compounds of yeasts isolated in Antarctica

Directory of Open Access Journals (Sweden)

Aline B. M Vaz

2011-09-01

Full Text Available The diversity of yeasts collected from different sites in Antarctica (Admiralty Bay, King George Island and Port Foster Bay and Deception Island and their ability to produce extracellular enzymes and mycosporines were studied. Samples were collected during the austral summer season, between November 2006 and January 2007, from the rhizosphere of Deschampsia antarctica, ornithogenic (penguin guano soil, soil, marine and lake sediments, marine water and freshwater from lakes. A total of 89 isolates belonging to the following genera were recovered: Bensingtonia, Candida, Cryptococcus, Debaryomyces, Dioszegia, Exophiala, Filobasidium, Issatchenkia (Pichia, Kodamaea, Leucosporidium, Leucosporidiella, Metschnikowia, Nadsonia, Pichia, Rhodotorula, and Sporidiobolus, and the yeast-like fungi Aureobasidium, Leuconeurospora and Microglossum. Cryptococcus victoriae was the most frequently identified species. Several species isolated in our study have been previously reported to be Antarctic psychophilic yeasts, including Cr. antarcticus, Cr. victoriae, Dioszegia hungarica and Leucosporidium scottii. The cosmopolitan yeast species A. pullulans, C. zeylanoides, D. hansenii, I. orientalis, K. ohmeri, P. guilliermondii, Rh. mucilaginosa, and S. salmonicolor were also isolated. Five possible new species were identified. Sixty percent of the yeasts had at least one detectable extracellular enzymatic activity. Cryptococcus antarcticus, D. aurantiaca, D. crocea, D. hungarica, Dioszegia sp., E. xenobiotica, Rh. glaciales, Rh. laryngis, Microglossum sp. 1 and Microglossum sp. 2 produced mycosporines. Of the yeast isolates, 41.7% produced pigments and/or mycosporines and could be considered adapted to survive in Antarctica. Most of the yeasts had extracellular enzymatic activities at 4ºC and 20ºC, indicating that they could be metabolically active in the sampled substrates.

Potential of high pressure homogenization to induce autolysis of wine yeasts.

Science.gov (United States)

Comuzzo, Piergiorgio; Calligaris, Sonia; Iacumin, Lucilla; Ginaldi, Federica; Palacios Paz, Anthony Efrain; Zironi, Roberto

2015-10-15

High pressure homogenization (HPH) was tested for inducing autolysis in a commercial strain of Saccharomyces bayanus for winemaking. The effects on cell viability, the release of soluble proteins, glucidic colloids and amino acids in wine-like medium and the volatile composition of the autolysates were investigated after processing, in comparison with thermolysis. HPH seemed a promising technique for inducing autolysis of wine yeasts. One pass at 150 MPa was the best operating conditions. Soluble colloids, proteins and free amino acids were similar after HPH and thermolysis, but the former gave a more interesting volatile composition after processing, with higher concentrations of ethyl esters (fruity odors) and lower fatty acids (potential off-flavors). This might allow different winemaking applications for HPH, such as the production of yeast derivatives for wine ageing. In the conditions tested, HPH did not allow the complete inactivation of yeast cells; the treatment shall be optimized before winemaking use. Copyright © 2015 Elsevier Ltd. All rights reserved.

Methods for Synchronization and Analysis of the Budding Yeast Cell Cycle.

Science.gov (United States)

Rosebrock, Adam P

2017-01-03

Like other eukaryotes, budding yeast temporally separate cell growth and division. DNA synthesis is distinct from chromosome segregation. Storage carbohydrates are accumulated slowly and then rapidly liquidated once per cycle. Cyclin-dependent kinase associates with multiple different transcriptionally and posttranslationally regulated cyclins to drive the cell cycle. These and other crucial events of cellular growth and division are limited to narrow windows of the cell cycle. Many experiments in the yeast laboratory treat a culture of cells as a homogeneous mixture. Measurements of asynchronous cultures are, however, confounded by the presence of cells in various cell cycle stages; measuring a population average in unsynchronized cells provides at best a decreased signal and at worst an artifactual result. A number of experimentally tractable methods have been developed to generate populations of yeast cells that are synchronized with respect to cell cycle phase. Robust methods for determining cell cycle position have also been developed. These methods are introduced here. © 2017 Cold Spring Harbor Laboratory Press.

Biomedical applications of yeast- a patent view, part one: yeasts as workhorses for the production of therapeutics and vaccines.

Science.gov (United States)

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

2017-08-01

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

Identification of human ferritin, heavy polypeptide 1 (FTH1) and yeast RGI1 (YER067W) as pro-survival sequences that counteract the effects of Bax and copper in Saccharomyces cerevisiae

Energy Technology Data Exchange (ETDEWEB)

Eid, Rawan [Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario (Canada); Department of Biology, Queen' s University, Kingston, Ontario (Canada); Boucher, Eric [Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec (Canada); Gharib, Nada [Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario (Canada); Khoury, Chamel [Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario (Canada); Department of Biology, Queen' s University, Kingston, Ontario (Canada); Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec (Canada); Arab, Nagla T.T. [Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario (Canada); Department of Biology, Queen' s University, Kingston, Ontario (Canada); Murray, Alistair [Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec (Canada); Young, Paul G. [Department of Biology, Queen' s University, Kingston, Ontario (Canada); Mandato, Craig A. [Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec (Canada); Greenwood, Michael T., E-mail: michael.greenwood@rmc.ca [Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario (Canada)

2016-03-01

Ferritin is a sub-family of iron binding proteins that form multi-subunit nanotype iron storage structures and prevent oxidative stress induced apoptosis. Here we describe the identification and characterization of human ferritin, heavy polypeptide 1 (FTH1) as a suppressor of the pro-apoptotic murine Bax sequence in yeast. In addition we demonstrate that FTH1 is a general pro-survival sequence since it also prevents the cell death inducing effects of copper when heterologously expressed in yeast. Although ferritins are phylogenetically widely distributed and are present in most species of Bacteria, Archaea and Eukarya, ferritin is conspicuously absent in most fungal species including Saccharomyces cerevisiae. An in silico analysis of the yeast proteome lead to the identification of the 161 residue RGI1 (YER067W) encoded protein as a candidate for being a yeast ferritin. In addition to sharing 20% sequence identity with the 183 residue FTH1, RGI1 also has similar pro-survival properties as ferritin when overexpressed in yeast. Analysis of recombinant protein by SDS-PAGE and by electron microscopy revealed the expected formation of higher-order structures for FTH1 that was not observed with Rgi1p. Further analysis revealed that cells overexpressing RGI1 do not show increased resistance to iron toxicity and do not have enhanced capacity to store iron. In contrast, cells lacking RGI1 were found to be hypersensitive to the toxic effects of iron. Overall, our results suggest that Rgi1p is a novel pro-survival protein whose function is not related to ferritin but nevertheless it may have a role in regulating yeast sensitivity to iron stress. - Highlights: • Human ferritin, heavy polypeptide 1 (FTH1) was identified as a suppressor of the pro-apoptotic Bax in yeast. • Based on its similarity to ferritin we examined Rgi1p/YER067W for potential ferritin like functions. • Like human H-ferritin, RGI1 confers increased resistance to apoptotic inducing stresses in yeast. �

Identification of human ferritin, heavy polypeptide 1 (FTH1) and yeast RGI1 (YER067W) as pro-survival sequences that counteract the effects of Bax and copper in Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Eid, Rawan; Boucher, Eric; Gharib, Nada; Khoury, Chamel; Arab, Nagla T.T.; Murray, Alistair; Young, Paul G.; Mandato, Craig A.; Greenwood, Michael T.

2016-01-01

Ferritin is a sub-family of iron binding proteins that form multi-subunit nanotype iron storage structures and prevent oxidative stress induced apoptosis. Here we describe the identification and characterization of human ferritin, heavy polypeptide 1 (FTH1) as a suppressor of the pro-apoptotic murine Bax sequence in yeast. In addition we demonstrate that FTH1 is a general pro-survival sequence since it also prevents the cell death inducing effects of copper when heterologously expressed in yeast. Although ferritins are phylogenetically widely distributed and are present in most species of Bacteria, Archaea and Eukarya, ferritin is conspicuously absent in most fungal species including Saccharomyces cerevisiae. An in silico analysis of the yeast proteome lead to the identification of the 161 residue RGI1 (YER067W) encoded protein as a candidate for being a yeast ferritin. In addition to sharing 20% sequence identity with the 183 residue FTH1, RGI1 also has similar pro-survival properties as ferritin when overexpressed in yeast. Analysis of recombinant protein by SDS-PAGE and by electron microscopy revealed the expected formation of higher-order structures for FTH1 that was not observed with Rgi1p. Further analysis revealed that cells overexpressing RGI1 do not show increased resistance to iron toxicity and do not have enhanced capacity to store iron. In contrast, cells lacking RGI1 were found to be hypersensitive to the toxic effects of iron. Overall, our results suggest that Rgi1p is a novel pro-survival protein whose function is not related to ferritin but nevertheless it may have a role in regulating yeast sensitivity to iron stress. - Highlights: • Human ferritin, heavy polypeptide 1 (FTH1) was identified as a suppressor of the pro-apoptotic Bax in yeast. • Based on its similarity to ferritin we examined Rgi1p/YER067W for potential ferritin like functions. • Like human H-ferritin, RGI1 confers increased resistance to apoptotic inducing stresses in yeast. �

The function of yeast CAP family proteins in lipid export, mating, and pathogen defense.

Science.gov (United States)

Darwiche, Rabih; El Atab, Ola; Cottier, Stéphanie; Schneiter, Roger

2018-04-01

In their natural habitat, yeast cells are constantly challenged by changing environmental conditions and a fierce competition for limiting resources. To thrive under such conditions, cells need to adapt and divide quickly, and be able to neutralize the toxic compounds secreted by their neighbors. Proteins like the pathogen-related yeast, Pry proteins, which belong to the large CAP/SCP/TAPS superfamily, may have an important role in this function. CAP proteins are conserved from yeast to man and are characterized by a unique αβα sandwich fold. They are mostly secreted glycoproteins and have been implicated in many different physiological processes including pathogen defense, virulence, venom toxicity, and sperm maturation. Yeast members of this family bind and export sterols as well as fatty acids, and they render cells resistant to eugenol, an antimicrobial compound present in clove oil. CAP family members might thus exert their various physiological functions through binding, sequestration, and neutralization of such small hydrophobic compounds. © 2017 Federation of European Biochemical Societies.

Recreating the synthesis of starch granules in yeast

Science.gov (United States)

Pfister, Barbara; Sánchez-Ferrer, Antoni; Diaz, Ana; Lu, Kuanjen; Otto, Caroline; Holler, Mirko; Shaik, Farooque Razvi; Meier, Florence; Mezzenga, Raffaele; Zeeman, Samuel C

2016-01-01

Starch, as the major nutritional component of our staple crops and a feedstock for industry, is a vital plant product. It is composed of glucose polymers that form massive semi-crystalline granules. Its precise structure and composition determine its functionality and thus applications; however, there is no versatile model system allowing the relationships between the biosynthetic apparatus, glucan structure and properties to be explored. Here, we expressed the core Arabidopsis starch-biosynthesis pathway in Saccharomyces cerevisiae purged of its endogenous glycogen-metabolic enzymes. Systematic variation of the set of biosynthetic enzymes illustrated how each affects glucan structure and solubility. Expression of the complete set resulted in dense, insoluble granules with a starch-like semi-crystalline organization, demonstrating that this system indeed simulates starch biosynthesis. Thus, the yeast system has the potential to accelerate starch research and help create a holistic understanding of starch granule biosynthesis, providing a basis for the targeted biotechnological improvement of crops. DOI: http://dx.doi.org/10.7554/eLife.15552.001 PMID:27871361

Fault tolerance in protein interaction networks: stable bipartite subgraphs and redundant pathways.

Science.gov (United States)

Brady, Arthur; Maxwell, Kyle; Daniels, Noah; Cowen, Lenore J

2009-01-01

As increasing amounts of high-throughput data for the yeast interactome become available, more system-wide properties are uncovered. One interesting question concerns the fault tolerance of protein interaction networks: whether there exist alternative pathways that can perform some required function if a gene essential to the main mechanism is defective, absent or suppressed. A signature pattern for redundant pathways is the BPM (between-pathway model) motif, introduced by Kelley and Ideker. Past methods proposed to search the yeast interactome for BPM motifs have had several important limitations. First, they have been driven heuristically by local greedy searches, which can lead to the inclusion of extra genes that may not belong in the motif; second, they have been validated solely by functional coherence of the putative pathways using GO enrichment, making it difficult to evaluate putative BPMs in the absence of already known biological annotation. We introduce stable bipartite subgraphs, and show they form a clean and efficient way of generating meaningful BPMs which naturally discard extra genes included by local greedy methods. We show by GO enrichment measures that our BPM set outperforms previous work, covering more known complexes and functional pathways. Perhaps most importantly, since our BPMs are initially generated by examining the genetic-interaction network only, the location of edges in the protein-protein physical interaction network can then be used to statistically validate each candidate BPM, even with sparse GO annotation (or none at all). We uncover some interesting biological examples of previously unknown putative redundant pathways in such areas as vesicle-mediated transport and DNA repair.

A prolonged chronological lifespan is an unexpected benefit of the [PSI+] prion in yeast.

Science.gov (United States)

Wang, Kai; Melki, Ronald; Kabani, Mehdi

2017-01-01

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

Polyglutamine toxicity in yeast induces metabolic alterations and mitochondrial defects

KAUST Repository

Papsdorf, Katharina

2015-09-03

Background Protein aggregation and its pathological effects are the major cause of several neurodegenerative diseases. In Huntington’s disease an elongated stretch of polyglutamines within the protein Huntingtin leads to increased aggregation propensity. This induces cellular defects, culminating in neuronal loss, but the connection between aggregation and toxicity remains to be established. Results To uncover cellular pathways relevant for intoxication we used genome-wide analyses in a yeast model system and identify fourteen genes that, if deleted, result in higher polyglutamine toxicity. Several of these genes, like UGO1, ATP15 and NFU1 encode mitochondrial proteins, implying that a challenged mitochondrial system may become dysfunctional during polyglutamine intoxication. We further employed microarrays to decipher the transcriptional response upon polyglutamine intoxication, which exposes an upregulation of genes involved in sulfur and iron metabolism and mitochondrial Fe-S cluster formation. Indeed, we find that in vivo iron concentrations are misbalanced and observe a reduction in the activity of the prominent Fe-S cluster containing protein aconitase. Like in other yeast strains with impaired mitochondria, non-fermentative growth is impossible after intoxication with the polyglutamine protein. NMR-based metabolic analyses reveal that mitochondrial metabolism is reduced, leading to accumulation of metabolic intermediates in polyglutamine-intoxicated cells. Conclusion These data show that damages to the mitochondrial system occur in polyglutamine intoxicated yeast cells and suggest an intricate connection between polyglutamine-induced toxicity, mitochondrial functionality and iron homeostasis in this model system.

Virgin olive oil yeasts: A review.

Science.gov (United States)

Ciafardini, Gino; Zullo, Biagi Angelo

2018-04-01

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

Regulatory mechanism of the flavoprotein Tah18-dependent nitric oxide synthesis and cell death in yeast.

Science.gov (United States)

Yoshikawa, Yuki; Nasuno, Ryo; Kawahara, Nobuhiro; Nishimura, Akira; Watanabe, Daisuke; Takagi, Hiroshi

2016-07-01

Nitric oxide (NO) is a ubiquitous signaling molecule involved in the regulation of a large number of cellular functions. The regulatory mechanism of NO generation in unicellular eukaryotic yeast cells is poorly understood due to the lack of mammalian and bacterial NO synthase (NOS) orthologues, even though yeast produces NO under oxidative stress conditions. Recently, we reported that the flavoprotein Tah18, which was previously shown to transfer electrons to the iron-sulfur cluster protein Dre2, is involved in NOS-like activity in the yeast Saccharomyces cerevisiae. On the other hand, Tah18 was reported to promote apoptotic cell death after exposure to hydrogen peroxide (H2O2). Here, we showed that NOS-like activity requiring Tah18 induced cell death upon treatment with H2O2. Our experimental results also indicate that Tah18-dependent NO production and cell death are suppressed by enhancement of the interaction between Tah18 and its molecular partner Dre2. Our findings indicate that the Tah18-Dre2 complex regulates cell death as a molecular switch via Tah18-dependent NOS-like activity in response to environmental changes. Copyright © 2016 Elsevier Inc. All rights reserved.

Acidic and uncharged polar residues in the consensus motifs of the yeast Ca2+ transporter Gdt1p are required for calcium transport.

Science.gov (United States)

Colinet, Anne-Sophie; Thines, Louise; Deschamps, Antoine; Flémal, Gaëlle; Demaegd, Didier; Morsomme, Pierre

2017-07-01

The UPF0016 family is a recently identified group of poorly characterized membrane proteins whose function is conserved through evolution and that are defined by the presence of 1 or 2 copies of the E-φ-G-D-[KR]-[TS] consensus motif in their transmembrane domain. We showed that 2 members of this family, the human TMEM165 and the budding yeast Gdt1p, are functionally related and are likely to form a new group of Ca 2+ transporters. Mutations in TMEM165 have been demonstrated to cause a new type of rare human genetic diseases denominated as Congenital Disorders of Glycosylation. Using site-directed mutagenesis, we generated 17 mutations in the yeast Golgi-localized Ca 2+ transporter Gdt1p. Single alanine substitutions were targeted to the highly conserved consensus motifs, 4 acidic residues localized in the central cytosolic loop, and the arginine at position 71. The mutants were screened in a yeast strain devoid of both the endogenous Gdt1p exchanger and Pmr1p, the Ca 2+ -ATPase of the Golgi apparatus. We show here that acidic and polar uncharged residues of the consensus motifs play a crucial role in calcium tolerance and calcium transport activity and are therefore likely to be architectural components of the cation binding site of Gdt1p. Importantly, we confirm the essential role of the E53 residue whose mutation in humans triggers congenital disorders of glycosylation. © 2017 John Wiley & Sons Ltd.

Development of form stable Poly(methyl methacrylate) (PMMA) coated thermal phase change material for solar water heater applications

Science.gov (United States)

Munusamy, Y.; Shanmugam, S.; Shi-Ying, Kee

2018-04-01

Phase change material (PCM) is one of the most popular and widely used thermal energy storage material in solar water heater because it able to absorb and release a large amount of latent heat during a phase change process over a narrow temperature range. However the practical application of PCM is limited by two major issues; 1) leakage which leads to material loss and corrosion of tank and 2) large volume change during phase change process which cause pressure build up in the tank. In this work, form-stable PCM was prepared by coating myristic acid with Poly(methyl methacrylate) (PMMA) to prevent leakage of PCM. PMMA was mixed with different weight percentage (0.1, 0.2, 0.3, 0.4 and 0.5 wt%) of dicumyl peroxide (DCP). The purpose of adding DCP to PMMA is to crosslink the polymer and to increase the mechanical strength of PMMA to hold the myristic acid content inside the coating during the phase change process. Leakage test results showed that PMMA mixed with 0.1% DCP exhibit 0% leakage. This result is further supported by Field Emission Scanning Electron Microscopy (FESEM) images and Fourier transform infrared spectroscopy (FTIR) analysis results, where a compact and uniform coating without cracks were formed for PCM coated with PMMA with 0.1% DCP. Differential scanning calorimetry (DSC) results shows that the melting point of form-stable PCM is 55°C, freezing point is 50°C, the latent heat of melting and freezing is 67.59 J/g.

Terroir of yeasts? – Application of FTIR spectroscopy and molecular methods for strain typing of yeasts

Directory of Open Access Journals (Sweden)

Gerhards Daniel

2015-01-01

Full Text Available The site specific influence on wine (Terroir is an often by wine producers, consumers and scientists discussed topic in the world of wine. A study on grapes and (spontaneous fermentations from six different vineyards was done to investigate the biodiversity of yeasts and to answer the question if there is a terroir of yeast and how it could be influenced. Randomly isolated yeasts were identified by FTIR-spectroscopy and molecular methods on species and strain level. Vineyard specific yeast floras would be observed but they are not such important as expected. Only a few overlapping strain patterns would be identified during both vintages. The yeast flora of the winery had a huge impact on the spontaneous fermentations, but is not really constant and influenced by different factors from outside.

The Yeast Saccharomyces cerevisiae as a Model for Understanding RAS Proteins and Their Role in Human Tumorigenesis

Science.gov (United States)

Cazzanelli, Giulia; Francisco, Rita; Azevedo, Luísa; Carvalho, Patrícia Dias; Almeida, Ana; Côrte-Real, Manuela; Oliveira, Maria José; Lucas, Cândida; Sousa, Maria João

2018-01-01

The exploitation of the yeast Saccharomyces cerevisiae as a biological model for the investigation of complex molecular processes conserved in multicellular organisms, such as humans, has allowed fundamental biological discoveries. When comparing yeast and human proteins, it is clear that both amino acid sequences and protein functions are often very well conserved. One example of the high degree of conservation between human and yeast proteins is highlighted by the members of the RAS family. Indeed, the study of the signaling pathways regulated by RAS in yeast cells led to the discovery of properties that were often found interchangeable with RAS proto-oncogenes in human pathways, and vice versa. In this work, we performed an updated critical literature review on human and yeast RAS pathways, specifically highlighting the similarities and differences between them. Moreover, we emphasized the contribution of studying yeast RAS pathways for the understanding of human RAS and how this model organism can contribute to unveil the roles of RAS oncoproteins in the regulation of mechanisms important in the tumorigenic process, like autophagy. PMID:29463063

21 CFR 184.1983 - Bakers yeast extract.

Science.gov (United States)

2010-04-01

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

Identification of salivary components that induce transition of hyphae to yeast in Candida albicans

NARCIS (Netherlands)

Leito, J.T.D.; Ligtenberg, A.J.M.; Nazmi, K.; Veerman, E.C.I.

2009-01-01

Candida albicans, the major human fungal pathogen, undergoes a reversible morphological transition from single yeast cells to pseudohyphae and hyphae filaments. The hyphae form is considered the most invasive form of the fungus. The purpose of this study is to investigate the effect of saliva on

Screening and evaluation of the glucoside hydrolase activity in Saccharomyces and Brettanomyces brewing yeasts.

Science.gov (United States)

Daenen, L; Saison, D; Sterckx, F; Delvaux, F R; Verachtert, H; Derdelinckx, G

2008-02-01

The aim of this study was to select and examine Saccharomyces and Brettanomyces brewing yeasts for hydrolase activity towards glycosidically bound volatile compounds. A screening for glucoside hydrolase activity of 58 brewing yeasts belonging to the genera Saccharomyces and Brettanomyces was performed. The studied Saccharomyces brewing yeasts did not show 1,4-beta-glucosidase activity, but a strain dependent beta-glucanase activity was observed. Some Brettanomyces species did show 1,4-beta-glucosidase activity. The highest constitutive activity was found in Brettanomyces custersii. For the most interesting strains the substrate specificity was studied and their activity was evaluated in fermentation experiments with added hop glycosides. Fermentations with Br. custersii led to the highest release of aglycones. Pronounced exo-beta-glucanase activity in Saccharomyces brewing yeasts leads to a higher release of certain aglycones. Certain Brettanomyces brewing yeasts, however, are more interesting for hydrolysis of glycosidically bound volatiles of hops. The release of flavour active compounds from hop glycosides opens perspectives for the bioflavouring and product diversification of beverages like beer. The release can be enhanced by using Saccharomyces strains with high exo-beta-glucanase activity. Higher activities can be found in Brettanomyces species with beta-glucosidase activity.

Study on polyethylene glycol/epoxy resin composite as a form-stable phase change material

International Nuclear Information System (INIS)

Fang Yutang; Kang Huiying; Wang Weilong; Liu Hong; Gao Xuenong

2010-01-01

Form-stable polyethylene glycol (PEG)/epoxy resin (EP) composite as a novel phase change material (PCM) was prepared using casting molding method. In this new material, PEG acts as the latent heat storage material and EP polymer serves as the supporting material, which provides structural strength and prevents the leakage of the melted PEG. The structure and morphology of the novel composite were observed using Fourier transformation infrared spectroscope (FTIR) and scanning electronic microscope (SEM). The thermo-mechanical property and transition behavior were characterized by polarizing optical microscope (POM), static thermo-mechanical analysis (TMA) and differential scanning calorimeter (DSC). The experimental results show that, as a result of the physical tangled function of the epoxy resin carrier to the PEG segment, the composite macroscopically presents the solid-solid phase change characteristic.

Correlation between microstructure and mechanical properties of stable mixtures formed by austenite and martensite

International Nuclear Information System (INIS)

Eckstein, C.B.

1982-03-01

The influence of martensite in mechanical properties of stable mixtures formed by austenite and martensite was studied by varying the amount of martensite in the mixtures. Microstructural parameters were determined by Optical Quantitative Metallography and used to establish the correlation between the mechanical response of the mixtures in tension and their microstructures. The 'in situ' deformation of each phase in mixtures was determined experimentally in terms of the rule of mixtures. It is shown that the partitioning of the deformation depends on the amount of martensite in the mixture and that it tends to a condition of isostrain at higher martensite volume fractions. Optical observation of fractured specimens showed that the beginning of the fracture process may related to regions of the austenite grain boundaries where they meet martensite plates. (Author) [pt

Endoplasmic reticulum involvement in yeast cell death

International Nuclear Information System (INIS)

Nicanor Austriaco, O.

2012-01-01

Yeast cells undergo programed cell death (PCD) with characteristic markers associated with apoptosis in mammalian cells including chromatin breakage, nuclear fragmentation, reactive oxygen species generation, and metacaspase activation. Though significant research has focused on mitochondrial involvement in this phenomenon, more recent work with both Saccharomyces cerevisiae and Schizosaccharomyces pombe has also implicated the endoplasmic reticulum (ER) in yeast PCD. This minireview provides an overview of ER stress-associated cell death (ER-SAD) in yeast. It begins with a description of ER structure and function in yeast before moving to a discussion of ER-SAD in both mammalian and yeast cells. Three examples of yeast cell death associated with the ER will be highlighted here including inositol starvation, lipid toxicity, and the inhibition of N-glycosylation. It closes by suggesting ways to further examine the involvement of the ER in yeast cell death.

Reconstructing the regulatory circuit of cell fate determination in yeast mating response.

Science.gov (United States)

Shao, Bin; Yuan, Haiyu; Zhang, Rongfei; Wang, Xuan; Zhang, Shuwen; Ouyang, Qi; Hao, Nan; Luo, Chunxiong

2017-07-01

Massive technological advances enabled high-throughput measurements of proteomic changes in biological processes. However, retrieving biological insights from large-scale protein dynamics data remains a challenging task. Here we used the mating differentiation in yeast Saccharomyces cerevisiae as a model and developed integrated experimental and computational approaches to analyze the proteomic dynamics during the process of cell fate determination. When exposed to a high dose of mating pheromone, the yeast cell undergoes growth arrest and forms a shmoo-like morphology; however, at intermediate doses, chemotropic elongated growth is initialized. To understand the gene regulatory networks that control this differentiation switch, we employed a high-throughput microfluidic imaging system that allows real-time and simultaneous measurements of cell growth and protein expression. Using kinetic modeling of protein dynamics, we classified the stimulus-dependent changes in protein abundance into two sources: global changes due to physiological alterations and gene-specific changes. A quantitative framework was proposed to decouple gene-specific regulatory modes from the growth-dependent global modulation of protein abundance. Based on the temporal patterns of gene-specific regulation, we established the network architectures underlying distinct cell fates using a reverse engineering method and uncovered the dose-dependent rewiring of gene regulatory network during mating differentiation. Furthermore, our results suggested a potential crosstalk between the pheromone response pathway and the target of rapamycin (TOR)-regulated ribosomal biogenesis pathway, which might underlie a cell differentiation switch in yeast mating response. In summary, our modeling approach addresses the distinct impacts of the global and gene-specific regulation on the control of protein dynamics and provides new insights into the mechanisms of cell fate determination. We anticipate that our

Yeast-assisted synthesis of polypyrrole: Quantification and influence on the mechanical properties of the cell wall.

Science.gov (United States)

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

2018-04-01

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

Synthesis of polypyrrole within the cell wall of yeast by redox-cycling of [Fe(CN)6](3-)/[Fe(CN)6](4-).

Science.gov (United States)

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

2016-02-01

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

A world review of fungi, yeasts, and slime molds in caves

Directory of Open Access Journals (Sweden)

McAlpine Donald F.

2013-01-01

Full Text Available We provide a review of fungi, yeasts, and slime molds that have been found in natural solution caves and mines worldwide. Such habitats provide frequent roost sites for bats, and in eastern North America the environmental conditions that support white-nose syndrome, a lethal fungal disease currently devastating bat populations. A list of 1029 species of fungi, slime moulds, and yeasts in 518 genera have been documented from caves and mines worldwide in 225 articles. Ascomycota dominate the cave environment. Most research has been conducted in temperate climates, especially in Europe. A mean of 17.9±24.4SD fungal species are reported per study. Questions remain about the origin and ecological roles of fungi in caves, and which, if any, are cave-specialists. In the northern hemisphere, caves are generally characterized by relatively stable, low temperatures and a lack of organic substrates. This environment favors communities of oligotrophic, psychrotolerant fungi. Data that may help explain how cave environmental features and faunas inf luence the introduction and transmission of cave fungi remains scant.

History of genome editing in yeast.

Science.gov (United States)

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

2018-05-01

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

Nectar-living yeasts of a tropical host plant community: diversity and effects on community-wide floral nectar traits

Science.gov (United States)

2017-01-01

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

Nectar-living yeasts of a tropical host plant community: diversity and effects on community-wide floral nectar traits

Directory of Open Access Journals (Sweden)

Azucena Canto

2017-07-01

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

Effect of increased yeast alcohol acetyltransferase activity on flavor profiles of wine and distillates.

Science.gov (United States)

Lilly, M; Lambrechts, M G; Pretorius, I S

2000-02-01

The distinctive flavor of wine, brandy, and other grape-derived alcoholic beverages is affected by many compounds, including esters produced during alcoholic fermentation. The characteristic fruity odors of the fermentation bouquet are primarily due to a mixture of hexyl acetate, ethyl caproate (apple-like aroma), iso-amyl acetate (banana-like aroma), ethyl caprylate (apple-like aroma), and 2-phenylethyl acetate (fruity, flowery flavor with a honey note). The objective of this study was to investigate the feasibility of improving the aroma of wine and distillates by overexpressing one of the endogenous yeast genes that controls acetate ester production during fermentation. The synthesis of acetate esters by the wine yeast Saccharomyces cerevisiae during fermentation is ascribed to at least three acetyltransferase activities, namely, alcohol acetyltransferase (AAT), ethanol acetyltransferase, and iso-amyl AAT. To investigate the effect of increased AAT activity on the sensory quality of Chenin blanc wines and distillates from Colombar base wines, we have overexpressed the alcohol acetyltransferase gene (ATF1) of S. cerevisiae. The ATF1 gene, located on chromosome XV, was cloned from a widely used commercial wine yeast strain of S. cerevisiae, VIN13, and placed under the control of the constitutive yeast phosphoglycerate kinase gene (PGK1) promoter and terminator. Chromoblot analysis confirmed the integration of the modified copy of ATF1 into the genome of three commercial wine yeast strains (VIN7, VIN13, and WE228). Northern blot analysis indicated constitutive expression of ATF1 at high levels in these yeast transformants. The levels of ethyl acetate, iso-amyl acetate, and 2-phenylethyl acetate increased 3- to 10-fold, 3.8- to 12-fold, and 2- to 10-fold, respectively, depending on the fermentation temperature, cultivar, and yeast strain used. The concentrations of ethyl caprate, ethyl caprylate, and hexyl acetate only showed minor changes, whereas the acetic acid

21 CFR 172.898 - Bakers yeast glycan.

Science.gov (United States)

2010-04-01

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

The wine and beer yeast Dekkera bruxellensis.

Science.gov (United States)

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

2014-09-01

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

Biotechnology of non-Saccharomyces yeasts-the basidiomycetes.

Science.gov (United States)

Johnson, Eric A

2013-09-01

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

Measurement of the bio-availability in man of a pharmaceutic form of magnesium, by the means of stable isotopes

International Nuclear Information System (INIS)

Benech, H.; Pruvost, A.; Grognet, J.M.; Morge, X.

1994-01-01

A method for measuring the absolute bio-availability, in man, of an oral magnesium pharmaceutic form by the means of the simultaneous utilization of two stable magnesium isotopes, 25 Mg and 26 Mg, by oral or intra-venous administrations in order to study the metabolism of magnesium in the human body, is presented. Fecal elimination and urinary excretion of magnesium are recorded. 10 refs

Screening of intact yeasts and cell extracts to reduce Scrapie prions during biotransformation of food waste.

Science.gov (United States)

Huyben, David; Boqvist, Sofia; Passoth, Volkmar; Renström, Lena; Allard Bengtsson, Ulrika; Andréoletti, Olivier; Kiessling, Anders; Lundh, Torbjörn; Vågsholm, Ivar

2018-02-08

Yeasts can be used to convert organic food wastes to protein-rich animal feed in order to recapture nutrients. However, the reuse of animal-derived waste poses a risk for the transmission of infectious prions that can cause neurodegeneration and fatality in humans and animals. The aim of this study was to investigate the ability of yeasts to reduce prion activity during the biotransformation of waste substrates-thereby becoming a biosafety hurdle in such a circular food system. During pre-screening, 30 yeast isolates were spiked with Classical Scrapie prions and incubated for 72 h in casein substrate, as a waste substitute. Based on reduced Scrapie seeding activity, waste biotransformation and protease activities, intact cells and cell extracts of 10 yeasts were further tested. Prion analysis showed that five yeast species reduced Scrapie seeding activity by approximately 1 log10 or 90%. Cryptococcus laurentii showed the most potential to reduce prion activity since both intact and extracted cells reduced Scrapie by 1 log10 and achieved the highest protease activity. These results show that select forms of yeast can act as a prion hurdle during the biotransformation of waste. However, the limited ability of yeasts to reduce prion activity warrants caution as a sole barrier to transmission as higher log reductions are needed before using waste-cultured yeast in circular food systems.

Facile synthesis of high-temperature (1000 °C) phase-stable rice-like anatase TiO{sub 2} nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Lv, Lizhen [Capital Normal University, Beijing Key Laboratory for Optical Materials and Photonic Devices, Department of Chemistry (China); Chen, Qirong [Beijing Center for Physical and Chemical Analysis (BCPCA) (China); Liu, Xiuyun; Wang, Miaomiao; Meng, Xiangfu, E-mail: xfmeng@cnu.edu.cn [Capital Normal University, Beijing Key Laboratory for Optical Materials and Photonic Devices, Department of Chemistry (China)

2015-05-15

High-temperature phase-stable rice-like anatase TiO{sub 2} nanocrystals were synthesized by one-pot solvothermal method using soluble titania xerogel and isopropyl alcohol (IPA) as the precursor and the solvent, respectively. Sample characterization was carried out by powder X-ray diffraction, high-resolution transmission electron microscopy, field emission scanning electron microscope, X-ray photoelectron spectroscopy, and N{sub 2} adsorption–desorption isotherms. The results showed that TiO{sub 2} nanocrystals had rice-like shapes with an average size of 5 nm in width and 35 nm in length. The BET surface area was 153 m{sup 2}/g. Unexpectedly, the rice-like TiO{sub 2} nanocrystals exhibited high-temperature phase stability, which could remain as pure anatase phase after calcinations at 1000 °C. Growth mechanism investigation revealed that the IPA solvent played a key role in nucleation and growth of rice-like anatase TiO{sub 2} nanocrystals. The photodegradation of rhodamine B demonstrated that rice-like anatase TiO{sub 2} nanocrystals exhibited enhanced photocatalytic activity under visible light irradiation.

Cell organisation, sulphur metabolism and ion transport-related genes are differentially expressed in Paracoccidioides brasiliensis mycelium and yeast cells

Directory of Open Access Journals (Sweden)

Passos Geraldo AS

2006-08-01

Full Text Available Abstract Background Mycelium-to-yeast transition in the human host is essential for pathogenicity by the fungus Paracoccidioides brasiliensis and both cell types are therefore critical to the establishment of paracoccidioidomycosis (PCM, a systemic mycosis endemic to Latin America. The infected population is of about 10 million individuals, 2% of whom will eventually develop the disease. Previously, transcriptome analysis of mycelium and yeast cells resulted in the assembly of 6,022 sequence groups. Gene expression analysis, using both in silico EST subtraction and cDNA microarray, revealed genes that were differential to yeast or mycelium, and we discussed those involved in sugar metabolism. To advance our understanding of molecular mechanisms of dimorphic transition, we performed an extended analysis of gene expression profiles using the methods mentioned above. Results In this work, continuous data mining revealed 66 new differentially expressed sequences that were MIPS(Munich Information Center for Protein Sequences-categorised according to the cellular process in which they are presumably involved. Two well represented classes were chosen for further analysis: (i control of cell organisation – cell wall, membrane and cytoskeleton, whose representatives were hex (encoding for a hexagonal peroxisome protein, bgl (encoding for a 1,3-β-glucosidase in mycelium cells; and ags (an α-1,3-glucan synthase, cda (a chitin deacetylase and vrp (a verprolin in yeast cells; (ii ion metabolism and transport – two genes putatively implicated in ion transport were confirmed to be highly expressed in mycelium cells – isc and ktp, respectively an iron-sulphur cluster-like protein and a cation transporter; and a putative P-type cation pump (pct in yeast. Also, several enzymes from the cysteine de novo biosynthesis pathway were shown to be up regulated in the yeast form, including ATP sulphurylase, APS kinase and also PAPS reductase. Conclusion Taken

Herbicide glufosinate inhibits yeast growth and extends longevity during wine fermentation.

Science.gov (United States)

Vallejo, Beatriz; Picazo, Cecilia; Orozco, Helena; Matallana, Emilia; Aranda, Agustín

2017-09-29

Glufosinate ammonium (GA) is a widely used herbicide that inhibits glutamine synthetase. This inhibition leads to internal amino acid starvation which, in turn, causes the activation of different nutrient sensing pathways. GA also inhibits the enzyme of the yeast Saccharomyces cerevisiae in such a way that, although it is not used as a fungicide, it may alter yeast performance in industrial processes like winemaking. We describe herein how GA indeed inhibits the yeast growth of a wine strain during the fermentation of grape juice. In turn, GA extends longevity in a variety of growth media. The biochemical analysis indicates that GA partially inhibits the nutrient sensing TORC1 pathway, which may explain these phenotypes. The GCN2 kinase mutant is hypersensitive to GA. Hence the control of translation and amino acid biosynthesis is required to also deal with the damaging effects of this pesticide. A global metabolomics analysis under winemaking conditions indicated that an increase in amino acid and in polyamines occurred. In conclusion, GA affects many different biochemical processes during winemaking, which provides us with some insights into both the effect of this herbicide on yeast physiology and into the relevance of the metabolic step for connecting nitrogen and carbon metabolism.

Effect of sweet yeast bread formula on evaluating rapid mix test

Directory of Open Access Journals (Sweden)

Petra Dvořáková

2011-01-01

Full Text Available The aim of this work was to detect how different sweet yeast bread formulas influence results of rapid mix test and by the help of sensory analysis to discover consumer preferences and possible benefit and use in bakery industry. Applied raw materials (ground wheat flour T 530, yeast, sugar, salt, oil, egg, improver Hit along with basic formula were taken from the Varmužova bakery in Boršice by Buchlovice. The basic formula served as a standard (I, other six formulas were then determined (II–VII. In each formula, the rate of yeast, sugar or oil was altered in the range of ± 10% compared with the standard. Flour bread-making quality – Hagberg Falling number [s], Sedimentation index [ml], wet gluten [%], ash [%], moisture [%], binding capacity [%], granulation [%], alveographic energy [10−4J] and alveographic rate P/L – was measured. Rapid mix test and parameters like pastry weight, volume, shape, dough yield, pastry yield, baking loss, penetration and sensory analysis were determined. To establish yeast fermentation activity, Engelke fermentation test was applied. The most evident differences among the samples appeared in the volume and shape. The results of sensory analysis showed that the samples with higher rate of altered raw materials were evaluated as the best.

Effect of dietary supplementation with selenium-enriched yeast or sodium selenite on ruminal enzyme activities and blood chemistry in sheep

Directory of Open Access Journals (Sweden)

Zita Faixová

2016-01-01

Full Text Available The experiment was conducted to evaluate the effect of feeding a diet supplemented with different forms of selenium on the rumen fluid, blood and serum enzyme activity and osmotic fragility of red blood cells in sheep. The experiment was carried out on 18 sheep of the Valashka breed at the age of 18 months, divided into 3 groups. The first group was given basal diet (BD with a Se content of 0.17 mg/kg of dry matter (DM. The second group received BD supplemented with 0.4 mg Se/kg of (DM in the form of sodium selenite. The third group received BD supplemented with 0.4 mg Se/kg of (DM in the form of Se-yeast extract. Duration of the trial was 12 weeks. Selenium concentration in blood and total rumen fluid were elevated in both supplemented groups with the highest values in Se-yeast-treated sheep. Blood glutathione peroxidase (GPx activity was significantly increased, regardless of the source of selenium. Osmotic resistance of red blood cells was not affected by selenium supplementation. The results indicate that feeding a diet supplemented with selenium from Se-yeast or selenite improved selenium status in blood and total rumen fluid. Selenium from sodium selenite was as effective as selenium from Se-yeast in the availability of selenium for the blood GPx activity. The effect of selenium supplementation on the ruminal enzyme activity depends on the selenium form; GGT and GDH were significantly higher in the Se-yeast supplement group, AST and ALP were significantly higher in the selenite supplement group.

Between science and industry-applied yeast research.

Science.gov (United States)

Korhola, Matti

2018-03-01

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

On some hypersurfaces with time like normal bundle in pseudo Riemannian space forms

International Nuclear Information System (INIS)

Kashani, S.M.B.

1995-12-01

In this work we classify immersed hypersurfaces with constant sectional curvature in pseudo Riemannian space forms if the normal bundle is time like and the mean curvature is constant. (author). 9 refs

Structural and functional characterization of recombinant napin-like protein of Momordica charantia expressed in methylotrophic yeast Pichia pastoris.

Science.gov (United States)

Yadav, Shailesh Kumar R; Sahu, Tejram; Dixit, Aparna

2016-08-01

Napin and napin-like proteins belong to the 2S albumin seed storage family of proteins and have been shown to display a variety of biological activities. However, due to a high degree of polymorphism, purification of a single napin or napin-like protein exhibiting biological activity is extremely difficult. In the present study, we have produced the napin-like protein of Momordica charantia using the methylotrophic Pichia pastoris expression system. The recombinant napin-like protein (rMcnapin) secreted in the extracellular culture supernatant was enriched by ammonium sulfate precipitation, and purified using size exclusion chromatography at a yield of ∼290 mg/L of culture. Secondary structure analysis of the purified rMcnapin revealed it to be predominantly α-helical with minimal β strand content. CD spectroscopic and fluorescence spectroscopic analyses revealed the rMcnapin to be stable at a wide range of temperatures and pH. The rMcnapin exhibited antifungal activity against Trichoderma viride with an IC50 of ∼3.7 μg/ml and trypsin inhibitor activity with an IC50 of 4.2 μM. Thus, large amounts of homogenous preparations of the biologically active rMcnapin could be obtained at shake flask level, which is otherwise difficult from its natural source.

Plasma spraying method for forming diamond and diamond-like coatings

Science.gov (United States)

Holcombe, Cressie E.; Seals, Roland D.; Price, R. Eugene

1997-01-01

A method and composition for the deposition of a thick layer (10) of diamond or diamond-like material. The method includes high temperature processing wherein a selected composition (12) including at least glassy carbon is heated in a direct current plasma arc device to a selected temperature above the softening point, in an inert atmosphere, and is propelled to quickly quenched on a selected substrate (20). The softened or molten composition (18) crystallizes on the substrate (20) to form a thick deposition layer (10) comprising at least a diamond or diamond-like material. The selected composition (12) includes at least glassy carbon as a primary constituent (14) and may include at least one secondary constituent (16). Preferably, the secondary constituents (16) are selected from the group consisting of at least diamond powder, boron carbide (B.sub.4 C) powder and mixtures thereof.

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

Directory of Open Access Journals (Sweden)

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.

Yeast-based biosensors: design and applications.

Science.gov (United States)

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

2015-02-01

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

One small step for a yeast--microevolution within macrophages renders Candida glabrata hypervirulent due to a single point mutation.

Directory of Open Access Journals (Sweden)

Sascha Brunke

2014-10-01

Full Text Available Candida glabrata is one of the most common causes of candidemia, a life-threatening, systemic fungal infection, and is surpassed in frequency only by Candida albicans. Major factors contributing to the success of this opportunistic pathogen include its ability to readily acquire resistance to antifungals and to colonize and adapt to many different niches in the human body. Here we addressed the flexibility and adaptability of C. glabrata during interaction with macrophages with a serial passage approach. Continuous co-incubation of C. glabrata with a murine macrophage cell line for over six months resulted in a striking alteration in fungal morphology: The growth form changed from typical spherical yeasts to pseudohyphae-like structures - a phenotype which was stable over several generations without any selective pressure. Transmission electron microscopy and FACS analyses showed that the filamentous-like morphology was accompanied by changes in cell wall architecture. This altered growth form permitted faster escape from macrophages and increased damage of macrophages. In addition, the evolved strain (Evo showed transiently increased virulence in a systemic mouse infection model, which correlated with increased organ-specific fungal burden and inflammatory response (TNFα and IL-6 in the brain. Similarly, the Evo mutant significantly increased TNFα production in the brain on day 2, which is mirrored in macrophages confronted with the Evo mutant, but not with the parental wild type. Whole genome sequencing of the Evo strain, genetic analyses, targeted gene disruption and a reverse microevolution experiment revealed a single nucleotide exchange in the chitin synthase-encoding CHS2 gene as the sole basis for this phenotypic alteration. A targeted CHS2 mutant with the same SNP showed similar phenotypes as the Evo strain under all experimental conditions tested. These results indicate that microevolutionary processes in host-simulative conditions

A closed form for the electrostatic interaction between two rod-like charged objects

International Nuclear Information System (INIS)

Askari, M; Abouie, J

2011-01-01

We have calculated the electrostatic interaction between two rod-like charged objects with arbitrary orientations in three dimensions. We obtained a closed-form formula expressing the interaction energy in terms of the separation distance between the centers of the two rod-like objects, r, their lengths (denoted by 2l 1 and 2l 2 ) and their relative orientations (indicated by θ and φ). When the objects have the same length (2l 1 = 2l 2 = l), for particular values of separations, i.e. for r ≤ 0.8l, two types of minimum appear in the interaction energy with respect to θ. By employing the closed-form formula and introducing a scaled temperature t, we have also studied the thermodynamic properties of a 1D system of rod-like charged objects. For different separation distances, the dependence of the specific heat of the system to the scaled temperature has been studied. It is found that, for r < 0.8l, the specific heat has a maximum.

Evolution of the hemiascomycete yeasts: on life styles and the importance of inbreeding.

Science.gov (United States)

Knop, Michael

2006-07-01

The term 'breeding system' is used to describe the morphological and behavioural aspects of the sexual life cycle of a species. The yeast breeding system provides three alternatives that enable hapoids to return to the diploid state that is necessary for meiosis: mating of unrelated haploids (amphimixis), mating between spores from the same tetrad (intratetrad mating, automixis) and mother daughter mating upon mating type switching (haplo-selfing). The frequency of specific mating events affects the level of heterozygosity present in individuals and the genetic diversity of populations. This review discusses the reproductive strategies of yeasts, in particular S. cerevisiae (Bakers' or budding yeast). Emphasis is put on intratetrad mating, its implication for diversity, and how the particular genome structure could have evolved to ensure the preservation of a high degree of heterozygosity in conjunction with frequent intratetrad matings. I also discuss how the ability of yeast to control the number of spores that are formed accounts for high intratetrad mating rates and for enhanced transmission of genomic variation. I extend the discussion to natural genetic variation and propose that a high level of plasticity is inherent in the yeast breeding system, which may allow variation of the breeding behaviour in accordance with the needs imposed by the environment. (c) 2006 Wiley Periodicals, Inc.

Prevalence of candida and non-candida yeasts isolated from patients with yeast fungal infections in Tehran labs

Directory of Open Access Journals (Sweden)

Hashemi SJ

2011-04-01

Full Text Available "n 800x600 Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} Background: Infections caused by opportunistic yeasts such as Candida species, Trichosporon, Rhodotorula and Saccharomyces have increased in immunocompromis-ed patients and their identification is crucial as intrinsic and acquired resistance of some yeast species to antifungal agents are on the rise. The aim of this study was to identify the organisms to the species level in order to suggest accurate and effective antifungal therapies."n"nMethods: In this study that carried out in Tehran, Iran in 2009, 200 patients with yeast infection were medically examined and clinical specimens were prepared for direct examination and culture on Sabouraud dextrose agar. Subsequently, the isolated yeast colonies were identified using various tests including culture on Corn Meal agar with Tween 80, CHROMagar Candida and casein agar. For the definite identification of organisms some biochemical tests were done based on carbohydrate assimilation by RapID Yeast Plus System kit, and, finally, a molecular method, PCR-RFLP, using Hpa II enzyme, was performed for the remaining unknown yeast species."n"nResults: A total of 211 yeast isolates were identified in 200 patients with yeast infections. The most frequent isolated yeasts were Candida albicans, 124 (58.77%, followed by Candida parapsilosis, 36 (17.06%, Candida tropicalis, 17 (8.06%, Candida glabrata, 13 (6.16%, Candida krusei, 8 (3.79%, Candida guilliermondii, 2 (0.96%, Trichosporon, 3 (1.14%, Rhodotorula, 1 (0.47%, Saccaromyces cerevisiae, 1 (0.47% and other

Oral yeast colonization throughout pregnancy.

Science.gov (United States)

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

2017-03-01

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

Genomic and Phenotypic Characterization of Yeast Biosensor for Deep-space Radiation

Science.gov (United States)

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

2016-01-01

The BioSentinel mission was selected to launch as a secondary payload onboard NASA Exploration Mission 1 (EM-1) in 2018. In BioSentinel, the budding yeast Saccharomyces cerevisiae will be used as a biosensor to measure the long-term impact of deep-space radiation to living organisms. In the 4U-payload, desiccated yeast cells from different strains will be stored inside microfluidic cards equipped with 3-color LED optical detection system to monitor cell growth and metabolic activity. At different times throughout the 12-month mission, these cards will be filled with liquid yeast growth media to rehydrate and grow the desiccated cells. The growth and metabolic rates of wild-type and radiation-sensitive strains in deep-space radiation environment will be compared to the rates measured in the ground- and microgravity-control units. These rates will also be correlated with measurements obtained from onboard physical dosimeters. In our preliminary long-term desiccation study, we found that air-drying yeast cells in 10% trehalose is the best method of cell preservation in order to survive the entire 18-month mission duration (6-month pre-launch plus 12-month full-mission periods). However, our study also revealed that desiccated yeast cells have decreasing viability over time when stored in payload-like environment. This suggests that the yeast biosensor will have different population of cells at different time points during the long-term mission. In this study, we are characterizing genomic and phenotypic changes in our yeast biosensor due to long-term storage and desiccation. For each yeast strain that will be part of the biosensor, several clones were reisolated after long-term storage by desiccation. These clones were compared to their respective original isolate in terms of genomic composition, desiccation tolerance and radiation sensitivity. Interestingly, clones from a radiation-sensitive mutant have better desiccation tolerance compared to their original isolate

Electron transport chain in a thermotolerant yeast.

Science.gov (United States)

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

2017-04-01

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

BH3-only protein Bim inhibits activity of antiapoptotic members of Bcl-2 family when expressed in yeast.

Science.gov (United States)

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

2011-09-02

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

Supplementary Material for: Polyglutamine toxicity in yeast induces metabolic alterations and mitochondrial defects

KAUST Repository

Papsdorf, Katharina; Kaiser, Christoph; Drazic, Adrian; Grö tzinger, Stefan W.; Haeß ner, Carmen; Eisenreich, Wolfgang; Richter, Klaus

2015-01-01

-S cluster formation. Indeed, we find that in vivo iron concentrations are misbalanced and observe a reduction in the activity of the prominent Fe-S cluster containing protein aconitase. Like in other yeast strains with impaired mitochondria, non-fermentative

A prolonged chronological lifespan is an unexpected benefit of the [PSI+] prion in yeast.

Directory of Open Access Journals (Sweden)

Kai Wang

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

Interactions between Drosophila and its natural yeast symbionts-Is Saccharomyces cerevisiae a good model for studying the fly-yeast relationship?

Science.gov (United States)

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

Biomodification of edible fats and oils by yeasts; Kobo ni yoru shokuyo yushi no seibutsugakuteki kaishitsu

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, K.; Endo, Y. [Tohoku University, Sendai (Japan). Faculty of Agriculture

1995-10-20

Lipid-biomodification ability was examined for yeasts isolated from soil using culture medium containing beef tallow (2%). Some yeasts, e.g. Candida, Trichosporon and Rhodotorula species were able to grow on fats and oils. Fatty acid and triacylglycerol compositions were modified in lipids of some strains. Candida sp. MIS-1 and YM1-1 preferentially produced oleic acid. Candida sp. MIS-1 had high level of triacylglycerol with a melting point like olive oil. Fatty acid composition of lipids in Candida lipolytica IAM4948 and Rhodotorula sp. AO3-5 was similar to that of cacao butter. Yeast oils obtained from C. lipolytica provided the melting characterization different from beef tallow. 30 refs., 3 figs., 7 tabs.

Nanoscale domain formation of phosphatidylinositol 4-phosphate in the plasma and vacuolar membranes of living yeast cells.

Science.gov (United States)

Tomioku, Kan-Na; Shigekuni, Mikiko; Hayashi, Hiroki; Yoshida, Akane; Futagami, Taiki; Tamaki, Hisanori; Tanabe, Kenji; Fujita, Akikazu

2018-05-01

In budding yeast Saccharomyces cerevisiae, PtdIns(4)P serves as an essential signalling molecule in the Golgi complex, endosomal system, and plasma membrane, where it is involved in the control of multiple cellular functions via direct interactions with PtdIns(4)P-binding proteins. To analyse the distribution of PtdIns(4)P in yeast cells at a nanoscale level, we employed an electron microscopy technique that specifically labels PtdIns(4)P on the freeze-fracture replica of the yeast membrane. This method minimizes the possibility of artificial perturbation, because molecules in the membrane are physically immobilised in situ. We observed that PtdIns(4)P is localised on the cytoplasmic leaflet, but not the exoplasmic leaflet, of the plasma membrane, Golgi body, vacuole, and vesicular structure membranes. PtdIns(4)P labelling was not observed in the membrane of the endoplasmic reticulum, and in the outer and inner membranes of the nuclear envelope or mitochondria. PtdIns(4)P forms clusters of plasma membrane and vacuolar membrane according to point pattern analysis of immunogold labelling. There are three kinds of compartments in the cytoplasmic leaflet of the plasma membrane. In the present study, we showed that PtdIns(4)P is specifically localised in the flat undifferentiated plasma membrane compartment. In the vacuolar membrane, PtdIns(4)P was concentrated in intramembrane particle (IMP)-deficient raft-like domains, which are tightly bound to lipid droplets, but not surrounding IMP-rich non-raft domains in geometrical IMP-distributed patterns in the stationary phase. This is the first report showing microdomain formations of PtdIns(4)P in the plasma membrane and vacuolar membrane of budding yeast cells at a nanoscale level, which will illuminate the functionality of PtdIns(4)P in each membrane. Copyright © 2018 Elsevier GmbH. All rights reserved.

Studying anti-oxidative properties of inclusion complexes of α-lipoic acid with γ-cyclodextrin in single living fission yeast by confocal Raman microspectroscopy

Science.gov (United States)

Noothalapati, Hemanth; Ikarashi, Ryo; Iwasaki, Keita; Nishida, Tatsuro; Kaino, Tomohiro; Yoshikiyo, Keisuke; Terao, Keiji; Nakata, Daisuke; Ikuta, Naoko; Ando, Masahiro; Hamaguchi, Hiro-o.; Kawamukai, Makoto; Yamamoto, Tatsuyuki

2018-05-01

α-lipoic acid (ALA) is an essential cofactor for many enzyme complexes in aerobic metabolism, especially in mitochondria of eukaryotic cells where respiration takes place. It also has excellent anti-oxidative properties. The acid has two stereo-isomers, R- and S- lipoic acid (R-LA and S-LA), but only the R-LA has biological significance and is exclusively produced in our body. A mutant strain of fission yeast, Δdps1, cannot synthesize coenzyme Q10, which is essential during yeast respiration, leading to oxidative stress. Therefore, it shows growth delay in the minimal medium. We studied anti-oxidant properties of ALA in its free form and their inclusion complexes with γ-cyclodextrin using this mutant yeast model. Both free forms R- and S-LA as well as 1:1 inclusion complexes with γ-cyclodextrin recovered growth of Δdps1 depending on the concentration and form. However, it has no effect on the growth of wild type fission yeast strain at all. Raman microspectroscopy was employed to understand the anti-oxidant property at the molecular level. A sensitive Raman band at 1602 cm-1 was monitored with and without addition of ALAs. It was found that 0.5 mM and 1.0 mM concentrations of ALAs had similar effect in both free and inclusion forms. At 2.5 mM ALAs, free forms inhibited the growth while inclusion complexes helped in recovered. 5.0 mM ALA showed inhibitory effect irrespective of form. Our results suggest that the Raman band at 1602 cm-1 is a good measure of oxidative stress in fission yeast.

Characterization of pectinase activity for enology from yeasts occurring in Argentine Bonarda grape

Science.gov (United States)

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

2015-01-01

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

Full Data of Yeast Interacting Proteins Database (Original Version) - Yeast Interacting Proteins Database | LSDB Archive [Life Science Database Archive metadata

Lifescience Database Archive (English)

Full Text Available List Contact us Yeast Interacting Proteins Database Full Data of Yeast Interacting Proteins Database (Origin...al Version) Data detail Data name Full Data of Yeast Interacting Proteins Database (Original Version) DOI 10....18908/lsdba.nbdc00742-004 Description of data contents The entire data in the Yeast Interacting Proteins Database...eir interactions are required. Several sources including YPD (Yeast Proteome Database, Costanzo, M. C., Hoga...ematic name in the SGD (Saccharomyces Genome Database; http://www.yeastgenome.org /). Bait gene name The gen

DNA mutations mediate microevolution between host-adapted forms of the pathogenic fungus Cryptococcus neoformans.

Directory of Open Access Journals (Sweden)

Denise A Magditch

Full Text Available The disease cryptococcosis, caused by the fungus Cryptococcus neoformans, is acquired directly from environmental exposure rather than transmitted person-to-person. One explanation for the pathogenicity of this species is that interactions with environmental predators select for virulence. However, co-incubation of C. neoformans with amoeba can cause a "switch" from the normal yeast morphology to a pseudohyphal form, enabling fungi to survive exposure to amoeba, yet conversely reducing virulence in mammalian models of cryptococcosis. Like other human pathogenic fungi, C. neoformans is capable of microevolutionary changes that influence the biology of the organism and outcome of the host-pathogen interaction. A yeast-pseudohyphal phenotypic switch also happens under in vitro conditions. Here, we demonstrate that this morphological switch, rather than being under epigenetic control, is controlled by DNA mutation since all pseudohyphal strains bear mutations within genes encoding components of the RAM pathway. High rates of isolation of pseudohyphal strains can be explained by the physical size of RAM pathway genes and a hypermutator phenotype of the strain used in phenotypic switching studies. Reversion to wild type yeast morphology in vitro or within a mammalian host can occur through different mechanisms, with one being counter-acting mutations. Infection of mice with RAM mutants reveals several outcomes: clearance of the infection, asymptomatic maintenance of the strains, or reversion to wild type forms and progression of disease. These findings demonstrate a key role of mutation events in microevolution to modulate the ability of a fungal pathogen to cause disease.

Identification of SUMO conjugation sites in the budding yeast proteome

Directory of Open Access Journals (Sweden)

Miguel Esteras

2017-10-01

Full Text Available Post-translational modification by the small ubiquitin-like modifier (SUMO is an important mechanism regulating protein function. Identification of SUMO conjugation sites on substrates is a challenging task. Here we employed a proteomic method to map SUMO acceptor lysines in budding yeast proteins. We report the identification of 257 lysine residues where SUMO is potentially attached. Amongst the hits, we identified already known SUMO substrates and sites, confirming the success of the approach. In addition, we tested several of the novel substrates using SUMO immunoprecipitation analysis and confirmed that the SUMO acceptor lysines identified in these proteins are indeed bona fide SUMOylation sites. We believe that the collection of SUMO sites presented here is an important resource for future functional studies of SUMOylation in yeast.

Fission yeast cells undergo nuclear division in the absence of spindle microtubules.

Directory of Open Access Journals (Sweden)

Stefania Castagnetti

2010-10-01

Full Text Available Mitosis in eukaryotic cells employs spindle microtubules to drive accurate chromosome segregation at cell division. Cells lacking spindle microtubules arrest in mitosis due to a spindle checkpoint that delays mitotic progression until all chromosomes have achieved stable bipolar attachment to spindle microtubules. In fission yeast, mitosis occurs within an intact nuclear membrane with the mitotic spindle elongating between the spindle pole bodies. We show here that in fission yeast interference with mitotic spindle formation delays mitosis only briefly and cells proceed to an unusual nuclear division process we term nuclear fission, during which cells perform some chromosome segregation and efficiently enter S-phase of the next cell cycle. Nuclear fission is blocked if spindle pole body maturation or sister chromatid separation cannot take place or if actin polymerization is inhibited. We suggest that this process exhibits vestiges of a primitive nuclear division process independent of spindle microtubules, possibly reflecting an evolutionary intermediate state between bacterial and Archeal chromosome segregation where the nucleoid divides without a spindle and a microtubule spindle-based eukaryotic mitosis.

Preferential inclusion of extrachromosomal genetic elements in yeast meiotic spores.

Science.gov (United States)

Brewer, B J; Fangman, W L

1980-09-01

During meiosis and sporulation in the yeast Saccharomyces cerevisiae, extrachromosomal traits are efficiently transmitted to haploid spores. Although the pattern of inheritance of chromosomal traits reflects the mechanism of regular chromosomal segregation in meiosis, it is not known what processes are reflected by the efficient inheritance of extrachromosomal traits. Because extrachromosomal genetic elements in yeast are present in multiple copies, perpetuation of an extrachromosomal trait could occur by the passive envelopment of a subset of copies or by an active sequestering of all or a subset of copies within the four spores. We show that only subsets of the four extrachromosomal nucleic acids commonly found in yeast are transmitted through meiosis--55% of mitochondrial DNA copies, 82% of the 2-micron DNA plasmids, and about 70% of the L and M double-stranded RNAs. However, electron micrographs of serial sections through yeast asci indicate that the four spore enclose only 30% of the total ascus material. Thus these extrachromosomal elements are preferentially included within the spores, indicating that their inheritance is not a random process. Transmission of mitochondrial DNA can be accounted for by the observed enclosure of 52% of the mitochondrial volume within the spores. The high transmission frequencies of the double-stranded RNAs (which exist as virus-like particles in the cytoplasm) and 2-micron DNA must indicate that either these nucleic acids are actively recruited from the cytoplasm by some mechanism or they are associated in some way with the nucleus during meiosis.

How does yeast respond to pressure?

Directory of Open Access Journals (Sweden)

Fernandes P.M.B.

2005-01-01

Full Text Available The brewing and baking yeast Saccharomyces cerevisiae has been used as a model for stress response studies of eukaryotic cells. In this review we focus on the effect of high hydrostatic pressure (HHP on S. cerevisiae. HHP exerts a broad effect on yeast cells characteristic of common stresses, mainly associated with protein alteration and lipid bilayer phase transition. Like most stresses, pressure induces cell cycle arrest. Below 50 MPa (500 atm yeast cell morphology is unaffected whereas above 220 MPa wild-type cells are killed. S. cerevisiae cells can acquire barotolerance if they are pretreated with a sublethal stress due to temperature, ethanol, hydrogen peroxide, or pressure. Nevertheless, pressure only leads to protection against severe stress if, after pressure pretreatment, the cells are also re-incubated at room pressure. We attribute this effect to the inhibition of the protein synthesis apparatus under HHP. The global genome expression analysis of S. cerevisiae cells submitted to HHP revealed a stress response profile. The majority of the up-regulated genes are involved in stress defense and carbohydrate metabolism while most repressed genes belong to the cell cycle progression and protein synthesis categories. However, the signaling pathway involved in the pressure response is still to be elucidated. Nitric oxide, a signaling molecule involved in the regulation of a large number of cellular functions, confers baroprotection. Furthermore, S. cerevisiae cells in the early exponential phase submitted to 50-MPa pressure show induction of the expression level of the nitric oxide synthase inducible isoform. As pressure becomes an important biotechnological tool, studies concerning this kind of stress in microorganisms are imperative.

Yeasts preservation: alternatives for lyophilisation

OpenAIRE

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

2012-01-01

The aim of the study was to compare the effect of two low-cost, low technology traditional methods for drying starter cultures with standard lyophilisation. Lyophilised yeast cultures and yeast cultures preserved in dry rice cakes and dry plant fibre strands were examined for viable cell counts during 6 months storage at 4 and 25 °C. None of the yeast cultures showed a significant loss in viable cell count during 6 months of storage at 4 °C upon lyophilisation and preservation in dry rice cak...

Succinic acid production by Actinobacillus succinogenes using hydrolysates of spent yeast cells and corn fiber.

Science.gov (United States)

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

2011-01-01

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

Yeasts Diversity in Fermented Foods and Beverages

Science.gov (United States)

Tamang, Jyoti Prakash; Fleet, Graham H.

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

Manipulation of culture conditions alters lipid content and fatty acid profiles of a wide variety of known and new oleaginous yeasts species

Science.gov (United States)

Sitepu, Irnayuli R.; Sestric, Ryan; Ignatia, Laura; Levin, David; German, J. Bruce; Gillies, Laura A.; Almada, Luis A.G.; Boundy-Mills, Kyria L.

2013-01-01

Oleaginous yeasts have been studied for oleochemical production for over 80 years. Only a few species have been studied intensely. To expand the diversity of oleaginous yeasts available for lipid research, we surveyed a broad diversity of yeasts with indicators of oleaginicity including known oleaginous clades, and buoyancy. Sixty-nine strains representing 17 genera and 50 species were screened for lipid production. Yeasts belonged to Ascomycota families, Basidiomycota orders, and the yeast-like algal genus Prototheca. Total intracellular lipids and fatty acid composition were determined under different incubation times and nitrogen availability. Thirteen new oleaginous yeast species were discovered, representing multiple ascomycete and basidiomycete clades. Nitrogen starvation generally increased intracellular lipid content. The fatty acid profiles varied with the growth conditions regardless of taxonomic affiliation. The dominant fatty acids were oleic acid, palmitic acid, linoleic acid, and stearic acid. Yeasts and culture conditions that produced fatty acids appropriate for biodiesel were identified. PMID:23891835

Manipulation of culture conditions alters lipid content and fatty acid profiles of a wide variety of known and new oleaginous yeast species.

Science.gov (United States)

Sitepu, Irnayuli R; Sestric, Ryan; Ignatia, Laura; Levin, David; German, J Bruce; Gillies, Laura A; Almada, Luis A G; Boundy-Mills, Kyria L

2013-09-01

Oleaginous yeasts have been studied for oleochemical production for over 80 years. Only a few species have been studied intensely. To expand the diversity of oleaginous yeasts available for lipid research, we surveyed a broad diversity of yeasts with indicators of oleaginicity including known oleaginous clades, and buoyancy. Sixty-nine strains representing 17 genera and 50 species were screened for lipid production. Yeasts belonged to Ascomycota families, Basidiomycota orders, and the yeast-like algal genus Prototheca. Total intracellular lipids and fatty acid composition were determined under different incubation times and nitrogen availability. Thirteen new oleaginous yeast species were discovered, representing multiple ascomycete and basidiomycete clades. Nitrogen starvation generally increased intracellular lipid content. The fatty acid profiles varied with the growth conditions regardless of taxonomic affiliation. The dominant fatty acids were oleic acid, palmitic acid, linoleic acid, and stearic acid. Yeasts and culture conditions that produced fatty acids appropriate for biodiesel were identified. Copyright © 2013 Elsevier Ltd. All rights reserved.

Fault tolerance in protein interaction networks: stable bipartite subgraphs and redundant pathways.

Directory of Open Access Journals (Sweden)

Arthur Brady

Full Text Available As increasing amounts of high-throughput data for the yeast interactome become available, more system-wide properties are uncovered. One interesting question concerns the fault tolerance of protein interaction networks: whether there exist alternative pathways that can perform some required function if a gene essential to the main mechanism is defective, absent or suppressed. A signature pattern for redundant pathways is the BPM (between-pathway model motif, introduced by Kelley and Ideker. Past methods proposed to search the yeast interactome for BPM motifs have had several important limitations. First, they have been driven heuristically by local greedy searches, which can lead to the inclusion of extra genes that may not belong in the motif; second, they have been validated solely by functional coherence of the putative pathways using GO enrichment, making it difficult to evaluate putative BPMs in the absence of already known biological annotation. We introduce stable bipartite subgraphs, and show they form a clean and efficient way of generating meaningful BPMs which naturally discard extra genes included by local greedy methods. We show by GO enrichment measures that our BPM set outperforms previous work, covering more known complexes and functional pathways. Perhaps most importantly, since our BPMs are initially generated by examining the genetic-interaction network only, the location of edges in the protein-protein physical interaction network can then be used to statistically validate each candidate BPM, even with sparse GO annotation (or none at all. We uncover some interesting biological examples of previously unknown putative redundant pathways in such areas as vesicle-mediated transport and DNA repair.

Genetics of Yeasts

Science.gov (United States)

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

The use of yeasts in biotechnology processes dates back to ancient days. Before 7000 BC, beer was produced in Sumeria. Wine was made in Assyria in 3500 BC, and ancient Rome had over 250 bakeries, which were making leavened bread by 100 BC. And milk has been made into Kefyr and Koumiss in Asia for many centuries (Demain, Phaff, & Kurtzman, 1999). However, the importance of yeast in the food and beverage industries was only realized about 1860, when their role in food manufacturing became evident.

Screening for new brewing yeasts in the non-Saccharomyces sector with Torulaspora delbrueckii as model.

Science.gov (United States)

Michel, Maximilian; Kopecká, Jana; Meier-Dörnberg, Tim; Zarnkow, Martin; Jacob, Fritz; Hutzler, Mathias

2016-04-01

This study describes a screening system for future brewing yeasts focusing on non-Saccharomyces yeasts. The aim was to find new yeast strains that can ferment beer wort into a respectable beer. Ten Torulaspora delbrueckii strains were put through the screening system, which included sugar utilization tests, hop resistance tests, ethanol resistance tests, polymerase chain reaction fingerprinting, propagation tests, amino acid catabolism and anabolism, phenolic off-flavour tests and trial fermentations. Trial fermentations were analysed for extract reduction, pH drop, yeast concentration in bulk fluid and fermentation by-products. All investigated strains were able to partly ferment wort sugars and showed high tolerance to hop compounds and ethanol. One of the investigated yeast strains fermented all the wort sugars and produced a respectable fruity flavour and a beer of average ethanol content with a high volatile flavour compound concentration. Two other strains could possibly be used for pre-fermentation as a bio-flavouring agent for beers that have been post-fermented by Saccharomyces strains as a consequence of their low sugar utilization but good flavour-forming properties. Copyright © 2015 John Wiley & Sons, Ltd.

Inheritance of the yeast mitochondrial genome

DEFF Research Database (Denmark)

Piskur, Jure

1994-01-01

Mitochondrion, extrachromosomal genetics, intergenic sequences, genome size, mitochondrial DNA, petite mutation, yeast......Mitochondrion, extrachromosomal genetics, intergenic sequences, genome size, mitochondrial DNA, petite mutation, yeast...

21 CFR 172.590 - Yeast-malt sprout extract.

Science.gov (United States)

2010-04-01

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

Yeasts in sustainable bioethanol production: A review.

Science.gov (United States)

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

2017-07-01

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

Yeasts in sustainable bioethanol production: A review

Directory of Open Access Journals (Sweden)

Siti Hajar Mohd Azhar

2017-07-01

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

Phenol Is the Initial Product Formed during Growth and Degradation of Bromobenzene by Tropical Marine Yeast, Yarrowia lipolytica NCIM 3589 via an Early Dehalogenation Step.

Science.gov (United States)

Vatsal, Aakanksha A; Zinjarde, Smita S; RaviKumar, Ameeta

2017-01-01

Bromobenzene (BrB), a hydrophobic, recalcitrant organic compound, is listed by the environmental protection agencies as an environmental and marine pollutant having hepatotoxic, mutagenic, teratogenic, and carcinogenic effects. The tropical marine yeast Yarrowia lipolytica 3589 was seen to grow aerobically on BrB and displayed a maximum growth rate (μ max ) of 0.04 h -1 . Furthermore, we also observed an increase in cell size and sedimentation velocity for the cells grown on BrB as compared to the glucose grown cells. The cells attached to the hydrophobic bromobenzene droplets through its hydrophobic and acid-base interactions. The BrB (0.5%, 47.6 mM) was utilized by the cells with the release of a corresponding amount of bromide (12.87 mM) and yielded a cell mass of 1.86 g/L after showing 34% degradation in 96 h. Maximum dehalogenase activity of 16.16 U/mL was seen in the cell free supernatant after 24 h of growth. Identification of metabolites formed as a result of BrB degradation, namely, phenol, catechol, cis, cis muconic acid, and carbon dioxide were determined by LC-MS and GC-MS. The initial attack on bromobenzene by Y. lipolytica cells lead to the transient accumulation of phenol as an early intermediate which is being reported for the first time. Degradation of phenol led to catechol which was degraded by the ortho- cleavage pathway forming cis, cis muconic acid and then to Krebs cycle intermediates eventually leading to CO 2 production. The study shows that dehalogenation via an extracellular dehalogenase occurs prior to ring cleavage with phenol as the preliminary degradative compound being produced. The yeast was also able to grow on the degradative products, i.e., phenol and catechol, to varying degrees which would be of potential relevance in the degradation and remediation of xenobiotic environmental bromoaromatic pollutants such as bromobenzene.

Functional characterization of an alpha-factor-like Sordaria macrospora peptide pheromone and analysis of its interaction with its cognate receptor in Saccharomyces cerevisiae.

Science.gov (United States)

Mayrhofer, Severine; Pöggeler, Stefanie

2005-04-01

The homothallic filamentous ascomycete Sordaria macrospora possesses genes which are thought to encode two pheromone precursors and two seven-transmembrane pheromone receptors. The pheromone precursor genes are termed ppg1 and ppg2. The putative products derived from the gene sequence show structural similarity to the alpha-factor precursors and a-factor precursors of the yeast Saccharomyces cerevisiae. Likewise, sequence similarity has been found between the putative products of the pheromone receptor genes pre2 and pre1 and the S. cerevisiae Ste2p alpha-factor receptor and Ste3p a-factor receptor, respectively. To investigate whether the alpha-factor-like pheromone-receptor pair of S. macrospora is functional, a heterologous yeast assay was used. Our results show that the S. macrospora alpha-factor-like pheromone precursor PPG1 is processed into an active pheromone by yeast MATalpha cells. The S. macrospora PRE2 protein was demonstrated to be a peptide pheromone receptor. In yeast MATa cells lacking the endogenous Ste2p receptor, the S. macrospora PRE2 receptor facilitated all aspects of the pheromone response. Using a synthetic peptide, we can now predict the sequence of one active form of the S. macrospora peptide pheromone. We proved that S. macrospora wild-type strains secrete an active pheromone into the culture medium and that disruption of the ppg1 gene in S. macrospora prevents pheromone production. However, loss of the ppg1 gene does not affect vegetative growth or fertility. Finally, we established the yeast assay as an easy and useful system for analyzing pheromone production in developmental mutants of S. macrospora.

Comet assay on tetraploid yeast cells

DEFF Research Database (Denmark)

Rank, Jette; Syberg, Kristian; Jensen, Klara

2009-01-01

Tetraploid yeast cells (Saccharomyces cerevisiae) were used in the comet assay with the intention of developing a new, fast and easy assay for detecting environmental genotoxic agents without using higher organisms. Two DNA-damaging chemicals, H2O2 and acrylamide, together with wastewater from...... three municipal treatment plants were tested for their effect on the yeast-cell DNA. The main problem with using yeast in the comet assay is the necessity to degrade the cell wall. This was achieved by using Zymolase 100 T twice during the procedure, since Zymolase 20 T did not open the cell wall....... Analytical problems that arose due to the small amount of DNA in the yeast nuclei in haploid and diploid cells, which contain 13 Mbp and 26 Mbp DNA per cell, respectively, were solved by using tetraploid yeast cells (52 Mbp) instead. DNA damage was shown after exposure to H2O2 and acrylamide. The lowest dose...

High-density lipoprotein-like particle formation of Synuclein variants.

Science.gov (United States)

Eichmann, Cédric; Kumari, Pratibha; Riek, Roland

2017-01-01

α-Synuclein (α-Syn) is an intrinsically disordered protein in solution whose fibrillar aggregates are the hallmark of Parkinson's disease (PD). Although the specific function of α-Syn is still unclear, its high structural plasticity is key for the interactions of α-Syn with biological membranes. Recently, it has been observed that α-Syn is able to form high-density lipoprotein-like (HDL-like) particles that are reminiscent of self-assembling phospholipid bilayer nanodiscs. Here, we extended our preparation method for the production of α-Syn lipoprotein particles to the β- and γ-Syn variants, and the PD-related familial α-Syn mutants. We show that all human Syns can form stable and homogeneous populations of HDL-like particles with distinct morphologies. Our results characterize the impact of the individual Syns on the formation capacity of these particles and indicate that Syn HDL-like particles are neither causing toxicity nor a toxicity-related loss of α-Syn in PD. © 2016 Federation of European Biochemical Societies.