Production of freeze-dried yeast culture for the brewing of traditional sorghum beer, tchapalo.

PubMed

N'Guessan, Florent K; Coulibaly, Hermann W; Alloue-Boraud, Mireille W A; Cot, Marlène; Djè, Koffi Marcellin

2016-01-01

Freeze-drying is a well-known dehydration method widely used to preserve microorganisms. In order to produce freeze-dried yeast starter culture for the brewing purpose of African sorghum beer, we tested protective agents (sucrose, glucose, glycerol) in combination with support materials (millet, maize, sorghum, and cassava flours) at 1:1 ratio (v/v). The yeast strains Saccharomyces cerevisiae F 12-7 and Candida tropicalis C 0-7 previously isolated from sorghum beer were used in a mixed culture at a ratio of 2:1 (C. tropicalis/S. cerevisiae). After the freeze-drying, the residual water contents were between 0.78 -2.27%, 0.55 -4.09%, and 0.40-2.61%, respectively, with sucrose, glucose and glycerol. The dried yeasts viabilities were between 4.0% and 10.6%. Among the protective agents used, sucrose was found to be the best protectant giving cell viabilities of 8.4-10.6%. Considering the support materials, millet flour was the best support after drying. When the freeze-dried yeast powders were stored at 4°C and room temperature (25-28°C) for up to 3 months, the survival rates were the highest with cassava flour as the support material.

Electron beam radiation of dried fruits and nuts to reduce yeast and mold bioburden.

PubMed

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

2007-04-01

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

21 CFR 573.750 - Pichia pastoris dried yeast.

Code of Federal Regulations, 2010 CFR

2010-04-01

... the following percent-by-weight specifications: (1) Crude protein, not less than 60 percent. (2) Crude fat, not less than 2 percent. (3) Crude fiber, not more than 2 percent. (4) Ash, not more than 13... pastoris dried yeast may be used in feed formulations of broiler chickens as a source of protein not to...

21 CFR 573.750 - Pichia pastoris dried yeast.

Code of Federal Regulations, 2011 CFR

2011-04-01

... the following percent-by-weight specifications: (1) Crude protein, not less than 60 percent. (2) Crude fat, not less than 2 percent. (3) Crude fiber, not more than 2 percent. (4) Ash, not more than 13... pastoris dried yeast may be used in feed formulations of broiler chickens as a source of protein not to...

21 CFR 573.750 - Pichia pastoris dried yeast.

Code of Federal Regulations, 2012 CFR

2012-04-01

... the following percent-by-weight specifications: (1) Crude protein, not less than 60 percent. (2) Crude fat, not less than 2 percent. (3) Crude fiber, not more than 2 percent. (4) Ash, not more than 13... pastoris dried yeast may be used in feed formulations of broiler chickens as a source of protein not to...

21 CFR 573.750 - Pichia pastoris dried yeast.

Code of Federal Regulations, 2014 CFR

2014-04-01

... the following percent-by-weight specifications: (1) Crude protein, not less than 60 percent. (2) Crude fat, not less than 2 percent. (3) Crude fiber, not more than 2 percent. (4) Ash, not more than 13... pastoris dried yeast may be used in feed formulations of broiler chickens as a source of protein not to...

21 CFR 573.750 - Pichia pastoris dried yeast.

Code of Federal Regulations, 2013 CFR

2013-04-01

... the following percent-by-weight specifications: (1) Crude protein, not less than 60 percent. (2) Crude fat, not less than 2 percent. (3) Crude fiber, not more than 2 percent. (4) Ash, not more than 13... pastoris dried yeast may be used in feed formulations of broiler chickens as a source of protein not to...

Post-fermentative production of glutathione by baker's yeast (S. cerevisiae) in compressed and dried forms.

PubMed

Musatti, Alida; Manzoni, Matilde; Rollini, Manuela

2013-01-25

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

Characterization of technological features of dry yeast (strain I-7-43) preparation, product of electrofusion between Saccharomyces cerevisiae and Saccharomyces diastaticus, in industrial application.

PubMed

Kotarska, Katarzyna; Kłosowski, Grzegorz; Czupryński, Bogusław

2011-06-10

The aim of the study was to verify the technological usability and stability of biotechnological features of active dry distillery yeast preparation (strain I-7-43 with amylolytic abilities) applied to full-scale production of agricultural distillery. Various reduced doses of glucoamylase preparation (San-Extra L) were used for starch saccharification, from 90% to 70% in relation to the full standard dose of preparation. The dry distillery yeast I-7-43 were assessed positively in respect to fermentation activity and yield of ethanol production. Application of the dry yeast I-7-43 preparation in distillery practice lowers the costs of spirit production by saving the glucoamylase preparation (up to 30%) used in the process of mash saccharification. Concentrations of the volatile fermentation by-products in raw spirits obtained from fermentations with application of I-7-43 strain were on the levels guaranteeing good organoleptic properties of distillates. Copyright © 2011 Elsevier Inc. All rights reserved.

Brewers dried yeast as a source of mannan oligosaccharides for weanling pigs.

PubMed

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

2002-10-01

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

Effects of the usage of dried brewing yeast in the diets on the performance, egg traits and blood parameters in quails.

PubMed

Yalçın, S; Erol, H; Ozsoy, B; Onbaşılar, I; Yalçın, S

2008-12-01

This experiment was carried out to determine the effects of the usage of dried brewing yeast in quail diets on laying performance, egg traits and blood parameters. A total of 240 Japanese quails (Coturnix coturnix japonica) aged 10 weeks were randomly allocated into one control group and three treatment groups. Each group was divided into five replicates as subgroups, comprising 12 quails each. Dried brewing yeast (Saccharomyces cerevisiae) was used at the levels of 1.5%, 3.0% and 4.5% in the diets of the first, second and third treatment groups, respectively. Soyabean meal was replaced with dried brewing yeast. The diets were formulated to be isocaloric and isonitrogenous. The experimental period lasted 18 weeks. Dietary treatments did not significantly affect body weight, daily feed intake, daily protein intake, egg production, egg weight, feed efficiency, mortality, egg shell thickness, egg albumen index, egg yolk index, egg Haugh unit, the percentages of egg shell, albumen and yolk, excreta moisture and small intestinal pH. Inclusion of 3% and 4.5% dried brewing yeast in diets reduced egg yolk cholesterol concentration as mg per yolk and mg per g yolk (P < 0.01). Blood serum cholesterol of groups fed diets with dried brewing yeast was significantly lower (P < 0.01) than that of the control group. Feeding diets containing 3.0% and 4.5% dried brewing yeast resulted in significant increases (P < 0.01) in blood serum levels of total protein, alanine aminotransferase at the end of the experiment. Blood serum levels of uric acid, triglyceride, aspartate aminotransferase and alkaline phosphatase were not affected by dietary dried brewing yeast. It is concluded that dried brewing yeast can be used up to 4.5% in the diets of laying quails without adverse effects on the measured parameters.

Changes in the relative population size of selected ruminal bacteria following an induced episode of acidosis in beef heifers receiving viable and non-viable active dried yeast.

PubMed

Mohammed, R; Vyas, D; Yang, W Z; Beauchemin, K A

2017-06-01

To characterize the changes in the relative population size (RPS) of select ruminal bacteria and rumen fermentation variables in beef heifers supplemented with a strain of Saccharomyces cerevisiae as viable active dried (ADY) or killed dried (KDY) yeast following an induced episode of ruminal acidosis. Six ruminally cannulated beef heifers fed a diet consisting of 50% forage and 50% grain (dry matter basis) were used in a replicated 3 × 3 Latin square design with three 28-day periods. Treatments were: (i) control (CTRL; no yeast); (ii) ADY (4 g day -1 providing 10 10  CFU per g; AB Vista, UK); and (iii) KDY (4 g day -1 autoclaved ADY). The acidosis challenge was induced on day 22 and rumen samples were collected on day 15 (baseline; BASE), day 22 (challenge day; CHAL), and on day 29 (168th hour post acid challenge or recovery, REC) of each period. Over the study, duration of pH <5·8 (indicative of subacute ruminal acidosis) was less for ADY and KDY than CTRL, with ADY less than KDY. No treatment effects were observed on relative abundance of ruminal bacteria, but the day effect was significant. The RPS of lactate producers and utilizers was greater while RPS of fibrolytic bacteria was lower during CHAL than BASE and REC. Yeast supplementation, irrespective of its viability, showed beneficial effects on ruminal pH variables in animals more susceptible to acidosis. Rumen microbial population was altered with the induction of severe acidosis. Most of the changes reverted back to baseline values during the recovery phase. Yeast supplementation reduced subacute rumen acidosis in the most susceptible cattle, but failed to attenuate severe acidosis induced by a grain challenge. The study provided valuable insight into the mechanism by which acidosis affects cattle performance. Individual animal variation in ruminal fermentation partly explained the variability in response to yeast supplementation in the study. © 2017 Her Majesty the Queen in Right of Canada

Construction of the yeast whole-cell Rhizopus oryzae lipase biocatalyst with high activity.

PubMed

Chen, Mei-ling; Guo, Qin; Wang, Rui-zhi; Xu, Juan; Zhou, Chen-wei; Ruan, Hui; He, Guo-qing

2011-07-01

Surface display is effectively utilized to construct a whole-cell biocatalyst. Codon optimization has been proven to be effective in maximizing production of heterologous proteins in yeast. Here, the cDNA sequence of Rhizopus oryzae lipase (ROL) was optimized and synthesized according to the codon bias of Saccharomyces cerevisiae, and based on the Saccharomyces cerevisiae cell surface display system with α-agglutinin as an anchor, recombinant yeast displaying fully codon-optimized ROL with high activity was successfully constructed. Compared with the wild-type ROL-displaying yeast, the activity of the codon-optimized ROL yeast whole-cell biocatalyst (25 U/g dried cells) was 12.8-fold higher in a hydrolysis reaction using p-nitrophenyl palmitate (pNPP) as the substrate. To our knowledge, this was the first attempt to combine the techniques of yeast surface display and codon optimization for whole-cell biocatalyst construction. Consequently, the yeast whole-cell ROL biocatalyst was constructed with high activity. The optimum pH and temperature for the yeast whole-cell ROL biocatalyst were pH 7.0 and 40 °C. Furthermore, this whole-cell biocatalyst was applied to the hydrolysis of tributyrin and the resulted conversion of butyric acid reached 96.91% after 144 h.

Yeast diversity and dynamics in the production processes of Norwegian dry-cured meat products.

PubMed

Asefa, Dereje T; Møretrø, Trond; Gjerde, Ragnhild O; Langsrud, Solveig; Kure, Cathrine F; Sidhu, Maan S; Nesbakken, Truls; Skaar, Ida

2009-07-31

This study investigate the diversity and dynamics of yeasts in the production processes of one unsmoked and two smoked dry-cured meat products of a Norwegian dry-cured meat production facility. A longitudinal observational study was performed to collect 642 samples from the meat, production materials, room installations and indoor and outdoor air of the production facility. Nutrient rich agar media were used to isolate the yeasts. Morphologically different isolates were re-cultivated in their pure culture forms. Both classical and molecular methods were employed for species identification. Totally, 401 yeast isolates belonging to 10 species of the following six genera were identified: Debaryomyces, Candida, Rhodotorula, Rhodosporidium, Cryptococcus and Sporidiobolus. Debaryomyces hansenii and Candida zeylanoides were dominant and contributed by 63.0% and 26.4% respectively to the total isolates recovered from both smoked and unsmoked products. The yeast diversity was higher at the pre-salting production processes with C. zeylanoides being the dominant. Later at the post-salting stages, D. hansenii occurred frequently. Laboratory studies showed that D. hansenii was more tolerant to sodium chloride and nitrite than C. zeylanoides. Smoking seems to have a killing or a temporary growth inhibiting effect on yeasts that extend to the start of the drying process. Yeasts were isolated only from 31.1% of the environmental samples. They belonged to six different species of which five of them were isolated from the meat samples too. Debaryomyces hansenii and Rhodotorula glutinis were dominant with a 62.6% and 22.0% contribution respectively. As none of the air samples contained D. hansenii, the production materials and room installations used in the production processes were believed to be the sources of contamination. The dominance of D. hansenii late in the production process replacing C. zeylanoides should be considered as a positive change both for the quality and safety

Expression of GPD1 and SIP18 genes during rehydration in active dry industrial Saccharomyces cerevisiae cider-making yeast strains (ADY).

PubMed

Goncerzewicz, Anna; Kamińska-Wojteczek, Karolina; Młynarczyk, Izabella; Misiewicz, Anna

2017-01-01

In this study we determined the influence of different sugar concentration in media, time of rehydration and type of strain on relative expression level of GPD1 and SIP18 genes of active dry cider-making yeast strains, followed by the assessment of the impact of rehydration on the fermentation process. High expression of SIP18 at the beginning of rehydration was shown to be due to high transcription of the gene during the drying process. High sugar concentrations of media initiated transcription of the GPD1 gene and triggered the cellular glycerol biosynthesis pathway in examined strains. Rehydration time and type of strain showed to have no statistically significant impact on the course of the fermentation; RT qPCR results depended mainly on the time of rehydration and sugar concentration of the medium. This is the first attempt to confront rehydration time and molecular mechanisms acting upon rehydration with the course of the fermentation process.

Brewer's Yeast, Saccharomyces cerevisiae, Enhances Attraction of Two Invasive Yellowjackets (Hymenoptera: Vespidae) to Dried Fruit and Fruit Powder.

PubMed

Babcock, Tamara; Gries, Regine; Borden, John; Palmero, Luis; Mattiacci, Analía; Masciocchi, Maité; Corley, Juan; Gries, Gerhard

2017-09-01

The German yellowjacket, Vespula germanica F., and common yellowjacket, Vespula vulgaris L. (Hymenoptera: Vespidae), are pests of significant economic, environmental, and medical importance in many countries. There is a need for the development and improvement of attractive baits that can be deployed in traps to capture and kill these wasps in areas where they are a problem. Yellowjackets are known to feed on fermenting fruit, but this resource is seldom considered as a bait due to its ephemeral nature and its potential attractiveness to nontarget species. We analyzed the headspace volatiles of dried fruit and fruit powder baits with and without Brewer's yeast, Saccharomyces cerevisiae, using gas chromatography-mass spectrometry, and we field tested these baits for their attractiveness to yellowjackets in Argentina. The addition of yeast to dried fruit and fruit powder changed the volatile compositions, increasing the number of alcohols and acids and decreasing the number of aldehydes. Dried fruit and fruit powder baits on their own were hardly attractive to yellowjackets, but the addition of yeast improved their attractiveness by 9- to 50-fold and surpassed the attractiveness of a commercial heptyl butyrate-based wasp lure. We suggest that further research be done to test additional varieties and species of yeasts. A dried fruit or fruit powder bait in combination with yeast could become a useful tool in the management of yellowjackets. © The Author 2017. Published by Oxford University Press on behalf of Entomological Society of America.

Brewer’s Yeast, Saccharomyces cerevisiae, Enhances Attraction of Two Invasive Yellowjackets (Hymenoptera: Vespidae) to Dried Fruit and Fruit Powder

PubMed Central

Gries, Regine; Borden, John; Palmero, Luis; Mattiacci, Analía; Masciocchi, Maité; Corley, Juan; Gries, Gerhard

2017-01-01

Abstract The German yellowjacket, Vespula germanica F., and common yellowjacket, Vespula vulgaris L. (Hymenoptera: Vespidae), are pests of significant economic, environmental, and medical importance in many countries. There is a need for the development and improvement of attractive baits that can be deployed in traps to capture and kill these wasps in areas where they are a problem. Yellowjackets are known to feed on fermenting fruit, but this resource is seldom considered as a bait due to its ephemeral nature and its potential attractiveness to nontarget species. We analyzed the headspace volatiles of dried fruit and fruit powder baits with and without Brewer’s yeast, Saccharomyces cerevisiae, using gas chromatography–mass spectrometry, and we field tested these baits for their attractiveness to yellowjackets in Argentina. The addition of yeast to dried fruit and fruit powder changed the volatile compositions, increasing the number of alcohols and acids and decreasing the number of aldehydes. Dried fruit and fruit powder baits on their own were hardly attractive to yellowjackets, but the addition of yeast improved their attractiveness by 9- to 50-fold and surpassed the attractiveness of a commercial heptyl butyrate-based wasp lure. We suggest that further research be done to test additional varieties and species of yeasts. A dried fruit or fruit powder bait in combination with yeast could become a useful tool in the management of yellowjackets. PMID:28922898

Microbial ecology of extreme environments: Antarctic dry valley yeasts and growth in substrate limited habitats

NASA Technical Reports Server (NTRS)

Vishniac, H. S.

1981-01-01

The multiple stresses temperature, moisture, and for chemoheterotrophs, sources of carbon and energy of the Dry Valley Antarctica soils allow at best depauperate communities, low in species diversity and population density. The nature of community structure, the operation of biogeochemical cycles, the evolution and mechanisms of adaptation to this habitat are of interest in informing speculations upon life on other planets as well as in modeling the limits of gene life. Yeasts of the Cryptococcus vishniacil complex (Basidiobiastomycetes) are investigated, as the only known indigenes of the most hostile, lichen free, parts of the Dry Valleys. Methods were developed for isolating these yeasts (methods which do not exclude the recovery of other microbiota). The definition of the complex was refined and the importance of nitrogen sources was established as well as substrate competition in fitness to the Dry Valley habitats.

Application of anhydrobiosis and dehydration of yeasts for non-conventional biotechnological goals.

PubMed

Rapoport, Alexander; Turchetti, Benedetta; Buzzini, Pietro

2016-06-01

Dehydration of yeast cells causes them to enter a state of anhydrobiosis in which their metabolism is temporarily and reversibly suspended. This unique state among organisms is currently used in the production of active dry yeasts, mainly used in baking and winemaking. In recent decades non-conventional applications of yeast dehydration have been proposed for various modern biotechnologies. This mini-review briefly summarises current information on the application of dry yeasts in traditional and innovative fields. It has been shown that dry yeast preparations can be used for the efficient protection, purification and bioremediation of the environment from heavy metals. The high sorption activity of dehydrated yeasts can be used as an interesting tool in winemaking due to their effects on quality and taste. Dry yeasts are also used in agricultural animal feed. Another interesting application of yeast dehydration is as an additional stage in new methods for the stable immobilisation of microorganisms, especially in cases when biotechnologically important strains have no affinity with the carrier. Such immobilisation methods also provide a new approach for the successful conservation of yeast strains that are very sensitive to dehydration. In addition, the application of dehydration procedures opens up new possibilities for the use of yeast as a model system. Separate sections of this review also discuss possible uses of dry yeasts in biocontrol, bioprotection and biotransformations, in analytical methods as well as in some other areas.

Performance of Clarias gariepinus Fed Dried Brewer's Yeast (Saccharomyces cerevisiae) Slurry in Replacement for Soybean Meal.

PubMed

Solomon, Shola Gabriel; Ataguba, Gabriel Arome; Itodo, Gabriel Enemona

2017-01-01

Following disparity of earlier results, this study tested the performance of African catfish Clarias gariepinus fed dried brewer's yeast slurry meal (DBYM) based diets. Fingerlings of C. gariepinus with pooled mean initial weight of 1.58 ± 0.01 g were stocked in hapas (1 m × 1 m × 1 m) immersed in an earthen pond at a density of 15 fish per cage. Five diets with increasing substitution of soybean meal with 25%, 50%, 75%, and 100% of dried brewer's yeast and a control without dried brewer's yeast (0% substitution) were evaluated for 8 weeks. Palatability of diets reduced with increasing levels of DBYM. Growth and utilization parameters such as weight gain, feed conversion ratio, protein efficiency ratio, and specific growth rate differed significantly ( p < 0.05) among treated groups. Specific growth rate decreased with increasing substitution while the best feed conversion ratio was obtained in the diet devoid of DBYM. Protein efficiency and utilization decreased with increasing levels of DBYM. Body composition was also affected by inclusion of DBYM with significant differences ( p < 0.05) being observed across the diets. The trend in body composition follows the utilization of the diets. We conclude that the optimal range of inclusion and substitution of soybean meal with DBYM in C. gariepinus feed is between 1% and 14% of dry matter.

Performance of Clarias gariepinus Fed Dried Brewer's Yeast (Saccharomyces cerevisiae) Slurry in Replacement for Soybean Meal

PubMed Central

Solomon, Shola Gabriel; Itodo, Gabriel Enemona

2017-01-01

Following disparity of earlier results, this study tested the performance of African catfish Clarias gariepinus fed dried brewer's yeast slurry meal (DBYM) based diets. Fingerlings of C. gariepinus with pooled mean initial weight of 1.58 ± 0.01 g were stocked in hapas (1 m × 1 m × 1 m) immersed in an earthen pond at a density of 15 fish per cage. Five diets with increasing substitution of soybean meal with 25%, 50%, 75%, and 100% of dried brewer's yeast and a control without dried brewer's yeast (0% substitution) were evaluated for 8 weeks. Palatability of diets reduced with increasing levels of DBYM. Growth and utilization parameters such as weight gain, feed conversion ratio, protein efficiency ratio, and specific growth rate differed significantly (p < 0.05) among treated groups. Specific growth rate decreased with increasing substitution while the best feed conversion ratio was obtained in the diet devoid of DBYM. Protein efficiency and utilization decreased with increasing levels of DBYM. Body composition was also affected by inclusion of DBYM with significant differences (p < 0.05) being observed across the diets. The trend in body composition follows the utilization of the diets. We conclude that the optimal range of inclusion and substitution of soybean meal with DBYM in C. gariepinus feed is between 1% and 14% of dry matter. PMID:28239492

Efficiency of mitochondrial DNA restriction analysis and RAPD-PCR to characterize yeasts growing on dry-cured Iberian ham at the different geographic areas of ripening.

PubMed

Andrade, María J; Rodríguez, Mar; Casado, Eva; Córdoba, Juan J

2010-03-01

The efficiency of mitochondrial DNA (mtDNA) restriction analysis and random amplification of polymorphic DNA (RAPD)-PCR to characterize yeasts growing on dry-cured Iberian ham was evaluated. Besides, the distribution of the main species and biotypes of yeasts in the different ripening areas of this product was investigated. MtDNA restriction analysis allowed yeast characterization at species and strain level. RAPD-PCR with the primers (GACA)(4) and (GAC)(5) was inappropriate for characterization at species level. Most of the mtDNA restriction patterns detected in dry-cured Iberian ham were consistent with Debaryomyces hansenii. Several yeasts biotypes were associated to specific geographic areas of dry-cured Iberian ham ripening. Copyright 2009 Elsevier Ltd. All rights reserved.

Inventions on baker's yeast strains and specialty ingredients.

PubMed

Gélinas, Pierre

2009-06-01

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

Noninvasive characterization of the fission yeast cell cycle by monitoring dry mass with digital holographic microscopy.

PubMed

Rappaz, Benjamin; Cano, Elena; Colomb, Tristan; Kühn, Jonas; Depeursinge, Christian; Simanis, Viesturs; Magistretti, Pierre J; Marquet, Pierre

2009-01-01

Digital holography microscopy (DHM) is an optical technique which provides phase images yielding quantitative information about cell structure and cellular dynamics. Furthermore, the quantitative phase images allow the derivation of other parameters, including dry mass production, density, and spatial distribution. We have applied DHM to study the dry mass production rate and the dry mass surface density in wild-type and mutant fission yeast cells. Our study demonstrates the applicability of DHM as a tool for label-free quantitative analysis of the cell cycle and opens the possibility for its use in high-throughput screening.

Dry-grind processing using amylase corn and superior yeast to reduce the exogenous enzyme requirements in bioethanol production.

PubMed

Kumar, Deepak; Singh, Vijay

2016-01-01

Conventional corn dry-grind ethanol production process requires exogenous alpha and glucoamylases enzymes to breakdown starch into glucose, which is fermented to ethanol by yeast. This study evaluates the potential use of new genetically engineered corn and yeast, which can eliminate or minimize the use of these external enzymes, improve the economics and process efficiencies, and simplify the process. An approach of in situ ethanol removal during fermentation was also investigated for its potential to improve the efficiency of high-solid fermentation, which can significantly reduce the downstream ethanol and co-product recovery cost. The fermentation of amylase corn (producing endogenous α-amylase) using conventional yeast and no addition of exogenous α-amylase resulted in ethanol concentration of 4.1 % higher compared to control treatment (conventional corn using exogenous α-amylase). Conventional corn processed with exogenous α-amylase and superior yeast (producing glucoamylase or GA) with no exogenous glucoamylase addition resulted in ethanol concentration similar to control treatment (conventional yeast with exogenous glucoamylase addition). Combination of amylase corn and superior yeast required only 25 % of recommended glucoamylase dose to complete fermentation and achieve ethanol concentration and yield similar to control treatment (conventional corn with exogenous α-amylase, conventional yeast with exogenous glucoamylase). Use of superior yeast with 50 % GA addition resulted in similar increases in yield for conventional or amylase corn of approximately 7 % compared to that of control treatment. Combination of amylase corn, superior yeast, and in situ ethanol removal resulted in a process that allowed complete fermentation of 40 % slurry solids with only 50 % of exogenous GA enzyme requirements and 64.6 % higher ethanol yield compared to that of conventional process. Use of amylase corn and superior yeast in the dry-grind processing industry

The effect of yeast (Saccharomyces cerevisiae) on nutrient intake, digestibility and finishing performance of lambs fed a diet based on dried molasses sugar beet-pulp.

PubMed

Payandeh, S; Kafilzadeh, F

2007-12-15

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

Study of the counts, species and characteristics of the yeast population during the manufacture of dry-cured "lacón". Effect of salt level.

PubMed

Purriños, Laura; García Fontán, María C; Carballo, Javier; Lorenzo, José M

2013-05-01

The aim of this work was to study the yeast population during the manufacture of dry-cured "lacón" (a Spanish traditional meat product) and the effect of the salting time. For this study, six batches of "lacón" were manufactured with three different salting times (LS (3 days of salting), MS (4 days of salting) and HS (5 days of salting)). Yeast counts increased significantly (P < 0.001) during the whole process from 2.60 to 6.37 log cfu/g. An increased length of salting time did not affect yeast counts throughout the manufacture of dry-cured "lacón", although the highest yeast counts were obtained from LS batches. A total of 226 isolates were obtained from dry-cured "lacón" during drying-ripening stage, of which 151 were yeasts and were identified at the species level using molecular techniques. The total of 151 identified yeasts belonged to 4 different genera: Debaryomyces, Candida, Cryptococcus and Rhodotorula. Debaryomyces hansenii was the most abundant species isolated throughout the whole process as much in the interior as in the exterior of the pieces of three salt levels of "lacón" studied, while Candida zeylanoides was only isolated from the interior of MS and HS batches and from the exterior of LS and HS groups, but at lesser proportion than D. hansenii. Copyright © 2012. Published by Elsevier Ltd.

Antimicrobial activity of yeasts against some pathogenic bacteria

PubMed Central

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

2017-01-01

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

Microbial ecology of extreme environments: Antarctic dry valley yeasts and growth in substrate-limited habitats

NASA Technical Reports Server (NTRS)

Vishniac, H. S.

1982-01-01

The success of the Antarctic Dry Valley yeasts presumeably results from adaptations to multiple stresses, to low temperatures and substrate-limitation as well as prolonged resting periods enforced by low water availability. Previous investigations have suggested that the crucial stress is substrate limitation. Specific adaptations may be pinpointed by comparing the physiology of the Cryptococcus vishniacii complex, the yeasts of the Tyrol Valley, with their congeners from other habitats. Progress was made in methods of isolation and definition of ecological niches, in the design of experiments in competition for limited substrate, and in establishing the relationships of the Cryptococcus vishniacii complex with other yeasts. In the course of investigating relationships, a new method for 25SrRNA homology was developed. For the first time it appears that 25SrRNA homology may reflect parallel or convergent evolution.

Differentiation of yeasts growing on dry-cured Iberian ham by mitochondrial DNA restriction analysis, RAPD-PCR and their volatile compounds production.

PubMed

Andrade, M J; Rodríguez, M; Casado, E M; Bermúdez, E; Córdoba, J J

2009-09-01

The efficiency of mitochondrial DNA (mtDNA) restriction analysis, RAPD-PCR and volatile compounds analysis to differentiate yeast biotypes involved in flavour development of dry-cured Iberian ham throughout the ripening process is evaluated. For this purpose, 86 yeasts isolated from Iberian hams in the main ripening stages at different industries of the four Protected Designations of Origin of this product, were used. The combination of mtDNA restriction analysis and RAPD-PCR using the primer (GACA)4 showed a higher variability in the yeast species detected than obtained using only mtDNA restriction analysis. Only two species, Debaryomyces hansenii and Candida zeylanoides, were identified throughout the whole ripening process and a wide diversity of biotypes was found in these two species, with those of D. hansenii predominating. Clear differences between biotypes were detected in the generation of volatile compounds, with the biotype C2-2 of D. hansenii showing the highest concentrations of volatiles. The combined use of mtDNA restriction analysis and RAPD-PCR distinguishes yeast biotypes with different production of volatile compounds. In addition, analysis of the production profile of volatile compounds is needed to differentiate yeast strains of the same biotype recovered at different stages of ripening. Thus, the combination of these three methods could be very useful to select or monitor yeasts as starter cultures in dry-cured meat products.

Conditions of activation of yeast plasma membrane ATPase.

PubMed

Sychrová, H; Kotyk, A

1985-04-08

The in vivo activation of the H+-ATPase of baker's yeast plasma membrane found by Serrano in 1983 was demonstrated with D-glucose aerobically and anaerobically (as well as in a respiration-deficient mutant) and, after suitable induction, with maltose, trehalose, and galactose. The activated but not the control ATPase was sensitive to oligomycin. No activation was possible in a cell-free extract with added glucose. The ATPase was not activated in yeast protoplasts which may account for the absence of glucose-stimulated secondary active transports in these wall-less cells and provide support for a microscopic coupling between ATPase activity and these transports in yeast cells.

Comparison of dry sheet media and conventional agar media methods for enumerating yeasts and molds in food.

PubMed

Beuchat, L R; Mann, David A; Gurtler, Joshua B

2007-11-01

A study was done to compare Nissui Compact Dry Yeast and Mold plates (CDYM), 3M Petrifilm Yeast and Mold count plates (PYM), dichloran-rose bengal chloramphenicol (DRBC) agar, and dichloran 18% glycerol (DG18) agar for enumerating yeasts and molds naturally occurring in 97 foods (grains, legumes, raw fruits and vegetables, nuts, dairy products, meats, and miscellaneous processed foods and dry mixes). Correlation coefficients for plates incubated for 5 days were DG18 versus DRBC (0.93), PYM versus DRBC (0.81), CDYM versus DG18 (0.81), PYM versus DG18 (0.80), CDYM versus DRBC (0.79), and CDYM versus PYM (0.75). The number of yeasts and molds recovered from a group of foods (n = 32) analyzed on a weight basis (CFU per gram) was not significantly different (alpha = 0.05) when samples were plated on DRBC, DG18, PYM, or CDYM. However, the order of recovery from foods (n = 65) in a group analyzed on a unit or piece basis, or a composite of both groups (n = 97), was DRBC > DG18 = CDYM > PYM. Compared with PYM, CDYM recovered equivalent, significantly higher (alpha = 0.05) or significantly lower (alpha = 0.05) numbers of yeasts and molds in 51.5, 27.8, and 20.6%, respectively, of the 97 foods tested; respective values were 68.8, 15.6, and 15.6% in the small group (n = 32) and 43.1, 33.8, and 23.1% in the large group (n = 65) of foods. The two groups contained different types of foods, the latter consisting largely (73.8%) of raw fruits (n = 16) and vegetables (n = 32). Differences in efficacy of the four methods in recovering yeasts and molds from foods in the two groups are attributed in part to differences in genera and predominant mycoflora. While DG18 agar, CDYM, and PYM appear to be acceptable for enumerating yeasts and molds in the foods analyzed in this study, overall, DRBC agar recovered higher numbers from the 97 test foods, thereby supporting its recommended use as a general purpose medium for mycological analysis.

Effect of moisture content on the invertase activity of freeze-dried S. cerevisiae.

PubMed

Pitombo, R N; Spring, C; Passos, R F; Tonato, M; Vitolo, M

1994-08-01

The invertase activity of intact Saccharomyces cerevisiae submitted to freezing-thawing was affected by pH, the chemical nature of the buffer, and the freezing cooling rate (CR), leading in some cases to a complete invertase inactivation (acetate buffer, pH 4.0, CR = 0.5 degree C/min). Once established under adequate freezing conditions the invertase activity remained unchanged after freeze-drying. Nevertheless, in some cases the cell-growing capability after freeze-drying diminished around 70%, mainly if the frozen cell suspension was attained through freezing carried out at CR = 0.5 degree C/min. Water sorption isotherms of freeze-dried samples (freeze-dryer Edwards L-4KR; 30 degrees C and 0.1 mB) were determined at 10 and 25 degrees C. The monolayer moisture content (MMC) at each temperature (12.7 and 3.71 for 10 and 25 degrees C, respectively) was calculated from isotherms by applying BET and GAB models. Freeze-dried yeast with water activity (Aw) between 0 and 0.33 (about the MMC value) maintained at 25 degrees C for 235 days and at 89 degrees C for 15 min retained at least 85% of its original invertase activity (IA), whereas samples with Aw > MMC lost at least 60% of its IA. X ray diffraction showed that the freeze-dried cake before and after storage presented an amorphous structure.

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

PubMed

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.

Fission yeast Csk1 is a CAK-activating kinase (CAKAK).

PubMed Central

Hermand, D; Pihlak, A; Westerling, T; Damagnez, V; Vandenhaute, J; Cottarel, G; Mäkelä, T P

1998-01-01

Cell cycle progression is dependent on the sequential activity of cyclin-dependent kinases (CDKs). For full activity, CDKs require an activating phosphorylation of a conserved residue (corresponding to Thr160 in human CDK2) carried out by the CDK-activating kinase (CAK). Two distinct CAK kinases have been described: in budding yeast Saccharomyces cerevisiae, the Cak1/Civ1 kinase is responsible for CAK activity. In several other species including human, Xenopus, Drosophila and fission yeast Schizosaccharomyces pombe, CAK has been identified as a complex homologous to CDK7-cyclin H (Mcs6-Mcs2 in fission yeast). Here we identify the fission yeast Csk1 kinase as an in vivo activating kinase of the Mcs6-Mcs2 CAK defining Csk1 as a CAK-activating kinase (CAKAK). PMID:9857180

Microbiological and fermentative properties of baker's yeast starter used in breadmaking.

PubMed

Reale, A; Di Renzo, T; Succi, M; Tremonte, P; Coppola, R; Sorrentino, E

2013-08-01

This study assessed the levels of microbial contaminants in liquid, compressed and dry commercial baker's yeasts used as starters in breadmaking. Eumycetes, Enterobacteriaceae, total and fecal coliforms, Bacillus spp., and lactic acid bacteria (LAB), in particular enterococci, were quantified. Results obtained in this study highlighted that baker's yeast could represent a potential vehicle of spoilage and undesirable microorganisms into the baking environment, even if these do not influence the leavening activity in the dough, as ascertained by rheofermentometer analysis. Different microbial groups, such as spore-forming bacteria and moulds, were found in baker's yeast starters. Moreover, different species of LAB, which are considered the main contaminants in large-scale yeast fermentations, were isolated and identified by Denaturing Gradient Gel Electrophoresis (DGGE) and 16S rDNA sequencing. The most recurrent species were Lactobacillus plantarum, Enterococcus faecalis, and Enterococcus durans, isolated from both compressed and dry starters, whereas strains belonging to Leuconostoc and Pediococcus genera were found only in dry ones. Nested-Polymerase Chain Reaction (Nested-PCR) and Randomly Amplified Polymorphic DNA-PCR (RAPD-PCR) were also used to highlight the biodiversity of the different commercial yeast strains, and to ascertain the culture purity. © 2013 Institute of Food Technologists®

Diversity and killer activity of yeasts in Malaysian fermented food samples.

PubMed

Lim, S L; Tay, S T

2011-08-01

The biodiversity and the killer activity of yeasts isolated from various types of fermented food in Malaysia were investigated in this study. Of 252 yeasts isolated from 48 fermented food samples in this study, 19 yeast species were identified based on sequence analysis of the ITS1-5.8S-ITS2 partial fragments of the yeasts. A total of 29 (11.5%) of the yeast isolates demonstrated killer activity to at least one Candida species tested in this study; including 22 isolates of Trichosporon asahii, 4 isolates of Pichia anomala, and one isolate each of Pichia norvegensis, Pichia fermentans and Issatchenkia orientalis, respectively. The presence of killer yeasts reflects antagonism that occurs during microbial interaction in the fermented food, whereby certain yeasts produce killer toxins and possibly other toxic substances in competition for limited nutrients and space. The anti-Candida activity demonstrated by killer yeasts in this study should be further explored for development of alternative therapy against candidiasis.

21 CFR 172.898 - Bakers yeast glycan.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Bakers yeast glycan. 172.898 Section 172.898 Food... Bakers yeast glycan. Bakers yeast glycan may be safely used in food in accordance with the following conditions: (a) Bakers yeast glycan is the comminuted, washed, pasteurized, and dried cell walls of the yeast...

The effect of supplementation with three commercial inactive dry yeasts on the colour, phenolic compounds, polysaccharides and astringency of a model wine solution and red wine.

PubMed

González-Royo, Elena; Esteruelas, Mireia; Kontoudakis, Nikolaos; Fort, Francesca; Canals, Joan Miquel; Zamora, Fernando

2017-01-01

Nowadays supplementing red wines with commercial inactive dry yeasts is a widespread practice in winemaking because it leads to better balanced wines through increased mouthfeel and smooth astringency. The aim of this article is to study, in a red wine and in a model wine solution, how supplementation with three commercial inactive dry yeasts affects chemical composition and astringency. This will give us a better understanding of the action mechanism involved. The results suggest that this action mechanism is related to two different phenomena. The first is that inactive yeasts release polysaccharides and oligosaccharides which can increase mouthfeel and inhibit interactions between salivary protein and tannins. The second is that they have a direct effect on the precipitation or absorption of proanthocyanidins, especially the larger polymers, which have been described as the most astringent. It can be concluded that supplementation with inactive yeasts is indeed a useful tool for smoothing the astringency of red wines. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

21 CFR 184.1983 - Bakers yeast extract.

Code of Federal Regulations, 2013 CFR

2013-04-01

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

21 CFR 184.1983 - Bakers yeast extract.

Code of Federal Regulations, 2012 CFR

2012-04-01

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

Effect of freeze-drying on viability and in vitro probiotic properties of a mixture of lactic acid bacteria and yeasts isolated from kefir.

PubMed

Bolla, Patricia A; Serradell, María de los Angeles; de Urraza, Patricio J; De Antoni, Graciela L

2011-02-01

The effect of freeze-drying on viability and probiotic properties of a microbial mixture containing selected bacterial and yeast strains isolated from kefir grains (Lactobacillus kefir, Lactobacillus plantarum, Lactococcus lactis, Saccharomyces cerevisiae and Kluyveromyces marxianus) was studied. The microorganisms were selected according to their potentially probiotic properties in vitro already reported. Two types of formulations were performed, a microbial mixture (MM) suspended in milk and a milk product fermented with MM (FMM). To test the effect of storage on viability of microorganisms, MM and FMM were freeze-dried and maintained at 4°C for six months. After 180 days of storage at 4°C, freeze-dried MM showed better survival rates for each strain than freeze-dried FMM. The addition of sugars (trehalose or sucrose) did not improve the survival rates of any of the microorganisms after freeze-drying. Freeze-drying did not affect the capacity of MM to inhibit growth of Shigella sonnei in vitro, since the co-incubation of this pathogen with freeze-dried MM produced a decrease of 2 log in Shigella viability. The safety of freeze-dried MM was tested in mice and non-translocation of microorganisms to liver or spleen was observed in BALB/c mice feed ad libitum during 7 or 20 days. To our knowledge, this is the first report about the effect of freeze-drying on viability, in vitro probiotic properties and microbial translocation of a mixture containing different strains of both bacteria and yeasts isolated from kefir.

Screening and characterization of amylase and cellulase activities in psychrotolerant yeasts.

PubMed

Carrasco, Mario; Villarreal, Pablo; Barahona, Salvador; Alcaíno, Jennifer; Cifuentes, Víctor; Baeza, Marcelo

2016-02-19

Amylases and cellulases have great potential for application in industries such as food, detergent, laundry, textile, baking and biofuels. A common requirement in these fields is to reduce the temperatures of the processes, leading to a continuous search for microorganisms that secrete cold-active amylases and cellulases. Psychrotolerant yeasts are good candidates because they inhabit cold-environments. In this work, we analyzed the ability of yeasts isolated from the Antarctic region to grow on starch or carboxymethylcellulose, and their potential extracellular amylases and cellulases. All tested yeasts were able to grow with soluble starch or carboxymethylcellulose as the sole carbon source; however, not all of them produced ethanol by fermentation of these carbon sources. For the majority of the yeast species, the extracellular amylase or cellulase activity was higher when cultured in medium supplemented with glucose rather than with soluble starch or carboxymethylcellulose. Additionally, higher amylase activities were observed when tested at pH 5.4 and 6.2, and at 30-37 °C, except for Rhodotorula glacialis that showed elevated activity at 10-22 °C. In general, cellulase activity was high until pH 6.2 and between 22-37 °C, while the sample from Mrakia blollopis showed high activity at 4-22 °C. Peptide mass fingerprinting analysis of a potential amylase from Tetracladium sp. of about 70 kDa, showed several peptides with positive matches with glucoamylases from other fungi. Almost all yeast species showed extracellular amylase or cellulase activity, and an inducing effect by the respective substrate was observed in a minor number of yeasts. These enzymatic activities were higher at 30 °C in most yeast, with highest amylase and cellulase activity in Tetracladium sp. and M. gelida, respectively. However, Rh. glacialis and M. blollopis displayed high amylase or cellulase activity, respectively, under 22 °C. In this sense, these yeasts are interesting

Enhanced leavening properties of baker's yeast by reducing sucrase activity in sweet dough.

PubMed

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

2016-07-01

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

Effects of yeast, fermentation time, and preservation methods on tarhana.

PubMed

Gurbuz, Ozan; Gocmen, Duygu; Ozmen, Nese; Dagdelen, Fatih

2010-01-01

The physicochemical properties of tarhana soup produced with different dough treatments, fermentation times, and preservation methods were examined. Tarhana doughs were prepared with yogurt (control) or baker's yeast (Saccharomyces cerevisiae) and fermented for 3 days. Samples were taken at 24, 48, and 72 hr. Samples were then preserved via one of four methods: sun dried, dried in the shade, vacumn dried, and frozen. Frozen samples produced lower organic acid levels after 72 hr of fermentation in both control (0.68 g/100 g) and yeast (0.61 g/100 g) applications than samples that were dried (0.94 g/100 g control samples; 0.81 g/100 g samples with yeast). Increasing fermentation time resulted in a significant effect on the formation of organic acid in the tarhana (p < .01). At 72 hr of fermentation, total acidity increased 11%, 17%, and 23% for tarhana samples vacumn-dried, sun-dried, and dried in the shade, respectively. Preservation methods also affected the moisture, ash, crude protein, total acidity, pH, salt, fat, reducing sugar levels, and the sensory assestment of tarhana soup (p < .01). Sensory characteristics were not significantly affected by baker's yeast in any of the preservation methods used (p > .01). However, sensory scores for tarhana prepared from the samples dried in a sheltered area showed a reduction in color desireablilty as the fermentation time increased. The soup prepared from frozen tarhana (72 hr fermentation, with yeast) had the highest scores with respect to color, mouth feel, flavor, and overall acceptability. Vacuum-dried samples' scores in these areas were also high in comparison to the two other drying methods.

Evaluation of pectinolytic activities for oenological uses from psychrotrophic yeasts.

PubMed

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

2013-08-01

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

Proteases and caspase-like activity in the yeast Saccharomyces cerevisiae.

PubMed

Wilkinson, Derek; Ramsdale, Mark

2011-10-01

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

Astaxanthinogenesis in the yeast Phaffia rhodozyma - optimization of low-cost culture media and yeast cell-wall lysis

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

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

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

Alcohol production from Jerusalem artichoke using yeasts with inulinase activity

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

Guiraud, J.P.; Daurelles, J.; Galzy, P.

1981-07-01

The purpose of this article is to show that yeasts with inulinase activity can be used to produce ethanol from the Jerusalem artichoke (Helianthus tuberosus L.). The results show that a fermentable extract can be easily obtained from the Jerusalem artichoke even under cold conditions. Yeasts with inulinase activity can be used to produce ethanol with good profitability. 19 refs.

Mitochondria inheritance is a key factor for tolerance to dehydration in wine yeast production.

PubMed

Picazo, C; Gamero-Sandemetrio, E; Orozco, H; Albertin, W; Marullo, P; Matallana, E; Aranda, A

2015-03-01

Mitochondria are the cell's powerhouse when organisms are grown in the presence of oxygen. They are also the source of reactive oxygen species that cause damage to the biochemical components of the cell and lead to cellular ageing and death. Under winemaking conditions, Saccharomyces yeasts exclusively have a fermentative metabolism due to the high sugar content of grape must. However, their production as an active dry yeast (ADY) form required aerobic propagation and a dehydration process. In these industrial steps, oxidative stress is particularly harmful for the cell. In this work, we analysed the impact of the mitochondrial genome on oxidative stress response, longevity and dehydration tolerance using the synthetic interspecific hybrids obtained between two S. cerevisiae and S. uvarum strains. The isogenic nature of nuclear DNA of such hybrids allowed us to analyse the impact of mitochondrial DNA for fermentative and oxidative stress conditions. Under grape must conditions, the inheritance of mitochondrial DNA poorly impacted the fermentative performance of interspecific hybrids, unlike the hybrids with S. cerevisiae mitochondrial inheritance, which displayed increased tolerance to oxidative stress and dehydration, and showed an extended chronological longevity when cells were grown with aeration. In modern oenology, yeast starters are employed to inoculate grape juice, usually in the form of active dry yeast (ADY). The dehydration process implies stressful conditions that lead to oxidative damage. Other yeast species and interspecific hybrids other than Saccharomyces cerevisiae may be used to confer novel properties to the final product. However, these yeasts are usually more sensitive to drying. Understanding the causes of oxidative stress tolerance is therefore necessary for developing the use of these organisms in industry. This study indicates the impact of mitochondrial DNA inheritance for oxidative stress resistance in an interspecific context using

Evaluation of grain distillers dried yeast as a fish meal substitute in practical-type diets of juvenile rainbow trout, Oncorhynchus mykiss

USDA-ARS?s Scientific Manuscript database

Grain distillers dried yeast (GDDY) is a single-cell protein obtained as a co-product during the production of fuel ethanol that may have potential as a protein replacement for rainbow trout. The goal of this study was to examine the suitability of GDDY as a replacement for fishmeal on a digestible ...

Screening of plant extracts for antimicrobial activity against bacteria and yeasts with dermatological relevance.

PubMed

Weckesser, S; Engel, K; Simon-Haarhaus, B; Wittmer, A; Pelz, K; Schempp, C M

2007-08-01

There is cumulative resistance against antibiotics of many bacteria. Therefore, the development of new antiseptics and antimicrobial agents for the treatment of skin infections is of increasing interest. We have screened six plant extracts and isolated compounds for antimicrobial effects on bacteria and yeasts with dermatological relevance. The following plant extracts have been tested: Gentiana lutea, Harpagophytum procumbens, Boswellia serrata (dry extracts), Usnea barbata, Rosmarinus officinalis and Salvia officinalis (supercritical carbon dioxide [CO2] extracts). Additionally, the following characteristic plant substances were tested: usnic acid, carnosol, carnosic acid, ursolic acid, oleanolic acid, harpagoside, boswellic acid and gentiopicroside. The extracts and compounds were tested against 29 aerobic and anaerobic bacteria and yeasts in the agar dilution test. U. barbata-extract and usnic acid were the most active compounds, especially in anaerobic bacteria. Usnea CO2-extract effectively inhibited the growth of several Gram-positive bacteria like Staphylococcus aureus (including methicillin-resistant strains - MRSA), Propionibacterium acnes and Corynebacterium species. Growth of the dimorphic yeast Malassezia furfur was also inhibited by Usnea-extract. Besides the Usnea-extract, Rosmarinus-, Salvia-, Boswellia- and Harpagophytum-extracts proved to be effective against a panel of bacteria. It is concluded that due to their antimicrobial effects some of the plant extracts may be used for the topical treatment of skin disorders like acne vulgaris and seborrhoic eczema.

Improved shelf life of dried Beauveria bassiana blastospores using convective drying and active packaging processes.

PubMed

Mascarin, Gabriel Moura; Jackson, Mark A; Behle, Robert W; Kobori, Nilce N; Júnior, Ítalo Delalibera

2016-10-01

The yeast form (blastospore) of the dimorphic insect-pathogenic fungus Beauveria bassiana can be rapidly produced using liquid fermentation methods but is generally unable to survive rapid dehydration processes or storage under non-refrigerated conditions. In this study, we evaluated the influence of two convective drying methods, various modified atmosphere packaging systems, and storage temperatures on the desiccation tolerance, storage stability, and virulence of blastospores of B. bassiana ESALQ 1432. All blastospore formulations were dried to <5 % water content equivalent to aw < 0.3. The viability of B. bassiana blastospores after air drying and spray drying was greater than 80 %. Vacuum-packaged blastospores remained viable longer when stored at 4 °C compared with 28 °C with virtually no loss in viability over 9 months regardless the drying method. When both oxygen and moisture scavengers were added to sealed packages of dried blastospore formulations stored at 28 °C, viability was significantly prolonged for both air- and spray-dried blastospores. The addition of ascorbic acid during spray drying did not improve desiccation tolerance but enhanced cell stability (∼twofold higher half-life) when stored at 28 °C. After storage for 4 months at 28 °C, air-dried blastospores produced a lower LC80 and resulted in higher mortality to whitefly nymphs (Bemisia tabaci) when compared with spray-dried blastospores. These studies identified key storage conditions (low aw and oxygen availability) that improved blastospore storage stability at 28 °C and will facilitate the commercial development of blastospores-based bioinsecticides.

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

PubMed

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

2014-08-20

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

[Detection of viable metabolically active yeast cells using a colorimetric assay].

PubMed

Růzicka, F; Holá, V

2008-02-01

The increasing concern of yeasts able to form biofilm brings about the need for susceptibility testing of both planktonic and biofilm cells. Detection of viability or metabolic activity of yeast cells after exposure to antimicrobials plays a key role in the assessment of susceptibility testing results. Colorimetric assays based on the color change of the medium in the presence of metabolically active cells proved suitable for this purpose. In this study, the usability of a colorimetric assay with the resazurin redox indicator for monitoring the effect of yeast inoculum density on the reduction rate was tested. As correlation between the color change rate and inoculum density was observed, approximate quantification of viable cells was possible. The assay would be of relevance to antifungal susceptibility testing in both planktonic and biofilm yeasts.

Screening and evaluation of the glucoside hydrolase activity in Saccharomyces and Brettanomyces brewing yeasts.

PubMed

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.

Spent yeast as natural source of functional food additives

PubMed

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

Yeasts from sub-Antarctic region: biodiversity, enzymatic activities and their potential as oleaginous microorganisms.

PubMed

Martinez, A; Cavello, I; Garmendia, G; Rufo, C; Cavalitto, S; Vero, S

2016-09-01

Various microbial groups are well known to produce a range of extracellular enzymes and other secondary metabolites. However, the occurrence and importance of investment in such activities have received relatively limited attention in studies of Antarctic soil microbiota. Sixty-one yeasts strains were isolated from King George Island, Antarctica which were characterized physiologically and identified at the molecular level using the D1/D2 region of rDNA. Fifty-eight yeasts (belonging to the genera Cryptococcus, Leucosporidiella, Rhodotorula, Guehomyces, Candida, Metschnikowia and Debaryomyces) were screened for extracellular amylolytic, proteolytic, esterasic, pectinolytic, inulolytic xylanolytic and cellulolytic activities at low and moderate temperatures. Esterase activity was the most common enzymatic activity expressed by the yeast isolates regardless the assay temperature and inulinase was the second most common enzymatic activity. No cellulolytic activity was detected. One yeast identified as Guehomyces pullulans (8E) showed significant activity across six of seven enzymes types tested. Twenty-eight yeast isolates were classified as oleaginous, being the isolate 8E the strain that accumulated the highest levels of saponifiable lipids (42 %).

The hydrolytic activity of esterases in the yeast Saccharomyces cerevisiae is strain dependent.

PubMed

Kwolek-Mirek, Magdalena; Bednarska, Sabina; Zadrąg-Tęcza, Renata; Bartosz, Grzegorz

2011-11-01

Ester precursors of fluorogenic or chromogenic probes are often employed in studies of yeast cell biology. This study was aimed at a comparison of the ability of several commonly used laboratory wild-type Saccharomyces cerevisiae strains to hydrolyse the following model esters: fluorescein diacetate, 2-naphthyl acetate, PNPA (p-nitrophenyl acetate) and AMQI (7-acetoxy-1-methylquinolinum iodide). In all the strains, the esterase activity was localized mainly to the cytosol. Considerable differences in esterase activity were observed between various wild-type laboratory yeast strains. The phase of growth also contributed to the variation in esterase activity of the yeast. This diversity implies the need for caution in using intracellularly hydrolysed probes for a comparison of yeast strains with various genetic backgrounds.

Effect of Specific Growth Rate on Fermentative Capacity of Baker’s Yeast

PubMed Central

Van Hoek, Pim; Van Dijken, Johannes P.; Pronk, Jack T.

1998-01-01

The specific growth rate is a key control parameter in the industrial production of baker’s yeast. Nevertheless, quantitative data describing its effect on fermentative capacity are not available from the literature. In this study, the effect of the specific growth rate on the physiology and fermentative capacity of an industrial Saccharomyces cerevisiae strain in aerobic, glucose-limited chemostat cultures was investigated. At specific growth rates (dilution rates, D) below 0.28 h−1, glucose metabolism was fully respiratory. Above this dilution rate, respirofermentative metabolism set in, with ethanol production rates of up to 14 mmol of ethanol · g of biomass−1 · h−1 at D = 0.40 h−1. A substantial fermentative capacity (assayed offline as ethanol production rate under anaerobic conditions) was found in cultures in which no ethanol was detectable (D < 0.28 h−1). This fermentative capacity increased with increasing dilution rates, from 10.0 mmol of ethanol · g of dry yeast biomass−1 · h−1 at D = 0.025 h−1 to 20.5 mmol of ethanol · g of dry yeast biomass−1 · h−1 at D = 0.28 h−1. At even higher dilution rates, the fermentative capacity showed only a small further increase, up to 22.0 mmol of ethanol · g of dry yeast biomass−1 · h−1 at D = 0.40 h−1. The activities of all glycolytic enzymes, pyruvate decarboxylase, and alcohol dehydrogenase were determined in cell extracts. Only the in vitro activities of pyruvate decarboxylase and phosphofructokinase showed a clear positive correlation with fermentative capacity. These enzymes are interesting targets for overexpression in attempts to improve the fermentative capacity of aerobic cultures grown at low specific growth rates. PMID:9797269

Partial purification of histone H3 proteolytic activity from the budding yeast Saccharomyces cerevisiae.

PubMed

Azad, Gajendra Kumar; Tomar, Raghuvir Singh

2016-06-01

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

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

PubMed

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.

Characterization of pectinase activity for enology from yeasts occurring in Argentine Bonarda grape.

PubMed

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

2015-01-01

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

Characterization of pectinase activity for enology from yeasts occurring in Argentine Bonarda grape

PubMed Central

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

2015-01-01

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

An Investigation into Rumen Fungal and Protozoal Diversity in Three Rumen Fractions, during High-Fiber or Grain-Induced Sub-Acute Ruminal Acidosis Conditions, with or without Active Dry Yeast Supplementation

PubMed Central

Ishaq, Suzanne L.; AlZahal, Ousama; Walker, Nicola; McBride, Brian

2017-01-01

Sub-acute ruminal acidosis (SARA) is a gastrointestinal functional disorder in livestock characterized by low rumen pH, which reduces rumen function, microbial diversity, host performance, and host immune function. Dietary management is used to prevent SARA, often with yeast supplementation as a pH buffer. Almost nothing is known about the effect of SARA or yeast supplementation on ruminal protozoal and fungal diversity, despite their roles in fiber degradation. Dairy cows were switched from a high-fiber to high-grain diet abruptly to induce SARA, with and without active dry yeast (ADY, Saccharomyces cerevisiae) supplementation, and sampled from the rumen fluid, solids, and epimural fractions to determine microbial diversity using the protozoal 18S rRNA and the fungal ITS1 genes via Illumina MiSeq sequencing. Diet-induced SARA dramatically increased the number and abundance of rare fungal taxa, even in fluid fractions where total reads were very low, and reduced protozoal diversity. SARA selected for more lactic-acid utilizing taxa, and fewer fiber-degrading taxa. ADY treatment increased fungal richness (OTUs) but not diversity (Inverse Simpson, Shannon), but increased protozoal richness and diversity in some fractions. ADY treatment itself significantly (P < 0.05) affected the abundance of numerous fungal genera as seen in the high-fiber diet: Lewia, Neocallimastix, and Phoma were increased, while Alternaria, Candida Orpinomyces, and Piromyces spp. were decreased. Likewise, for protozoa, ADY itself increased Isotricha intestinalis but decreased Entodinium furca spp. Multivariate analyses showed diet type was most significant in driving diversity, followed by yeast treatment, for AMOVA, ANOSIM, and weighted UniFrac. Diet, ADY, and location were all significant factors for fungi (PERMANOVA, P = 0.0001, P = 0.0452, P = 0.0068, Monte Carlo correction, respectively, and location was a significant factor (P = 0.001, Monte Carlo correction) for protozoa. Diet

An Investigation into Rumen Fungal and Protozoal Diversity in Three Rumen Fractions, during High-Fiber or Grain-Induced Sub-Acute Ruminal Acidosis Conditions, with or without Active Dry Yeast Supplementation.

PubMed

Ishaq, Suzanne L; AlZahal, Ousama; Walker, Nicola; McBride, Brian

2017-01-01

Sub-acute ruminal acidosis (SARA) is a gastrointestinal functional disorder in livestock characterized by low rumen pH, which reduces rumen function, microbial diversity, host performance, and host immune function. Dietary management is used to prevent SARA, often with yeast supplementation as a pH buffer. Almost nothing is known about the effect of SARA or yeast supplementation on ruminal protozoal and fungal diversity, despite their roles in fiber degradation. Dairy cows were switched from a high-fiber to high-grain diet abruptly to induce SARA, with and without active dry yeast (ADY, Saccharomyces cerevisiae ) supplementation, and sampled from the rumen fluid, solids, and epimural fractions to determine microbial diversity using the protozoal 18S rRNA and the fungal ITS1 genes via Illumina MiSeq sequencing. Diet-induced SARA dramatically increased the number and abundance of rare fungal taxa, even in fluid fractions where total reads were very low, and reduced protozoal diversity. SARA selected for more lactic-acid utilizing taxa, and fewer fiber-degrading taxa. ADY treatment increased fungal richness (OTUs) but not diversity (Inverse Simpson, Shannon), but increased protozoal richness and diversity in some fractions. ADY treatment itself significantly ( P < 0.05) affected the abundance of numerous fungal genera as seen in the high-fiber diet: Lewia, Neocallimastix , and Phoma were increased, while Alternaria, Candida Orpinomyces , and Piromyces spp. were decreased. Likewise, for protozoa, ADY itself increased Isotricha intestinalis but decreased Entodinium furca spp. Multivariate analyses showed diet type was most significant in driving diversity, followed by yeast treatment, for AMOVA, ANOSIM, and weighted UniFrac. Diet, ADY, and location were all significant factors for fungi (PERMANOVA, P = 0.0001, P = 0.0452, P = 0.0068, Monte Carlo correction, respectively, and location was a significant factor ( P = 0.001, Monte Carlo correction) for protozoa. Diet

Unexpected thermal destruction of dried, glass bead-immobilized microorganisms as a function of water activity.

PubMed

Laroche, C; Gervais, P

2003-05-01

To help us understand the factors and mechanisms implicated in the death of microorganisms or their resistance to temperature in a low water activity environment, microorganisms were dried on the surface of glass beads before being subjected to high temperatures for a short period followed by rapid cooling. Two microorganisms were studied: the yeast Saccharomyces cerevisiae and the bacterium Lactobacillus plantarum. Experiments were carried out at 150, 200, and 250 degrees C, with four durations of heat treatment and seven levels of initial water activity between 0.10 and 0.70. We observed an unexpected range of water activity, between 0.30 and 0.50, at which microorganisms were more resistant to the various treatments, with maximal viability at 0.35 for L. plantarum and 0.40 for S. cerevisiae.

Eighteen new oleaginous yeast species.

PubMed

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

2016-07-01

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

Yeast and yeast-like fungi associated with dry indehiscent fruits of Nothofagus nervosa in Patagonia, Argentina.

PubMed

Fernández, Natalia V; Mestre, M Cecilia; Marchelli, Paula; Fontenla, Sonia B

2012-04-01

Nothofagus nervosa (Raulí) is a native tree species that yields valuable timber. It was overexploited in the past and is currently included in domestication and conservation programs. Several research programs have focused on the characterization of epiphytic microorganisms because it has been demonstrated that they can affect plant-pathogen interactions and/or promote plant growth. Although the microbial ecology of leaves has been well studied, less is known about microorganisms occurring on seeds and noncommercial fruits. In this work, we analyzed the yeast and yeast-like fungi present on N. nervosa fruits destined for the propagation of this species, as well as the effects of fruit preservation and seed dormancy-breaking processes on fungal diversity. Morphological and molecular methods were used, and differences between fungal communities were analyzed using a similarity index. A total of 171 isolates corresponding to 17 species were recovered, most of which belong to the phylum Ascomycota. The majority of the species develop mycelia, produce pigments and mycosporines, and these adaptation strategies are discussed. It was observed that the preservation process considerably reduced yeast and yeast-like fungal diversity. This is the first study concerning microbial communities associated with this ecologically and economically important species, and the information presented is relevant to domestication programs. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Tanshinones extend chronological lifespan in budding yeast Saccharomyces cerevisiae.

PubMed

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

2014-10-01

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

Effects of dietary supplementation of active dried yeast on fecal methanogenic archaea diversity in dairy cows.

PubMed

Jin, Dingxing; Kang, Kun; Wang, Hongze; Wang, Zhisheng; Xue, Bai; Wang, Lizhi; Xu, Feng; Peng, Quanhui

2017-04-01

This study aimed to investigate the effects of dietary supplementation of different dosages of active dried yeast (ADY) on the fecal methanogenic archaea community of dairy cattle. Twelve multiparous, healthy, mid-lactating Holstein dairy cows (body weight: 584 ± 23.2 kg, milk produced: 26.3 ± 1.22 kg/d) were randomly assigned to one of three treatments (control, ADY2, and ADY4) according to body weight with four replicates per treatment. Cows in the control group were fed conventional rations without ADY supplementation, while cows in the ADY2 and ADY4 group were fed rations supplemented with ADY at 2 or 4 g/d/head. Real-time PCR analysis showed the populations of total methanogens in the feces were significantly decreased (P < 0.05) in the ADY4 group compared with control. High-throughput sequencing technology was applied to examine the differences in methanogenic archaea diversity in the feces of the three treatment groups. A total of 155,609 sequences were recovered (a mean of 12,967 sequences per sample) from the twelve fecal samples, which consisted of a number of operational taxonomic units (OTUs) ranging from 1451 to 1,733, were assigned to two phyla, four classes, five orders, five families and six genera. Bioinformatic analyses illustrated that the natural fecal archaeal community of the control group was predominated by Methanobrevibacter (86.9% of the total sequence reads) and Methanocorpusculum (10.4%), while the relative abundance of the remaining four genera were below 1% with Methanosphaera comprising 0.8%, Thermoplasma composing 0.4%, and the relative abundance of Candidatus Nitrososphaera and Halalkalicoccus being close to zero. At the genus level, the relative abundances of Methanocorpusculum and Thermoplasma were increased (P < 0.05) with increasing dosage of ADY. Conversely, the predominant methanogen genus Methanobrevibacter was decreased with ADY dosage (P < 0.05). Dietary supplementation of ADY had no significant effect (P�

Impact of yeast starter formulations on the production of volatile compounds during wine fermentation.

PubMed

Romano, Patrizia; Pietrafesa, Rocchina; Romaniello, Rossana; Zambuto, Marianna; Calabretti, Antonella; Capece, Angela

2015-01-01

The most diffused starter formulation in winemaking is actually represented by active dry yeast (ADY). Spray-drying has been reported as an appropriate preservation method for yeast and other micro-organisms. Despite the numerous advantages of this method, the high air temperatures used can negatively affect cell viability and the fermentative performance of dried cells. In the present study, 11 wine S. cerevisiae strains (both indigenous and commercial) were submitted to spray-drying; different process conditions were tested in order to select the conditions allowing the highest strain survival. The strains exhibited high variability for tolerance to spray-drying treatment. Selected strains were tested in fermentation at laboratory scale in different formulations (free fresh cells, free dried cells, immobilized fresh cells and immobilized dried cells), in order to assess the influence of starter formulation on fermentative fitness of strains and aromatic quality of wine. The analysis of volatile fraction in the experimental wines produced by selected strains in different formulations allowed identification of > 50 aromatic compounds (alcohols, esters, ketones, aldehydes and terpenes). The results obtained showed that the starter formulation significantly influenced the content of volatile compounds. In particular, the wines obtained by strains in dried forms (as both free and immobilized cells) contained higher numbers of volatile compounds than wines obtained from fresh cells. Copyright © 2014 John Wiley & Sons, Ltd.

Drying behaviour, effective diffusivity and energy of activation of olive leaves dried by microwave, vacuum and oven drying methods

NASA Astrophysics Data System (ADS)

Elhussein, Elaf Abdelillah Ali; Şahin, Selin

2018-07-01

Drying is the crucial food processing for bioactive components from plant materials before strating extraction in addition to preservation of raw plant materials during storage period. Olive leaves were dried by various methods such as microwave drying (MD), oven drying (OD) and vacuum drying (VD) at several temperature values in the present study. Mathematical models allow to develop, design and control the processes. 14 emprical equations were used to estimate the drying behaviour and the time required for drying. Convenience of the models were evaluated according to the correlation coefficient ( R 2 ), varience ( S 2 ) and root mean square deviation ( D RMS ). On the other hand, the effective diffusion coefficient and energy for activation were also calculated. Effects of the drying methods on the total phenolic (TPC), flavonoid (TFC) and oleuropein contents and free radical scavenging activity (FRSA) of the olive leaves were also investigated to take into considiration the quality of the dried product. MD has proved to be the fastest drying method having the highest effective diffusivity and the lowest activation energy with a more qualitive product.

Drying behaviour, effective diffusivity and energy of activation of olive leaves dried by microwave, vacuum and oven drying methods

NASA Astrophysics Data System (ADS)

Elhussein, Elaf Abdelillah Ali; Şahin, Selin

2018-01-01

Drying is the crucial food processing for bioactive components from plant materials before strating extraction in addition to preservation of raw plant materials during storage period. Olive leaves were dried by various methods such as microwave drying (MD), oven drying (OD) and vacuum drying (VD) at several temperature values in the present study. Mathematical models allow to develop, design and control the processes. 14 emprical equations were used to estimate the drying behaviour and the time required for drying. Convenience of the models were evaluated according to the correlation coefficient (R 2 ), varience (S 2 ) and root mean square deviation (D RMS ). On the other hand, the effective diffusion coefficient and energy for activation were also calculated. Effects of the drying methods on the total phenolic (TPC), flavonoid (TFC) and oleuropein contents and free radical scavenging activity (FRSA) of the olive leaves were also investigated to take into considiration the quality of the dried product. MD has proved to be the fastest drying method having the highest effective diffusivity and the lowest activation energy with a more qualitive product.

Biodiversity of yeast mycobiota in "sucuk," a traditional Turkish fermented dry sausage: phenotypic and genotypic identification, functional and technological properties.

PubMed

Ozturk, Ismet; Sagdic, Osman

2014-11-01

In this study, yeasts from Turkish fermented sucuks were identified and their functional and technological properties were evaluated. Two hundred fifty-five yeast isolates were obtained from 35 different sucuk samples from different regions of Turkey. The yeast isolates were determined as genotypic using 2 different polymerase chain reaction (PCR) methods (rep-PCR and RAPD-PCR). Functional and technological properties of including proteolytic, lipolytic, and catalase activities, tolerance to NaCl and bile, as well as growing rates at different temperature and pH conditions selected yeast strains were also evaluated. Candida zeylanoides and Debaryomyces hansenii were dominant strains in sucuk samples. All C. zeylanoides and D. hansenii tested could grow at the condition of 15% NaCl and 0.3% bile salt. However, none of the strains were able to grow at 37 °C, even though catalase activity, weak proteolytic and lipolytic activities was still observed. D. hansenii were able to grow only at pH 3, while some of C. zeylanoides could grow at lower pH levels (pH 2). Three and 4 strains of C. zeylanoides showed β-hemolysis activity and nitrate reduction ability to nitrite, respectively. D. hansenii did not have properties, which are β-hemolysis, nitrate reduction, or hydrogen sulfide production. Overall, diverse yeast mycobiota present in Turkish fermented sucuk and their functional and technological properties were revealed with this study. © 2014 Institute of Food Technologists®

A Simple Laboratory Exercise Illustrating Active Transport in Yeast Cells.

ERIC Educational Resources Information Center

Stambuk, Boris U.

2000-01-01

Describes a simple laboratory activity illustrating the chemiosmotic principles of active transport in yeast cells. Demonstrates the energy coupling mechanism of active a-glucoside uptake by Saccaromyces cerevisiae cells with a colorimetric transport assay using very simple equipment. (Contains 22 references.) (Author/YDS)

Quality and Antioxidant Activity of Buckwheat-Based Cookies Designed for a Raw Food Vegan Diet as Affected by Moderate Drying Temperature.

PubMed

Brožková, Iveta; Dvořáková, Veronika; Michálková, Kateřina; Červenka, Libor; Velichová, Helena

2016-12-01

Buckwheat cookies with various ingredients for raw food vegan diet are usually prepared by soaking them in water at ambient temperature followed by drying at moderate temperature. The aim of this study was to examine the temperature effect on the microbiological quality, antioxidant properties and oxidative stability of lipids of final dried samples. The mixture of ingredients was soaked for 20 h in distilled water, and then cookies were formed and dried in air-forced oven at constant temperature in the range from 40 to 60 °C. Total viable counts, fungi, yeasts, coliform and aerobic spore-forming bacteria counts were evaluated in dried samples and were found to decrease during drying at 50 and 60 °C. Antioxidant activity was determined by DPPH and ABTS assays, and the former showed the highest value at 40 °C. Superoxide dismutase activity was also higher at 40 °C in comparison with that at 60 °C. The percentage of lipid peroxidation inhibition increased with the increase in drying temperature until 4th day of incubation. While peroxide value was significantly higher in samples dried at 40 °C, TBARS values did not show significant changes during the drying process. The results of this study suggest that drying buckwheat-based cookies at 40 °C retained their good antioxidant properties but represent a potentially serious microbial hazard.

Impact of mild heat treatments on induction of thermotolerance in the biocontrol yeast Candida sake CPA-1 and viability after spray-drying.

PubMed

Cañamás, T P; Viñas, I; Usall, J; Magan, N; Solsona, C; Teixidó, N

2008-03-01

The objective of this study was to examine the induction of thermotolerance in the biocontrol agent Candida sake CPA-1 cells by mild heat treatments to enhanced survival of formulations using spray-drying. The possible role of heat-shock proteins (HSPs) biosynthesis in induced thermotolerance and the role of sugars and sugar alcohols were also determined. Studies were conducted on C. sake cells grown in molasses medium and exposed to mild temperatures of 30 and 33 degrees C during mid- (16 h), late-exponential (24 h), early- (30 h) and mid-stationary (36 h) growth phases. The effect on viability was determined both before and after spray-drying. Cycloheximide and chloramphenicol were used to examine the role of HSPs and HPLC was used to analyse the accumulation of sugar and sugar alcohols. The results indicate that both temperatures induced thermotolerance in cells of C. sake. Mild heat-adapted cells at 33 degrees C in the early- or mid-stationary phases had survival values after spray-drying significantly higher (P yeasts such as C. sake. However, this does not improve survival of cells exposed to spray-drying sufficiently to consider this a suitable formulation method for this biocontrol agent. HSPs, sugars and sugar polyols were not directly responsible for induced thermotolerance in yeast cells. This type of information can be effectively applied to improve the viability of cells in the process of formulation.

Factors influencing ruminal bacterial community diversity and composition and microbial fibrolytic enzyme abundance in lactating dairy cows with a focus on the role of active dry yeast.

PubMed

AlZahal, Ousama; Li, Fuyong; Guan, Le Luo; Walker, Nicola D; McBride, Brian W

2017-06-01

The objective of the current study was to employ a DNA-based sequencing technology to study the effect of active dry yeast (ADY) supplementation, diet type, and sample location within the rumen on rumen bacterial community diversity and composition, and to use an RNA-based method to study the effect of ADY supplementation on rumen microbial metabolism during high-grain feeding (HG). Our previous report demonstrated that the supplementation of lactating dairy cows with ADY attenuated the effect of subacute ruminal acidosis. Therefore, we used samples from that study, where 16 multiparous, rumen-cannulated lactating Holstein cows were randomly assigned to 1 of 2 dietary treatments: ADY (Saccharomyces cerevisiae strain Y1242, 80 billion cfu/animal per day) or control (carrier only). Cows received a high-forage diet (77:23, forage:concentrate), then were abruptly switched to HG (49:51, forage:concentrate). Rumen bacterial community diversity and structure were highly influenced by diet and sampling location (fluid, solids, epimural). The transition to HG reduced bacterial diversity, but epimural bacteria maintained a greater diversity than fluid and solids. Analysis of molecular variance indicated a significant separation due to diet × sampling location, but not due to treatment. Across all samples, the analysis yielded 6,254 nonsingleton operational taxonomic units (OTU), which were classified into several phyla: mainly Firmicutes, Bacteroidetes, Fibrobacteres, Tenericutes, and Proteobacteria. High forage and solids were dominated by OTU from Fibrobacter, whereas HG and fluid were dominated by OTU from Prevotella. Epimural samples, however, were dominated in part by Campylobacter. Active dry yeast had no effect on bacterial community diversity or structure. The phylum SR1 was more abundant in all ADY samples regardless of diet or sampling location. Furthermore, on HG, OTU2 and OTU3 (both classified into Fibrobacter succinogenes) were more abundant with ADY in fluid

Yeast for virus research

PubMed Central

Zhao, Richard Yuqi

2017-01-01

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

The presence of Enterococcus, coliforms and E. coli in a commercial yeast manufacturing process.

PubMed

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

2004-07-01

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

The contribution of glutathione to the destabilizing effect of yeast on wheat dough.

PubMed

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

2015-04-15

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

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

PubMed

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

2016-01-01

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

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

PubMed Central

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

2000-01-01

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

Potential for a mycotoxin deactivator to improve growth and performance of rainbow trout fed high levels of an ethanol industry co-Product, grain distiller’s dried yeast

USDA-ARS?s Scientific Manuscript database

Co-products from the production of fuel ethanol may have the potential to be used as protein sources for Rainbow Trout Oncorhynchus mykiss if dietary supplementation strategies that can maintain fish performance can be identified. A random sample of one such co-product, grain distiller’s dried yeast...

Mechanisms of Contact-Mediated Killing of Yeast Cells on Dry Metallic Copper Surfaces▿

PubMed Central

Quaranta, Davide; Krans, Travis; Santo, Christophe Espírito; Elowsky, Christian G.; Domaille, Dylan W.; Chang, Christopher J.; Grass, Gregor

2011-01-01

Surfaces made of copper or its alloys have strong antimicrobial properties against a wide variety of microorganisms. However, the molecular mode of action responsible for the antimicrobial efficacy of metallic copper is not known. Here, we show that dry copper surfaces inactivate Candida albicans and Saccharomyces cerevisiae within minutes in a process called contact-mediated killing. Cellular copper ion homeostasis systems influenced the kinetics of contact-mediated killing in both organisms. Deregulated copper ion uptake through a hyperactive S. cerevisiae Ctr1p (ScCtr1p) copper uptake transporter in Saccharomyces resulted in faster inactivation of mutant cells than of wild-type cells. Similarly, lack of the C. albicans Crp1p (CaCrp1p) copper-efflux P-type ATPase or the metallothionein CaCup1p caused more-rapid killing of Candida mutant cells than of wild-type cells. Candida and Saccharomyces took up large quantities of copper ions as soon as they were in contact with copper surfaces, as indicated by inductively coupled plasma mass spectroscopy (ICP-MS) analysis and by the intracellular copper ion-reporting dye coppersensor-1. Exposure to metallic copper did not cause lethality through genotoxicity, deleterious action on a cell's genetic material, as indicated by a mutation assay with Saccharomyces. Instead, toxicity mediated by metallic copper surfaces targeted membranes in both yeast species. With the use of Live/Dead staining, onset of rapid and extensive cytoplasmic membrane damage was observed in cells from copper surfaces. Fluorescence microscopy using the indicator dye DiSBaC2(3) indicated that cell membranes were depolarized. Also, during contact-mediated killing, vacuoles first became enlarged and then disappeared from the cells. Lastly, in metallic copper-stressed yeasts, oxidative stress in the cytoplasm and in mitochondria was elevated. PMID:21097600

Mitochondrial metabolism and stress response of yeast: Applications in fermentation technologies.

PubMed

Kitagaki, Hiroshi; Takagi, Hiroshi

2014-04-01

Mitochondria are sites of oxidative respiration. During sake brewing, sake yeasts are exposed to long periods of hypoxia; the structure, role, and metabolism of mitochondria of sake yeasts have not been studied in detail. It was first elucidated that the mitochondrial structure of sake yeast transforms from filamentous to dotted structure during sake brewing, which affects malate metabolism. Based on the information of yeast mitochondria during sake brewing, practical technologies have been developed; (i) breeding pyruvate-underproducing sake yeast by the isolation of a mutant resistant to an inhibitor of mitochondrial pyruvate transport; and (ii) modifying malate and succinate production by manipulating mitochondrial activity. During the bread-making process, baker's yeast cells are exposed to a variety of baking-associated stresses, such as freeze-thaw, air-drying, and high sucrose concentrations. These treatments induce oxidative stress generating reactive oxygen species due to mitochondrial damage. A novel metabolism of proline and arginine catalyzed by N-acetyltransferase Mpr1 in the mitochondria eventually leads to synthesis of nitric oxide, which confers oxidative stress tolerance on yeast cells. The enhancement of proline and arginine metabolism could be promising for breeding novel baker's yeast strains that are tolerant to multiple baking-associated stresses. These new and practical methods provide approaches to improve the processes in the field of industrial fermentation technologies. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Contribution of yeast and base wine supplementation to sparkling wine composition.

PubMed

Martí-Raga, Maria; Martín, Valentina; Gil, Mariona; Sancho, Marta; Zamora, Fernando; Mas, Albert; Beltran, Gemma

2016-12-01

The differential characteristic of sparkling wine is the formation of foam, which is dependent, among other factors, on yeast autolysis, aging and oenological practices. In this study, we analyzed the effects of yeast strain, nutrient supplementation to the base wine and aging process on the sparkling wine composition and its foamability. We determined that the addition of inorganic nitrogen promoted nitrogen liberation to the extracellular medium, while the addition of inactive dry yeast to the base wine caused an increase in the polysaccharide concentration and foaming properties of the sparkling wine. The use of synthetic and natural base wines allowed us to discriminate that the differences in high-molecular-weight polysaccharides and oligosaccharides could be attributed to the yeast cells and that the higher nitrogen content in the natural wine could be due to external proteolysis. The practices of nitrogen addition and supplementation of inactive dry yeast could modulate the main characteristics of the sparkling wine and be a critical element for the design of this kind of wine. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Alcohol Dehydrogenase Activities of Wine Yeasts in Relation to Higher Alcohol Formation

PubMed Central

Singh, Rajendra; Kunkee, Ralph E.

1976-01-01

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

Fructanase and fructosyltransferase activity of non-Saccharomyces yeasts isolated from fermenting musts of Mezcal.

PubMed

Arrizon, Javier; Morel, Sandrine; Gschaedler, Anne; Monsan, Pierre

2012-04-01

Fructanase and fructosyltransferase are interesting for the tequila process and prebiotics production (functional food industry). In this study, one hundred thirty non-Saccharomyces yeasts isolated from "Mezcal de Oaxaca" were screened for fructanase and fructosyltransferase activity. On solid medium, fifty isolates grew on Agave tequilana fructans (ATF), inulin or levan. In liquid media, inulin and ATF induced fructanase activities of between 0.02 and 0.27U/ml depending of yeast isolate. High fructanase activity on sucrose was observed for Kluyveromyces marxianus and Torulaspora delbrueckii, while the highest fructanase activity on inulin and ATF was observed for Issatchenkia orientalis, Cryptococcus albidus, and Candida apicola. Zygosaccharomyces bisporus and Candida boidinii had a high hydrolytic activity on levan. Sixteen yeasts belonging to K. marxianus, T. delbrueckii and C. apicola species were positive for fructosyltransferase activity. Mezcal microbiota proved to showed to be a source for new fructanase and fructosyltransferases with potential application in the tequila and food industry. Copyright © 2012 Elsevier Ltd. All rights reserved.

Enhancement of the proline and nitric oxide synthetic pathway improves fermentation ability under multiple baking-associated stress conditions in industrial baker's yeast

PubMed Central

2012-01-01

Background During the bread-making process, industrial baker's yeast, mostly Saccharomyces cerevisiae, is exposed to baking-associated stresses, such as air-drying and freeze-thaw stress. These baking-associated stresses exert severe injury to yeast cells, mainly due to the generation of reactive oxygen species (ROS), leading to cell death and reduced fermentation ability. Thus, there is a great need for a baker's yeast strain with higher tolerance to baking-associated stresses. Recently, we revealed a novel antioxidative mechanism in a laboratory yeast strain that is involved in stress-induced nitric oxide (NO) synthesis from proline via proline oxidase Put1 and N-acetyltransferase Mpr1. We also found that expression of the proline-feedback inhibition-less sensitive mutant γ-glutamyl kinase (Pro1-I150T) and the thermostable mutant Mpr1-F65L resulted in an enhanced fermentation ability of baker's yeast in bread dough after freeze-thaw stress and air-drying stress, respectively. However, baker's yeast strains with high fermentation ability under multiple baking-associated stresses have not yet been developed. Results We constructed a self-cloned diploid baker's yeast strain with enhanced proline and NO synthesis by expressing Pro1-I150T and Mpr1-F65L in the presence of functional Put1. The engineered strain increased the intracellular NO level in response to air-drying stress, and the strain was tolerant not only to oxidative stress but also to both air-drying and freeze-thaw stresses probably due to the reduced intracellular ROS level. We also showed that the resultant strain retained higher leavening activity in bread dough after air-drying and freeze-thaw stress than that of the wild-type strain. On the other hand, enhanced stress tolerance and fermentation ability did not occur in the put1-deficient strain. This result suggests that NO is synthesized in baker's yeast from proline in response to oxidative stresses that induce ROS generation and that increased NO

Enhancement of the proline and nitric oxide synthetic pathway improves fermentation ability under multiple baking-associated stress conditions in industrial baker's yeast.

PubMed

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

2012-04-01

During the bread-making process, industrial baker's yeast, mostly Saccharomyces cerevisiae, is exposed to baking-associated stresses, such as air-drying and freeze-thaw stress. These baking-associated stresses exert severe injury to yeast cells, mainly due to the generation of reactive oxygen species (ROS), leading to cell death and reduced fermentation ability. Thus, there is a great need for a baker's yeast strain with higher tolerance to baking-associated stresses. Recently, we revealed a novel antioxidative mechanism in a laboratory yeast strain that is involved in stress-induced nitric oxide (NO) synthesis from proline via proline oxidase Put1 and N-acetyltransferase Mpr1. We also found that expression of the proline-feedback inhibition-less sensitive mutant γ-glutamyl kinase (Pro1-I150T) and the thermostable mutant Mpr1-F65L resulted in an enhanced fermentation ability of baker's yeast in bread dough after freeze-thaw stress and air-drying stress, respectively. However, baker's yeast strains with high fermentation ability under multiple baking-associated stresses have not yet been developed. We constructed a self-cloned diploid baker's yeast strain with enhanced proline and NO synthesis by expressing Pro1-I150T and Mpr1-F65L in the presence of functional Put1. The engineered strain increased the intracellular NO level in response to air-drying stress, and the strain was tolerant not only to oxidative stress but also to both air-drying and freeze-thaw stresses probably due to the reduced intracellular ROS level. We also showed that the resultant strain retained higher leavening activity in bread dough after air-drying and freeze-thaw stress than that of the wild-type strain. On the other hand, enhanced stress tolerance and fermentation ability did not occur in the put1-deficient strain. This result suggests that NO is synthesized in baker's yeast from proline in response to oxidative stresses that induce ROS generation and that increased NO plays an important

Coupling Binding to Catalysis: Using Yeast Cell Surface Display to Select Enzymatic Activities.

PubMed

Zhang, Keya; Bhuripanyo, Karan; Wang, Yiyang; Yin, Jun

2015-01-01

We find yeast cell surface display can be used to engineer enzymes by selecting the enzyme library for high affinity binding to reaction intermediates. Here we cover key steps of enzyme engineering on the yeast cell surface including library design, construction, and selection based on magnetic and fluorescence-activated cell sorting.

Kluyveromyces wickerhamii killer toxin: purification and activity towards Brettanomyces/Dekkera yeasts in grape must.

PubMed

Comitini, Francesca; Ciani, Maurizio

2011-03-01

Brettanomyces/Dekkera yeasts have been identified as part of the grape yeast flora. They are well known for colonizing the cellar environmental and spoiling wines, causing haze, turbidity and strong off-flavours in wines and enhancing the volatile acidity. As the general practices applied to combat Brettanomyces/Dekkera yeasts are not particularly appropriate during wine ageing and storage, a biological alternative to curtailing their growth would be welcomed in winemaking. In this study, we investigated the Kluyveromyces wickerhamii killer toxin (Kwkt) that is active against Brettanomyces/Dekkera spoilage yeasts. Purification procedures allowed the identification of Kwkt as a protein with an apparent molecular mass of 72 kDa and without any glycosyl residue. Interestingly, purified Kwkt has fungicidal effects at low concentrations under the physicochemical conditions of winemaking. The addition of 40 and 80 mg L(-1) purified Kwkt showed efficient antispoilage effects, controlling both growth and metabolic activity of sensitive spoilage yeasts. At these two killer toxin concentrations, compounds known to contribute to the 'Brett' character of wines, such as ethyl phenols, were not produced. Thus, purified Kwkt appears to be a suitable biological strategy to control Brettanomyces/Dekkera yeasts during fermentation, wine ageing and storage. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Chemical Synthesis of Sulfated Yeast (Saccharomyces cerevisiae) Glucans and Their In Vivo Antioxidant Activity.

PubMed

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

2017-07-28

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

Synthesis of polypyrrole within the cell wall of yeast by redox-cycling of [Fe(CN)6](3-)/[Fe(CN)6](4-).

PubMed

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

2016-02-01

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

Extracellular Polysaccharides Produced by Yeasts and Yeast-Like Fungi

NASA Astrophysics Data System (ADS)

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

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

Evaluation of commercially available enzymes, probiotics, or yeast on apparent total-tract nutrient digestion and growth in nursery and finishing pigs fed diets containing corn dried distillers grains with solubles

USDA-ARS?s Scientific Manuscript database

The ability of enzymes, direct fed microbials, or yeast to enhance nutrient utilization or growth performance in nursery or finishing pigs fed diets containing increased levels of corn fiber from dried distillers grains with solubles (DDGS) is largely unknown. Ten commercially available feed additiv...

Hypoglycemic activity of dried extracts of Bauhinia forficata Link.

PubMed

da Cunha, A M; Menon, S; Menon, R; Couto, A G; Bürger, C; Biavatti, M W

2010-01-01

Leaves of the pantropical genus Bauhinia (Fabaceae) are known popularly as cow's foot, due to their unique characteristic bilobed aspect. The species Bauhinia forficata (Brazilian Orchid-tree) is widely used in folk medicine as an antidiabetic. The present work investigates the hypoglycemic activity of the dried extracts of Bauhinia forficata leaves in vivo, as well as the influence of the drying and granulation processes on this activity. The fluid extract was dried to generate oven-dried (ODE), spray-dried (SDE) and wet granulation (WGE) extracts, with the aid of colloidal silicon dioxide and/or cellulose:lactose mixture. The dried extracts were characterized by spectrophotometric, chromatographic and photo microscopy image analysis. 200 mg/kg body wt., p.o. of each dried product were administered orally to male Wistar rats over 7 days old, for biomonitoring of the hypoglycemic activity profile. The effect of the extracts was studied in STZ-induced diabetic rats. After 7 days of treatment, fasting glucose was determined, and the livers were removed, dried on tissue paper, weighed, and stored at -20 degrees C to estimate hepatic glycogen. Our results show that spray-drying or oven-drying processes applied to B. forficata extracts did not significantly alter its flavonoid profile or its hypoglycemic activity. Indeed, the dried extracts of B. forficata act differently from glibenclamide. Despite the lower active content in WGE, because of the higher concentration of adjuvants, the use of the granulation process improved the manufacturing properties of the ODE, making this material more appropriate for use in tablets or capsules.

Efficient activation of transcription in yeast by the BPV1 E2 protein.

PubMed Central

Stanway, C A; Sowden, M P; Wilson, L E; Kingsman, A J; Kingsman, S M

1989-01-01

The full-length gene product encoded by the E2 open reading frame (ORF) of bovine papillomavirus type 1 (BPV1) is a transcriptional transactivator. It is believed to mediate its effect on the BPV1 long control region (LCR) by binding to motifs with the consensus sequence ACCN6GGT. The minimal functional cis active site, called the E2 response element (E2RE), in mammalian cells comprises two copies of this motif. Here we have shown that E2 can function in Saccharomyces cerevisiae by placing an E2RE upstream of a synthetic yeast assay promoter which consists of a TATA motif and an mRNA initiation site, spaced correctly. This E2RE-minimal promoter is only transcriptionally active in the presence of E2 protein and the resulting mRNA is initiated at the authentic start site. This is the first report of a mammalian viral transactivator functioning in yeast. The level of activation by E2 via the E2RE was the same as observed with the highly efficient authentic PGK promoter where the upstream activation sequence is composed of three distinct elements. Furthermore a single E2 motif which is insufficient in mammalian cells as an activation site was as efficiently utilized in yeast as the E2RE (2 motifs). Previous studies have shown that mammalian cellular activators can function in yeast and our data now extend this to viral-specific activators. Our data indicate however that while the mechanism of transactivation is broadly conserved there may be significant differences at the detailed level. Images PMID:2539584

Evaluation of Brewer's spent yeast to produce flavor enhancer nucleotides: influence of serial repitching.

PubMed

Vieira, Elsa; Brandão, Tiago; Ferreira, Isabel M P L V O

2013-09-18

The present work evaluates the influence of serial yeast repitching on nucleotide composition of brewer's spent yeast extracts produced without addition of exogenous enzymes. Two procedures for disrupting cell walls were compared, and the conditions for low-cost and efficient RNA hydrolysis were selected. A HILIC methodology was validated for the quantification of nucleotides and nucleosides in yeast extracts. Thirty-seven samples of brewer's spent yeast ( Saccharomyces pastorianus ) organized according to the number of serial repitchings were analyzed. Nucleotides accounted for 71.1-88.2% of the RNA products; 2'AMP was the most abundant (ranging between 0.08 and 2.89 g/100 g dry yeast). 5'GMP content ranged between 0.082 and 0.907 g/100 g dry yeast. The sum of 5'GMP, 5'IMP, and 5'AMP represented between 25 and 32% of total nucleotides. This works highlights for the first time that although serial repitching influences the content of monophosphate nucleotides and nucleosides, the profiles of these RNA hydrolysis products are not affected.

Technological Development of Brewing in Domestic Refrigerator Using Freeze-Dried Raw Materials.

PubMed

Gialleli, Angelika-Ioanna; Ganatsios, Vassilios; Terpou, Antonia; Kanellaki, Maria; Bekatorou, Argyro; Koutinas, Athanasios A; Dimitrellou, Dimitra

2017-09-01

Development of a novel directly marketable beer brewed at low temperature in a domestic refrigerator combined with yeast immobilization technology is presented in this study. Separately, freeze-dried wort and immobilized cells of the cryotolerant yeast strain Saccharomyces cerevisiae AXAZ-1 on tubular cellulose were used in low-temperature fermentation (2, 5 and 7 °C). The positive effect of tubular cellulose during low-temperature brewing was examined, revealing that freeze-dried immobilized yeast cells on tubular cellulose significantly reduced the fermentation rates in contrast to freeze-dried free cells, although they are recommended for home-made beer production. Immobilization also enhanced the yeast resistance at low-temperature fermentation, reducing the minimum brewing temperature value from 5 to 2 °C. In the case of high-quality beer production, the effect of temperature and initial sugar concentration on the fermentation kinetics were assessed. Sensory enrichment of the produced beer was confirmed by the analysis of the final products, revealing a low diacetyl concentration, together with improved polyphenol content, aroma profile and clarity. The proposed process for beer production in a domestic refrigerator can easily be commercialized and applied by dissolving the content of two separate packages in tap water; one package containing dried wort and the other dried immobilized cells on tubular cellulose suspended in tap water.

Technological Development of Brewing in Domestic Refrigerator Using Freeze-Dried Raw Materials

PubMed Central

2017-01-01

Summary Development of a novel directly marketable beer brewed at low temperature in a domestic refrigerator combined with yeast immobilization technology is presented in this study. Separately, freeze-dried wort and immobilized cells of the cryotolerant yeast strain Saccharomyces cerevisiae AXAZ-1 on tubular cellulose were used in low-temperature fermentation (2, 5 and 7 °C). The positive effect of tubular cellulose during low-temperature brewing was examined, revealing that freeze-dried immobilized yeast cells on tubular cellulose significantly reduced the fermentation rates in contrast to freeze-dried free cells, although they are recommended for home-made beer production. Immobilization also enhanced the yeast resistance at low-temperature fermentation, reducing the minimum brewing temperature value from 5 to 2 °C. In the case of high-quality beer production, the effect of temperature and initial sugar concentration on the fermentation kinetics were assessed. Sensory enrichment of the produced beer was confirmed by the analysis of the final products, revealing a low diacetyl concentration, together with improved polyphenol content, aroma profile and clarity. The proposed process for beer production in a domestic refrigerator can easily be commercialized and applied by dissolving the content of two separate packages in tap water; one package containing dried wort and the other dried immobilized cells on tubular cellulose suspended in tap water. PMID:29089847

Performance evaluation of startup for a yeast membrane bioreactor (MBRy) treating landfill leachate.

PubMed

Amaral, Míriam C S; Gomes, Rosimeire F; Brasil, Yara L; Oliveira, Sílvia M A; Moravia, Wagner G

2017-12-06

The startup process of a membrane bioreactor inoculated with yeast biomass (Saccharomyces cerevisiae) and used in the treatment of landfill leachate was evaluated. The yeast membrane bioreactor (MBRy) was inoculated with an exogenous inoculum, a granulated active dry commercial bakers' yeast. The MBRy was successfully started up with a progressive increase in the landfill leachate percentage in the MBRy feed and the use of Sabouraud Dextrose Broth. The membrane plays an important role in the startup phase because of its full biomass retention and removal of organic matter. MBRy is a suitable and promising process to treat recalcitrant landfill leachate. After the acclimation period, the COD and NH 3 removal efficiency reached values of 72 ± 3% and 39 ± 2% respectively. MBRy shows a low membrane-fouling potential. The membrane fouling was influenced by soluble microbial products, extracellular polymeric substances, sludge particle size, and colloidal dissolved organic carbon.

Oxygen Consumption by Postfermentation Wine Yeast Lees: Factors Affecting Its Rate and Extent under Oenological Conditions

PubMed Central

Müller, Jonas; Schmidt, Dominik

2016-01-01

Summary Postfermentation wine yeast lees show antioxidant properties based on their ability to consume dissolved oxygen. The oxygen consumption capacity of suspended yeast lees obtained after fermentations with six commercial active dry yeast strains was investigated in model, white and red wines using fluorescence-based oxygen sensors operating in a nondestructive way. In model solution, the oxygen consumption rate of yeast lees was shown to depend on their amount, yeast strain, sulfur dioxide and temperature. It is slightly lower in red than in white wines. It is strongly decreased by current levels of free sulfur dioxide, thus excluding the complementary use of both as antioxidants in wine. However, in 25 randomly sampled white wines produced under commercial conditions, the rate and extent of oxygen consumption during the first six months of postfermentation had no significant correlation with any of these interacting factors, making it difficult to predict the actual antioxidant effect of yeast lees. In these wines, yeast lees consumed 0 to 47% of the dissolved oxygen. Although total oxygen consumption capacity of yeast lees is not a limiting factor under commercial winemaking conditions, their oxygen consumption proceeds at a limited rate that reduces but cannot totally prevent concomitant chemical oxidation of the wine. PMID:28115896

Oxygen Consumption by Postfermentation Wine Yeast Lees: Factors Affecting Its Rate and Extent under Oenological Conditions.

PubMed

Schneider, Volker; Müller, Jonas; Schmidt, Dominik

2016-12-01

Postfermentation wine yeast lees show antioxidant properties based on their ability to consume dissolved oxygen. The oxygen consumption capacity of suspended yeast lees obtained after fermentations with six commercial active dry yeast strains was investigated in model, white and red wines using fluorescence-based oxygen sensors operating in a nondestructive way. In model solution, the oxygen consumption rate of yeast lees was shown to depend on their amount, yeast strain, sulfur dioxide and temperature. It is slightly lower in red than in white wines. It is strongly decreased by current levels of free sulfur dioxide, thus excluding the complementary use of both as antioxidants in wine. However, in 25 randomly sampled white wines produced under commercial conditions, the rate and extent of oxygen consumption during the first six months of postfermentation had no significant correlation with any of these interacting factors, making it difficult to predict the actual antioxidant effect of yeast lees. In these wines, yeast lees consumed 0 to 47% of the dissolved oxygen. Although total oxygen consumption capacity of yeast lees is not a limiting factor under commercial winemaking conditions, their oxygen consumption proceeds at a limited rate that reduces but cannot totally prevent concomitant chemical oxidation of the wine.

Improvement of aromatic thiol release through the selection of yeasts with increased β-lyase activity.

PubMed

Belda, Ignacio; Ruiz, Javier; Navascués, Eva; Marquina, Domingo; Santos, Antonio

2016-05-16

The development of a selective medium for the rapid differentiation of yeast species with increased aromatic thiol release activity has been achieved. The selective medium was based on the addition of S-methyl-l-cysteine (SMC) as β-lyase substrate. In this study, a panel of 245 strains of Saccharomyces cerevisiae strains was tested for their ability to grow on YCB-SMC medium. Yeast strains with an increased β-lyase activity grew rapidly because of their ability to release ammonium from SMC in comparison to others, and allowed for the easy isolation and differentiation of yeasts with promising properties in oenology, or another field, for aromatic thiol release. The selective medium was also helpful for the discrimination between those S. cerevisiae strains, which present a common 38-bp deletion in the IRC7 sequence (present in around 88% of the wild strains tested and are likely to be less functional for 4-mercapto-4-methylpentan-2-one (4MMP) production), and those S. cerevisiae strains homozygous for the full-length IRC7 allele. The medium was also helpful for the selection of non-Saccharomyces yeasts with increased β-lyase activity. Based on the same medium, a highly sensitive, reproducible and non-expensive GC-MS method for the evaluation of the potential volatile thiol release by different yeast isolates was developed. Copyright © 2016 Elsevier B.V. All rights reserved.

21 CFR 344.12 - Ear drying aid active ingredient.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 5 2012-04-01 2012-04-01 false Ear drying aid active ingredient. 344.12 Section...) DRUGS FOR HUMAN USE TOPICAL OTIC DRUG PRODUCTS FOR OVER-THE-COUNTER HUMAN USE Active Ingredients § 344.12 Ear drying aid active ingredient. The active ingredient of the product consists of isopropyl...

21 CFR 344.12 - Ear drying aid active ingredient.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 5 2010-04-01 2010-04-01 false Ear drying aid active ingredient. 344.12 Section...) DRUGS FOR HUMAN USE TOPICAL OTIC DRUG PRODUCTS FOR OVER-THE-COUNTER HUMAN USE Active Ingredients § 344.12 Ear drying aid active ingredient. The active ingredient of the product consists of isopropyl...

21 CFR 344.12 - Ear drying aid active ingredient.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 5 2013-04-01 2013-04-01 false Ear drying aid active ingredient. 344.12 Section...) DRUGS FOR HUMAN USE TOPICAL OTIC DRUG PRODUCTS FOR OVER-THE-COUNTER HUMAN USE Active Ingredients § 344.12 Ear drying aid active ingredient. The active ingredient of the product consists of isopropyl...

21 CFR 344.12 - Ear drying aid active ingredient.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 5 2011-04-01 2011-04-01 false Ear drying aid active ingredient. 344.12 Section...) DRUGS FOR HUMAN USE TOPICAL OTIC DRUG PRODUCTS FOR OVER-THE-COUNTER HUMAN USE Active Ingredients § 344.12 Ear drying aid active ingredient. The active ingredient of the product consists of isopropyl...

21 CFR 344.12 - Ear drying aid active ingredient.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 5 2014-04-01 2014-04-01 false Ear drying aid active ingredient. 344.12 Section...) DRUGS FOR HUMAN USE TOPICAL OTIC DRUG PRODUCTS FOR OVER-THE-COUNTER HUMAN USE Active Ingredients § 344.12 Ear drying aid active ingredient. The active ingredient of the product consists of isopropyl...

Highly cold-active pectinases under wine-like conditions from non-Saccharomyces yeasts for enzymatic production during winemaking.

PubMed

Merín, M G; Morata de Ambrosini, V I

2015-05-01

The influence of oenological factors on cold-active pectinases from 15 preselected indigenous yeasts belonging to Aureobasidium pullulans, Filobasidium capsuligenum, Rhodotorula dairenensis, Cryptococcus saitoi and Saccharomyces cerevisiae was investigated. Pectinolytic enzymes were constitutive or partially constitutive; and high glucose concentration (200 g l(-1) ) did not affect or increased pectinase production at 12°C and pH 3·5 (up to 113·9 U mg(-1) ) only in A. pullulans strains. SO2 (120 mg l(-1) ) slightly affected the growth of A. pullulans strains but did not affect pectinase production levels. Ethanol (15%) barely affected pectinase activity of A. pullulans strains but diminished relative activity to 12-79% of basidiomycetous yeasts. Moreover, non-Saccharomyces strains showed promising properties of oenological interest. This study demonstrates that cold-active pectinases from some A. pullulans strains were able to remain active at glucose, ethanol and SO2 concentrations usually found in vinification, and suggests their potential use as processing aids for low-temperature winemaking. Nowadays, there is increasing interest in low-temperature winemaking. Nevertheless, commercial oenological pectinases, produced by fungi, are rarely active at low temperatures. Cold-active pectinases that are stable under vinification conditions are needed. This study indicated that cold-active and acid-tolerant pectinases from non-Saccharomcyes yeasts were able to remain active at glucose, ethanol and SO2 concentrations usually found in winemaking. Furthermore, not only are these yeasts a source of cold-active pectinases, but the yeasts themselves are also potential adjunct cultures for oenology to produce these enzymes during cold-winemaking. © 2015 The Society for Applied Microbiology.

Electron transport chain in a thermotolerant yeast.

PubMed

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

2017-04-01

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

Neural network analysis of electrodynamic activity of yeast cells around 1 kHz

NASA Astrophysics Data System (ADS)

Janca, R.

2011-12-01

This paper deals with data analysis of electrodynamic activity of two mutants of yeast cells, cell cycle of which is synchronized and non-synchronized, respectively. We used data already published by Jelinek et al. and treat them with data mining method based on the multilayer neural network. Intersection of data mining and statistical distribution of the noise shows significant difference between synchronized and non-synchronized yeasts not only in total power, but also discrete frequencies.

Effects of supplementing an active dry yeast product on rumen microbial community composition and on subsequent rumen fermentation of lactating cows in the mid-to-late lactation period.

PubMed

Uyeno, Yutaka; Akiyama, Kiyoshi; Hasunuma, Toshiya; Yamamoto, Hiroshi; Yokokawa, Hiroaki; Yamaguchi, Tsuneko; Kawashima, Kenji; Itoh, Minoru; Kushibiki, Shiro; Hirako, Makoto

2017-01-01

The effects of supplementing feed of cows in mid-to-late lactation with an active yeast product (Actisaf Sc 47) were evaluated using 15 Holstein cows in a replicated 3 × 3 Latin square design. The animals were fed a mixed ration with 33% neutral detergent fiber, consisting of timothy hay (29.8%), a commercial concentrate (70.0%) and commercial calcium triphosphate (0.2%), twice daily to meet 105% of their energy requirement. Yeast supplement was set at 0, 5 and 10 g per day over 21-day periods, each of which consisted of 14 days for adaptation followed by 7 days of data collection. Milking performance, plasma metabolite parameters, rumen volatile fatty acids, lipopolysaccharide and microbial properties were measured. Although there were no significant differences in feeding and milking performance or blood parameters associated with supplementation, the acetate to propionate ratio in the rumen fluid tended to decrease (P = 0.08). The population of Bacteroidetes tended to be less prominent (P = 0.07) and the fibrolytic bacterium Fibrobacter significantly increased (P < 0.05) in the rumen fluid of the yeast 10 g group compared with that of the control. These data suggest that effects of supplementing live yeast to cows in mid-to-late lactation may be limited to microbial composition and fermentation characteristics in the rumen. © 2016 Japanese Society of Animal Science.

The H159A mutant of yeast enolase 1 has significant activity.

PubMed

Brewer, J M; Holland, M J; Lebioda, L

2000-10-05

The function of His159 in the enolase mechanism is disputed. Recently, Vinarov and Nowak (Biochemistry (1999) 38, 12138-12149) prepared the H159A mutant of yeast enolase 1 and expressed this in Escherichia coli. They reported minimal (ca. 0.01% of the native value) activity, though the protein appeared to be correctly folded, according to its CD spectrum, tryptophan fluorescence, and binding of metal ion and substrate. We prepared H159A enolase using a multicopy plasmid and expressed the enzyme in yeast. Our preparations of H159A enolase have 0.2-0.4% of the native activity under standard assay conditions and are further activated by Mg(2+) concentrations above 1 mM to 1-1.5% of the native activity. Native enolase 1 (and enolase 2) are inhibited by such Mg(2+) concentrations. It is possible that His159 is necessary for correct folding of the enzyme and that expression in E. coli leads to largely misfolded protein. Copyright 2000 Academic Press.

Protein Folding Activity of the Ribosome is involved in Yeast Prion Propagation

PubMed Central

Blondel, Marc; Soubigou, Flavie; Evrard, Justine; Nguyen, Phu hai; Hasin, Naushaba; Chédin, Stéphane; Gillet, Reynald; Contesse, Marie-Astrid; Friocourt, Gaëlle; Stahl, Guillaume; Jones, Gary W.; Voisset, Cécile

2016-01-01

6AP and GA are potent inhibitors of yeast and mammalian prions and also specific inhibitors of PFAR, the protein-folding activity borne by domain V of the large rRNA of the large subunit of the ribosome. We therefore explored the link between PFAR and yeast prion [PSI+] using both PFAR-enriched mutants and site-directed methylation. We demonstrate that PFAR is involved in propagation and de novo formation of [PSI+]. PFAR and the yeast heat-shock protein Hsp104 partially compensate each other for [PSI+] propagation. Our data also provide insight into new functions for the ribosome in basal thermotolerance and heat-shocked protein refolding. PFAR is thus an evolutionarily conserved cell component implicated in the prion life cycle, and we propose that it could be a potential therapeutic target for human protein misfolding diseases. PMID:27633137

Fungal Presence in Selected Tree Nuts and Dried Fruits

PubMed Central

Tournas, VH; Niazi, NS; Kohn, JS

2015-01-01

Sixty-four tree nut samples (almonds, pecans, pine nuts, and walnuts) and 50 dried fruit samples (apricots, cranberries, papaya, pineapple, and raisins) were purchased from local supermarkets and analyzed for fungal contamination using conventional culture as well as molecular methods. The results of our study showed that the highest yeast and mold (YM) counts (5.34 log10 CFU g−1) were found in walnuts and the lowest in pecans. The most common mold in nuts was Aspergillus niger, relatively low numbers of A. flavus were found across the board, while Penicillium spp. were very common in pine nuts and walnuts. Low levels (2.00–2.84 log10 CFU g−1) of yeasts were recovered from only two pine nut samples. Fungal contamination in dried fruits was minimal (ranging from <2.00 to 3.86 log10 CFU g−1). The highest fungal levels were present in raisins. All papaya samples and the majority of cranberry, pineapple, and apricot samples were free of live fungi. The most common mold in dried fruits was A. niger followed by Penicillium spp. One apricot sample also contained low levels (2.00 log10 CFU g−1) of yeasts. PMID:26056470

Fungal Presence in Selected Tree Nuts and Dried Fruits.

PubMed

Tournas, V H; Niazi, N S; Kohn, J S

2015-01-01

Sixty-four tree nut samples (almonds, pecans, pine nuts, and walnuts) and 50 dried fruit samples (apricots, cranberries, papaya, pineapple, and raisins) were purchased from local supermarkets and analyzed for fungal contamination using conventional culture as well as molecular methods. The results of our study showed that the highest yeast and mold (YM) counts (5.34 log10 CFU g(-1)) were found in walnuts and the lowest in pecans. The most common mold in nuts was Aspergillus niger, relatively low numbers of A. flavus were found across the board, while Penicillium spp. were very common in pine nuts and walnuts. Low levels (2.00-2.84 log10 CFU g(-1)) of yeasts were recovered from only two pine nut samples. Fungal contamination in dried fruits was minimal (ranging from <2.00 to 3.86 log10 CFU g(-1)). The highest fungal levels were present in raisins. All papaya samples and the majority of cranberry, pineapple, and apricot samples were free of live fungi. The most common mold in dried fruits was A. niger followed by Penicillium spp. One apricot sample also contained low levels (2.00 log10 CFU g(-1)) of yeasts.

Live Yeast and Yeast Cell Wall Supplements Enhance Immune Function and Performance in Food-Producing Livestock: A Review †,‡

PubMed Central

Broadway, Paul R.; Carroll, Jeffery A.; Burdick Sanchez, Nicole C.

2015-01-01

More livestock producers are seeking natural alternatives to antibiotics and antimicrobials, and searching for supplements to enhance growth performance, and general animal health and well-being. Some of the compounds currently being utilized and studied are live yeast and yeast-based products derived from the strain Saccharomyces cerevisiae. These products have been reported to have positive effects both directly and indirectly on the immune system and its subsequent biomarkers, thereby mitigating negative effects associated with stress and disease. These yeast-based products have also been reported to simultaneously enhance growth and performance by enhancing dry matter intake (DMI) and average daily gain (ADG) perhaps through the establishment of a healthy gastrointestinal tract. These products may be especially useful in times of potential stress such as during birth, weaning, early lactation, and during the receiving period at the feedlot. Overall, yeast supplements appear to possess the ability to improve animal health and metabolism while decreasing morbidity, thereby enhancing profitability of these animals. PMID:27682097

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

PubMed

Dolezalova, Jaroslava; Rumlova, Lubomira

2014-11-01

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

Tolerance of budding yeast Saccharomyces cerevisiae to ultra high pressure

NASA Astrophysics Data System (ADS)

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

2014-05-01

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

Nitrile Metabolizing Yeasts

NASA Astrophysics Data System (ADS)

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

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

Functional adaptation between yeast actin and its cognate myosin motors.

PubMed

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

2011-09-02

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

Antifungal Activity of Propolis Against Yeasts Isolated From Blood Culture: In Vitro Evaluation.

PubMed

Mutlu Sariguzel, Fatma; Berk, Elife; Koc, Ayes Nedret; Sav, Hafize; Demir, Gonca

2016-09-01

Due to the failure of available antifungal agents in the treatment of candidemia and the toxic activities of these drugs, a lot of researches are being conducted to develop new nontoxic and effective antifungal agents for optimal control of fungal pathogens. The aim of this study is to evaluate the in vitro antifungal activity of propolis against yeasts isolated from the blood cultures of intensive care unit patients. Seventy-six strains were included in this study. The in vitro antifungal activity of propolis, fluconazole (FLU), and itraconazole (ITR) was investigated by the microdilution broth methods (CLSI guidelines M27-A3 for yeast). The propolis sample was collected from Kayseri, Turkey. Of the 76 isolates, 33 were identified as Candida albicans while 37 were C. parapsilosis, three were C. tropicalis, and three were identified as C. glabrata. The geometric mean range for MIC (μg/ml) with regard to all isolates was 0.077 to 3 μg/ml for FLU and ITR, and 0.375 to 0.70 μg/ml for propolis. It was shown that propolis had significant antifungal activity against all Candida strains and the MIC range of propolis was determined as 0185 to 3 μg/ml. This study demonstrated that propolis had significant antifungal activity against yeasts isolated from blood culture compared with FLU and ITR. The propolis MIC in azole-resistant strains such as C. glabrata was found lower than the FLU MIC. © 2015 Wiley Periodicals, Inc.

Enhanced phytate dephosphorylation by using Candida melibiosica yeast-based biofuel cell.

PubMed

Hubenova, Yolina; Georgiev, Danail; Mitov, Mario

2014-10-01

We report for the first time that Candida melibiosica expresses enhanced phytase activity when grown under biofuel cell polarization in a nutrient-poor medium, containing only fructose as a carbohydrate source. Phytase activity during the cultivation under polarization reached up to 25 U per g dry biomass, exceeding with 20 ± 3 % those of the control. A participation of the enzyme in the adaptation processes to the stress conditions is proposed. In addition, steady-state electrical outputs were achieved during biofuel cell operation at continuous polarization under constant load. The obtained results show that C. melibiosica yeast-based biofuel cell could be used for simultaneous electricity generation and phytate bioremediation.

Yeast: A Research Organism for Teaching Genetics.

ERIC Educational Resources Information Center

Manney, Thomas R.; Manney, Monta L.

1992-01-01

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

Selection of Yarrowia lipolytica strains with high protein content from yeasts isolated from different marine environments

NASA Astrophysics Data System (ADS)

Chi, Zhenming; Wang, Fang; Wang, Lin; Li, Jing; Wang, Xianghong

2007-10-01

A total of 78 Yarrowia lipolytica yeast strains from seawater, sediments, mud of salterns, the guts of marine fish, and marine algae were obtained. After the crude protein of the yeasts was estimated by the method of Kjehldahl, we found that seven strains of the marine yeasts grown in soy bean cake hydrolysate with 20 g L-1 of glucose for 48 h at 28°C contained more than 41.0 g protein per 100 g of cell dry weight and the cell dry weight was more than 4.4 g per L of the culture. Among them, strain SWJ-1b contained the highest crude protein. The results of Biolog identification and molecular methods further confirmed that they indeed belonged to Y. lipolytica.

Simulated in situ competitive ability and survival of a representative soil yeast, Cryptococcus albidus.

PubMed

Vishniac, H S

1995-11-01

Microcosms containing an air-dried autoclaved loamy sand (Eufala A) with low salt and organic content were inoculated with a representative (obligately aerobic, encapsulated) soil yeast, Cryptococcus albidus var. albidus (T) ATCC 10666, singly (for growth rate and survival determinations) and together with the bacterial biota native to Eufala A. The yeast competed successfully with the more rapidly growing bacteria in the presence of added water from 1% (5.7% of field capacity) to 14% (80% of field capacity) but grew for shorter times than when grown alone; times correlated with the lag phase of the bacterial biota. When well-watered (10 and 14%) competition cultures were allowed to dry and used as inoculum for subcultures, the yeast made significant growth only at 1% added water but survived at the higher moisture concentrations. The competitive ability of Cr. albidus confirms the previously reported advantages of the cryptococcal capsule in hydration and desiccation and, together with lengthy survival, suggests that the importance of such yeasts in the biogeochemistry of arid soils has been seriously underestimated.

Overexpression of the transcription activator Msn2 enhances the fermentation ability of industrial baker's yeast in frozen dough.

PubMed

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

2012-01-01

We constructed a self-cloning diploid baker's yeast strain that overexpressed the transcription activator Msn2. It showed higher tolerance to freeze-thaw stress and higher intracellular trehalose level than observed in the wild-type strain. Overexpression of Msn2 also enhanced the fermentation ability of baker's yeast cells in frozen dough. Hence, Msn2-overexpressing baker's yeast should be useful in frozen-dough baking.

Arrhenius activation energy of damage to catalase during spray-drying.

PubMed

Schaefer, Joachim; Lee, Geoffrey

2015-07-15

The inactivation of catalase during spray-drying over a range of outlet gas temperatures could be closely represented by the Arrhenius equation. From this an activation energy for damage to the catalase could be calculated. The close fit to Arrhenius suggests that the thermally-induced part of inactivation of the catalase during the complex drying and particle-formation processes takes place at constant temperature. These processes are rapid compared with the residence time of the powder in the collecting vessel of the cyclone where dried catalase is exposed to a constant temperature equal to approximately the drying gas outlet temperature. A lower activation energy after spray drying with the ultrasonic nozzle was found than with the 2-fluid nozzle under otherwise identical spray drying conditions. It is feasible that the ultrasonic nozzle when mounted in the lid of the spray dryer heats up toward the drying gas inlet temperature much more that the air-cooled 2-fluid nozzle. Calculation of the Arrhenius activation energy also showed how the stabilizing efficacy of trehalose and mannitol on the catalase varies in strength across the range of drying gas inlet and outlet temperatures examined. Copyright © 2015 Elsevier B.V. All rights reserved.

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

PubMed

DeVries, T J; Chevaux, E

2014-10-01

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

Glutathione depletion activates the yeast vacuolar transient receptor potential channel, Yvc1p, by reversible glutathionylation of specific cysteines

PubMed Central

Chandel, Avinash; Das, Krishna K.; Bachhawat, Anand K.

2016-01-01

Glutathione depletion and calcium influx into the cytoplasm are two hallmarks of apoptosis. We have been investigating how glutathione depletion leads to apoptosis in yeast. We show here that glutathione depletion in yeast leads to the activation of two cytoplasmically inward-facing channels: the plasma membrane, Cch1p, and the vacuolar calcium channel, Yvc1p. Deletion of these channels partially rescues cells from glutathione depletion–induced cell death. Subsequent investigations on the Yvc1p channel, a homologue of the mammalian TRP channels, revealed that the channel is activated by glutathionylation. Yvc1p has nine cysteine residues, of which eight are located in the cytoplasmic regions and one on the transmembrane domain. We show that three of these cysteines, Cys-17, Cys-79, and Cys-191, are specifically glutathionylated. Mutation of these cysteines to alanine leads to a loss in glutathionylation and a concomitant loss in calcium channel activity. We further investigated the mechanism of glutathionylation and demonstrate a role for the yeast glutathione S-transferase Gtt1p in glutathionylation. Yvc1p is also deglutathionylated, and this was found to be mediated by the yeast thioredoxin, Trx2p. A model for redox activation and deactivation of the yeast Yvc1p channel is presented. PMID:27708136

Technological properties of indigenous wine yeast strains isolated from wine production regions of Turkey.

PubMed

Bağder Elmacı, Simel; Özçelik, Filiz; Tokatlı, Mehmet; Çakır, İbrahim

2014-05-01

The purpose of this study was to evaluate the important technological and fermentative properties of wine yeast strains previously isolated from different wine producing regions of Turkey. The determination of the following important properties was made: growth at high temperatures; fermentative capability in the presence of high sugar concentration; fermentation rate; hydrogen sulfide production; killer activity; resistance to high ethanol and sulfur dioxide; foam production; and enzymatic profiles. Ten local wine yeast strains belonging to Saccharomyces, and one commercial active dry yeast as a reference strain were evaluated. Fermentation characteristics were evaluated in terms of kinetic parameters, including ethanol yield (YP/S), biomass yield (YX/S), theoretical ethanol yield (%), specific ethanol production rate (qp; g/gh), specific glucose uptake rate (qs; g/gh), and the substrate conversion (%). All tested strains were able to grow at 37 °C and to start fermentation at 30° Brix, and were resistant to high concentrations of sulfur dioxide. 60 % of the strains were weak H2S producers, while the others produced high levels. Foam production was high, and no strains had killer activity. Six of the tested strains had the ability to grow and ferment at concentrations of 14 % ethanol. Except for one strain, all fermented most of the media sugars at a high rate, producing 11.0-12.4 % (v/v) ethanol. Although all but one strain had suitable characteristics for wine production, they possessed poor activities of glycosidase, esterase and proteinase enzymes of oenological interest. Nine of the ten local yeast strains were selected for their good oenological properties and their suitability as a wine starter culture.

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

PubMed

Ganga, M A; Martínez, C

2004-01-01

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

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

PubMed

Niki, Hironori

2014-03-01

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

Characterization of commercial inactive dry yeast preparations for enological use based on their ability to release soluble compounds and their behavior toward aroma compounds in model wines.

PubMed

Pozo-Bayón, Maria Angeles; Andujar-Ortiz, Inmaculada; Alcaide-Hidalgo, Juan María; Martín-Alvarez, Pedro J; Moreno-Arribas, M Victoria

2009-11-25

The characterization of commercial enological inactive dry yeast (IDY) with different applications in wine production has been carried out. This study was based on the yeast's ability to release soluble compounds (high molecular weight nitrogen, free amino nitrogen, peptidic nitrogen, free amino acids, and polysaccharides) into model wines and on its behavior toward the volatility of seven wine aroma compounds. Important differences in soluble compounds released into the model wines supplemented with commercial IDY were found, with the free amino acids being among the most released. The volatility of most of the aroma compounds was affected by the addition of IDY preparations at a concentration usually employed during winemaking. The extent of this effect was dependent on the physicochemical characteristics of the aroma compound and on the length of time the IDY preparations remained in contact with the model wines. Whereas shorter contact times (2, 4, and 6 days) mainly promoted a "salting-out" effect, longer exposure (9 and 13 days) provoked a retention effect, with the consequent reduction of aroma compounds in the headspace. The use of different commercial preparations also promoted different effects toward the aroma compounds that may be at least in part due to differences in their ability to release soluble compounds of yeast origin into the wines.

The euryhaline yeast Debaryomyces hansenii has two catalase genes encoding enzymes with differential activity profile.

PubMed

Segal-Kischinevzky, Claudia; Rodarte-Murguía, Beatriz; Valdés-López, Victor; Mendoza-Hernández, Guillermo; González, Alicia; Alba-Lois, Luisa

2011-03-01

Debaryomyces hansenii is a spoilage yeast able to grow in a variety of ecological niches, from seawater to dairy products. Results presented in this article show that (i) D. hansenii has an inherent resistance to H2O2 which could be attributed to the fact that this yeast has a basal catalase activity which is several-fold higher than that observed in Saccharomyces cerevisiae under the same culture conditions, (ii) D. hansenii has two genes (DhCTA1 and DhCTT1) encoding two catalase isozymes with a differential enzymatic activity profile which is not strictly correlated with a differential expression profile of the encoding genes.

Effect of balanced low pressure drying of curcuma longa leaf on skin immune activation activities.

PubMed

Choi, Wooseok; Lim, Hye Won; Lee, Hyeon Yong

2014-01-01

The effect of balanced low pressure drying pretreatment associated with ultrasonication extraction (BU) on the enhancement of skin immune modulatory activities of Curcuma longa leaf was studied by comparing with conventional hot air drying (HE), freeze drying (FE) and balanced low pressure drying (BE) pretreatment processes. In considering skin immune activation activities such as the inhibition of hyaluronidase activity, the BU extract showed ca. 10% higher than those of HE, and even higher than that of the FE extract. Nitric oxide production from macrophage of the BU extract in adding 1.0 mg/mL was increased up to 16.5 μM. When measuring inhibition of IL-6 and TNF-a production from the human T lymphocytes (T cell), the BU extract also showed 53% and 78% of inhibition effect, respectively. It is found that the BU extract could effectively suppress the expression levels of skin inflammation related genes such as Cox-2 and iNOS, down to 80% and 85% compared to the control, respectively. Balanced low pressure drying process was especially active on dehydration of the leaves with minimizing the destruction and making easier elution of the bioactive substances, which resulted in higher extraction yield and better biological activities.

In vitro ability of beer fermentation residue and yeast-based products to bind aflatoxin B1.

PubMed

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

2015-06-01

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

In vitro ability of beer fermentation residue and yeast-based products to bind aflatoxin B1

PubMed Central

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

2015-01-01

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

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

PubMed

Palková, Zdena; Váchová, Libuše

2016-09-01

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

Effect of whey protein agglomeration on spray dried microcapsules containing Saccharomyces boulardii.

PubMed

Duongthingoc, Diep; George, Paul; Katopo, Lita; Gorczyca, Elizabeth; Kasapis, Stefan

2013-12-01

This work investigates the effect of whey protein agglomeration on the survivability of Saccharomyces boulardii within spray dried microcapsules. It attempts to go beyond phenomenological observations by establishing a relationship between physicochemical characteristics of the polymeric matrix and its effect on probiotic endurance upon spray drying. It is well known that this type of thermal shock has lethal consequences on the yeast cells. To avoid such undesirable outcome, we take advantage of the early agglomeration phenomenon observed for whey protein by adjusting the pH value of preparations close to isoelectric point (pH 4-5). During the subsequent process of spray drying, development of whey protein agglomerates induces formation of an early crust, and the protein in this molten globular state creates a cohesive network encapsulating the yeast cells. It appears that the early crust formation at a given sample pH and temperature regime during spray drying benefits the survivability of S. boulardii within microcapsules. Copyright © 2013. Published by Elsevier Ltd.

Effect of pulsed electric fields on the activity of neutral trehalase from beer yeast and RSM analysis.

PubMed

Ye, Haiqing; Jin, Yan; Lin, Songyi; Liu, Mingyuan; Yang, Yi; Zhang, Meishuo; Zhao, Ping; Jones, Gregory

2012-06-01

The trehalase activity plays an important role in extraction of trehalose from beer yeast. In this study, the effect of pulsed electric field processing on neutral trehalase activity in beer yeast was investigated. In order to develop and optimize a pulsed electric field (PEF) mathematical model for activating the neutral trehalase, we have investigated three variables, including electric field intensity (10-50 kV/cm), pulse duration (2-10 μs) and liquid-solid ratio (20-50 ml/g) and subsequently optimized them by response surface methodology (RSM). The experimental data were fitted to a second-order polynomial equation and profiled into the corresponding contour plots. Optimal condition obtained by RSM is as follows: electric field intensity 42.13 kV/cm, liquid-solid ratio 30.12 ml/g and pulse duration 5.46 μs. Under these conditions, with the trehalose decreased 8.879 mg/L, the PEF treatment had great effect on activating neutral trehalase in beer yeast cells. Copyright © 2012 Elsevier B.V. All rights reserved.

Estimating the effect of fermentation yeast on distillers grains protein

USDA-ARS?s Scientific Manuscript database

Distillers dried grains with solubles (DDGS) is the key co-product of bio-ethanol production from grains. Major factors affecting its quality and market values include protein quantity (concentration) and quality (amino acid composition). Yet, the effect of fermentation yeast on DDGS quality has no...

Interactions between Brettanomyces bruxellensis and other yeast species during the initial stages of winemaking.

PubMed

Renouf, V; Falcou, M; Miot-Sertier, C; Perello, M C; De Revel, G; Lonvaud-Funel, A

2006-06-01

Wine is the product of complex interactions between yeasts and bacteria in grape must. Amongst yeast populations, two groups can be distinguished. The first, named non-Saccharomyces (NS), colonizes, with many other micro-organisms, the surface of grape berries. In the past, NS yeasts were primarily considered as spoilage micro-organisms. However, recent studies have established a positive contribution of certain NS yeasts to wine quality. Amongst the group of NS yeasts, Brettanomyces bruxellensis, which is not prevalent on wine grapes, plays an important part in the evolution of wine aroma. Some of their secondary metabolites, namely volatile phenols, are responsible for wine spoilage. The other group contributing to wine aroma, which is also the main agent of alcoholic fermentation (AF), is composed of Saccharomyces species. The fermenting must is a complex microbial ecosystem where numerous yeast strains grow and die according to their adaptation to the medium. Yeast-yeast interactions occur during winemaking right from the onset of AF. The aim of this study was to describe the interactions between B. bruxellensis, other NS and Saccharomyces cerevisiae during laboratory and practical scale winemaking. Molecular methods such as internal transcribed spacer-restriction fragment length polymorphism and polymerase chain reaction and denaturing gradient gel electrophoresis were used in laboratory scale experiments and cellar observations. The influence of different oenological practices, like the level of sulphiting at harvest time, cold maceration preceding AF, addition of commercial active dry yeasts on B. bruxellensis and other yeast interactions and their evolution during the initial stages of winemaking have been studied. Brettanomyces bruxellensis was the most adapted NS yeast at the beginning of AF, and towards the end of AF it appeared to be more resistant than S. cerevisiae to the conditions of increased alcohol and sugar limitation. Among all NS yeast species

A new method for monitoring the extracellular proteolytic activity of wine yeasts during alcoholic fermentation of grape must.

PubMed

Chasseriaud, Laura; Miot-Sertier, Cécile; Coulon, Joana; Iturmendi, Nerea; Moine, Virginie; Albertin, Warren; Bely, Marina

2015-12-01

The existing methods for testing proteolytic activity are time consuming, quite difficult to perform, and do not allow real-time monitoring. Proteases have attracted considerable interest in winemaking and some yeast species naturally present in grape must, such as Metschnikowia pulcherrima, are capable of expressing this activity. In this study, a new test is proposed for measuring proteolytic activity directly in fermenting grape must, using azocasein, a chromogenic substrate. Several yeast strains were tested and differences in proteolytic activity were observed. Moreover, analysis of grape must proteins in wines revealed that protease secreted by Metschnikowia strains may be active against wine proteins. Copyright © 2015. Published by Elsevier B.V.

Evolution of cyclin-dependent kinases (CDKs) and CDK-activating kinases (CAKs): differential conservation of CAKs in yeast and metazoa.

PubMed

Liu, J; Kipreos, E T

2000-07-01

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

Purification and functional characterisation of the pyruvate (monocarboxylate) carrier from baker's yeast mitochondria (Saccharomyces cerevisiae).

PubMed

Nałecz, M J; Nałecz, K A; Azzi, A

1991-08-09

Isolated yeast mitochondria were subjected to solubilization by Triton X-114 and the detergent extract was subsequently chromatrographed on dry hydroxyapatite. Purification of the yeast monocarboxylate (pyruvate) carrier was achieved by affinity chromatography on immobilized 2-cyano-4-hydroxycinnamate, as described previously for bovine heart mitochondria (Bolli, R., Nałecz K.A. and Azzi, A. (1989) J. Biol. Chem. 264 18024-18030). The final preparation contained two polypeptides of apparent molecular mass 26 and 50 kDa. The yeast carrier appeared to be less abundant, but more active, than the analogous protein from higher eukaryotes. The carrier was able to catalyse the pyruvate / pyruvate and pyruvate / acetoacetate exchange reactions, both reactions being sensitive to cyanocinnamate and its derivatives, to phenylpyruvate and to mersalyl and p-chloromercuribenzoate. In the pyruvate / acetoacetate exchange reaction (200 mM internal acetoacetate, enzymatic assay), the Km value for external pyruvate was found to be 0.8 mM and the Vmax 135 mumol/min per mg protein. Among other substrates of the yeast carrier, all transported with similar affinity and identical maximal velocity against acetoacetate, we identified 2-oxoisocaproate, 2-oxoisovalerate and 2-oxo-3-methylvalerate. Lactate was not translocated by this carrier with a measurable rate, neither were di- or tricarboxylates.

Genomic and Phenotypic Characterization of Yeast Biosensor for Deep-space Radiation

NASA Technical Reports Server (NTRS)

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

2016-01-01

The BioSentinel mission was selected to launch as a secondary payload onboard NASA Exploration Mission 1 (EM-1) in 2018. In BioSentinel, the budding yeast Saccharomyces cerevisiae will be used as a biosensor to measure the long-term impact of deep-space radiation to living organisms. In the 4U-payload, desiccated yeast cells from different strains will be stored inside microfluidic cards equipped with 3-color LED optical detection system to monitor cell growth and metabolic activity. At different times throughout the 12-month mission, these cards will be filled with liquid yeast growth media to rehydrate and grow the desiccated cells. The growth and metabolic rates of wild-type and radiation-sensitive strains in deep-space radiation environment will be compared to the rates measured in the ground- and microgravity-control units. These rates will also be correlated with measurements obtained from onboard physical dosimeters. In our preliminary long-term desiccation study, we found that air-drying yeast cells in 10% trehalose is the best method of cell preservation in order to survive the entire 18-month mission duration (6-month pre-launch plus 12-month full-mission periods). However, our study also revealed that desiccated yeast cells have decreasing viability over time when stored in payload-like environment. This suggests that the yeast biosensor will have different population of cells at different time points during the long-term mission. In this study, we are characterizing genomic and phenotypic changes in our yeast biosensor due to long-term storage and desiccation. For each yeast strain that will be part of the biosensor, several clones were reisolated after long-term storage by desiccation. These clones were compared to their respective original isolate in terms of genomic composition, desiccation tolerance and radiation sensitivity. Interestingly, clones from a radiation-sensitive mutant have better desiccation tolerance compared to their original isolate

Tolerance of budding yeast Saccharomyces cerevisiae to ultra high pressure

NASA Astrophysics Data System (ADS)

Ono, Fumihisa; Shibata, Michiko; Torigoe, Motoki; Matsumoto, Yuta; Yamamoto, Shinsuke; Takizawa, Noboru; Hada, Yoshio; Mori, Yoshihisa; Takarabe, Kenichi

2013-06-01

In our previous studies on the tolerance of small plants and animals to the high hydrostatic pressure of 7.5 GPa, it was shown that all the living samples could be borne at this high pressure, which is more than one order of magnitude higher than the proteinic denaturation pressure. To make this inconsistency clear, we have extended these studies to a smaller sized fungus, budding yeast Saccharomyces cerevisiae. A several pieces of budding yeast (dry yeast) were sealed in a small teflon capsule with a liquid pressure medium fluorinate (PC72, Sumitomo 3M), and exposed to 7.5 GPa by using a cubic anvil press. The pressure was kept constant for various duration of time from 2 to 24 h. After the pressure was released, the specimens were brought out from the teflon capsule, and they were cultivated on a potato dextrose agar (PDA). It was found that the budding yeast exposed to 7.5 GPa for up to 6 h showed multiplication. However, those exposed to 7.5 GPa for 12 and 24 h were found dead. The high pressure tolerance of budding yeast is weaker than that of tardigrades.

MET18 Deficiency Increases the Sensitivity of Yeast to Oxidative Stress and Shortens Replicative Lifespan by Inhibiting Catalase Activity.

PubMed

Chen, Ya-Qin; Liu, Xin-Guang; Zhao, Wei; Cui, Hongjing; Ruan, Jie; Yuan, Yuan; Tu, Zhiguang

2017-01-01

Yeast MET18 , a subunit of the cytosolic iron-sulfur (Fe/S) protein assembly (CIA) machinery which is responsible for the maturation of Fe/S proteins, has been reported to participate in the oxidative stress response. However, the underlying molecular mechanisms remain unclear. In this study, we constructed a MET18/met18Δ heterozygous mutant yeast strain and found that MET18 deficiency in yeast cells impaired oxidative stress resistance as evidenced by increased sensitivity to hydrogen peroxide (H 2 O 2 ) and cumene hydroperoxide (CHP). Mechanistically, the mRNA levels of catalase A (CTA1) and catalase T (CTT1) as well as the total catalase activity were significantly reduced in MET18 -deficient cells. In contrast, overexpression of CTT1 or CTA1 in MET18 -deficient cells significantly increased the intracellular catalase activity and enhanced the resistance ability against H 2 O 2 and CHP. In addition, MET18 deficiency diminished the replicative capacity of yeast cells as evidenced by the shortened replicative lifespan, which can be restored by CTT1 overexpression, but not by CTA1 , in the MET18 -deficient cells. These results suggest that MET18 , in a catalase-dependent manner, plays an essential role in enhancing the resistance of yeast cells to oxidative stress and increasing the replicative capacity of yeast cells.

MET18 Deficiency Increases the Sensitivity of Yeast to Oxidative Stress and Shortens Replicative Lifespan by Inhibiting Catalase Activity

PubMed Central

Zhao, Wei; Cui, Hongjing

2017-01-01

Yeast MET18, a subunit of the cytosolic iron-sulfur (Fe/S) protein assembly (CIA) machinery which is responsible for the maturation of Fe/S proteins, has been reported to participate in the oxidative stress response. However, the underlying molecular mechanisms remain unclear. In this study, we constructed a MET18/met18Δ heterozygous mutant yeast strain and found that MET18 deficiency in yeast cells impaired oxidative stress resistance as evidenced by increased sensitivity to hydrogen peroxide (H2O2) and cumene hydroperoxide (CHP). Mechanistically, the mRNA levels of catalase A (CTA1) and catalase T (CTT1) as well as the total catalase activity were significantly reduced in MET18-deficient cells. In contrast, overexpression of CTT1 or CTA1 in MET18-deficient cells significantly increased the intracellular catalase activity and enhanced the resistance ability against H2O2 and CHP. In addition, MET18 deficiency diminished the replicative capacity of yeast cells as evidenced by the shortened replicative lifespan, which can be restored by CTT1 overexpression, but not by CTA1, in the MET18-deficient cells. These results suggest that MET18, in a catalase-dependent manner, plays an essential role in enhancing the resistance of yeast cells to oxidative stress and increasing the replicative capacity of yeast cells. PMID:28828388

Influence of yeast macromolecules on sweetness in dry wines: role of the saccharomyces cerevisiae protein Hsp12.

PubMed

Marchal, Axel; Marullo, Philippe; Moine, Virginie; Dubourdieu, Denis

2011-03-09

Yeast autolysis during lees contact influences the organoleptic properties of wines especially by increasing their sweet taste. Although observed by winemakers, this phenomenon is poorly explained in enology. Moreover, the compounds responsible for sweetness in wine remain unidentified. This work provides new insights in this way by combining sensorial, biochemical and genetic approaches. First, we verified by sensory analysis that yeast autolysis in red wine has a significant effect on sweetness. Moderate additions of ethanol or glycerol did not have the same effect. Second, a sapid fraction was isolated from lees extracts by successive ultrafiltrations and HPLC purifications. Using nano-LC-MS/MS, peptides released by the yeast heat shock protein Hsp12p were distinctly identified in this sample. Third, we confirmed the sweet contribution of this protein by sensorial comparison of red wines incubated with two kinds of yeast strains: a wild-type strain containing the native Hsp12p and a deletion mutant strain that lacks the Hsp12p protein (Δ°HSP12 strain). Red wines incubated with wild-type strain showed a significantly higher sweetness than control wines incubated with Δ°HSP12 strains. These results demonstrated the contribution of protein Hsp12p in the sweet perception consecutive to yeast autolysis in wine.

The SUD1 gene encodes a putative E3 ubiquitin ligase and is a positive regulator of 3-hydroxy-3-methylglutaryl coenzyme a reductase activity in Arabidopsis.

PubMed

Doblas, Verónica G; Amorim-Silva, Vítor; Posé, David; Rosado, Abel; Esteban, Alicia; Arró, Montserrat; Azevedo, Herlander; Bombarely, Aureliano; Borsani, Omar; Valpuesta, Victoriano; Ferrer, Albert; Tavares, Rui M; Botella, Miguel A

2013-02-01

The 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) enzyme catalyzes the major rate-limiting step of the mevalonic acid (MVA) pathway from which sterols and other isoprenoids are synthesized. In contrast with our extensive knowledge of the regulation of HMGR in yeast and animals, little is known about this process in plants. To identify regulatory components of the MVA pathway in plants, we performed a genetic screen for second-site suppressor mutations of the Arabidopsis thaliana highly drought-sensitive drought hypersensitive2 (dry2) mutant that shows decreased squalene epoxidase activity. We show that mutations in SUPPRESSOR OF DRY2 DEFECTS1 (SUD1) gene recover most developmental defects in dry2 through changes in HMGR activity. SUD1 encodes a putative E3 ubiquitin ligase that shows sequence and structural similarity to yeast Degradation of α factor (Doα10) and human TEB4, components of the endoplasmic reticulum-associated degradation C (ERAD-C) pathway. While in yeast and animals, the alternative ERAD-L/ERAD-M pathway regulates HMGR activity by controlling protein stability, SUD1 regulates HMGR activity without apparent changes in protein content. These results highlight similarities, as well as important mechanistic differences, among the components involved in HMGR regulation in plants, yeast, and animals.

Effect of Increased Yeast Alcohol Acetyltransferase Activity on Flavor Profiles of Wine and Distillates

PubMed Central

Lilly, M.; Lambrechts, M. G.; Pretorius, I. S.

2000-01-01

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

Nutrient depletion modifies cell wall adsorption activity of wine yeast.

PubMed

Sidari, R; Caridi, A

2016-06-01

Yeast cell wall is a structure that helps yeasts to manage and respond to many environmental stresses. The mannosylphosphorylation is a modification in response to stress that provides the cell wall with negative charges able to bind compounds present in the environment. Phenotypes related to the cell wall modification such as the filamentous growth in Saccharomyces cerevisiae are affected by nutrient depletion. The present work aimed at describing the effect of carbon and/or nitrogen limitation on the aptitude of S. cerevisiae strains to bind coloured polyphenols. Carbon- and nitrogen-rich or deficient media supplemented with grape polyphenols were used to simulate different grape juice conditions-early, mid, 'adjusted' for nitrogen, and late fermentations. In early fermentation condition, the R+G+B values range from 106 (high adsorption, strain Sc1128) to 192 (low adsorption, strain Σ1278b), in mid-fermentation the values range from 111 (high adsorption, strain Sc1321) to 258 (low adsorption, strain Sc2306), in 'adjusted' for nitrogen conditions the values range from 105 (high adsorption, strain Sc1321) to 194 (low adsorption, strain Sc2306) while in late fermentation conditions the values range from 101 (high adsorption, strain Sc384) to 293 (low adsorption, strain Sc2306). The effect of nutrient availability is not univocal for all the strains and the different media tested modified the strains behaviour. In all the media the strains show significant differences. Results demonstrate that wine yeasts decrease/increase their parietal adsorption activity according to the nutrient availability. The wide range of strain variability observed could be useful in selecting wine starters.

Survival of commercial yeasts in the winery environment and their prevalence during spontaneous fermentations.

PubMed

Blanco, P; Orriols, I; Losada, A

2011-01-01

Inoculation of active dry yeasts during the wine-making process has become a common practice in most wine-producing regions; this practice may affect the diversity of the indigenous population of Saccharomyces cerevisiae in the winery. The aim of this work was to study the incidence of commercial yeasts in the experimental winery of Estación de Viticultura e Enoloxía de Galicia (EVEGA) and their ability to lead spontaneous fermentations. To do this, 64 spontaneous fermentations were carried out in the experimental cellar of EVEGA over a period of 7 years. Samples were taken from must and at the beginning, vigorous and final stages of fermentation. A representative number of yeast colonies was isolated from each sample. S. cerevisiae strains were characterised by analysis of mitochondrial DNA restriction patterns. The results showed that although more than 40 different strains of S. cerevisiae were identified, only 10 were found as the dominant strain or in codominance with other strains in spontaneous fermentations. The genetic profiles (mtDNA-RFLPs) of eight of these strains were similar to those of different commercial yeasts that had been previously used in the EVEGA cellar. The remaining two strains were autochthonous ones that were able to reach implantation frequencies as high of those of commercial yeasts. These results clearly indicated that commercial wine yeasts were perfectly adapted to survive in EVEGA cellar conditions, and they successfully competed with the indigenous strains of S. cerevisiae, even during spontaneous fermentations. On the other hand, autochthonous dominant strains that presented desirable oenological traits could be of interest to preserve wine typicity.

Biocontrol activity of a cold-adapted yeast from Tibet against gray mold in cherry tomato and its action mechanism.

PubMed

Hu, Hao; Wisniewski, Michael E; Abdelfattah, Ahmed; Zheng, Xiaodong

2017-07-01

Cold-adapted biocontrol yeast was selected from four yeast isolates from Tibet against gray mold of cherry tomato in cold storage. The strain numbered LB2 showed the best biocontrol activity and identified as Cryptococcus laurentii. Competition for nutrient, space, and induced fruit resistance was also its antagonistic mechanism. Compared with C. laurentii from sea-level place, the reason why LB2 had a better biocontrol activity was studied. More trehalose and proline in cell of LB2 made it exhibit a better cellular activity at low temperature, such as higher population dynamics in the wounds of cherry tomato and more biocontrol-related enzyme secretion, chitinase and β-glucanase. The better oxidative stress tolerance was another characteristic of LB2. Maybe because of the ideal culture condition, there was no obvious difference between these two yeasts in the growth in vitro test at low temperature. Although the same phenomenon existed in the low pH stress test, LB2 still had higher cell concentration under this stress. Comparative transcriptomics method was also applied to analyze the cell activity of LB2 and C. laurentii at different temperatures. The results showed that more active response in the intracellular structure and intracellular metabolic process to cold temperature made LB2 had a better activity. The present study indicated a possibility to select cold-adapted biocontrol yeast from Tibet and also showed its primary action mechanism.

Lignocellulosic ethanol production by starch-base industrial yeast under PEG detoxification

PubMed Central

Liu, Xiumei; Xu, Wenjuan; Mao, Liaoyuan; Zhang, Chao; Yan, Peifang; Xu, Zhanwei; Zhang, Z. Conrad

2016-01-01

Cellulosic ethanol production from lignocellulosic biomass offers a sustainable solution for transition from fossil based fuels to renewable alternatives. However, a few long-standing technical challenges remain to be addressed in the development of an economically viable fermentation process from lignocellulose. Such challenges include the needs to improve yeast tolerance to toxic inhibitory compounds and to achieve high fermentation efficiency with minimum detoxification steps after a simple biomass pretreatment. Here we report an in-situ detoxification strategy by PEG exo-protection of an industrial dry yeast (starch-base). The exo-protected yeast cells displayed remarkably boosted vitality with high tolerance to toxic inhibitory compounds, and with largely improved ethanol productivity from crude hydrolysate derived from a pretreated lignocellulose. The PEG chemical exo-protection makes the industrial S. cerevisiae yeast directly applicable for the production of cellulosic ethanol with substantially improved productivity and yield, without of the need to use genetically modified microorganisms. PMID:26837707

Lignocellulosic ethanol production by starch-base industrial yeast under PEG detoxification

NASA Astrophysics Data System (ADS)

Liu, Xiumei; Xu, Wenjuan; Mao, Liaoyuan; Zhang, Chao; Yan, Peifang; Xu, Zhanwei; Zhang, Z. Conrad

2016-02-01

Cellulosic ethanol production from lignocellulosic biomass offers a sustainable solution for transition from fossil based fuels to renewable alternatives. However, a few long-standing technical challenges remain to be addressed in the development of an economically viable fermentation process from lignocellulose. Such challenges include the needs to improve yeast tolerance to toxic inhibitory compounds and to achieve high fermentation efficiency with minimum detoxification steps after a simple biomass pretreatment. Here we report an in-situ detoxification strategy by PEG exo-protection of an industrial dry yeast (starch-base). The exo-protected yeast cells displayed remarkably boosted vitality with high tolerance to toxic inhibitory compounds, and with largely improved ethanol productivity from crude hydrolysate derived from a pretreated lignocellulose. The PEG chemical exo-protection makes the industrial S. cerevisiae yeast directly applicable for the production of cellulosic ethanol with substantially improved productivity and yield, without of the need to use genetically modified microorganisms.

[Thermoresistance in Saccharomyces cerevisiae yeasts].

PubMed

Kaliuzhin, V A

2011-01-01

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

Interaction Between Yeasts and Zinc

NASA Astrophysics Data System (ADS)

Nicola, Raffaele De; Walker, Graeme

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

Fuel ethanol from raw corn by Aspergilli hydrolysis with concurrent yeast fermentation

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

Weller, C.L.; Steinberg, M.P.; Rodda, E.D.

Crude amylase preparations were produced by growing Aspergillus awamori and A. niger on raw ground whole corn. These Koji preparations were used to hydrolyze the starch of raw ground whole corn to sugars during simultaneous fermentation of the sugars to ethanol by distillers active dry yeast. Ethanol concentrations of the fermentation beers were determined with gas chromatography. These fermentations yielded an average of 89.6% theoretical ethanol compared to control, conventional, fermentations that had an average of 89.9%. Carbon dioxide evolutions were determined with use of Alwood valves. Both the Koji and conventional fermentations produced an average of 0.48 g ofmore » carbon dioxide per gram of dry substrate starch within 72 h. However, initially the conventional fermentation rate was greater. Koji dehydrated at 41/sup 0/C had no apparent detrimental effects on theoretical ethanol yield. 41 references, 1 figure, 2 tables.« less

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

PubMed

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.

Designing CAF-adjuvanted dry powder vaccines: spray drying preserves the adjuvant activity of CAF01.

PubMed

Ingvarsson, Pall Thor; Schmidt, Signe Tandrup; Christensen, Dennis; Larsen, Niels Bent; Hinrichs, Wouter Leonardus Joseph; Andersen, Peter; Rantanen, Jukka; Nielsen, Hanne Mørck; Yang, Mingshi; Foged, Camilla

2013-05-10

Dry powder vaccine formulations are highly attractive due to improved storage stability and the possibility for particle engineering, as compared to liquid formulations. However, a prerequisite for formulating vaccines into dry formulations is that their physicochemical and adjuvant properties remain unchanged upon rehydration. Thus, we have identified and optimized the parameters of importance for the design of a spray dried powder formulation of the cationic liposomal adjuvant formulation 01 (CAF01) composed of dimethyldioctadecylammonium (DDA) bromide and trehalose 6,6'-dibehenate (TDB) via spray drying. The optimal excipient to stabilize CAF01 during spray drying and for the design of nanocomposite microparticles was identified among mannitol, lactose and trehalose. Trehalose and lactose were promising stabilizers with respect to preserving liposome size, as compared to mannitol. Trehalose and lactose were in the glassy state upon co-spray drying with the liposomes, whereas mannitol appeared crystalline, suggesting that the ability of the stabilizer to form a glassy matrix around the liposomes is one of the prerequisites for stabilization. Systematic studies on the effect of process parameters suggested that a fast drying rate is essential to avoid phase separation and lipid accumulation at the surface of the microparticles during spray drying. Finally, immunization studies in mice with CAF01 in combination with the tuberculosis antigen Ag85B-ESAT6-Rv2660c (H56) demonstrated that spray drying of CAF01 with trehalose under optimal processing conditions resulted in the preservation of the adjuvant activity in vivo. These data demonstrate the importance of liposome stabilization via optimization of formulation and processing conditions in the engineering of dry powder liposome formulations. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of Microwave Vacuum Drying on the Drying Characteristics, Color, Microstructure, and Antioxidant Activity of Green Coffee Beans.

PubMed

Dong, Wenjiang; Cheng, Ke; Hu, Rongsuo; Chu, Zhong; Zhao, Jianping; Long, Yuzhou

2018-05-11

The aim of this study is to investigate the effect of microwave vacuum drying (MVD) on the drying characteristics and quality attributes of green coffee beans. We specifically focused on the effective moisture diffusion coefficient ( D eff ), surface temperature, glass transition temperature ( T g ), water state, and microstructure. The kinetics of color changes during drying, total phenolic content (TPC), and antioxidant activity (DPPH, FRAP, and ABTS) were also characterized. Microwave power during MVD affected the porosity of coffee beans, their color, TPC, and antioxidant activity. The Allometric 1 model was the most suitable for simulating surface temperature rise kinetics. Thermal processing of green coffee beans resulted in increased b* , L* , Δ E , and TPC values, and greater antioxidant capacity. These findings may provide a theoretical reference for the technical improvement, mechanisms of flavor compound formation, and quality control of dried green coffee beans.

“In vitro” antifungal activity of ozonized sunflower oil on yeasts from onychomycosis

PubMed Central

Guerrer, L.V.; Cunha, K. C.; Nogueira, M. C. L.; Cardoso, C. C.; Soares, M. M. C. N.; Almeida, M. T. G.

2012-01-01

The “in vitro” antifungal activity of ozonized sunflower oil (Bioperoxoil®) was tested on 101 samples of yeasts originating from onychomycosis using the disk diffusion method. The oil was efficacious against several clinical fungal strains: Candida parapsilosis, Candida albicans, Trichosporon asahii, Candida tropicalis and Candida guilliermondii. PMID:24031958

Evaluation of Automated Yeast Identification System

NASA Technical Reports Server (NTRS)

McGinnis, M. R.

1996-01-01

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

The SUD1 Gene Encodes a Putative E3 Ubiquitin Ligase and Is a Positive Regulator of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Activity in Arabidopsis[C][W

PubMed Central

Doblas, Verónica G.; Amorim-Silva, Vítor; Posé, David; Rosado, Abel; Esteban, Alicia; Arró, Montserrat; Azevedo, Herlander; Bombarely, Aureliano; Borsani, Omar; Valpuesta, Victoriano; Ferrer, Albert; Tavares, Rui M.; Botella, Miguel A.

2013-01-01

The 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) enzyme catalyzes the major rate-limiting step of the mevalonic acid (MVA) pathway from which sterols and other isoprenoids are synthesized. In contrast with our extensive knowledge of the regulation of HMGR in yeast and animals, little is known about this process in plants. To identify regulatory components of the MVA pathway in plants, we performed a genetic screen for second-site suppressor mutations of the Arabidopsis thaliana highly drought-sensitive drought hypersensitive2 (dry2) mutant that shows decreased squalene epoxidase activity. We show that mutations in SUPPRESSOR OF DRY2 DEFECTS1 (SUD1) gene recover most developmental defects in dry2 through changes in HMGR activity. SUD1 encodes a putative E3 ubiquitin ligase that shows sequence and structural similarity to yeast Degradation of α factor (Doα10) and human TEB4, components of the endoplasmic reticulum–associated degradation C (ERAD-C) pathway. While in yeast and animals, the alternative ERAD-L/ERAD-M pathway regulates HMGR activity by controlling protein stability, SUD1 regulates HMGR activity without apparent changes in protein content. These results highlight similarities, as well as important mechanistic differences, among the components involved in HMGR regulation in plants, yeast, and animals. PMID:23404890

Yeasts as important agents of onychomycosis: in vitro activity of propolis against yeasts isolated from patients with nail infection.

PubMed

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

2013-01-01

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

The yeast actin cytoskeleton.

PubMed

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

2014-03-01

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

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

PubMed

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

2012-12-01

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

Nonlinear Dielectric Properties of Yeast Cells Cultured in Different Environmental Conditions

NASA Astrophysics Data System (ADS)

Kawanishi, Gomon; Fukuda, Naoki; Muraji, Masafumi

The harmonics of the electric current through yeast suspensions, the nonlinear dielectric properties of yeast cells, have particular patterns according to the biological activity of the cells and the measurement of these patterns is a technique for determining the activity of living cells. The concentration of glucose and oxygen in yeast culture medium influences the manifestation of fermentation or respiration of yeast cells. Measurements were made with yeast cells (Saccharomyces cerevisiae) cultured aerobically and anaerobically in sufficient glucose concentration, aerobic fermentation and anaerobic fermentation, and aerobically in limited glucose concentration, respiration. The results showed that the harmonics were barely apparent for yeast cells in aerobic fermentation and respiratory; however, cells in the anaerobic fermentation displayed substantial third and fifth harmonics. We can say that environmental condition affects the yeast cells' nonlinear properties, from another viewpoint, the measurements of the nonlinear properties are available to determine the activity of yeast cells adjusted to the conditions of their cultivation.

Effect of microwave drying and oven drying on the water activity, color, phenolic compounds content and antioxidant activity of coconut husk (Cocos nucifera L.).

PubMed

Valadez-Carmona, Lourdes; Cortez-García, Rosa María; Plazola-Jacinto, Carla Patricia; Necoechea-Mondragón, Hugo; Ortiz-Moreno, Alicia

2016-09-01

The coconut ( Cocos nucifera L.) husk is basically composed by fiber and pith material and remained under-utilized. This is an important source of phenolic compounds that could be used as functional ingredients. The aim of this study was to determine the effect of: oven-drying (OD) and microwave drying (MD), on the water activity, color, phenolic compound content and antioxidant activity of coconut husk. The OD was performed at 60 °C for 12 h and MD was performed at 900 W for 10 min. The total phenolic content (TPC) in fresh coconut husk was 64.2 mg GAE/g dry wt and significant higher than observed after OD and MD of 35.8 and 45.5 mg GAE/g dry wt, respectively. Ten phenols were identified in fresh and dehydrated coconut husks. The husk MD showed an increase in the content of gallic, 4-hydroxybenzoic, ferulic and syringic acids and epicatechin compared with the fresh; while coconut husk OD and MD, showed a decrease in the content of vanillic acid, vanillin, catequin and kaempferol. The antioxidant activity decreased after both OD and MD. However, MD resulted in a better antioxidant activity in husk than OD. MD of husk resulted into better retention of preserved color, TPC and TFC than OD.

Isolation, selection and evaluation of yeasts for use in fermentation of coffee beans by the wet process.

PubMed

de Melo Pereira, Gilberto Vinícius; Soccol, Vanete Thomaz; Pandey, Ashok; Medeiros, Adriane Bianchi Pedroni; Andrade Lara, João Marcos Rodrigues; Gollo, André Luiz; Soccol, Carlos Ricardo

2014-10-01

During wet processing of coffee, the ripe cherries are pulped, then fermented and dried. This study reports an experimental approach for target identification and selection of indigenous coffee yeasts and their potential use as starter cultures during the fermentation step of wet processing. A total of 144 yeast isolates originating from spontaneously fermenting coffee beans were identified by molecular approaches and screened for their capacity to grow under coffee-associated stress conditions. According to ITS-rRNA gene sequencing, Pichia fermentans and Pichia kluyveri were the most frequent isolates, followed by Candida Candida glabrata, quercitrusa, Saccharomyces sp., Pichia guilliermondii, Pichia caribbica and Hanseniaspora opuntiae. Nine stress-tolerant yeast strains were evaluated for their ability to produce aromatic compounds in a coffee pulp simulation medium and for their pectinolytic activity. P. fermentans YC5.2 produced the highest concentrations of flavor-active ester compounds (viz., ethyl acetate and isoamyl acetate), while Saccharomyces sp. YC9.15 was the best pectinase-producing strain. The potential impact of these selected yeast strains to promote flavor development in coffee beverages was investigated for inoculating coffee beans during wet fermentation trials at laboratory scale. Inoculation of a single culture of P. fermentans YC5.2 and co-culture of P. fermentans YC5.2 and Saccharomyces sp. YC9.15 enhanced significantly the formation of volatile aroma compounds during the fermentation process compared to un-inoculated control. The sensory analysis indicated that the flavor of coffee beverages was influenced by the starter cultures, being rated as having the higher sensory scores for fruity, buttery and fermented aroma. This demonstrates a complementary role of yeasts associated with coffee quality through the synthesis of yeast-specific volatile constituents. The yeast strains P. fermentans YC5.2 and Saccharomyces sp. YC9.15 have a great

Engineering prokaryotic transcriptional activators as metabolite biosensors in yeast.

PubMed

Skjoedt, Mette L; Snoek, Tim; Kildegaard, Kanchana R; Arsovska, Dushica; Eichenberger, Michael; Goedecke, Tobias J; Rajkumar, Arun S; Zhang, Jie; Kristensen, Mette; Lehka, Beata J; Siedler, Solvej; Borodina, Irina; Jensen, Michael K; Keasling, Jay D

2016-11-01

Whole-cell biocatalysts have proven a tractable path toward sustainable production of bulk and fine chemicals. Yet the screening of libraries of cellular designs to identify best-performing biocatalysts is most often a low-throughput endeavor. For this reason, the development of biosensors enabling real-time monitoring of production has attracted attention. Here we applied systematic engineering of multiple parameters to search for a general biosensor design in the budding yeast Saccharomyces cerevisiae based on small-molecule binding transcriptional activators from the prokaryote superfamily of LysR-type transcriptional regulators (LTTRs). We identified a design supporting LTTR-dependent activation of reporter gene expression in the presence of cognate small-molecule inducers. As proof of principle, we applied the biosensors for in vivo screening of cells producing naringenin or cis,cis-muconic acid at different levels, and found that reporter gene output correlated with production. The transplantation of prokaryotic transcriptional activators into the eukaryotic chassis illustrates the potential of a hitherto untapped biosensor resource useful for biotechnological applications.

Antifungal Activity of Diglycerin Ester of Fatty Acids against Yeasts and Its Comparison with Those of Sucrose Monopalmitate and Sodium Benzoate.

PubMed

Shimazaki, Aiko; Sakamoto, Jin J; Furuta, Masakazu; Tsuchido, Tetsuaki

2016-01-01

The antifungal activities of diglycerin monoester of fatty acids (DGCs), which have been employed as food emulsifiers, were examined against three yeasts, Saccharomyces cerevisiae, Candida albicans and Candida utilis and were compared with those of sucrose monoester of palmitic acid (SC16) as another type of emulsifier and sodium benzoate (SB) as a weak acid food preservative. When the minimum growth inhibitory concentrations (MICs) of diglycerin monolaurate (DGC12) against these yeasts were determined 2 d after incubation in YM broth at pH5.0, they were relatively low, being 0.01% (w/v), for both S. cerevisiae and C. utilis, whereas was high, being 4.0% (w/v), for C. albicans. On the contrary, the MICs of sucrose monopalmitate (SC16) were high, being 3.0 and 4.0% (w/v), for the former two yeasts, respectively, but 0.6% (w/v) for the last yeast. In contrast to these emulsifiers, the MICs of sodium benzoate (SB) were similar independently upon the yeast strain, being in order 0.4, 0.3 and 0.5% (w/v), for the above yeasts, respectively. The anti-yeast activities of DGC12 and SC16 were gradually increased with a decrease in pH, in a manner similar to that of SB, except for the action of SC16 on C. albicans, for which the activity was more effective at pHs 5.0 and 6.0 than at pHs 4.0 and 7.0. Among DGCs tested having different fatty acid moieties in the molecule, lauroyl ester (DGC12) was more effective than myristoyl and palmitoyl esters against S. cerevisiae and C. utilis. The inhibitory effect of DGC12 on the yeast growth depended upon both the cell density and the strength of aeration during the treatment. Further, DGC12 was found to kill S. cerevisiae and C. utilis cells at a rather low concentration of 0.005% (w/v) in 50mM acetate buffer at pH5.0, although, against C. albicans cells, only slight fungicidal activity was demonstrated at a high concentration of 0.5% (w/v). The results obtained support the effectiveness of practical application of DGC12 to acidic

Fisetin yeast-based bio-capsules via osmoporation: effects of process variables on the encapsulation efficiency and internalized fisetin content.

PubMed

de Câmara, Antonio Anchieta; Dupont, Sébastien; Beney, Laurent; Gervais, Patrick; Rosenthal, Amauri; Correia, Roberta Targino Pinto; Pedrini, Márcia Regina da Silva

2016-06-01

Osmoporation is an innovative method that can be used with food-grade yeast cells of Saccharomyces cerevisiae as natural encapsulating matrices. This technique overcomes barriers that difficult encapsulation and enables the internalization of fragile bioactive molecules such as fisetin into yeasts. In the present study, we assessed the effects of concentration, osmotic pressure, and temperature on the encapsulation efficiency (EE) and internalized fisetin content (IF). Two different quantification strategies were investigated: direct extraction (DE) without cell washing or freeze-drying steps and indirect extraction (IE) performed after washings with ethanol and freeze-drying. Our results showed that osmoporation improved EE (33 %) and IF (1.199 mg). The best experimental conditions were found by using DE. High-resolution images showed that the yeast cell envelope was preserved during osmoporation at 30 MPa and 84 % of yeast cells remained viable after treatment. Washing cells with organic solvent led to decreased EE (0.65 %) and IF (0.023 mg). This was probably due to either damages caused to yeast cell envelope or fisetin dragged out of cell. Overall, the results demonstrated the adequacy and relevant biotechnological potential of yeasts as encapsulating matrices for hydrophobic compounds. This fresh biotechnological approach has proven to be a promising tool for the production of bioactive-rich food products.

Proteomic evolution of a wine yeast during the first hours of fermentation.

PubMed

Salvadó, Zoel; Chiva, Rosana; Rodríguez-Vargas, Sonia; Rández-Gil, Francisca; Mas, Albert; Guillamón, José Manuel

2008-11-01

The inoculation of active dry wine yeast (ADWY) is one of the most common practices in winemaking. This inoculation exposes the yeast cells to strong osmotic, acidic and thermal stresses, and adaptation to the new medium is crucial for successful fermentation. We have analysed the changes that occur in the ADWY protein profile in the first hours after inoculation under enological-like conditions at a low temperature. Protein changes mainly included enzymes of the nitrogen and carbon metabolism and proteins related to the cellular stress response. Most of the enzymes of the lower part of the glycolysis showed an increase in their concentration 4 and 24 h after inoculation, indicating an increase in glycolytic flux and in ATP production. However, the shift from respiration to fermentation was not immediate in the inoculation because some mitochondrial proteins involved in oxidative metabolism were induced in the first hours after inoculation. Inoculation in this fresh medium also reduced the cellular concentration of stress proteins produced during industrial production of the ADWY. The only exception was Cys3p, which might be involved in glutathione synthesis as a response to oxidative stress. A better understanding of the yeast stress response to rehydration and inoculation will lead to improvements in the handling efficiency of ADWY in winemaking and presumably to better control of fermentation startup.

The effect of yeast weight and temperature on ethanol production from sorghum and iles-iles flour

NASA Astrophysics Data System (ADS)

Kusmiyati, Shitophyta, Lukhi Mulia

2015-12-01

An increased of human need that spend a lot of energy, especially fuel resulting in excessive energy consumption. Therefore, the existence of alternative energy that renewable and environmentally friendly, such as bioethanol is required. In this study the use of sorghum and iles-iles as raw materials for bioethanol production were investigated. The variables studied were the saccharification time, weight of dry yeast Saccharomyces cerevisiae added in the starter culture (2.5, 5, 10, 15, 20 g) and fermentation temperature (30, 35, 40, 45, 50°C). Bioethanol production consisted of the enzymatic hydrolysis (liquefaction and saccharification), and fermentation. For liquefaction, 1.6% v/w α-amylase enzyme, 1 hour, T = 95-100° C, pH 6 were used. For saccharification, 3.2% v/w b-amylase enzyme, time 4,8,24,48 hours, T = 60°C, pH 5 were used. For fermentation, Saccharomyces cerevisiae yeast were used with conditions of time for 120 hours, pH 4.5. The effect of dry yeast weight and fermentation temperature indicated that 15 g yeast weight and temperature 30° C were found to be the best condition which resulted the highest ethanol concentration of 85.20 g/L and 79.94 g/L for sorghum and iles-iles flour, respectively.

Estrogenic activity of phenolic additives determined by an in vitro yeast bioassay.

PubMed Central

Miller, D; Wheals, B B; Beresford, N; Sumpter, J P

2001-01-01

We used a recombinant yeast estrogen assay to assess the activity of 73 phenolic additives that are used as sunscreens, preservatives, disinfectants, antioxidants, flavorings, or for perfumery. Thirty-two of these compounds displayed activity: 22 with potencies relative to 17beta-estradiol, ranging from 1/3,000 to < 1/3,000,000, and 10 compounds with an impaired response that could not be directly compared with 17beta-estradiol. Forty-one compounds were inactive. The major criteria for activity appear to be the presence of an unhindered phenolic OH group in a para position and a molecular weight of 140-250 Da. PMID:11266322

Bacterial vaginosis and vaginal yeast, but not vaginal cleansing, increase HIV-1 acquisition in African women.

PubMed

van de Wijgert, Janneke H H M; Morrison, Charles S; Cornelisse, Peter G A; Munjoma, Marshall; Moncada, Jeanne; Awio, Peter; Wang, Jing; Van der Pol, Barbara; Chipato, Tsungai; Salata, Robert A; Padian, Nancy S

2008-06-01

To evaluate interrelationships between bacterial vaginosis (BV), vaginal yeast, vaginal practices (cleansing and drying/tightening), mucosal inflammation, and HIV acquisition. A multicenter, prospective, observational cohort study was conducted, enrolling 4531 HIV-negative women aged 18 to 35 years attending family planning clinics in Zimbabwe and Uganda. Participants were tested for HIV and reproductive tract infections and were interviewed about vaginal practices every 3 months for 15 to 24 months. BV was measured by Gram stain Nugent scoring, vaginal yeast by wet mount, and mucosal inflammation by white blood cells on Gram stain. HIV incidence was 4.12 and 1.53 per 100 woman-years of follow-up in Zimbabwe and Uganda, respectively (a total of 213 incident infections). Women with BV or vaginal yeast were more likely to acquire HIV, especially if the condition was present at the same visit as the new HIV infection and the visit preceding it (hazard ratio [HR] = 2.50, 95% confidence interval [CI]: 1.68 to 3.72 and HR = 2.97, 95% CI: 1.67 to 5.28 for BV and yeast, respectively). These relationships did not seem to be mediated by mucosal inflammation. Vaginal drying/tightening was associated with HIV acquisition in univariate (HR = 1.49, 95% CI: 1.03 to 2.15) but not multivariate models. Vaginal cleansing was not associated with HIV acquisition. BV and yeast may contribute more to the HIV epidemic than previously thought.

PMAA-stabilized ferrofluid/chitosan/yeast composite for bioapplications

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

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

PubMed

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.

Comparison of volatiles and mosquito capture efficacy for three carbohydrate sources in a yeast-fermentation CO2 generator

USDA-ARS?s Scientific Manuscript database

Mosquito surveillance in remote areas with limited access to canisters of CO2 or dry ice will benefit from an effective alternative CO2 source. In this study, we document the differences in mosquito and non-mosquito capture rates from CO2 baited (dry ice or yeast fermentation of carbohydrates) CDC t...

The mammalian AMP-activated protein kinase complex mediates glucose regulation of gene expression in the yeast Saccharomyces cerevisiae.

PubMed

Ye, Tian; Bendrioua, Loubna; Carmena, David; García-Salcedo, Raúl; Dahl, Peter; Carling, David; Hohmann, Stefan

2014-06-05

The AMP-activated protein kinase (AMPK) controls energy homeostasis in eukaryotic cells. Here we expressed hetero-trimeric mammalian AMPK complexes in a Saccharomyces cerevisiae mutant lacking all five genes encoding yeast AMPK/SNF1 components. Certain mammalian complexes complemented the growth defect of the yeast mutant on non-fermentable carbon sources. Phosphorylation of the AMPK α1-subunit was glucose-regulated, albeit not by the Glc7-Reg1/2 phosphatase, which performs this function on yeast AMPK/SNF1. AMPK could take over SNF1 function in glucose derepression. While indirectly acting anti-diabetic drugs had no effect on AMPK in yeast, compound 991 stimulated α1-subunit phosphorylation. Our results demonstrate a remarkable functional conservation of AMPK and that glucose regulation of AMPK may not be mediated by regulatory features of a specific phosphatase. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Selection and evaluation of Debaryomyces hansenii isolates as potential bioprotective agents against toxigenic penicillia in dry-fermented sausages.

PubMed

Núñez, Félix; Lara, María S; Peromingo, Belén; Delgado, Josué; Sánchez-Montero, Lourdes; Andrade, María J

2015-04-01

Biocontrol using autochthonous Debaryomyces hansenii isolates is a potentially suitable strategy for inhibiting toxigenic moulds in dry-cured meat products. The antifungal activity of 280 D. hansenii isolated from dry-cured meat products as well as the mode of action of the most active isolates against toxigenic penicillia were evaluated in this work. A 13.9% of the D. hansenii isolates showed inhibitory activity in a radial inhibition assay. The effects on penicillia growth of both the cell-free culture filtrate and volatile compounds from active yeast isolates were analysed. Penicillia growth inhibition by D. hansenii was probably based on additive or synergistic effects of several inhibiting factors such as competition for nutrient and space, and production of soluble or volatile compounds. When four D. hansenii isolates were tested on dry-fermented sausage, two of them produced a significantly growth reduction of the ochratoxigenic Penicillium verrucosum, keeping its counts under the level considered as hazardous for the mycotoxin presence. Therefore, the use of these two D. hansenii isolates during the processing of dry-fermented meat product could be a promising tool to control toxigenic moulds in the meat industry. Copyright © 2014 Elsevier Ltd. All rights reserved.

Quality factors, antioxidant activity, and sensory properties of jet-tube dried rabbiteye blueberries.

PubMed

Pallas, Laura A; Pegg, Ronald B; Kerr, William L

2013-06-01

Rabbiteye blueberries are an excellent source of nutrients and phytochemicals. They are often dried, which can degrade health-promoting compounds. Means of shortening exposure to high-temperature drying air are desirable. Five cultivars of rabbiteye blueberries ('Premier', 'Tifblue', 'Brightwell', 'Alapaha', and 'Powderblue') were dried in a jet-tube fluidized bed air dryer with varying pretreatments including mechanical abrasion and osmotic dehydration. Drying time ranged from 66 to 95 min at 107 °C, achieving a final water activity of 0.347-0.605. Prior osmotic dehydration significantly reduced the drying time. Vacuum osmotic dehydration for 70 min achieved similar moisture contents to soaking blueberries for 24 h. Jet-tube dried blueberries exhibited greater color saturation than commercially available blueberries. While drying reduced the total monomeric anthocyanin (TMA) content, this occurred to a lesser extent than by other processing methods. The total phenolics content (TPC) and antioxidant capacity (H-ORACFL values) increased after drying. 'Premier' was the most preferred vacuum-infused dried blueberry, with a water activity (aw) of 0.53 and 157 g H2O kg(-1). 'Tifblue' was most preferred amongst the overnight-infused and also unsweetened dried blueberries. Jet-tube drying can substantially reduce drying times while yielding blueberries with good color, sensory properties, TMA, TPC, and H-ORACFL values. Furthermore, some cultivars produce better-quality dried blueberries than others. © 2012 Society of Chemical Industry.

Effect of drying on the bioactive compounds, antioxidant, antibacterial and antityrosinase activities of pomegranate peel.

PubMed

Mphahlele, Rebogile R; Fawole, Olaniyi A; Makunga, Nokwanda P; Opara, Umezuruike L

2016-05-26

The use of pomegranate peel is highly associated with its rich phenolic concentration. Series of drying methods are recommended since bioactive compounds are highly sensitive to thermal degradation. The study was conducted to evaluate the effects of drying on the bioactive compounds, antioxidant as well as antibacterial and antityrosinase activities of pomegranate peel. Dried pomegranate peels with the initial moisture content of 70.30 % wet basis were prepared by freeze and oven drying at 40, 50 and 60 °C. Difference in CIE-LAB, chroma (C*) and hue angle (h°) were determined using colorimeter. Individual polyphenol retention was determined using LC-MS and LC-MS(E) while total phenolics concentration (TPC), total flavonoid concentration (TFC), total tannins concentration (TTC) and vitamin C concentration were measured using colorimetric methods. The antioxidant activity was measured by radical scavenging activity (RSA) and ferric reducing antioxidant power (FRAP). Furthermore, the antibacterial activity of methanolic peel extracts were tested on Gram negative (Escherichia coli and Klebsiella pneumonia) and Gram positive bacteria (Staphylococcus aureus and Bacillus subtilis) using the in vitro microdilution assays. Tyrosinase enzyme inhibition was investigated against monophenolase (tyrosine) and diphenolase (DOPA), with arbutin as positive controls. Oven drying at 60 °C resulted in high punicalin concentration (888.04 ± 141.03 mg CE/kg dried matter) along with poor red coloration (high hue angle). Freeze dried peel contained higher catechin concentration (674.51 mg/kg drying matter) + catechin and -epicatechin (70.56 mg/kg drying matter) compared to oven dried peel. Furthermore, freeze dried peel had the highest total phenolic, tannin and flavonoid concentrations compared to oven dried peel over the temperature range studied. High concentration of vitamin C (31.19 μg AAE/g dried matter) was observed in the oven dried (40 °C) pomegranate peel

The Yeast Copper Response Is Regulated by DNA Damage

PubMed Central

Dong, Kangzhen; Addinall, Stephen G.; Lydall, David

2013-01-01

Copper is an essential but potentially toxic redox-active metal, so the levels and distribution of this metal are carefully regulated to ensure that it binds to the correct proteins. Previous studies of copper-dependent transcription in the yeast Saccharomyces cerevisiae have focused on the response of genes to changes in the exogenous levels of copper. We now report that yeast copper genes are regulated in response to the DNA-damaging agents methyl methanesulfonate (MMS) and hydroxyurea by a mechanism(s) that requires the copper-responsive transcription factors Mac1 and AceI, copper superoxide dismutase (Sod1) activity, and the Rad53 checkpoint kinase. Furthermore, in copper-starved yeast, the response of the Rad53 pathway to MMS is compromised due to a loss of Sod1 activity, consistent with the model that yeast imports copper to ensure Sod1 activity and Rad53 signaling. Crucially, the Mac1 transcription factor undergoes changes in its redox state in response to changing levels of copper or MMS. This study has therefore identified a novel regulatory relationship between cellular redox, copper homeostasis, and the DNA damage response in yeast. PMID:23959798

Impact of Dry Eye Symptoms and Daily Activities in a Modern Office.

PubMed

van Tilborg, Mirjam M; Murphy, Paul J; Evans, Katharine S

2017-06-01

Modern offices and the use of electronic devices are increasing factors in work-related eye symptoms. However, symptoms of eye fatigue or dry eye sensation can be mixed and confusing. This study surveys the eye symptoms reported during a working day at modern offices to investigate the possible inhibition on daily work activities. Two online digital surveys were sent to three different work locations, by direct e-mail. Survey A consisted of 14 questions that investigated eye symptoms experienced during daily activities at work and the impact on daily activities. Survey B consisted of four general questions, the Dutch Ocular Surface Disease Index, the Work Productivity and Activity Index, and the Illness Perception Questionnaire. A total of 505 participants completed survey A, and 213 completed survey B. The participants reported that a high proportion of their day was spent working on a computer (60%). The majority experienced an air draft (79.1%) and had no adjustable light (81.5%) at their workspace. Dry eye-related symptoms were reported at a significantly higher frequency at work than at home (P < .001). Up to 70% experienced some inhibition of daily activity at work due to eye symptoms, with more than 5% experiencing symptoms most or all of the time. Indoor environment, work environment, and general health were perceived as the main reasons for developing dry eye. Compared with males, females showed a statistically significant higher Ocular Surface Disease Index score (P < .001) and experienced more inhibition and adverse effects on daily life and work productivity. This investigation shows that dry eye symptoms have a negative impact on daily activities at work. These findings suggest that multidisciplinary understanding of the negative impact of dry eye by a range of specialists will be of help in managing work-related dry eye.

Turboexpanders with dry gas seals and active magnetic bearings in hydrocarbon processing

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

Agahi, R.R.

1999-07-01

Since its first application in hydrocarbon processing in the early 1960s, turboexpander design has changed, evolved and improved tremendously. Today, hydrocarbon process designers use turboexpanders for almost all hydrocarbon liquid rejection and hydrocarbon dew point control for onshore and offshore installations. There are presently more than 3,000 turboexpanders operating in hydrocarbon gas processing plants worldwide. Due to the wide application of turboexpanders in hydrocarbon processing, the API-617 committee has assigned a task force to prepare an appendix to API-617 to cover design and manufacturing standards for turboexpanders. Dry gas seals (DGS) were cautiously introduced in the early 1980s for compressorsmore » used in hydrocarbon processing. It took almost a decade before dry gas seals found their application in turboexpanders. Dry gas seals were originally utilized to protect cryogenic hydrocarbon process gas from contamination by lubricating oil. Later on, dry gas seals were used to minimized hydrocarbon process gas leakage and also to provide an inert-gas-purged environment for both oil bearings and active magnetic bearings. The former eliminates the lubricating oil dilution problem and the latter made certification of active magnetic bearings by international certifying agencies possible. Active magnetic bearings (AMB), similar to dry gas seals, were originally introduced into hydrocarbon process gas compressors in the mid 1980s. The hydrocarbon processing industry waited half a decade to adopt this innovative technology for turboexpanders in the hydrocarbon process. The first turboexpander with active magnetic bearings was installed on an offshore platform in 1991. High reliability, low capital investment, low capital investment, low operating costs and more compact design have accelerated demand in recent years for turboexpanders with active magnetic bearings. In this paper, the author describes the technology of turboexpanders with dry gas

Virgin olive oil yeasts: A review.

PubMed

Ciafardini, Gino; Zullo, Biagi Angelo

2018-04-01

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

Chromosomal Aneuploidy Improves the Brewing Characteristics of Sake Yeast.

PubMed

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

2017-12-15

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

Chromosomal Aneuploidy Improves the Brewing Characteristics of Sake Yeast

PubMed Central

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

2017-01-01

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

Yeast Breads. Learning Activity Pack and Instructor's Guide 5.15a. Commercial Foods and Culinary Arts Competency-Based Series. Section 5: Basic Food Preparation.

ERIC Educational Resources Information Center

Florida State Univ., Tallahassee. Center for Studies in Vocational Education.

This document consists of a learning activity packet (LAP) for the student and an instructor's guide for the teacher. The LAP is intended to acquaint occupational home economics students with yeast breads and their ingredients. Illustrated information sheets and learning activities are provided in these areas: yeast breads and their ingredients,…

Yeast RNA viruses as indicators of exosome activity: human exosome hCsl4p participates in RNA degradation in Saccharomyces cerevisiae'.

PubMed

Ramírez-Garrastacho, Manuel; Esteban, Rosa

2011-12-01

The exosome is an evolutionarily conserved 10-mer complex involved in RNA metabolism, located in both the nucleus and the cytoplasm. The cytoplasmic exosome plays an important role in mRNA turnover through its 3'→5' exonucleolytic activity. The superkiller (SKI) phenotype of yeast was originally identified as an increase of killer toxin production due to elevated levels of the L-A double-stranded RNA (dsRNA) Totivirus and its satellite toxin-encoding M dsRNA. Most SKI genes were later shown to be either components of the exosome or modulators of its activity. Variations in the amount of Totivirus are, thus, good indicators of yeast exosome activity, and can be used to analyse its components. Furthermore, if exosome proteins of higher eukaryotes were functional in S. cerevisiae, these viruses would provide a simple tool to analyse their function. In this work, we have found that hCSL4, the human orthologue of SKI4 in the yeast exosome, rescues the null phenotype of the deletion mutant. hCsl4p shares with Ski4p conserved S1 RNA-binding domains, but lacks the N-terminal third of Ski4p. Nevertheless, it interacts with the Dis3p exonuclease of yeast exosome, and partially complements the superkiller phenotype of ski4-1 mutation. The elimination of the N-terminal third of Ski4p does not affect its activity, indicating that it is dispensable for RNA degradation. We have also identified the point mutation G152E in hCSL4, equivalent to the ski4-1 mutation G253E, which impairs the activity of the protein, thus validating our approach of using yeast RNA virus to analyse the exosome of higher eukaryotes. Copyright © 2011 John Wiley & Sons, Ltd.

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

PubMed

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

2014-03-01

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

Production of the forskolin precursor 11β-hydroxy-manoyl oxide in yeast using surrogate enzymatic activities.

PubMed

Ignea, Codruta; Ioannou, Efstathia; Georgantea, Panagiota; Trikka, Fotini A; Athanasakoglou, Anastasia; Loupassaki, Sofia; Roussis, Vassilios; Makris, Antonios M; Kampranis, Sotirios C

2016-02-26

Several plant diterpenes have important biological properties. Among them, forskolin is a complex labdane-type diterpene whose biological activity stems from its ability to activate adenylyl cyclase and to elevate intracellular cAMP levels. As such, it is used in the control of blood pressure, in the protection from congestive heart failure, and in weight-loss supplements. Chemical synthesis of forskolin is challenging, and production of forskolin in engineered microbes could provide a sustainable source. To this end, we set out to establish a platform for the production of forskolin and related epoxy-labdanes in yeast. Since the forskolin biosynthetic pathway has only been partially elucidated, and enzymes involved in terpene biosynthesis frequently exhibit relaxed substrate specificity, we explored the possibility of reconstructing missing steps of this pathway employing surrogate enzymes. Using CYP76AH24, a Salvia pomifera cytochrome P450 responsible for the oxidation of C-12 and C-11 of the abietane skeleton en route to carnosic acid, we were able to produce the forskolin precursor 11β-hydroxy-manoyl oxide in yeast. To improve 11β-hydroxy-manoyl oxide production, we undertook a chassis engineering effort involving the combination of three heterozygous yeast gene deletions (mct1/MCT1, whi2/WHI2, gdh1/GDH1) and obtained a 9.5-fold increase in 11β-hydroxy-manoyl oxide titers, reaching 21.2 mg L(-1). In this study, we identify a surrogate enzyme for the specific and efficient hydroxylation of manoyl oxide at position C-11β and establish a platform that will facilitate the synthesis of a broad range of tricyclic (8,13)-epoxy-labdanes in yeast. This platform forms a basis for the heterologous production of forskolin and will facilitate the elucidation of subsequent steps of forskolin biosynthesis. In addition, this study highlights the usefulness of using surrogate enzymes for the production of intermediates of complex biosynthetic pathways. The combination of

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

PubMed Central

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

1999-01-01

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

Inaccurate DNA Synthesis in Cell Extracts of Yeast Producing Active Human DNA Polymerase Iota

PubMed Central

Makarova, Alena V.; Grabow, Corinn; Gening, Leonid V.; Tarantul, Vyacheslav Z.; Tahirov, Tahir H.; Bessho, Tadayoshi; Pavlov, Youri I.

2011-01-01

Mammalian Pol ι has an unusual combination of properties: it is stimulated by Mn2+ ions, can bypass some DNA lesions and misincorporates “G” opposite template “T” more frequently than incorporates the correct “A.” We recently proposed a method of detection of Pol ι activity in animal cell extracts, based on primer extension opposite the template T with a high concentration of only two nucleotides, dGTP and dATP (incorporation of “G” versus “A” method of Gening, abbreviated as “misGvA”). We provide unambiguous proof of the “misGvA” approach concept and extend the applicability of the method for the studies of variants of Pol ι in the yeast model system with different cation cofactors. We produced human Pol ι in baker's yeast, which do not have a POLI ortholog. The “misGvA” activity is absent in cell extracts containing an empty vector, or producing catalytically dead Pol ι, or Pol ι lacking exon 2, but is robust in the strain producing wild-type Pol ι or its catalytic core, or protein with the active center L62I mutant. The signature pattern of primer extension products resulting from inaccurate DNA synthesis by extracts of cells producing either Pol ι or human Pol η is different. The DNA sequence of the template is critical for the detection of the infidelity of DNA synthesis attributed to DNA Pol ι. The primer/template and composition of the exogenous DNA precursor pool can be adapted to monitor replication fidelity in cell extracts expressing various error-prone Pols or mutator variants of accurate Pols. Finally, we demonstrate that the mutation rates in yeast strains producing human DNA Pols ι and η are not elevated over the control strain, despite highly inaccurate DNA synthesis by their extracts. PMID:21304950

Inaccurate DNA synthesis in cell extracts of yeast producing active human DNA polymerase iota.

PubMed

Makarova, Alena V; Grabow, Corinn; Gening, Leonid V; Tarantul, Vyacheslav Z; Tahirov, Tahir H; Bessho, Tadayoshi; Pavlov, Youri I

2011-01-31

Mammalian Pol ι has an unusual combination of properties: it is stimulated by Mn(2+) ions, can bypass some DNA lesions and misincorporates "G" opposite template "T" more frequently than incorporates the correct "A." We recently proposed a method of detection of Pol ι activity in animal cell extracts, based on primer extension opposite the template T with a high concentration of only two nucleotides, dGTP and dATP (incorporation of "G" versus "A" method of Gening, abbreviated as "misGvA"). We provide unambiguous proof of the "misGvA" approach concept and extend the applicability of the method for the studies of variants of Pol ι in the yeast model system with different cation cofactors. We produced human Pol ι in baker's yeast, which do not have a POLI ortholog. The "misGvA" activity is absent in cell extracts containing an empty vector, or producing catalytically dead Pol ι, or Pol ι lacking exon 2, but is robust in the strain producing wild-type Pol ι or its catalytic core, or protein with the active center L62I mutant. The signature pattern of primer extension products resulting from inaccurate DNA synthesis by extracts of cells producing either Pol ι or human Pol η is different. The DNA sequence of the template is critical for the detection of the infidelity of DNA synthesis attributed to DNA Pol ι. The primer/template and composition of the exogenous DNA precursor pool can be adapted to monitor replication fidelity in cell extracts expressing various error-prone Pols or mutator variants of accurate Pols. Finally, we demonstrate that the mutation rates in yeast strains producing human DNA Pols ι and η are not elevated over the control strain, despite highly inaccurate DNA synthesis by their extracts.

Variation of the Phytochemical Constituents and Antioxidant Activities of Zingiber officinale var. rubrum Theilade Associated with Different Drying Methods and Polyphenol Oxidase Activity.

PubMed

Ghasemzadeh, Ali; Jaafar, Hawa Z E; Rahmat, Asmah

2016-06-17

The effects of different drying methods (freeze drying, vacuum oven drying, and shade drying) on the phytochemical constituents associated with the antioxidant activities of Z. officinale var. rubrum Theilade were evaluated to determine the optimal drying process for these rhizomes. Total flavonoid content (TFC), total phenolic content (TPC), and polyphenol oxidase (PPO) activity were measured using the spectrophotometric method. Individual phenolic acids and flavonoids, 6- and 8-gingerol and shogaol were identified by ultra-high performance liquid chromatography method. Ferric reducing antioxidant potential (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays were used for the evaluation of antioxidant activities. The highest reduction in moisture content was observed after freeze drying (82.97%), followed by vacuum oven drying (80.43%) and shade drying (72.65%). The highest TPC, TFC, and 6- and 8-shogaol contents were observed in samples dried by the vacuum oven drying method compared to other drying methods. The highest content of 6- and 8-gingerol was observed after freeze drying, followed by vacuum oven drying and shade drying methods. Fresh samples had the highest PPO activity and lowest content of flavonoid and phenolic acid compounds compared to dried samples. Rhizomes dried by the vacuum oven drying method represent the highest DPPH (52.9%) and FRAP activities (566.5 μM of Fe (II)/g DM), followed by freeze drying (48.3% and 527.1 μM of Fe (II)/g DM, respectively) and shade drying methods (37.64% and 471.8 μM of Fe (II)/g DM, respectively) with IC50 values of 27.2, 29.1, and 34.8 μg/mL, respectively. Negative and significant correlations were observed between PPO and antioxidant activity of rhizomes. Vacuum oven dried rhizomes can be utilized as an ingredient for the development of value-added food products as they contain high contents of phytochemicals with valuable antioxidant potential.

Yeast Based Sensors

NASA Astrophysics Data System (ADS)

Shimomura-Shimizu, Mifumi; Karube, Isao

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

Yeast cell surface display: An efficient strategy for improvement of bioethanol fermentation performance.

PubMed

Chen, Xianzhong

2017-03-04

The cell surface serves as a functional interface between the inside and the outside of the cell. Within the past 20 y the ability of yeast (Saccharomyces cerevisiae) to display heterologous proteins on the cell surface has been demonstrated. Furthermore, S. cerevisiae has been both developed and applied in expression of various proteins on the cell surface. Using this novel and useful strategy, proteins and peptides of various kinds can be displayed on the yeast cell surface by fusing the protein of interest with the glycosylphosphatidylinositol (GPI)-anchoring system. Consolidated bioprocessing (CBP) using S. cerevisiae represents a promising technology for bioethanol production. However, further work is needed to improve the fermentation performance. There is some excellent previous research regarding construction of yeast biocatalyst using the surface display system to decrease cost, increase efficiency of ethanol production and directly utilize starch or biomass for fuel production. In this commentary, we reviewed the yeast surface display system and highlighted recent work. Additionally, the strategy for decrease of phytate phosphate content in dried distillers grains with solubles (DDGS) by display of phytase on the yeast cell surface is discussed.

Yeast cell surface display: An efficient strategy for improvement of bioethanol fermentation performance

PubMed Central

Chen, Xianzhong

2017-01-01

ABSTRACT The cell surface serves as a functional interface between the inside and the outside of the cell. Within the past 20 y the ability of yeast (Saccharomyces cerevisiae) to display heterologous proteins on the cell surface has been demonstrated. Furthermore, S. cerevisiae has been both developed and applied in expression of various proteins on the cell surface. Using this novel and useful strategy, proteins and peptides of various kinds can be displayed on the yeast cell surface by fusing the protein of interest with the glycosylphosphatidylinositol (GPI)-anchoring system. Consolidated bioprocessing (CBP) using S. cerevisiae represents a promising technology for bioethanol production. However, further work is needed to improve the fermentation performance. There is some excellent previous research regarding construction of yeast biocatalyst using the surface display system to decrease cost, increase efficiency of ethanol production and directly utilize starch or biomass for fuel production. In this commentary, we reviewed the yeast surface display system and highlighted recent work. Additionally, the strategy for decrease of phytate phosphate content in dried distillers grains with solubles (DDGS) by display of phytase on the yeast cell surface is discussed. PMID:27459271

Effect of emulsification and spray-drying microencapsulation on the antilisterial activity of transcinnamaldehyde.

PubMed

Trinh, Nga-Thi-Thanh; Lejmi, Raja; Gharsallaoui, Adem; Dumas, Emilie; Degraeve, Pascal; Thanh, Mai Le; Oulahal, Nadia

2015-01-01

Spray-dried redispersible transcinnamaldehyde (TC)-in-water emulsions were prepared in order to preserve its antibacterial activity; 5% (w/w) TC emulsions were first obtained with a rotor-stator homogeniser in the presence of either soybean lecithin or sodium caseinate as emulsifiers. These emulsions were mixed with a 30% (w/w) maltodextrin solution before feeding a spray-dryer. The antibacterial activity of TC alone, TC emulsions with and without maltodextrin before and after spray-drying were assayed by monitoring the growth at 30 °C of Listeria innocua in their presence and in their absence (control). Whatever the emulsifier used, antilisterial activity of TC was increased following its emulsification. However, reconstituted spray-dried emulsions stabilised by sodium caseinate had a higher antibacterial activity suggesting that they better resisted to spray-drying. This was consistent with observation that microencapsulation efficiencies were 27.6% and 78.7% for emulsions stabilised by lecithin and sodium caseinate, respectively.

Biofortification of folates in white wheat bread by selection of yeast strain and process.

PubMed

Hjortmo, Sofia; Patring, Johan; Jastrebova, Jelena; Andlid, Thomas

2008-09-30

We here demonstrate that folate content in yeast fermented food can be dramatically increased by using a proper (i) yeast strain and (ii) cultivation procedure for the selected strain prior to food fermentation. Folate levels were 3 to 5-fold higher in white wheat bread leavened with a Saccharomyces cerevisiae strain CBS7764, cultured in defined medium and harvested in the respiro-fermentative phase of growth prior to dough preparation (135-139 microg/100 dry matter), compared to white wheat bread leavened with commercial Baker's yeast (27-43 microg/100 g). The commercial Baker's yeast strain had been industrially produced, using a fed-batch process, thereafter compressed and stored in the refrigerator until bakings were initiated. This strategy is an attractive alternative to fortification of bread with synthetically produced folic acid. By using a high folate producing strain cultured a suitable way folate levels obtained were in accordance with folic acid content in fortified cereal products.

Kinetics of growth and sugar consumption in yeasts.

PubMed

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

1993-01-01

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

Local climatic conditions constrain soil yeast diversity patterns in Mediterranean forests, woodlands and scrub biome.

PubMed

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

2016-02-01

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

Budding Yeast Silencing Complexes and Regulation of Sir2 Activity by Protein-Protein Interactions

PubMed Central

Tanny, Jason C.; Kirkpatrick, Donald S.; Gerber, Scott A.; Gygi, Steven P.; Moazed, Danesh

2004-01-01

Gene silencing in the budding yeast Saccharomyces cerevisiae requires the enzymatic activity of the Sir2 protein, a highly conserved NAD-dependent deacetylase. In order to study the activity of native Sir2, we purified and characterized two budding yeast Sir2 complexes: the Sir2/Sir4 complex, which mediates silencing at mating-type loci and at telomeres, and the RENT complex, which mediates silencing at the ribosomal DNA repeats. Analyses of the protein compositions of these complexes confirmed previously described interactions. We show that the assembly of Sir2 into native silencing complexes does not alter its selectivity for acetylated substrates, nor does it allow the deacetylation of nucleosomal histones. The inability of Sir2 complexes to deacetylate nucleosomes suggests that additional factors influence Sir2 activity in vivo. In contrast, Sir2 complexes show significant enhancement in their affinities for acetylated substrates and their sensitivities to the physiological inhibitor nicotinamide relative to recombinant Sir2. Reconstitution experiments showed that, for the Sir2/Sir4 complex, these differences stem from the physical interaction of Sir2 with Sir4. Finally, we provide evidence that the different nicotinamide sensitivities of Sir2/Sir4 and RENT in vitro could contribute to locus-specific differences in how Sir2 activity is regulated in vivo. PMID:15282295

Potential of yeasts isolated from dry-cured ham to control ochratoxin A production in meat models.

PubMed

Peromingo, Belén; Núñez, Félix; Rodríguez, Alicia; Alía, Alberto; Andrade, María J

2018-03-02

The environmental conditions reached during the ripening of dry-cured meat products favour the proliferation of moulds on their surface. Some of these moulds are hazardous to consumers because of their ability to produce ochratoxin A (OTA). Biocontrol using Debaryomyces hansenii could be a suitable strategy to prevent the growth of ochratoxigenic moulds and OTA accumulation in dry-cured meat products. The aim of this work was to evaluate the ability of two strains of D. hansenii to control the growth and OTA production of Penicillium verrucosum in a meat model under water activities (a w ) values commonly reached during the dry-cured meat product ripening. The presence of D. hansenii strains triggered a lengthening of the lag phase and a decrease of the growth rate of P. verrucosum in meat-based media at 0.97 and 0.92 a w . Both D. hansenii strains significantly reduced OTA production (between 85.16 and 92.63%) by P. verrucosum in the meat-based medium at 0.92 a w . Neither absorption nor detoxification of OTA by D. hansenii strains seems to be involved. However, a repression of the expression of the non-ribosomal peptide synthetase (otanpsPN) gene linked to the OTA biosynthetic pathway was observed in the presence of D. hansenii. To confirm the protective role of D. hansenii strains, they were inoculated together with P. verrucosum Pv45 in dry-fermented sausage and dry-cured ham slices. Although P. verrucosum Pv45 counts were not affected by the presence of D. hansenii in both meat matrices, a reduction of OTA amount was observed. Therefore, the effect of D. hansenii strains on OTA accumulation should be attributed to a reduction at transcriptional level. Consequently, native D. hansenii can be useful as biocontrol agent in dry-cured meat products for preventing the hazard associated with the presence of OTA. Copyright © 2018 Elsevier B.V. All rights reserved.

Yeasts of the soil – obscure but precious

PubMed Central

2018-01-01

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

Carpoglyphus lactis (Acari: Astigmata) from various dried fruits differed in associated micro-organisms.

PubMed

Hubert, J; Nesvorná, M; Kopecký, J; Ságová-Marečková, M; Poltronieri, P

2015-02-01

Carpoglyphus lactis is a stored product mite infesting saccharide-rich stored commodities including dried fruits, wine, beer, milk products, jams and honey. The association with micro-organisms can improve the survival of mites on dried fruits. The microbial communities associated with C. lactis were studied in specimens originating from the packages of dried apricot, plums and figs and compared to the laboratory strain reared on house dust mite diet (HDMd). Clone libraries of bacterial 16S rRNA gene and fungal internal transcribed spacer (ITS) region were constructed and analysed by operational taxonomic unit (OTU) approach. The 16S rRNA gene libraries differed among the compared diets. The sequences classified to the genera Leuconostoc, Elizabethkingia, Ewingella, Erwinia, Bacillus and Serratia were prevailing in mites sampled from the dried fruits. The ITS library showed smaller differences between the laboratory strain on HDMd and the isolates from dried fruits packages, with the exception of the mite strain from dried plums. The population growth was used as an indirect indicator of fitness and decreased in the order from yeast diet to HDMd and dried fruits. The treatment and pretreatment of mites by antibiotics did not reveal the presence of antagonistic bacteria which might slow down the C. lactis population growth. The shifts of the microbial community in the gut of C. lactis were induced by the diet changes. The identified yeasts and bacteria are suggested as the main food source of stored product mites on dried fruits. The study describes the adaptation of C. lactis to feeding on dried fruits including the interaction with micro-organisms. We also identified potentially pathogenic bacteria carried by the mites to dried fruits for human consumption. © 2014 The Society for Applied Microbiology.

The Influence of Different Air-Drying Conditions on Bioactive Compounds and Antioxidant Activity of Berries.

PubMed

Bustos, Mariela C; Rocha-Parra, Diego; Sampedro, Ines; de Pascual-Teresa, Sonia; León, Alberto E

2018-03-21

The aim of the present research was to study the effect of convective drying on color, bioactive compounds, and antioxidant activity of berry fruits and to chemically characterize the polyphenolic composition of raspberry, boysenberry, redcurrants, and blackcurrants fruit. Drying berries at 65 °C provoked the best conservations of color, particularly for boysenberry and blackcurrant. Drying at 65 °C was also the condition that showed higher level of polyphenols, while drying at 50 or 130 °C showed above % degradation of them due to the long time or high temperature drying. Radical scavenging activity was the predominant antioxidant mechanism in all samples, with 65 °C dried berries being the most active ones possibly because of polyphenol depolymerization. The anthocyanin profile showed that delphinidin and cyanidin derivatives were the most abundant anthocyanidins with different predominance between berry genera. Degradation of anthocyanins was increased with drying temperature been Cy 3-glucoside and Cy 3-rutinoside the most abundant.

Comparison of carbohydrate sources in yeast-fermentation CO2 generators for mosquito surveillance

USDA-ARS?s Scientific Manuscript database

Mosquito surveillance in remote areas with limited access to canisters of CO2 or dry ice will benefit from an effective alternative CO2 source, such as the natural production of CO2 from yeast fermentation of several carbohydrate sources. In this study, we document the differences in mosquito and n...

Yeast Infection (Vaginal)

MedlinePlus

Yeast infection (vaginal) Overview A vaginal yeast infection is a fungal infection that causes irritation, discharge and intense itchiness ... symptoms Causes The fungus candida causes a vaginal yeast infection. Your vagina naturally contains a balanced mix of yeast, including ...

Free radical interactions between raw materials in dry soup powder.

PubMed

Raitio, Riikka; Orlien, Vibeke; Skibsted, Leif H

2011-12-01

Interactions at the free radical level were observed between dry ingredients in cauliflower soup powder, prepared by dry mixing of ingredients and rapeseed oil, which may be of importance for quality deterioration of such dry food products. The free radical concentrations of cauliflower soup powder, obtained by electron spin resonance (ESR) spectroscopy, rapidly become smaller during storage (40°C and relative humidity of 75%) than the calculated concentrations of free radicals based on the free radical concentrations of the powder ingredients used to make the soup powder and stored separately under similar conditions. Similarly, free radical concentrations decreased faster when any combination of two powder ingredients (of the three major ingredients of the soup powder) were mixed together and stored at 50°C for 1week than when each powder component was stored separately. Furthermore, yeast extract powder was found to play a key role when free radical interactions between powder ingredients occurred. The incubation of rapeseed oil with powder ingredients at 45°C for 24h, indicated the ability of cauliflower powder to increase the concentration of hydroperoxides in rapeseed oil, while yeast extract powder was found to prevent this hydroperoxide formation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Species-specific activation of Cu/Zn SOD by its CCS copper chaperone in the pathogenic yeast Candida albicans.

PubMed

Gleason, Julie E; Li, Cissy X; Odeh, Hana M; Culotta, Valeria C

2014-06-01

Candida albicans is a pathogenic yeast of important public health relevance. Virulence of C. albicans requires a copper and zinc containing superoxide dismutase (SOD1), but the biology of C. albicans SOD1 is poorly understood. To this end, C. albicans SOD1 activation was examined in baker's yeast (Saccharomyces cerevisiae), a eukaryotic expression system that has proven fruitful for the study of SOD1 enzymes from invertebrates, plants, and mammals. In spite of the 80% similarity between S. cerevisiae and C. albicans SOD1 molecules, C. albicans SOD1 is not active in S. cerevisiae. The SOD1 appears incapable of productive interactions with the copper chaperone for SOD1 (CCS1) of S. cerevisiae. C. albicans SOD1 contains a proline at position 144 predicted to dictate dependence on CCS1. By mutation of this proline, C. albicans SOD1 gained activity in S. cerevisiae, and this activity was independent of CCS1. We identified a putative CCS1 gene in C. albicans and created heterozygous and homozygous gene deletions at this locus. Loss of CCS1 resulted in loss of SOD1 activity, consistent with its role as a copper chaperone. C. albicans CCS1 also restored activity to C. albicans SOD1 expressed in S. cerevisiae. C. albicans CCS1 is well adapted for activating its partner SOD1 from C. albicans, but not SOD1 from S. cerevisiae. In spite of the high degree of homology between the SOD1 and CCS1 molecules in these two fungal species, there exists a species-specific barrier in CCS-SOD interactions which may reflect the vastly different lifestyles of the pathogenic versus the noninfectious yeast.

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

NASA Astrophysics Data System (ADS)

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

1993-09-01

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

Identification of yeasts during alcoholic fermentation of tchapalo, a traditional sorghum beer from Côte d'Ivoire.

PubMed

N'guessan, Kouadio Florent; Brou, Kouakou; Jacques, Noémie; Casaregola, Serge; Dje, Koffi Marcellin

2011-05-01

This study investigated the diversity and dynamics of yeasts involved in alcoholic fermentation of a traditional sorghum beer from Côte d'Ivoire, tchapalo. A total of 240 yeast strains were isolated from fermenting sorghum wort inoculated with dry yeast from two geographic regions of Côte d'Ivoire (Abidjan and Bondoukou). Initial molecular identification to the species level was carried out using RFLP of PCR-amplified internal transcribed spacers of rDNA (ITS1-5.8S-ITS2). Ten different profiles were obtained from the restriction of PCR products with the three endonucleases HaeIII, CfoI and HinfI. Sequence analysis of the D1/D2 domain of the 26S rDNA and the ACT1 gene allowed us to assign these groups to six different species: Saccharomyces cerevisiae-like, Candida tropicalis, Pichia kudriavzevii, Pichia kluyveri, Kodamaea ohmeri and Meyerozyma caribbica. The most frequent species associated with tchapalo fermentation was S. cerevisiae-like (87.36%), followed by C. tropicalis (5.45%) and M. caribbica (2.71%). S. cerevisiae-like strains were diploid heterozygotes and exhibited three to four nucleotides divergence from the type strain in the D1/D2 domain and several indels in the more discriminant sequence of the intron of the ACT1 gene. During the process, the yeast species isolated and their frequencies varied according to the geographic origin of the dry yeast. The occurrence of some species was sporadic and only two non-Saccharomyces species were found in the final product.

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

PubMed

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

2016-10-24

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

Comparison of the Petrifilm dry rehydratable film and conventional culture methods for enumeration of yeasts and molds in foods: collaborative study.

PubMed

Knight, M T; Newman, M C; Benzinger, M J; Neufang, K L; Agin, J R; McAllister, J S; Ramos, M

1997-01-01

A collaborative study was performed involving 18 laboratories and 6 food types to compare 3M Petrifilm yeast and mold count plates with the method described in the U.S. Food and Drug Administration's Bacteriological Analytical Manual. Four species of mold and 2 species of yeast were used to inoculate the following foods: hot dogs, corn meal, ketchup, orange juice, yogurt, and cake mix. Each collaborator received 15 samples of each food type: 5 low-level inoculations, 5 high-level inoculations, and 5 uninoculated samples. There was no significant difference between the means of the 2 methods for any product or inoculation level. The Petrifilm yeast and mold count plate method for enumeration of yeasts and molds in foods has been adopted first action by AOAC INTERNATIONAL.

Applications of yeast surface display for protein engineering

PubMed Central

Cherf, Gerald M.; Cochran, Jennifer R.

2015-01-01

The method of displaying recombinant proteins on the surface of Saccharomyces cerevisiae via genetic fusion to an abundant cell wall protein, a technology known as yeast surface display, or simply, yeast display, has become a valuable protein engineering tool for a broad spectrum of biotechnology and biomedical applications. This review focuses on the use of yeast display for engineering protein affinity, stability, and enzymatic activity. Strategies and examples for each protein engineering goal are discussed. Additional applications of yeast display are also briefly presented, including protein epitope mapping, identification of protein-protein interactions, and uses of displayed proteins in industry and medicine. PMID:26060074

Micro-Biocidal Activity of Yeast Cells by Needle Plasma Irradiation at Atmospheric Pressure

NASA Astrophysics Data System (ADS)

Kurumi, Satoshi; Takahashi, Hideyuki; Taima, Tomohito; Suzuki, Kaoru; Hirose, Hideharu; Masutani, Shigeyuki

In this study, we report on the biocidal activity technique by needle helium plasma irradiation at atmospheric pressure using borosilicate capillary nozzle to apply for the oral surgery. The diameter of needle plasma was less than 50 µm, and temperature of plasma irradiated area was less than body temperature. Needle plasma showed emission due to OH and O radical. Raman spectra and methylene blue stain showed yeast cells were inactivated by needle plasma irradiation.

A polyphasic study on the taxonomic position of industrial sour dough yeasts.

PubMed

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

1999-02-01

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

Quantitative study of lipase secretion, extracellular lipolysis, and lipid storage in the yeast Yarrowia lipolytica grown in the presence of olive oil: analogies with lipolysis in humans.

PubMed

Najjar, Amal; Robert, Sylvie; Guérin, Clémence; Violet-Asther, Michèle; Carrière, Frédéric

2011-03-01

Lipase secretion, extracellular lipolysis, and fatty acid uptake were quantified in the yeast Yarrowia lipolytica grown in the presence of olive oil and/or glucose. Specific lipase assays, Western blot analysis, and ELISA indicated that most of the lipase activity measured in Y. lipolytica cultures resulted from the YLLIP2 lipase. Lipase production was triggered by olive oil and, during the first hours of culture, most of the lipase activity and YLLIP2 immunodetection remained associated with the yeast cells. YLLIP2 was then released in the culture medium before it was totally degraded by proteases. Olive oil triglycerides were largely degraded when the lipase was still attached to the cell wall. The fate of lipolysis products in the culture medium and inside the yeast cell, as well as lipid storage, was investigated simultaneously by quantitative TLC-FID and GC analysis. The intracellular levels of free fatty acids (FFA) and triglycerides increased transiently and were dependent on the carbon sources. A maximum fat storage of 37.8% w/w of yeast dry mass was observed with olive oil alone. A transient accumulation of saturated FFA was observed whereas intracellular triglycerides became enriched in unsaturated fatty acids. So far, yeasts have been mainly used for studying the intracellular synthesis, storage, and mobilization of neutral lipids. The present study shows that yeasts are also interesting models for studying extracellular lipolysis and fat uptake by the cell. The quantitative data obtained here allow for the first time to establish interesting analogies with gastrointestinal and vascular lipolysis in humans.

Effects of a spoilage yeast from silage on in vitro ruminal fermentation.

PubMed

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

2015-04-01

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

Malassezia yeasts produce a collection of exceptionally potent activators of the Ah (dioxin) receptor detected in diseased human skin

PubMed Central

Magiatis, Prokopios; Pappas, Periklis; Gaitanis, George; Mexia, Nikitia; Melliou, Eleni; Galanou, Maria; Vlachos, Christophoros; Stathopoulou, Konstantina; Skaltsounis, Alexios Leandros; Marselos, Marios; Velegraki, Aristea; Denison, Michael S.; Bassukas, Ioannis D.

2013-01-01

Malassezia yeasts are commensal microorganisms which under insufficiently understood conditions can become pathogenic. We have previously shown that specific strains isolated from diseased human skin can preferentially produce agonists of the aryl hydrocarbon receptor (AhR), whose activation has been linked to certain skin diseases. Investigation of skin scale extracts from patients with Malassezia associated diseases demonstrated 10–1000 fold higher AhR activating capacity than control skin extracts. LC/MS/MS analysis of the patients’ extracts revealed the presence of indirubin, 6-formylindolo[3,2-b]carbazole (FICZ), indolo[3,2-b]carbazole (ICZ), malassezin, and pityriacitrin. The same compounds were also identified in 9/12 Malassezia species culture extracts tested, connecting their presence in skin scales with this yeast. Studying the activity of the Malassezia culture-extracts and pure metabolites in HaCaT cells by Reverse Transcriptase Real-Time PCR revealed significant alterations in mRNA levels of the endogenous AhR-responsive genes Cyp1A1, Cyp1B1 and AhRR. Indirubin and FICZ activated AhR in HaCaT and human HepG2 cells with significantly higher, yet transient, potency as compared to the prototypical AhR ligand, dioxin. In loco synthesis of these highly potent AhR inducers by Malassezia yeasts could have a significant impact on skin homeostatic mechanisms and disease development. PMID:23448877

Malassezia yeasts produce a collection of exceptionally potent activators of the Ah (dioxin) receptor detected in diseased human skin.

PubMed

Magiatis, Prokopios; Pappas, Periklis; Gaitanis, George; Mexia, Nikitia; Melliou, Eleni; Galanou, Maria; Vlachos, Christophoros; Stathopoulou, Konstantina; Skaltsounis, Alexios Leandros; Marselos, Marios; Velegraki, Aristea; Denison, Michael S; Bassukas, Ioannis D

2013-08-01

Malassezia yeasts are commensal microorganisms, which under insufficiently understood conditions can become pathogenic. We have previously shown that specific strains isolated from diseased human skin can preferentially produce agonists of the aryl hydrocarbon receptor (AhR), whose activation has been linked to certain skin diseases. Investigation of skin scale extracts from patients with Malassezia-associated diseases demonstrated 10- to 1,000-fold higher AhR-activating capacity than control skin extracts. Liquid chromatography-tandem mass spectrometry analysis of the patients' extracts revealed the presence of indirubin, 6-formylindolo[3,2-b]carbazole (FICZ), indolo[3,2-b]carbazole (ICZ), malassezin, and pityriacitrin. The same compounds were also identified in 9 out of 12 Malassezia species culture extracts tested, connecting their presence in skin scales with this yeast. Studying the activity of the Malassezia culture extracts and pure metabolites in HaCaT cells by reverse transcriptase real-time PCR revealed significant alterations in mRNA levels of the endogenous AhR-responsive genes Cyp1A1, Cyp1B1, and AhRR. Indirubin- and FICZ-activated AhR in HaCaT and human HepG2 cells with significantly higher, yet transient, potency as compared with the prototypical AhR ligand, dioxin. In loco synthesis of these highly potent AhR inducers by Malassezia yeasts could have a significant impact on skin homeostatic mechanisms and disease development.

Obtaining a Dry Extract from the Mikania laevigata Leaves with Potential for Antiulcer Activity

PubMed Central

Pinto, Mariana Viana; Oliveira, Ezequiane Machado; Martins, Jose Luiz Rodrigues; de Paula, Jose Realino; Costa, Elson Alves; da Conceição, Edemilson Cardoso; Bara, Maria Teresa Freitas

2017-01-01

Background: Mikania laevigata leaves are commonly used in Brazil as a medicinal plant. Objective: To obtain hydroalcoholic dried extract by nebulization and evaluate its antiulcerogenic potential. Materials and Methods: Plant material and hydroalcoholic extract were processed and analyzed for their physicochemical characteristics. A method using HPLC was validated to quantify coumarin and o-coumaric acid. Hydroalcoholic extract was spray dried and the powder obtained was characterized in terms of its physicochemical parameters and potential for antiulcerogenic activity. Results: The analytical method proved to be selective, linear, precise, accurate, sensitive, and robust. M. laevigata spray dried extract was obtained using colloidal silicon dioxide as adjuvant and was shown to possess 1.83 ± 0.004% coumarin and 0.80 ± 0.012% o-coumaric acid. It showed significant antiulcer activity in a model of an indomethacin-induced gastric lesion in mice and also produced a gastroprotective effect. Conclusion: This dried extract from M. laevigata could be a promising intermediate phytopharmaceutical product. SUMMARY Research and development of standardized dried extract of Mikania laevigata leaves obtained through spray drying and the production process was monitored by the chemical profile, physicochemical properties and potential for anti-ulcerogenic activity. Abbreviations used: DE: M. laevigata spray dried extract, HE: hydroalcoholic extract. PMID:28216886

On-line carbon balance of yeast fermentations using miniaturized optical sensors.

PubMed

Beuermann, Thomas; Egly, Dominik; Geoerg, Daniel; Klug, Kerris Isolde; Storhas, Winfried; Methner, Frank-Juergen

2012-03-01

Monitoring of microbiological processes using optical sensors and spectrometers has gained in importance over the past few years due to its advantage in enabling non-invasive on-line analysis. Near-infrared (NIR) and mid-infrared (MIR) spectrometer set-ups in combination with multivariate calibrations have already been successfully employed for the simultaneous determination of different metabolites in microbiological processes. Photometric sensors, in addition to their low price compared to spectrometer set-ups, have the advantage of being compact and are easy to calibrate and operate. In this work, the detection of ethanol and CO(2) in the exhaust gas during aerobic yeast fermentation was performed by two photometric gas analyzers, and dry yeast biomass was monitored using a fiber optic backscatter set-up. The optical sensors could be easily fitted to the bioreactor and exhibited high robustness during measuring. The ethanol content of the fermentation broth was monitored on-line by measuring the ethanol concentration in the fermentation exhaust and applying a conversion factor. The vapor/liquid equilibrium and the associated conversion factor strongly depend on the process parameter temperature but not on aeration and stirring rate. Dry yeast biomass was determined in-line by a backscattering signal applying a linear calibration. An on-line balance with a recovery rate of 95-97% for carbon was achieved with the use of three optical sensors (two infrared gas analyzers and one fiber optic backscatter set-up). Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Biodiesel production from yeast Cryptococcus sp. using Jerusalem artichoke.

PubMed

Sung, Mina; Seo, Yeong Hwan; Han, Shin; Han, Jong-In

2014-03-01

Jerusalem artichoke was investigated as a cheap substrate for the heterotrophic production using a lab yeast strain Cryptococcus sp. Using Response Surface Method, 54.0% of fructose yield was achieved at 12% of dried Jerusalem artichoke powder, 0.57% of nitric acid concentration, 117°C of reaction temperature, and 49min of reaction time. At this optimal condition, nitric acid showed the best catalytic activity toward inulin hydrolysis and also the resulting fructose hydrolyte supported the highest microbial growth compared with other acids. In addition, lipid productivity of 1.73g/L/d was achieved, which is higher than a defined medium using pure fructose as a substrate. Lipid quality was also found to be generally satisfactory as a feedstock for fuel, demonstrating Jerusalem artichoke could indeed be a good and cheap option for the purpose of biodiesel production. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of jasmonic acid and yeast extract elicitation on low-molecular antioxidants and antioxidant activity of marjoram (Origanum majorana L.).

PubMed

Złotek, Urszula

2017-01-01

Elicitation, which is a way of inducing plant secondary metabolism, may be an effective method for improving the quality of plant food. The aim of this study was to determine how the application of jasmonic acid (as an abiotic elicitor) and yeast extract (as a biotic elicitor) influences the production of some bioactive compounds in marjoram and the antioxidant activity of this herb. Elicitation with 0.01 µM and 1 µM jasmonic acid as well as 0.1% and 1% yeast extracts was used for improving the health-benefiting quality of marjoram. The study focused on the effects of eliciting the level of some phytochemicals and the antioxidant activity of marjoram. There were no significant differences in total phenolic content between the elicited and control plants. In turn, the elicitation with 0.1% and 1% yeast extracts caused 1.8- and 2.5-fold increases in the ascorbic acid content in marjoram leaves, respectively. Both biotic and abiotic elicitation resulted in elevation of chlorophyll content, but only the abiotic elicitor (jasmonic acid) caused a significant increase (by over 50%) in the carotenoid content of marjoram leaves. The antiradical activity of marjoram was increased by the abiotic and biotic elicitation, whereas only the abiotic elicitation resulted in improving the reducing power of this herb. In conclusion, biotic and abiotic elicitation could be an effective strategy for improving the level of some phytochemicals, as well as the antioxidant activity of marjoram. A particularly valuable finding obtained in this study is that natural elicitors e.g. yeast extract can be equally effective in elevating the content of some bioactive compounds in herbs e.g. marjoram as an abiotic one.

Phytase-active yeasts from grain-based food and beer.

PubMed

Nuobariene, L; Hansen, A S; Jespersen, L; Arneborg, N

2011-06-01

To screen yeast strains isolated from grain-based food and beer for phytase activity to identify high phytase-active strains. The screening of phytase-positive strains was carried out at conditions optimal for leavening of bread dough (pH 5·5 and 30°C), in order to identify strains that could be used for the baking industry. Two growth-based tests were used for the initial testing of phytase-active strains. Tested strains belonged to six species: Saccharomyces cerevisiae, Saccharomyces pastorianus, Saccharomyces bayanus, Kazachstania exigua (former name Saccharomyces exiguus), Candida krusei (teleomorph Issachenkia orientalis) and Arxula adeninivorans. On the basis of initial testing results, 14 strains were selected for the further determination of extracellular and intracellular (cytoplasmic and/or cell-wall bound) phytase activities. The most prominent strains for extracellular phytase production were found to be S. pastorianus KVL008 (a lager beer strain), followed by S. cerevisiae KVL015 (an ale beer strain) and C. krusei P2 (isolated from sorghum beer). Intracellular phytase activities were relatively low in all tested strains. Herein, for the first time, beer-related strains of S. pastorianus and S. cerevisiae are reported as phytase-positive strains. The high level of extracellular phytase activity by the strains mentioned previously suggests them to be strains for the production of wholemeal bread with high content of bioavailable minerals. © 2011 The Authors. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology.

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

PubMed

Watanabe, Daisuke; Takagi, Hiroshi

2017-02-01

The 14th International Congress on Yeasts (ICY14) was held at Awaji Yumebutai International Conference Center (Awaji, Hyogo) in Japan from 11 to 15 September 2016. The main slogan of ICY14 was 'Yeasts for Global Happiness', which enabled us to acknowledge the high-potential usefulness of yeasts contributing to the global happiness in terms of food/beverage, health/medicine and energy/environment industries, as well as to basic biosciences. In addition, two more concepts were introduced: 'from Japan to the world' and 'from senior to junior'. As it was the first ICY meeting held in Japan or other Asian countries, ICY14 provided a good opportunity to widely spread the great achievements by Japanese and Asian yeast researchers, such as those by the 2016 Nobel Laureate Dr. Yoshinori Ohsumi, and also, to convey the fun and importance of yeasts to the next generation of researchers from Asia and all over the world. As a result, a total of 426 yeast lovers from 42 countries (225 overseas and 201 domestic participants) with different generations attended ICY14 to share the latest knowledge of a wide range of yeast research fields and to join active and constructive scientific discussions. © 2017 Molecular Biology Society of Japan and John Wiley & Sons Australia, Ltd.

Aromatic hydrocarbon biodegradation activates neutral lipid biosynthesis in oleaginous yeast.

PubMed

Deeba, Farha; Pruthi, Vikas; Negi, Yuvraj S

2018-05-01

In this study, the biodegradation ability of oleaginous yeast Cryptococcus psychrotolerans IITRFD for aromatic hydrocarbons (AHs) was investigated. It was found to completely degrade range of AHs such as 1 g/L phenol, 0.75 g/L naphthalene, 0.50 g/L anthracene and 0.50 g/L pyrene with lipid productivity (g/L/h) of 0.0444, 0.0441, 0.0394 and 0.0383, respectively. This work demonstrated the ring cleavage pathways of AHs by this yeast which follow ortho route for phenol and naphthalene while meta route for anthracene and pyrene degradation. The end products generated during biodegradation of AHs are feed as precursors for de novo triacylglycerols (TAG) biosynthesis pathway of oleaginous yeast. A high quantity of lipid content (46.54%) was observed on phenol as compared to lipid content on naphthalene (46.38%), anthracene (44.97%) and pyrene (44.16%). The lipid profile revealed by GC-MS analysis shows elevated monounsaturated fatty acid (MUFA) content with improved biodiesel quality. Copyright © 2018 Elsevier Ltd. All rights reserved.

Direct spray drying and microencapsulation of probiotic Lactobacillus reuteri from slurry fermentation with whey.

PubMed

Jantzen, M; Göpel, A; Beermann, C

2013-10-01

Formulations of dietary probiotics have to be robust against process conditions and have to maintain a sufficient survival rate during gastric transit. To increase efficiency of the encapsulation process and the viability of applied bacteria, this study aimed at developing spray drying and encapsulation of Lactobacillus reuteri with whey directly from slurry fermentation. Lactobacillus reuteri was cultivated in watery 20% (w/v) whey solution with or without 0·5% (w/v) yeast extract supplementation in a submerged slurry fermentation. Growth enhancement with supplement was observed. Whey slurry containing c. 10(9)  CFU g(-1) bacteria was directly spray-dried. Cell counts in achieved products decreased by 2 log cycles after drying and 1 log cycle during 4 weeks of storage. Encapsulated bacteria were distinctively released in intestinal milieu. Survival rate of encapsulated bacteria was 32% higher compared with nonencapsulated ones exposed to artificial digestive juice. Probiotic L. reuteri proliferate in slurry fermentation with yeast-supplemented whey and enable a direct spray drying in whey. The resulting microcapsules remain stable during storage and reveal adequate survival in simulated gastric juices and a distinct release in intestinal juices. Exploiting whey as a bacterial substrate and encapsulation matrix within a coupled fermentation and spray-drying process offers an efficient option for industrial production of vital probiotics. © 2013 The Society for Applied Microbiology.

Yeast as a model for Ras signalling.

PubMed

Tisi, Renata; Belotti, Fiorella; Martegani, Enzo

2014-01-01

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

Flor Yeast: New Perspectives Beyond Wine Aging

PubMed Central

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

2016-01-01

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

Activation of a yeast replication origin near a double-stranded DNA break.

PubMed

Raghuraman, M K; Brewer, B J; Fangman, W L

1994-03-01

Irradiation in the G1 phase of the cell cycle delays the onset of DNA synthesis and transiently inhibits the activation of replication origins in mammalian cells. It has been suggested that this inhibition is the result of the loss of torsional tension in the DNA after it has been damaged. Because irradiation causes DNA damage at an undefined number of nonspecific sites in the genome, it is not known how cells respond to limited DNA damage, and how replication origins in the immediate vicinity of a damage site would behave. Using the sequence-specific HO endonuclease, we have created a defined double-stranded DNA break in a centromeric plasmid in G1-arrested cells of the yeast Saccharomyces cerevisiae. We show that replication does initiate at the origin on the cut plasmid, and that the plasmid replicates early in the S phase after linearization in vivo. These observations suggest that relaxation of a supercoiled DNA domain in yeast need not inactivate replication origins within that domain. Furthermore, these observations rule out the possibility that the late replication context associated with chromosomal termini is a consequence of DNA ends.

Oxidative Stress and Programmed Cell Death in Yeast

PubMed Central

Farrugia, Gianluca; Balzan, Rena

2012-01-01

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

Antimicrobial and Probiotic Properties of Yeasts: From Fundamental to Novel Applications

PubMed Central

Hatoum, Rima; Labrie, Steve; Fliss, Ismail

2012-01-01

The yeasts constitute a large and heterogeneous group of microorganisms that are currently attracting increased attention from scientists and industry. Numerous and diverse biological activities make them promising candidates for a wide range of applications not limited to the food sector. In addition to their major contribution to flavor development in fermented foods, their antagonistic activities toward undesirable bacteria, and fungi are now widely known. These activities are associated with their competitiveness for nutrients, acidification of their growth medium, their tolerance of high concentrations of ethanol, and release of antimicrobial compounds such as antifungal killer toxins or “mycocins” and antibacterial compounds. While the design of foods containing probiotics (microorganisms that confer health benefits) has focused primarily on Lactobacillus and Bifidobacterium, the yeast Saccharomyces cerevisiae var. boulardii has long been known effective for treating gastroenteritis. In this review, the antimicrobial activities of yeasts are examined. Mechanisms underlying this antagonistic activity as well as recent applications of these biologically active yeasts in both the medical and veterinary sectors are described. PMID:23267352

Comparison of different drying methods on the physical properties, bioactive compounds and antioxidant activity of raspberry powders.

PubMed

Si, Xu; Chen, Qinqin; Bi, Jinfeng; Wu, Xinye; Yi, Jianyong; Zhou, Linyan; Li, Zhaolu

2016-04-01

Dehydration has been considered as one of the traditional but most effective techniques for perishable fruits. Raspberry powders obtained after dehydration can be added as ingredients into food formulations such as bakery and dairy products. In this study, raspberry powders obtained by hot air drying (HAD), infrared radiation drying (IRD), hot air and explosion puffing drying (HA-EPD), infrared radiation and microwave vacuum drying (IR-MVD) and freeze drying (FD) were compared on physical properties, bioactive compounds and antioxidant activity. Drying techniques affected the physical properties, bioactive compounds and antioxidant activity of raspberry powders greatly. FD led to significantly higher (P < 0.05) values of water solubility (45.26%), soluble solid (63.46%), hygroscopicity (18.06%), color parameters and anthocyanin retention (60.70%) of raspberry powder compared with other drying methods. However, thermal drying techniques, especially combined drying methods, were superior to FD in final total polyphenol content, total flavonoid content and antioxidant activity. The combined drying methods, especially IR-MVD, showed the highest total polyphenol content (123.22 g GAE kg(-1) dw) and total flavonoid content (0.30 g CAE kg(-1) dw). Additionally, IR-MVD performed better in antioxidant activity retention. Overall, combined drying methods, especially IR-MVD, were found to result in better quality of raspberry powders among the thermal drying techniques. IR-MVD could be recommended for use in the drying industry because of its advantages in time saving and nutrient retention. © 2015 Society of Chemical Industry.

Chromatin and Transcription in Yeast

PubMed Central

Rando, Oliver J.; Winston, Fred

2012-01-01

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

Changes of hydrogen peroxide and radical-scavenging activity of raspberry during osmotic, convective, and freeze-drying.

PubMed

Novaković, Miroslav M; Stevanović, Snežana M; Gorjanović, Stanislava Ž; Jovanovic, Predrag M; Tešević, Vele V; Janković, Miodrag A; Sužnjević, Desanka Ž

2011-05-01

This study was conducted to investigate the influence of different drying treatments on antioxidant (AO) activity and phenolic content of raspberry (Rubus idaeus), cultivar Willamette. Whole raspberry fruits were dried convectively (air-drying), osmotically, and freeze-dried. Acetone-water extracts of fresh and dried raspberries were assessed for total phenolic content by standard Folin-Ciocalteau method. Two AO assays were applied, a recently developed direct current (DC) polarographic assay based on decrease of anodic oxidation current of hydrogen peroxide and widely used radical scavenge against the 1,1-diphenyl-2-picrylhydrazyl (DPPH). Strong correlation has been obtained between both AO assays and total phenolic content. In addition, some individual phenolic compounds present in raspberry have been assessed using DPPH and DC polarographic assay. Comparison and evaluation of drying methods has been based on preservation of AO activity and total phenolic content. Obtained results confirmed superiority of freeze-drying; convective drying caused slight changes while osmotic dehydration showed a significant decrease of phenolic compounds and AO activity. © 2011 Institute of Food Technologists®

Evaluation of Different Yeast Species for Improving In vitro Fermentation of Cereal Straws

PubMed Central

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

2016-01-01

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

Further studies on the quaternary structure of yeast casein kinase II.

PubMed

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

1986-01-01

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

Inactivation of bacterial quorum sensing signals N-acyl homoserine lactones is widespread in yeasts.

PubMed

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

2018-01-01

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

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

PubMed Central

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

2012-01-01

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

Microbial ecology of extreme environments: Antarctic yeasts and growth in substrate-limited habitats

NASA Technical Reports Server (NTRS)

Vishniac, H. S.

1985-01-01

The high, dry valleys of the Ross Desert of Antarctic, characterized by extremely low temperatures, aridity and a depauperate biota, are used as an analog of the postulated extreme climates of other planetary bodies of the Solar System to test the hypothesis that if life could be supported by Ross, it might be possible where similar conditions prevail. The previously considered sterility of the Ross Desert soil ecosystem has yielded up an indigenous yeast, Cryptoccus vishniacci, which is able to resist the extremes of cold, wet and dry freezing, and long arid periods, while making minimal nutritional demands on the soil.

A Comparison of the Beneficial Effects of Live and Heat-Inactivated Baker's Yeast on Nile Tilapia: Suggestions on the Role and Function of the Secretory Metabolites Released from the Yeast.

PubMed

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

2015-01-01

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

[In vitro activity of voriconazole against yeast and algae isolates according to new resistance pattern cut-off points].

PubMed

Pemán, J; Cantón, E; Calabuig, E; Bosch, M; Valentí, A; Viudes, A; Gobernado, M

2006-03-01

Voriconazole is a second-generation triazole derived from fluconazole but with greater potency and spectrum of activity, showing good in vitro activity against Candida, Cryptococcus and Aspergillus species, and other filamentous and dimorphic fungi. It can be administered orally or intravenously. It was initially approved in 2002 by the U.S. Food and Drug Administration as a treatment option for invasive aspergillosis and Fusarium and S. apiospermum infections showing resistance or intolerance to other antifungals; later on, it also received approval in the United States and Europe as a treatment option for esophageal candidiasis; candida infection in non-neutropenic patients; disseminated candidiasis of skin, abdomen, kidney and bladder; and injuries. Recently, the Clinical Laboratory Standard Institute established some provisional break points for voriconazole, classifying isolates with an MICor=4 mg/l as resistant. In line with these new data, we performed a systematic review of literature on in vitro activity of voriconazole against yeast and algae isolates, and compared it to that of fluconazole and itraconazole. The review included a total of 27,340 yeast isolates, 24,177 of Candida species, 2,726 of Cryptococcus species, 453 of other species, and 104 Prototheca. The yeast isolates resistant to voriconazole is approximately 1%, and 71% of fluconazole-resistant isolates are susceptible to voriconazole.

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

NASA Astrophysics Data System (ADS)

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

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

Screening of intact yeasts and cell extracts to reduce Scrapie prions during biotransformation of food waste.

PubMed

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.

Degradation of Biochemical Activity in Soil Sterilized by Dry Heat and Gamma Radiation

NASA Technical Reports Server (NTRS)

Shih, K. L.; Souza, K. A.

1978-01-01

The effect of soil sterilization by dry heat (0.08% relative humidity), gamma radiation, or both on soil phosphatase, urease, and decarboxylase activity was studied. Soil sterilized by a long exposure to dry heat at relatively low temperatures (eight weeks at 100.5 C) retained higher activities than did soil exposed to a higher temperature (two weeks at 124.5 C), while all activity was destroyed by four days at 148.5 C. Sterilization with 7.5 Mrads destroyed less activity than did heat sterilization. The effect of several individually nonsterizing doses of heat radiation is described.

Yeasts are essential for cocoa bean fermentation.

PubMed

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

2014-03-17

Cocoa beans (Theobroma cacao) are the major raw material for chocolate production and fermentation of the beans is essential for the development of chocolate flavor precursors. In this study, a novel approach was used to determine the role of yeasts in cocoa fermentation and their contribution to chocolate quality. Cocoa bean fermentations were conducted with the addition of 200ppm Natamycin to inhibit the growth of yeasts, and the resultant microbial ecology and metabolism, bean chemistry and chocolate quality were compared with those of normal (control) fermentations. The yeasts Hanseniaspora guilliermondii, Pichia kudriavzevii and Kluyveromyces marxianus, the lactic acid bacteria Lactobacillus plantarum and Lactobacillus fermentum and the acetic acid bacteria Acetobacter pasteurianus and Gluconobacter frateurii were the major species found in the control fermentation. In fermentations with the presence of Natamycin, the same bacterial species grew but yeast growth was inhibited. Physical and chemical analyses showed that beans fermented without yeasts had increased shell content, lower production of ethanol, higher alcohols and esters throughout fermentation and lesser presence of pyrazines in the roasted product. Quality tests revealed that beans fermented without yeasts were purplish-violet in color and not fully brown, and chocolate prepared from these beans tasted more acid and lacked characteristic chocolate flavor. Beans fermented with yeast growth were fully brown in color and gave chocolate with typical characters which were clearly preferred by sensory panels. Our findings demonstrate that yeast growth and activity were essential for cocoa bean fermentation and the development of chocolate characteristics. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

Effect of yeast culture and Aspergillus oryzae fermentation extract on ruminal characteristics and nutrient digestibility.

PubMed

Wiedmeier, R D; Arambel, M J; Walters, J L

1987-10-01

Four nonpregnant and nonlactating Holstein cows fitted with ruminal fistulas were assigned to each of four diets in a 4 X 4 Latin square design. Dietary treatments were 1) basal diet containing 50% concentrate; 2) basal diet plus 90 g/d yeast culture; 3) basal diet plus 2.63 g/d Aspergillus oryzae fermentation extract; 4) basal diet plus 90 g/d of A. oryzae fermentation extract and yeast culture. Cows were fed diets at a rate of 86 g DM/kg BW.75 for 14 d adaptation followed by an 8-d collection period. Digestibility of dry matter was increased by A. oryzae and A. oryzae and yeast culture combination treatments. Digestibility of CP was increased regardless of fungal culture addition. Hemicellulose digestibility, percent ruminal cellulolytic organisms, and acetate to propionate ratio were increased by the addition of fungal supplements.

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

PubMed

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.

Multiple determinants controlling activation of yeast replication origins late in S phase.

PubMed

Friedman, K L; Diller, J D; Ferguson, B M; Nyland, S V; Brewer, B J; Fangman, W L

1996-07-01

Analysis of a 131-kb segment of the left arm of yeast chromosome XIV beginning 157 kb from the telomere reveals four highly active origins of replication that initiate replication late in S phase. Previous work has shown that telomeres act as determinants for late origin activation. However, at least two of the chromosome XIV origins maintain their late activation time when located on large circular plasmids, indicating that late replication is independent of telomeres. Analysis of the replication time of plasmid derivatives containing varying amounts of chromosome XIV DNA show that a minimum of three chromosomal elements, distinct from each tested origin, contribute to late activation time. These late determinants are functionally equivalent, because duplication of one set of contributing sequences can compensate for the removal of another set. Furthermore, insertion of an origin that is normally early activated into this domain results in a shift to late activation, suggesting that the chromosome XIV origins are not unique in their ability to respond to the late determinants.

Antimicrobial activity of essential oils of Xylopia aethiopica.

PubMed

Fleischer, T C; Mensah, M L K; Mensah, A Y; Komlaga, G; Gbedema, S Y; Skaltsa, H

2008-06-18

Xylopia aethiopica is a medicinal plant of great repute in West Africa which produces a variety of complex chemical compounds. The fresh and dried fruits, leaf, stem bark and root bark essential oils showed various degrees of activity against the gram positive bacteria, Bacillus subtilis and Staphylococcus aureus, the gram negative bacteria Pseudomonas aeruginosa and the yeast-like fungus Candida albicans, using the cup plate method. However, none of the oils showed activity against Escherichia coli.

Effect of drying procedures on the physicochemical properties and antioxidant activities of polysaccharides from Crassostrea gigas

PubMed Central

Zheng, Yaxu; Qu, Min; Jin, Qiao; Tong, Changqing

2017-01-01

Crassostrea gigas polysaccharides (CGP) were obtained by different drying methods: freeze-drying (FD), spray-drying (SD) or rotary evaporation-drying (RED). The physicochemical properties of CGP were evaluated on the basis of polysaccharide content, protein content, color characteristics, FT-IR spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Antioxidant activities were researched three different free radicals, including DPPH free radicals, ABTS free radicals and reducing power. The results demonstrated that FDCGP, SDCGP and REDCGP have different physicochemical properties and antioxidant activities. Contrasted with FDCGP and REDCGP, SDCGP exhibited stronger antioxidant abilities. Therefore, considering the polysaccharides appearances and antioxidant activities, the spray drying method is a decent selection for the preparation of such polysaccharides, and it should be selected for application in the food industry. PMID:29176846

Effects of asparagine, fructose, and baking conditions on acrylamide content in yeast-leavened wheat bread.

PubMed

Surdyk, Nicolas; Rosén, Johan; Andersson, Roger; Aman, Per

2004-04-07

A repeatable procedure for studying the effects of internal and external factors on acrylamide content in yeast-leavened wheat bread has been developed. The dough contained wheat endosperm flour with a low content of precursors for acrylamide formation (asparagine and reducing sugars), dry yeast, salt, and water. The effects of asparagine and fructose, added to the dough, were studied in an experiment with a full factorial design. More than 99% of the acrylamide was found in the crust. Added asparagine dramatically increased the content of acrylamide in crusts dry matter (from about 80 microg/kg to between 600 and 6000 microg/kg) while added fructose did not influence the content. The effects of temperature and time of baking were studied in another experiment using a circumscribed central composite design. Mainly temperature (above 200 degrees C) but also time increased the acrylamide content in crust dry matter (from below 10 to 1900 microg/kg), and a significant interaction was found between these two factors. When baked at different conditions with the same ingredients, a highly significant relationship (P < 0.001) between color and acrylamide content in crust was found. Added asparagine, however, did not increase color, showing that mainly other amino compounds are involved in the browning reactions.

Isolation of baker's yeast mutants with proline accumulation that showed enhanced tolerance to baking-associated stresses.

PubMed

Tsolmonbaatar, Ariunzaya; Hashida, Keisuke; Sugimoto, Yukiko; Watanabe, Daisuke; Furukawa, Shuhei; Takagi, Hiroshi

2016-12-05

During bread-making processes, yeast cells are exposed to baking-associated stresses such as freeze-thaw, air-drying, and high-sucrose concentrations. Previously, we reported that self-cloning diploid baker's yeast strains that accumulate proline retained higher-level fermentation abilities in both frozen and sweet doughs than the wild-type strain. Although self-cloning yeasts do not have to be treated as genetically modified yeasts, the conventional methods for breeding baker's yeasts are more acceptable to consumers than the use of self-cloning yeasts. In this study, we isolated mutants resistant to the proline analogue azetidine-2-carboxylate (AZC) derived from diploid baker's yeast of Saccharomyces cerevisiae. Some of the mutants accumulated a greater amount of intracellular proline, and among them, 5 mutants showed higher cell viability than that observed in the parent wild-type strain under freezing or high-sucrose stress conditions. Two of them carried novel mutations in the PRO1 gene encoding the Pro247Ser or Glu415Lys variant of γ-glutamyl kinase (GK), which is a key enzyme in proline biosynthesis in S. cerevisiae. Interestingly, we found that these mutations resulted in AZC resistance of yeast cells and desensitization to proline feedback inhibition of GK, leading to intracellular proline accumulation. Moreover, baker's yeast cells expressing the PRO1 P247S and PRO1 E415K gene were more tolerant to freezing stress than cells expressing the wild-type PRO1 gene. The approach described here could be a practical method for the breeding of proline-accumulating baker's yeasts with higher tolerance to baking-associated stresses. Copyright © 2016 Elsevier B.V. All rights reserved.

Occurrence of killer yeasts in leaf-cutting ant nests.

PubMed

Carreiro, S C; Pagnocca, F C; Bacci, M; Bueno, O C; Hebling, M J A; Middelhoven, W J

2002-01-01

Killer activity was screened in 99 yeast strains isolated from the nests of the leaf-cutting ant Atta sexdens against 6 standard sensitive strains, as well as against each other. Among this yeast community killer activity was widespread since 77 strains (78%) were able to kill or inhibit the growth of at least one standard strain or nest strain. Toxin production was observed in representatives of all the studied genera including Aureobasidium, Rhodotorula, Tremella and Trichosporon, whose killer activity has not yet been described.

Kinetics, biocompounds, antioxidant activity, and sensory attributes of quinces as affected by drying method.

PubMed

Szychowski, Przemysław J; Lech, Krzysztof; Sendra-Nadal, Esther; Hernández, Francisca; Figiel, Adam; Wojdyło, Aneta; Carbonell-Barrachina, Ángel A

2018-07-30

Quinces are attracting interest due to their health and nutritional benefits. Drying kinetics, bioactive compounds, antioxidant activity, and the main sensory parameters were determined in dried quinces, cultivar Leskovač, as affected by the drying method. The highest total polyphenols content was observed in dried samples obtained after freeze drying and convective drying at 50 °C. The best drying treatment, considering only sensory attributes, was vacuum-microwave drying at 480 W, because it led to intermediate dark color and high intensities of basic tastes and key flavor attributes. The studied parameters were finally used to recommend convective drying at 60 °C as the most appropriate drying method for quinces, because it had a high content of total phenolic compounds (2nd best treatment out of 10), a good sensory profile, was cheap, and caused no negative effects on nutritional or sensory parameters; the only disadvantage was its long drying time. Copyright © 2018 Elsevier Ltd. All rights reserved.

Cell cycle entry triggers a switch between two modes of Cdc42 activation during yeast polarization

PubMed Central

Witte, Kristen; Strickland, Devin; Glotzer, Michael

2017-01-01

Cell polarization underlies many cellular and organismal functions. The GTPase Cdc42 orchestrates polarization in many contexts. In budding yeast, polarization is associated with a focus of Cdc42•GTP which is thought to self sustain by recruiting a complex containing Cla4, a Cdc42-binding effector, Bem1, a scaffold, and Cdc24, a Cdc42 GEF. Using optogenetics, we probe yeast polarization and find that local recruitment of Cdc24 or Bem1 is sufficient to induce polarization by triggering self-sustaining Cdc42 activity. However, the response to these perturbations depends on the recruited molecule, the cell cycle stage, and existing polarization sites. Before cell cycle entry, recruitment of Cdc24, but not Bem1, induces a metastable pool of Cdc42 that is sustained by positive feedback. Upon Cdk1 activation, recruitment of either Cdc24 or Bem1 creates a stable site of polarization that induces budding and inhibits formation of competing sites. Local perturbations have therefore revealed unexpected features of polarity establishment. DOI: http://dx.doi.org/10.7554/eLife.26722.001 PMID:28682236

Thionin-like peptides from Capsicum annuum fruits with high activity against human pathogenic bacteria and yeasts.

PubMed

Taveira, Gabriel B; Mathias, Luciana S; da Motta, Olney V; Machado, Olga L T; Rodrigues, Rosana; Carvalho, André O; Teixeira-Ferreira, André; Perales, Jonas; Vasconcelos, Ilka M; Gomes, Valdirene M

2014-01-01

Plants defend themselves against pathogens with production of antimicrobial peptides (AMPs). Herein we describe the discovery of a new antifungal and antibacterial peptide from fruits of Capsicum annuum that showed similarity to an already well characterized family of plant AMPs, thionins. Other fraction composed of two peptides, in which the major peptide also showed similarity to thionins. Among the obtained fractions, fraction 1, which is composed of a single peptide of 7 kDa, was sequenced by Edman method and its comparative sequence analysis in database (nr) showed similarity to thionin-like peptides. Tests against microorganisms, fraction 1 presented inhibitory activity to the cells of yeast Saccharomyces cerevisiae, Candida albicans, and Candida tropicalis and caused growth reduction to the bacteria species Escherichia coli and Pseudomonas aeruginosa. Fraction 3 caused inhibitory activity only for C. albicans and C. tropicalis. This fraction was composed of two peptides of ∼7 and 10 kDa, and the main protein band correspondent to the 7 kDa peptide, also showed similarity to thionins. This plasma membrane permeabilization assay demonstrates that the peptides present in the fractions 1 and 3 induced changes in the membranes of all yeast strains, leading to their permeabilization. Fraction 1 was capable of inhibiting acidification of the medium of glucose-induced S. cerevisiae cells 78% after an incubation time of 30 min, and opposite result was obtained for C. albicans. Experiments demonstrate that the fraction 1 and 3 were toxic and induced changes in the membranes of all yeast strains, leading to their permeabilization. Copyright © 2013 Wiley Periodicals, Inc.

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

PubMed Central

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

2017-01-01

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

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

PubMed

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

2017-01-02

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

Prions in Yeast

PubMed Central

Liebman, Susan W.; Chernoff, Yury O.

2012-01-01

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

Structural variants of yeast prions show conformer-specific requirements for chaperone activity

PubMed Central

Stein, Kevin C.; True, Heather L.

2016-01-01

Summary Molecular chaperones monitor protein homeostasis and defend against the misfolding and aggregation of proteins that is associated with protein conformational disorders. In these diseases, a variety of different aggregate structures can form. These are called prion strains, or variants, in prion diseases, and cause variation in disease pathogenesis. Here, we use variants of the yeast prions [RNQ+] and [PSI+] to explore the interactions of chaperones with distinct aggregate structures. We found that prion variants show striking variation in their relationship with Hsp40s. Specifically, the yeast Hsp40 Sis1, and its human ortholog Hdj1, had differential capacities to process prion variants, suggesting that Hsp40 selectivity has likely changed through evolution. We further show that such selectivity involves different domains of Sis1, with some prion conformers having a greater dependence on particular Hsp40 domains. Moreover, [PSI+] variants were more sensitive to certain alterations in Hsp70 activity as compared to [RNQ+] variants. Collectively, our data indicate that distinct chaperone machinery is required, or has differential capacity, to process different aggregate structures. Elucidating the intricacies of chaperone-client interactions, and how these are altered by particular client structures, will be crucial to understanding how this system can go awry in disease and contribute to pathological variation. PMID:25060529

Arsenic Directly Binds to and Activates the Yeast AP-1-Like Transcription Factor Yap8

PubMed Central

Kumar, Nallani Vijay; Yang, Jianbo; Pillai, Jitesh K.; Rawat, Swati; Solano, Carlos; Kumar, Abhay; Grøtli, Morten; Stemmler, Timothy L.; Rosen, Barry P.

2015-01-01

The AP-1-like transcription factor Yap8 is critical for arsenic tolerance in the yeast Saccharomyces cerevisiae. However, the mechanism by which Yap8 senses the presence of arsenic and activates transcription of detoxification genes is unknown. Here we demonstrate that Yap8 directly binds to trivalent arsenite [As(III)] in vitro and in vivo and that approximately one As(III) molecule is bound per molecule of Yap8. As(III) is coordinated by three sulfur atoms in purified Yap8, and our genetic and biochemical data identify the cysteine residues that form the binding site as Cys132, Cys137, and Cys274. As(III) binding by Yap8 does not require an additional yeast protein, and Yap8 is regulated neither at the level of localization nor at the level of DNA binding. Instead, our data are consistent with a model in which a DNA-bound form of Yap8 acts directly as an As(III) sensor. Binding of As(III) to Yap8 triggers a conformational change that in turn brings about a transcriptional response. Thus, As(III) binding to Yap8 acts as a molecular switch that converts inactive Yap8 into an active transcriptional regulator. This is the first report to demonstrate how a eukaryotic protein couples arsenic sensing to transcriptional activation. PMID:26711267

Arsenic Directly Binds to and Activates the Yeast AP-1-Like Transcription Factor Yap8

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

Kumar, Nallani Vijay; Yang, Jianbo; Pillai, Jitesh K.

The AP-1-like transcription factor Yap8 is critical for arsenic tolerance in the yeastSaccharomyces cerevisiae. However, the mechanism by which Yap8 senses the presence of arsenic and activates transcription of detoxification genes is unknown. Here we demonstrate that Yap8 directly binds to trivalent arsenite [As(III)]in vitroandin vivoand that approximately one As(III) molecule is bound per molecule of Yap8. As(III) is coordinated by three sulfur atoms in purified Yap8, and our genetic and biochemical data identify the cysteine residues that form the binding site as Cys132, Cys137, and Cys274. As(III) binding by Yap8 does not require an additional yeast protein, and Yap8more » is regulated neither at the level of localization nor at the level of DNA binding. Instead, our data are consistent with a model in which a DNA-bound form of Yap8 acts directly as an As(III) sensor. Binding of As(III) to Yap8 triggers a conformational change that in turn brings about a transcriptional response. Thus, As(III) binding to Yap8 acts as a molecular switch that converts inactive Yap8 into an active transcriptional regulator. This is the first report to demonstrate how a eukaryotic protein couples arsenic sensing to transcriptional activation.« less

Architecture of the Yeast RNA Polymerase II Open Complex and Regulation of Activity by TFIIF

PubMed Central

Fishburn, James

2012-01-01

To investigate the function and architecture of the open complex state of RNA polymerase II (Pol II), Saccharomyces cerevisiae minimal open complexes were assembled by using a series of heteroduplex HIS4 promoters, TATA binding protein (TBP), TFIIB, and Pol II. The yeast system demonstrates great flexibility in the position of active open complexes, spanning 30 to 80 bp downstream from TATA, consistent with the transcription start site scanning behavior of yeast Pol II. TFIIF unexpectedly modulates the activity of the open complexes, either repressing or stimulating initiation. The response to TFIIF was dependent on the sequence of the template strand within the single-stranded bubble. Mutations in the TFIIB reader and linker region, which were inactive on duplex DNA, were suppressed by the heteroduplex templates, showing that a major function of the TFIIB reader and linker is in the initiation or stabilization of single-stranded DNA. Probing of the architecture of the minimal open complexes with TFIIB-FeBABE [TFIIB–p-bromoacetamidobenzyl–EDTA-iron(III)] derivatives showed that the TFIIB core domain is surprisingly positioned away from Pol II, and the addition of TFIIF repositions the TFIIB core domain to the Pol II wall domain. Together, our results show an unexpected architecture of minimal open complexes and the regulation of activity by TFIIF and the TFIIB core domain. PMID:22025674

In Vitro Activities of Terbinafine against Cutaneous Isolates of Candida albicans and Other Pathogenic Yeasts

PubMed Central

Ryder, Neil S.; Wagner, Sonja; Leitner, Ingrid

1998-01-01

Terbinafine is active in vitro against a wide range of pathogenic fungi, including dermatophytes, molds, dimorphic fungi, and some yeasts, but earlier studies indicated that the drug had little activity against Candida albicans. In contrast, clinical studies have shown topical and oral terbinafine to be active in cutaneous candidiasis and Candida nail infections. In order to define the anti-Candida activity of terbinafine, we tested the drug against 350 fresh clinical isolates and additional strains by using a broth dilution assay standardized according to the guidelines of the National Committee for Clinical Laboratory Standards (NCCLS) M27-A assay. Terbinafine was found to have an MIC of 1 μg/ml for reference C. albicans strains. For 259 clinical isolates, the MIC at which 50% of the isolates are inhibited (MIC50) of terbinafine was 1 μg/ml (fluconazole, 0.5 μg/ml), and the MIC90 was 4 μg/ml (fluconazole, 1 μg/ml). Terbinafine was highly active against Candida parapsilosis (MIC90, 0.125 μg/ml) and showed potentially interesting activity against isolates of Candida dubliniensis, Candida guilliermondii, Candida humicola, and Candida lusitaniae. It was not active against the Candida glabrata, Candida krusei, and Candida tropicalis isolates in this assay. Cryptococcus laurentii and Cryptococcus neoformans were highly susceptible to terbinafine, with MICs of 0.06 to 0.25 μg/ml. The NCCLS macrodilution assay provides reproducible in vitro data for terbinafine against Candida and other yeasts. The MICs for C. albicans and C. parapsilosis are compatible with the known clinical efficacy of terbinafine in cutaneous infections, while the clinical relevance of its activities against the other species has yet to be determined. PMID:9593126

Characterization of Inulin Hydrolyzing Enzyme(s) in Oleaginous Yeast Trichosporon cutaneum in Consolidated Bioprocessing of Microbial Lipid Fermentation.

PubMed

Wang, Juan; Zhang, Huizhan; Bao, Jie

2015-11-01

Oleaginous yeast Trichosporon cutaneum CGMCC 2.1374 was found to utilize inulin directly for microbial lipid fermentation without a hydrolysis step. The potential inulinase-like enzyme(s) in T. cutaneum CGMCC 2.1374 were characterized and compared with other inulinase enzymes produced by varied yeast strains. The consolidated bioprocessing (CBP) for lipid accumulated using inulin was optimized with 4.79 g/L of lipid produced from 50 g/L inulin with the lipid content of 33.6% in dry cells. The molecular weight of the enzyme was measured which was close to invertase in Saccharomyces cerevisiae. The study provided information for inulin hydrolyzing enzyme(s) in oleaginous yeasts, as well as a preliminary CBP process for lipid production from inulin feedstock.

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

PubMed

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.

Anethole potentiates dodecanol's fungicidal activity by reducing PDR5 expression in budding yeast.

PubMed

Fujita, Ken-Ichi; Ishikura, Takayuki; Jono, Yui; Yamaguchi, Yoshihiro; Ogita, Akira; Kubo, Isao; Tanaka, Toshio

2017-02-01

trans-Anethole (anethole), a major component of anise oil, has a broad antimicrobial spectrum and a weaker antimicrobial potency than other available antibiotics. When combined with polygodial, nagilactone E, and n-dodecanol, anethole has been shown to exhibit synergistic antifungal activity against a budding yeast, Saccharomyces cerevisiae, and a human opportunistic pathogenic yeast, Candida albicans. However, the mechanism underlying this synergistic effect of anethole has not been characterized. We studied this mechanism using dodecanol-treated S. cerevisiae cells and focusing on genes related to multidrug efflux. Although dodecanol transiently reduced the number of colony forming units, this recovered to levels similar to those of untreated cells with continued incubation beyond 24h. Reverse transcription polymerase chain reaction analysis revealed overexpression of an ATP-binding cassette (ABC) transporter gene, PDR5, in addition to a slight increase in PDR11, PDR12, and PDR15 transcriptions in dodecanol-treated cells. In the presence of anethole, these effects were attenuated and the fungicidal activity of dodecanol was extended. Dodecanol showed longer lasting fungicidal activity against a Δpdr5. In addition, Δpdr3 and Δlge1, lack transcription factors of PDR5 and PDR3, were partly and completely susceptible to dodecanol, respectively. Furthermore, combination of anethole with fluconazole was also found to exhibit synergy on C. albicans. These results indicated that although anethole reduced the transcription of several transporters, PDR5 expression was particularly relevant to dodecanol efflux. Anethole is expected to be a promising candidate drug for the inhibition of efflux by reducing the transcription of several ABC transporters. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of new Torulaspora delbrueckii killer yeasts on the must fermentation kinetics and aroma compounds of white table wine

PubMed Central

Velázquez, Rocío; Zamora, Emiliano; Álvarez, María L.; Hernández, Luis M.; Ramírez, Manuel

2015-01-01

Torulaspora delbrueckii is becoming widely recommended for improving some specific characteristics of wines. However, its impact on wine quality is still far from satisfactory at the winery level, mostly because it is easily replaced by Saccharomyces cerevisiae-like yeasts during must fermentation. New T. delbrueckii killer strains were here isolated and selected for winemaking. They killed S. cerevisiae yeasts and were able to dominate and complete the fermentation of sterile grape must. Sequential yeast inoculation of non-sterile white must with T. delbrueckii followed by S. cerevisiae did not ensure T. delbrueckii dominance or wine quality improvement. Only a single initial must inoculation at high cell concentrations allowed the T. delbrueckii killer strains to dominate and complete the must fermentation to reach above 11% ethanol, but not the non-killer strains. None of the wines underwent malolactic fermentation as long as the must had low turbidity and pH. Although no statistically significant differences were found in the wine quality score, the S. cerevisiae-dominated wines were preferred over the T. delbrueckii-dominated ones because the former had high-intensity fresh fruit aromas while the latter had lower intensity, but nevertheless nice and unusual dried fruit/pastry aromas. Except for ethyl propanoate and 3-ethoxy-1-propanol, which were more abundant in the T. delbrueckii–dominated wines, most of the compounds with fresh fruit odor descriptors, including those with the greatest odor activity values (isoamyl acetate, ethyl hexanoate, and ethyl octanoate), were more abundant in the S. cerevisiae–dominated wines. The low relative concentrations of these fruity compounds made it possible to detect in the T. delbrueckii–dominated wines the low-relative-concentration compounds with dried fruit and pastry odors. An example was γ-ethoxy-butyrolactone which was significantly more abundant in these wines than in those dominated by S. cerevisiae. PMID

Effects of new Torulaspora delbrueckii killer yeasts on the must fermentation kinetics and aroma compounds of white table wine.

PubMed

Velázquez, Rocío; Zamora, Emiliano; Álvarez, María L; Hernández, Luis M; Ramírez, Manuel

2015-01-01

Torulaspora delbrueckii is becoming widely recommended for improving some specific characteristics of wines. However, its impact on wine quality is still far from satisfactory at the winery level, mostly because it is easily replaced by Saccharomyces cerevisiae-like yeasts during must fermentation. New T. delbrueckii killer strains were here isolated and selected for winemaking. They killed S. cerevisiae yeasts and were able to dominate and complete the fermentation of sterile grape must. Sequential yeast inoculation of non-sterile white must with T. delbrueckii followed by S. cerevisiae did not ensure T. delbrueckii dominance or wine quality improvement. Only a single initial must inoculation at high cell concentrations allowed the T. delbrueckii killer strains to dominate and complete the must fermentation to reach above 11% ethanol, but not the non-killer strains. None of the wines underwent malolactic fermentation as long as the must had low turbidity and pH. Although no statistically significant differences were found in the wine quality score, the S. cerevisiae-dominated wines were preferred over the T. delbrueckii-dominated ones because the former had high-intensity fresh fruit aromas while the latter had lower intensity, but nevertheless nice and unusual dried fruit/pastry aromas. Except for ethyl propanoate and 3-ethoxy-1-propanol, which were more abundant in the T. delbrueckii-dominated wines, most of the compounds with fresh fruit odor descriptors, including those with the greatest odor activity values (isoamyl acetate, ethyl hexanoate, and ethyl octanoate), were more abundant in the S. cerevisiae-dominated wines. The low relative concentrations of these fruity compounds made it possible to detect in the T. delbrueckii-dominated wines the low-relative-concentration compounds with dried fruit and pastry odors. An example was γ-ethoxy-butyrolactone which was significantly more abundant in these wines than in those dominated by S. cerevisiae.

Humanlike substitutions to Ω-loop D of yeast iso-1-cytochrome c only modestly affect dynamics and peroxidase activity.

PubMed

Lei, Haotian; Bowler, Bruce E

2018-06-01

Structural studies of yeast iso-1-cytochrome c (L.J. McClelland, T.-C. Mou, M.E. Jeakins-Cooley, S.R. Sprang, B.E. Bowler, Proc. Natl. Acad. Sci. U.S.A. 111 (2014) 6648-6653) show that modest movement of Ω-loop D (residues 70-85, average RMSD versus the native structure: 0.81 Å) permits loss of Met80-heme ligation creating an available coordination site to catalyze the peroxidase activity mediated by cytochrome c early in apoptosis. However, Ala81 and Gly83 move significantly (RMSDs of 2.18 and 1.26 Å, respectively). Ala81 and Gly83 evolve to Ile and Val, respectively, in human cytochrome c and peroxidase activity decreases 25-fold relative to the yeast protein at pH 7. To test the hypothesis that these residues evolved to restrict the peroxidase activity of cytochrome c, A81I and G83V variants of yeast iso-1-cytochrome c were prepared. For both variants, the apparent pK a of the alkaline transition increases by 0.2 to 0.3 relative to the wild type (WT) protein and the rate of opening the heme crevice is slowed. The cooperativity of acid unfolding is decreased for the G83V variant. At pH 7 and 8, the catalytic rate constant, k cat , for the peroxidase activity of both variants decreases relative to WT, consistent with the effects on alkaline isomerization. Below pH 7, the loss in the cooperativity of acid unfolding causes k cat for peroxidase activity to increase for the G83V variant relative to WT. Neither variant decreases k cat to the level of the human protein, indicating that other residues also contribute to the low peroxidase activity of human cytochrome c. Copyright © 2018 Elsevier Inc. All rights reserved.

Polyphenolic substrates and dyes degradation by yeasts from 25 de Mayo/King George Island (Antarctica).

PubMed

Rovati, José I; Pajot, Hipólito F; Ruberto, Lucas; Mac Cormack, Walter; Figueroa, Lucía I C

2013-11-01

Antarctica offers a range of extreme climatic conditions, such as low temperatures, high solar radiation and low nutrient availability, and constitutes one of the harshest environments on Earth. Despite that, it has been successfully colonized by ’cold-loving’ fungi, which play a key role in decomposition cycles in cold ecosystems. However, knowledge about the ecological role of yeasts in nutrient or organic matter recycling/mineralization remains highly fragmentary. The aim of this work was to study the yeast microbiota in samples collected on 25 de Mayo/King George Island regarding the scope of their ability to degrade polyphenolic substrates such as lignin and azo dyes. Sixty-one yeast isolates were obtained from 37 samples, including soil, rocks, wood and bones. Molecular analyses based on rDNA sequences revealed that 35 yeasts could be identified at the species level and could be classified in the genera Leucosporidiella, Rhodotorula, Cryptococcus, Bullera and Candida. Cryptococcus victoriae was by far the most ubiquitous species. In total, 33% of the yeast isolates examined showed significant activity for dye decolorization, 25% for laccase activity and 38% for ligninolytic activity. Eleven yeasts did not show positive activity in any of the assays performed and no isolates showed positive activity across all tested substrates. A high diversity of yeasts were isolated in this work, possibly including undescribed species and conspicuous Antarctic yeasts, most of them belonging to oligotrophic, slow-growing and metabolically diverse basidiomycetous genera.

TORC1 activity is partially reduced under nitrogen starvation conditions in sake yeast Kyokai no. 7, Saccharomyces cerevisiae.

PubMed

Nakazawa, Nobushige; Sato, Aya; Hosaka, Masahiro

2016-03-01

Industrial yeasts are generally unable to sporulate but treatment with the immunosuppressive drug rapamycin restores this ability in a sake yeast strain Kyokai no. 7 (K7), Saccharomyces cerevisiae. This finding suggests that TORC1 is active under sporulation conditions. Here, using a reporter gene assay, Northern and Western blots, we tried to gain insight into how TORC1 function under nitrogen starvation conditions in K7 cells. Similarly to a laboratory strain, RPS26A transcription was repressed and Npr1 was dephosphorylated in K7 cells, indicative of the expected loss of TORC1 function under nitrogen starvation. The expression of nitrogen catabolite repression-sensitive genes, however, was not induced, the level of Cln3 remained constant, and autophagy was more slowly induced than in a laboratory strain, all suggestive of active TORC1. We conclude that TORC1 activity is partially reduced under nitrogen starvation conditions in K7 cells. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Characterization of butter spoiling yeasts and their inhibition by some spices.

PubMed

Sagdic, Osman; Ozturk, Ismet; Bayram, Okan; Kesmen, Zulal; Yilmaz, Mustafa Tahsin

2010-01-01

This study was designed to identify the yeasts in packaged and unpackaged butters and screen antiyeast activity of spices, including marjoram (Origanum majorana L.), summer savory (Satureja hortensis L.), and black cumin (Nigella sativa L.) against the most dominant yeast species in the packaged and unpackaged butters. Mean total yeast populations were 5.40 log CFU/g in unpackaged butter samples and 2.22 log CFU/g in packaged butter samples, indicating better hygienic quality of packaged samples. Forty-nine yeast species were isolated and identified from butter samples with the most prevalent isolates belonging to genera Candida-C. kefyr, C. zeylanoides, and C. lambica-and with moderate number of isolates belonging to genera Cryptococcus, Rhodotorula, Saccharomyces, and Zygosaccharomyces. Black cumin exhibited the highest antiyeast activity against C. zeylanoides and C. lambica species, even inhibited these species, while summer savory inhibited C. kefyr. The results of this study revealed clear antimicrobial potential of black cumin against the yeast species isolated from butters. Marjoram, summer savory, and black cumin could be used as natural antimicrobial agents against spoilage yeasts in food preservation, especially in butter. © 2010 Institute of Food Technologists®

Characterization of Hyaluronan-Degrading Enzymes from Yeasts.

PubMed

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

2015-10-01

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

An Evolutionary Perspective on Yeast Mating-Type Switching

PubMed Central

Hanson, Sara J.; Wolfe, Kenneth H.

2017-01-01

Cell differentiation in yeast species is controlled by a reversible, programmed DNA-rearrangement process called mating-type switching. Switching is achieved by two functionally similar but structurally distinct processes in the budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe. In both species, haploid cells possess one active and two silent copies of the mating-type locus (a three-cassette structure), the active locus is cleaved, and synthesis-dependent strand annealing is used to replace it with a copy of a silent locus encoding the opposite mating-type information. Each species has its own set of components responsible for regulating these processes. In this review, we summarize knowledge about the function and evolution of mating-type switching components in these species, including mechanisms of heterochromatin formation, MAT locus cleavage, donor bias, lineage tracking, and environmental regulation of switching. We compare switching in these well-studied species to others such as Kluyveromyces lactis and the methylotrophic yeasts Ogataea polymorpha and Komagataella phaffii. We focus on some key questions: Which cells switch mating type? What molecular apparatus is required for switching? Where did it come from? And what is the evolutionary purpose of switching? PMID:28476860

Drying effect on flavonoid composition and antioxidant activity of immature kumquat.

PubMed

Lou, Shyi-Neng; Lai, Yi-Chun; Huang, Jia-De; Ho, Chi-Tang; Ferng, Lin-Huei A; Chang, Yung-Chung

2015-03-15

A seven flavonoids in hot water extract of immature kumquat (Citrus japonica var. margarita) were identified and quantified (mg/100g fresh fruit): 3',5'-di-C-β-glucopyranosylphloretin (DGPP, 285.9 ± 2.9 mg/100g), acacetin 8-C-neohesperidoside (margaritene, 136.2 ± 2.6 mg/100g), acacetin 6-C-neohesperidoside (isomargaritene, 119.1 ± 1.8 mg/100g), fortunellin (acacetin 7-O-neohesperidoside, 28.5 ± 0.7 mg/100g), apigenin 8-C-neohesperidoside (16.9 ± 0.1mg/100g), poncirin (isosakuranetin 7-O-neohesperidoside, 5.1 ± 0.1mg/100g), and rhoifolin (apigenin 7-O-neohesperidoside, 2.0 ± 0.1mg/100g). When immature kumquat was dried at 110 and 130°C for 0.5h, the antioxidant activity, total phenolic content and identified flavonoids increased. The UV absorbance of browning products of immature kumquat dried at 130°C for 1.5h increased dramatically, while the identified flavonoids decreased. Therefore, it was concluded that drying below 130°C for 1.0 h, could release phenolic compounds, which resulted in the increasing antioxidant activity. Drying at 130°C for 1.5h, it might be due to the effect of formed browning products. Copyright © 2014 Elsevier Ltd. All rights reserved.

L-arabinose fermenting yeast

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

Zhang, Min; Singh, Arjun; Suominen, Pirkko

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

L-arabinose fermenting yeast

DOEpatents

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

2014-09-23

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

A Comparison of the Beneficial Effects of Live and Heat-Inactivated Baker’s Yeast on Nile Tilapia: Suggestions on the Role and Function of the Secretory Metabolites Released from the Yeast

PubMed Central

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

2015-01-01

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

Activities of Tricarboxylic Acid Cycle Enzymes, Glyoxylate Cycle Enzymes, and Fructose Diphosphatase in Bakers' Yeast During Adaptation to Acetate Oxidation

PubMed Central

Gosling, J. P.; Duggan, P. F.

1971-01-01

Bakers' yeast oxidizes acetate at a high rate only after an adaptation period during which the capacity of the glyoxylate cycle is found to increase. There was apparently no necessity for the activity of acetyl-coenzyme A synthetase, the capacity of the tricarboxylic acid cycle, or the concentrations of the cytochromes to increase for this adaptation to occur. Elevation of fructose 1,6 diphosphatase occurred only when acetate oxidation was nearly maximal. Cycloheximide almost completely inhibited adaptation as well as increases in the activities of isocitrate lyase and aconitate hydratase, the only enzymes assayed. p-Fluorophenylalanine was partially effective and chloramphenicol did not inhibit at all. The presence of ammonium, which considerably delayed adaptation of the yeast to acetate oxidation, inhibited the increases in the activities of the glyoxylate cycle enzymes to different degrees, demonstrating noncoordinate control of these enzymes. Under the various conditions, the only enzyme activity increase consistently related to the rising oxygen uptake rate was that of isocitrate lyase which apparently limited the activity of the cycle. PMID:5557595

Deteriorated Stress Response in Stationary-Phase Yeast: Sir2 and Yap1 Are Essential for Hsf1 Activation by Heat Shock and Oxidative Stress, Respectively

PubMed Central

Cohen, Aviv; Bar-Nun, Shoshana

2014-01-01

Stationary-phase cultures have been used as an important model of aging, a complex process involving multiple pathways and signaling networks. However, the molecular processes underlying stress response of non-dividing cells are poorly understood, although deteriorated stress response is one of the hallmarks of aging. The budding yeast Saccharomyces cerevisiae is a valuable model organism to study the genetics of aging, because yeast ages within days and are amenable to genetic manipulations. As a unicellular organism, yeast has evolved robust systems to respond to environmental challenges. This response is orchestrated largely by the conserved transcription factor Hsf1, which in S. cerevisiae regulates expression of multiple genes in response to diverse stresses. Here we demonstrate that Hsf1 response to heat shock and oxidative stress deteriorates during yeast transition from exponential growth to stationary-phase, whereas Hsf1 activation by glucose starvation is maintained. Overexpressing Hsf1 does not significantly improve heat shock response, indicating that Hsf1 dwindling is not the major cause for Hsf1 attenuated response in stationary-phase yeast. Rather, factors that participate in Hsf1 activation appear to be compromised. We uncover two factors, Yap1 and Sir2, which discretely function in Hsf1 activation by oxidative stress and heat shock. In Δyap1 mutant, Hsf1 does not respond to oxidative stress, while in Δsir2 mutant, Hsf1 does not respond to heat shock. Moreover, excess Sir2 mimics the heat shock response. This role of the NAD+-dependent Sir2 is supported by our finding that supplementing NAD+ precursors improves Hsf1 heat shock response in stationary-phase yeast, especially when combined with expression of excess Sir2. Finally, the combination of excess Hsf1, excess Sir2 and NAD+ precursors rejuvenates the heat shock response. PMID:25356557

Deteriorated stress response in stationary-phase yeast: Sir2 and Yap1 are essential for Hsf1 activation by heat shock and oxidative stress, respectively.

PubMed

Nussbaum, Inbal; Weindling, Esther; Jubran, Ritta; Cohen, Aviv; Bar-Nun, Shoshana

2014-01-01

Stationary-phase cultures have been used as an important model of aging, a complex process involving multiple pathways and signaling networks. However, the molecular processes underlying stress response of non-dividing cells are poorly understood, although deteriorated stress response is one of the hallmarks of aging. The budding yeast Saccharomyces cerevisiae is a valuable model organism to study the genetics of aging, because yeast ages within days and are amenable to genetic manipulations. As a unicellular organism, yeast has evolved robust systems to respond to environmental challenges. This response is orchestrated largely by the conserved transcription factor Hsf1, which in S. cerevisiae regulates expression of multiple genes in response to diverse stresses. Here we demonstrate that Hsf1 response to heat shock and oxidative stress deteriorates during yeast transition from exponential growth to stationary-phase, whereas Hsf1 activation by glucose starvation is maintained. Overexpressing Hsf1 does not significantly improve heat shock response, indicating that Hsf1 dwindling is not the major cause for Hsf1 attenuated response in stationary-phase yeast. Rather, factors that participate in Hsf1 activation appear to be compromised. We uncover two factors, Yap1 and Sir2, which discretely function in Hsf1 activation by oxidative stress and heat shock. In Δyap1 mutant, Hsf1 does not respond to oxidative stress, while in Δsir2 mutant, Hsf1 does not respond to heat shock. Moreover, excess Sir2 mimics the heat shock response. This role of the NAD+-dependent Sir2 is supported by our finding that supplementing NAD+ precursors improves Hsf1 heat shock response in stationary-phase yeast, especially when combined with expression of excess Sir2. Finally, the combination of excess Hsf1, excess Sir2 and NAD+ precursors rejuvenates the heat shock response.

Effective moisture diffusivity and activation energy of rambutan seed under different drying methods to promote storage stability

NASA Astrophysics Data System (ADS)

Ahmad, So'bah; Shamsul Anuar, Mohd; Saleena Taip, Farah; Shamsudin, Rosnah; M, Siti Roha A.

2017-05-01

The effects of two drying methods, oven and microwave drying on the effective moisture diffusivity and activation energy of rambutan seed were studied. Effective moisture diffusivity and activation energy are the main indicators used for moisture movement within the material. Hence, it is beneficial to determine an appropriate drying method to attain a final moisture content of rambutan seed that potentially could be used as secondary sources in the industry. An appropriate final moisture content will provide better storage stability that can extend the lifespan of the rambutan seed. The rambutan seeds were dried with two drying methods (oven and microwave) at two level of the process variables (oven temperature; 40°C and 60°C and microwave power; 250W and 1000W) at constant initial moisture contents. The result showed that a higher value of effective moisture diffusivity and less activation energy were observed in microwave drying compared to oven drying. This finding portrays microwave drying expedites the moisture removal to achieve the required final moisture content and the most appropriate drying method for longer storage stability for rambutan seed. With respect to the process variables; higher oven temperatures and lower microwave powers also exhibit similar trends. Hopefully, this study would provide a baseline data to determine an appropriate drying method for longer storage period for turning waste to by-products.

Reduction of acrylamide in whole-wheat bread by combining lactobacilli and yeast fermentation.

PubMed

Nasiri Esfahani, Behnaz; Kadivar, Mahdi; Shahedi, Mohammad; Soleimanian-Zad, Sabihe

2017-11-01

This study mainly focuses on a strategy for reducing acrylamide content in whole-wheat bread by combining lactobacilli and yeast in sourdough breadmaking. Combinations of sourdough (fermented dough using different Lactobacillus strains including Lactobacillus plantarum PTCC 1896 [probiotic], L. sakei DSM 20,017, L. rhamnosus DSM 20,021, and L. delbrueckii DSM 20,081) and yeast, in comparison with yeast alone, were used for breadmaking. The results showed that acrylamide levels in breads fermented using sourdough+yeast were in all cases much lower (6.9-20 μg/kg on a dry weight basis [d.b.]) than those in the yeast-only fermented bread (47.6 μg/kg d.b.). Significant (p < 0.05) correlations were also found between pH, total titratable acids (TTA) and lactic acid, and acrylamide content. Furthermore, the obtained results showed that the moisture content of dough directly influenced the formation of acrylamide in bread (r = 0.925, p < 0.0001). In addition, no significant correlations were observed between acrylamide content in breads and either the reducing sugar or free amino acid contents in dough samples. According to the different effects of Lactobacillus strains, it could be concluded that the acrylamide reducing potential of lactobacilli was strain-specific, with L. rhamnosus being the most effective. This suggests that sourdough fermentation with appropriate Lactobacillus strains can be used as an advantageous technology to reduce the acrylamide content of whole-wheat breads.

MAP kinase pathways in the yeast Saccharomyces cerevisiae

NASA Technical Reports Server (NTRS)

Gustin, M. C.; Albertyn, J.; Alexander, M.; Davenport, K.; McIntire, L. V. (Principal Investigator)

1998-01-01

A cascade of three protein kinases known as a mitogen-activated protein kinase (MAPK) cascade is commonly found as part of the signaling pathways in eukaryotic cells. Almost two decades of genetic and biochemical experimentation plus the recently completed DNA sequence of the Saccharomyces cerevisiae genome have revealed just five functionally distinct MAPK cascades in this yeast. Sexual conjugation, cell growth, and adaptation to stress, for example, all require MAPK-mediated cellular responses. A primary function of these cascades appears to be the regulation of gene expression in response to extracellular signals or as part of specific developmental processes. In addition, the MAPK cascades often appear to regulate the cell cycle and vice versa. Despite the success of the gene hunter era in revealing these pathways, there are still many significant gaps in our knowledge of the molecular mechanisms for activation of these cascades and how the cascades regulate cell function. For example, comparison of different yeast signaling pathways reveals a surprising variety of different types of upstream signaling proteins that function to activate a MAPK cascade, yet how the upstream proteins actually activate the cascade remains unclear. We also know that the yeast MAPK pathways regulate each other and interact with other signaling pathways to produce a coordinated pattern of gene expression, but the molecular mechanisms of this cross talk are poorly understood. This review is therefore an attempt to present the current knowledge of MAPK pathways in yeast and some directions for future research in this area.

GC-Rich DNA Elements Enable Replication Origin Activity in the Methylotrophic Yeast Pichia pastoris

PubMed Central

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

2014-01-01

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

GC-rich DNA elements enable replication origin activity in the methylotrophic yeast Pichia pastoris.

PubMed

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

2014-03-01

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

Control activity of yeast geranylgeranyl diphosphate synthase from dimer interface through H-bonds and hydrophobic interaction.

PubMed

Chang, Chih-Kang; Teng, Kuo-Hsun; Lin, Sheng-Wei; Chang, Tao-Hsin; Liang, Po-Huang

2013-04-23

Previously we showed that yeast geranylgeranyl diphosphate synthase (GGPPS) becomes an inactive monomer when the first N-terminal helix involved in dimerization is deleted. This raises questions regarding why dimerization is required for GGPPS activity and which amino acids in the dimer interface are essential for dimerization-mediated activity. According to the GGPPS crystal structure, three amino acids (N101, N104, and Y105) located in the helix F of one subunit are near the active site of the other subunit. As presented here, when these residues were replaced individually with Ala caused insignificant activity changes, N101A/Y105A and N101A/N104A but not N104A/Y105A showed remarkably decreased k(cat) values (200-250-fold). The triple mutant N101A/N104A/Y105A displayed no detectable activity, although dimer was retained in these mutants. Because N101 and Y105 form H-bonds with H139 and R140 in the other subunit, respectively, we generated H139A/R140A double mutant and found it was inactive and became monomeric. Therefore, the multiple mutations apparently influence the integrity of the catalytic site due to the missing H-bonding network. Moreover, Met111, also on the highly conserved helix F, was necessary for dimer formation and enzyme activity. When Met111 was replaced with Glu, the negative-charged repulsion converted half of the dimer into a monomer. In conclusion, the H-bonds mainly through N101 for maintaining substrate binding stability and the hydrophobic interaction of M111 in dimer interface are essential for activity of yeast GGPPS.

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

PubMed

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.

Effects of yeast and bran on phytate degradation and minerals in rice bread.

PubMed

Kadan, R S; Phillippy, B Q

2007-05-01

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

Potential spoilage yeasts in winery environments: Characterization and proteomic analysis of Trigonopsis cantarellii.

PubMed

Portugal, Cauré; Pinto, Luís; Ribeiro, Miguel; Tenorio, Carmen; Igrejas, Gilberto; Ruiz-Larrea, Fernanda

2015-10-01

Wine microbiota is complex and includes a wide diversity of yeast species. Few of them are able to survive under the restrictive conditions of dry red wines. In our study we detected and identified seven yeast species of the order Saccharomycetales that can be considered potential spoilers of wines due to physiological traits such as acidogenic metabolism and off-odor generation: Arthroascus schoenii, Candida ishiwadae, Meyerozyma guilliermondii, Pichia holstii, Pichia manshurica, Trigonopsis cantarellii, and Trigonopsis variabilis. Based on the prevalence of T. cantarellii isolates in the wine samples of our study, we further characterized this species, determined molecular and phenotypic features, and performed a proteomic analysis to identify differentially expressed proteins at mid-exponential growth phase in the presence of ethanol in the culture broth. This yeast species is shown to be able to grow in the presence of ethanol by expressing heat shock proteins (Hsp70, Hsp71) and a DNA damage-related protein (Rad24), and to be able to confer spoilage characteristics on wine. Copyright © 2015 Elsevier B.V. All rights reserved.

21 CFR 172.842 - Sorbitan monostearate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... alone as a rehydration aid in the production of active dry yeast in an amount not to exceed 1 percent by weight of the dry yeast. (7) As an emulsifier, alone or in combination with polysorbate 60, in the...

Identification of oleaginous yeast strains able to accumulate high intracellular lipids when cultivated in alkaline pretreated corn stover

PubMed Central

Sitepu, Irnayuli R.; Jin, Mingjie; Fernandez, J. Enrique; da Costa Sousa, Leonardo; Balan, Venkatesh; Boundy-Mills, Kyria L.

2015-01-01

Microbial oil is a potential alternative to food/plant-derived biodiesel fuel. Our previous screening studies identified a wide range of oleaginous yeast species, using a defined laboratory medium known to stimulate lipid accumulation. In this study, the ability of these yeasts to grow and accumulate lipids was further investigated in synthetic hydrolysate (SynH) and authentic ammonia fiber expansion (AFEX™)-pretreated corn stover hydrolysate (ACSH). Most yeast strains tested were able to accumulate lipids in SynH, but only a few were able to grow and accumulate lipids in ACSH medium. Cryptococcus humicola UCDFST 10-1004 was able to accumulate as high as 15.5 g/L lipids, out of a total of 36 g/L cellular biomass when grown in ACSH, with a cellular lipid content of 40% of cell dry weight. This lipid production is among the highest reported values for oleaginous yeasts grown in authentic hydrolysate. Pre-culturing in SynH media with xylose as sole carbon source enabled yeasts to assimilate both glucose and xylose more efficiently in the subsequent hydrolysate medium. This study demonstrates that ACSH is a suitable medium for certain oleaginous yeasts to convert lignocellullosic sugars to triacylglycerols for production of biodiesel and other valuable oleochemicals. PMID:25052467

Antimicrobial activity of broccoli (Brassica oleracea var. italica) cultivar Avenger against pathogenic bacteria, phytopathogenic filamentous fungi and yeast.

PubMed

Pacheco-Cano, R D; Salcedo-Hernández, R; López-Meza, J E; Bideshi, D K; Barboza-Corona, J E

2018-01-01

The objective of this study was to show whether the edible part of broccoli has antibacterial and antifungal activity against micro-organism of importance in human health and vegetable spoilage, and to test if this effect was partially due to antimicrobial peptides (AMPs). Crude extracts were obtained from florets and stems of broccoli cultivar Avenger and the inhibitory effect was demonstrated against pathogenic bacteria (Bacillus cereus, Staphylococcus xylosus, Staphylococcus aureus, Shigella flexneri, Shigella sonnei, Proteus vulgaris), phytopathogenic fungi (Colletotrichum gloeosporioides, Asperigillus niger) and yeasts (Candida albicans and Rhodotorula sp.). It was shown that samples treated with proteolytic enzymes had a reduction of approximately 60% in antibacterial activity against Staph. xylosus, suggesting that proteinaceous compounds might play a role in the inhibitory effect. Antimicrobial components in crude extracts were thermoresistant and the highest activity was observed under acidic conditions. It was shown that antifungal activity of broccoli's crude extracts might not be attributed to chitinases. Organic broccoli cultivar Avenger has antimicrobial activity against pathogenic bacteria, yeast and phytophatogenic fungi. Data suggest that this effect is partially due to AMPs. Broccoli's crude extracts have activity not only against pathogenic bacteria but also against phytophatogenic fungi of importance in agriculture. We suggest for first time that the inhibitory effect is probably due to AMPs. © 2017 The Society for Applied Microbiology.

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

PubMed

Hubenova, Yolina; Georgiev, Danail; Mitov, Mario

2014-09-01

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

T-screen and yeast assay for the detection of the thyroid-disrupting activities of cadmium, mercury, and zinc.

PubMed

Li, Jian; Liu, Yun; Kong, Dongdong; Ren, Shujuan; Li, Na

2016-05-01

In the present study, a two-hybrid yeast bioassay and a T-screen were used to screen for the thyroid receptor (TR)-disrupting activity of select metallic compounds (CdCl2, ZnCl2, HgCl2, CuSO4, MnSO4, and MgSO4). The results reveal that none of the tested metallic compounds showed TR-agonistic activity, whereas ZnCl2, HgCl2, and CdCl2 demonstrated TR antagonism. For the yeast assay, the dose-response relationship of these metallic compounds was established, and the concentrations producing 20 % of the maximum effect of ZnCl2, HgCl2, and CdCl2 were 9.1 × 10(-5), 3.2 × 10(-6), and 1.2 × 10(-6) mol/L, respectively. The T-screen also supported the finding that ZnCl2, HgCl2, and CdCl2 decreased the cell proliferation at concentrations ranging from 10(-6) to 10(-4) mol/L. Furthermore, the thyroid-disrupting activity of metallic compounds in environmental water samples collected from the Guanting Reservoir, Beijing, China was evaluated. Solid-phase extraction was used to separate the organic extracts, and a modified two-hybrid yeast bioassay revealed that the metallic compounds in the water samples could affect thyroid hormone-induced signaling by decreasing the binding of the thyroid hormone. The addition of ethylenediaminetetraacetic acid (30 mg/L) could eliminate the effects. Thus, the cause(s) of the thyroid toxicity in the water samples appeared to be partly related to the metallic compounds.

Engineering yeasts for raw starch conversion.

PubMed

van Zyl, W H; Bloom, M; Viktor, M J

2012-09-01

Next to cellulose, starch is the most abundant hexose polymer in plants, an import food and feed source and a preferred substrate for the production of many industrial products. Efficient starch hydrolysis requires the activities of both α-1,4 and α-1,6-debranching hydrolases, such as endo-amylases, exo-amylases, debranching enzymes, and transferases. Although amylases are widely distributed in nature, only about 10 % of amylolytic enzymes are able to hydrolyse raw or unmodified starch, with a combination of α-amylases and glucoamylases as minimum requirement for the complete hydrolysis of raw starch. The cost-effective conversion of raw starch for the production of biofuels and other important by-products requires the expression of starch-hydrolysing enzymes in a fermenting yeast strain to achieve liquefaction, hydrolysis, and fermentation (Consolidated Bioprocessing, CBP) by a single organism. The status of engineering amylolytic activities into Saccharomyces cerevisiae as fermentative host is highlighted and progress as well as challenges towards a true CBP organism for raw starch is discussed. Conversion of raw starch by yeast secreting or displaying α-amylases and glucoamylases on their surface has been demonstrated, although not at high starch loading or conversion rates that will be economically viable on industrial scale. Once efficient conversion of raw starch can be demonstrated at commercial level, engineering of yeast to utilize alternative substrates and produce alternative chemicals as part of a sustainable biorefinery can be pursued to ensure the rightful place of starch converting yeasts in the envisaged bio-economy of the future.

Genetic and phenotypic characteristics of baker's yeast: relevance to baking.

PubMed

Randez-Gil, Francisca; Córcoles-Sáez, Isaac; Prieto, José A

2013-01-01

Yeasts rarely encounter ideal physiological conditions during their industrial life span; therefore, their ability to adapt to changing conditions determines their usefulness and applicability. This is especially true for baking strains of Saccharomyces cerevisiae. The success of this yeast in the ancient art of bread making is based on its capacity to rapidly transform carbohydrates into CO2 rather than its unusual resistance to environmental stresses. Moreover, baker's yeast must exhibit efficient respiratory metabolism during yeast manufacturing, which determines biomass yield. However, optimal growth conditions often have negative consequences in other commercially important aspects, such as fermentative power or stress tolerance. This article reviews the genetic and physiological characteristics of baking yeast strains, emphasizing the activation of regulatory mechanisms in response to carbon source and stress signaling and their importance in defining targets for strain selection and improvement.

Tombusvirus RNA replication depends on the TOR pathway in yeast and plants.

PubMed

Inaba, Jun-Ichi; Nagy, Peter D

2018-06-01

Similar to other (+)RNA viruses, tomato bushy stunt virus (TBSV) utilizes metabolites, lipids, membranes, and co-opted host factors during replication. The coordination of cell metabolism and growth with environmental cues is performed by the target of rapamycin (TOR) kinase in eukaryotic cells. In this paper, we find that TBSV replication partially inhibits TOR activity, likely due to recruitment of glycolytic enzymes to the viral replication compartment, which results in reduced ATP levels in the cytosol. Complete inhibition of TOR activity with rapamycin in yeast or AZD8055 inhibitor in plants reduces tombusvirus replication. We find that high glucose concentration, which stimulates TOR activity, enhanced tombusvirus replication in yeast. Depletion of yeast Sch9 or plant S6K1 kinase, a downstream effector of TOR, also inhibited tombusvirus replication in yeast and plant or the assembly of the viral replicase in vitro. Altogether, the TOR pathway is crucial for TBSV to replicate efficiently in hosts. Copyright © 2018 Elsevier Inc. All rights reserved.

Crystal structures of the adenylate sensor from fission yeast AMP-activated protein kinase.

PubMed

Townley, Robert; Shapiro, Lawrence

2007-03-23

The 5'-AMP (adenosine monophosphate)-activated protein kinase (AMPK) coordinates metabolic function with energy availability by responding to changes in intracellular ATP (adenosine triphosphate) and AMP concentrations. Here, we report crystal structures at 2.9 and 2.6 A resolution for ATP- and AMP-bound forms of a core alphabetagamma adenylate-binding domain from the fission yeast AMPK homolog. ATP and AMP bind competitively to a single site in the gamma subunit, with their respective phosphate groups positioned near function-impairing mutants. Unexpectedly, ATP binds without counterions, amplifying its electrostatic effects on a critical regulatory region where all three subunits converge.

Recovery of Fuel-Precursor Lipids from Oleaginous Yeast

DOE PAGES

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

2018-01-24

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

Recovery of Fuel-Precursor Lipids from Oleaginous Yeast

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

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

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

Use of the yeast-like cells of Tremella fuciformis as a cell factory to produce a Pleurotus ostreatus hydrophobin.

PubMed

Zhu, Hanyu; Liu, Dongmei; Wang, Yuanyuan; Ren, Danfeng; Zheng, Liesheng; Chen, Liguo; Ma, Aimin

2017-08-01

To obtain hydrophobin, a Class I hydrophobin gene, Po.hyd from Pleurotus ostreatus, was transformed into the yeast-like cells of Tremella fuciformis using Agrobacterium tumefaciens. The hydrophobin Po.HYD from P. ostreatus was heterogeneously expressed by the yeast-like cells of T. fuciformis. Plasmids harboring the Po.hyd gene driven by endogenous glyceraldehyde-3-phosphate dehydrogenase promoter were transformed by A. tumefaciens. The integration and expression of the rPo.HYD in the T. fuciformis cells were confirmed by PCR, Southern blot, fluorescence microscopy and quantitative real-time PCR. SDS-PAGE demonstrated that the rPo.HYD was extracted with the expected MW of 14 kDa. The yield of purified rPo.HYD was 0.58 mg/g dry wt. The protein, with its ability to stabilize oil droplets, exhibited a better emulsifying activity than the typical food emulsifiers Tween 20 and sodium caseinate. Tremella fuciformis can be used as a cell factory to produce hydrophobin on a large scale for the food industry.

Solution structures, dynamics, and ice growth inhibitory activity of peptide fragments derived from an antarctic yeast protein.

PubMed

Shah, Syed Hussinien H; Kar, Rajiv K; Asmawi, Azren A; Rahman, Mohd Basyaruddin A; Murad, Abdul Munir A; Mahadi, Nor M; Basri, Mahiran; Rahman, Raja Noor Zaliha A; Salleh, Abu B; Chatterjee, Subhrangsu; Tejo, Bimo A; Bhunia, Anirban

2012-01-01

Exotic functions of antifreeze proteins (AFP) and antifreeze glycopeptides (AFGP) have recently been attracted with much interest to develop them as commercial products. AFPs and AFGPs inhibit ice crystal growth by lowering the water freezing point without changing the water melting point. Our group isolated the Antarctic yeast Glaciozyma antarctica that expresses antifreeze protein to assist it in its survival mechanism at sub-zero temperatures. The protein is unique and novel, indicated by its low sequence homology compared to those of other AFPs. We explore the structure-function relationship of G. antarctica AFP using various approaches ranging from protein structure prediction, peptide design and antifreeze activity assays, nuclear magnetic resonance (NMR) studies and molecular dynamics simulation. The predicted secondary structure of G. antarctica AFP shows several α-helices, assumed to be responsible for its antifreeze activity. We designed several peptide fragments derived from the amino acid sequences of α-helical regions of the parent AFP and they also showed substantial antifreeze activities, below that of the original AFP. The relationship between peptide structure and activity was explored by NMR spectroscopy and molecular dynamics simulation. NMR results show that the antifreeze activity of the peptides correlates with their helicity and geometrical straightforwardness. Furthermore, molecular dynamics simulation also suggests that the activity of the designed peptides can be explained in terms of the structural rigidity/flexibility, i.e., the most active peptide demonstrates higher structural stability, lower flexibility than that of the other peptides with lower activities, and of lower rigidity. This report represents the first detailed report of downsizing a yeast AFP into its peptide fragments with measurable antifreeze activities.

Solution Structures, Dynamics, and Ice Growth Inhibitory Activity of Peptide Fragments Derived from an Antarctic Yeast Protein

PubMed Central

Asmawi, Azren A.; Rahman, Mohd Basyaruddin A.; Murad, Abdul Munir A.; Mahadi, Nor M.; Basri, Mahiran; Rahman, Raja Noor Zaliha A.; Salleh, Abu B.; Chatterjee, Subhrangsu; Tejo, Bimo A.; Bhunia, Anirban

2012-01-01

Exotic functions of antifreeze proteins (AFP) and antifreeze glycopeptides (AFGP) have recently been attracted with much interest to develop them as commercial products. AFPs and AFGPs inhibit ice crystal growth by lowering the water freezing point without changing the water melting point. Our group isolated the Antarctic yeast Glaciozyma antarctica that expresses antifreeze protein to assist it in its survival mechanism at sub-zero temperatures. The protein is unique and novel, indicated by its low sequence homology compared to those of other AFPs. We explore the structure-function relationship of G. antarctica AFP using various approaches ranging from protein structure prediction, peptide design and antifreeze activity assays, nuclear magnetic resonance (NMR) studies and molecular dynamics simulation. The predicted secondary structure of G. antarctica AFP shows several α-helices, assumed to be responsible for its antifreeze activity. We designed several peptide fragments derived from the amino acid sequences of α-helical regions of the parent AFP and they also showed substantial antifreeze activities, below that of the original AFP. The relationship between peptide structure and activity was explored by NMR spectroscopy and molecular dynamics simulation. NMR results show that the antifreeze activity of the peptides correlates with their helicity and geometrical straightforwardness. Furthermore, molecular dynamics simulation also suggests that the activity of the designed peptides can be explained in terms of the structural rigidity/flexibility, i.e., the most active peptide demonstrates higher structural stability, lower flexibility than that of the other peptides with lower activities, and of lower rigidity. This report represents the first detailed report of downsizing a yeast AFP into its peptide fragments with measurable antifreeze activities. PMID:23209600

L-arabinose fermenting yeast

DOEpatents

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

2010-12-07

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

Potentiality of yeast Candida sp. SMN04 for degradation of cefdinir, a cephalosporin antibiotic: kinetics, enzyme analysis and biodegradation pathway.

PubMed

Selvi, A; Das, Devlina; Das, Nilanjana

2015-01-01

A new yeast strain isolated from the pharmaceutical wastewater was capable of utilizing cefdinir as a sole carbon source for their growth in mineral medium. The yeast was identified and named as Candida sp. SMN04 based on morphology and 18S-ITS-D1/D2/D3 rRNA sequence analysis. The interaction between factors pH (3.0-9.0), inoculum dosage (1-7%), time (1-11 day) and cefdinir concentration (50-450 mg/L) was studied using a Box-Behnken design. The factors were studied as a result of their effect on cell dry weight (R1; g/L), extended spectrum β-lactamase (ESBL) assay (R2; mm), P450 activity (R3; U/mL) and degradation (R4; %). Maximum values of R1, R2, R3 and R4 were obtained at central values of all the parameters. The isolated yeast strain efficiently degraded 84% of 250 mg L⁻¹ of cefdinir within 6 days with a half-life of 2.97 days and degradation rate constant of 0.2335 per day. Pseudo-first-order model efficiently described the process. Among the various enzymes tested, the order of activity at the end of Day 4 was noted to be: cytochrome P450 (1.76 ± 0.03) > NADPH reductase (1.51 ± 0.20) > manganese peroxidase and amylase (0.66 ± 0.15; 0.66 ± 0.70). Intermediates were successfully characterized by liquid chromatography-mass spectrometry. The opening of the β-lactam ring involving ESBL activity was considered as one of the major steps in the cefdinir degradation process. Fourier transform-infrared spectroscopy analysis showed the absence of spectral vibrations between 1766 and 1519 cm⁻¹ confirming the complete removal of lactam ring during cefdinir degradation. The results of the present study are promising for the use of isolated yeast Candida sp. SMN04 as a potential bioremediation agent.

Enzymes in Glycolysis and the Citric Acid Cycle in the Yeast and Mycelial Forms of Paracoccidioides brasiliensis

PubMed Central

Kanetsuna, Fuminori; Carbonell, Luis M.

1966-01-01

Kanetsuna, Fuminori (Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela), and Luis M. Carbonell. Enzymes in glycolysis and the citric acid cycle in the yeast and mycelial forms of Paracoccidioides brasiliensis. J. Bacteriol. 92:1315–1320. 1966.—Enzymatic activities in glycolysis, the hexose monophosphate shunt, and the citric acid cycle in cell-free extracts of the yeast and mycelial forms of Paracoccidioides brasiliensis were examined comparatively. Both forms have the enzymes of these pathways. Activities of glucose-6-phosphate dehydrogenase and malic dehydrogenase of the mycelial form were higher than those of the yeast form. Another 15 enzymatic activities of the mycelial form were lower than those of the yeast form. The activity of glyceraldehyde-3-phosphate dehydrogenase showed the most marked difference between the two forms, its activity in the mycelial form being about 20% of that in the yeast form. PMID:5924267

Genome dynamics and evolution in yeasts: A long-term yeast-bacteria competition experiment

PubMed Central

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

2018-01-01

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

SNPs Altering Ammonium Transport Activity of Human Rhesus Factors Characterized by a Yeast-Based Functional Assay

PubMed Central

Deschuyteneer, Aude; Boeckstaens, Mélanie; De Mees, Christelle; Van Vooren, Pascale; Wintjens, René; Marini, Anna Maria

2013-01-01

Proteins of the conserved Mep-Amt-Rh family, including mammalian Rhesus factors, mediate transmembrane ammonium transport. Ammonium is an important nitrogen source for the biosynthesis of amino acids but is also a metabolic waste product. Its disposal in urine plays a critical role in the regulation of the acid/base homeostasis, especially with an acid diet, a trait of Western countries. Ammonium accumulation above a certain concentration is however pathologic, the cytotoxicity causing fatal cerebral paralysis in acute cases. Alteration in ammonium transport via human Rh proteins could have clinical outcomes. We used a yeast-based expression assay to characterize human Rh variants resulting from non synonymous single nucleotide polymorphisms (nsSNPs) with known or unknown clinical phenotypes and assessed their ammonium transport efficiency, protein level, localization and potential trans-dominant impact. The HsRhAG variants (I61R, F65S) associated to overhydrated hereditary stomatocytosis (OHSt), a disease affecting erythrocytes, proved affected in intrinsic bidirectional ammonium transport. Moreover, this study reveals that the R202C variant of HsRhCG, the orthologue of mouse MmRhcg required for optimal urinary ammonium excretion and blood pH control, shows an impaired inherent ammonium transport activity. Urinary ammonium excretion was RHcg gene-dose dependent in mouse, highlighting MmRhcg as a limiting factor. HsRhCGR202C may confer susceptibility to disorders leading to metabolic acidosis for instance. Finally, the analogous R211C mutation in the yeast ScMep2 homologue also impaired intrinsic activity consistent with a conserved functional role of the preserved arginine residue. The yeast expression assay used here constitutes an inexpensive, fast and easy tool to screen nsSNPs reported by high throughput sequencing or individual cases for functional alterations in Rh factors revealing potential causal variants. PMID:23967154

Antimicrobial activity of some Pacific Northwest woods against anaerobic bacteria and yeast.

PubMed

Johnston, W H; Karchesy, J J; Constantine, G H; Craig, A M

2001-11-01

Extracts of woods commonly used for animal bedding were tested for antimicrobial activity. Essential oils from Alaska cedar (Chamaecyparis nootkatensis), western juniper (Juniperus occidentalis) and old growth Douglas fir (Pseudotsuga menziesii) as well as methanol extracts of wood from these trees plus western red cedar (Thuja plicata) and ponderosa pine (Pinus ponderosa) were tested for antimicrobial activity against anaerobic bacteria and yeast. The test microbes included Fusobacterium necrophorum, Clostridium perfringens, Actinomyces bovis and Candida albicans which are common to foot diseases and other infections in animals. The essential oils and methanol extracts were tested using a standardized broth assay. Only extracts of Alaska cedar and western juniper showed significant antimicrobial activity against each of the microbes tested. The essential oil of Douglas fir did show antimicrobial activity against A. bovis at the concentrations tested. The methanol extracts of the heartwood of Douglas fir and the sapwood of ponderosa pine showed no antimicrobial activity. The major chemical components of western juniper (cedrol and alpha- and beta-cedrene) and Alaska cedar (nootkatin) were also tested. In western juniper, alpha- and beta-cedrene were found to be active components. Nootkatin showed activity only against C. albicans. The inhibitory activity in Alaska cedar oil was high enough to justify further efforts to define the other chemical components responsible for the antimicrobial activity. Copyright 2001 John Wiley & Sons, Ltd.

Allicin disrupts the cell's electrochemical potential and induces apoptosis in yeast.

PubMed

Gruhlke, Martin C H; Portz, Daniela; Stitz, Michael; Anwar, Awais; Schneider, Thomas; Jacob, Claus; Schlaich, Nikolaus L; Slusarenko, Alan J

2010-12-15

The volatile substance allicin gives crushed garlic (Allium sativum) its characteristic odor and is a pro-oxidant that undergoes thiol-disulfide exchange reactions with -SH groups in proteins and glutathione. The antimicrobial activity of allicin is suspected to be due to the oxidative inactivation of essential thiol-containing enzymes. We investigated the hypothesis that at threshold inhibitory levels allicin can shunt yeast cells into apoptosis by altering their overall redox status. Yeast cells were treated either with chemically synthesized, pure allicin or with allicin in garlic juice. Allicin-dependent cell oxidation was demonstrated with a redox-sensitive GFP construct and the shift in cellular electrochemical potential (E(hc)) from less than -215 to -181mV was calculated using the Nernst equation after the glutathione/glutathione disulfide couple (2GSH/GSSG) in the cell was quantified. Caspase activation occurred after allicin treatment, and yeast expressing a human antiapoptotic Bcl-XL construct was rendered more resistant to allicin. Also, a yeast apoptosis-inducing factor deletion mutant was more resistant to allicin than wild-type cells. We conclude that allicin in garlic juice can activate apoptosis in yeast cells through its oxidizing properties and that this presents an alternative cell-killing mechanism to the previously proposed specific oxidative inactivation of essential enzymes. Copyright © 2010 Elsevier Inc. All rights reserved.

Effect of Freeze-Drying on the Antioxidant Compounds and Antioxidant Activity of Selected Tropical Fruits

PubMed Central

Shofian, Norshahida Mohamad; Hamid, Azizah Abdul; Osman, Azizah; Saari, Nazamid; Anwar, Farooq; Dek, Mohd Sabri Pak; Hairuddin, Muhammad Redzuan

2011-01-01

The effects of freeze-drying on antioxidant compounds and antioxidant activity of five tropical fruits, namely starfruit (Averrhoa carambola L.), mango (Mangifera indica L.), papaya (Carica papaya L.), muskmelon (Cucumis melo L.), and watermelon Citruluss lanatus (Thunb.) were investigated. Significant (p < 0.05) differences, for the amounts of total phenolic compounds (TPC), were found between the fresh and freeze-dried fruit samples, except muskmelon. There was no significant (p > 0.05) change, however, observed in the ascorbic acid content of the fresh and freeze-dried fruits. Similarly, freeze-drying did not exert any considerable effect on β-carotene concentration of fruits, except for mango and watermelon, where significantly (p < 0.05) higher levels were detected in the fresh samples. The results of DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging and reducing power assays revealed that fresh samples of starfruit and mango had relatively higher antioxidant activity. In case of linoleic acid peroxidation inhibition measurement, a significant (p < 0.05) but random variation was recorded between the fresh and freeze-dried fruits. Overall, in comparison to β-carotene and ascorbic acid, a good correlation was established between the result of TPC and antioxidant assays, indicating that phenolics might have been the dominant compounds contributing towards the antioxidant activity of the fruits tested. PMID:21845104

Effect of freeze-drying on the antioxidant compounds and antioxidant activity of selected tropical fruits.

PubMed

Shofian, Norshahida Mohamad; Hamid, Azizah Abdul; Osman, Azizah; Saari, Nazamid; Anwar, Farooq; Dek, Mohd Sabri Pak; Hairuddin, Muhammad Redzuan

2011-01-01

The effects of freeze-drying on antioxidant compounds and antioxidant activity of five tropical fruits, namely starfruit (Averrhoa carambola L.), mango (Mangifera indica L.), papaya (Carica papaya L.), muskmelon (Cucumis melo L.), and watermelon Citruluss lanatus (Thunb.) were investigated. Significant (p < 0.05) differences, for the amounts of total phenolic compounds (TPC), were found between the fresh and freeze-dried fruit samples, except muskmelon. There was no significant (p > 0.05) change, however, observed in the ascorbic acid content of the fresh and freeze-dried fruits. Similarly, freeze-drying did not exert any considerable effect on β-carotene concentration of fruits, except for mango and watermelon, where significantly (p < 0.05) higher levels were detected in the fresh samples. The results of DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging and reducing power assays revealed that fresh samples of starfruit and mango had relatively higher antioxidant activity. In case of linoleic acid peroxidation inhibition measurement, a significant (p < 0.05) but random variation was recorded between the fresh and freeze-dried fruits. Overall, in comparison to β-carotene and ascorbic acid, a good correlation was established between the result of TPC and antioxidant assays, indicating that phenolics might have been the dominant compounds contributing towards the antioxidant activity of the fruits tested.

Effect of different aging techniques on the polysaccharide and phenolic composition and sensory characteristics of Syrah red wines fermented using different yeast strains.

PubMed

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

2015-07-15

The effect of high levels of the polysaccharide Saccharomyces cerevisiae yeast strain (HPS) and another conventional yeast strain (FERM) on the polysaccharide and phenolic composition of Syrah red wines during alcoholic fermentation and subsequent aging on lees, with or without oak wood chips, and on inactive dry yeast was investigated. The HPS yeast released higher amounts of polysaccharides during alcoholic fermentation than FERM yeast (485 g L(-1) and 403 g L(-1), respectively) and after the aging period (516 g L(-1) and 500 g L(-1), respectively). The different aging techniques increased the polysaccharide concentration; the concentration was dependent on the aging technique applied. The interaction of the polysaccharides with the phenolic compounds depended on the yeast strain, aging technique, aging period and compound analysed. The HPS wines exhibited better sensory characteristics than the FERM wines after alcoholic fermentation; however, during the aging period, it was difficult to determine which technique produced the best wine due to the interactions of aging technique, aging period and sensory attribute evaluated. Copyright © 2015 Elsevier Ltd. All rights reserved.

High-grain diets supplemented with phytogenic compounds or autolyzed yeast modulate ruminal bacterial community and fermentation in dry cows.

PubMed

Neubauer, V; Petri, R; Humer, E; Kröger, I; Mann, E; Reisinger, N; Wagner, M; Zebeli, Q

2018-03-01

The feeding of concentrate-rich diets may lead to microbial imbalances and dysfermentation in the rumen. The main objective of this study was to determine the effects of supplementing phytogenic compounds (PHY) or autolyzed yeast (AY) on rumen fermentation and microbial abundance in cows intermittently fed concentrate-rich diets. The experiment was carried out as an incomplete 3 × 4 Latin square design, with 8 nonlactating rumen-fistulated Holstein-Friesian cows. The cows were randomly assigned to a concentrate diet that was either not supplemented (CON), or supplemented with PHY or AY. Each of the 4 consecutive experimental periods was composed of a 1-wk roughage-only diet (RD), 6-d gradual concentrate increase, followed by 1 wk of 65% concentrate (dry matter basis; Conc I), and 1 wk of RD and a final 2-wk 65% concentrate (dry matter basis; Conc II) phase. Digesta samples were collected from the rumen mat for bacterial 16S rRNA gene Illumina MiSeq (Illumina, Balgach, Switzerland) sequencing, and samples of particle-associated rumen liquid were obtained for measuring short-chain fatty acids, lactate, ammonia, and pH during RD (d 6), Conc I (d 19), and Conc II (d 39). The concentrate feeding caused a decrease of overall bacterial diversity indices, especially during Conc I. The genera Ruminococcus, Butyrivibrio, and Coprococcus were decreased, whereas Prevotella, Megasphaera, Lachnospira, and Bacteroides were increased in abundance. Supplementation of both feed additives increased the abundance of gram-positive and decreased that of gram-negative bacteria. Supplementation of AY enhanced cellulolytic bacteria such as Ruminococcus spp., whereas PHY decreased starch and sugar fermenters including Bacteroides spp., Shuttleworthia spp., and Syntrophococcus spp. Moreover, PHY supplementation increased butyrate percentage in the rumen in both concentrate phases. In conclusion, intermittent high-concentrate feeding altered the digesta-associated rumen bacterial community

Chemical characterization and antioxidant activities comparison in fresh, dried, stir-frying and carbonized ginger.

PubMed

Li, Yuxin; Hong, Yan; Han, Yanquan; Wang, Yongzhong; Xia, Lunzhu

2016-02-01

Ginger (Zingiber officinale Rosc.) is a common dietary adjunct that contributes to the taste and flavor of foods, and is also an important Traditional Chinese medicine (TCM). Different processing methods can produce different processed gingers with dissimilar chemical constituents and pharmacological activities. In this study, an ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/QTOF-MS) was applied to identify the complicated components from fresh, dried, stir-frying and carbonized ginger extracts. All of the 27 compounds were identified from four kinds of ginger samples (fresh, dried, stir-frying and carbonized ginger). Five main constituents (zingerone, 6-gingerol, 8-gingerol, 6-shogaol and 10-gingerol) in these four kinds of ginger sample extracts were simultaneously determined by UPLC-PDA. Meanwhile, the antioxidant effect of fresh, dried, stir-frying and carbonized gingers were evaluated by three assays (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis(3-ethylbenzthiazolinesulfonic acid) diammonium salt (ABTS), and ferric reducing antioxidant power (FRAP)). The results demonstrated that antioxidant activity of dried ginger was the highest, for its phenolic contents are 5.2-, 1.1- and 2.4-fold higher than that of fresh, stir-frying and carbonized ginger, respectively, the antioxidant activities' results indicated a similar tendency with phenolic contents: dried ginger>stir-frying ginger>fresh ginger>carbonized ginger. The processing contributed to the decreased concentration of gingerols and the increased levels of shogaols, which reducing the antioxidant effects in pace with processing. This study elucidated the relationship of the heating process with the constituents and antioxidant activity, and provided a guide for choosing different kinds of ginger samples on clinical application. Copyright © 2016 Elsevier B.V. All rights reserved.

Improved shelf life of dried Beauveria bassiana blastospores using convective drying and active packaging processes

USDA-ARS?s Scientific Manuscript database

The yeast form (blastospore) of the dimorphic insect-pathogenic fungus Beauveria bassiana can be rapidly produced using liquid fermentation methods but is generally unable to survive rapid dehydration processes or storage under non-refrigerated conditions. In this study, we evaluated the influence o...

Active Yeast Telomerase Shares Subunits with Ribonucleoproteins RNase P and RNase MRP.

PubMed

Lemieux, Bruno; Laterreur, Nancy; Perederina, Anna; Noël, Jean-François; Dubois, Marie-Line; Krasilnikov, Andrey S; Wellinger, Raymund J

2016-05-19

Telomerase is the ribonucleoprotein enzyme that replenishes telomeric DNA and maintains genome integrity. Minimally, telomerase activity requires a templating RNA and a catalytic protein. Additional proteins are required for activity on telomeres in vivo. Here, we report that the Pop1, Pop6, and Pop7 proteins, known components of RNase P and RNase MRP, bind to yeast telomerase RNA and are essential constituents of the telomerase holoenzyme. Pop1/Pop6/Pop7 binding is specific and involves an RNA domain highly similar to a protein-binding domain in the RNAs of RNase P/MRP. The results also show that Pop1/Pop6/Pop7 function to maintain the essential components Est1 and Est2 on the RNA in vivo. Consistently, addition of Pop1 allows for telomerase activity reconstitution with wild-type telomerase RNA in vitro. Thus, the same chaperoning module has allowed the evolution of functionally and, remarkably, structurally distinct RNPs, telomerase, and RNases P/MRP from unrelated progenitor RNAs. Copyright © 2016 Elsevier Inc. All rights reserved.

HIV-1 Protease in the Fission Yeast Schizosaccharomyces pombe.

PubMed

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

2016-01-01

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

[The in vitro antifungal activities of fluconazole against pathogenic yeasts recently isolated from clinical specimens].

PubMed

Yamaguchi, H; Igari, J; Kume, H; Abe, M; Oguri, T; Kanno, H; Kawakami, S; Okuzumi, K; Fukayama, M; Ito, A; Kawata, K; Uchida, K

1997-09-01

The emergence of Candida albicans resistance to azole antifungal agents have been reported in the U. S. and Europe. We examined the in vitro antifungal activities of fluconazole against clinical isolates collected by seven investigators in three years to examine if a tendency existed toward the development of azole-resistance among fungal isolates in Japan. The following results were obtained: 1. Sensitivities to fluconazole (FLCZ) were determined for yeast-like fungi, including 113 strains isolated in 1993, 149 strains isolated in 1994 and 205 strains isolated in 1995. No significant differences in sensitivities in the three years were detected. 2. Minimum inhibitory concentrations of FLCZ were 0.1-0.78 microgram/ml for C. albicans and 3.13-25 micrograms/ml for C. glabrata. Strains with 25 micrograms/ml of FLCZ's MIC were detected; two strains of C. krusei and one strain each of C. krusei, Trichospron beigelii and Hansenula anomala. No strains with higher than 50 micrograms/ml MIC of FLCZ were detected. 3. In vitro activities of FLCZ were compared between clinical strains isolated between 1993 and 1995 and clinical strains isolated before the marketing of FLCZ (up to December 1987) or clinical yeasts isolated between 1991 and 1992. No significant differences were observed, suggesting that no tendency existed toward azole resistance among fungal strains examined.

Antarctic Yeasts: Biodiversity and Potential Applications

NASA Astrophysics Data System (ADS)

Shivaji, S.; Prasad, G. S.

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

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

NASA Astrophysics Data System (ADS)

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

1984-06-01

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

Genetic and phenotypic diversity of autochthonous cider yeasts in a cellar from Asturias.

PubMed

Pando Bedriñana, R; Querol Simón, A; Suárez Valles, B

2010-06-01

This paper analyses yeast diversity and dynamics during the production of Asturian cider. Yeasts were isolated from apple juice and at different stages of fermentation in a cellar in Villaviciosa during two Asturian cider-apple harvests. The species identified by ITS-RFLP corresponded to Hanseniaspora valbyensis, Hanseniaspora uvarum, Metschnikowia pulcherrima, Pichia guilliermondii, Candida parapsilosis, Saccharomyces cerevisiae and Saccharomyces bayanus/Saccharomyces pastorianus/Saccharomyces kudriavzevii/Saccharomyces mikatae. The species C. parapsilosis is reported here for the first time in cider. The analysis of Saccharomyces mtDNA patterns showed great diversity, sequential substitution and the presence of a small number of yeast patterns (up to 8), present in both harvests. Killer (patterns nos. 22' and 47), sensitive (patterns nos. 12, 15, 33 and 61) and neutral phenotypes were found among the S. cerevisiae isolates. The detection of beta-glucosidase activity, with arbutin as the sole carbon source, allowed two S. cerevisiae strains (patterns nos. 3' and 19') to be differentiated by means of this enzymatic activity. Yeast strains producing the killer toxin or with beta-glucosidase activity are reported for the first time in autochthonous cider yeasts. 2009 Elsevier Ltd. All rights reserved.

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

PubMed

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

2017-06-01

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

Peptide (Lys-Leu) and amino acids (Lys and Leu) supplementations improve physiological activity and fermentation performance of brewer's yeast during very high-gravity (VHG) wort fermentation.

PubMed

Yang, Huirong; Zong, Xuyan; Cui, Chun; Mu, Lixia; Zhao, Haifeng

2017-12-22

Lys and Leu were generally considered as the key amino acids for brewer's yeast during beer brewing. In the present study, peptide Lys-Leu and a free amino acid (FAA) mixture of Lys and Leu (Lys + Leu) were supplemented in 24 °P wort to examine their effects on physiological activity and fermentation performance of brewer's yeast during very high-gravity (VHG) wort fermentation. Results showed that although both peptide Lys-Leu and their FAA mixture supplementations could increase the growth and viability, intracellular trehalose and glycerol content, wort fermentability, and ethanol content for brewer's yeast during VHG wort fermentation, and peptide was better than their FAA mixture at promoting growth and fermentation for brewer's yeast when the same dose was kept. Moreover, peptide Lys-Leu supplementation significantly increased the assimilation of Asp, but decreased the assimilation of Gly, Ala, Val, (Cys)2, Ile, Leu, Tyr, Phe, Lys, Arg, and Pro. However, the FAA mixture supplementation only promoted the assimilation of Lys and Leu, while reduced the absorption of total amino acids to a greater extent. Thus, the peptide Lys-Leu was more effective than their FAA mixture on the improvement of physiological activity, fermentation performance, and nitrogen metabolism of brewer's yeast during VHG wort fermentation. © 2017 International Union of Biochemistry and Molecular Biology, Inc.

Aerobic Stability and Effects of Yeasts during Deterioration of Non-fermented and Fermented Total Mixed Ration with Different Moisture Levels.

PubMed

Hao, W; Wang, H L; Ning, T T; Yang, F Y; Xu, C C

2015-06-01

The present experiment evaluated the influence of moisture level and anaerobic fermentation on aerobic stability of total mixed ration (TMR). The dynamic changes in chemical composition and microbial population that occur after air exposure were examined, and the species of yeast associated with the deterioration process were also identified in both non-fermented and fermented TMR to deepen the understanding of aerobic deterioration. The moisture levels of TMR in this experiment were adjusted to 400 g/kg (low moisture level, LML), 450 g/kg (medium moisture level, MML), and 500 g/kg (high moisture level, HML), and both non-fermented and 56-d-fermented TMR were subjected to air exposure to determine aerobic stability. Aerobic deterioration resulted in high losses of nutritional components and largely reduced dry matter digestibility. Non-fermented TMR deteriorated during 48 h of air exposure and the HML treatment was more aerobically unstable. On dry matter (DM) basis, yeast populations significantly increased from 10(7) to 10(10) cfu/g during air exposure, and Candida ethanolica was the predominant species during deterioration in non-fermented TMR. Fermented TMR exhibited considerable resistance to aerobic deterioration. Spoilage was only observed in the HML treatment and its yeast population increased dramatically to 10(9) cfu/g DM when air exposure progressed to 30 d. Zygosaccharomyces bailii was the sole yeast species isolated when spoilage occurred. These results confirmed that non-fermented and fermented TMR with a HML are more prone to spoilage, and fermented TMR has considerable resistance to aerobic deterioration. Yeasts can trigger aerobic deterioration in both non-fermented and fermented TMR. C. ethanolica may be involved in the spoilage of non-fermented TMR and the vigorous growth of Z. bailii can initiate aerobic deterioration in fermented TMR.

Aerobic Stability and Effects of Yeasts during Deterioration of Non-fermented and Fermented Total Mixed Ration with Different Moisture Levels

PubMed Central

Hao, W.; Wang, H. L.; Ning, T. T.; Yang, F. Y.; Xu, C. C.

2015-01-01

The present experiment evaluated the influence of moisture level and anaerobic fermentation on aerobic stability of total mixed ration (TMR). The dynamic changes in chemical composition and microbial population that occur after air exposure were examined, and the species of yeast associated with the deterioration process were also identified in both non-fermented and fermented TMR to deepen the understanding of aerobic deterioration. The moisture levels of TMR in this experiment were adjusted to 400 g/kg (low moisture level, LML), 450 g/kg (medium moisture level, MML), and 500 g/kg (high moisture level, HML), and both non-fermented and 56-d-fermented TMR were subjected to air exposure to determine aerobic stability. Aerobic deterioration resulted in high losses of nutritional components and largely reduced dry matter digestibility. Non-fermented TMR deteriorated during 48 h of air exposure and the HML treatment was more aerobically unstable. On dry matter (DM) basis, yeast populations significantly increased from 107 to 1010 cfu/g during air exposure, and Candida ethanolica was the predominant species during deterioration in non-fermented TMR. Fermented TMR exhibited considerable resistance to aerobic deterioration. Spoilage was only observed in the HML treatment and its yeast population increased dramatically to 109 cfu/g DM when air exposure progressed to 30 d. Zygosaccharomyces bailii was the sole yeast species isolated when spoilage occurred. These results confirmed that non-fermented and fermented TMR with a HML are more prone to spoilage, and fermented TMR has considerable resistance to aerobic deterioration. Yeasts can trigger aerobic deterioration in both non-fermented and fermented TMR. C. ethanolica may be involved in the spoilage of non-fermented TMR and the vigorous growth of Z. bailii can initiate aerobic deterioration in fermented TMR. PMID:25925059

Effect of drying methods with the application of vacuum microwaves on the bioactive compounds, color, and antioxidant activity of strawberry fruits.

PubMed

Wojdyło, Aneta; Figiel, Adam; Oszmiański, Jan

2009-02-25

The objective of this study was to evaluate the application of vacuum-microwave drying (240, 360, and 480 W) in the production process of dehydrated strawberry and to compare and contrast the quality of these dehydrated strawberries in terms of their polyphenol compounds, concentration of some heat liable components, and color to that of freeze-dried, convective, and vacuum-dried strawberry. Thus, the effect of vacuum-microwave drying and other drying methods on the antioxidant activity of berries was evaluated. Whole fresh and dried fruits were assessed for phenolics (anthocyanins, flavanols, hydroxycinnamic acids, and flavonols), ascorbic acid, and antioxidant activity (all parameters were calculated on a dry matter basis). Analysis of data shows that ellagic acid and flavanol changes were affected by drying techniques and cultivar. Drying destroyed anthocyanins, flavanols, and ascorbic acid, and there was a significant decrease in antioxidant activity. The most striking result was that conventional and vacuum drying decreased antioxidant activity in both cultivars, whereas contradictory results were found for vacuum-microwave processed strawberry. This study has demonstrated that vacuum-microwave drying, especially at 240 W, can produce high-quality products, with the additional advantage of reduced processing times, compared to other processes such as freeze-drying.

Vegemite Beer: yeast extract spreads as nutrient supplements to promote fermentation.

PubMed

Kerr, Edward D; Schulz, Benjamin L

2016-01-01

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

Functional conservation of the yeast and Arabidopsis RAD54-like genes.

PubMed

Klutstein, Michael; Shaked, Hezi; Sherman, Amir; Avivi-Ragolsky, Naomi; Shema, Efrat; Zenvirth, Drora; Levy, Avraham A; Simchen, Giora

2008-04-01

The Saccharomyces cerevisiae RAD54 gene has critical roles in DNA double-strand break repair, homologous recombination, and gene targeting. Previous results show that the yeast gene enhances gene targeting when expressed in Arabidopsis thaliana. In this work we address the trans-species compatibility of Rad54 functions. We show that overexpression of yeast RAD54 in Arabidopsis enhances DNA damage resistance severalfold. Thus, the yeast gene is active in the Arabidopsis homologous-recombination repair system. Moreover, we have identified an A. thaliana ortholog of yeast RAD54, named AtRAD54. This gene, with close sequence similarity to RAD54, complements methylmethane sulfonate (MMS) sensitivity but not UV sensitivity or gene targeting defects of rad54Delta mutant yeast cells. Overexpression of AtRAD54 in Arabidopsis leads to enhanced resistance to DNA damage. This gene's assignment as a RAD54 ortholog is further supported by the interaction of AtRad54 with AtRad51 and the interactions between alien proteins (i.e., yeast Rad54 with AtRAD51 and yeast Rad51 with AtRad54) in a yeast two-hybrid experiment. These interactions hint at the molecular nature of this interkingdom complementation, although the stronger effect of the yeast Rad54 in plants than AtRad54 in yeast might be explained by an ability of the Rad54 protein to act alone, independently of its interaction with Rad51.

Vaginal yeast infection

MedlinePlus

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

The yeast Hot1 transcription factor is critical for activating a single target gene, STL1

PubMed Central

Bai, Chen; Tesker, Masha; Engelberg, David

2015-01-01

Transcription factors are commonly activated by signal transduction cascades and induce expression of many genes. They therefore play critical roles in determining the cell's fate. The yeast Hog1 MAP kinase pathway is believed to control the transcription of hundreds of genes via several transcription factors. To identify the bona fide target genes of Hog1, we inducibly expressed the spontaneously active variant Hog1D170A+F318L in cells lacking the Hog1 activator Pbs2. This system allowed monitoring the effects of Hog1 by itself. Expression of Hog1D170A+F318L in pbs2∆ cells imposed induction of just 105 and suppression of only 26 transcripts by at least twofold. We looked for the Hog1-responsive element within the promoter of the most highly induced gene, STL1 (88-fold). A novel Hog1 responsive element (HoRE) was identified and shown to be the direct target of the transcription factor Hot1. Unexpectedly, we could not find this HoRE in any other yeast promoter. In addition, the only gene whose expression was abolished in hot1∆ cells was STL1. Thus Hot1 is essential for transcription of just one gene, STL1. Hot1 may represent a class of transcription factors that are essential for transcription of a very few genes or even just one. PMID:25904326

Assessment of glutathione levels in model solution and grape ferments supplemented with glutathione-enriched inactive dry yeast preparations using a novel UPLC-MS/MS method.

PubMed

Kritzinger, E C; Stander, M A; Du Toit, W J

2013-01-01

A novel, robust and fast ultra-high performance liquid chromatography-MS method has been developed for the simultaneous quantification of reduced glutathione (GSH) and oxidised glutathione (GSSG) in grape juice, wine and model wine solution. Sample preparation is minimal and does not require derivatisation. The method has very good performance in terms of sensitivity and selectivity. The limit of detection was 0.002 and 0.001 mg L(-1) for GSH and GSSG, respectively. The amount of GSH and GSSG released by commercial glutathione-enriched inactivated dry yeast preparations (GSH-IDYs) into a model solution was assessed. Significant differences in the amount of GSH and/or GSSG released into a model wine by different GSH-IDYs were observed, with ethanol influencing this release under certain conditions. The GSH and GSSG levels in grape juice fermentations supplemented with GSH-IDY were also assessed in relation to different addition times during fermentation. GSH-IDY addition can lead to elevated wine GSH levels, provided the supplementation is done early during alcoholic fermentation.

The radiation resistance and cobalt biosorption activity of yeast strains isolated from the Lanyu low-level radioactive waste repository in Taiwan.

PubMed

Li, Chia-Chin; Chung, Hsiao-Ping; Wen, Hsiao-Wei; Chang, Ching-Tu; Wang, Ya-Ting; Chou, Fong-In

2015-08-01

The ubiquitous nature of microbes has made them the pioneers in radionuclides adsorption and transport. In this study, the radiation resistance and nuclide biosorption capacity of microbes isolated from the Lanyu low-level radioactive waste (LLRW) repository in Taiwan was assessed, the evaluation of the possibility of using the isolated strain as biosorbents for (60)Co and Co (II) from contaminated aqueous solution and the potential impact on radionuclides release. The microbial content of solidified waste and broken fragments of containers at the Lanyu LLRW repository reached 10(5) CFU/g. Two yeast strains, Candida guilliermondii (CT1) and Rhodotorula calyptogenae (RT1) were isolated. The radiation dose necessary to reduce the microbial count by one log cycle of CT1 and RT1 was 2.1 and 0.8 kGy, respectively. Both CT1 and RT1 can grow under a radiation field with dose rate of 6.8 Gy/h, about 100 times higher than that on the surface of the LLRW container in Lanyu repository. CT1 and RT1 had the maximum (60)Co biosorption efficiency of 99.7 ± 0.1% and 98.3 ± 0.2%, respectively in (60)Co aqueous solution (700 Bq/mL), and the (60)Co could stably retained for more than 30 days in CT 1. Nearly all of the Co was absorbed and reached equilibrium within 1 h by CT1 and RT1 in the 10 μg/g Co (II) aqueous solution. Biosorption efficiency test showed almost all of the Co (II) was adsorbed by CT1 in 20 μg/g Co (II) aqueous solution, the efficiency of biosorption by RT1 in 10 μg/g of Co (II) was lower. The maximum Co (II) sorption capacity of CT1 and RT1 was 5324.0 ± 349.0 μg/g (dry wt) and 3737.6 ± 86.5 μg/g (dry wt), respectively, in the 20 μg/g Co (II) aqueous solution. Experimental results show that microbial activity was high in the Lanyu LLRW repository in Taiwan. Two isolated yeast strains, CT1 and RT1 have high potential for use as biosorbents for (60)Co and Co (II) from contaminated aqueous solution, on the other hand, but may have the

Activation of the yeast Hippo pathway by phosphorylation-dependent assembly of signaling complexes.

PubMed

Rock, Jeremy M; Lim, Daniel; Stach, Lasse; Ogrodowicz, Roksana W; Keck, Jamie M; Jones, Michele H; Wong, Catherine C L; Yates, John R; Winey, Mark; Smerdon, Stephen J; Yaffe, Michael B; Amon, Angelika

2013-05-17

Scaffold-assisted signaling cascades guide cellular decision-making. In budding yeast, one such signal transduction pathway called the mitotic exit network (MEN) governs the transition from mitosis to the G1 phase of the cell cycle. The MEN is conserved and in metazoans is known as the Hippo tumor-suppressor pathway. We found that signaling through the MEN kinase cascade was mediated by an unusual two-step process. The MEN kinase Cdc15 first phosphorylated the scaffold Nud1. This created a phospho-docking site on Nud1, to which the effector kinase complex Dbf2-Mob1 bound through a phosphoserine-threonine binding domain, in order to be activated by Cdc15. This mechanism of pathway activation has implications for signal transmission through other kinase cascades and might represent a general principle in scaffold-assisted signaling.

Functional mapping of yeast genomes by saturated transposition

PubMed Central

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

2017-01-01

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

High intracellular trehalase activity prevents the storage of trehalose in the yeast Dekkera bruxellensis.

PubMed

Leite, F C B; Leite, D V da R; Pereira, L F; de Barros Pita, W; de Morais, M A

2016-09-01

Dekkera bruxellensis hit the spotlight in the past decade mostly due to its rather high ability to adapt to several different fermentation processes. This yeast relies on different genetic and physiological aspects to achieve and preserve its high industrial fitness and some of these traits are shared with Saccharomyces cerevisiae. We have previously described that D. bruxellensis is unable to make use of accumulating trehalose as a strategy for cell adaptation and survival in the industrial scenario, as opposed to S. cerevisiae. Since trehalose is often involved in mechanisms related to cell protection, we aimed to investigate both cause and effect of the absence of this metabolite in the cell adaptive capacity in the industrial environment. Our results indicate that the major cause for the nonaccumulation of trehalose is the high constitutive activity of neutral trehalase. Therefore, the rate of trehalose degradation could be higher than its rate of synthesis, preventing accumulation. Altogether, our data elucidate the mechanisms involved in the lack of trehalose accumulation in D. bruxellensis as well as evaluates the implications of this feature. Dekkera bruxellensis can successfully take advantage of its peculiar physiological and genetic traits in order to adapt and survive in fermentation processes. So far, tolerance to stress has been credited to trehalose synthesis. The data presented in this work provided information on the underlying mechanism that prevents trehalose accumulation and corroborated the recent information that trehalose itself is not implicated in yeast stress tolerance. Second, it showed that D. bruxellensis responds differently to Saccharomyces cerevisiae to excess of sugar, which may explain its preference for respiration (oxidative metabolism) over fermentation (reductive metabolism) even at limited oxygen supply. These findings help to understand the drop on ethanol production in processes overtaken by this yeast. © 2016 The

Identification and assessment of kefir yeast potential for sugar/ethanol-resistance

PubMed Central

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

2013-01-01

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

Isolation of Yeasts from Guajillo Pepper (Capsicum annuum L.) Fermentation and Study of Some Probiotic Characteristics.

PubMed

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

2018-04-25

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

Marine yeast isolation and industrial application.

PubMed

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

2014-09-01

Over the last century, terrestrial yeasts have been widely used in various industries, such as baking, brewing, wine, bioethanol and pharmaceutical protein production. However, only little attention has been given to marine yeasts. Recent research showed that marine yeasts have several unique and promising features over the terrestrial yeasts, for example higher osmosis tolerance, higher special chemical productivity and production of industrial enzymes. These indicate that marine yeasts have great potential to be applied in various industries. This review gathers the most recent techniques used for marine yeast isolation as well as the latest applications of marine yeast in bioethanol, pharmaceutical and enzyme production fields. © 2014 The Authors FEMS Yeast Research published by John Wiley & Sons Ltd on behalf of Federation of European Microbiological Societies.

Assessment of dioxin-like activity in ambient air particulate matter using recombinant yeast assays

NASA Astrophysics Data System (ADS)

Olivares, Alba; van Drooge, Barend L.; Pérez Ballesta, Pascual; Grimalt, Joan O.; Piña, Benjamin

2011-01-01

Ectopic activation of the aryl hydrocarbon receptor (AhR), also known as dioxin-like activity, is a major component of the toxicity associated with polycyclic aromatic hydrocarbons (PAH). Filtration of ambient air particulate matter through PM 10 filters followed by chemical determination of PAH concentrations and a yeast-based bioassay (RYA) were combined to evaluate and characterize dioxin-like activity in ambient air. Samples were collected in a semirural area of Northern Italy between September 2008 and February 2009. Total PAH contents ranged between 0.3 ng m -3 and 34 ng m -3 and were in correlation with seasonal variations of meteorological conditions and combustion processes. Dioxin-like activity values in air samples showed an excellent correlation (0.71 < R2 < 0.86) with the observed PAH concentrations and the predicted toxicity equivalents for PAH. This RYA-bioassay reported in the present study provides a simple and low-cost routine control for toxic PAH emissions, even at background air concentration levels.

Yeast ecology of Kombucha fermentation.

PubMed

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

2004-09-01

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

The Fermentative and Aromatic Ability of Kloeckera and Hanseniaspora Yeasts

NASA Astrophysics Data System (ADS)

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

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

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

PubMed

Shima, Jun; Ando, Akira; Takagi, Hiroshi

2008-03-01

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

A Photometer for Measuring Population Growth in Yeast.

ERIC Educational Resources Information Center

Tatina, Robert; Hartley, Tamela; Thomas, Danita

1999-01-01

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

Marine yeast isolation and industrial application

PubMed Central

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

2014-01-01

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

Effects of drying on nitrification activity in zeoponic medium used for long-term space missions

NASA Technical Reports Server (NTRS)

McGilloway, R. L.; Weaver, R. W.

2004-01-01

One component of a proposed life support system is the use of zeoponic substrates, which slowly release NH4+ into "soil" solution, for the production of plants. Nitrifying bacteria that convert NH4+ to NO3- are among the important microbial components of these systems. Survival of nitrifying bacteria in dry zeoponic substrates is needed, because the substrate would likely be stored in an air-dry state between croppings. Substrate was enriched for nitrifying bacteria and allowed to air-dry in a laminar flow hood. Stored substrate was analyzed for nitrifier survivability by measuring nitrifier activity at the beginning, 3 days, 1, 2, and 3 weeks. After rewetting, activity was approximately 9 micrograms N g-1 h-1 regardless of storage time. Nitrification rates did not decrease during storage. It seems unlikely that drying between plantings would result in practical reductions in nitrification, and reinoculation with nitrifying bacteria would not be necessary.

Light-mediated control of DNA transcription in yeast

PubMed Central

Hughes, Robert M.; Bolger, Steven; Tapadia, Hersh; Tucker, Chandra L.

2012-01-01

A variety of methods exist for inducible control of DNA transcription in yeast. These include the use of native yeast promoters or regulatory elements that are responsive to small molecules such as galactose, methionine, and copper, or engineered systems that allow regulation by orthogonal small molecules such as estrogen. While chemically regulated systems are easy to use and can yield high levels of protein expression, they often provide imprecise control over protein levels. Moreover, chemically regulated systems can affect many other proteins and pathways in yeast, activating signaling pathways or physiological responses. Here, we describe several methods for light mediated control of DNA transcription in vivo in yeast. We describe methodology for using a red light and phytochrome dependent system to induce transcription of genes under GAL1 promoter control, as well as blue light / cryptochrome dependent systems to control transcription of genes under GAL1 promoter or LexA operator control. Light is dose dependent, inexpensive to apply, easily delivered, and does not interfere with cellular pathways, and thus has significant advantages over chemical systems. PMID:22922268

Yeast as factory and factotum.

PubMed

Dixon, B

2000-02-01

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

Water quality and diversity of yeasts from tropical lakes and rivers from the Rio Doce basin in Southeastern Brazil

PubMed Central

Medeiros, Adriana O.; Missagia, Beatriz S.; Brandão, Luciana R.; Callisto, Marcos; Barbosa, Francisco A. R.; Rosa, Carlos A.

2012-01-01

Yeast communities were assessed in 14 rivers and four lakes from the Doce River basin in Brazil, during the rainy and dry seasons of the years 2000 and 2001. Water samples were collected at the subsurface in all sites. The following physical and chemical parameters were measured: temperature, dissolved oxygen, pH, electrical conductivity, total phosphorus, ortho-phosphate, ammonium, nitrate, nitrite and total nitrogen and the counts of faecal coliforms and heterotrophic bacteria were carried out to characterize the aquatic environmental sampled. The yeast counts were higher in aquatic environments with the highest counts of coliform and heterotrophic bacteria. These environments receive a high influx of domestic and industrial waste. A total of 317 isolates identified in forty eight yeast species were recorded in the sites sampled and the specie Aureobasidium pullulans were found in eleven out of eighteen sites sampled and some opportunistic pathogens such as the yeast species Candida krusei were isolated only in the polluted rivers with a positive correlation with the biotic and abiotic parameters that indicate sewage contamination. PMID:24031990

Occurrence of mycotoxins and yeasts and moulds identification in corn silages in tropical climate.

PubMed

Carvalho, B F; Ávila, C L S; Krempser, P M; Batista, L R; Pereira, M N; Schwan, R F

2016-05-01

This study was aimed to identify yeasts and moulds as well as to detect mycotoxin in corn silages in southern Minas Gerais, Brazil. Corn silages from 36 farms were sampled to analyse dry matter, crude protein, ether extract, ash, neutral detergent fibre, nonfibre carbohydrates and mycotoxins contents, yeasts and moulds population, pH and temperature values. The mycotoxins found in high frequency were aflatoxin in 77·7% of analysed samples, ochratoxin (33·3%) and zearalenone (22·2%). There was no significant correlation between the mycotoxin concentration and the presence of moulds. The pH was negatively correlated with ochratoxin concentration. Aspergillus fumigatus was identified in all silages that presented growth of moulds. Ten different yeast species were identified using the culture-dependent method: Candida diversa, Candida ethanolica, Candida rugosa, Issatchenkia orientalis, Kluyveromyces marxianus, Pichia manshurica, Pichia membranifaciens, Saccharomyces cerevisiae, Trichosporon asahii and Trichosporon japonicum. Another six different yeast species were identified using the culture-independent method. A high mycotoxin contamination rate (91·6% of the analysed silages) was observed. The results indicated that conventional culturing and PCR-DGGE should be combined to optimally describe the microbiota associated with corn silage. This study provides information about the corn silage fermentation dynamics and our findings are relevant to optimization of this silage fermentation. © 2016 The Society for Applied Microbiology.

Cachaça yeast strains: alternative starters to produce beer and bioethanol.

PubMed

Araújo, Thalita Macedo; Souza, Magalhães Teixeira; Diniz, Raphael Hermano Santos; Yamakawa, Celina Kiyomi; Soares, Lauren Bergmann; Lenczak, Jaciane Lutz; de Castro Oliveira, Juliana Velasco; Goldman, Gustavo Henrique; Barbosa, Edilene Alves; Campos, Anna Clara Silva; Castro, Ieso Miranda; Brandão, Rogelio Lopes

2018-04-16

This work was performed to verify the potential of yeast strains isolated from cachaça distilleries for two specific biotechnological applications: beer and bioethanol production. In the beer production, the strains were tested for characteristics required in brewery practices, such as: capacity to ferment maltose and maltotriose, ability to grow at lowest temperatures, low H 2 S production, and flocculation profile. Among the strains tested, two of them showed appropriate characteristics to produce two different beer styles: lager and ale. Moreover, both strains were tested for cachaça production and the results confirmed the capacity of these strains to improve the quality of cachaça. In the bioethanol production, the fermentation process was performed similarly to that used by bioethanol industries: recycling of yeast biomass in the fermentative process with sulfuric acid washings (pH 2.0). The production of ethanol, glycerol, organic acids, dry cell weight, carbohydrate consumption, and cellular viability were analyzed. One strain presented fermentative parameters similar to PE2, industrial/commercial strain, with equivalent ethanol yields and cellular viability during all fermentative cycles. This work demonstrates that cachaça distilleries seem to be an interesting environment to select new yeast strains to be used in biotechnology applications as beer and bioethanol production.

Drying kinetics of onion ( Allium cepa L.) slices with convective and microwave drying

NASA Astrophysics Data System (ADS)

Demiray, Engin; Seker, Anıl; Tulek, Yahya

2017-05-01

Onion slices were dried using two different drying techniques, convective and microwave drying. Convective drying treatments were carried out at different temperatures (50, 60 and 70 °C). Three different microwave output powers 328, 447 and 557 W were used in microwave drying. In convective drying, effective moisture diffusivity was estimated to be between 3.49 × 10-8 and 9.44 × 10-8 m2 s-1 within the temperature range studied. The effect of temperature on the diffusivity was described by the Arrhenius equation with an activation energy of 45.60 kJ mol-1. At increasing microwave power values, the effective moisture diffusivity values ranged from 2.59 × 10-7 and 5.08 × 10-8 m2 s-1. The activation energy for microwave drying of samples was calculated using an exponential expression based on Arrhenius equation. Among of the models proposed, Page's model gave a better fit for all drying conditions used.

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

PubMed

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.

Digestion of Yeasts and Beta-1,3-Glucanases in Mosquito Larvae: Physiological and Biochemical Considerations.

PubMed

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

2016-01-01

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