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PubMed2000

Application of yeast enolase as antigen for immunodiagnosis of malaria.

In 1998, we reported that Plasmodium falciparum (Pf) enolase was useful as the capture antigen for the immunodiagnosis of malaria. In the present study, we modified a fluorescence-ELISA for the diagnosis of malaria by applying yeast enolase or rabbit muscle enolase as antigen. Sera from 67 falciparum malaria patients and 15 vivax malaria patients were tested by the method. Positivity rates of the former was 82.1% against yeast enolase antigen and 90.5% against rabbit muscle enolase antigen, and those of latter was 93.3% against both enolase antigens. Mean antibody level (RFU values) of sera from falciparum and vivax malaria patients were significantly higher than those from healthy individuals. There was a significant correlation between anti-yeast and anti-rabbit muscle enolase antibody level (RFU values) in the group of falciparum subjects (r = 0.401, p<0.001). A significant correlation between RFU values against yeast enolase antigen and indirect fluorescent antibody titers against crude Pf antigen in the same subjects was recognized (r = 0.518, p<0.001). Longitudinal changes of RFU values against yeast enolase for the following 4 weeks after admission were also examined for sera from falciparum malaria patients. Patients with more severe malaria showed increasing RFU values as the clinical courses progressed. However, in the mild cases, each RFU value stayed unchanged during the course. We concluded that yeast and rabbit muscle enolase could be appropriately used as antigen for the immunodiagnosis of malaria.

Animals↗

PubMed2000

[Technology for the whole utilization of brewer's yeast in food industry].

A flexible scheme for the fractionation of brewer's yeast was developed. The procedure allows the production of different products such as: dry yeast flakes, dry yeast pills, yeast-extract based table sauce, yeast protein concentrates and soy-like sauce. The investment required for the processing of one ton per day is below 2 million dollars with an overall profitability higher than 53%. Investment is recovered in 0.75 years. The production of food ingredients from yeast upgrades its biomass about 25 fold. Present procedure is compared with other biomass fractionation processes taking into account the utilization of all technological streams where the process becomes environmentally friendly since effluent production significantly lower than similar technologies.

Analysis of Variance↗

PubMedDate not supplied

[Effect of cytochrome oxidase inhibitors on the yeast thermotolerance].

The investigation of the effect of the cytochrome oxidase inhibitors sodium cyanide and sodium azide on the thermotolerance of the yeasts Rhodotorula rubra, Debaryomyces vanriji, and Saccharomyces cerevisiae showed that these inhibitors diminish the thermotolerance of R. rubra and D. vanriji, but do not affect the thermotolerance of S. cerevisiae. Taking into account the fact that, unlike the latter yeast, R. rubra and D. vanriji are nonfermentative yeasts, the difference in the effects of the inhibitors on the yeast thermotolerance can be readily explained by the different types of glucose utilization (either oxidative or fermentative) in these yeasts. The data obtained also provide evidence that there is a correlation between the functional activity of mitochondria and the thermotolerance of yeast cells.

Adaptation, Physiological↗

PubMed2003

Screening of augmenter of liver regeneration-binding proteins by yeast-two hybrid technique.

OBJECTIVE: To investigate the biological function of augmenter of liver regeneration (ALR), we used yeast-two hybrid technique to detect proteins in hepatocytes interacting with ALR. METHODS: ALR bait plasmid was constructed by using yeast-two hybrid system 3, then transformed into yeast AH109. The transformed yeast was mated with yeast Y187 containing liver cDNA library plasmid in a 2XYPDA medium. Diploid yeast was plated on a synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) containing x-alpha-gal for selection and screening. After extracting and sequencing of the plasmid from blue colonies. Analysis was performed by bioinformatics. RESULTS: Of 36 colonies sequenced, 14 are metallothionein, 12 albumin, and 3 selenoprotein P. One colony is a new gene with unknown function. CONCLUSION: The successful cloning of gene of ALR interacting protein has paved the way for studying the physiological function of ALR and associated proteins.

Animals↗

PubMedDate not supplied

[Yeasts--biosorbents of heavy metals].

The sharp increase of the level of environment pollution by heavy metals caused the increase of interest to the problem of live organisms (including microorganisms) resistance to these metals. Biosorption is one of the mechanisms of microorganisms resistance to heavy metals. Yeasts as biosorbents are of special interest. An analysis of the data from literature have shown that the yeast biomass may be used successfully as biosorption material for such metals as Ag, Au, Cd, Co, Cr, Cu, Ni, Pb, U, Th, Zn. Yeasts of genera Saccharomyces, Candida, Pichia are efficient biosorbents of metals. The sorptional system estimation is based on the classic sorption isotherm obtained in the course of equilibrium experiments and depends on pH, properties of metal ions, biomass concentration, preliminary physical or chemical treatment of the biomass, presence of various organic and inorganic ions and on temperature. The yeast biomass may be obtained using numerous industrial processes, that decreases considerably the biosorbent cost. Most yeasts can sorb a wide range of metals or be strictly specific in respect of only one metal. Special attention would be paid to the cell wall which structure determines sorption proceeding mechanisms. Problems of mechanisms of heavy metal biosorption by microorganisms at molecular level are discussed. The review also deals with the newest developments on improving the biosorption processes in microorganisms, yeast in particular.

Biodegradation, Environmental↗

PubMed2004

[Construction and confirmation of the fused plasmid with Rb bait gene in yeast two-hybrid system].

OBJECTIVE: To screen and clone the novel genes related to cellular proliferation of oral squamous cell carcinoma. METHODS: We selected the Rb gene as the bait protein gene to construct the fusion bait plasmid of yeast two-hybrid. The whole code sequence of Rb gene was acquired by digestion with restricted enzyme EcoRI and BamH1 and reclaimed from its original vector pGBT9-pRb. After being confirmed by electrophoresis, the Rb gene was cloned into the MCS of the plasmid pGBKT7 to construct a recombined plasmid pGBKT7-pRb and the sequence of the recombined plasmid was detected in company. According to the protocol of yeast two hybrid system III, the competent Y187 yeast was prepared, and transformed with recombined plasmid pGBKT7-pRb. Following that, the toxicity and transcriptional activation of this recombined plasmid pGBKT7-pRb in Y187 yeast were tested. RESULTS: The sequence of the recombined plasmid was correct compared with the sequence provided in Genbank. The protein could be correctly synthesized in vitro, and no self-activating transcriptional activation and toxicity was observed in Y187 yeast. CONCLUSIONS: The construction of the recombined plasmid was capable to be used as the fusion bait plasmid in yeast two-hybrid system III, and the recombined Rb-protein could be used as the bait protein successfully.

Carcinoma, Squamous Cell↗

PubMedDate not supplied

[Seasonal dynamics in a yeast population on the Oxalis acetosella L. leaves].

Analysis of an epiphytic yeast population on the leaves of the evergreen common wood sorrel Oxalis acetosella L. throughout a year showed that the density and the species composition of this population underwent regular seasonal changes. There were almost no yeasts on the young spring leaves. However, the yeast population on the mature leaves tended to increase in the autumn, reaching a maximum after the formation of continuous snow cover. Then the yeast population on the leaves tended to decrease, reaching a minimum in the spring. The species diversity of the yeasts was maximum in the autumn. The population of the epiphytic yeast species Cystofilobasidium capitatum, Rhodotorula fujisanensis, Leucosporium scottii, and Cryptococcus flavus peaked in the autumn. On the other hand, the population of the widespread epiphytic species Cryptococcus laurentii on the wood sorrel leaves peaked in January. The relative abundance of the red-pigmented phytobionts Rhodotorula glutinis and Sporobolomyces roseus virtually did not change throughout the year. The relative abundance of the euribiotic species Cryptococcus albidus showed irregular monthly variations. The data obtained show that the epiphytic microbial population of various plants can be comprehensively studied only by analyzing this population throughout the vegetative period of the plants.

Colony Count, Microbial↗

PubMedDate not supplied

[Community structure of yeast fungi in forest biogeocenoses].

The results of longstanding studies of yeasts inhabiting soil, plant surface, and plant residues in typical subboreal forests of the European part of Russia are summarized. The abundance and species diversity of yeast communities in the array of substrates corresponding to succession stages in plant residues decomposition are shown to steadily decline. Each stage is characterized by its specific set of dominating species. The yeast diversity in forest biogeocenoses is shown to surpass that in other geographic zones. This manifests itself in a greater number of species occurring in similar arrays of substrates, in the absence of conspicuous dominants on the biogeocenotic level, and in a higher differentiation of the yeast population with respect to its habitat type. The forest yeast populations are also characterized by high diversity of yeasts of ascomycetous affinity and of the anamorphic stages of Taphrinales and Tremellales, as well as by the presence of typical pedobiont species (except Lipomyces spp.).

Ecosystem↗

PubMed2005

[Screening ubiquitin/ribosomal protein S27a by yeast two-hybridization system].

BACKGROUND & OBJECTIVE: Protein kinase CK2, a kind of ubiquitous eukaryotic messenger-independent protein serine/threonine kinase, plays a vital role in cell differentiation and proliferation, signal transduction and procession. Activity of CK2 in hematopoietic cells is 2-8 folds higher than that in relevant normal tissues, moreover changes of CK2 activity are correlated to tumor growth. In order to investigate the mechanism of its effect on hematopoietic cells, we used yeast two-hybridization screening the proteins interacting with protein kinase CK2alpha' subunit from HL-60 cells cDNA library. METHODS: The target CK2alpha' cDNA was obtained by amplifying recombinant plasmid pTHCK2A', containing human protein kinase CK2alpha' subunit cDNA, through polymerase chain reaction (PCR). Pst I/Nde I-digested PCR products were directionally cloned into DNA-BD vector pGBKT7, which had also been digested by Pst I/Nde I. The recombinant plasmid was named yeast two-hybridization BD bait plasmid, and confirmed by DNA sequencing, and auto-activated experiments. Total RNA of HL-60 cells was extracted, CLONTECH switching mechanism at 5' end of RNA transcript method was used to construct a cDNA library in yeast cells. Library plasmid was named AD plasmid. BD plasmid and AD plasmid were co-transformed into competent yeast AH109. Yeast two-hybridization was used to screen positive clones. RESULTS: Six proteins, interacting with human protein kinase CK2alpha' subunit, were screened. DNA sequencing and homology comparison showed that one of the proteins was highly homologous with ubiquitin/ribosomal protein S27a (99.8%). CONCLUSION: Using yeast two-hybridization system could screen out ubiquitin/ribosomal protein S27a, which may interact with human protein kinase CK2alpha' subunit, from HL-60 cells.

Base Sequence↗

PubMedDate not supplied

[The metabolic efficiency of baker's yeast in an atherogenic diet].

The effect of bakery compressed yeasts in the amounts of 6 and 12 g/100 g of the ration was studied in rats. It was revealed that 12 g of yeasts per 100 g of the atherogenic ration produced a hypocholesterolemic effect. A negative effect of this amount of the yeasts was manifest in the slow growth of the rats' body mass and in an increased ratio of the kidney/body mass. The yeasts amounts used did not protect the test animals from the kidney infiltration with lipids and cholesterol; 12 g of yeasts per 100 g of the ration promoted elevation of sialic acid content in the blood plasma. Morphologic changes were observed only in the aortal wall, they were characteristic of the prelipid stage of atherosclerosis and did not depend on the yeasts amount.

Animals↗

PubMed1989

Yeasts associated with the white shrimp Penaeus schmitti, sediment, and water of Sepetiba Bay, Rio de Janeiro, Brasil.

Samples were collected in a polluted site with mean fecal coliform counts of the water being 9.0 x 10(2)/100 ml and less polluted areas including commercial fishing areas with fecal coliforms typically below 2.0 x 10(1)/100 ml. Yeast populations from the polluted site were 4.6 x 10(2) to 9.2 x 10(3)/g of shrimp intestine, 1.0 x 10(1) to 2.4 x 10(2)/g of sediment and 4.0 x 10(-1) to 4.6 x 10(1)/ml of water, and in the less polluted site 3.0 x 10(1) to 2.3 x 10(2)/g of intestines and 3.0 x 10(-1) to 2.4 x 10(1)/ml of water. About half of these yeast populations were fermentative. Prevalent yeasts isolated from shrimp were Candida famata, Candida intermedia, Candida tropicalis, Candida krusei, Geotrichum sp., Trichosporon sp., Debaryomyces hansenii, Rhodotorula rubra, Kloeckera apiculata, Cryptococcus sp., Hansenula anomala, and Candida spp. The species found in water and sediment were similar to those of shrimp except that C. tropicalis was more prevalent in sediment with 25% of the population and D. hansenii in water with 12%. Yeasts normally associated with warm blooded animals and sewage were predominant in the shrimp from the polluted site, but yeasts from the less polluted site were more typical of clean water. Yeasts were concentrated in the shrimp intestine suggesting that this is a favorable environment for them but no species were found to be selectively associated with this niche.

Animals↗

PubMed1988

Biological function of modified nucleotides in tRNA molecules--synthesis and biological activity of the analogues of yeast alanyl tRNA with I34 replaced by A34 or G34.

Analogues of yeast alanyl tRNA with I34 replaced by A34 or G34 were synthesized. Synthetic analogues of yeast alanyl tRNT occupy the same position as the natural yeast alanyl tRNA on polyacrylamide gel electrophoresis, and their purity is about 95% after electrophoresis on a 10% or 20% polyacrylamide gel. The two terminal and nearest neighbour nucleotides of the analogues are all correct. The accepting activity of the synthetic analogues is similar to that of the reconstituted natural yeast alanyl tRNA. The incorporation activity of alanine into proteins of the synthetic analogues is about 30% of that of the natural of reconstituted natural yeast alanyl tRNA when I34 is replaced by A, and is 90% when I34 is replaced by G. The reason of the variation in biological function of the analogues of yeast alanyl tRNA after I34 replaced by A or G was discussed.

RNA, Fungal↗

PubMed1979

[Contamination of Bulgarian yogurt with yeasts and molds and the dynamics of their development in the product].

Twenty one complex production experiments aiming to establish the sources of Bulgarian yoghourt contamination with yeasts and moulds were carried out. It was established that they enter the product by way of unclean production lines and implements, by the fermenting agent, by the air in the fermentation premises. Their number in the ready product increases during storage. The extent of their increase is in relation with their initial number and with the type of yoghourt cooling and storage. At temperature 8-10 degrees C yeast numbers increase after 6-day storage from 1 500 to 4 000 times, while at temperature 18-25 degrees C even on the 3d day their number surpasses 1-15 millions per g. Moulds appear after 2-4 days of storage at 18-25 degrees C in quantities of 2000-13 000/g, while at 8-10 degrees C--after the 5th day and their number varies from 100 to 2 000/g. Defects in the organoleptic indices of yoghourt (acid-tart yeast taste and "rising") appear in case of accumulation of more than 500 000-1 million yeasts per g. In 3.5% of the 201 lots of yoghourt presented for sale on the market and investigated the presence of yeasts was established, while only one lot had moulds. Standards concerning the permissible yeast and mould content are presented, which guarantee longer periods of preservation time for Bulgarian yoghourt.

Bulgaria↗

PubMed1982

Potentialities of yeasts in production of single-cell proteins (SCP).

Different local active yeasts were isolated from air, soils, and muddy sludges. Potentialities and capabilities of 67 yeasts isolates for formation of SCP (single-cell protein) were evaluated by their cultivation on the fermentation medium, containing diesel oil as sole carbon source to select the most efficient yeast isolates. Identification of the most active organisms revealed that Candida tropicalis and Yarrowia lipolytica were the most efficient yeasts, having potentialities for SCP production. Biochemical changes which occurred during the fermentative production of SCP by Candida tropicalis revealed that during the fermentation process a deep in pH towards the acid side was recorded, and this might be due to the formation of certain organic acids with the beginning of fermentation. Yields of yeast cell biomass increased with the increase of fermentation period, reaching its optimum at 168 h, above which a decline in SCP was observed. High diesel oil concentrations in the fermentation medium harmed yeast growth and consequently a decrease in cell biomass was observed, while low diesel oil concentrations, especially in the range of 40--60 ml/litre, gave high titres of SCP. Addition of diesel oil at different intervals of the fermentation process-promoted yield of SCP.

Candida↗

PubMed1976

Evaluation of a multitest microtechnique for yeast identification.

A new, multitest, microtechnique system, API 20C (Analytab Products Inc. Clinical Yeast System), was evaluated by comparing it to the U.S. Center for Disease Control (CDC) standard techniques for the identification of yeast. Forty-four yeast strains isolated from clinical specimens were tested by fermentation and assimilation. Six fermentation carbohydrates and ten assimilation carbohydrates were compared. API results were read after incubation of 24 and 48 hours while the standard CDC system was read after 48 hours and 14 days when needed. One hundred per cent agreement in identification was found between the two systems in the strains studied. Growth in the presence of actidione was tested by the API strip only and gave unreliable results with nine per cent of the strains tested. The API 20 Clinical Yeast System provides a reliable and rapid approach to yeast identification enabling the clinical laboratory to completely identify a yeast organism in 48 hours instead of the usual four to 14 days. A cost comparison showed the API system to be significantly more economical than the conventional method of identification.

Culture Media↗

PubMed2025

Genome-based exploration of volatile flavor diversity from food yeast species.

Yeast shares a longer than 10 000-year history with humans in food fermentation by producing various volatile flavor compounds that contribute to the final taste and aroma of foods. Yeast-associated volatile flavor compounds include esters, benzenoids, sulfur compounds, and phenolic derivatives, which enhance the sensory complexity of fermented foods and beverages. Genome-scale technologies have advanced and transformed our understanding of the genetic and evolutionary drivers of volatile flavor diversity. The conventional approach to aroma enrichment and flavor balancing through single-strain optimization has been redefined through yeast cofermentation strategies, such as the pairing of Saccharomyces cerevisiae with nonconventional yeast species. This minireview summarizes the latest genomic insights into volatile flavor compound formation through ester, benzenoid, sulfur, and phenolic pathways in various yeast species and highlights the shaping of the next generation of food fermentation innovation via cofermentation combined with omics analysis, followed by a future perspective on synthetic biology for industrial applicability.

Volatile Organic Compounds↗

PubMed1996

A rapid and selective assay for measuring cell surface hydrophobicity of brewer's yeast cells.

A rapid and selective assay was developed to measure cell surface hydrophobicity of brewer's yeast cells. During this so-called magnobead assay, bottom-fermenting yeast cells adhere to paramagnetic, polystyrene-coated latex beads which can easily be removed from the cell suspension by using a (samarium-cobalt) magnet. At pH 4 center dot 5, electrostatic repulsion between yeast cells and latex beads was found to be minimal and yeast cell adhesion was predominantly based on hydrophobic interactions. The percentage of cells adhering to the beads could be calculated and provided a measure for cell surface hydrophobicity. Cell surface hydrophobicity measured by the magnobead assay was found to yield similar results, as did determination of contact angles of water droplets on a layer of yeast cells, a standard method for measuring surface hydrophobicity. However, the magnobead assay has the following advantages: (i) it is a quick and simple method, and, more significantly, (ii) hydrophobicity can be measured under physiological conditions. Use of the magnobead assay confirmed that a higher level of cell surface hydrophobicity is correlated with stronger flocculence of brewer's lager yeast cells.

Adhesiveness↗

PubMed1996

Review: to bud until death: the genetics of ageing in the yeast, Saccharomyces.

Individual cells of the budding yeast, Saccharomyces cerevisiae, have a limited division capacity and undergo characteristic changes as they senesce, primarily increasing both their cell size and cell cycle time. The mortality curve for ageing yeast cells can be described by the Gompertz equation, the classical definition for an ageing population. Recent work from several laboratories has demonstrated that genes can determine the yeast lifespan. Studies with the UTH genes have implicated changes in transcriptional silencing during yeast ageing, but the roles of the RAS2, LAG1 and PHB1 genes in regulating yeast longevity are still unclear. What is becoming clearer, however, is that yeast ageing is more than just a bud scar phenomenon.

Cell Division↗