Brewer's yeast and sugarcane yeast as protein sources for dogs

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ultrasonic waves: Bioeffects on yeast cells

Applications of ultrasound were starting from 1912 with the primary objective the detection of icebergs on prevention of maritime accidents. Algae, fish deaths and destruction were observed in the vicinity of sonar that equipped ships and submarines during the First World War.The evolutions of research and studies with ultrasound have big advances following the discovery of piezoelectric transducers in science and technology. As an example we can mention its application in microsurgery, fatigue detection in aerospace mechanics, catalysis sonochemical, biotechnology and others.The work presented here aims to demonstrate the application of ultrasonic in pulsed mode beams in biotechnology with the aim of improving the fermentation of a culture broth containing biological agents. In these experiments we used as ultrasound equipment and oscilator Sonics VCX-600 (20KHz), probe type wave guide. The experiments were conducted in a glass reactor of 200 mL of biomaterial containing cane juice and Saccharomyces cerevisiae in suspension. The parameters analyzed were related to the content Alcohlic (FID gas chromatography), and cell viability (Neubauer chamber), TRS (refractometry). Analysis of results showed that the total production exceeded in irradiated samples compared to normal fermentation (without ultrasound), suggesting additional advantage of ultrasound activation. Lastin Trials 1400 min, showed ethanol production systems 12% more than non-enabled systems. In this context alternatives for ethanol production, bio fuel and many other byproducts of the alcohol industries and chemicals could benefit from the use of ultrasound beams in this range of frequencies.

Mathematical modeling of a continuous alcoholic fermentation process in a two-stage tower reactor cascade with flocculating yeast recycle

Experiments of continuous alcoholic fermentation of sugarcane juice with flocculating yeast recycle were conducted in a system of two 0.22-L tower bioreactors in series, operated at a range of dilution rates (D (1) = D (2) = 0.27-0.95 h(-1)), constant recycle ratio (alpha = F (R) /F = 4.0) and a sugar concentration in the feed stream (S (0)) around 150 g/L. The data obtained in these experimental conditions were used to adjust the parameters of a mathematical model previously developed for the single-stage process. This model considers each of the tower bioreactors as a perfectly mixed continuous reactor and the kinetics of cell growth and product formation takes into account the limitation by substrate and the inhibition by ethanol and biomass, as well as the substrate consumption for cellular maintenance. The model predictions agreed satisfactorily with the measurements taken in both stages of the cascade. The major differences with respect to the kinetic parameters previously estimated for a single-stage system were observed for the maximum specific growth rate, for the inhibition constants of cell growth and for the specific rate of substrate consumption for cell maintenance. Mathematical models were validated and used to simulate alternative operating conditions as well as to analyze the performance of the two-stage process against that of the single-stage process.

Energy values of traditional ingredients and sugarcane yeast for laying hens

An experiment was conducted to determine the chemical composition and apparent metabolizable energy (AME) and apparent metabolizable energy corrected for nitrogen balance (AMEn) values of corn, soybean meal (SBM), soybean oil (SO) and sugarcane yeast (SY) (Saccharomyces cerevisiae). A metabolism trial was performed with 120 Dekalb White laying hens at 65 weeks of age, using the method of total excreta collection. Birds were housed in metabolism cages and distributed according to a completely randomized design into five treatments with, six replicates of four birds each. The experimental period consisted of four days of adaptation and four days of excreta collection. The experimental diets included: a reference diet based on corn and SBM and four test diets containing 40% corn, 30% SBM, 10% SO or 30 % SY. The chemical compositions of the tested ingredients, expressed on "as-is" basis were: 86.9, 87.29, 87.32 and 99.5% dry matter; and 3.51, 2.08, 99.31 and 0.03 ether extract for corn, SBM, SO and SY, respectively. Corn, SBM, and SO presented 7.33, 43.61 and 24.64% crude protein, and 0.58, 5.07 and 6.77% ash, respectively; and crude fiber contents of corn and SBM were, respectively, 2.24% and 3.56%. The following AME and AMEn (kcal/kg dry matter) values were obtained: 3,801 and 3,760 kcal/kg for corn, 2,640 and 2,557 kcal/kg for SBM, 8,952 and 8,866 kcal/kg for SO, and 1,023 and 925 kcal/kg for sugarcane yeast, respectively.

Production, purification, and characterization of an extracellular acid protease from the marine Antarctic yeast Rhodotorula mucilaginosa L7

The production, purification, and characterization of an extracellular protease released by Rhodotorula mucilaginosa L7 were evaluated in this study. This strain was isolated from an Antarctic marine alga and previously selected among others based on the capacity to produce the highest extracellular proteolytic activity in preliminary tests. R. mucilaginosa L7 was grown in Saboraud-dextrose medium at 25 °C, and the cell growth, pH of the medium, extracellular protease production and the glucose and protein consumption were determined as a function of time. The protease was then purified, and the effects of pH, temperature, and salt concentration on the catalytic activity and enzyme stability were determined. Enzyme production started at the beginning of the exponential phase of growth and reached a maximum after 48 h, which was accompanied by a decrease in the pH as well as reductions of the protein and glucose concentrations in the medium. The purified protease presented optimal catalytic activity at pH 5.0 and 50 °C. Finally, the enzyme was stable in the presence of high concentrations of NaCl. These characteristics are of interest for future studies and may lead to potential biotechnological applications that require enzyme activity and stability under acidic conditions and/or high salt concentrations.

In situ selective determination of methylmercury in river water by diffusive gradient in thin films technique (DGT) using baker's yeast (Saccharomyces cerevisiae) immobilized in agarose gel as binding phase

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Yamadazyma riverae sp. nov., a yeast species isolated from plant materials

Nine strains of a novel yeast species were isolated from rotting wood, tree bark, ant nests or living as endophytes in leaves of Vellozia gigantea. Analysis of the sequences of the internal transcribed spacer (ITS) region and the D1/D2 domains of the large subunit rRNA gene showed that this species is related to Candida insectorum in the Yamadazyma clade. The new species differs from its closely related species by 10 and 11 substitutions in the ITS region and the D1/D2 domains of the large subunit of the rRNA gene, respectively. The species is heterothallic and forms asci with one to two hat-shaped ascospores. The name Yamadazyma riverae sp. nov. is proposed. The type strain of Yamadazyma riverae sp. nov. is UFMG-CM-Y444T (= CBS 14121) and the allotype strain is TT12 (= CBS 14098 = UFMG-CM-Y577). The Mycobank number is MB 813221.

Yeast CA-11 fermentation in musts treated with brown and green propolis

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Improvement of the alcohol dehydrogenase from baker's yeast using polymers and salts for alcohol determinations in beverages

An alcohol dehydrogenase (ADH) was purified from dry baker’s yeast. This is a key enzyme of the primary short-chain alcohol metabolism in many organisms. In the present study, the obtained enzymatic preparation of baker’s yeast, containing 2.7 U/mg of ADH, was used in the reactions. The purified extract of the ADH obtained from Fermix commercial dry yeast, presented the highest activity and purification factor when ammonium sulfate was added in the precipitation of protein, in the range 35-60% (w/v). The enzymatic preparation was maintained for 2 months in the lyophilized form at 4ºC (retention of 96.2% of activity) in the presence of 1 mmol/L of sodium azide, and it maintained 47% of activity for 30 days at 30°C in the presence of 15% PEG. The assays of ethanol (detection range 5 mM -150 mM or 2.3 x 10-4 – 6.91 x 10-3g/L) in different samples in alcoholic beverages, presented a maximum deviation of only 2.1%. Assays of recovery of the substrate (99.25%) added in the wine showed that the methodology is viable for this sample type. The standard curve and the analytic curve of this method meet the conditions of precision, sensitivity, simplicity, and low cost, required for a useable analytical method.

Sugars metabolism and ethanol production by different yeast strains from coffee industry wastes hydrolysates

Significant amounts of wastes are generated by the coffee industry, among of which, coffee silverskin (CS) and spent coffee grounds (SCG) are the most abundantly generated during the beans roasting and instant coffee preparation, respectively. This study evaluated the sugars metabolism and production of ethanol by three different yeast strains (Saccharomyces cerevisiae, Pichia stipitis and Kluyveromyces fragilis) when cultivated in sugar rich hydrolysates produced by acid hydrolysis of CS and SCG. S. cerevisiae provided the best ethanol production from SCG hydrolysate (11.7 g/l, 50.2% efficiency). On the other hand, insignificant (<= 1.0 g/l) ethanol production was obtained from CS hydrolysate, for all the evaluated yeast strains, probably due to the low sugars concentration present in this medium (approx. 22 g/l). It was concluded that it is possible to reuse SCG as raw material for ethanol production, which is of great interest for the production of this biofuel, as well as to add value to this agro-industrial waste. CS hydrolysate, in the way that is produced, was not a suitable fermentation medium for ethanol production; however, the hydrolysate concentration for the sugars content increase previous the use as fermentation medium could be an alternative to overcome this problem. (C) 2011 Elsevier Ltd. All rights reserved.

Disulfide Biochemistry in 2-Cys Peroxiredoxin: Requirement of Glu50 and Arg146 for the Reduction of Yeast Tsa1 by Thioredoxin

2-Cys peroxiredoxin (Prx) enzymes are ubiquitously distributed peroxidases that make use of a peroxidatic cysteine (Cys(P)) to decompose hydroperoxides. A disulfide bond is generated as a consequence of the partial unfolding of the alpha-helix that contains Cys(P). Therefore, during its catalytic cycle, 2-Cys Prx alternates between two states, locally unfolded and fully folded. Tsa1 (thiol-specific antioxidant protein 1 from yeast) is by far the most abundant Cys-based peroxidase in Saccharomyces cerevisiae. In this work, we present the crystallographic structure at 2.8 angstrom resolution of Tsa1(C47S) in the decameric form [(alpha(2))(5)] with a DTT molecule bound to the active site, representing one of the few available reports of a 2-Cys Prx (AhpC-Prx1 subfamily) (AhpC, alkyl hydroperoxide reductase subunit C) structure that incorporates a ligand. The analysis of the Tsa1(C47S) structure indicated that G1u50 and Arg146 participate in the stabilization of the Cys(P) alpha-helix. As a consequence, we raised the hypothesis that G1u50 and Arg146 might be relevant to the Cys(P) reactivity. Therefore, Tsa1(E50A) and Tsa1(R146Q) mutants were generated and were still able to decompose hydrogen peroxide, presenting a second-order rate constant in the range of 10(6) M-1 S-1. Remarkably, although Tsa1(E50A) and Tsa1(R146Q) were efficiently reduced by the low-molecular-weight reductant DTT, these mutants displayed only marginal thioredoxin (Trx)-dependent peroxidase activity, indicating that G1u50 and Arg146 are important for the Tsa1-Trx interaction. These results may impact the comprehension of downstream events of signaling pathways that are triggered by the oxidation of critical Cys residues, such as Trx. (C) 2012 Elsevier Ltd. All rights reserved.

Identification of Regions Involved in Substrate Binding and Dimer Stabilization within the Central Domains of Yeast Hsp40 Sis1

Protein folding, refolding and degradation are essential for cellular life and are regulated by protein homeostatic processes such those that involve the molecular chaperone DnaK/Hsp70 and its co-chaperone DnaJ. Hsp70 action is initiated when proteins from the DnaJ family bind an unfolded protein for delivery purposes. In eukaryotes, the DnaJ family can be divided into two main groups, Type I and Type II, represented by yeast cytosolic Ydj1 and Sis1, respectively. Although sharing some unique features both members of the DnaJ family, Ydj1 and Sis1 are structurally and functionally distinct as deemed by previous studies, including the observation that their central domains carry the structural and functional information even in switched chimeras. In this study, we combined several biophysical tools for evaluating the stability of Sis1 and mutants that had the central domains (named Gly/Met rich domain and C-terminal Domain I) deleted or switched to those of Ydj1 to gain insight into the role of these regions in the structure and function of Sis1. The mutants retained some functions similar to full length wild-type Sis1, however they were defective in others. We found that: 1) Sis1 unfolds in at least two steps as follows: folded dimer to partially folded monomer and then to an unfolded monomer. 2) The Gly/Met rich domain had intrinsically disordered characteristics and its deletion had no effect on the conformational stability of the protein. 3) The deletion of the C-terminal Domain I perturbed the stability of the dimer. 4) Exchanging the central domains perturbed the conformational stability of the protein. Altogether, our results suggest the existence of two similar subdomains in the C-terminal domain of DnaJ that could be important for stabilizing each other in order to maintain a folded substrate-binding site as well as the dimeric state of the protein.

CHEMICAL COMPOSITION OF SUGAR CANE SPIRITS FERMENTED BY DIFFERENT Saccharomyces cerevisiae YEAST STRAINS

CHEMICAL COMPOSITION OF SUGAR CANE SPIRITS FERMENTED BY DIFFERENT Saccharomyces cerevisiae YEAST STRAINS. The aim of this study was to evaluate the chemical composition of sugar cane spirits, fermented by different commercial Saccharomyces cerevisiae yeast strains and double distilled by pot still. Sugar cane juices were separately fermented by yeasts CA-11, Y-904, BG-1, PE-2, SA-1 and CAT-1 and distilled by pot still according to the methodology used for whisky production. The alcoholic liquids from first and second distillations were analyzed for concentrations of ethanol, volatile acidity, aldehydes, esters, furfural, higher alcohols and methanol. The sugar cane spirits derived from fermentation by the different yeast strains presented distinct chemical compositions.