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URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11847
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Item Spectroscopic and thermodynamic properties of Debaryomyces hansenii UFV-1 α-galactosidases(International Journal of Biological Macromolecules, 2010-04-01) Rezende, Sebastião T.; Viana, Pollyanna A.; Meza, Andreia N.; Gomide, Felipe T.F.; Nagem, Ronaldo A.P.; Santos, Alexandre M.C.; Santoro, Marcelo M.; Guimarães, Valéria M.Spectroscopic and thermodynamic properties were determined for Debaryomyces hansenii UFV-1 extracellular and intracellular α-galactosidases. α-Galactosidases showed similar secondary structure compositions (α-helix, β-sheet parallel and β-turn). Effects of pH and temperature on the structure of α-galactosidases were investigated using circular dichroism spectroscopy. It was more pronounced at low pH. Microcalorimetry was employed for the determination of thermodynamic parameters. Immediate thermal denaturation reversibility was not observed for α-galactosidases; it occurred as a thermodynamically driven process. Extracellular α-galactosidase, at pH 5.5, showed lower Tm when compared to the intracellular enzyme. The CD and DSC data suggest that D. hansenii α-galactosidases have different behaviors although they possess some similar secondary structures.Item Activity of Debaryomyces hansenii UFV-1 a-galactosidases against a-D-galactopyranoside derivatives(Carbohydrate Research, 2011-04-01) Rezende, Sebastião T. de; Viana, Pollyanna A.; Alves, Arianne de A.; Manfrini, Rozângela M.; Alves, Ricardo J.; Bemquerer, Marcelo P.; Santoro, Marcelo M.; Guimarães, Valéria M.α-d-Galactopyranosides were synthesized and their inhibitory activities toward the Debaryomyces hansenii UFV-1 extracellular and intracellular α-galactosidases were evaluated. Methyl α-d-galactopyranoside was the most potent inhibitor compared to the others tested, with values of 0.82 and 1.12 mmol L−1, for extracellular and intracellular enzymes, respectively. These results indicate that the presence of a hydroxyl group in the C-6 position of α-d-galactopyranoside derivatives is important for the recognition by D. hansenii UFV-1 α-galactosidases.Item Characterization of an exoinulinase produced by Aspergillus terreus CCT 4083 grown on sugar cane bagasse(Journal of Agricultural and Food Chemistry, 2010-02-07) Coitinho, Juliana B.; Guimarães, Valéria M.; Almeida, Maíra N. de; Falkoski, Daniel L.; Queiróz, José H. de; Rezende, Sebastião T. deExoinulinase (β- D -fructan fructohydrolase, EC 3.2.1.80) secreted by Aspergillus terreus CCT4083 was obtained using sugar cane bagasse, an agroindustrial residue, as a carbon source. It was further purified from the supernatant culture in a rapid procedure. The enzyme presented 57 kDa on SDS-PAGE and 56 kDa on gel filtration chromatography. Inulin was hydrolyzed by the purified enzyme, yielding D -fructose as the main product. This enzyme showed maximum activity at pH 4.0 and 60 °C and maintained more than 90 and 75% of its original activity at 40 and 50 °C, respectively, after 3.5 h of preincubation. The K M values for inulin, sucrose, and raffinose were 11, 4.20, and 27.89 mM, respectively, and D -fructose was a competitive inhibitor (K i = 47.55 mM). The activation energies for sucrose, raffinose, and inulin were 10.4, 5.61, and 4.44 kcal/mol, respectively. The characteristics of A. terreus exoinulinase were compared to those of inulinases isolated from other organisms. The exoinulinase traits presented especially good thermostability and the ability to produce pure D -fructose, suggesting its application to the production of high-fructose syrup.Item Optimization of Endoglucanase and Xylanase activities from fusarium verticillioides for simultaneous saccharification and fermentation of sugarcane bagasse(Applied Biochemistry and Biotechnology, 2013-10-30) Almeida, Maíra N. de; Guimarães, Valéria M.; Falkoski, Daniel L.; Paes, Guilherme B. T.; Ribeiro Jr., José Ivo; Visser, Evan M.; Alfenas, Rafael F.; Pereira, Olinto L.; Rezende, Sebastião T. deEnzymatic hydrolysis is an important but expensive step in the production of ethanol from biomass. Thus, the production of efficient enzymatic cocktails is of great interest for this biotechnological application. The production of endoglucanase and xylanase activites from F. verticillioides were optimized in a factorial design (25) followed by a CCDR design. Endoglucanase and xylanase activities increased from 2.8 to 8.0 U/mL and from 13.4 to 114 U/mL, respectively. The optimal pH and temperature were determined for endoglucanase (5.6, 80 °C), cellobiase (5.6, 60 °C), FPase (6.0, 55 °C) and xylanase (7.0, 50 °C). The optimized crude extract was applied in saccharification and fermentation of sugarcane bagasse from which 9.7 g/L of ethanol was produced at an ethanol/biomass yield of 0.19.Item Direct ethanol production from glucose, xylose and sugarcane bagasse by the corn endophytic fungi Fusarium verticillioides and Acremonium zeae(Journal of Biotechnology, 2013-07-31) Almeida, Maíra N. de; Guimarães, Valéria M.; Falkoski, Daniel L.; Visser, Evan M.; Siqueira, Germano A.; Milagres, Adriane M.F.; Rezende, Sebastião T. deProduction of ethanol with two corn endophytic fungi, Fusarium verticillioides and Acremonium zeae, was studied. The yield of ethanol from glucose, xylose and a mixture of both sugars were 0.47, 0.46 and 0.50 g/g ethanol/sugar for F. verticillioides and 0.37, 0.39 and 0.48 g/g ethanol/sugar for A. zeae. Both fungi were able to co-ferment glucose and xylose. Ethanol production from 40 g/L of pre-treated sugarcane bagasse was 4.6 and 3.9 g/L for F. verticillioides and A. zeae, respectively, yielding 0.31 g/g of ethanol per consumed sugar. Both fungi studied were capable of co-fermenting glucose and xylose at high yields. Moreover, they were able to produce ethanol directly from lignocellulosic biomass, demonstrating to be suitable microorganisms for consolidated bioprocessing.Item Characteristics of free endoglucanase and glycosidases multienzyme complex from Fusarium verticillioides(Bioresource Technology, 2013-06-08) Almeida, Maíra N.de; Falkoski, Daniel L.; Guimarães, Valéria M.; Ramos, Humberto Josué de O.; Visser, Evan M.; Maitan-Alfenas, Gabriela P.; Rezende, Sebastião T. deA novel multienzyme complex, E1 C , and a free endoglucanase, E2 (GH5), from Fusarium verticillioides were purified. The E1 C contained two endoglucanases (GH6 and GH10), one cellobiohydrolase (GH7) and one xylanase (GH10). Maximum activity was observed at 80 °C for both enzymes and they were thermostable at 50 and 60 °C. The activation energies for E1 C and E2 were 21.3 and 27.5 kJ/mol, respectively. The K M for E1 C was 10.25 g/L while for E2 was 6.58 g/L. Both E1 C and E2 were activated by Mn 2+ and CoCl 2 while they were inhibited by SDS, CuSO 4 , FeCl 3 , AgNO 4 , ZnSO 4 and HgCl 2 . E1 C and E2 presented endo-b-1,3–1,4-glucanase activity. E1 C presented crescent activity towards cellopentaose, cellotetraose and cellotriose. E2 hydrolyzed the substrates cellopentaose, cellotetraose and cellotriose with the same efficiency. E1 C showed a higher stability and a better hydrolysis performance than E2, suggesting advantages resulting from the physical interaction between proteins.Item Production and Characterization of β-Glucanase Secreted by the Yeast Kluyveromyces marxianus(Applied Biochemistry and Biotechnology, 2014-01-04) Lopes, Mariana R.; Souza, Carlos J. A. de; Rodrigues, Marina Q. R. B.; Costa, Daniela A.; Santos, Ancély F. dos; Oliveira, Leandro L. de; Ramos, Humberto J. O.; Guimarães, Valéria M.; Silveira, Wendel B.; Passos, Flávia M. L.; Fietto, Luciano G.An extracellular β-glucanase secreted by Kluyveromyces marxianus was identified for the first time. The optimal conditions for the production of this enzyme were evaluated by response surface methodology. The optimal conditions to produce β-glucanase were a glucose concentration of 4 % (w/v), a pH of 5.5, and an incubation temperature of 35 °C. Response surface methodology was also used to determine the pH and temperature required for the optimal enzymatic activity. The highest enzyme activity was obtained at a pH of 5.5 and a temperature of 55 °C. Furthermore, the enzyme was partially purified and sequenced, and its specificity for different substrates was evaluated. The results suggest that the enzyme is an endo-β-1,3(4)-glucanase. After optimizing the conditions for β-glucanase production, the culture supernatant was found to be effective in digesting the cell wall of the yeast Saccharomyces cerevisiae, showing the great potential of β-glucanase in the biotechnological production of soluble β-glucan.Item Hydrolysis of soybean isoflavones by Debaryomyces hansenii UFV-1 immobilised cells and free β-glucosidase(Food Chemistry, 2014-03-01) Maitan-Alfenas, Gabriela P.; Lage, Lorena G. de A.; Almeida, Maíra N. de; Visser, Evan M.; Rezende, Sebastião T. de; Guimarães, Valéria M.An intracellular β-glucosidase from Debaryomyces hansenii UFV-1 was produced in an YP medium with cellobiose as the carbon source. This enzyme was purified, characterised and presented a Mr of 65.15 kDa. Yeast cells containing the intracellular β-glucosidase were immobilised in calcium alginate. The free β-glucosidase and immobilised cells containing the enzyme presented optima values of pH and temperature of 6.0 and 45 °C and 5.5 and 50 °C, respectively. The free enzyme maintained 62% and 47% of its original activity after 90 days at 4 °C and after 15 days at room temperature, respectively. The immobilisation process resulted in higher enzyme thermostability at 45 and 50 °C. Soy molasses treatment with the free enzyme and the immobilised cells containing β-glucosidase, for 2 h at 40 °C, promoted efficient hydrolysis of isoflavone glicosides to their aglycon forms. The results suggest that this enzyme could be used in the food industry, in the free or immobilised forms, for a safe and efficient process to hydrolyse isoflavone glycosides in soy molasses.