Navegando por Autor "Passos, Flávia Maria Lopes"
Agora exibindo 1 - 10 de 10
- Resultados por Página
- Opções de Ordenação
Item Applying functional metagenomics to search for novel lignocellulosic enzymes in a microbial consortium derived from a thermophilic composting phase of sugarcane bagasse and cow manure(Antonie van Leeuwenhoek, 2016-06-27) Colombo, Lívia Tavares; Oliveira, Marcelo Nagem Valério de; Carneiro, Deisy Guimarães; Souza, Robson Assis de; Alvim, Mariana Caroline Tocantins; Santos, Josenilda Carlos dos; Silva, Cynthia Canêdo da; Vidigal, Pedro Marcus Pereira; Silveira, Wendel Batista da; Passos, Flávia Maria LopesEnvironments where lignocellulosic biomass is naturally decomposed are sources for discovery of new hydrolytic enzymes that can reduce the high cost of enzymatic cocktails for second-generation ethanol production. Metagenomic analysis was applied to discover genes coding carbohydrate-depleting enzymes from a microbial laboratory subculture using a mix of sugarcane bagasse and cow manure in the thermophilic composting phase. From a fosmid library, 182 clones had the ability to hydrolyse carbohydrate. Sequencing of 30 fosmids resulted in 12 contigs encoding 34 putative carbohydrate-active enzymes belonging to 17 glycosyl hydrolase (GH) families. One third of the putative proteins belong to the GH3 family, which includes β-glucosidase enzymes known to be important in the cellulose-deconstruction process but present with low activity in commercial enzyme preparations. Phylogenetic analysis of the amino acid sequences of seven selected proteins, including three β-glucosidases, showed low relatedness with protein sequences deposited in databases. These findings highlight microbial consortia obtained from a mixture of decomposing biomass residues, such as sugar cane bagasse and cow manure, as a rich resource of novel enzymes potentially useful in biotechnology for saccharification of lignocellulosic substrate.Item Characterization of a thermotolerant laccase produced by Streptomyces sp. SB086(Annals of Microbiology, 2013-12-28) Fernandes, Tatiana Alves Rigamonte; Silveira, Wendel Batista da; Passos, Flávia Maria Lopes; Zucchi, Tiago DominguesLaccases have become desirable enzymes for application in many industrial processes. Nowadays, most of these enzymes are obtained from fungi. Among prospective studies for bacterial laccase genes, some have included actinomycetes, but only a few studies have characterized the enzyme produced. Thus, we have isolated a laccase-producing actinomycete from forest soil under restoration process and further aimed to characterize its produced enzyme. The isolate SB086 was assigned to the Streptomyces genus by a combination of phenotypical, chemical and phylogenetic properties. Our data indicate that the bacterium produces a thermotolerant laccase. The maximum activity was obtained in the pH range 4.0–5.0 and at 50 °C in reaction mixture containing 5 mM CuSO4; thermal stability was noted at 60 °C and 70 °C—a well-desired characteristic for industry. The active enzyme presented a high molecular mass (over 100 kDa) and was less sensitive to inhibition by metal ions than generally described for bacterial laccases. Our findings support in silico data of bacterial laccase secretion, and reinforce the view that actinomycetes may be a rich source of laccase for industrial application.Item Chemical structure, antiproliferative and antioxidant activities of a cell wall α-d-mannan from yeast Kluyveromyces marxianus(Carbohydrate Polymers, 2017-02-10) Galinari, Éder; Sabry, Diego Araújo; Sassaki, Guilherme Lanzi; Macedo, Gorete Ribeiro; Passos, Flávia Maria Lopes; Mantovani, Hilário Cuquetto; Rocha, Hugo Alexandre OliveiraCell wall polysaccharides from filamentous fungi and yeasts have been reported as antioxidant and antiproliferative polymers. Thus, we evaluated these activities from cell wall polysaccharides from Kluyveromyces marxianus CCT7735. By using a centrifugal filter, a 203 kDa α-d-mannan (KMM-5) was obtained. KMM-5 exhibited no effect on HeLa cells and a weak antiproliferative activity against Hep-G2 cells. In addition, at higher concentrations, it presented a cytotoxicity to the normal cell line, 3T3. However, KMM-5 showed copper- and iron-chelating abilities, the latter of which presented improved activity. By using 2D-NMR COSY, HSQC edited and HMBC experiments, a structure arrangement was proposed. The main chain was formed by 6)-α-d-Manp-(1 → 6) units substituted at the 2-O-position by non-reducing terminals α-d-Manp-(1 → 2) and by a branched tetrasaccharide. The latter was formed by an internal 2)-α-d-Manp-(1 → 2) unit with linked to it a 2,3)-α-d-Manp-(1 → 2) unit substituted at the 2-O-position by a non-reducing terminal α-d-Manp-(1 → 2), and at the 3-O-position by a non-reducing terminal α-d-Manp-(1 → 3). In conclusion, we considered K. marxianus CCT7735 a source of natural and renewable polysaccharides with pharmacological properties.Item Debaryomyces hansenii UFV-1 intracellular α-Galactosidase characterization and comparative studies with the extracellular enzyme(Journal of Agricultural and Food Chemistry, 2009-02-18) Rezende, Sebastião T. de; Viana, Pollyanna A.; Passos, Flávia Maria Lopes; Oliveira, Jamil S.; Teixeira, Kádima N.; Santos, Alexandre M. C.; Bemquerer, Marcelo P.; Rosa, José C.; Santoro, Marcelo M.; Guimarães, Valéria M.Debaryomyces hansenii cells cultivated on galactose produced extracellular and intracellular α-galactosidases, which showed 54.5 and 54.8 kDa molecular mass (MALDI-TOF), 60 and 61 kDa (SDS−PAGE) and 5.15 and 4.15 pI values, respectively. The extracellular and intracellular deglycosylated forms presented 36 and 40 kDa molecular mass, with 40 and 34% carbohydrate content, respectively. The N-terminal sequences of the α-galactosidases were identical. Intracellular α-galactosidase showed smaller thermostability when compared to the extracellular enzyme. D. hansenii UFV-1 extracellular α-galactosidase presented higher kcat than the intracellular enzyme (7.16 vs 3.29 s^−1, respectively) for the p-nitrophenyl-α-d-galactopyranoside substrate. The Km for hydrolysis of pNPαGal, melibiose, stachyose, and raffinose were 0.32, 2.12, 10.8, and 32.8 mM, respectively. The intracellular enzyme was acompetitively inhibited by galactose (Ki = 0.70 mM), and it was inactivated by Cu(II) and Ag(I). Enzyme incubation with soy milk for 6 h at 55 °C reduced stachyose and raffinose amounts by 100 and 73%, respectively.Item Kinetics of growth and ethanol formation from a mix of glucose/xylose substrate by Kluyveromyces marxianus UFV-3(Antonie van Leeuwenhoek, 2012-09-11) Passos, Flávia Maria Lopes; Santos, Valdilene Canazart dos; Bragança, Caio Roberto Soares; Passos, Frederico José VieiraThe fermentation of both glucose and xylose is important to maximize ethanol yield from renewable biomass feedstocks. In this article, we analyze growth, sugar consumption, and ethanol formation by the yeast Kluyveromyces marxianus UFV-3 using various glucose and xylose concentrations and also under conditions of reduced respiratory activity. In almost all the conditions analyzed, glucose repressed xylose assimilation and xylose consumption began after glucose had been exhausted. A remarkable difference was observed when mixtures of 5 g L^−1 glucose/20 g L^−1 xylose and 20 g L^−1 glucose/20 g L^−1 xylose were used. In the former, the xylose consumption began immediately after the glucose depletion. Indeed, there was no striking diauxic phase, as observed in the latter condition, in which there was an interval of 30 h between glucose depletion and the beginning of xylose consumption. Ethanol production was always higher in a mixture of glucose and xylose than in glucose alone. The highest ethanol concentration (8.65 g L^−1) and cell mass concentration (4.42 g L^−1) were achieved after 8 and 74 h, respectively, in a mixture of 20 g L^−1 glucose/20 g L^−1 xylose. When inhibitors of respiration were added to the medium, glucose repression of xylose consumption was alleviated completely and K. marxianus was able to consume xylose and glucose simultaneously.Item Optimizing ethanol production by thermotolerant Kluyveromyces marxianus CCT 7735 in a mixture of sugarcane bagasse and ricotta wh(Food Science and Biotechnology, 2015-05-01) Ferreira, Priscila Gonçalves; Silveira, Fernando Augusto da; Santos, Raquel Cristina Vieira dos; Genier, Hugo Leonardo André; Diniz, Raphael Hermano Santos; Ribeiro Jr., José Ivo; Fietto, Luciano Gomes; Passos, Flávia Maria Lopes; Silveira, Wendel Batista daThe simultaneous saccharification and fermentation (SSF) process is a promising strategy to obtain ethanol from cellulosic biomass. In this study, sugarcane bagasse was supplemented with ricotta whey to increase the sugar, vitamin, and trace metal concentrations in the fermentation medium. The optimum conditions for SSF ethanol production from a mixture of sugarcane bagasse and ricotta whey produced by Kluyveromyces marxianus CCT 7735 were evaluated considering five factors: cellulase concentration, cellulosic biomass concentration, pH, temperature, and agitation. The highest ethanol yield was 49.65 g/L with a cellulosic biomass of 80 g/L, pH value of 5.05, agitation at 65 rpm and temperature of 39.2°C. The results demonstrated that a mixture of the cellulosic residue of sugarcane bagasse and ricotta whey is promising for ethanol production because the ethanol yield in the mixture was higher than that in single substrate of sugarcane bagasse.Item Optimizing ethanol production by thermotolerant Kluyveromyces marxianus CCT 7735 in a mixture of sugarcane bagasse and ricotta whey(Food Science and Biotechnology, 2015-08) Ferreira, Priscila Gonçalves; Silveira, Fernando Augusto da; Santos, Raquel Cristina Vieira dos; Genier, Hugo Leonardo André; Diniz, Raphael Hermano Santos; Ribeiro Jr., José Ivo; Fietto, Luciano Gomes; Passos, Flávia Maria LopesThe simultaneous saccharification and fermentation (SSF) process is a promising strategy to obtain ethanol from cellulosic biomass. In this study, sugarcane bagasse was supplemented with ricotta whey to increase the sugar, vitamin, and trace metal concentrations in the fermentation medium. The optimum conditions for SSF ethanol production from a mixture of sugarcane bagasse and ricotta whey produced by Kluyveromyces marxianus CCT 7735 were evaluated considering five factors: cellulase concentration, cellulosic biomass concentration, pH, temperature, and agitation. The highest ethanol yield was 49.65 g/L with a cellulosic biomass of 80 g/L, pH value of 5.05, agitation at 65 rpm and temperature of 39.2°C. The results demonstrated that a mixture of the cellulosic residue of sugarcane bagasse and ricotta whey is promising for ethanol production because the ethanol yield in the mixture was higher than that in single substrate of sugarcane bagasse.Item Production of pectin lyase by Penicillium griseoroseum in bioreactors in the absence of inducer(Brazilian Journal of Microbiology, 2001-04) Passos, Flávia Maria Lopes; Passos, Frederico José Vieira; Silva, Daison Olzany; Piccoli-Valle, Roberta HilsdorfPenicillium griseoroseum was grown in bioreactors on mineral medium supplemented with yeast extract and sucrose. The influence of inoculum and carbon source concentrations, aeration and pH on pectin lyase (PL) production, as well as the capacity of P. griseoroseum to produce PL when grown on sugar cane syrup as carbon source were evaluated. Inoculum concentration did not influence PL production. Production was higher in non-aerated than in aerated medium. The best results were obtained using 60 mM sucrose at pH 6.3-7.2. Production using cane syrup 25% (v/v), without yeast extract supplement, was equal to that obtained under the conditions cited above.Item Signals of aging associated with lower growth rates in Kluyveromyces lactis cultures under nitrogen limitation(Canadian Journal of Microbiology, 2014) Corrêa, Lygia Fátima da Mata; Passos, Frederico José Vieira; Viloria, Marlene Isabel Vargas; Martins Filho, Olindo Assis; Carvalho, Andréa Teixeira de; Passos, Flávia Maria LopesThe effects of aging on the specific growth rate of Kluyveromyces lactis cultures, as a function of (NH4)2SO4 concentration, were evaluated. The growth kinetic parameters maximum specific growth rate and saturation constant for (NH4)2SO4 were calculated to be 0.44 h−1 and 0.15 mmol·L−1, respectively. Batch cultures were allowed to age for 16 days without influence of cell density or starvation. The specific growth rates of these cultures were determined each day and decreased as the population aged at different nitrogen concentrations. Aging signals (N-acetylglucosamine content of the cell wall, cell dimensions, and apoptosis markers) were measured. Apoptosis markers were detected after 5 days at limiting (NH4)2SO4 concentrations (0.57, 3.80, and 7.60 mmol·L−1) but only after 8 days at a nonlimiting (NH4)2SO4 concentration (38.0 mmol·L−1). Similarly, continuous cultures of K. lactis performed under nitrogen limitation and, at lower dilution rates, accumulated cells exhibiting aging signals. The results demonstrate that aging affects growth rate and raise the question of whether nitrogen limitation accelerates aging. Because aging is correlated with growth rate, and each dilution rate of the continuous cultures tends to select and accumulate cells with a respective age, cultures growing at lower growth rates can be useful to investigate yeast physiological responses, including aging.Item α-Galactosidases production by Debaryomyces hansenii UFV-1(Food Science and Biotechnology, 2011-06-30) Viana, Pollyanna Amaral; Rezende, Sebastião Tavares de; Passos, Flávia Maria Lopes; Machado, Solimar Gonçalves; Maitan, Gabriela Picollo; Coelho, Vinicio Tadeu da Silva; Guimarães, Valéria MontezeExtracellular and intracellular α-galactosidases were produced by yeast Debaryomyces hansenii UFV-1 grown on different media with several carbon sources. D. hansenii grown in YP-medium (1% yeast extract and 2% peptone) presented maximum cell mass (8.45 mg/mL) after 36 h of cultivation, with lactose as carbon source, followed by sucrose, glucose, raffinose, and galactose. Higher extracellular and intracellular α-galactosidases activities were observed at 48 h of D. hansenii cultivation in YPmedium containing galactose (0.97 and 5.27 U/mL) and lactose (1.28 and 4.88 U/mL), supporting the evidence for the model of induction for the yeast GAL/MEL regulon, such as described in Sacharomyces cereviseae.