7 research outputs found
NADH-linked aldose reductase: The key to anaerobic alcoholic fermentation of xylose by yeasts
No full textThe kinetics and enzymology of o-xylose utilization were studied in aerobic and anaerobic batch cultures of the facultatively fermentative yeasts Candida utilis, Pachysolen tannophilus, and Pichia stipitis. These yeasts did not produce ethanol under aerobic conditions. When shifted to anaerobiosis cultures of C. utilis did not show fermentation of xylose; in Pa. tannophilus a very low rate of ethanol formation was apparent, whereas with Pi. stipitis rapid fermentation of xylose occurred. The different behaviour of these yeasts ist most probably explained by differences in the nature of the initial steps of xylose metabolism: in C. utilis xylose is metabolized via an NADPH-dependent xylose reductase and an NAD+-linked xylitol dehydrogenase. As a consequence, conversion of xylose to ethanol by C. utilis leads to an overproduction of NADH which blocks metabolic activity in the absence of oxygen. In Pa. tannophilus and Pi. stipitis, however, apart from an NADPH-linked xylose reductase also an NADH-linked xylose reductase was present. Apparently xylose metabolism via the NADH-dependent reductase circumvents the imbalance of the NAD+/NADH redox system, thus allowing fermentation of xylose to ethanol under anaerobic conditions. The finding that the rate of xylose fermentation in Pa. tannophilus and Pi. stipitis corresponds with the activity of the NADH-linked xylose reductase activity is in line with this hypothesis. Furthermore, a comparative study with various xylose-assimilating yeasts showed that significant alcoholic fermentation of xylose only occurred in those organisms which possessed NADH-linked aldose reductaseApplied Science
Method for treating vegetable material with acid as well as products obtained with this method
No full textThe present invention relates to a method for treating carbohydrate- containing vegetable material with acid, comprising the steps of: (a) providing a mixture of a carbohydrate-containing vegetable material, an organic acid and, if necessary, water, (b) heating the mixture obtained in step (a) to a temperature of at least 120 °C for some time so as to obtain a mixture comprising an acid-treated insoluble vegetable material, water, a carbohydrate-containing vegetable material that has been rendered soluble and possibly an organic acid, (c) repeating step (b) at least once, with steps (d) and (e) being carried out prior to step (b): (d) separating the acid-treated insoluble vegetable material from the mixture obtained in step (b) so as to obtain a liquid fraction which comprises carbohydrate-containing vegetable material that has been rendered soluble, (e) adding additional carbohydrate-containing vegetable material and possibly additional organic acid to the liquid fraction obtained in step (d), wherein the mixture that is used upon repeating step (b) is the mixture that is obtained in step (e)
Method for treating vegetable material with acid as well as products obtained with this method
No full textThe present invention relates to a method for treating carbohydrate- containing vegetable material with acid, comprising the steps of: (a) providing a mixture of a carbohydrate-containing vegetable material, an organic acid and, if necessary, water, (b) heating the mixture obtained in step (a) to a temperature of at least 120 °C for some time so as to obtain a mixture comprising an acid-treated insoluble vegetable material, water, a carbohydrate-containing vegetable material that has been rendered soluble and possibly an organic acid, (c) repeating step (b) at least once, with steps (d) and (e) being carried out prior to step (b): (d) separating the acid-treated insoluble vegetable material from the mixture obtained in step (b) so as to obtain a liquid fraction which comprises carbohydrate-containing vegetable material that has been rendered soluble, (e) adding additional carbohydrate-containing vegetable material and possibly additional organic acid to the liquid fraction obtained in step (d), wherein the mixture that is used upon repeating step (b) is the mixture that is obtained in step (e)
Analysis of Pollen and Nectar of Arbutus unedo as a Food Source for Bombus terrestris (Hymenoptera : Apidae)
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Atividade moduladora do extrato hidroalcoólico de própolis catarinense na formação de vasos sanguíneos
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas. Programa de Pós-Graduação em Biologia Celular e do Desenvolvimento, Florianópolis, 2013.Inúmeros estudos relacionados à formação de vasos sanguíneos abordam ocorrência de atividade moduladora exercida por produtos naturais no microambiente das células endoteliais. A própolis vem sendo investigada como uma candidata à modulação angiogênica. Entre seus constituintes químicos, encontram-se ácidos fenólicos, ésteres, flavonóides, terpenos, beta-esteróides, aldeídos aromáticos, sesquiterpenos e estilbeno-terpenos, entre outros grupos, sendo que sua composição pode variar de acordo com a fonte botânica do exsudato coletado, bem como das condições ambientais. O extrato hidroalcoólico de própolis coletado no outono/2010 no planalto serrano (município de São Joaquim) teve a sua ação investigada na viabilidade celular, na capacidade de proliferação, na função migratória e na tubulogênese de células endoteliais de veia umbilical humana. Esse extrato apresentou teores elevados de ácidos fenólicos (ácido gálico, ácido protocatecuico, ácido clorogênico e seus ésteres como o ácido isoclorogênico A e ácido isoclorogênico C) e do flavonoide quercetina. O extrato (100 - 200 µg/ml) produziu citotoxicidade e diminuição dos mecanismos de proliferação, migração e tubulogênese. Ele também foi capaz de reverter o efeito proliferativo do fator de crescimento vascular endotelial nas células endoteliais. A atividade da metaloproteinase-9 não foi alterada com 200 µg/ml do extrato. Porém, esta mesma concentração inibiu a atividade proliferativa da proteína quinase C e promoveu um efeito aditivo na inibição do efeito proliferativo da enzima cicloxigenase 1 e 2. Além disso, a administração do composto puro quercetina isoladamente (40 µM) ou em associação com o extrato (200 µg/ml), inibiu a proliferação celular. No ensaio de morte celular, evidenciou-se uma tendência à ação pró-necrótica do extrato. Quando o extrato de própolis foi administrado, in vivo, em membranas extra-embrionárias de Gallus domesticus, observou-se significativa inibição dos processos de vasculogênese e angiogênese. Os resultados desses ensaios in vitro e in vivo evidenciam o efeito modulador do extrato hidroalcoólico de própolis outonal catarinense na formação de vasos sanguíneos indicando aplicação em condições patológicas caracterizadas e sustentadas por uma angiogênese excessiva.Abstract : A number of studies regarding the formation of blood vessels approach the occurrence of modulatory activity exerted by natural products in the microenvironment of endothelial cells. Propolis has been investigated as a candidate for angiogenic modulation. Among the chemical constituents of that complex matrix are phenolic acids, esters, flavonoids, terpenes, beta-steroids, aromatic aldehydes, terpenes, sesquiterpenes, stilbenes and others groups, and its composition may vary according to the botanical source of exudates collected as well as, the environmental conditions. Hydroalcoholic propolis extract collected at autumn/2010 in Santa Catarina State (São Joaquim county) was investigated regarding its action on the cell viability, proliferation and migration, and also on the tubulogenesis of human umbilical vein endothelial cells. This extract has showed a high content of phenolic acids (gallic acid, protocatechuic acid, chlorogenic acid and its ester derivates isochlorogenic acid A and isochlorogenic acid C) and the flavonoid quercetin. Propolis extract displayed cytotoxic activity (100 - 200 µg/ml) and decreased the mechanisms of proliferation, cell migration, and vascular tubulogenesis. The propolis extract was also able in to reverse the proliferative effects of vascular endothelial growth factor on endothelial cells. Activity of metalloproteinase-9 was not influenced by 200 µg/ml extract. However, this treatment inhibited the proliferative activity of protein kinase C and promoted an additive effect in the inhibition of proliferative effect carried by cyclooxygenase 1 and 2. Moreover, the pure compound quercetin when administered alone (40 µM) or in association with the extract inhibited the cell proliferation. Cell death assay showed a tendency a pro-necrotic action by the extract under study. When administered in vivo in extra-embryonic membranes of Gallus domesticus, the propolis extract promoted a significant inhibition of the vasculogenesis and angiogenesis. Taken together, the in vitro and in vivo findings evidence the modulatory effects of propolis extract studied on the blood vessels formation, and suggest application in morbidities characterized and sustained by excessive angiogenesis
Análise de supressores da fermentação de xilose em saccharomyces cerevisiae
No full textO Brasil se destaca como o segundo maior produtor mundial de bioetanol, sendo detentor do processo de produção mais eficaz e rentável, baseado exclusivamente na utilização da cana-de-açúcar. Porém, apenas um terço de sua biomassa é utilizado para produção de bioetanol. O restante da biomassa (bagaço, folhas e palha) é queimado para a produção de vapor e eletricidade. Estes materiais são compostos majoritariamente de fibras de lignocelulose que são extremamente ricas em açúcares, apresentando grande potencial para produção adicional de bioetanol. A levedura Saccharomyces cerevisiae é o microrganismo mais amplamente utilizado na produção industrial de etanol, sendo capaz de fermentar eficientemente açúcares como a sacarose (principal açúcar presente na cana-de-açúcar) e hexoses. No entanto, essa levedura, em sua condição natural, é incapaz de fermentar pentoses como a xilose, o segundo açúcar mais abundante na biomassa da cana-de-açúcar. O sucesso das tecnologias de produção de biocombustíveis de segunda geração depende, portanto, de leveduras capazes de fermentar tanto as hexoses quanto as pentoses presentes na biomassa lignocelulósica. Recentemente, alguns estudos têm reportado que os genes BUD21 e PHO13 funcionam como possíveis supressores da metabolização de xilose em S. cerevisiae. O objetivo do presente estudo foi avaliar o efeito da deleção dos referidos genes em linhagens industriais diploides utilizadas para a produção de etanol combustível no Brasil. Para tanto, utilizou-se técnicas de biologia molecular baseadas em recombinação homóloga para deletar do genoma de S. cerevisiae o(s) gene(s) BUD21 e PHO13. Nossos resultados mostraram que linhagens de laboratório com deleção do gene BUD21 (bud21?) foram incapazes de utilizar xilose como fonte de carbono, sugerindo que este gene não é um supressor da metabolização de xilose nas leveduras analisadas. Numa segunda abordagem, o gene PHO13 foi deletado numa levedura industrial diploide recombinante que sobre-expressa os genes necessários à metabolização de xilose (genes XYL1, XYL2 e XKS1). A linhagem industrial pho13? / pho13? foi capaz de crescer em meios sólidos contendo altas concentrações de xilose, e em cultivos em frascos agitados, a deleção do gene PHO13 melhorou significativamente oconsumo da xilose, bem como a produção de biomassa e de etanol pela linhagem industrial recombinante. No entanto, ensaios de fermentação em batelada simples em condições microaeróbias revelaram que a deleção do PHO13 não melhora a fermentação da xilose. Resultados semelhantes foram encontrados nos ensaios de co-fermentações de xilose/glicose e xilose/sacarose.Abstract : Brazil stands as the second largest world producer of bioethanol, having the most efficient and profitable production process, based exclusively on the use of sugarcane. However, only a third of its biomass is used for bioethanol production. The remaining biomass (bagasse, leaves and straw) is burned to produce steam and electricity. These materials are composed mostly of lignocellulosic fibers that are extremely rich in sugars, with great potential for further production of bioethanol. The yeast Saccharomyces cerevisiae is the microorganism most widely used in the industrial production of ethanol, been able to efficiently ferment sugars such as sucrose (the principal sugar present sugarcane) and hexoses. However, this yeast, in its natural condition, is unable to ferment pentoses such as xylose, the second most abundant sugar in the sugarcane biomass. The success of the technologies of second generation biofuels production, therefore, depends on yeast capable of fermenting hexoses as well as pentoses present in the lignocellulosic biomass. Recently some studies have reported that the BUD21 and PHO13 genes function as potential suppressors of xylose metabolism in S. cerevisiae. The aim of this study was to evaluate the effect of the deletion of these genes in diploid industrial strains used for the production of fuel ethanol in Brazil. For this, we used molecular biology techniques based on homologous recombination to delete the BUD21 and PHO13 gene(s) from the S. cerevisiae genome. Our results showed that laboratory strains deleted in the BUD21 gene (bud21?) were unable to use xylose as a carbon source, suggesting that this gene is not a suppressor of xylose metabolism in the analyzed yeasts. In a second approach, the PHO13 gene was deleted in a recombinant diploid industrial yeast overexpressing the genes required for xylose metabolism (XYL1, XYL2 and XKS1 genes). The industrial pho13? / pho13? strain was able to grow on solid media containing high concentrations of xylose, and in flasks cultivations, the deletion of the PHO13 gene significantly improved xylose consumption, as well as production of biomass and ethanol by the industrial recombinant strain. However, assays in simple batch fermentation under conditions of limited oxygen revealed that deletion of PHO13 no improvement ofxylose fermentation. Similar results were found in assays of co-fermentation of xylose / glucose and xylose / sucrose
Efecto del pretratamiento con ultrasonido en la cinética de secado convencional de banano (musa paradisiaca)
No full textThe use of ultrasound in food processing has increased in the last decade due to the reduction in times, temperatures, microbial and enzymatic inactivation, extraction of components of great interest to different industries; without altering or modifying its nutritional or organoleptic value during the transformation processes of raw materials into products with added value. Considering itself, a green technology by not causing a negative impact on the environment. In this work, the effect of US pretreatment (40KHz/130W/30°C /10, 20 and 30 min) on convective drying at 60°C / 2m / s of banana (musa paradisiaca) was evaluated. A diffusion model was used to describe the drying kinetics and to quantify the influence of the US on the effective diffusivity of water. Observing that the US significantly increased (p> 0.05) the drying speed in all the samples treated with an average reduction of 31% in the drying time with respect to the control treatment; reaching a weight loss of 77% with respect to the initial weight (3.8 to 0.9 g.). The exponential model is the most adequate to predict the experimental curves of banana drying and showed that the application of US increased both the effective diffusivity and the mass transfer coefficient, as corroborated by the values of the explained variance of 98.5 a 99.3%.El uso del ultrasonido en el procesamiento de alimentos se ha incrementado en la última década debido a la reducción en tiempos, temperaturas, inactivación microbiana y enzimática, extracción de componentes de gran interés para diferentes industrias; sin alterar o modificar su valor nutricional u organoléptico durante los procesos de trasformación de las materias primas en productos con valor agregado. Considerandose, una tecnología verde al no causar impacto negativo al medio ambiente. En este trabajo se evaluó el efecto del pretratamiento con US (40 KHz/130W/30°C /10, 20 y 30 min) en el secado convectivo a 60°C/2m/s del banano (musa paradisiaca). Se utilizó un modelo difusional para describir las cinéticas de secado y cuantificar la influencia del US en la difusividad efectiva de agua. Observando que el US incrementó significativamente (p>0.05) la velocidad de secado en todas las muestras tratadas con una reducción promedio del 31% en el tiempo de secado con respecto al tratamiento control; alcanzando una pérdida de peso del 77% respecto del peso inicial (3.8 a 0.9 g.). El modelo exponencial es el más adecuado para predecir las curvas experimentales de secado del banano y mostró que la aplicación de US aumentó tanto la difusividad efectiva y el coeficiente de transferencia de masa, como corroboran los valores del porcentaje de varianza explicada de 98.5 a 99.3%
