Evaluation of operational parameters on the precipitation of endoglucanase and xylanase produced by solid state fermentation of Aspergillus niger

In order to develop cost effective processes for converting biomass into biofuels, it is essential to improve enzyme production yields, stability and specific activity. In this context, the aim of this work was to evaluate the concentration of two enzymes involved in the hydrolysis of biomass, endoglucanase and xylanase, through precipitation. Statistical experimental design was used to evaluate the influence of precipitant agent concentration (ammonium sulfate and ethanol), aging time, and temperature on enzyme activity recovery. Precipitant agent concentration and aging time showed a statistically significant effect at the 95% confidence level, on both enzyme activity recoveries. The recovery of endoglucanase with ammonium sulfate and ethanol reached values up to 65 and 61%, respectively. For xylanase, the recovery rates were lower, 27 and 25% with ammonium sulfate and ethanol, respectively. The results obtained allowed the selection of the variables relevant to improving enzyme activity recovery within operational conditions suitable for industrial applications.1726Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Análisis Químico del Cacao Criollo Porcelana (Theobroma cacao L.) en el Sur del Lago de Maracaibo Chemical analysis of Criollo Porcelana Cocoa (Theobroma cocoa L.) in the South of Maracaibo Lake

Resumen El estudio de algunos compuestos químicos, tiene gran relevancia en la calidad y desarrollo aromático del cacao, ya que en función del tratamiento al cual sean sometidas las almendras, dependerá el contenido de estos. El presente trabajo tuvo como objetivo evaluar la evolución de algunos compuestos quí-micos en función de la fermentación, tomando en cuenta los siguientes factores: tipo de fermentador (TF), frecuencia de remoción (FR), aguante de la mazorca (AM) y el tiempo de fermentación (TPF). La metodología consistió en un arreglo factorial 2 3 x 5 donde se estudiaron tres factores (TF, FR y AM), a dos niveles y el tiempo de fermentación a cinco. Las variables estudiadas fueron: pH, acidez, taninos, azúcares reductores y totales. Los resultados reflejan para el cotiledón y pulpa + testa mayores valores de pH y taninos en el fermentador rectangular y de acidez, azúcares reductores y totales en el cuadrado. La frecuencia de remoción cada 24 horas, mostró mayor pH, azúcares y taninos y menor acidez en el cotiledón y menores valores en la pulpa + testa y un aumento en los azú-cares y taninos en este. El aguante determinó un incremento del pH para cinco días y un descenso de la acidez y azúcares. En la pulpa + testa se observó la misma tendencia. Para el tiempo de fermentación hubo variación de todas las variables durante el proceso para ambas fracciones, donde el contenido de ellas disminuyo durante fermentación en su gran mayoría. Estos resultados tienen relación con la calidad final del cacao. Abstract This study has as purpose the evaluation of the biochemical parameters that allow to establish the fermentation conditions for producing the best quality chocolate for the "Criollo Porcelana" cacao, by evaluating the chemical compounds through the parameters used during the fermentation like: Ferment Type (FT) square and rectangular drawer, Removal Frequency (RF) 12 and 24 hours, Ear Endurance (EE) at zero and five days and the fermentation time (FTT) at the 0, 24, 48, 72 and 96 hours. The methodology consisted on a factorial arrangement 2 3 x 5 in where three factors were studied (TF, FR and AM), at two levels and the time of fermentation at five. The studied variables were: pH, acidity, tannins, sugars reducers and total of sugars. Results reflect for the cotyledon and pulp and testa makes a will bigger pH values and tannins in the rectangular fermenting and of acidity, sugars reducers and total in the square. The removal frequency each 24 hours, it showed bigger pH, sugars and tannins and littler acidity in the cotyledon and littler values in the pulp and testa makes a will and an increase in the sugars and tannins in this. The endurance determined an increment of the pH for five days and a descent of the acidity and sugars. In the pulp and testa makes a will the same tendency it was observed. With regard to the fermentation time, there was a variation of all the variables during the process for both fractions. These results are related with the final quality of chocolate

Cyclin-Dependent Kinase Inhibitor p21 Controls Adult Neural Stem Cell Expansion by Regulating Sox2 Gene Expression

In the adult brain, continual neurogenesis of olfactory neurons is sustained by the existence of neural stem cells (NSCs) in the subependymal niche. Elimination of the cyclin-dependent kinase inhibitor 1A (p21) leads to premature exhaustion of the subependymal NSC pool, suggesting a relationship between cell cycle control and long-term self-renewal, but the molecular mechanisms underlying NSC maintenance by p21 remain unexplored. Here we identify a function of p21 in the direct regulation of the expression of pluripotency factor Sox2, a key regulator of the specification and maintenance of neural progenitors. We observe that p21 directly binds a Sox2 enhancer and negatively regulates Sox2 expression in NSCs. Augmented levels of Sox2 in p21 null cells induce replicative stress and a DNA damage response that leads to cell growth arrest mediated by increased levels of p19(Arf) and p53. Our results show a regulation of NSC expansion driven by a p21/Sox2/p53 axis

A five-stage treatment train for water recovery from urine and shower water for long-term human Space missions

Long-term human Space missions will rely on regenerative life support as resupply of water, oxygen and food comes with constraints. The International Space Station (ISS) relies on an evaporation/condensation system to recover 74-85% of the water in urine, yet suffers from repetitive scaling and biofouling while employing hazardous chemicals. In this study, an alternative non-sanitary five-stage treatment train for one "astronaut" was integrated through a sophisticated monitoring and control system. This so-called Water Treatment Unit Breadboard (WTUB) successfully treated urine (1.2-L-d with crystallisation, COD-removal, ammonification, nitrification and electrodialysis, before it was mixed with shower water (3.4-L-d(-1)). Subsequently, ceramic nanofiltration and single-pass flat-sheet RO were used. A four-months proof-of-concept period yielded: (i) chemical water quality meeting the hygienic standards of the European Space Agency, (ii) a 87- +/- -5% permeate recovery with an estimated theoretical primary energy requirement of 0.2-kWh p -L-1, (iii) reduced scaling potential without anti-scalant addition and (iv) and a significant biological reduction in biofouling potential resulted in stable but biofouling-limited RO permeability of 0.5 L-m(-2)-h(-1)-bar(-1). Estimated mass breakeven dates and a comparison with the ISS Water Recovery System for a hypothetical Mars transit mission show that WTUB is a promising biological membrane-based alternative to heat-based systems for manned Space missions