Marília Lordêlo Cardoso Silva

Compostos fenólicos, carotenóides e atividade antioxidante em produtos vegetais

The respiratory process and several aerobic cells oxidative reactions lead to the formation of free radicals which contribute to the appearance of different diseases. The human cells depend on their antioxidant ability to provide protection against the prejudicial effects of free radical and reactive oxygen species that are inevitable consequences of aerobic life. Several epidemiologic studies indicate that high plant products ingestion is associated to a reduction in the hazard of a variety of cronical diseases such as arteriosclerosis and cancer. These effects have been specifically attributed to the plant compounds that have antioxidant activity: vitamin C and E, phenolic compounds, specially flavonoids, and carotenoids. 1

Lytic enzyme production optimization using low‐cost substrates and its application in the clarification of xanthan gum culture broth

Lytic enzymes are widely used in industrial biotechnology as they are able to hydrolyze the bacterial cell wall. One application of these enzymes is the clarification of the culture broth for the production of xanthan gum, because of its viability in viscous media and high specificity. The screening process for filamentous fungi producing lytic enzymes, the optimization of production of these enzymes by the selected microorganism, and the optimization of the application of the enzymes produced in the clarification of culture broth are presented in this article. Eleven fungal isolates were tested for their ability to produce enzymes able to increase the transmittance of the culture broth containing cells of Xanthomonas campestris. To optimize the secretion of lytic enzymes by the selected microorganism the following variables were tested: solid substrate, initial pH, incubation temperature, and addition of inducer (gelatin). Thereafter, secretion of the enzymes over time of incubation was assessed. To optimize the clarification process a central composite rotational design was applied in which the pH of the reaction medium, the dilution of the broth, and the reaction temperature were evaluated. The isolate identified as Aspergillus tamarii was selected for increasing the transmittance of the broth from 2.1% to 54.8%. The best conditions for cultivation of this microorganism were: use of coconut husk as solid substrate, with 90% moisture, at 30°C for 20 days. The lytic enzymes produced thereby were able to increase the transmittance of the culture broth from 2.1% to 70.6% at 65°C, without dilution and without pH adjustment.

Trametes villosa lignin peroxidase (TvLiP): genetic and molecular characterization.

White-rot basidiomycetes are the organisms that decompose lignin most efficiently, and Trametes villosa is a promising species for ligninolytic enzyme production. There are several publications on T. villosa applications for lignin degradation regarding the expression and secretion of laccase and manganese peroxidase (MnP) but no reports on the identification and characterization of lignin peroxidase (LiP), a relevant enzyme for the efficient breakdown of lignin. The object of this study was to identify and partially characterize, for the first time, gDNA, mRNA, and the corresponding lignin peroxidase (TvLiP) protein from T. villosa strain CCMB561 from the Brazilian semiarid region. The presence of ligninolytic enzymes produced by this strain grown in inducer media was qualitatively and quantitatively analyzed by spectrophotometry, qPCR, and dye fading using Remazol Brilliant Blue R. The spectrophotometric analysis showed that LiP activity was higher than that of MnP. The greatest LiP expression as measured by qPCR occurred on the 7th day, and the ABSA medium (agar, sugarcane bagasse, and ammonium sulfate) was the best that favored LiP expression. The amplification of the TvLiP gene median region covering approximately 50% of the T. versicolor LPGIV gene (87% identity); the presence of Trp199, Leu115, Asp193, Trp199, and Ala203 in the translated amplicon of the T. villosa mRNA; and the close phylogenetic relationship between TvLiP and T. versicolor LiP all indicate that the target enzyme is a lignin peroxidase. Therefore, T. villosa CCMB561 has great potential for use as a LiP, MnP, and Lac producer for industrial applications.

Applying structural transition theory to describe enzyme kinetics in heterogeneous systems

Enzyme action was investigated by assuming the occurrence of different states of enzyme-substrate affinities. These states were considered to involve enzyme species with distinct abilities to form reaction product. The results obtained showed strong agreement with the experimental data for the action of peroxidase. This approach provides a powerful tool for predicting the kinetic behavior of other enzymatic processes in conditions not described before. An additional feature of this approach is the ability to characterize processes at any enzyme-substrate concentration ratio, including high enzyme-substrate ratios and enzyme inhibition by substrate or product. This proposal can also be used in systems with heterogeneity concerning the investigated enzyme.

Cocoa pulp in beer production: Applicability and fermentative process performance

This work evaluated the effect of cocoa pulp as a malt adjunct on the parameters of fermentation for beer production on a pilot scale. For this purpose, yeast isolated from the spontaneous fermentation of cachaça (SC52), belonging to the strain bank of the State University of Feira de Santana-Ba (Brazil), and a commercial strain of ale yeast (Safale S-04 Belgium) were used. The beer produced was subjected to acceptance and purchase intention tests for sensorial analysis. At the beginning of fermentation, 30% cocoa pulp (adjunct) was added to the wort at 12°P concentration. The production of beer on a pilot scale was carried out in a bioreactor with a 100-liter capacity, a usable volume of 60 liters, a temperature of 22°C and a fermentation time of 96 hours. The fermentation parameters evaluated were consumption of fermentable sugars and production of ethanol, glycerol and esters. The beer produced using the adjunct and yeast SC52 showed better fermentation performance and better acceptance according to sensorial analysis.