Marceli Fernandes Silva

Enzymatic synthesis of fructooligosaccharides by inulinases from Aspergillus niger and Kluyveromyces marxianus NRRL Y-7571 in aqueous–organic medium

This work is focused on the synthesis of the fructooligosaccharides (FOS) from sucrose and inulin, using free, immobilized and pre-treated immobilized inulinase from Kluyveromyces marxianus NRRL Y 7571 and Aspergillus niger in an aqueous-organic system. Initially, the influence of pre-treatment using four different gases, propane, n-butane, CO(2) and liquefied petroleum gas (LPG), was investigated towards FOS production and best results were found when both enzymes were previously treated with LPG. The best reaction yields were obtained when the immobilized enzymes were treated with LPG. Considering FOS synthesis using the enzyme from A. niger, yields of 26.62% of GF2 (kestose), 30.62% of GF3 (nystose) and 8.47% of GF4 (fructosyl nystose) were achieved using sucrose as substrate. Using inulinases from K. marxianus NRRL Y 7571, 11.89% of GF2 and 20.83% of GF3 were obtained, using inulin as substrate. However, promising results were achieved using the free form of inulinase from A. niger (77.19% of GF2; 14.03% of GF3 and 0.07% of GF4) using inulin as substrate.

Hybrid modeling of xanthan gum bioproduction in batch bioreactor

This work is focused on hybrid modeling of xanthan gum bioproduction process by Xanthomonas campestris pv. mangiferaeindicae. Experiments were carried out to evaluate the effects of stirred speed and superficial gas velocity on the kinetics of cell growth, lactose consumption and xanthan gum production in a batch bioreactor using cheese whey as substrate. A hybrid model was employed to simulate the bio-process making use of an artificial neural network (ANN) as a kinetic parameter estimator for the phenomenological model. The hybrid modeling of the process provided a satisfactory fitting quality of the experimental data, since this approach makes possible the incorporation of the effects of operational variables on model parameters. The applicability of the validated model was investigated, using the model as a process simulator to evaluate the effects of initial cell and lactose concentration in the xanthan gum production.

Aspergillus niger inulinase immobilized in polyurethane foam and treated in pressurized LPG: A potential catalyst for enzymatic synthesis of fructooligosaccharides

Abstract Inulinase from Aspergillus niger was immobilized in polyurethane foam (PU). Immobilized catalyst was treated in pressurized liquefied petroleum gas (LPG) system. This biocatalyst was used in the fructooligosaccharide production using sucrose as substrate in aqueous system. The main objective of this study was to evaluate the reaction yield and productivity by using polyurethane foam as a low-cost support for enzyme immobilization in an alternative processes for fructooligosaccharide production in pressurized LPG system with potential for industrial application. The total FOS concentration obtained were 31% as a result of sucrose concentration reduction, and formation of FOS long chain (GF3 and GF4) from kestose (GF2). FOS concentrations of 5%, 22%, and 3% were obtained for GF2, GF3, and GF4, respectively. The methodology suggested in this research work, enzyme immobilization in a low-cost support, and treatment in LPG, showed potential technology for fructooligosaccharide synthesis.

A new approach to evaluate immobilization of β-galactosidase on Eupergit® C: structural, kinetic, and thermal characterization

This study aimed to evaluate β-galactosidase immobilization. For this purpose, the ionic strength of the buffer, reaction time, amount of the immobilization support, and pH were evaluated by a central composite design. Assay 8, which consisted of 1.5 mol L-1 phosphate buffer (pH 7.5) and a reaction time of 2 h, produced the maximum yield. Eupergit® C (400 mg) was subsequently used as an immobilization support. Immobilization kinetics wereinvestigated, and a significant increase in the yield was obtained after immobilization compared with that obtained from assay 8 (22.0 U mL-1 vs. 15.6 U mL-1). The enzyme efficiency of actuation was evaluated using o-nitrophenyl-β-D-galactopyranoside and lactose, with lactose providing better results. The reuse of β-galactosidase was evaluated, and more than 50% of the initial enzyme activity was maintained after five cycles of use. Enzyme characterization revealed that immobilization improved some aspects of the thermostability of β-galactosidase.

Purification of inulinases by changing the ionic strength of the medium and precipitation with alcohols

The present study evaluated the purification of inulinase by changing the ionic strength of the medium by addition of NaCl and CaCl2 followed by precipitation with n-propyl alcohol or iso-propyl alcohol. The effects of the concentration of alcohols and the rate of addition of alcohols in the crude extract on the purification yield and purification factor were evaluated. Precipitation caused an activation of enzyme and allowed purification factors up to 2.4-fold for both alcohols. The purification factor was affected positively by the modification of the ionic strength of the medium to 0.5 mol.L-1 NaCl before precipitation with the alcohol (n-propyl or iso-propyl). A purification factor of 4.8-fold and an enzyme yield of 78.1 % could be achieved by the addition of 0.5 mol.L-1 of NaCl to the crude extract, followed by the precipitation with 50 % (v/v) of n-propyl alcohol, added at a flow rate of 19.9 mL/min.

Formulation of chicken sausages with broiler blood proteins and dye

Dye and proteins recovered from broiler blood were used in the formulation of chicken sausages in substitution of soy proteins and synthetic dyes. Three formulations of chicken sausages were prepared: standard, liquid plasma, and freeze-dried plasma. The application of protein and blood dye in the formulation of sausages and sensory analysis followed the Brazilian legislation. Physicochemical, microbiological and sensory attributes of sausages were evaluated during 60. All the formulations met the physicochemical and microbiological requirements. Considering the sensory analysis, sausages prepared using freeze-dried plasma presented significant difference from the standard sausage. There was no significant difference in the acceptance between the standard and liquid plasma sausages. Therefore, the use of such byproducts can add value to meat products without any adverse effect consumers acceptability.

Interference of salts used on aqueous two-phase systems on the quantification of total proteins.

In this study the interference of potassium phosphate, sodium citrate, sodium chloride and sodium nitrate salts on protein quantification by Bradfords method was assessed. Potassium phosphate and sodium citrate salts are commonly used in aqueous two-phase systems for enzyme purification. Results showed that the presence of potassium phosphate and sodium citrate salts increase the absorbance of the samples, when compared with the samples without any salt. The increase in absorptivity of the solution induces errors on protein quantification, which are propagated to the calculations of specific enzyme activity and consequently on purification factor. The presence of sodium chloride and sodium nitrate practically did not affect the absorbance of inulinase, probably the metals present in the enzyme extract did not interact with the added salts.

Produção de lipases de Aspergillus niger e Aspergillus fumigatus através de fermentação em estado sólido, avaliação da especificidade do substrato e seu uso em reações de esterificação e alcoólise: evaluation of substrate specificity and use in esterification and alcoholysis reactions

Christian Oliveira Reinehra, Juliana Rizzardia, Marceli Fernandes Silvaa, Debora de Oliveiraa, Helen Treichelb e Luciane Maria Colla*,c Universidade Regional Integrada do Alto Uruguai e das Missoes, Av. Sete de Setembro, 1621, 99700-000 Erechim – RS, Brasil Universidade Federal da Fronteira Sul, Campus de Erechim, Av. Dom Joao Hoffmann, 313, 99700-000 Erechim – RS, Brasil Universidade de Passo Fundo, BR 285, Bairro Sao Jose, 99052-900 Passo Fundo – RS, Brasil

Production of lipases with Aspergillus niger and Aspergillus fumigatus through solid state fermentation: evaluation of substrate specificity and use in esterification and alcoholysis reactions.

Christian Oliveira Reinehra, Juliana Rizzardia, Marceli Fernandes Silvaa, Debora de Oliveiraa, Helen Treichelb e Luciane Maria Colla*,c Universidade Regional Integrada do Alto Uruguai e das Missoes, Av. Sete de Setembro, 1621, 99700-000 Erechim – RS, Brasil Universidade Federal da Fronteira Sul, Campus de Erechim, Av. Dom Joao Hoffmann, 313, 99700-000 Erechim – RS, Brasil Universidade de Passo Fundo, BR 285, Bairro Sao Jose, 99052-900 Passo Fundo – RS, Brasil

Production of lipases with Aspergillus niger and Aspergillus fumigatus through solid state fermentation

Christian Oliveira Reinehra, Juliana Rizzardia, Marceli Fernandes Silvaa, Debora de Oliveiraa, Helen Treichelb e Luciane Maria Colla*,c Universidade Regional Integrada do Alto Uruguai e das Missoes, Av. Sete de Setembro, 1621, 99700-000 Erechim – RS, Brasil Universidade Federal da Fronteira Sul, Campus de Erechim, Av. Dom Joao Hoffmann, 313, 99700-000 Erechim – RS, Brasil Universidade de Passo Fundo, BR 285, Bairro Sao Jose, 99052-900 Passo Fundo – RS, Brasil