Corn Cob as a Green Support for Laccase Immobilization-Application on Decolorization of Remazol Brilliant Blue R.

The high demand for food and energy imposed by the increased life expectancy of the population has driven agricultural activity, which is reflected in the larger quantities of agro-industrial waste generated, and requires new forms of use. Brazil has the greatest biodiversity in the world, where corn is one of the main agricultural genres, and where over 40% of the waste generated is from cobs without an efficient destination. With the aim of the valorization of these residues, we proposed to study the immobilization of laccase from Aspergillus spp. (LAsp) in residual corn cob and its application in the degradation of Remazol Brilliant Blue R (RBBR) dye. The highest yields in immobilized protein (75%) and residual activity (40%) were obtained at pH 7.0 and an enzyme concentration of 0.1 g.mL-1, whose expressed enzyme activity was 1854 U.kg-1. At a temperature of 60 °C, more than 90% of the initial activity present in the immobilized biocatalyst was maintained. The immobilized enzyme showed higher efficiency in the degradation (64%) of RBBR dye in 48 h, with improvement in the process in 72 h (75%). The new biocatalyst showed operational efficiency during three cycles, and a higher degradation rate than the free enzyme, making it a competitive biocatalyst and amenable to industrial applications.

Biosorption Cu (II) by the yeast Saccharomyces cerevisiae.

With the industrial and population advances, the generation of effluents containing heavy metals has grown a lot. In this work, the commercial biomass of the yeast Saccharomyces cerevisiae Perlage® BB were carried out as Cu (II) ion biosorbent. The influence of some variables such as metal concentration, pH range, equilibrium time and biomass concentration were evaluated. The biosorption capacity was measured by adsorption isotherms, with the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) models. The characterization of the biomass surface were investigated by Dispersive Energy X-Ray Fluorescence Spectrometry (EDX) and Atomic Force Microscopy (AFM). The results showed that the biomass presented good biosorption efficiency. The best fit of the data was obtained with the Langmuir model, detecting the maximum biosorption capacity of 4.73 mg g-1. By the methods used in the characterization of the biomass surface, it was possible to verify the presence of the Cu (II) ion in the yeast.

Reduction of ßN-alkanoyl-5-hydroxytryptamides and diterpenes by yeast supplementation to green coffee during wet processing.

Coffee is one of the most consumed non-alcoholic beverages in the world. It is well known that some compounds present in coffee beans have important biological activities. In this study, evidence was turned to ßN-alkanoyl-5-hydroxytryptamides (C-5HTs) and to the furokaurane diterpenes cafestol and kahweol, associated with gastric irritation and increasing of blood cholesterol, respectively. Fermentation in coffee post-harvest wet process was induced by three Saccharomyces cerevisiae yeasts (for bakery, white and sparkling wines) as starter cultures. Variations in mass, time, temperature and pH (56 experiments under fractional factorial and mixture experimental designs) were tested. Substantial reductions for C-5HTs (up to 38% reduction for C20-5HT and 26% for C22-5HT) as well as for diterpenes (54% for cafestol and 53% for kahweol) were obtained after treating green coffee beans with 0.6 g of a 1:1:1 mixture the three yeasts for 12 h at 15 °C and pH 4. Caffeine and 5-CQA content, monitored in the green coffee beans, did not change. Therefore, the use of starter cultures during coffee post-harvest wet process has influence on the amount of some important compounds related to health and improves the sensory quality of the beverage.

Palm oil hydrolysis catalyzed by lipases under ultrasound irradiation--the use of experimental design as a tool for variables evaluation.

Diacylglycerol oil has been increasingly recognized by its good nutritional properties and therefore, different technologies have been developed for obtaining it. The present work focuses on the diacylglycerol production by hydrolysis reaction of the palm oil using the PS IM and TL IM commercial lipases as biocatalysts under ultrasound irradiation. An experimental design (central composite rotatable design--CCRD) adopting surface response was applied as a tool to evaluate the optimal reaction conditions beyond a restrict number of experiments. Reactions were performed in an ultrasound equipment and different variables were investigated, such as temperature (30-55 °C), enzyme content (1-2 wt.% of oil mass), mechanical stirring (300-700 rpm) and reaction time. Both, PS IM and TL IM enzymes showed the best results after 1h and 30 min of reaction under 30 °C and, applying 300 rpm as stirring. On these conditions, the diacylglycerol yield was around 34% and 39%, respectively; considering that 1% PS IM was applied for the first one and, 2% TL IM for the second one. Therefore, it was obtained good yield of a diacylglycerol-rich oil in shorter reaction times under sonication and soft conditions. The mathematic model proposed suggested a satisfactorily representation of the process and good correlation among the experimental results and the theoretical values predicted by the model equation were achieved.

Optimization of 2-ethylhexyl palmitate production using lipozyme RM IM as catalyst in a solvent-free system.

This work reports the application of a lipase in the 2-ethylhexyl palmitate esterification in a solvent-free system with an immobilized lipase (Lipozyme RM IM). A sequential strategy was used applying two experimental designs to optimize the 2-ethylhexyl palmitate production. An empirical model was then built so as to assess the effects of process variables on the reaction conversion. Afterwards, the operating conditions that optimized 2-ethylhexyl palmitate production were established as being acid/alcohol molar ratio 1:3, temperature of 70 degrees C, stirring rate of 150 rpm, 10 wt.% of enzyme, leading to a reaction conversion as high as 95%. From this point, a kinetic study was carried out evaluating the effect of acid:alcohol molar ratio, the enzyme concentration and the temperature on product conversion. The results obtained in this step permit to verify that an excess of alcohol (acid to alcohol molar ratio of 1:6), relatively low enzyme concentration (10 wt.%) and temperature of 70 degrees C, led to conversions next to 100%.

Lipase-catalyzed diacylglycerol production under sonochemical irradiation.

The present paper describes a protocol for production of diacylglycerol by the partial hydrolysis of soybean oil catalyzed by lipase under ultrasound irradiation. Better yields and shorter reaction times were obtained under sonication as compared to the thermal process.

Assessment of process variables on 2-ethylhexyl palmitate production using Novozym 435 as catalyst in a solvent-free system.

This work reports the optimization of 2-ethylhexyl palmitate production by esterification reaction in a solvent-free system using a commercial lipase as catalyst. For this, a sequential strategy was performed applying three experimental designs. An empirical model was built so as to assess the effects of process variables on the reaction conversion. Afterward, the operating conditions that optimized 2-ethylhexyl palmitate production were determined to be acid to alcohol molar ratio of 1:5.5, 70 degrees C, 150 rpm and 10.5 wt% of enzyme, leading to a reaction conversion as high as 93%. From this point, a kinetic study was carried out evaluating the influence of acid to alcohol molar ratio, enzyme concentration and temperature on product yield. Results obtained in this step allow to conclude that an excess of alcohol (acid to alcohol molar ratio of 1:6), relatively low enzyme concentration (10 wt%) and temperature of 70 degrees C led to nearly complete reaction conversion.

Salicylic acid degradation from aqueous solutions using Pseudomonas fluorescens HK44: parameters studies and application tools

The optimal conditions for salicylic acid biodegradation by Pseudomonas fluorescens HK44 were determined in this study with the intention to create a microbial sensor. Kinetic experiments permitted a definition of 60 and 30min the time needed to achieve the maximum degradation of salicylic acid presented in a medium with and without yeast extract, respectively. The degradation in medium without yeast extract and the quantification by spectrophotometry 230 nm were selected to be used in further tests. The use of preactivated cells or on the exponential growth phase showed better salicylic acid degradation percentages when compared to nonactivated cells or on the stationary growth state. Finally, the best cellular concentration used on the salicylic acid degradation was 0,1 g.L-1. Strain HK44 shows to be capable of degrade salicylic acid presented in simple aqueous systems, making this strain a promising tool for the application on a luminescent microbial sensor.

Com a intenção de criar um sensor microbiano, as condições ótimas para a biodegradação de ácido salicílico por Pseudomonas fluorescens HK44 foram determinadas neste estudo. Os experimentos cinéticos permitiram a definição dos tempos de 60 e 30 minutos como necessários para atingir a máxima degradação de ácido salicílico presente em meio com ou sem extrato de lêvedo, respectivamente. A degradação no meio sem extrato de lêvedo e a quantificação através de espectrofotometria 230 nm foram selecionadas para serem utilizadas em testes posteriores. O uso de células pré-ativadas ou na fase exponencial de crescimento apresentou melhores porcentagens de degradação de ácido salicílico quando comparadas a células não-ativadas ou no estado estacionário de crescimento. Além disso, a melhor concentração celular utilizada nessa degradação foi 0,1 g.L¹. A cepa HK44 parece ser capaz de degradar o ácido salicílico presente em sistemas aquosos simples, tornando este microrganismo uma ferramenta promissora para aplicação em um sensor microbiano luminescente.

Protease production by Streptomyces sp. isolated from Brazilian Cerrado soil: optimization of culture medium employing statistical experimental design.

Streptomyces are important microorganisms because of their capacity to produce numerous bioactive molecules. In the present work protease production, by Streptomyces sp. 594 isolated from a Brazilian Cerrado soil, was maximized by optimizing a low-cost culture medium composition (casitone and sugarcane molasses) using statistical experimental design. The final protease activity (56 U/mL) was 2.8-fold and 58-fold higher than that obtained in the beginning of this study, and in a previous work, using an actinomycete selection medium, respectively. Protease production, not growth associated, appeared to be modulated by an inducer system, whereby the C/N ratio seemed to play a significant role.

Factors involved with cadmium absorption by a wild-type strain of Saccharomyces cerevisiae

At the concentration used in this work (10 ppm), cadmium was efficiently removed from the environment by stationary yeast cells. While exponential phase cells showed low capacity of cadmium absorption, stationary cells removed 97 percent of the original metal in 24 hours. Total cadmium absorption shown by dry cells was lower than that of fresh ones, although both cells removed 50 percent of metal during the first hour of treatment. We also verified that only viable cells were capable of absorbing cadmium. Independently of the growth phase, cells showed high tolerance to 10 ppm CdSO4 and about 80 percent of cells remained viable after 24 hours exposure to cadmium. However, when stationary phase cells were previously dehydrated and then exposed to cadmium, they exhibited poor survival. By using an oxidation-dependent fluorescent probe, we observed that, once absorbed by cells, cadmium increases the intracellular level of oxidation, which may be responsible for its toxic effect. Crude extracts from stationary phase cells exposed to cadmium showed a 10-fold increase in fluorescence, while extracts from cells of exponential phase did not increase in fluorescence. Dry cells treated with the metal showed a high increase in fluorescence, mainly caused by dehydration.

Selection of tannase-producing Aspergillus niger strains

The aim of this work was to select strains of Aspergillus niger for tannase production. Growth of colonies in plates with tannic acid-containing medium indicated their ability to synthesize tannase. Tannase activity was also measured in solid-state fermentation. A. niger 11T25A5 was the best tannase producer (67.5 U.g-1/72 hours of fermentation.

Partial purification of a polygalacturonase produced by solid-state cultures of Aspergillus niger 3T5B

A poligalacturonase produzida em cultura semi sólida de Aspergillus niger 3T5B8 foi purificada usando fracionamento por adiçäo de sal (salting out), diálise e cromatografia de gel-filtraçäo. A adiçäo de sulfato de amônio em diferentes níveis de saturaçäo apresentaram um compromisso entre purificaçäo e recuperaçäo da atividade enzimática. A cromatografia por gel-filtraç o forneceu bons resultados quando azida de sódio foi utilizada nos tampöes de eluiçäo, diminuindo as perdas na atividade enzimática em 14 por cento. O peso molecular determinado para esta poligalacturonase foi de 34700 daltons

The effect of alginic matrix on cadmium uptake by an immobilized green microalgae

Este trabalho descreve alguns estudos de absorçäo de cádmio por células de Chlorella homosphaera livres e imobilizadas em alginato, bem como a absorçäo devida à matriz polimérica isenta de células em soluçöes de cádmio na faixa de concentraçöes de 8,7 a 45,0 mg/l. A captaçäo do metal foi mais efetiva com o uso de células livres até a concentraçäo de 26,8 mg/l do metal. Os resultados obtidos com emprego do alginato e células aprisionadas em alginato estäo provavelmente associados à porosidade da matriz e à densidade celular dentro das partículas de alginato

Captaçäo do cádmio e seu efeito no crescimento de chlorella homosphaera e Scenedesmus quadricauda em condiçöes laboratorias / Cadmium uptake and its effect on the growth of chlorella homosphaera and scenedesmus quadricauda cells in laboratory conditions

resumo:O efeito tóxico e a captaçäo de captaçäo de cádmio durante o crescimento de Chlorella homosphaera e Scenedesmus quadricauda foram estudados em diferentes concentraçöes de 4 mg/l e 2 mg/l, respectivamente.Para as duas espécies estudadas, este efeito foi diretamente proporcional à concentraçäo do metal e, inversamente proporcinal à concentraçäo celular