To analyze mortality rates of children with severe sepsis and septic shock in relation to time-se... more To analyze mortality rates of children with severe sepsis and septic shock in relation to time-sensitive fluid resuscitation and treatments received and to define barriers to the implementation of the American College of Critical Care Medicine/Pediatric Advanced Life Support guidelines in a pediatric intensive care unit in a developing country. Retrospective chart review and prospective analysis of septic shock treatment in a pediatric intensive care unit of a tertiary care teaching hospital. Ninety patients with severe sepsis or septic shock admitted between July 2002 and June 2003 were included in this study. Of the 90 patients, 83% had septic shock and 17% had severe sepsis; 80 patients had preexisting severe chronic diseases. Patients with septic shock who received less than a 20-mL/kg dose of resuscitation fluid in the first hour of treatment had a mortality rate of 73%, whereas patients who received more than a 40-mL/kg dose in the first hour of treatment had a mortality rate of 33% (P < 0.05). Patients treated less than 30 minutes after diagnosis of severe sepsis and septic shock had a significantly lower mortality rate (40%) than patients treated more than 60 minutes after diagnosis (P < 0.05). Controlling for the risk of mortality, early fluid resuscitation was associated with a 3-fold reduction in the odds of death (odds ratio, 0.33; 95% confidence interval, 0.13-0.85). The most important barriers to achieve adequate severe sepsis and septic shock treatment were lack of adequate vascular access, lack of recognition of early shock, shortage of health care providers, and nonuse of goals and treatment protocols. The mortality rate was higher for children older than 2 years, for those who received less than 40 mL/kg in the first hour, and for those whose treatment was not initiated in the first 30 minutes after the diagnosis of septic shock. The acknowledgment of existing barriers to a timely fluid administration and the establishment of objectives to overcome these barriers may lead to a more successful implementation of the American College of Critical Care Medicine guidelines and reduced mortality rates for children with septic shock in the developing world.
OBJETIVO: Analisar os indicadores de mortalidade para doenças cardiovasculares em São José do Rio... more OBJETIVO: Analisar os indicadores de mortalidade para doenças cardiovasculares em São José do Rio Preto, no estado de São Paulo e no Brasil e avaliar os coeficientes de mortalidade segundo níveis socioeconômicos da população do município. MÉTODOS: Utilizaram-se informações sobre mortalidade por doenças cardiovasculares e de população do Sistema de Informações de Mortalidade e do Departamento de Informação e Informática do Sistema Único de Saúde. Calcularam-se coeficientes padronizados de mortalidade e mortalidade proporcional por doenças cardiovasculares. Gerou-se mapa temático dos setores censitários da área urbana do município agrupados segundo níveis socioeconômicos, apresentado com os respectivos coeficientes. RESULTADOS: Os coeficientes de mortalidade para o município, o estado e o país decresceram de 1980 a 2002. Em 2003, o coeficiente do município foi de 195,9 óbitos por 100.000 habitantes, a mortalidade proporcional foi de 31,3% e as três principais causas de morte foram a doença cerebrovascular, o infarto e a doença hipertensiva. O coeficiente de mortalidade da população correspondente ao grupo de setores censitários com o pior nível socioeconômico foi 40% superior ao com o melhor nível. CONCLUSÃO: O coeficiente de mortalidade por doenças cardiovasculares decresceu nas três áreas geográficas analisadas. Do total de óbitos ocorridos em São José do Rio Preto em 2003, aproximadamente um terço foi por este grupo de doenças. A área com nível socioeconômico menos favorecido apresentou o maior coeficiente de mortalidade.
The mechanisms by which macromolecules are transported through the cell wall of fungi are not kno... more The mechanisms by which macromolecules are transported through the cell wall of fungi are not known. A central question in the biology of Cryptococcus neoformans, the causative agent of cryptococcosis, is the mechanism by which capsular polysaccharide synthesized inside the cell is exported to the extracellular environment for capsule assembly and release. We demonstrate that C. neoformans produces extracellular vesicles during in vitro growth and animal infection. Vesicular compartments, which are transferred to the extracellular space by cell wall passage, contain glucuronoxylomannan (GXM), a component of the cryptococcal capsule,
Inulinase is an enzyme relevant to fructose production by enzymatic hydrolysis of inulin. This en... more Inulinase is an enzyme relevant to fructose production by enzymatic hydrolysis of inulin. This enzyme is also applied in the production of fructo-oligosaccharides that may be used as a new food functional ingredient. Commercial inulinase is currently obtained using inulin as substrate, which is a relatively expensive raw material. In Brazil, the production of this enzyme using residues of sugarcane and corn industry (sugarcane bagasse, molasses, and corn steep liquor) is economically attractive, owing to the high amount and low cost of such residues. In this context, the aim of this work was the assessment of inulinase production by solid state fermentation using by Kluyveromyces marxianus NRRL Y-7571. The solid medium consisted of sugar cane bagasse supplemented with molasses and corn steep liquor. The production of inulinase was carried out using experimental design technique. The effect of temperature, moisture, and supplements content were investigated. The enzymatic activity reached a maximum of 445 units of inulinase per gram of dry substrate.
This work reports the production of monoacylglycerols (MAGs) from olive oil in pressurized propan... more This work reports the production of monoacylglycerols (MAGs) from olive oil in pressurized propane as solvent medium. For this purpose a commercial immobilized lipase (Novozym 435) was employed as catalyst and sodium (bis-2-ethyl-hexyl) sulfosuccinate (Aerosol-OT or AOT) as surfactant. The experiments were conducted in the batch mode keeping constant the glycerol to oil molar ratio of 2:1, propane to substrates mass ratio of 4:1, enzyme concentration (by weight of substrates) at 10 wt%, and agitation of 600 rpm, varying the temperature, pressure, and AOT concentration. Results showed that lipase-catalyzed glycerolysis in compressed propane might be a potential route to conventional methods, as high contents of reaction products, MAG and DAG, were achieved at mild temperature and pressure conditions (30 • C and 30 bar) with a low solvent to substrates mass ratio (4:1) in short-reaction times (1 h).
The cheese whey is an abundant residue obtained during the cheese processing and its disposal in ... more The cheese whey is an abundant residue obtained during the cheese processing and its disposal in the environment causes several drawbacks. The bioconversion of this by-product in added-value products is an important alternative to overcome this environmental problem. In this work, the feasibility of using cheese whey as carbon source for xanthan gum production was investigated using two strains of Xanthomonas campestris. The cheese whey:sucrose ratio and the supplementation of the medium were investigated by a Central Composite Design (CCD) in order to improve the xanthan gum production. Maximum xanthan gum productions were observed after 72 h using cheese whey as sole carbon source, 0.1% (w/v) MgSO 4 Â 7H 2 O and 2.0% (w/v) of K 2 HPO 4 , yielding approximately 25 g L À1 . This value is quite higher than some results presented in the literature using glucose as substrate. Although the production was similar for the two strains, chemical composition and ionic strength presented several differences in chemical characteristics between the polysaccharides produced.
Current studies about lipase production by solid-state fermentation involve the use of agro-indus... more Current studies about lipase production by solid-state fermentation involve the use of agro-industrial residues towards developing cost-effective systems directed to large-scale commercialization of enzyme-catalyzed processes. In this work, lipase production and partial characterization of the crude enzymatic extracts obtained by Penicillium verrucosum using soybean bran as substrate was investigated. Different inductors were evaluated and the results showed that there is no influence of this variable on the lipase production, while temperature and initial moisture were the main factors that affected enzyme production. The optimized cultivation temperature (27.5 °C) and initial moisture of substrate (55%) were determined using the response surface methodology. Kinetics of lipase production was followed at the optimized growth conditions. Optimum lipase yield was 40 U/g of dry bran. The crude enzymatic extract showed optimal activity in the range from 30 to 45 °C and in pH 7.0.
This review paper provides an overview regarding the main aspects of microbial lipases production... more This review paper provides an overview regarding the main aspects of microbial lipases production. The most important microbial lipase-producing strains for submerged and solid-state fermentations are reviewed as well as the main substrates, including the use of agroindustrial residues. Current process techniques (batch, repeated-batch, fed-batch, and continuous mode) are discussed and the main bioreactors configurations are also presented. Furthermore, the present review paper shows a general overview about the development of mathematical models applied to lipase production. Finally, some future perspectives on lipase production are discussed with special emphasis on lipase engineering and the use of mathematical models as a useful tool for process improvement and control.
The production of lipases by Penicillium simplicissimum using solid-state fermentation and soy ca... more The production of lipases by Penicillium simplicissimum using solid-state fermentation and soy cake as substrate was investigated. The effects of temperature, cake moisture, and carbon supplementation on lipase production were studied using a two-level experimental plan. Moisture, pH, and lipase activity were followed during fermentation. Statistical analysis of the results was performed to evaluate the effect of the studied variables on the maximum lipase activity. Incubation temperature was the variable that most affected enzyme activity, showing a negative effect. Moisture and carbon supplementation presented a positive effect on activity. It was possible to obtain lipase activity as high as 21 U/g of dry cake in the studied range of process variables.
This work investigates the production of fatty acid ethyl esters (FAEE) from soybean oil in compr... more This work investigates the production of fatty acid ethyl esters (FAEE) from soybean oil in compressed propane using Novozym 435 as catalyst. The experiments were performed in a batch reactor following the kinetics of the enzyme-catalyzed reaction in the temperature range of 35-65 • C, from 50 to 150 bar, enzyme concentration of 1-20 wt%, oil to ethanol molar ratio of 1:3-1:15 and solvent to substrates mass ratio of 1:1-4:1. Results showed that lipase-catalyzed alcoholysis in propane might be a potential alternative to conventional techniques for biodiesel production as complete conversions were obtained at mild temperature and pressure conditions, 65 • C and 50 bar, for an enzyme concentration of 5 wt% in 6 h of reaction.
This work investigates the influence of temperature, pressure, exposure times and depressurizatio... more This work investigates the influence of temperature, pressure, exposure times and depressurization rate on the activity of two commercial immobilized lipases submitted to compressed carbon dioxide, propane and n-butane. A high-pressure cell was employed in the experiments, varying the temperature from 35 to 75 • C, in the pressure range of 10-280 bar, exposure times from 1 to 6 h and adopting distinct decompression rates. Results showed that activity losses were verified for Lipozyme IM in all compressed solvents, markedly in carbon dioxide. For Novozym 435, treatment in carbon dioxide though in less extent also led to activity losses, while the use of propane and n-butane promoted enhancements of the enzyme activity. In general, within the range studied, temperature and exposure times affected positively enzyme activity while the decompression rates did not demonstrate to be a relevant variable. Additionally, an exploratory study was conducted to investigate the effect of compression/expansion cycles on enzyme activity in all solvents. Thermogravimetric analyses show that the thermal profiles of Novozym 435 treated in n-butane and in carbon dioxide are similar to the untreated enzyme. Scanning electron micrographs of Novozym 435 illustrate that the material submitted to carbon dioxide presented morphological alterations when compared to the untreated enzyme.
Recently, the use of supercritical CO 2 (SCCO 2 ) as a solvent in enzyme-catalyzed reactions has ... more Recently, the use of supercritical CO 2 (SCCO 2 ) as a solvent in enzyme-catalyzed reactions has been a matter of considerable research because of its favorable transport properties that can accelerate mass-transfer-limited enzymatic reactions. Further, biocatalysts, especially lipases, have substrate specificity and catalyze the syntheses of esters from a variety of acids and alcohols in SCCO 2 . Fatty acid esters obtained from alcoholysis of vegetable oils have many applications, such as antifriction agents, food preservatives, and emulsifiers. However, despite the industrial importance of the products obtained from alcoholysis of vegetable oils, conversions of such reactions in SCCO 2 have hardly been reported in the literature. Hence, the main objective of this work is to study the ethanolysis of palm kernel oil in SCCO 2 as catalyzed by two commercial lipases. The experiments were performed in a reactor vessel in the temperature range of 40-70°C and from 60 to 200 bar using a water concentration of 0-10 wt % and oil/ethanol molar ratios from 1:3 to 1:10. The initial reaction rate was found to be a function of both pressure and the oil/ethanol molar ratio. A simple model, capable of representing the conversion-time relationship curve, is proposed.
This work investigated the influence of temperature, pressure, exposure times and depressurizatio... more This work investigated the influence of temperature, pressure, exposure times and depressurization rate on the activity of a non-commercial immobilized lipase from Yarrowia lipolytica (YLL) submitted to compressed carbon dioxide, propane and n-butane. A high-pressure cell was employed in the experiments, in the pressure range of 10–280bar, varying the temperature from 35 to 75°C, exposure times from 1 to 6h,
... Also, to the best of our knowledge, there is no comprehensive study available comparing conve... more ... Also, to the best of our knowledge, there is no comprehensive study available comparing conventional and supercritical media for this reaction. ... For this purpose, a Taguchi experimentaldesign with two levels and four variables was adopted for each system to allow the ...
This article reports experimental data on the production of fatty acid ethyl esters from refined ... more This article reports experimental data on the production of fatty acid ethyl esters from refined and degummed soybean oil and castor oil using NaOH as catalyst. The variables investigated were temperature (30–70°C), reaction time (1–3 h), catalyst concentration (0.5–1.5 w/wt%), and oil-to-ethanol molar ratio (1:3–1:9). The effects of process variables on the reaction conversion as well as the optimum experimental conditions are presented. The results show that conversions >95% were achieved for all systems investigated. In general, an increase in reaction temperature, reaction time, and in oil-to-ethanol molar ratio led to an enhancement in reaction conversion, whereas an opposite trend was verified with respect to catalyst concentration.
This work investigates the continuous production of fatty acid ethyl esters from soybean oil in c... more This work investigates the continuous production of fatty acid ethyl esters from soybean oil in compressed fluids, namely carbon dioxide, propane and n-butane, using immobilized Novozym 435 as catalyst. The experiments were performed in a packed-bed bioreactor evaluating the effects of temperature in the range of 30-70°C, from 50 to 150 bar, oil to ethanol molar ratio of 1:6-1:18 and solvent to substrates mass ratio of 4:1-10:1. In contrast to the use of carbon dioxide and n-butane, results showed that lipasecatalyzed alcoholysis in a continuous tubular reactor in compressed propane might be a potential route to biodiesel production as high reaction conversions were achieved at mild temperature (70°C) and pressure (60 bar) conditions in short reaction times.
The objective of this work was to assess the influence of compressed CO 2 on the specific activit... more The objective of this work was to assess the influence of compressed CO 2 on the specific activity of peroxidase (POD) from radish (Raphanus sativus L.). The protein concentrate, in phosphate buffer, was obtained through the precipitation of proteins with (NH 4 ) 2 SO 4 . The peroxidase activity was determined using guaiacol as substrate. A semi-factorial experimental design was adopted to evaluate the effects of temperature (30-50 • C), exposure time (1-6 h), carbon dioxide density (ρ R = 0.6-1.8, resulting in pressures from 70.5 to 254.4 bar), and depressurization rate (10-200 kg/m 3 /min) on the peroxidase activity. Samples of lyophilized proteic concentrate were also submitted to high pressure and the effect of water content on the enzymatic activity in compressed CO 2 was studied. The water content in lyophilized samples was determined by thermogravimetric analysis. The results showed that the treatment of the enzymatic concentrate with CO 2 at high pressure could be a promising route to increase the POD activity.
The main objective of this work was to investigate the biotransformations of (−)α-pinene, (−)β-pi... more The main objective of this work was to investigate the biotransformations of (−)α-pinene, (−)β-pinene, and (+) limonene by Aspergillus niger ATCC 9642. The culture conditions involved—concentration of cosolvent (EtOH), substrate applied, and sequential addition of substrates—were investigated. Adaptation of the precultures with small amounts of substrate was also studied. The experiments were performed in conical flasks with liquid cultures. This strain of A. niger was able to convert only (−)β-pinene into α-terpineol. An optimum conversion of (−)β-pinene into α-terpineol of about 4% was obtained when the substrate was applied as a diluted solution in EtOH and sequential addition of substrate was used.
To analyze mortality rates of children with severe sepsis and septic shock in relation to time-se... more To analyze mortality rates of children with severe sepsis and septic shock in relation to time-sensitive fluid resuscitation and treatments received and to define barriers to the implementation of the American College of Critical Care Medicine/Pediatric Advanced Life Support guidelines in a pediatric intensive care unit in a developing country. Retrospective chart review and prospective analysis of septic shock treatment in a pediatric intensive care unit of a tertiary care teaching hospital. Ninety patients with severe sepsis or septic shock admitted between July 2002 and June 2003 were included in this study. Of the 90 patients, 83% had septic shock and 17% had severe sepsis; 80 patients had preexisting severe chronic diseases. Patients with septic shock who received less than a 20-mL/kg dose of resuscitation fluid in the first hour of treatment had a mortality rate of 73%, whereas patients who received more than a 40-mL/kg dose in the first hour of treatment had a mortality rate of 33% (P < 0.05). Patients treated less than 30 minutes after diagnosis of severe sepsis and septic shock had a significantly lower mortality rate (40%) than patients treated more than 60 minutes after diagnosis (P < 0.05). Controlling for the risk of mortality, early fluid resuscitation was associated with a 3-fold reduction in the odds of death (odds ratio, 0.33; 95% confidence interval, 0.13-0.85). The most important barriers to achieve adequate severe sepsis and septic shock treatment were lack of adequate vascular access, lack of recognition of early shock, shortage of health care providers, and nonuse of goals and treatment protocols. The mortality rate was higher for children older than 2 years, for those who received less than 40 mL/kg in the first hour, and for those whose treatment was not initiated in the first 30 minutes after the diagnosis of septic shock. The acknowledgment of existing barriers to a timely fluid administration and the establishment of objectives to overcome these barriers may lead to a more successful implementation of the American College of Critical Care Medicine guidelines and reduced mortality rates for children with septic shock in the developing world.
OBJETIVO: Analisar os indicadores de mortalidade para doenças cardiovasculares em São José do Rio... more OBJETIVO: Analisar os indicadores de mortalidade para doenças cardiovasculares em São José do Rio Preto, no estado de São Paulo e no Brasil e avaliar os coeficientes de mortalidade segundo níveis socioeconômicos da população do município. MÉTODOS: Utilizaram-se informações sobre mortalidade por doenças cardiovasculares e de população do Sistema de Informações de Mortalidade e do Departamento de Informação e Informática do Sistema Único de Saúde. Calcularam-se coeficientes padronizados de mortalidade e mortalidade proporcional por doenças cardiovasculares. Gerou-se mapa temático dos setores censitários da área urbana do município agrupados segundo níveis socioeconômicos, apresentado com os respectivos coeficientes. RESULTADOS: Os coeficientes de mortalidade para o município, o estado e o país decresceram de 1980 a 2002. Em 2003, o coeficiente do município foi de 195,9 óbitos por 100.000 habitantes, a mortalidade proporcional foi de 31,3% e as três principais causas de morte foram a doença cerebrovascular, o infarto e a doença hipertensiva. O coeficiente de mortalidade da população correspondente ao grupo de setores censitários com o pior nível socioeconômico foi 40% superior ao com o melhor nível. CONCLUSÃO: O coeficiente de mortalidade por doenças cardiovasculares decresceu nas três áreas geográficas analisadas. Do total de óbitos ocorridos em São José do Rio Preto em 2003, aproximadamente um terço foi por este grupo de doenças. A área com nível socioeconômico menos favorecido apresentou o maior coeficiente de mortalidade.
The mechanisms by which macromolecules are transported through the cell wall of fungi are not kno... more The mechanisms by which macromolecules are transported through the cell wall of fungi are not known. A central question in the biology of Cryptococcus neoformans, the causative agent of cryptococcosis, is the mechanism by which capsular polysaccharide synthesized inside the cell is exported to the extracellular environment for capsule assembly and release. We demonstrate that C. neoformans produces extracellular vesicles during in vitro growth and animal infection. Vesicular compartments, which are transferred to the extracellular space by cell wall passage, contain glucuronoxylomannan (GXM), a component of the cryptococcal capsule,
Inulinase is an enzyme relevant to fructose production by enzymatic hydrolysis of inulin. This en... more Inulinase is an enzyme relevant to fructose production by enzymatic hydrolysis of inulin. This enzyme is also applied in the production of fructo-oligosaccharides that may be used as a new food functional ingredient. Commercial inulinase is currently obtained using inulin as substrate, which is a relatively expensive raw material. In Brazil, the production of this enzyme using residues of sugarcane and corn industry (sugarcane bagasse, molasses, and corn steep liquor) is economically attractive, owing to the high amount and low cost of such residues. In this context, the aim of this work was the assessment of inulinase production by solid state fermentation using by Kluyveromyces marxianus NRRL Y-7571. The solid medium consisted of sugar cane bagasse supplemented with molasses and corn steep liquor. The production of inulinase was carried out using experimental design technique. The effect of temperature, moisture, and supplements content were investigated. The enzymatic activity reached a maximum of 445 units of inulinase per gram of dry substrate.
This work reports the production of monoacylglycerols (MAGs) from olive oil in pressurized propan... more This work reports the production of monoacylglycerols (MAGs) from olive oil in pressurized propane as solvent medium. For this purpose a commercial immobilized lipase (Novozym 435) was employed as catalyst and sodium (bis-2-ethyl-hexyl) sulfosuccinate (Aerosol-OT or AOT) as surfactant. The experiments were conducted in the batch mode keeping constant the glycerol to oil molar ratio of 2:1, propane to substrates mass ratio of 4:1, enzyme concentration (by weight of substrates) at 10 wt%, and agitation of 600 rpm, varying the temperature, pressure, and AOT concentration. Results showed that lipase-catalyzed glycerolysis in compressed propane might be a potential route to conventional methods, as high contents of reaction products, MAG and DAG, were achieved at mild temperature and pressure conditions (30 • C and 30 bar) with a low solvent to substrates mass ratio (4:1) in short-reaction times (1 h).
The cheese whey is an abundant residue obtained during the cheese processing and its disposal in ... more The cheese whey is an abundant residue obtained during the cheese processing and its disposal in the environment causes several drawbacks. The bioconversion of this by-product in added-value products is an important alternative to overcome this environmental problem. In this work, the feasibility of using cheese whey as carbon source for xanthan gum production was investigated using two strains of Xanthomonas campestris. The cheese whey:sucrose ratio and the supplementation of the medium were investigated by a Central Composite Design (CCD) in order to improve the xanthan gum production. Maximum xanthan gum productions were observed after 72 h using cheese whey as sole carbon source, 0.1% (w/v) MgSO 4 Â 7H 2 O and 2.0% (w/v) of K 2 HPO 4 , yielding approximately 25 g L À1 . This value is quite higher than some results presented in the literature using glucose as substrate. Although the production was similar for the two strains, chemical composition and ionic strength presented several differences in chemical characteristics between the polysaccharides produced.
Current studies about lipase production by solid-state fermentation involve the use of agro-indus... more Current studies about lipase production by solid-state fermentation involve the use of agro-industrial residues towards developing cost-effective systems directed to large-scale commercialization of enzyme-catalyzed processes. In this work, lipase production and partial characterization of the crude enzymatic extracts obtained by Penicillium verrucosum using soybean bran as substrate was investigated. Different inductors were evaluated and the results showed that there is no influence of this variable on the lipase production, while temperature and initial moisture were the main factors that affected enzyme production. The optimized cultivation temperature (27.5 °C) and initial moisture of substrate (55%) were determined using the response surface methodology. Kinetics of lipase production was followed at the optimized growth conditions. Optimum lipase yield was 40 U/g of dry bran. The crude enzymatic extract showed optimal activity in the range from 30 to 45 °C and in pH 7.0.
This review paper provides an overview regarding the main aspects of microbial lipases production... more This review paper provides an overview regarding the main aspects of microbial lipases production. The most important microbial lipase-producing strains for submerged and solid-state fermentations are reviewed as well as the main substrates, including the use of agroindustrial residues. Current process techniques (batch, repeated-batch, fed-batch, and continuous mode) are discussed and the main bioreactors configurations are also presented. Furthermore, the present review paper shows a general overview about the development of mathematical models applied to lipase production. Finally, some future perspectives on lipase production are discussed with special emphasis on lipase engineering and the use of mathematical models as a useful tool for process improvement and control.
The production of lipases by Penicillium simplicissimum using solid-state fermentation and soy ca... more The production of lipases by Penicillium simplicissimum using solid-state fermentation and soy cake as substrate was investigated. The effects of temperature, cake moisture, and carbon supplementation on lipase production were studied using a two-level experimental plan. Moisture, pH, and lipase activity were followed during fermentation. Statistical analysis of the results was performed to evaluate the effect of the studied variables on the maximum lipase activity. Incubation temperature was the variable that most affected enzyme activity, showing a negative effect. Moisture and carbon supplementation presented a positive effect on activity. It was possible to obtain lipase activity as high as 21 U/g of dry cake in the studied range of process variables.
This work investigates the production of fatty acid ethyl esters (FAEE) from soybean oil in compr... more This work investigates the production of fatty acid ethyl esters (FAEE) from soybean oil in compressed propane using Novozym 435 as catalyst. The experiments were performed in a batch reactor following the kinetics of the enzyme-catalyzed reaction in the temperature range of 35-65 • C, from 50 to 150 bar, enzyme concentration of 1-20 wt%, oil to ethanol molar ratio of 1:3-1:15 and solvent to substrates mass ratio of 1:1-4:1. Results showed that lipase-catalyzed alcoholysis in propane might be a potential alternative to conventional techniques for biodiesel production as complete conversions were obtained at mild temperature and pressure conditions, 65 • C and 50 bar, for an enzyme concentration of 5 wt% in 6 h of reaction.
This work investigates the influence of temperature, pressure, exposure times and depressurizatio... more This work investigates the influence of temperature, pressure, exposure times and depressurization rate on the activity of two commercial immobilized lipases submitted to compressed carbon dioxide, propane and n-butane. A high-pressure cell was employed in the experiments, varying the temperature from 35 to 75 • C, in the pressure range of 10-280 bar, exposure times from 1 to 6 h and adopting distinct decompression rates. Results showed that activity losses were verified for Lipozyme IM in all compressed solvents, markedly in carbon dioxide. For Novozym 435, treatment in carbon dioxide though in less extent also led to activity losses, while the use of propane and n-butane promoted enhancements of the enzyme activity. In general, within the range studied, temperature and exposure times affected positively enzyme activity while the decompression rates did not demonstrate to be a relevant variable. Additionally, an exploratory study was conducted to investigate the effect of compression/expansion cycles on enzyme activity in all solvents. Thermogravimetric analyses show that the thermal profiles of Novozym 435 treated in n-butane and in carbon dioxide are similar to the untreated enzyme. Scanning electron micrographs of Novozym 435 illustrate that the material submitted to carbon dioxide presented morphological alterations when compared to the untreated enzyme.
Recently, the use of supercritical CO 2 (SCCO 2 ) as a solvent in enzyme-catalyzed reactions has ... more Recently, the use of supercritical CO 2 (SCCO 2 ) as a solvent in enzyme-catalyzed reactions has been a matter of considerable research because of its favorable transport properties that can accelerate mass-transfer-limited enzymatic reactions. Further, biocatalysts, especially lipases, have substrate specificity and catalyze the syntheses of esters from a variety of acids and alcohols in SCCO 2 . Fatty acid esters obtained from alcoholysis of vegetable oils have many applications, such as antifriction agents, food preservatives, and emulsifiers. However, despite the industrial importance of the products obtained from alcoholysis of vegetable oils, conversions of such reactions in SCCO 2 have hardly been reported in the literature. Hence, the main objective of this work is to study the ethanolysis of palm kernel oil in SCCO 2 as catalyzed by two commercial lipases. The experiments were performed in a reactor vessel in the temperature range of 40-70°C and from 60 to 200 bar using a water concentration of 0-10 wt % and oil/ethanol molar ratios from 1:3 to 1:10. The initial reaction rate was found to be a function of both pressure and the oil/ethanol molar ratio. A simple model, capable of representing the conversion-time relationship curve, is proposed.
This work investigated the influence of temperature, pressure, exposure times and depressurizatio... more This work investigated the influence of temperature, pressure, exposure times and depressurization rate on the activity of a non-commercial immobilized lipase from Yarrowia lipolytica (YLL) submitted to compressed carbon dioxide, propane and n-butane. A high-pressure cell was employed in the experiments, in the pressure range of 10–280bar, varying the temperature from 35 to 75°C, exposure times from 1 to 6h,
... Also, to the best of our knowledge, there is no comprehensive study available comparing conve... more ... Also, to the best of our knowledge, there is no comprehensive study available comparing conventional and supercritical media for this reaction. ... For this purpose, a Taguchi experimentaldesign with two levels and four variables was adopted for each system to allow the ...
This article reports experimental data on the production of fatty acid ethyl esters from refined ... more This article reports experimental data on the production of fatty acid ethyl esters from refined and degummed soybean oil and castor oil using NaOH as catalyst. The variables investigated were temperature (30–70°C), reaction time (1–3 h), catalyst concentration (0.5–1.5 w/wt%), and oil-to-ethanol molar ratio (1:3–1:9). The effects of process variables on the reaction conversion as well as the optimum experimental conditions are presented. The results show that conversions >95% were achieved for all systems investigated. In general, an increase in reaction temperature, reaction time, and in oil-to-ethanol molar ratio led to an enhancement in reaction conversion, whereas an opposite trend was verified with respect to catalyst concentration.
This work investigates the continuous production of fatty acid ethyl esters from soybean oil in c... more This work investigates the continuous production of fatty acid ethyl esters from soybean oil in compressed fluids, namely carbon dioxide, propane and n-butane, using immobilized Novozym 435 as catalyst. The experiments were performed in a packed-bed bioreactor evaluating the effects of temperature in the range of 30-70°C, from 50 to 150 bar, oil to ethanol molar ratio of 1:6-1:18 and solvent to substrates mass ratio of 4:1-10:1. In contrast to the use of carbon dioxide and n-butane, results showed that lipasecatalyzed alcoholysis in a continuous tubular reactor in compressed propane might be a potential route to biodiesel production as high reaction conversions were achieved at mild temperature (70°C) and pressure (60 bar) conditions in short reaction times.
The objective of this work was to assess the influence of compressed CO 2 on the specific activit... more The objective of this work was to assess the influence of compressed CO 2 on the specific activity of peroxidase (POD) from radish (Raphanus sativus L.). The protein concentrate, in phosphate buffer, was obtained through the precipitation of proteins with (NH 4 ) 2 SO 4 . The peroxidase activity was determined using guaiacol as substrate. A semi-factorial experimental design was adopted to evaluate the effects of temperature (30-50 • C), exposure time (1-6 h), carbon dioxide density (ρ R = 0.6-1.8, resulting in pressures from 70.5 to 254.4 bar), and depressurization rate (10-200 kg/m 3 /min) on the peroxidase activity. Samples of lyophilized proteic concentrate were also submitted to high pressure and the effect of water content on the enzymatic activity in compressed CO 2 was studied. The water content in lyophilized samples was determined by thermogravimetric analysis. The results showed that the treatment of the enzymatic concentrate with CO 2 at high pressure could be a promising route to increase the POD activity.
The main objective of this work was to investigate the biotransformations of (−)α-pinene, (−)β-pi... more The main objective of this work was to investigate the biotransformations of (−)α-pinene, (−)β-pinene, and (+) limonene by Aspergillus niger ATCC 9642. The culture conditions involved—concentration of cosolvent (EtOH), substrate applied, and sequential addition of substrates—were investigated. Adaptation of the precultures with small amounts of substrate was also studied. The experiments were performed in conical flasks with liquid cultures. This strain of A. niger was able to convert only (−)β-pinene into α-terpineol. An optimum conversion of (−)β-pinene into α-terpineol of about 4% was obtained when the substrate was applied as a diluted solution in EtOH and sequential addition of substrate was used.
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Papers by debora oliveira