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Inês Conceição Roberto - One of the best experts on this subject based on the ideXlab platform.
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Inhibitory action of toxic compounds present in lignocellulosic hydrolysates on xylose to xylitol bioconversion by Candida Guilliermondii.
Journal of Industrial Microbiology & Biotechnology, 2010Co-Authors: Rogério S. Pereira, Solange I. Mussatto, Inês Conceição RobertoAbstract:The inhibitory action of acetic acid, ferulic acid, and syringaldehyde on metabolism of Candida Guilliermondii yeast during xylose to xylitol bioconversion was evaluated. Assays were performed in buffered and nonbuffered semidefined medium containing xylose as main sugar (80.0 g/l), supplemented or not with acetic acid (0.8–2.6 g/l), ferulic acid (0.2–0.6 g/l), and/or syringaldehyde (0.3–0.8 g/l), according to a 23 full factorial design. Since only individual effects of the variables were observed, assays were performed in a next step in semidefined medium containing different concentrations of each toxic compound individually, for better understanding of their maximum concentration that can be present in the fermentation medium without affecting yeast metabolism. It was concluded that acetic acid, ferulic acid, and syringaldehyde are compounds that may affect Candida Guilliermondii metabolism (mainly cell growth) during bioconversion of xylose to xylitol. Such results are of interest and reveal that complete removal of toxic compounds from the fermentation medium is not necessary to obtain efficient conversion of xylose to xylitol by Candida Guilliermondii. Fermentation in buffered medium was also considered as an alternative to overcome the inhibition caused by these toxic compounds, mainly by acetic acid.
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optimization of glucose 6 phosphate dehydrogenase releasing from Candida Guilliermondii by disruption with glass beads
Enzyme and Microbial Technology, 2006Co-Authors: Daniela De Borba Gurpilhares, Adalberto Pessoa, Francislene Andreia Hasmann, Inês Conceição RobertoAbstract:Abstract The release of glucose-6-phosphate dehydrogenase (G6PD) from Candida Guilliermondii, grown on rice straw hydrolysate, by vortex agitation with glass beads was studied. The effects of cell suspension concentration and disruption time on volumetric activity, total protein and specific activity were evaluated from a 22 full-factorial central composite design. By using the response surface methodology, a second-order model was proposed to represent enzyme specific activity as a function of disruption time (X1) and cell suspension concentration (X2). Under optimum conditions (X1 = 5 min and X2 = 11.5 g l−1 the model predicted a G6PD specific activity of 0.88 U mg−1.
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Study of xylitol production by Candida Guilliermondii on a bench bioreactor
Journal of Food Engineering, 2006Co-Authors: Carla J. S. M. Silva, Solange I. Mussatto, Inês Conceição RobertoAbstract:Abstract The kinetic behaviour of the yeast Candida Guilliermondii FTI 20037 was evaluated on a bench bioreactor using rice straw hydrolysate as a substrate. The maximum xylitol concentration (45.4 g l −1 ) was attained after 45 h of fermentation, which corresponded to a xylitol volumetric productivity of 1.01 g l −1 h −1 . This value was improved in about 90% when compared to the results attained with aerated flasks (0.54 g l −1 h −1 ). The kinetic results obtained in the present work reinforce the idea that rice straw hydrolysate constitutes an effective xylose source for xylitol production.
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kinetic behavior of Candida Guilliermondii yeast during xylitol production from highly concentrated hydrolysate
Process Biochemistry, 2004Co-Authors: Solange I. Mussatto, Inês Conceição RobertoAbstract:Abstract Rice straw hemicellulosic hydrolysate containing a high xylose concentration was used as fermentation medium to evaluate the kinetic behavior of Candida Guilliermondii yeast (FTI 20037) during the bioconversion of xylose into xylitol. Assays were conducted first with detoxified and non-detoxified (raw) hydrolysates and semi-synthetic medium in agitated flasks, and second with detoxified hydrolysate in a stirred-tank bioreactor at a given oxygen transfer rate. The results for the agitated flasks showed that in detoxified hydrolysate the xylose-to-xylitol bioconversion by the yeast was as effective as in synthetic medium and 47% higher than in raw hydrolysate. In the stirred-tank bioreactor, the kinetic behavior of the yeast in detoxified hydrolysate was slower, resulting in smaller values of fermentative parameters, probably due to unsuitability of the oxygen transfer rate employed ( K L a =22 h −1 ).
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Liquid-liquid extraction of xylitol dehydrogenase from Candida Guilliermondii homogenate by reversed micelles.
Journal of Chromatography B, 2004Co-Authors: Ely Vieira Cortez, Maria Das Graças De Almeida Felipe, Adalberto Pessoa, Inês Conceição Roberto, Michele VitoloAbstract:The intracellular enzyme xylitol dehydrogenase (XD, EC 1.1.1.9) from Candida Guilliermondii, grown in sugarcane bagasse hydrolysate, was separated by reversed micelles of BDBAC [N-benzyl-N-dodecyl-N-bis (2-hydroxyethyl) ammonium chloride] cationic surfactant. An experimental design was employed to evaluate the influence of the following factors on the enzyme separation: temperature, co-solvent concentration and surfactant concentration. The results showed that just the temperature did not show significant effect on XD recovery. A model was used to represent the activity recovery and fit the experimental data. Under optimized conditions, the recovery of total activity was about 121%, and the purity increased 2.3-fold.
S. S. Silva - One of the best experts on this subject based on the ideXlab platform.
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improvement of biotechnological xylitol production by glucose during cultive of Candida Guilliermondii in sugarcane bagasse hydrolysate
Brazilian Archives of Biology and Technology, 2007Co-Authors: Debora Danielle Virginio Da Silva, Ismael M. Mancilha, S. S. Silva, Maria Das Graças De Almeida FelipeAbstract:The effect of glucose on xylose-to-xylitol bioconversion by Candida Guilliermondii was examined by adding it to sugarcane bagasse hydrolysate medium to obtain different glucose:xylose ratios (1:25, 1:12, 1:5 and 1:2.5). Under experimental conditions, increasing glucose:xylose ratio improved the assimilation of the xylose present in the hydrolysate by yeast, resulting in biomass increase, and in the formation of xylitol and glycerol/ethanol by-products. Maximum values of xylitol yield (0.59 g g-1) and volumetric productivity (0.53 g l-1.h-1) were obtained with glucose:xylose ratio of 1:5, resulting in the higher conversion efficiency (64.3%).
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metabolic behavior of immobilized Candida Guilliermondii cells during batch xylitol production from sugarcane bagasse acid hydrolyzate
Biotechnology and Bioengineering, 2002Co-Authors: Walter Carvalho, S. S. Silva, Attilio Converti, Michele VitoloAbstract:Candida Guilliermondii cells, immobilized in Ca-alginate beads, were used for batch xylitol production from concentrated sugarcane bagasse hydrolyzate. Maximum xylitol concentration (20.6 g/L), volumetric productivity (0.43 g/L. h), and yield (0.47 g/g) obtained after 48 h of fermentation were higher than similar immobilized-cell systems but lower than free-cell cultivation systems. Substrates, products, and biomass concentrations were used in material balances to study the ways in which the different carbon sources were utilized by the yeast cells under microaerobic conditions. The fraction of xylose consumed to produce xylitol reached a maximum value (0.70) after glucose and oxygen depletion while alternative metabolic routes were favored by sub-optimal conditions.
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Mixed inhibitions by methanol, furfural and acetic acid on xylitol production by Candida Guilliermondii
Biotechnology Letters, 2000Co-Authors: Attilio Converti, Patrizia Perego, Paolo Torre, S. S. SilvaAbstract:Xylose production by Candida Guilliermondii FTI 20037 was carried out in a synthetic medium in the presence of 0–100 g methanol l−1, 0–0.7 g furfural l−1 or 0–1.3 g acetic acid l−1. Kinetic results show a mixed inhibition mechanism in all three cases. Maximum specific productivity and saturation constant for product formation were, in the absence of inhibition, 3.6 gP gX−1 h−1 and 232 gS l−1, respectively, while the inhibition constants, Ki and Ki′, were 17 and 50 g methanol l−1, 0.62 and 7.0 g furfural l−1, 0.69 and 3.5 g acetic acid l−1, which suggests the following order of inhibition: furfural > acetic acid > methanol.
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Xylose Reductase Production oy Candida Guilliermondii
Biotechnology for Fuels and Chemicals, 1998Co-Authors: S. M. A. Rosa, M. Vltolo, M. G. A. Felipe, S. S. SilvaAbstract:The effect of pH, time of fermentation, and xylose and glucose concentration on xylitol production, cell growth, xylose reductase (XR), and xylitol dehydrogenase (XD) activities of Candida Guilliermondii FTI 20037 were determined. For attaining XR and XD activities of 129-2190 U/mg of protein and 24-917 U/mg of protein, respectively, the cited parameters could vary as follows: initial pH: 3.0-5.0; xylose: 15-60 g/L; glucose: 0-5 g/L; and fermentation time: 12-24 h. Moreover, the high XR and XD activities occurred when the xylitol production by the yeast was less than 19.0 g/L.
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Adaptation and reutilization of Candida Guilliermondii cells for xylitol production in bagasse hydrolysate.
Journal of Basic Microbiology, 1998Co-Authors: Luciane Sene, Michele Vitolo, S. S. Silva, Maria Das Graças De Almeida Felipe, Ismael M. MancilhaAbstract:The xylitol productivity increased by about 15% with the use of cells of Candida Guilliermondii FTI 20037 previously recycled through four consecutive batch cultures and adapted to the sugar cane bagasse hemicellulosic hydrolysate. Furthermore, the more concentrated the hydrolysate, the more necessary was the adaptation of the cells, owing to the presence of toxic substances at high concentration which inhibited the xylose-xylitol conversion by the yeast.
Maria Das Graças De Almeida Felipe - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of sorghum straw hemicellulosic hydrolysate for biotechnological production of xylitol by Candida Guilliermondii
Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology], 2011Co-Authors: Luciane Sene, Priscila Vaz De Arruda, S.m.m Oliveira, Maria Das Graças De Almeida FelipeAbstract:A preliminary study on xylitol production by Candida Guilliermondii in sorghum straw hemicellulosic hydrolysate was performed. Hydrolysate had high xylose content and inhibitors concentrations did not exceed the commonly found values in other hemicellulosic hydrolysates. The highest xylitol yield (0.44 g/g) and productivity (0.19 g/Lh) were verified after 72 hours.
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Role of Glycerol Addition on Xylose-to-Xylitol Bioconversion by Candida Guilliermondii
Current Microbiology, 2008Co-Authors: Priscila Vaz De Arruda, Maria Das Graças De Almeida FelipeAbstract:The effect of glycerol on xylose-to-xylitol bioconversion by Candida Guilliermondii was evaluated by its addition (0.7 and 6.5 g/l) to semidefined media (xylose as a substrate). The glycerol concentrations were chosen based on the amounts produced during previous studies on xylitol production by C. Guilliermondii. Medium without glycerol addition (control) and medium containing glycerol (53 g/l) in substitution to xylose were also evaluated. According to the results, the addition of 0.7 g/l glycerol to the fermentation medium favored not only the yield (Y P/S = 0.78 g/g) but also the xylitol productivity (Q P = 1.13 g/l/h). During the xylose-to-xylitol bioconversion, the formation of byproducts (glycerol and ethanol) was observed for all conditions employed. In relation to the cellular growth, glycerol as the only carbon source for C. Guilliermondii was better than xylose or xylose and glycerol mixtures, resulting in a maximum cellular concentration (5.34 g/l).
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improvement of biotechnological xylitol production by glucose during cultive of Candida Guilliermondii in sugarcane bagasse hydrolysate
Brazilian Archives of Biology and Technology, 2007Co-Authors: Debora Danielle Virginio Da Silva, Ismael M. Mancilha, S. S. Silva, Maria Das Graças De Almeida FelipeAbstract:The effect of glucose on xylose-to-xylitol bioconversion by Candida Guilliermondii was examined by adding it to sugarcane bagasse hydrolysate medium to obtain different glucose:xylose ratios (1:25, 1:12, 1:5 and 1:2.5). Under experimental conditions, increasing glucose:xylose ratio improved the assimilation of the xylose present in the hydrolysate by yeast, resulting in biomass increase, and in the formation of xylitol and glycerol/ethanol by-products. Maximum values of xylitol yield (0.59 g g-1) and volumetric productivity (0.53 g l-1.h-1) were obtained with glucose:xylose ratio of 1:5, resulting in the higher conversion efficiency (64.3%).
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Liquid-liquid extraction of xylitol dehydrogenase from Candida Guilliermondii homogenate by reversed micelles.
Journal of Chromatography B, 2004Co-Authors: Ely Vieira Cortez, Maria Das Graças De Almeida Felipe, Adalberto Pessoa, Inês Conceição Roberto, Michele VitoloAbstract:The intracellular enzyme xylitol dehydrogenase (XD, EC 1.1.1.9) from Candida Guilliermondii, grown in sugarcane bagasse hydrolysate, was separated by reversed micelles of BDBAC [N-benzyl-N-dodecyl-N-bis (2-hydroxyethyl) ammonium chloride] cationic surfactant. An experimental design was employed to evaluate the influence of the following factors on the enzyme separation: temperature, co-solvent concentration and surfactant concentration. The results showed that just the temperature did not show significant effect on XD recovery. A model was used to represent the activity recovery and fit the experimental data. Under optimized conditions, the recovery of total activity was about 121%, and the purity increased 2.3-fold.
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batch xylitol production from wheat straw hemicellulosic hydrolysate using Candida Guilliermondii in a stirred tank reactor
Biotechnology Letters, 2003Co-Authors: Larissa Canilha, Maria Das Graças De Almeida Felipe, Joao Almeida B E Silva, Walter CarvalhoAbstract:Batch production of xylitol from the hydrolysate of wheat straw hemicellulose using Candida Guilliermondii was carried out in a stirred tank reactor (agitation speed of 300 rpm, aeration rate of 0.6 vvm and initial cell concentration of 0.5 g l−1). After 54 h, xylitol production from 30.5 g xylose l−1 reached 27.5 g l−1, resulting in a xylose-to-xylitol bioconversion yield of 0.9 g g−1 and a productivity of 0.5 g l−1 h−1.
Solange I. Mussatto - One of the best experts on this subject based on the ideXlab platform.
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xylitol production by debaryomyces hansenii and Candida Guilliermondii from rapeseed straw hemicellulosic hydrolysate
Bioresource Technology, 2018Co-Authors: Juan Carlos Lopezlinares, Inmaculada Romero, Cristobal Cara, Eulogio Castro, Solange I. MussattoAbstract:This study evaluated the possibility of using rapeseed straw hemicellulosic hydrolysate as a fermentation medium for xylitol production. Two yeast strains, namely Debaryomyces hansenii and Candida Guilliermondii, were used for this bioconversion process and their performance to convert xylose into xylitol was compared. Additionally, different strategies were evaluated for the hydrolysate detoxification before its use as a fermentation medium. Assays in semi-defined media were also performed to verify the influence of hexose sugars on xylose metabolism by the yeasts. C. Guilliermondii exhibited higher tolerance to toxic compounds than D. hansenii. Not only the toxic compounds present in the hydrolysate affected the yeast's performance, but glucose also had a negative impact on their performance. It was not necessary to completely eliminate the toxic compounds to obtain an efficient conversion of xylose into xylitol, mainly by C. Guilliermondii (YP/S=0.55g/g and 0.45g/g for C. Guilliermondii and D. hansenii, respectively).
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Inhibitory action of toxic compounds present in lignocellulosic hydrolysates on xylose to xylitol bioconversion by Candida Guilliermondii.
Journal of Industrial Microbiology & Biotechnology, 2010Co-Authors: Rogério S. Pereira, Solange I. Mussatto, Inês Conceição RobertoAbstract:The inhibitory action of acetic acid, ferulic acid, and syringaldehyde on metabolism of Candida Guilliermondii yeast during xylose to xylitol bioconversion was evaluated. Assays were performed in buffered and nonbuffered semidefined medium containing xylose as main sugar (80.0 g/l), supplemented or not with acetic acid (0.8–2.6 g/l), ferulic acid (0.2–0.6 g/l), and/or syringaldehyde (0.3–0.8 g/l), according to a 23 full factorial design. Since only individual effects of the variables were observed, assays were performed in a next step in semidefined medium containing different concentrations of each toxic compound individually, for better understanding of their maximum concentration that can be present in the fermentation medium without affecting yeast metabolism. It was concluded that acetic acid, ferulic acid, and syringaldehyde are compounds that may affect Candida Guilliermondii metabolism (mainly cell growth) during bioconversion of xylose to xylitol. Such results are of interest and reveal that complete removal of toxic compounds from the fermentation medium is not necessary to obtain efficient conversion of xylose to xylitol by Candida Guilliermondii. Fermentation in buffered medium was also considered as an alternative to overcome the inhibition caused by these toxic compounds, mainly by acetic acid.
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Study of xylitol production by Candida Guilliermondii on a bench bioreactor
Journal of Food Engineering, 2006Co-Authors: Carla J. S. M. Silva, Solange I. Mussatto, Inês Conceição RobertoAbstract:Abstract The kinetic behaviour of the yeast Candida Guilliermondii FTI 20037 was evaluated on a bench bioreactor using rice straw hydrolysate as a substrate. The maximum xylitol concentration (45.4 g l −1 ) was attained after 45 h of fermentation, which corresponded to a xylitol volumetric productivity of 1.01 g l −1 h −1 . This value was improved in about 90% when compared to the results attained with aerated flasks (0.54 g l −1 h −1 ). The kinetic results obtained in the present work reinforce the idea that rice straw hydrolysate constitutes an effective xylose source for xylitol production.
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kinetic behavior of Candida Guilliermondii yeast during xylitol production from highly concentrated hydrolysate
Process Biochemistry, 2004Co-Authors: Solange I. Mussatto, Inês Conceição RobertoAbstract:Abstract Rice straw hemicellulosic hydrolysate containing a high xylose concentration was used as fermentation medium to evaluate the kinetic behavior of Candida Guilliermondii yeast (FTI 20037) during the bioconversion of xylose into xylitol. Assays were conducted first with detoxified and non-detoxified (raw) hydrolysates and semi-synthetic medium in agitated flasks, and second with detoxified hydrolysate in a stirred-tank bioreactor at a given oxygen transfer rate. The results for the agitated flasks showed that in detoxified hydrolysate the xylose-to-xylitol bioconversion by the yeast was as effective as in synthetic medium and 47% higher than in raw hydrolysate. In the stirred-tank bioreactor, the kinetic behavior of the yeast in detoxified hydrolysate was slower, resulting in smaller values of fermentative parameters, probably due to unsuitability of the oxygen transfer rate employed ( K L a =22 h −1 ).
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Hydrolysate detoxification with activated charcoal for xylitol production by Candida Guilliermondii
Biotechnology Letters, 2001Co-Authors: Solange I. Mussatto, Inês Conceição RobertoAbstract:A detoxification method using activated charcoal with concentrated rice straw hemicellulosic hydrolysate improved the conversion of xylose to xylitol by the yeast Candida Guilliermondii by 22%. This was achieved when the hydrolysate:charcoal ratio was 40 g g−1, resulting in removal of 27% of phenolic compounds. Under this condition, the xylitol yield factor (0.72 g g−1) and volumetric productivity (0.61 g l−1 h−1) were close to those attained in a semi-defined medium simulating hydrolysate sugars.
Michele Vitolo - One of the best experts on this subject based on the ideXlab platform.
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Liquid-liquid extraction of xylitol dehydrogenase from Candida Guilliermondii homogenate by reversed micelles.
Journal of Chromatography B, 2004Co-Authors: Ely Vieira Cortez, Maria Das Graças De Almeida Felipe, Adalberto Pessoa, Inês Conceição Roberto, Michele VitoloAbstract:The intracellular enzyme xylitol dehydrogenase (XD, EC 1.1.1.9) from Candida Guilliermondii, grown in sugarcane bagasse hydrolysate, was separated by reversed micelles of BDBAC [N-benzyl-N-dodecyl-N-bis (2-hydroxyethyl) ammonium chloride] cationic surfactant. An experimental design was employed to evaluate the influence of the following factors on the enzyme separation: temperature, co-solvent concentration and surfactant concentration. The results showed that just the temperature did not show significant effect on XD recovery. A model was used to represent the activity recovery and fit the experimental data. Under optimized conditions, the recovery of total activity was about 121%, and the purity increased 2.3-fold.
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metabolic behavior of immobilized Candida Guilliermondii cells during batch xylitol production from sugarcane bagasse acid hydrolyzate
Biotechnology and Bioengineering, 2002Co-Authors: Walter Carvalho, S. S. Silva, Attilio Converti, Michele VitoloAbstract:Candida Guilliermondii cells, immobilized in Ca-alginate beads, were used for batch xylitol production from concentrated sugarcane bagasse hydrolyzate. Maximum xylitol concentration (20.6 g/L), volumetric productivity (0.43 g/L. h), and yield (0.47 g/g) obtained after 48 h of fermentation were higher than similar immobilized-cell systems but lower than free-cell cultivation systems. Substrates, products, and biomass concentrations were used in material balances to study the ways in which the different carbon sources were utilized by the yeast cells under microaerobic conditions. The fraction of xylose consumed to produce xylitol reached a maximum value (0.70) after glucose and oxygen depletion while alternative metabolic routes were favored by sub-optimal conditions.
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Adaptation and reutilization of Candida Guilliermondii cells for xylitol production in bagasse hydrolysate.
Journal of Basic Microbiology, 1998Co-Authors: Luciane Sene, Michele Vitolo, S. S. Silva, Maria Das Graças De Almeida Felipe, Ismael M. MancilhaAbstract:The xylitol productivity increased by about 15% with the use of cells of Candida Guilliermondii FTI 20037 previously recycled through four consecutive batch cultures and adapted to the sugar cane bagasse hemicellulosic hydrolysate. Furthermore, the more concentrated the hydrolysate, the more necessary was the adaptation of the cells, owing to the presence of toxic substances at high concentration which inhibited the xylose-xylitol conversion by the yeast.
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Environmental parameters affecting xylitol production from sugar cane bagasse hemicellulosic hydrolyzate by Candida Guilliermondii
Journal of Industrial Microbiology and Biotechnology, 1997Co-Authors: M. G. A. Felipe, Ismael M. Mancilha, Michele Vitolo, S. S. SilvaAbstract:The bioconversion of xylose to xylitol by Candida Guilliermondii FTI 20037 cultivated in sugar cane bagasse hemicellulosic hydrolyzate was influenced by cell inoculum level, age of inoculum and hydrolyzate concentration. The maximum xylitol productivity (0.75 g L−1 h−1) occurred in tests carried out with hydrolyzate containing 54.5 g L−1 of xylose, using 3.0 g L−1 of a 24-h-old inoculum. Xylitol productivity and cell concentration decreased with hydrolyzate containing 74.2 g L−1 of xylose.
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Xylose reductase and xylitol dehydrogenase activities of D‐xylose‐xylitol‐fermenting Candida Guilliermondii
Journal of Basic Microbiology, 1996Co-Authors: S. S. Silva, Michele Vitolo, Adalberto Pessoa, M. G. A. FelipeAbstract:The effect of the inoculum age and initial xylose concentration on the activities of xylose reductase (XR) and xylitol dehydrogenase (XD) of Candida Guilliermondii FTI 20037 were investigated. Under the experimental conditions used, the XR and XD activities were, respectively. NADPH and NAD or NADP dependent. The NADP/NADPH ratio for XR was not substantially influenced by the age of inoculum or the initial xylose concentration. The Km of XR (0.18 M) was about 4-folds smaller than the Km of XD NAD-dependent. A renewable xylose-xylitol conversion was obtained with 40 h aged inoculum of Candida Guilliermondii FTI 20037 grown in a medium containing an initial xylose concentration of 120g/l.
