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Research paper thumbnail of Microbial Enzyme Applications in Bioethanol Producing Biorefineries: Overview

Bioethanol Production from Food Crops, 2019

Abstract Biorefineries for bioethanol production have followed a steady evolution along with impr... more Abstract Biorefineries for bioethanol production have followed a steady evolution along with improvements related to enzymatic activity and hydrolysis technology. Whichever operation strategy is followed (separated hydrolysis and fermentation, simultaneous saccharification and fermentation, or consolidated bioprocessing), the enzymes that play a major role in this growing industry are amylases and cellulases, yet accessory enzymes have gained recent attention. This chapter reviews enzyme applications on bioethanol biorefineries, covering the basics of enzyme technology, its application on first- and second-generation biofuels and the recent insights on heterologous enzyme expression, tailoring enzymes, enzymes recycling, immobilization, and enzyme synergy.

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Research paper thumbnail of Physiological concentrations of short-chain fatty acids immediately suppress colonic epithelial permeability

British Journal of Nutrition, 2008

Colonic fermentation products, SCFA, have various effects on colonic functions. Here, we found th... more Colonic fermentation products, SCFA, have various effects on colonic functions. Here, we found that physiological concentrations of SCFA immediately promote epithelial barrier function in the large intestine. Solutions of mixed and individual SCFA were applied to the caecal walls mounted on Ussing-type chambers. Transepithelial electrical resistance (TER) increased rapidly and reached a peak 35 % higher than that in the control specimen within 10 min post application of the SCFA mixture (80 acetate, 40 propionate, 20 butyrate (mmol/l)). The Lucifer yellow permeability, a paracellular transport marker, was dose-dependently reduced by the mixed SCFA, acetate and propionate solutions. Inhibition of monocarboxylate transporter-1 did not influence the increase in TER with acetate; however, lowering the pH (from 7·5 to 5·5) clearly enhanced the effect of acetate. Non-metabolizable, bromo and chloro derivatives of SCFA also increased TER. These results suggest that passive diffusion of SCF...

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Research paper thumbnail of Production of cellulases and xylanases under catabolic repression conditions from mutant PR-22 of Cellulomonas flavigena

Journal of Industrial Microbiology & Biotechnology, 2010

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Research paper thumbnail of Production of Cellulase and Xylanase by Cellulomonas flavigena immobilized in Sodium Alginate in Bubble Column Reactors

Journal of Biotechnology, 2010

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Research paper thumbnail of Kinetic parameters of Lactobacillus plantarum and Saccharomyces boulardii growing in a beet molasses culture media

Revista Mexicana de Ingeniería Química, 2020

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Research paper thumbnail of Fermentation: Metabolism, Kinetic Models, and Bioprocessing

Current Topics in Biochemical Engineering [Working Title]

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Research paper thumbnail of Saccharification of cellulosic biomass: Regulation of cellulase and xylanase activities under catabolic repression conditions

Journal of Biotechnology, 2007

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Research paper thumbnail of Saccharification of cellulosic biomass: Regulation of cellulase and xylanase activities under catabolic repression conditions

Journal of Biotechnology, 2007

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Research paper thumbnail of The impact of particle size and initial solid loading on thermochemical pretreatment of wheat straw for improving sugar recovery

This work studies the effect of initial solid load (4-32 %; w/v, DS) and particle size (0.41-50 m... more This work studies the effect of initial solid load (4-32 %; w/v, DS) and particle size (0.41-50 mm) on monosaccharide yield of wheat straw subjected to dilute H(2)SO(4) (0.75 %, v/v) pretreatment and enzymatic saccharification. Response surface methodology (RSM) based on a full factorial design (FFD) was used for the statistical analysis of pretreatment and enzymatic hydrolysis. The highest xylose yield obtained during pretreatment (ca. 86 %; of theoretical) was achieved at 4 % (w/v, DS) and 25 mm. The solid fraction obtained from the first set of experiments was subjected to enzymatic hydrolysis at constant enzyme dosage (17 FPU/g); statistical analysis revealed that glucose yield was favored with solids pretreated at low initial solid loads and small particle sizes. Dynamic experiments showed that glucose yield did not increase after 48 h of enzymatic hydrolysis. Once established pretreatment conditions, experiments were carried out with several initial solid loading (4-24 %; w/v, DS) and enzyme dosages (5-50 FPU/g). Two straw sizes (0.41 and 50 mm) were used for verification purposes. The highest glucose yield (ca. 55 %; of theoretical) was achieved at 4 % (w/v, DS), 0.41 mm and 50 FPU/g. Statistical analysis of experiments showed that at low enzyme dosage, particle size had a remarkable effect over glucose yield and initial solid load was the main factor for glucose yield.

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Research paper thumbnail of Sequential pretreatment strategies under mild conditions for efficient enzymatic hydrolysis of wheat straw

Bioprocess and biosystems engineering, Jan 20, 2015

This work studies the sequential execution of dilute sulfuric acid (DAP) (0.1-0.75 %, v/v) and di... more This work studies the sequential execution of dilute sulfuric acid (DAP) (0.1-0.75 %, v/v) and dilute sodium hydroxide (AKP) (0.25-3 %, w/v) [i.e., DAP followed by AKP (DAP+AKP) and vice versa (AKP+DAP)] at low temperatures (<121 °C) and short reaction times (5-60 min) for maximizing sugar recovery in the enzymatic hydrolysis of wheat straw with low enzyme dosage. The pretreatment effectiveness was measured by the sum of the severity factors of both pretreatments and the saccharification yield achieved in the subsequent stage of enzymatic hydrolysis. Degradation compounds were quantified and mass balance calculations were carried out for each pretreatment sequence to verify the correct account of the input biomass and output products. Results show that sequential pretreatments (AKP+DAP and DAP+AKP) had a positive effect in enzyme accessibility thus improving monosaccharide yields compared to single DAP and AKP pretreatments. DAP+AKP achieved a high xylose yield (ca. 0.867 of theo...

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Research paper thumbnail of Production of Cellulase and Xylanase by Cellulomonas flavigena immobilized in Sodium Alginate in Bubble Column Reactors

Journal of Biotechnology, 2010

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Research paper thumbnail of The impact of particle size and initial solid loading on thermochemical pretreatment of wheat straw for improving sugar recovery

Bioprocess and Biosystems Engineering, 2014

This work studies the effect of initial solid load (4-32 %; w/v, DS) and particle size (0.41-50 m... more This work studies the effect of initial solid load (4-32 %; w/v, DS) and particle size (0.41-50 mm) on monosaccharide yield of wheat straw subjected to dilute H(2)SO(4) (0.75 %, v/v) pretreatment and enzymatic saccharification. Response surface methodology (RSM) based on a full factorial design (FFD) was used for the statistical analysis of pretreatment and enzymatic hydrolysis. The highest xylose yield obtained during pretreatment (ca. 86 %; of theoretical) was achieved at 4 % (w/v, DS) and 25 mm. The solid fraction obtained from the first set of experiments was subjected to enzymatic hydrolysis at constant enzyme dosage (17 FPU/g); statistical analysis revealed that glucose yield was favored with solids pretreated at low initial solid loads and small particle sizes. Dynamic experiments showed that glucose yield did not increase after 48 h of enzymatic hydrolysis. Once established pretreatment conditions, experiments were carried out with several initial solid loading (4-24 %; w/v, DS) and enzyme dosages (5-50 FPU/g). Two straw sizes (0.41 and 50 mm) were used for verification purposes. The highest glucose yield (ca. 55 %; of theoretical) was achieved at 4 % (w/v, DS), 0.41 mm and 50 FPU/g. Statistical analysis of experiments showed that at low enzyme dosage, particle size had a remarkable effect over glucose yield and initial solid load was the main factor for glucose yield.

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Research paper thumbnail of Production of cellulases and xylanases under catabolic repression conditions from mutant PR-22 of Cellulomonas flavigena

Journal of Industrial Microbiology & Biotechnology, 2011

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Research paper thumbnail of Microbial Enzyme Applications in Bioethanol Producing Biorefineries: Overview

Bioethanol Production from Food Crops, 2019

Abstract Biorefineries for bioethanol production have followed a steady evolution along with impr... more Abstract Biorefineries for bioethanol production have followed a steady evolution along with improvements related to enzymatic activity and hydrolysis technology. Whichever operation strategy is followed (separated hydrolysis and fermentation, simultaneous saccharification and fermentation, or consolidated bioprocessing), the enzymes that play a major role in this growing industry are amylases and cellulases, yet accessory enzymes have gained recent attention. This chapter reviews enzyme applications on bioethanol biorefineries, covering the basics of enzyme technology, its application on first- and second-generation biofuels and the recent insights on heterologous enzyme expression, tailoring enzymes, enzymes recycling, immobilization, and enzyme synergy.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Physiological concentrations of short-chain fatty acids immediately suppress colonic epithelial permeability

British Journal of Nutrition, 2008

Colonic fermentation products, SCFA, have various effects on colonic functions. Here, we found th... more Colonic fermentation products, SCFA, have various effects on colonic functions. Here, we found that physiological concentrations of SCFA immediately promote epithelial barrier function in the large intestine. Solutions of mixed and individual SCFA were applied to the caecal walls mounted on Ussing-type chambers. Transepithelial electrical resistance (TER) increased rapidly and reached a peak 35 % higher than that in the control specimen within 10 min post application of the SCFA mixture (80 acetate, 40 propionate, 20 butyrate (mmol/l)). The Lucifer yellow permeability, a paracellular transport marker, was dose-dependently reduced by the mixed SCFA, acetate and propionate solutions. Inhibition of monocarboxylate transporter-1 did not influence the increase in TER with acetate; however, lowering the pH (from 7·5 to 5·5) clearly enhanced the effect of acetate. Non-metabolizable, bromo and chloro derivatives of SCFA also increased TER. These results suggest that passive diffusion of SCF...

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Research paper thumbnail of Production of cellulases and xylanases under catabolic repression conditions from mutant PR-22 of Cellulomonas flavigena

Journal of Industrial Microbiology & Biotechnology, 2010

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Research paper thumbnail of Production of Cellulase and Xylanase by Cellulomonas flavigena immobilized in Sodium Alginate in Bubble Column Reactors

Journal of Biotechnology, 2010

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Research paper thumbnail of Kinetic parameters of Lactobacillus plantarum and Saccharomyces boulardii growing in a beet molasses culture media

Revista Mexicana de Ingeniería Química, 2020

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Fermentation: Metabolism, Kinetic Models, and Bioprocessing

Current Topics in Biochemical Engineering [Working Title]

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Research paper thumbnail of Saccharification of cellulosic biomass: Regulation of cellulase and xylanase activities under catabolic repression conditions

Journal of Biotechnology, 2007

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Saccharification of cellulosic biomass: Regulation of cellulase and xylanase activities under catabolic repression conditions

Journal of Biotechnology, 2007

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The impact of particle size and initial solid loading on thermochemical pretreatment of wheat straw for improving sugar recovery

This work studies the effect of initial solid load (4-32 %; w/v, DS) and particle size (0.41-50 m... more This work studies the effect of initial solid load (4-32 %; w/v, DS) and particle size (0.41-50 mm) on monosaccharide yield of wheat straw subjected to dilute H(2)SO(4) (0.75 %, v/v) pretreatment and enzymatic saccharification. Response surface methodology (RSM) based on a full factorial design (FFD) was used for the statistical analysis of pretreatment and enzymatic hydrolysis. The highest xylose yield obtained during pretreatment (ca. 86 %; of theoretical) was achieved at 4 % (w/v, DS) and 25 mm. The solid fraction obtained from the first set of experiments was subjected to enzymatic hydrolysis at constant enzyme dosage (17 FPU/g); statistical analysis revealed that glucose yield was favored with solids pretreated at low initial solid loads and small particle sizes. Dynamic experiments showed that glucose yield did not increase after 48 h of enzymatic hydrolysis. Once established pretreatment conditions, experiments were carried out with several initial solid loading (4-24 %; w/v, DS) and enzyme dosages (5-50 FPU/g). Two straw sizes (0.41 and 50 mm) were used for verification purposes. The highest glucose yield (ca. 55 %; of theoretical) was achieved at 4 % (w/v, DS), 0.41 mm and 50 FPU/g. Statistical analysis of experiments showed that at low enzyme dosage, particle size had a remarkable effect over glucose yield and initial solid load was the main factor for glucose yield.

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Research paper thumbnail of Sequential pretreatment strategies under mild conditions for efficient enzymatic hydrolysis of wheat straw

Bioprocess and biosystems engineering, Jan 20, 2015

This work studies the sequential execution of dilute sulfuric acid (DAP) (0.1-0.75 %, v/v) and di... more This work studies the sequential execution of dilute sulfuric acid (DAP) (0.1-0.75 %, v/v) and dilute sodium hydroxide (AKP) (0.25-3 %, w/v) [i.e., DAP followed by AKP (DAP+AKP) and vice versa (AKP+DAP)] at low temperatures (<121 °C) and short reaction times (5-60 min) for maximizing sugar recovery in the enzymatic hydrolysis of wheat straw with low enzyme dosage. The pretreatment effectiveness was measured by the sum of the severity factors of both pretreatments and the saccharification yield achieved in the subsequent stage of enzymatic hydrolysis. Degradation compounds were quantified and mass balance calculations were carried out for each pretreatment sequence to verify the correct account of the input biomass and output products. Results show that sequential pretreatments (AKP+DAP and DAP+AKP) had a positive effect in enzyme accessibility thus improving monosaccharide yields compared to single DAP and AKP pretreatments. DAP+AKP achieved a high xylose yield (ca. 0.867 of theo...

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Research paper thumbnail of Production of Cellulase and Xylanase by Cellulomonas flavigena immobilized in Sodium Alginate in Bubble Column Reactors

Journal of Biotechnology, 2010

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Research paper thumbnail of The impact of particle size and initial solid loading on thermochemical pretreatment of wheat straw for improving sugar recovery

Bioprocess and Biosystems Engineering, 2014

This work studies the effect of initial solid load (4-32 %; w/v, DS) and particle size (0.41-50 m... more This work studies the effect of initial solid load (4-32 %; w/v, DS) and particle size (0.41-50 mm) on monosaccharide yield of wheat straw subjected to dilute H(2)SO(4) (0.75 %, v/v) pretreatment and enzymatic saccharification. Response surface methodology (RSM) based on a full factorial design (FFD) was used for the statistical analysis of pretreatment and enzymatic hydrolysis. The highest xylose yield obtained during pretreatment (ca. 86 %; of theoretical) was achieved at 4 % (w/v, DS) and 25 mm. The solid fraction obtained from the first set of experiments was subjected to enzymatic hydrolysis at constant enzyme dosage (17 FPU/g); statistical analysis revealed that glucose yield was favored with solids pretreated at low initial solid loads and small particle sizes. Dynamic experiments showed that glucose yield did not increase after 48 h of enzymatic hydrolysis. Once established pretreatment conditions, experiments were carried out with several initial solid loading (4-24 %; w/v, DS) and enzyme dosages (5-50 FPU/g). Two straw sizes (0.41 and 50 mm) were used for verification purposes. The highest glucose yield (ca. 55 %; of theoretical) was achieved at 4 % (w/v, DS), 0.41 mm and 50 FPU/g. Statistical analysis of experiments showed that at low enzyme dosage, particle size had a remarkable effect over glucose yield and initial solid load was the main factor for glucose yield.

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Research paper thumbnail of Production of cellulases and xylanases under catabolic repression conditions from mutant PR-22 of Cellulomonas flavigena

Journal of Industrial Microbiology & Biotechnology, 2011

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