An approach to optimization of enzymatic hydrolysis from sugarcane bagasse based on organosolv pretreatment

BACKGROUND: The organosolv pretreatment followed by enzymatic hydrolysis of the pretreated material and subsequent fermentation of the hydrolysate produced, was the strategy used for ethanol production from sugarcane bagasse. The effect of different operational variables affecting the pretreatment (the catalyst type and its concentration, and the pretreatment time) and enzymatic hydrolysis stage (substrate concentration, cellulase loading, addition of xylanase and Tween 20, and the cellulase/β‐glucosidase ratio), were investigated. RESULTS: The best values of glucose concentration (28.8 g L^?1) and yield (25.1 g per 100 g dry matter) were obtained when the material was pretreated with 1.25% (w/w) H₂SO₄ for 60 min, and subsequently hydrolyzed using 10% (w/v) substrate concentration in a reaction medium supplemented with xylanase (300 UI g^?1) and Tween 20 (2.5% w/w). Fermentation of the broth obtained under these optimum conditions by Saccharomyces cerevisiae resulted in an ethanol yield of 92.8% based on the theoretical yield, after 24 h. CONCLUSION: Organosolv pretreatment of sugarcane bagasse under soft conditions, and subsequent enzymatic hydrolysis of the pretreated material with a cellulolytic system supplemented with xylanase and Tween 20, is a suitable procedure to obtain a glucose rich hydrolysate efficiently fermentable to ethanol by Sacharomyces cerevisiae yeasts. Copyright © 2010 Society of Chemical Industry     

Enzymatic hydrolysis of autohydrolyzed barley husks

BACKGROUND: Barley husks were subjected to non‐isothermal autohydrolysis of different severities, yielding a liquid phase rich in hemicellulose‐derived compounds and a solid phase, composed mainly of cellulose and lignin. This solid phase was subjected to enzymatic hydrolysis in order to assess the effects of severity on the susceptibility of substrates to enzymatic hydrolysis. The effects of the liquid to solid ratio (LSR, in the range 6 to 18 g g^?1) and cellulase to substrate ratio (CSR, in the range 3.3 to 8.2 FPU g^?1) on the enzymatic hydrolysis were assessed. RESULTS: Up to 25.8 g oligomers per 100 g raw material were present in liquors from the hydrothermal processing. Enzymatic hydrolysis of solid phases obtained under selected conditions (log Ro = 4.14, LSR = 6 g g^?1 and CSR = 5.8 FPU g^?1) yielded glucose concentrations up to 67 g L^?1 (corresponding to cellulose to glucose conversions close to 100%). CONCLUSION: It was shown that autohydrolysis is an effective method for improving the enzymatic susceptibility of barley husks. High cellulose conversions resulting in high glucose yields were achieved by enzymatic hydrolysis at low LSR and CSR. The liquid fraction obtained upon autohydrolysis contained large amounts of hemicellulose‐derived compounds. Copyright © 2010 Society of Chemical Industry     

High efficiency bioethanol production from OPEFB using pilot pretreatment reactor

BACKGROUND: Current ethanol production processes using crops such as corn and sugar cane are well established. However, the utilization of cheaper biomasses such as lignocellulose could make bioethanol more competitive with fossil fuels while avoiding the ethical concerns associated with using potential food resources. RESULTS: Oil palm empty fruit bunches (OPEFB), a lignocellulosic biomass, was pretreated using NaOH to produce bioethanol. The pretreatment and enzymatic hydrolysis conditions were evaluated by response surface methodology (RSM). The optimal conditions were found to be 127.64 °C, 22.08 min, and 2.89 mol L^?1 for temperature, reaction time, and NaOH concentration, respectively. Regarding enzymatic digestibility, 50 FPU g^?1 cellulose of cellulase was selected as the test concentration, resulting in a total glucose conversion rate (TGCR) of 86.37% using the Changhae Ethanol Multi Explosion (CHEMEX) facility. Fermentation of pretreated OPEFB using Saccharomyces cerevisiae resulted in an ethanol concentration of 48.54 g L^?1 at 20% (w/v) pretreated biomass loading, along with simultaneous saccharification and fermentation (SSF) processes. Overall, 410.48 g of ethanol were produced from 3 kg of raw OPEFB in a single run, using the CHEMEX_50 L reactor. CONCLUSION: The results presented here constitute a significant contribution to the production of bioethanol from OPEFB. Copyright © 2011 Society of Chemical Industry     

Enzymatic hydrolysis and fermentation of lime pretreated wheat straw to ethanol

BACKGROUND: The objective of this work is to develop an efficient pretreatment method that can help enzymes break down the complex carbohydrates present in wheat straw to sugars, and to then ferment of all these sugars to ethanol. RESULTS: The yield of sugars from wheat straw (8.6%, w/v) by lime pretreatment (100 mg g^?1 straw, 121 °C, 1 h) and enzymatic hydrolysis (45 °C, pH 5.0, 120 h) using a cocktail of three commercial enzyme preparations (cellulase, β‐glucosidase, and xylanase) at the dose level of 0.15 mL of each enzyme preparation g^?1 straw was 568 ± 13 mg g^?1 (82% yield). The concentration of ethanol from lime pretreated enzyme saccharified wheat straw (78 g) hydrolyzate by recombinant Escherichia coli strain FBR5 at pH 6.5 and 35 °C in 24 h was 22.5 ± 0.6 g L^?1 with a yield of 0.50 g g^?1 available sugars (0.29 g g^?1 straw). The ethanol concentration was 20.6 ± 0.4 g L^?1 with a yield of 0.26 g g^?1 straw in the case of simultaneous saccharification and fermentation by the E. coli strain at pH 6.0 and 35 °C in 72 h. CONCLUSION: The results are important in choosing a suitable pretreatment option for developing bioprocess technologies for conversion of wheat straw to fuel ethanol. Copyright © 2007 Society of Chemical Industry     

Experimental evaluation of alkaline treatment as a method for enhancing the enzymatic digestibility of autohydrolysed Acacia dealbata

BACKGROUND: Acacia dealbata wood samples were subjected to hydrothermal processing in aqueous media, yielding a liquid phase (containing xylooligosaccharides) and a solid phase, enriched in cellulose, which was treated with alkaline solutions to obtain solids with improved susceptibility towards enzymatic hydrolysis. The effects of the most influential variables involved in the alkaline processing (sodium hydroxide concentration, temperature and reaction time) on solid yield, solid composition and kinetic parameters involved in the modelling of the enzymatic hydrolysis were assessed using the response surface methodology (RSM). RESULTS: Analysis of the RSM equations allowed selection of operational conditions (temperature = 130 °C, sodium hydroxide concentration = 4.5%, time of alkaline processing = 3 h), leading to selective removal of non‐cellulosic components and to a solid substrate highly susceptible to enzymatic hydrolysis. Operating at an enzyme loading of 20 FPU (filter paper units) g^?1 autohydrolysed, extracted solids (denoted AES) with a liquor to solid ratio of 30 g liquor g^?1 AES, solutions containing 29.7 g glucose L^?1 (corresponding to a yield of 47.3 g glucose per 100 g solids from autohydrolysis) were obtained after 48 h. CONCLUSION: Samples of Acacia dealbata wood were processed by autohydrolysis, sodium hydroxide treatment and enzymatic hydrolysis, yielding xylooligomers and processed solids highly susceptible to the enzymatic hydrolysis. Copyright © 2009 Society of Chemical Industry     

Utilization of lignocellulosic waste for ethanol production : Enzymatic digestibility and fermentation of pretreated shea tree sawdust

Enzymatic hydrolysis and fermentation methods were evaluated on alkaline peroxide pretreated shea tree sawdust conversion to ethanol. Optimum pretreatment conditions of 120 °C reaction temperature, 30 min reaction time, and 20 mL L^?1 of water hydrogen peroxide concentration (1%(v/v)H₂O₂) solubilized 679 g kg^?1 of hemicellulose and 172 g kg^?1 of lignin. 617 g kg^?1 cellulose was retained in the solid fraction. The maximum yield of reducing sugar with optimized enzyme loadings by two enzyme preparations (cellulase and β-glucosidase) was 165 g kg^?1 of dry biomass. The ethanol yield was 7.35 g L^?1 after 72 h incubation period under the following conditions: 2% cellulose loading, enzyme concentration was 25 FPU (g cellulose)^?1 loading, yeast inoculums was 10% (v/v), 32 oC, and pH 4.8. The pretreatments gave information about the hindrances caused by lignin presence in lignocellulosic materials and that hemicelluloses are better hydrolyzed than lignin, thereby enhancing enzymatic digestibility of the sawdust material.     

Simultaneous saccharification and fermentation of pretreated Antigonum leptopus (Linn) leaves to ethanol

Simultaneous saccharification and fermentation (SSF) of alkaline hydrogen peroxide pretreated Antigonum leptopus (Linn) leaves to ethanol was optimized using cellulase from Trichoderma reesei QM‐9414 (Celluclast® from Novo) and Saccharomyces cerevisiae NRRL‐Y‐132 cells. Contrary to the saccharification optima (2.5% w/v substrate concentration, 50 °C, 4.5 pH, 40 FPU cellulase g⁻¹ substrate and 24 h reaction time), the SSF optima was found to be somewhat different (10% w/v substrate, 40 °C, 100 FPU cellulase g⁻¹ substrate and 72 h). Better ethanol yields were obtained with SSF compared with the traditional saccharification and subsequent fermentation (S&F) and when the cellulase was supplemented with β‐glucosidase. © 1999 Society of Chemical Industry     

Effects of dilute acid pretreatment on enzyme saccharification of wheat stubble

BACKGROUND: Prehydrolysis of wheat stubble using moderate temperatures and dilute acid strength is an effective means for solubilizing hemicellulose fractions and improving cellulose hydrolysis. Variation in prehydrolysis parameters (temperature, time, and acid strength) and enzymatic saccharification conditions were examined for conversion of wheat stubble into fermentable sugars. RESULTS: Elevating temperature and acid strength maximized sugar release in prehydrolysate liquors. The optimal conditions of 2.0% H₂SO₄/60 min/121 °C effectively solubilized 79% of the available hemicellulose. Production of inhibitory hydrolysis and degradation products such as acetic acid and levulinic acid, were detected at levels of 3.4 g L^?1 and 0.64 g L^?1, respectively. Sugar yields in prehydrolysate and saccharified liquors were found to increase with treatment severity. Temperature had the greatest impact on sugar release, followed by acid concentration and time. Optimizing prehydrolysis conditions at 1.0% H₂SO₄/90 min/121 °C, produced a 3.2‐fold improvement in cellulose hydrolysis with recoveries approaching 82%. The addition of β‐glucosidase and xylanase to the cellulase preparations assisted monomeric sugar release. CONCLUSION: Although treatment conditions for hemicellulose and cellulose hydrolysis differ, the study's findings suggest a good degree of overlap and process flexibility which should permit high recovery of pentose and hexose sugars. Copyright © 2011 Society of Chemical Industry     

Optimization of the enzymatic hydrolysis conditions of steam‐exploded wheat straw for maximum glucose and xylose recovery

BACKGROUND: The enzymatic hydrolysis of steam‐exploded wheat straw using commercial enzyme complexes has been studied. A cellulase enzyme complex (Accellerase 1500), along with specific xylanase complements (Accellerase‐XC and Accellerase‐XY) provided by Genencor, have been used to enhance glucose and xylose recovery. A systematic study with response surface methodology (RSM) was used to check the effect of the operating conditions: pH (4–5), temperature (50–60 °C) and enzyme/substrate ratio (0.1–0.5 mL g_cellulose^?1) on the enzymatic hydrolysis with Acellerase 1500 to maximize the sugar yield. Xylanases were used as complements to increase the release of xylose. RESULT: Statistical results from ANOVA analysis demonstrated that the enzymatic hydrolysis was clearly improved by temperature and enzyme/substrate ratio. The optimum conditions for higher glucose and xylose releases were obtained with the higher enzyme dosage ratio (0.5 mL g^?1_cellulose), 50 °C and pH 4. CONCLUSION: Model validation at optimum operating conditions showed good agreement between the experimental results and the predicted responses for a confidence level of 95%. The use of the xylanase complements, Accellerase‐XY (accessory xylanase enzyme complex) and Accellerase‐XC (accessory xylanase/cellulase enzyme complex), increases the conversion of hemicellulose. Accellerase‐XC supplementation was more effective, obtaining an increase in yields of glucose and xylose of 11.8% and 23.6%, respectively, using a dosage of 0.125 mL g^?1_cellulose. © 2012 Society of Chemical Industry     

D‐Lactic acid production from waste cardboard

The effects caused by alkaline treatment on the susceptibility of waste cardboard to enzymatic hydrolysis have been studied. Optimised conditions leading to extensive saccharification of both cellulose (870 g kg^?1 conversion) and hemicelluloses (845 g kg^?1 conversion) were identified. Samples treated under selected operational conditions were employed for producing D ‐lactic acid by simultaneous saccharification and fermentation (SSF) in media containing cellulases, β‐glucosidase and Lactobacillus coryniformis ssp torquens cells. SSF fed‐batch experiments led to D ‐lactic acid concentrations up to 23.4 g dm^?3 at a product yield of 514 g lactic acid kg^?1 of potential glucose and a volumetric productivity of 0.48 g dm^?3 h^?1. Copyright © 2004 Society of Chemical Industry     

Effect of several factors on peracetic acid pretreatment of sugarcane bagasse for enzymatic hydrolysis

BACKGROUND: Lignocellulose should undergo pretreatment to enhance its enzymatic digestibility before being saccharified. Peracetic acid (PAA) is a strong oxidant that can remove lignin under mild conditions. The sulfuric acid in the PAA solution also can cause degradation of hemicelluloses. The objective of the present work is to investigate the effect of several factors on peracetic acid pretreatment of sugarcane bagasse. RESULTS: It was found that PAA charge, liquid/solid (l/s) ratio, temperature, time, interactions between PAA charge and l/s ratio, temperature and time, all had a very significant effect on the enzymatic conversion ratio of cellulose. The relative optimum condition was obtained as follows: PAA charge 50%, l/s ratio 6:1, temperature 80 °C and time 2 h. More than 80% of the cellulose in bagasse treated under the above conditions was converted to glucose by cellulase of 20 FPU g^?1 cellulose. Compared with H₂SO₄ and NaOH pretreatments under the same mild conditions, PAA pretreatment was the most effective for enhancement of enzymatic digestibility. CONCLUSION: PAA pretreatment could greatly enhance the enzymatic digestibility of sugarcane bagasse by removing hemicelluloses and lignin, but removal of lignin was more helpful. This study can serve as a step to further optimization of PAA pretreatment and understanding the mechanism of enhancement of enzymatic digestibility. Copyright © 2007 Society of Chemical Industry     

Swollenin pre-conditioning: optimization studies and application aiming at d-lactic acid production from sugarcane bagasse

The enzymatic hydrolysis still stands as a challenge regarding the use of renewable feedstocks, as well as of lignocellulosic materials. The present work reports optimization of swollenin addition to pretreated sugarcane bagasse, in a step prior to the enzymatic hydrolysis, named pre-conditioning. Also, it describes further fermentation of the hydrolyzed material to d-lactic acid. Trichoderma harzianum enzymatic cocktail was produced from pretreated sugarcane bagasse, while swollenin was produced using Aspergillus niger as a host for recombinant protein expression. For pre-conditioning optimization, a Central Composite Rotatable Design was applied and validated. The optimized conditions were used to produce the hydrolysate that was fermented to D-lactic acid by Lactobacillus coryniformis subsp. torquens. It could be observed that pre-conditioning effectively leads to improvements in glucose release: 62% of hydrolysis efficiency. Besides, it was possible to use the produced hydrolysate to obtain d-lactic acid, with a yield of 1.34?g/g and a productivity of 1.59?g/L h^?1.     

Fermentative production of fumaric acid from Eucalyptus globulus wood hydrolyzates

Fumaric acid (FA) was produced from Eucalyptus globulus wood by successive steps of hydrothermal processing (to solubilize hemicelluloses and to increase the susceptibility of solids to enzymatic hydrolysis), enzymatic hydrolysis and fermentation with Rhizopus arrhizus DSM 5772. For comparative purposes, additional fermentations were carried out using synthetic media. Single stage fermentation of synthetic media led to a medium containing 11.8 g FA L^?1 (Y_P/S = 0.60 g g^?1). Operating in fed batch mode, the fourth stage increased the FA concentration from 19.7 up to 43.6 g L^?1 (Y_P/S = 0.71 g g^?1). Hydrolyzate fermentation in a single stage resulted in lower fumaric acid concentration (9.65 g L^?1) and yield (0.35 g g^?1). Additional fermentations were carried out in media made with hydrolyzates subjected to membrane processing, adsorption or ion exchange. The highest yield (Y_P/S = 0.44 g g^?1) was reached in media made up of ion‐exchange treated hydrolyzates and a commercial glucose solution in proportion 85/15 w/w. Copyright © 2011 Society of Chemical Industry     

Catalytic organosolv fractionation of willow wood and wheat straw as pretreatment for enzymatic cellulose hydrolysis

BACKGROUND: Ethanol‐based organosolv fractionation of lignocellulosic biomass is an effective pretreatment technology for enzymatic cellulose hydrolysis to produce sugars and lignin within a biorefinery. This study focuses on the catalytic effect of H₂SO₄, HCl, and MgCl₂ on organosolv pretreatment of willow wood and wheat straw. RESULTS: The use of catalysts improved fractionation of both feedstocks. The maximum enzymatic cellulose digestibility obtained was 87% for willow wood (using 0.01 mol L^?1 H₂SO₄ as catalyst) and 99% for wheat straw (0.02 mol L^?1 HCl). Non‐catalytic organosolv fractionation at identical conditions resulted in 74% (willow wood) and 44% (wheat straw) glucose yield by enzymatic hydrolysis. Application of catalysts in organosolv pretreatment was particularly effective for wheat straw. The influence of the acid catalysts was found to be primarily due to their effect on the pH of the organosolv liquor. Acid catalysts particularly promoted xylan hydrolysis. MgCl₂ was less effective than the acid catalysts, but it seemed to more selectively improve delignification of willow wood. CONCLUSION: Application of catalysts in organosolv pretreatment of willow wood and wheat straw was found to substantially improve fractionation and enzymatic digestibility. The use of catalysts can contribute to achieving maximum utilization of lignocellulosic biomass in organosolv‐based biorefineries. Copyright © 2011 Society of Chemical Industry     

Optimization of extraction of bulk enzymes from spent mushroom compost

The profiling of ligninase, hemicellulase and cellulase of Pleurotus sajor‐caju after inoculation of spawn in bags containing sawdust was done at monthly intervals for a period of 6 months. Xylanase (EC 3.2.1.8) was produced throughout the 6 months studied with the productivity range from 5.60 to 7.51 U g^?1. Cellulase (EC 3.2.1.4) and β‐glucosidase (EC 3.2.1.21) productivities were highest at 4 months, producing 3.31 U g^?1 and 121.13 U g^?1 respectively. Laccase (EC 1.10.3.2) productivity was highest at 2 months with a value of 7.59 U g^?1. Lignin peroxidase (EC 1.11.1.14) productivity was highest at 5 months with a value of 206.20 U g^?1. Total soluble proteins were highest at 4 months with a value of 0.139 mg cm^?3. The profiling of lignin peroxidase in 5‐month‐old spent mushroom compost was monitored over a period of 10 months. It was observed that lignin peroxidase was produced throughout the period but productivity was variable. The average lignin peroxidase productivity ranged from 30 to 110 U g^?1. The activities of the enzymes extracted in tap water at pH 8.4 were comparable to that extracted in 50 mmol sodium citrate buffer at pH 4.8 and distilled water at pH 5.2 at 4 °C using an incubator shaker at 200 rpm for 18 h. The optimum extraction time was 1 h using an incubator shaker at 4 °C. When an incubator shaker was used, there was no significant difference in the recovery of xylanase, cellulase and laccase at different pH values at 4 °C and 28 °C. No significant difference was observed in the recovery of β‐glucosidase using an incubator shaker at different pH values at 4 °C although the enzyme recovery was slightly higher at pH 8.12, with a value of 29.27 U g^?1. The optimum extraction of β‐glucosidase was at pH 4 at room temperature using an incubator shaker. For the lignin peroxidase enzyme, the optimum pH for extraction was 6 at 4 °C and pH 7 at room temperature using an incubator shaker at 200 rpm for 1 h. Homogenization for 8 min at 8000 rpm using tap water at pH 4 had an advantage over the use of the incubator shaker for the extraction as high titers of enzymes were recovered. Copyright © 2003 Society of Chemical Industry     

Hydrolysis of carboxymethylcellulose with mixtures of cellulase and β‐1,4‐glucosidase

We studied the hydrolysis of carboxymethylcellulose at 50 °C and pH 4.9 with a commercial preparation of cellulase (Celluclast) supplemented with a commercial β‐1,4‐glucosidase product (Novozym). The initial concentration of carboxymethylcellulose was varied between 2 and 12.5 kg m^?3 for assays with Celluclast and two Novozym/Celluclast ratios (0.5 and 1). We determined the conversion to glucose and the overall conversion in terms of glucose equivalent. Conversion to glucose turned out to be directly proportional to the product of experimental time multiplied by the concentration of Celluclast and the constant of proportionality increased concomitantly with the concentration of Novozym. Overall conversion remained unaffected by the concentration of Novozym. © 2001 Society of Chemical Industry     

Effects of butyric acid stress on anaerobic sludge for hydrogen production from kitchen wastes

BACKGROUND: Anaerobic digestion is an alternative technology to achieve the dual benefits of hydrogen production and waste stabilization from kitchen wastes. In this work, the butyric acid stress on anaerobic sludge was investigated in order to improve the tolerance of sludge against organic acids, and to enhance hydrogen accumulation. RESULTS: The tolerance of butyric acid in anaerobic sludge increased with the stress concentration, however, it decreased at concentrations greater than of 4.0 g L^?1. The maximum hydrogen yield reached 63.72 mL g^?1 VS at 4.0 g L^?1 stress, representing an increase of 114% compared with the control group. The concentration of volatile solids (VS) of the sludge and SCOD increased steadily with time up to 20 h. At 4.0 g L^?1 butyric acid stress, the maximum activity of β‐glucosidase, BAA‐hydrolysing protease and dehydrogenase enzyme were 14912.1 µmol PNP g^?1 TS h^?1, 134.14 µmol NH₄‐N g^?1 TS h^?1 and 7316.42 µg TF g^?1 TS h^?1, which were 2.78, 1.90 and 2.01 times that of the control, respectively. CONCLUSIONS: The feasibility of butyric acid stress on anaerobic sludge to increase hydrogen production from kitchen wastes was demonstrated. Remarkably, 4.0 g L^?1 butyric acid stress was found to be favorable for improving the tolerance of butyric acid in sludge as well as hydrogen yield in the experiment. Copyright © 2010 Society of Chemical Industry     

Wet oxidation pre‐treatment of woody yard waste: parameter optimization and enzymatic digestibility for ethanol production

Woody yard waste with high lignin content (22% of dry matter (DM)) was subjected to wet oxidation pre‐treatment for subsequent enzymatic conversion and fermentation. The effects of temperature (185–200 °C), oxygen pressure (3–12 bar) and addition of sodium carbonate (0–3.3 g per 100 g DM biomass) on enzymatic cellulose and hemicellulose (xylan) convertibility were studied. The enzymatic cellulose conversion was highest after wet oxidation for 15 min at 185 °C with addition of 12 bars of oxygen and 3.3 g Na₂CO₃ per 100 g waste. At 25 FPU (filter paper unit) cellulase g^?1 DM added, 58–67% and 80–83% of the cellulose and hemicellulose contained in the waste were converted into monomeric sugars. The cellulose conversion efficiency during a simultaneous saccharification and fermentation (SSF) assay at 10% DM was 79% for the highest enzyme loading (25 FPU g^?1 DM) while 69% conversion efficiency was still reached at 15 FPU g^?1 DM. Total carbohydrate recoveries were high (91–100% for cellulose and 72–100% for hemicellulose) and up to 49% of the original lignin and 79% of the hemicellulose could be solubilized during wet oxidation treatment and converted into carboxylic acids mainly (total carboxylic acids = 3.1–7.4% on DM basis). Copyright © 2004 Society of Chemical Industry     

Simultaneous saccharification and fermentation of alkaline-pretreated corn stover to ethanol using a recombinant yeast strain

Bio-ethanol converted from cheap and abundant lignocellulosic materials is a potential renewable resource to replace depleting fossil fuels. Simultaneous saccharification and fermentation (SSF) of alkaline-pretreated corn stover for the production of ethanol was investigated using a recombinant yeast strain Saccharomyces cerevisiae ZU-10. Low cellobiase activity in Trichoderma reesei cellulase resulted in cellobiose accumulation. Supplementing the simultaneous saccharification and fermentation system with cellobiase greatly reduced feedback inhibition caused by cellobiose to the cellulase reaction, thereby increased the ethanol yield. 12 h of enzymatic prehydrolysis at 50 °C prior to simultaneous saccharification and fermentation was found to have a negative effect on the overall ethanol yield. Glucose and xylose produced from alkaline-pretreated corn stover could be co-fermented to ethanol effectively by S. cerevisiae ZU-10. An ethanol concentration of 27.8 g/L and the corresponding ethanol yield on carbohydrate in substrate of 0.350 g/g were achieved within 72 h at 33 °C with 80 g/L of substrate and enzyme loadings of 20 filter paper activity units (FPU)/g substrate and 10 cellobiase units (CBU)/g substrate. The results are meaningful in co-conversion of cellulose and hemicellulose fraction of lignocellulosic materials to fuel ethanol.     

Preparation of Sesaminol from Sesaminol Triglucoside by β-Glucosidase and Cellulase Hydrolysis

Sesaminol triglucoside (i.e., 2,6‐O‐di(β‐d ‐glucopyranosyl)‐β‐d ‐glucopyranosyl sesaminol, STG) is a physiologically active substance obtained abundantly from defatted sesame cake. Since, the industrial preparation of sesaminol from STG has not been reported previously, the aim of this research was to prepare sesaminol by hydrolysis of STG using β‐glucosidase and cellulase. Under the optimal conditions of total enzyme dosage 100 μL (8,000.72 U), the ratio of β‐glucosidase and cellulase 20:80 (v/v) (0.72:8,000, U/U), reaction time 24 h, substrate concentration 6 mg/mL, reaction temperature 50 °C, and reaction system pH 4.8, the yield of sesaminol was 48.9 %. Further, sesaminol and other hydrolysis products (sesaminol diglucoside and sesaminol monoglucoside) were successfully determined by high performance liquid chromatography and electrospray ionization/mass spectrometry.