Maximum Total Reducing Sugar Research Articles

Utilization of rice straw for parallel production of sugars rich extract and paper

Abstract Complete utilization of different agricultural wastes is a great challenge before human society. The present study reports the valorization of rice straw for simultaneous production of reducing sugars and paper. The rice straw was first pre-extracted with water under different reaction conditions sequentially followed by papermaking. A maximum total reducing sugars (TRS) upto 12.38 % was extracted through aqueous pre-treatment. The pulped biomass was assessed for paper properties viz., tensile index, tear index, burst index, Kappa no. and brightness. For untreated rice straw tensile index, tear index and burst index were recorded within a range of 30.9–35.8 N m/g; 2.25–2.62 mN m2/g and 1.91–2.35 kN/g respectively where as it were ranged from 31.1 to 33.7 N m/g, 2.02–2.51 mN m2/g and 1.78–2.08 kN/g respectively for pretreated rice straw. Moreover, for untreated rice straw, kappa number and brightness were recorded in a range from 20.7 to 26.6 and 32.4 to 36.7 % ISO respectively, whereas for pre-treated rice straw it ranged from 19.1 to 26.3 and 31.6 to 35.5 % ISO respectively. High performance liquid chromatography (HPLC) analysis and field emission gun scanning electron microscopy (FESEM) were further employed during the study. In overall, extraction of underutilized sugars prior to pulping may prove as an efficient route for apt utilization of sugars followed by papermaking in near future.

Optimization of the Hydrolysis Process of Microalgae Porphyridium cruentum Biomass with Variations of Hydrochloric Acid Concentration, Temperature, and Time using Response Surface Methodology (RSM)

Microalgae Porphyridium cruentum has potential as a raw material for bioethanol production because it has a high carbohydrate content. These carbohydrates can be broken down into reducing sugars through the hydrolysis process. The reducing sugar obtained will be used as a substrate in the production of bioethanol. This study aimed to produce a substrate with the best-reducing sugar indicator and to determine the optimum conditions for hydrolysis of P. cruentum microalgae biomass following the Box-Behnken statistical experimental design, using Response Surface Methodology (RSM). The parameters of the optimized hydrolysis process were HCl concentration (2 - 0.2 N), temperature (60 -120 ˚C), and hydrolysis time (30-180 min). The optimum conditions that have been achieved using RSM are an HCl concentration of 1.91 N, a temperature of 60 °C, and a hydrolysis time of 180 min were predicted a maximum total reducing sugar production of 810 mg/L. The experimental result of total reducing sugar obtained at optimum conditions was 895 mg/L, which was well close to the predicted value, verifying the appropriateness of the model.Abstract is informed about the statements of the problem, methods, scientific finding results and conclusion concisely

A Comparison of Dilute Aqueous Isethionic Acid and Sulfuric Acid in Hydrolysis of Three Different Untreated Lignocellulosic Biomass Varieties.

Efficient catalytic hydrolysis of lignocellulosic biomass to sugars is a major challenge in the production of sustainable biofuels and chemical feedstocks. In this study isethionic acid was compared with H2SO4 for hydrolysis of polysaccharides in corn stover, switch grass, and poplar. The catalytic activities of acids were compared by analysis of total reducing sugar (TRS) and glucose yields in a sequence of experiments in water at 90-190 °C using 0.050 mol of H+/L isethionic acid and H2SO4. In comparison to using H2SO4, the use of isethionic acid catalyst lowered the maximum TRS percent yield temperatures by 25, 24, and 21% for corn stover, switch grass, and poplar. A similar effect was observed for glucose percent yields as well. This temperature reduction is due to lowering of the activation energy in the polysaccharide depolymerization reaction and most likely due to hydrogen-bonding-type dipolar interactions between the isethionic acid -OH group and -OH groups in biomass polysaccharides.

Rugulopteryx okamurae: Assessment of its potential as a source of monosaccharides for obtaining bio-products

Beach-cast seaweed of the invasive brown macroalga Rugulopteryx okamurae was used in this study as raw material to obtain fermentable sugars, which can be converted into high added-value products. The dietary fibre composition of this macroalgae was determined and compared to other brown and red macroalgae, showing one of the highest proportions of dietary fibre (27.3 %) and cellulose (13.6 %). Therefore, the enzymatic hydrolysis of R. okamurae could lead to obtaining hydrolysates with a high concentration of reducing sugars. The main hydrolysis variables (biomass loading, enzyme dose and stirring rates) and the operation mode (fed-batch versus batch) were evaluated to maximize the sugar concentration. Thus, a maximum total reducing sugar concentration of 13.7 g/L was obtained at the optimum conditions: biomass loading of 10 % (w/v), 50 FPU/g biomass, 250 rpm and operating in batch mode. In addition, a kinetic model has been developed to describe the enzymatic hydrolysis of biomass. The model, unlike first-order kinetics, includes a specific term considering the enzyme diffusion through the solid biomass. The proposed kinetic model leads to better fitting of experimental data than the first-order model, especially for long incubation times.

Lipid bioproduction through optimization of thermal diluted acid pretreatment on native grass using Yarrowia lipolytica

In the present study, thermal-dilute sulfuric acid pretreatment was performed on native grass (Cyperus distans) biomass for achieving optimized simple sugar recovery. Lipid bioproduction was performed using Yarrowia lipolytica from pretreated native grass biomass. Optimization of thermal diluted acid pretreatment on native grass biomass was investigated using one factor at a time (OFAT) method and response surface methodology. The maximum total reducing sugar (34.26 ± 1.55 g/L) in native grass hydrolysate was obtained at 163.8 °C, 1.57 % (v/v) of sulfuric acid concentration for 21 min. Minimization of formed inhibitors was performed using detoxification. About 11.64 ± 0.84 g/L of lipid was produced with 65.52 % (w/w) of lipid content after 96 h from detoxified native grass hydrolysate using Y. lipolytica in a 5 L fermentor. Result revealed that optimization of thermal diluted acid pretreatment on native grass biomass is an efficient method for lipid production using Y. lipolytica.

Production of Polyhydroxyalkanoates through Soybean Hull and Waste Glycerol Valorization: Subsequent Alkaline Pretreatment and Enzymatic Hydrolysis

Alkaline pretreatment and sequential enzymatic hydrolysis of soybean hull were investigated to obtain fermentable sugars for polyhydroxyalkanoates production along with residual glycerol as low-cost carbon sources. Soybean hull is composed of approximately 32% cellulose, 12% hemicellulose, 6% lignin, and 11% protein. Alkaline pretreatment was carried out with 2% NaOH concentration, 10% (w/v) biomass loading, and 60 min incubation time in an autoclave at 120 °C. The response surface methodology (RSM) based on the central composite design (CCD) tool was employed to optimize the enzymatic hydrolysis process, where the variables of biomass loading, enzymes’ concentration, and time were considered. The maximum total reducing sugars concentration obtained was 115.9 g∙L−1 with an enzyme concentration of 11.5 mg protein/g dry substrate for enzyme preparation B1, 2.88 mg protein/g dry substrate for XylA, and 57.6 U/g dry substrate for β-glucosidase, after 42 h at 45 °C, and pH was 4.5. Subsequently, the saccharification step was conducted by increasing the processing scale, using a 1 L tank with stirring with a controlled temperature. Implementing the same enzyme concentrations at pH 4.5, temperature of 45 °C, 260 mL working volume, and incubation time of 42 h, under fed-batch operation with substrate feeding after 14 h and 22 h, a hydrolysate with a concentration of 185.7 g∙L−1 was obtained. Initially, to verify the influence of different carbon sources on Cupriavidus necator DSMz 545 in biomass production, batch fermentations were developed, testing laboratory-grade glucose, soybean hull hydrolysate, and waste glycerol (a by-product of biodiesel processing available in large quantities) as carbon sources in one-factor-at-a-time assays, and the mixture of soybean hull hydrolysate and waste glycerol. Then, the hydrolysate and waste glycerol were consumed by C. necator, producing 12.1 g∙L−1 of biomass and achieving 39% of polyhydroxyalkanoate (PHB) accumulation. To the best of our knowledge, this is the first time that soybean hull hydrolysate has been used as a carbon source to produce polyhydroxyalkanoates, and the results suggest that this agro-industrial by-product is a viable alternative feedstock to produce value-added components.

Synthesis of gold nanoparticles using bacterial cellulase and its role in saccharification and bioethanol production from aquatic weeds

In this investigation, gold nanoparticles (AuNPs) were synthesized using cellulase (partially purified from Glutamicibacter arilaitensis strain ALA4) as reducing agent. The biosynthesis of AuNPs was confirmed by observing the appearance of purple colour solution with surface plasmon resonance absorption peak (λmax) at 574 nm. The SEM analysis showed the synthesis of gold nanocrystals with an average size of 5–7 nm. Cellulase was partially purified from strain ALA4 using standard protocols, and further immobilized on AuNPs for assessing its role in the saccharification of alkali (4% w/v NaOH) pre-treated aquatic weeds (Alternanthera philoxeroides and Brachiaria mutica) biomass. The pre-treated biomass of A. philoxeroides exhibited maximum total reducing sugar (TRS) yield of 18.95 ± 0.18 mg/g at 72 h. The pre-treated biomass exhibited increased saccharification degree of 38.25 ± 0.8, 49.05 ± 0.7, 67.05 ± 0.7, 85.27 ± 0.8, and 67.99 ± 0.8% from 12 to 96 h. Likewise, the pre-treated biomass of B. mutica exhibited maximum TRS yield of 20.98 ± 0.17 mg/g at 72 h. The pre-treated biomass exhibited increased saccharification degree of 44.46 ± 0.7, 55.53 ± 0.8, 73.26 ± 0.7, 94.41 ± 0.8, and 73.3 ± 0.7% from 12 to 96 h. Bioethanol production from pre-treated aquatic weeds were estimated by simultaneous saccharification and fermentation process using yeast cells immobilized on sodium alginate. Ethanol content was estimated using Gas Chromatography. The yeast cells immobilized in calcium alginate beads showed ethanol production of 45.09 and 50.1% from NaOH pre-treated A. philoxeroides and B. mutica biomass, respectively. Findings of this study suggested pronounced role of bacterial cellulase-assisted-synthesized AuNPs in biofuel industries for the successful production of bioethanol from distinct aquatic weeds biomass in a cost-effective manner in future.

Saccharification of alkali pre-treated aquatic weeds biomass using partially purified cellulase immobilized on different matrices

Enzyme immobilization has gained considerable significance among other techniques for improving the saccharification ability of disparate lignocellulosic biomasses. In this investigation, the partially purified cellulase (approximately 38 kDa) from Glutamicibacter arilaitensis strain ALA4 was immobilized on various matrices (calcium alginate, k-carrageenan, agar-agar, and gelatin) for evaluating saccharification ability of alkali (4% w/v NaOH) pre-treated aquatic weeds (Alternanthera philoxeroides and Brachiaria mutica) biomass. The immobilization of cellulase using various matrices showed improvement in total reducing sugar (TRS) yield and saccharification efficiency of biomasses in the order of calcium alginate > gelatine > k-carrageenan > agar-agar. Calcium alginate immobilized cellulase exhibited maximum TRS and saccharification efficiency of 17.85±0.18 mg/g and 80.32±0.6%, respectively from pre-treated A. philoxeroides biomass. On the other hand, calcium alginate immobilized cellulase exhibited maximum TRS and saccharification efficiency of 19.51±0.2 mg/g and 87.79±0.6%, respectively from pre-treated B. mutica biomass. Further, the thermo-alkali stability, storage stability, and reusability of calcium alginate immobilized cellulase were determined using standard methodologies. The immobilized cellulase showed higher thermo-alkali stability than free cellulase with residual activities of 46.36±3.6 and 40.55±2.6% at 65 °C and pH 10.0, respectively. Likewise, the immobilized cellulase retained its activity for at least 22–24 days of storage at 4 °C. Most importantly, the immobilized enzyme maintained its saccharification ability towards pre-treated A. philoxeroides and B. mutica up to 4th and 5th cycle, respectively. In conclusion, bacterial cellulase can be immobilized on different matrices, particularly calcium alginate for improving the TRS yield and saccharification efficiency of aquatic weeds biomasses.

Integrated bioprocess for bio-ethanol production from watermelon rind biomass: Ultrasound-assisted deep eutectic solvent pretreatment, enzymatic hydrolysis and fermentation

Herein, the potential of watermelon rind (WMR) biomass for bio-ethanol production through an integrated bioprocess consisting of combinative sequential ultrasonication and deep eutectic solvent (DES) pretreatments, enzymatic hydrolysis and fermentation was investigated. For the improvement of the efficiency of the WMR conversion into bio-ethanol, the effectiveness of the ultrasonic-assisted DES pretreatment on bio-ethanol yield was studied by optimization, adopting Central Composite Rotatable Design. Glucose was the most dominant sugar in the WMR biomass which enhanced its suitability as cheap carbon source for fermentation process. Maximum glucose and total reducing sugar yields of 60.17% and 83.03% were respectively obtained, and the enzymatic hydrolysis efficiencies ranged from 75.79 to 91.13%. The bio-ethanol yield ranged from 0.276 to 0.458 gg−1 raw WMR, corresponding to fermentation efficiencies of 54.12–89.80%, with the maximum obtained at ultrasonication power 180 W, ultrasonication frequency 40 kHz, ultrasonication time 40 min, DES reaction temperature 120°C and DES reaction time 180 min. Results showed that all the pretreatment factors considered had significant effect on bio-ethanol yield. It was established that combinative pretreatment was efficient for delignification, solubilization and hydrolysis of cellulose and hemicellulose into monomeric sugars by removing hemicellulose from the cellulose fibers. This enhanced fermentable sugar recovery, which consequently increased bio-ethanol yield.

Assessment of reducing sugars production from agro-industrial wastes by batch and semicontinuous subcritical water hydrolysis

Reducing sugars produced from agro-industrial wastes by means of hydrolysis represent a promising alternative of chemicals and energy. Yet, large scale production still struggles with several factors involving process complexity, sugars degradation, corrosion, enzyme recyclability, and economic feasibility. More recently, sub and supercritical water hydrolysis has been reported for the production of reducing sugars as a readily available alternative to acid and enzymatic biomass hydrolysis. Accordingly, in this work, the results of batch and semicontinuous lab scale subcritical water hydrolysis experiments of agro-industrial wastes of pea pot and corn stover are discussed. Experiments were carried in the temperature range 250 to 300 °C, pressures up to 3650 psi, residence times up to 30 minutes in batch mode operation, or water flowrates up to 12 mL/min in semicontinuous mode operation. Produced sugars were assessed in the effluent of each experimental run by means of dinitrosalicilic acid method (DNS). A maximum total reducing sugar (TRS) yield of 21.8% was measured for batch pea pot subcritical water hydrolysis experiments at 300°C, 15 minutes, 3650 psi, and 1:6 biomass to water mass ratio. Semicontinuous subcritical water hydrolysis of corn stover showed a maximum TRS accumulated yield of 19% at 290 °C, 1500 psi, and water flowrate of 9 mL/min. The results showed the feasibility of producing reducing sugars from agro-industrial wastes currently discarded through subcritical hydrolysis.

Conversion of Babool wood residue to 5-Hydroxymethyl Furfural: Kinetics and Process modelling

This study proposes an integrated approach for the formation of total reducing sugars (TRS) and 5-hydroxymethyl furfural (5-HMF) from forestry biomass. Detailed kinetics was studied using an irreversible series model and the developed kinetic model is congruent with the experimental data. The obtained rate constants were also applied to gain insight for designing continuous reactor configurations. Maximum TRS (32.28%) and 5-HMF yield (42.32%) was obtained in 67.13 min and 311.62 min at 120 °C using single-stage CSTR whereas complete conversion of TRS was observed in 17.03 min with significant 5-HMF yield (23.68%) in 39.07 min at 120 °C using two equal-sized CSTR in series. Also, maximum TRS yield (30.61%) and 5-HMF yield (58.41%) was observed in 67.13 min and 193.38 min respectively using single-stage PFR. The proposed model for Babool wood hydrolysis will be valuable to facilitate the cost-effective and sustainable conversion of waste biomass to bio-based fuels.

Hydolysis of multi substrate biomass using para-toluenesulphonic acid for bioethanol production: A promising option over the sulfuric acid treatment

The municipal and agricultural wastes are promising source of ligniocellulosic biomasses (LBs) for bioethanol production. However, the pretreatment-hydrolysis (P–H) of LB is the most difficult process in bioethanol production due to high crystallinity of LB compositional structures. In this study, p-toluenesulphonic acid (PTSA) was investigated for P–H of multi-substrate (MS) sample of LBs. Five alternative MS samples were prepared from 10 single LBs. Based on the total reducing sugar yield, one of the MS was selected for optimization experiment. The factors affecting P–H (acid concentration, time and temperature) were optimized to compare catalytic activity of PTSA and H2SO4. Under the optimized conditions, maximum total reducing sugar (TRS) yield of 95.89 and 78.26% was obtained using PTSA and H2SO4, respectively. Mass production of hydrolysate was carried out using both catalysts at a substrate load of 50 g.L−1 and fermented at an optimum yeast load of 10% (v/v). The ethanol yield from the hydrolysates of PTSA treatment was 16.89 g L−1 (74.5%) and from H2SO4 was 13.17 g L−1 (70.9%) at 48 & 56 h fermentation time, respectively. The PTSA surpassed the conventional method of treatment (H2SO4) both in TRS and ethanol yield. The efficiency of PTSA can be noticed in that one third of the acid concentration required in sulfuric acid treatment was used in PTSA to obtain 96% of TRS at lower temperature. This study revealed the potential of aqueous PTSA for the hydrolysis of a mixture of feedstocks which is much more complex and challenging than treating a single substrate.

Response surface methodology (RSM) for optimization of thermochemical pretreatment method and enzymatic hydrolysis of deodar sawdust (DS) for bioethanol production using separate hydrolysis and co-fermentation (SHCF)

In the present work, Cedrus deodara (deodar) sawdust abbreviated as DS was subjected to thermochemical pretreatment followed by enzymatic hydrolysis and fermentation for bioethanol production. Response surface methodology (RSM) based on central composite design (CCD) tool was employed to optimize dilute acid pretreatment method (at 121 °C temperature and 1-bar pressure) and enzymatic hydrolysis processes. Factorial design of experiments used chemical concentration, incubation time, and biomass loading to optimize thermochemical pretreatment method using dilute acid concentration. Maximum total reducing sugar (TRS) concentration (13.62 g/L) was obtained using optimized conditions (1.5% HCl concentration, 10% biomass loading and 30-min incubation time). These significant studies were subjected to optimize enzymatic hydrolysis process using the CCD tool of the RSM where cellulase loading, xylanase loading, pH, and temperature were taken into consideration. TRS concentration obtained was 29.20 g/L after 48 h with enzyme loading of 9 U/g biomass, each for cellulase and xylanase enzyme at pH 5.0 and 30 °C temperature. Fermentation conditions for enzymatically hydrolyzed DS revealed that at 10% (v/v) yeast inoculum concentrations (Saccharomyces cerevisiae (MTCC-36) and Pichia stipitis (NCIM-3498)) after 24-h fermentation time and pH 5.0, bioethanol concentration was 14.25 g/L with 95.68% conversion efficiency. Characterization studies for native and pretreated DS by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM) analyses revealed delignification rate of 30.93% of DS biomass under optimized thermochemical pretreatment conditions. Statistical studies for optimization of pretreatment and enzymatic hydrolysis for bioethanol production stated DS sawdust (a furniture industry waste) as a potential substrate for biofuel production.

Evaluation of the Interactive Effect Pretreatment Parameters via Three Types of Microwave-Assisted Pretreatment and Enzymatic Hydrolysis on Sugar Yield

This study aims to evaluate the sugar yield from enzymatic hydrolysis and the interactive effect pretreatment parameters of microwave-assisted pretreatment on glucose and xylose. Three types of microwave-assisted pretreatments of sago palm bark (SPB) were conducted for enzymatic hydrolysis, namely: microwave-sulphuric acid pretreatment (MSA), microwave-sodium hydroxide pretreatment (MSH), and microwave-sodium bicarbonate (MSB). The experimental design was done using a response surface methodology (RSM) and Box–Behenken Design (BBD). The pretreatment parameters ranged from 5–15% solid loading (SL), 5–15 min of exposure time (ET), and 80–800 W of microwave power (MP). The results indicated that the maximum total reducing sugar was 386 mg/g, obtained by MSA pretreatment. The results also illustrated that the higher glucose yield, 44.3 mg/g, was found using MSH pretreatment, while the higher xylose yield, 43.1 mg/g, resulted from MSA pretreatment. The pretreatment parameters MP, ET, and SL showed different patterns of influence on glucose and xylose yield via enzymatic hydrolysis for MSA, MSH, and MSB pretreatments. The analyses of the interactive effect of the pretreatment parameters MP, ET, and SL on the glucose yield from SPB showed that it increased with the high MP and longer ET, but this was limited by low SL values. However, the analysis of the interactive effect of the pretreatment parameters on xylose yields revealed that MP had the most influence on the xylose yield for MSA, MSH, and MSB pretreatments.

Glycerol production by the UV-mutant marine yeast Wickerhamomyces anomalus HH16-MU15 via simultaneous saccharification and fermentation of fruit peels

Agro-industrial wastes in Egypt are indefinite and sustainable substrate for production of numerous industrially significant products. Using of these wastes as raw materials can reduce both the production cost and the environmental pollution. The present research aims to produce glycerol from fruit peels by the UV-mutant marine yeast Wickerhamomyces anomalus HH16-MU15. Fruits (banana, orange, mango and pomegranate) peels were pretreated by mechanical and hydrothermal methods before their fermentation into glycerol. The maximum total reducing sugars (5.792 ± 0.16gl-1) was obtained from mango peels followed by orange peels (5.33 ± 0.21gl-1) after their hydrothermally pretreatment. After fermentation, the maximum cellulase activity (8.911 Uml-1), total reducing sugars (48.59 gl-1) and glycerol yield (35.25 gl-1) by W. anomalus HH16-MU15 were achieved in the hydrolysate of hydrothermally pretreated orange peels at 96 hrs. The current investigation suggests the using of orange peels for production of glycerol and other valuable products by W. anomalus HH16-MU15.

Statistically designed cellulase mixture for saccharification of pretreated Sorghum durra stalk

The potential of least explored Sorghum durra as a feedstock for enzymatic saccharification in bioethanol production was evaluated as only one report is available. The pretreatment specific, optimization of saccharification of Sorghum durra stalk (Sds) was carried out. The concentrations of crude recombinant endoglucanase (BaGH5-UV2), cellobiohydrolase (CtCBH5A) and β-glucosidase (CtGH1) in cocktail were optimized for saccharification of acid or base pretreated Sds by using mixture design approach. Optimized percentage ratio of BaGH5-UV2, CtCBH5A and CtGH1 with total enzyme loading 2000 U/g of pretreated Sds for acid pretreated Sds was 43.1:10.0:46.9 and for base pretreated Sds was 80:10:10 at 48 h of saccharification. The base pretreated Sds showed 1.8-fold (165.6 mg/g of pretreated Sds) higher total reducing sugar (TRS) yield and 1.2-fold (81.7 mg/g of pretreated Sds) higher glucose yield than acid pretreated Sds. This low sugar yield from acid pretreated Sds was due to the presence of higher acid insoluble lignin content, 11.9 % (w/w) than the base pretreated biomass (2.2 %, w/w). In acid pretreated Sds, ANOVA data showed 3.7-fold higher F value (111.58) for BaGH5-UV2 and CtGH1 interaction than the base pretreated Sds. This indicated that the synergism between BaGH5-UV2 and CtGH1 for acid pretreated Sds was significantly higher. This was due to lower intact hemicellulose content (10.6 %, w/w) in acid pretreated Sds than base pretreated Sds (21.8 %, w/w). The optimized enzyme ratios for saccharification of acid pretreated Sds gave maximum TRS and glucose yield at 72 h, 113 and 85 mg/g of pretreated Sds, respectively, unlike base pretreated Sds at 96 h, 211 and 174 mg/g of pretreated Sds, respectively. These results showed that the ratio of cellulase enzymes in cocktail and their synergism depends on the type of pretreatment used for biomass. Thus, this in-house cocktail design specific to pretreatment can improve the biomass saccharification at large scale.

Novel strategies for glucose production from biomass using heteropoly acid catalyst

Abstract Bioethanol and direct glucose fuel cells pledged clean energy to the world. Cellulose depolymerization for glucose production has been a successful approach in bioethanol production. Heteropoly acids (HPAs) are strong Bronsted solid acid catalysts for biomass hydrolysis. Keggin type HPAs, namely, Silicotungstic acid (HSiW), Phosphotungstic acid (HPW), and Phosphomolybdic acid (HPMo), were used for the hydrolysis of lignocellulosic biomass to glucose. Five different biomass feedstocks, namely, miscanthus, sugarcane leaves, switchgrass, sunflower seeds, and bamboo leaves, were examined for the feasibility of total reducing sugar (TRS) yield through the composition analysis and catalytic biomass hydrolysis. Sunflower seeds contained the maximum holocellulose with 90.6%, and switchgrass contained the least i.e., 77.63%. Among the five biomass tested, switchgrass resulted in the highest TRS (5.77 wt/dry wt. %) with HPMo catalyst at a catalyst to biomass ratio of 30:100 (wt./wt. %), a reaction temperature of 120 °C for 3 h. The reaction parameters for depolymerization were optimized for all three HPAs, and the optimized conditions were 3 h and 120 °C. HPMo showed maximum TRS yield (5.77 wt/dry wt.%) among the three HPAs at 30:100 catalyst to biomass ratio. However, a catalyst to biomass ratio of 20:100 (wt./wt.%) was economical (5.25 wt/dry wt.%) for commercial application.

Enzymatic hydrolysis behavior on malt bagasse for fermentative sugar disposal in thermostatic and ultrasonic bath

AbstractThis study evaluated the effect of enzymatic hydrolysis on malt bagasse for fermentative sugar extraction in thermostatic and ultrasonic bath. The enzymatic reaction was performed using cellulase, α‐amylase, and amyloglucosidase (in separate and combined) on malt bagasse to analyze the hydrolysis effect. For this, a central composite rotational design was applied to evaluate the effect of solid:liquid (malt bagasse w/v) versus enzymatic concentration, considering cellulase, α‐amylase, and amyloglucosidase enzymes in mix solution, on fermentable sugars liberation. Then the kinetic fermentative sugars liberation was evaluated in a hydrolysis reaction using cellulase, α‐amylase, and amyloglucosidase (in separate and combined) after exposure in thermostatic and ultrasonic bath. From enzymatic mix, the maximum total reducing sugar (TRS) yield was 408.8 and 219.9 mg·g−1 in thermostatic and in ultrasound bath, respectively. Kinetic studies showed a TRS variation of 6 to 7 g·L−1 for all enzymes. Amyloglucosidase was more promising in assimilation of malt bagasse, responsible for 43% of sugar releasing. Briefly, a low‐cost procedure using thermostatic bath improved the hydrolysis reaction. The results from the experiments present a new application where malt bagasse can be employed showing the potential of this brewing industry residue in fomenting processes, as bioethanol production.

Assessment of combination of pretreatment of Sorghum durra stalk and production of chimeric enzyme (β-glucosidase and endo β-1,4 glucanase, CtGH1-L1-CtGH5-F194A) and cellobiohydrolase (CtCBH5A) for saccharification to produce bioethanol

Optimization of pretreatment and saccharification of Sorghum durra stalk (Sds) was carried out. The chimeric enzyme (CtGH1-L1-CtGH5-F194A) having β-glucosidase (CtGH1) and endo β-1,4 glucanase activity (CtGH5-F194A) and cellobiohydrolase (CtCBH5A) from Clostridium thermocellum were used for saccharification. Chimeric enzyme will save production cost of two enzymes, individually. Stage 2 pretreatment by 1% (w/v) NaOH assisted autoclaving + 1.5% (v/v) dilute H2SO4 assisted oven heating gave lower total sugar yield (366.6 mg/g of pretreated Sds) and total glucose yield (195 mg/g of pretreated Sds) in pretreated hydrolysate with highest crystallinity index 55.6% than the other stage 2 pretreatments. Optimized parameters for saccharification of above stage 2 pretreated biomass were 3% (w/v) biomass concentration, enzyme (chimera: cellobiohydrolase) ratio, 2:3 (U/g) of biomass, total enzyme loading (350 U/g of pretreated biomass), 24 h and 30 °C. Best stage 2 pretreated Sds under optimized enzyme saccharification conditions gave maximum total reducing sugar yield 417 mg/g and glucose yield 285 mg/g pretreated biomass in hydrolysate. Best stage 2 pretreated Sds showed significantly higher cellulose, 71.3% and lower lignin, 2.0% and hemicellulose, 12.2% (w/w) content suggesting the effectiveness of method. This hydrolysate upon SHF using Saccharomyces cerevisiae under unoptimized conditions produced ethanol yield, 0.12 g/g of glucose. Abbreviation: Ct-Clostridium thermocellum, Sds-Sorghum durra stalk, TRS-Total reducing sugar, HPLC-High performance liquid chromatography, RI-Refractive index, ADL-acid insoluble lignin, GYE-Glucose yeast extract, MGYP-Malt glucose yeast extract peptone, SHF-separate hydrolysis and fermentation, OD-Optical density, PVDF-Poly vinylidene fluoride, TS-total sugar, FESEM-Field emission scanning electron microscopy, XRD-X-ray diffraction, FTIR-Fourier transform infra-red spectroscopy and CrI-Crystallinity index.

Strategy to enhance the sugar production using recyclable inorganic salt for pre-treatment of oil palm empty fruit bunch (OPEFB)

Inorganic salts were used for the pretreatment of oil palm empty fruit bunches (OPEFB) to enhance the delignification and saccharification yield of OPEFB. The sequential pretreatment of OPEFB using sodium phosphate dodecahydrate (Na3PO4.12H2O) and zinc chloride (ZnCl2) proved to be an effective approach. OPEFB was delignified by 58.8%, producing a maximum total reducing sugar (TRS) yield of 0.97 g/g under optimum pretreatment conditions of 15% Na3PO4.12H2O, 60 min (30 min/stage) pretreatment time, 10% solid to liquid ratio, and pretreatment temperature of 121 °C. In addition, structural and morphological analysis of the pretreated OPEFB using field emission scanning electron microscope (FESEM), Fourier transform infrared (FTIR) spectroscopy, and X- ray diffraction (X-RD) revealed major structural changes, such as the generation of porous structure, which allows for better enzyme accessibility. Moreover, recycle experiments showed encouraging findings, as the spent pretreatment liquid with pH adjustment can be recycled efficiently for at least 5 times without a substantial decrease in its effectiveness.