Enzymatic Saccharification Of Sugarcane Bagasse Research Articles

Enhanced Production of Clean Fermentable Sugars by Acid Pretreatment and Enzymatic Saccharification of Sugarcane Bagasse

Sugarcane bagasse (SCB), an agro-industrial byproduct generated by a sugar mill, holds a substantial carbohydrate content of around 70 wt.%, comprising cellulose and hemicellulose. Saccharification plays a pivotal role in the conversion of SCB into second-generation (2G)-ethanol and valuable compounds, which is significantly aided by thermochemical pretreatments. In this study, SCB underwent diluted sulfuric acid pretreatment (2% H2SO4, 80 rpm, 200 °C, 20 min), resulting in the removal of 77.3% of the xylan. The hemicellulosic hydrolysate was analyzed to identify the sugars and degraded products acting as microbial inhibitors. The acid hydrolysate showed a xylose yield of 68.0% (16.4 g/L) and a yield of 3.8 g/L of acetic acid. Afterward, the hemicellulosic hydrolysate was concentrated 2.37 times to obtain a xylose-rich stream (39.87 g/L). The sequential detoxification, employing calcium oxide and activated carbon, removed the inhibitory compounds, including acetic acid, while preserving the xylose at 38.10 g/L. The enzymatic saccharification of cellulignin at 5% and 10% of the total solids (TSs) yielded comparable reducing sugar (RS) yields of 47.3% (15.2 g/L) and 47.4% (30.4 g/L), respectively, after 96 h, employing a 10 FPU/g enzyme loading of Cellic® CTec3 (Novozymes Inc. Parana, Brazil). In summary, these findings outline an integrated green chemistry approach aimed at addressing the key challenges associated with pretreatment, concentration, detoxification, and enzymatic hydrolysis to produce fermentable sugars.

SACARIFICACIÓN ENZIMÁTICA DE BAGAZO DE CAÑA DE AZÚCAR PRETRATADO CON PEROXIDO DE HIDROGENO PARA LA PRODUCCIÓN DE BIOETANOL

<p><strong>Background.</strong> Sugarcane (<em>Saccharum officinarum</em> L.) is one of the main crops in Mexico; during the harvest 2021-2022, 54.6 million tons of raw milled sugarcane were industrialized, ranking sixth in production worldwide. However, during processing, several products and co-products are generated, including sugarcane bagasse, that is used to produce electricity by combustion, converting nearly 25% of its weight into greenhouse gases and generating environmental problems. For this reason, it is necessary to design processes aligned with the axes of sustainable development (environmental, social and economic) to promote valorization and diversification. <strong>Objective</strong>. To determine the effect of two pretreatments on the enzymatic saccharification of sugarcane bagasse for its subsequent conversion to bioethanol. <strong>Methodology.</strong> The production of enzymatic extracts by solid state fermentation (SSF) was carried out using sugarcane bagasse as support-substrate and autochthonous fungal strains as inoculum. For the enzymatic saccharification the sugarcane bagasse was pretreated with hydrogen peroxide and microwaves, for the hydrogen peroxide pretreatment the variables time (1, 3 and 6 h), ratio mL of peroxide per gram of bagasse (16. 6:1, 33.3:1 and 100:1), temperature (26, 50 and 70°C) and peroxide concentration (1, 3 and 5%); and for microwave pretreatment the variables microwave power (p30, p50 and p80) and time (5 and 10 min) were evaluated. For the enzymatic saccharification, enzymatic extracts produced by SSF and bagasse pretreated with hydrogen peroxide were used. Finally, fermentable sugars obtained from the enzymatic saccharification of sugarcane bagasse were used as a unique carbon source in alcoholic fermentation system. <strong>Results.</strong> The SSF results showed the presence of cellulase (2 U/g) and xylanase (61 U/g) activity. On the other hand, the results of pretreatment of sugarcane bagasse with hydrogen peroxide indicated that the best conditions were 100 mL of 3% hydrogen peroxide per gram of sugarcane bagasse at 50°C, while the best conditions of microwave pretreatment were 50p for 5 minutes. The enzymatic saccharification of sugarcane bagasse showed a maximum yield of reducing sugars when the sugarcane bagasse was pretreated with hydrogen peroxide, obtaining 0.41 g/g. Finally, the maximum ethanol concentration (4.32 g/L) was obtained after 48 hours of fermentation with commercial <em>Saccharomyces cerevisae</em>. <strong>Implications.</strong> The sugar agroindustry in Mexico is limited to the production of sucrose and ethanol, being necessary a sustainable productive diversification. <strong>Conclusions.</strong> The isolation of autochthonous fungal strains allowed the production of cellulases and xylanases by solid fermentation with adequate specificity to hydrolyze/saccharify pretreated sugarcane bagasse and its subsequent conversion to ethanol.</p>

Multistep Structural and Chemical Evaluation of Sugarcane Baggase, Pretreated With Alkali for Enhancing the Enzymatic Saccharification by Cellulase and Xylanase of the Pseudomonas sp. CVB-10 (MK443365) and Bacillus paramycoides T4 (MN370035) Mix-Culture System

The enzymatic saccharification of sugarcane bagasse was significantly increased by alkali pretreatment under mild conditions. The effectiveness of different concentrations of alkali and acid pretreatment of sugarcane bagasse for improving the enzymatic saccharification of lignocellulose has been evaluated. The sugarcane bagasse was characterized to contain 39.52% celluloses, 25.63% hemicelluloses, and 30.36% lignin. After that, sugarcane bagasse was pretreated with 5 and 10% of H2SO4 and NaOH at 121°C for 60 min. FTIR, XRD, and SEM analyses also showed significant molecular and surface structure changes of the sugarcane bagasse with 10% NaOH. Maximum saccharification was 489.5 mg/g from 10% NaOH pretreatment followed by 322.75, 301.25, and 276.6 mg/g from 10% H2SO4, 5% NaOH, and 5% H2SO4, respectively, which were 55.1, 32.0, 27.1, and 20.6 times higher than the that of the control. Cellulase and xylanase produced by Pseudomonas sp. CVB-10 (MK443365) and Bacillus paramycoides T4 (MN370035) were used to hydrolyze the pretreated bagasse, and the optimal condition was determined to be 30 h of the enzymatic reaction with the 3:1 ratio of enzymes under the temperature of 55°C, pH 5.0, and substrate concentration of 3%, leading to celluloses and hemicelluloses conversion in the enzymatic hydrolysis/saccharification that is more proficient.

Intensification of sugar production by using Tween 80 to enhance metal-salt catalyzed pretreatment and enzymatic hydrolysis of sugarcane bagasse

In this study, different metal-salt catalyzed pretreatment was presented to disorganize the obstinate structure by eliminating the majority of hemicellulose, fractional of lignin, and improve the enzymatic saccharification of sugarcane bagasse. With the accession of Tween 80 during enzymolysis, all metal-salt pretreated substrates presented higher glucose yields, especially for CuCl2. Furthermore, Tween 80 was added to the pretreatment, enhancing the elimination of hemicellulose and lignin, decreasing the degradation of sugars to inhibitors, and presenting superior performance on improving glucose yield. In addition, the maximum glucose yield of 88.0% was achieved by using Tween 80 concomitantly with AlCl3 pretreatment and enzymolysis. It was also found that adding Tween 80 during pretreatment or/and enzymolysis after 24 h could liberate the similar glucose without Tween 80 after 72 h. However, the enhancement of Tween 80 at 6 h was higher than that at 72 h.

Sodium hydroxide catalytic ethanol pretreatment and surfactant on the enzymatic saccharification of sugarcane bagasse

The effect of NaOH catalytic ethanol pretreatment under various temperatures (130–180 °C) and time (15–90 min) on the chemical composition and enzymatic saccharification of sugarcane bagasse was investigated in this study. The results showed that NaOH catalytic ethanol pretreatment assisted delignification and the reservation of cellulose and hemicellulose. When sugarcane bagasse was pretreated at 180 °C for 30 min, a substantial glucose yield of 91.6% was obtained after hydrolysis for 72 h, representing 94.6% of glucose in pretreated residue. This yield was promoted with respect to the compositional change and surface alteration of pretreated substrate. With the supplement of Tween 80, the enzyme usage would be saved by 50% and the enzymolysis time could be shortened to 24 h while obtaining comparable glucose yield. This study provided an economical feasible and gradual process for the generation of glucose, which was followed by fermentation and conversion to platform chemicals.

Saccharification of pretreated sugarcane bagasse using enzymes solution from Pycnoporus sanguineus MCA 16 and cellulosic ethanol production

Pycnoporus sanguineus MCA 16 was cultivated by solid state fermentation on lignocellulosic residues, at 40 °C. The highest endoglucanase, exoglucanase, β-glucosidase, xylanase, β-xylosidase and laccase activities (200, 29.1, 52.1, 44.2, 1.81 and 22.04 U g−1, respectively) were obtained when using the mixture of wheat bran and soybean meal (1:1 w/w) as substrates, at 96 h of cultivation. Peroxidases highest activities were observed at 48 h (14.61 and 10.02 U g−1 for manganese and lignin peroxidase, respectively). Enzymatic saccharification of sugarcane bagasse submitted to hydrothermal alkaline pretreatment provided glucose at 7.32 g L−1 when using solid load of 13.5% (dry basis), 288.3 total units of endoglucanase/g of cellulose, 130 h and 57 °C. Ligninases present in the enzymatic solution provided a reduction of 82.3% in the concentration of total phenolic compounds during saccharification. The hydrolysate was used for ethanol production by Saccharomyces cerevisiae CAT-1 and a yield of 73.5% was obtained.

The sequential Fenton oxidation and sulfomethylation pretreatment for alleviating the negative effects of lignin in enzymatic saccharification of sugarcane bagasse

The sugarcane bagasse (SCB) was pretreated by the sequential Fenton oxidation and sulfomethylation pretreatment (FSP) for reducing the lignin inhibition in enzymatic saccharification. The FSP showed the delignification of 67.76% and the glucan retention in pretreated solid of 97.81%. Compared with sulfomethylation pretreated SCB (SP-SCB), the lignin surface coverage and surface hydrophobicity of FSP-SCB decreased by 1.84 and 4.84 times, respectively, led to enzymatic accessibility increased by 20%. Using the cellulase loading of 20 FPU/g glucan, the 72 h yields of glucose and xylose were 76.24% and 64.83%, respectively, which was 1.3–2.0 times higher than that of sulfomethylation treated SCB alone. Fenton oxidative reaction as a pre-step will help sulfomethyl group to easily and more introduce on aromatic ring, thereby accelerating the delignification.

Comparison of Fenton and bismuth ferrite Fenton-like pretreatments of sugarcane bagasse to enhance enzymatic saccharification

This study compared enzymatic saccharification of sugarcane bagasse (SCB) after application of two different pretreatment methods, Fenton pretreatment (FP) and BiFeO3 Fenton-like pretreatment (BFP). The composition, morphology and structural properties of SCB with different pretreatments were analyzed. Results showed that, after BFP, the yield of reducing sugar of SCB under enzymatic saccharification for 72 h was 25.8%, and the sugar conversion rate was 36.6%, which were 2.2 and 2.4-fold those of the FP, respectively. Moreover, the removal of hemicellulose and delignification in the BFP was more severe than that in the FP. The determination of hydroxyl radical (OH) in the two different Fenton processes revealed that the OH generated in the BiFeO3 Fenton-like system was higher in concentration and longer in action time than that in the Fenton system, which was likely key to the stronger effect of BFP than FP on the enzymatic saccharification of SCB.

Enhancing enzymatic saccharification of sugarcane bagasse by combinatorial pretreatment and Tween 80

BackgroundThe recalcitrant structure of lignocellulosic biomass made it challenging for their bioconversion into biofuels and biochemicals. Pretreatment was required to deconstruct the intact structure by the removal of hemicellulose/lignin, improving the cellulose accessibility of enzyme. Combinatorial pretreatments with liquid hot water/H2SO4 and ethanol/NaOH of sugarcane bagasse were developed to improve enzymatic hydrolysis under mild conditions.ResultsAfter one-step 60% ethanol containing 0.5% NaOH pretreatment with solid to liquid ratio of 1/10, the glucose yield after hydrolysis for 72 h with enzyme dosage of 20 FPU/g substrate was enhanced by 41% and 205% compared to that of NaOH or 60% ethanol pretreated solids, respectively. This improvement was correlated with the removal of hemicellulose and lignin. However, using combinatorial pretreatments with 1% H2SO4 followed by 60% ethanol containing 0.5% NaOH, the highest glucose yield with Tween 80 reached 76%, representing 84.5% of theoretical glucose in pretreated substrate. While retaining similar glucose yield, the addition of Tween 80 capacitated either a reduction of enzyme loading by 50% or shortening hydrolysis time to 24 h. However, the enhancement with the addition of Tween 80 decreased as hydrolysis time was extended.ConclusionsThis study demonstrated that a combinatorial pretreatment with 1% H2SO4 followed by 60% ethanol containing 0.5% NaOH had significant effects on improving the enzymatic hydrolysis of sugarcane bagasse. The addition of Tween 80 enabled reducing the enzyme loading or shortening the hydrolysis time. This study provided an economically feasible and mild process for the generation of glucose, which will be subsequently converted to bioethanol and biochemicals.

Novel Pretreatment Methods to Improve Enzymatic Saccharification of Sugarcane Bagasse: A Report

A lot of recent research in the biomass sector is focusing on how to improve the efficiency of biomass resources. Pretreatment of biomass resources is a novel approach and has gained a lot of attention in the last decade. A review of modern methods and the latest technologies of enhancing the enzymatic saccharification of sugarcane bagasse are presented in this work. This paper looks at the very recent developments in this field. Use of such advanced methods as coupling ionic liquid pretreatment with supercritical fluids and ultrasound irradiation is taking us swiftly towards the ultimate goal which is achieving 100% yield at minimum cost with no adverse environmental effects. However, Optimum process conditions for these methods are yet to be discovered. There is a need to optimize the processes and learn completely about the reaction mechanism in order to shift from lab scale to pilot scale and ultimately to the industrial level. An effort is made to report the latest work and because of it, this paper contains about 95% citations from papers within the last five years. In the end, useful recommendations are given in the conclusion section.

Efficient pretreatment of sugarcane bagasse via dilute mixed alkali salts (K2CO3/K2SO3) soaking for enhancing its enzymatic saccharification

Abstract To decrease alkaline dosage and increase the enzymatic saccharification of sugarcane bagasse (SB), dilute mixed alkali salts soaking (0.5% K2CO3, 0.068% K2SO3) in an autoclave at 100–125 °C for 10–60 min was attempted to pretreat SB. The increased pretreatment severity at elevated temperatures resulted in the increase of delignification and enzymatic saccharification. It was found the optimum pretreatment temperature and pretreatment time were 120 °C for 40 min. Furthermore, FTIR, XRD and SEM characterized the porosity, morphology, and crystallinity changes of the pretreated SB samples. After the enzymatic in situ saccharification of 50 g/L SB in dilute K2CO3/K2SO3 (0.35% K2CO3, 0.048% K2SO3) media for 72 h, the reducing sugars and glucose could be obtained at 32.94 and 20.18 g/L, respectively. Finally, the SB-hydrolysates containing 20 g/L glucose were used for ethanol fermentation in the presence of dilute alkali salts. After 48 h, the ethanol yield was 0.394 g ethanol/g glucose, which represents 77.25% of the theoretical yield. In conclusion, an effective process about the biomass pretreatment, enzymatic saccharification and ethanol fermentation was successfully demonstrated in “one-pot” media containing low loading of alkali salts K2CO3/K2SO3.

Enhanced enzymatic saccharification of sugarcane bagasse pretreated by sodium methoxide with glycerol

Sodium methoxide (CH3ONa) with glycerol pretreatment (CWGP) was performed to improve the enzymatic digestibility of sugarcane bagasse (SCB). Response surface methodology was utilized to optimize the CWGP parameters for pretreating SCB from the perspective of total fermentable sugar yield (TFSY) and total fermentable sugar concentration (TFSC). Under the optimal CWGP conditions, 0.5666g/g of TFSY (0.82% CH3ONa, 1.11h, 150°C) and 17.75g/L of TFSC (0.87% CH3ONa, 1.38h, 149.27°C) were achieved, corresponding to delignification of 79.05% and 79.34%, respectively. Compared the pretreatment using glycerol or CH3ONa alone, the CWGP has significant synergies to enhance the enzymatic efficiency of SCB. The physical and chemical characteristics of untreated and pretreated SCBs were analyzed using FT-IR, XRD, and SEM, and the results suggest that CWGP significantly increased the susceptibility of the substrates to enzymatic digestibility. Ultimately, CWGP might be a prospective candidate for the pretreatment process of enzyme-based lignocellulosic biorefineries.

Enhanced enzymatic saccharification of sugarcane bagasse pretreated by combining O2 and NaOH

Sugarcane bagasse pretreated by combining O2 and NaOH with different variables was conducted to improve its enzymatic digestibility and sugar recovery, and the results were compared with sole NaOH pretreatment. Lignin removal for O2–NaOH pretreatment was around 10% higher than that for sole NaOH pretreatment under the same conditions, and O2–NaOH pretreatment resulted in higher glucan recovery in the solid remain. Subsequently, O2–NaOH pretreated sugarcane bagasse presented more efficient enzymatic digestibility than sole NaOH pretreatment. Under the moderate pretreatment conditions of combining 1% NaOH and 0.5MPa O2 at 80°C for 120min, a high glucan conversion of 95% was achieved after 48h enzymatic hydrolysis. Coupled with the operations of pretreatment and enzymatic hydrolysis, an admirable total sugar recovery of 89% (glucose recovery of 93% and xylose recovery of 84%) was obtained. The susceptibility of the substrates to enzymatic digestibility was explained by their physical and chemical characteristics.

Cholinium ionic liquid/cosolvent pretreatment for enhancing enzymatic saccharification of sugarcane bagasse

In order to reduce the amount of choline acetate ([Cho][OAc]), (a less expensive, more biodegradable and biocompatible ionic liquids) used in the pretreatment of sugarcane bagasse, [Cho][OAc] combined with organic solvents pretreatments were attempted. The glucose yields after a 72-h enzymatic saccharification of sugarcane bagasse pretreated with [Cho][OAc] combined with organic cosolvents dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), or ethylene glycol (EG) at a weight ratio of 1:1 keeping at 130°C for 180min were approximately equal to those from the bagasse treated with [Cho][OAc] alone. The result indicated that the combination use of the cosolvents made it possible to reduce 50% of amount used of [Cho][OAc]. The enhancement effect of the [Cho][OAc]/cosolvent pretreatment on enzymatic saccharification could be attributed to an equal or greater effect on removal of hemicelluloes and lignin compared to the [Cho][OAc] treatment alone, although a lower effect on reduction in cellulose: which was supported by componential and X-ray diffraction (XRD) analyses. The bagasse pretreated with [Cho][OAc]/DMSO (1:1w/w) used in simultaneous saccharification and fermentation using Saccharomyces cerevisiae BA11, and ethanol was produced with a corresponding to conversion ratio of 69.9%.

Successive pretreatment and enzymatic saccharification of sugarcane bagasse in a packed bed flow-through column reactor aiming to support biorefineries

A packed bed flow-through column reactor (PBFTCR) was used for pretreatment and subsequent enzymatic hydrolysis of sugarcane bagasse (SCB). Alkaline pretreatment was performed at 70°C for 4h with fresh 0.3M NaOH solution or with liquor recycled from a previous pretreatment batch. Scheffersomyces stipitis NRRL-Y7124 was used for fermentation of sugars released after enzymatic hydrolysis (20FPUg−1 of dry SCB). The highest results for lignin removal were 61% and 52%, respectively, observed when using fresh NaOH or the first reuse of the liquor. About 50% of cellulosic and 57% of hemicellulosic fractions of pretreated SCBs were enzymatically hydrolyzed and the maximum ethanol production was 23.4gL−1 (ethanol yield of 0.4gpgs−1), with near complete consumption of both pentoses and hexoses present in the hydrolysate during the fermentation. PBFTCR as a new alternative for SCB-biorefineries is presented, mainly considering its simple configuration and efficiency for operating with a high solid:liquid ratio.

Comparison of choline acetate ionic liquid pretreatment with various pretreatments for enhancing the enzymatic saccharification of sugarcane bagasse

In this study, ionic liquid (IL) pretreatment using choline acetate ([Cho][OAc]), which is a completely bioderived IL, for enhancing the enzymatic saccharification of lignocellulose was investigated. To evaluate [Cho][OAc] IL pretreatment, its effects on sugarcane bagasse composition, its subsequent enzymatic saccharification, and the energy profit ratio (EPR) were compared with those of various pretreatments, such as comminution, microwave irradiation, and alkaline treatment. After 72h of enzymatic saccharification using bagasse pretreated with [Cho][OAc] at 110°C for 360min, 0.355g of glucose per 1g of raw bagasse was obtained (i.e., 98.7% of the cellulose content of the pretreated bagasse was converted into glucose), and maximum EPR was achieved in these pretreatment conditions.

Effect of Ionic Liquid Pretreatment on the Enzymatic Saccharification of Sugarcane Bagasse

onic liquid, 1-n-butyl-3-methylimidazolium chloride ([C4mi Cl) was used to pretreat sugarcane bagasse (SCB), followed by regeneration of SCB by addition of deionized water. The regenerated SCB exhibited enhancement in enzymatic saccharification with an average 3.1-fold enhancement in yield of reducing sugar produced compared to untreated SCB in the kinetic study. The maximum yield of glucose and reducing sugar produced were 2.6% and 4.3% respectively for untreated SCB, whereas the maximum yield of glucose and reducing sugar produced were more significant with value of 7.2% and 16.6% respectively for IL-pretreated SCB. This paper suggested that the IL-pretreatment of SCB could be a useful pretreatment method to increase the yield of sugars produced in enzymatic saccharification.

Enhancement of enzymatic saccharification of sugarcane bagasse by liquid hot water pretreatment

Lignocellulosic biomass can be utilized to produce promising biofuels. In this study, liquid hot water pretreatments were performed to break the intricate structure of sugarcane bagasse, which resists the enzyme accessibility to cellulose. The effects of temperatures and times on the hemicellulose degradation (including the yields of pentoses and hexoses, the proportion of monomers and oligosaccharides, as well as limited inhibitors) and cellulose enzymatic digestibility were evaluated. The results indicated that the maximum xylose yields (combined 3.85 g xylose and 13.21 g xylo-oligosaccharides per 100 g raw material) in prehydrolyzate liquid were obtained at 180 °C and 30 min. Due to the effective removal of hemicellulose, the maximum glucose yield in enzyme hydrolyzate reached 37.27 g per 100 g raw material, representing 90.13% of glucose in the sugarcane bagasse. The maximal total sugars yield (combined prehydrolyzate and enzymatic hydrolyzate) were 53.65 g based on 100 g raw material.

Association of wet disk milling and ozonolysis as pretreatment for enzymatic saccharification of sugarcane bagasse and straw

Ozonolysis was studied separately and in combination with wet disk milling (WDM) for the pretreatment of sugarcane bagasse and straw, with the aim of improving their enzymatic saccharification. The glucose yields for ozonolysis followed by WDM were 89.7% for bagasse and 63.1% for straw, whereas the use of WDM followed by ozonolysis resulted in glucose yields of 81.1% for bagasse and 92.4% for straw, with shorter WDM time. This last procedure allowed a substantial decrease in energy consumption in comparison to the use of WDM alone or of ozonolysis followed by WDM. Higher overall saccharification yields with shorter milling times were observed when ozonolysis was carried out before WDM. This effect might be related to the higher specific surface area. Additionally, a finer morphology was observed by the association of the two treatments in comparison to the sole use of ozonolysis or WDM.

Enzymatic saccharification of sugarcane bagasse by N-methylmorpholine-N-oxide-tolerant cellulase from a newly isolated Galactomyces sp. CCZU11-1

Based on the enrichment culture strategy, a novel N-methylmorpholine-N-oxide (NMMO)-tolerant cellulase-producing strain Galactomyces sp. CCZU11-1 was isolated from soil samples. After the optimization of culture condition, the highest FPA (13.4U/mL) and CMCase (24.5U/mL) were obtained. In both culture and reaction media containing NMMO 25% (w/v), the cellulase from Galactomyces sp. CCZU11-1 still had good activity. Furthermore, high saccharification rate was obtained in aqueous-NMMO media. Moreover, the fermentability of the hydrolyzates, obtained after enzymatic in situ saccharification of the NMMO-pretreated sugarcane bagasse, was evaluated using Saccharomyce scerevisiae. In conclusion, Galactomyces sp. CCZU11-1 is a promising candidate as high NMMO-tolerant cellulase producer and has potential application in future.