Batch and multi-step fed-batch enzymatic saccharification of Formiline-pretreated sugarcane bagasse at high solid loadings for high sugar and ethanol titers

Advances and Challenges in Biocatalysts Application for High Solid-Loading of Biomass for 2nd Generation Bio-Ethanol Production

Growth in population and thereby increased industrialization to meet its requirement, has elevated significantly the demand for energy resources. Depletion of fossil fuel and environmental sustainability issues encouraged the exploration of alternative renewable eco-friendly fuel resources. Among major alternative fuels, bio-ethanol produced from lignocellulosic biomass is the most popular one. Lignocellulosic biomass is the most abundant renewable resource which is ubiquitous on our planet. All the plant biomass is lignocellulosic which is composed of cellulose, hemicellulose and lignin, intricately linked to each other. Filamentous fungi are known to secrete a plethora of biomass hydrolyzing enzymes. Mostly these enzymes are inducible, hence the fungi secrete them economically which causes challenges in their hyperproduction. Biomass’s complicated structure also throws challenges for which pre-treatments of biomass are necessary to make the biomass amorphous to be accessible for the enzymes to act on it. The enzymatic hydrolysis of biomass is the most sustainable way for fermentable sugar generation to convert into ethanol. To have sufficient ethanol concentration in the broth for efficient distillation, high solid loading ~<20% of biomass is desirable and is the crux of the whole technology. High solid loading offers several benefits including a high concentration of sugars in broth, low equipment sizing, saving cost on infrastructure, etc. Along with the benefits, several challenges also emerged simultaneously, like issues of mass transfer, low reaction rate due to water constrains in, high inhibitor concentration, non-productive binding of enzyme lignin, etc. This article will give an insight into the challenges for cellulase action on cellulosic biomass at a high solid loading of biomass and its probable solutions.

Cellulase Addition and Pre-hydrolysis Effect of High Solid Fed-Batch Simultaneous Saccharification and Ethanol Fermentation from a Combined Pretreated Oil Palm Trunk

In the current study, alkaline hydrogen peroxide pretreated oil palm trunk fibers were subjected to ethanol production via simultaneous saccharification and fermentation (SSF). The effect of high substrate loading, enzyme and substrate feeding strategy, and influence of a pre-hydrolysis step in SSF was studied to scale up ethanol production. In the enzyme feeding strategy, the addition of an enzyme at the start of fed-batch SSF significantly (p < 0.05) increased ethanol concentration to 51.05 g/L, ethanol productivity (Q_P ) to 0.61 g/L·h, and ethanol yield (Y _P/S) to 0.31 g/g, with a theoretical ethanol yield of 60.65%. Furthermore, the initial velocity of the enzyme (V ₀) in the first 8 h was 2.27 (g/h) with a glucose concentration of 18.17 g/L. On the other hand, the substrate feeding strategy and pre-hydrolysis simultaneous saccharification and fermentation (PSSF) process were studied in a 1 L fermenter. PSSF in fed batch with 10 and 20% (w/v) significantly improved enzyme hydrolysis, circumvent the problems of high viscosity, reduced overall fermentation time, and gave the highest ethanol concentration of 51.66 g/L, ethanol productivity (Q_P ) of 0.72 g/L·h, ethanol yield (Y _P/S) of 0.31 g/g, and theoretical ethanol yield of 60.66%. In addition, PSSF with 10 and 20% significantly increased the initial velocity of the enzyme (V ₀) to 4.64 and 4.40 (g/h) and glucose concentration to 37.14 and 35.27 g/L, respectively. This result indicated that ethanol production by PSSF along with substrate feeding could enhance ethanol production efficiently.

Emerging trends in high-solids enzymatic saccharification of lignocellulosic feedstocks for developing an efficient and industrially deployable sugar platform

For the techno-commercial success of any lignocellulosic biorefinery, the cost-effective production of fermentable sugars for the manufacturing of bio-based products is indispensable. High-solids enzymatic saccharification (HSES) is a straightforward approach to develop an industrially deployable sugar platform. Economic incentives such as reduced capital and operational expenditure along with environmental benefits in the form of reduced effluent discharge makes this strategy more lucrative for exploitation. However, HSES suffers from the drawback of non-linear and disproportionate sugar yields with increased substrate loadings. To overcome this bottleneck, researchers tend to perform HSES at high enzyme loadings. Nonetheless, the production costs of cellulases are one of the key contributors that impair the entire process economics. This review highlights the relentless efforts made globally to attain a high-titer of sugars and their fermentation products by performing efficient HSES at low cellulase loadings. In this context, technical innovations such as advancements in new pretreatment strategies, next-generation cellulase cocktails, additives, accessory enzymes, novel reactor concepts and enzyme recycling studies are especially showcased. This review further covers new insights, learnings and prospects in the area of lignocellulosic bioprocessing.

Potential for reduced water consumption in biorefining of lignocellulosic biomass to bioethanol and biogas

Increasing ethanol demand and public concerns about environmental protection promote the production of lignocellulosic bioethanol. Compared to that of starch- and sugar-based bioethanol production, the production of lignocellulosic bioethanol is water-intensive. A large amount of water is consumed during pretreatment, detoxification, saccharification, and fermentation. Water is a limited resource, and very high water consumption limits the industrial production of lignocellulosic bioethanol and decreases its environmental feasibility. In this review, we focused on the potential for reducing water consumption during the production of lignocellulosic bioethanol by performing pretreatment and fermentation at high solid loading, omitting water washing after pretreatment, and recycling wastewater by integrating bioethanol production and anaerobic digestion. In addition, the feasibility of these approaches and their research progress were discussed. This comprehensive review is expected to draw attention to water competition between bioethanol production and human use.

Ethanol Production from High Solid Loading of Rice Straw by Simultaneous Saccharification and Fermentation in a Non-Conventional Reactor

Simultaneous saccharification and fermentation (SSF) at high solid loading is a potential approach to improve the economic feasibility of cellulosic ethanol. In this study, SSF using high loading of rice straw was assessed using a vertical ball mill reactor. First, the conditions of temperature and number of glass spheres were optimized at 8% (w/v) initial solids (41.5 °C, 18 spheres). Then, assays were carried out at higher solid loadings (16% and 24% w/v). At 8% or 16% solids, the fermentation efficiency was similar (ηF~75%), but the ethanol volumetric productivity (QP) reduced from 1.50 to 1.14 g/L.h. By increasing the solids to 24%, the process was strongly affected (ηF = 40% and QP = 0.7 g/L.h). To overcome this drawback, three different feeding profiles of 24% pre-treated rice straw were investigated. Gradual feeding of the substrate (initial load of 16% with additions of 4% at 10 and 24 h) and an inoculum level of 3 g/L resulted in a high ethanol titer (52.3 g/L) with QP of 1.1 g/L.h and ηF of 67%. These findings demonstrated that using a suitable fed-batch feeding strategy helps to overcome the limitations of SSF in batch mode caused by the use of high solid content.

Constraints and advances in high-solids enzymatic hydrolysis of lignocellulosic biomass: a critical review

The industrial production of sugar syrups from lignocellulosic materials requires the conduction of the enzymatic hydrolysis step at high-solids loadings (i.e., with over 15% solids [w/w] in the reaction mixture). Such conditions result in sugar syrups with increased concentrations and in improvements in both capital and operational costs, making the process more economically feasible. However, this approach still poses several technical hindrances that impact the process efficiency, known as the "high-solids effect" (i.e., the decrease in glucan conversion yields as solids load increases). The purpose of this review was to present the findings on the main limitations and advances in high-solids enzymatic hydrolysis in an updated and comprehensive manner. The causes for the rheological limitations at the onset of the high-solids operation as well as those influencing the "high-solids effect" will be discussed. The subject of water constraint, which results in a highly viscous system and impairs mixing, and by extension, mass and heat transfer, will be analyzed under the perspective of the limitations imposed to the action of the cellulolytic enzymes. The "high-solids effect" will be further discussed vis-à-vis enzymes end-product inhibition and the inhibitory effect of compounds formed during the biomass pretreatment as well as the enzymes' unproductive adsorption to lignin. This review also presents the scientific and technological advances being introduced to lessen high-solids hydrolysis hindrances, such as the development of more efficient enzyme formulations, biomass and enzyme feeding strategies, reactor and impeller designs as well as process strategies to alleviate the end-product inhibition. We surveyed the academic literature in the form of scientific papers as well as patents to showcase the efforts on technological development and industrial implementation of the use of lignocellulosic materials as renewable feedstocks. Using a critical approach, we expect that this review will aid in the identification of areas with higher demand for scientific and technological efforts.

Enhancement of high-solids enzymatic hydrolysis efficiency of alkali pretreated sugarcane bagasse at low cellulase dosage by fed-batch strategy based on optimized accessory enzymes and additives

Obtaining higher amount of final sugars with low cellulase dosage has great economic benefits for the industrial biorefinery of lignocellulosic biomass. The optimization of accessory enzymes and additives were performed using single factor and orthogonal experiment firstly, after that, fed-batch strategy was applied to enhance the high-solids enzymatic hydrolysis efficiency of alkali pretreated sugarcane bagasse (SCB). A novel enzymatic hydrolysis procedure with 22% (w/v) substrate content and cellulase dosage of only 4 FPU/g dry biomass (DM) was developed, after digested for 48 h, the achieved glucose titer, yield and productivity were 122 g/L, 80% and 2.54 g L^-1 h^-1, respectively. Results obtained in this study indicated a potential finding for the industrial application of lignocellulosic biomass.

Enhanced enzymatic hydrolysis of cellulose from waste paper fibers by cationic polymers addition

Cationic polymers (cationic polyacrylamide (CPAM), polyethyleneimine (PEI) or cationic starch (CS)) were used to enhance the enzymatic hydrolysis of waste paper fibers (WPFs) at 15% (w/w) solids concentration. Results showed that 0.05 g/L PEI, CPAM and CS resulted in 72.5%, 65.9% and 59.7% conversion of WPFs, increased by 15.4%, 8.8% and 2.6%, respectively, compared with control (57.1%). PEI was shown to have a larger effect than CPAM and CS, and generate a total sugar concentration of 73.9 g/L. Improvement in hydrolysis with cationic polymer addition is attributed to increased cellulase adsorption on cellulose through electrostatic attraction, rather than enhancement of cellulase activity. A patching/ bridging mechanism of cationic polymer enhancement of cellulose adsorption in cellulose is hypothesized. PEI exhibited maximum cellulose binding for polymers examined and appears to promote binding through a patching mechanism. CPAM and CS adsorbed a relatively low cellulase through bridging mechanism. In addition, enzyme loading could be reduced by addition of cationic polymers to obtain the same glucose yield, especially when PEI was used.

Comparison of One-Stage Batch and Fed-Batch Enzymatic Hydrolysis of Pretreated Hardwood for the Production of Biosugar

Fed-batch method has shown a great promise in debottlenecking the high-solid enzymatic hydrolysis for the commercialization of cellulosic biosugar conversion for biofuel/biochemical production. To further improve enzymatic hydrolysis efficiency at high solid loading, fed-batch methods of green liquor-pretreated hardwood were performed to evaluate their effects on sugar recovery by comparing with one-stage batch method in this study. Among all the explored conditions, the fed-batch at 15% consistency gave higher sugar recovery on green liquor-pretreated hardwood compared to that of one-stage batch. By using general linear model analysis, the percentage of enzymatic sugar recovery in fed-batch consistency method (increasing consistency from the initial 10.7 to 15% at intervals of 24 and 48 h) was higher than that of batch hydrolysis at higher density of 15% consistency. Under that best fed-batch condition, the total sugar recovery of pretreated hardwood in enzymatic hydrolysate reached approximately 48.41% at Cellic® enzyme loading of 5 filter-paper unit (FPU)/g and 58.83% at Cellic® enzyme loading of 10 FPU/g with a hydrolysis time of 96 h.

Enzyme recycle and fed-batch addition for high-productivity soybean flour processing to produce enriched soy protein and concentrated hydrolysate of fermentable sugars

Despite having high protein and carbohydrate, soybean flour utilization is limited to partial replacement of animal feed to date. Enzymatic process can be exploited to increase its value by enriching protein content and separating carbohydrate for utilization as fermentation feedstock. Enzyme hydrolysis with fed-batch and recycle designs were evaluated here for achieving this goal with high productivities. Fed-batch process improved carbohydrate conversion, particularly at high substrate loadings of 250-375g/L. In recycle process, hydrolysate retained a significant portion of the limiting enzyme α-galactosidase to accelerate carbohydrate monomerization rate. At single-pass retention time of 6h and recycle rate of 62.5%, reducing sugar concentration reached up to 120g/L using 4ml/g enzyme. When compared with batch and fed-batch processes, the recycle process increased the volumetric productivity of reducing sugar by 36% (vs. fed-batch) to 57% (vs. batch) and that of protein product by 280% (vs. fed-batch) to 300% (vs. batch).

Evaluation of the solvent water effect on high solids saccharification of alkali-pretreated sugarcane bagasse

Solvent water is an essential factor for high solids enzymatic hydrolysis. To investigate its effect on substrate conversion efficiency in high solids hydrolysis of sugarcane bagasse (SCB), oleyl alcohol was used to partially substitute the solvent water. The results in batch hydrolysis tests in which diverse ratio of solvent water was replaced found that the majority of the substrate was insoluble. Then high solids fed-batch hydrolysis with the reaction solution mixed with solvent water and oleyl alcohol in the ratio of 3:1 (solids concentration correspond to 24% (w/v)) was carried out at the final real solids loading of 18% (w/v). The produced sugars were found to be less than pure water system, which indicated that water played a significant role in high solids hydrolysis process, and solids effect was related to the solvent water content.

Irradiation pretreatment facilitates the achievement of high total sugars concentration from lignocellulose biomass

This study evaluated the two hydrolysis strategies, involving one thermal and one dilute acid/enzymatic hydrolysis, to produce high xylose and glucose concentrations from lignocellulose assisted with irradiation pretreatment. Prior to hydrolysis, lignocellulose was pretreated by γ-irradiation at 800KGy. The merits of irradiation pretreatment on lignocellulose were contributed to size-reduced particle distributions and low shear rate of material, which allowed high biomass loadings up to 30-40%(w/v, equals to 23-29wt.%) for the consequent hydrolysis process. Results showed that hemicellulose fraction could achieve ∼84g/L of total sugars containing ∼55g/L xylose and ∼21g/L glucose through this two steps hydrolysis. Cellulose fraction would release ∼251g/L of total sugars consisting of ∼235g/L glucose and ∼16g/L xylose in the ultimate enzymatic hydrolysate. To the best of our knowledge, it was the first report of achieving 235g/L glucose in cellulose enzymatic hydrolysate derived from lignocellulose.

Production of high concentrated cellulosic ethanol by acetone/water oxidized pretreated beech wood

BACKGROUND

Lignocellulosic biomass is an abundant and inexpensive resource for biofuel production. Alongside its biotechnological conversion, pretreatment is essential to enable efficient enzymatic hydrolysis by making cellulose susceptible to cellulases. Wet oxidation of biomass, such as acetone/water oxidation, that employs hot acetone, water, and oxygen, has been found to be an attractive pretreatment method for removing lignin while producing less degradation products. The remaining enriched cellulose fraction has the potential to be utilized under high gravity enzymatic saccharification and fermentation processes for the cost-competing production of bioethanol.

RESULTS

Beech wood residual biomass was pretreated following an acetone/water oxidation process aiming at the production of high concentration of cellulosic ethanol. The effect of pressure, reaction time, temperature, and acetone-to-water ratio on the final composition of the pretreated samples was studied for the efficient utilization of the lignocellulosic feedstock. The optimal conditions were acetone/water ratio 1:1, 40 atm initial pressure of 40 vol% O₂ gas, and 64 atm at reaction temperature of 175 °C for 2 h incubation. The pretreated beech wood underwent an optimization step studying the effect of enzyme loading and solids content on the enzymatic liquefaction/saccharification prior to fermentation. In a custom designed free-fall mixer at 50 °C for either 6 or 12 h of prehydrolysis using an enzyme loading of 9 mg/g dry matter at 20 wt% initial solids content, high ethanol concentration of 75.9 g/L was obtained.

CONCLUSION

The optimization of the pretreatment process allowed the efficient utilization of beech wood residual biomass for the production of high concentrations of cellulosic ethanol, while obtaining lignin that can be upgraded towards high-added-value chemicals. The threshold of 4 wt% ethanol concentration that is required for the sustainable bioethanol production was surpassed almost twofold, underpinning the efficient conversion of biomass to ethanol and bio-based chemicals on behalf of the biorefinery concept.

Enzyme feeding strategies for better fed-batch enzymatic hydrolysis of empty fruit bunch

Lignin inhibitory becomes a major obstacle for enzymatic hydrolysis of empty fruit bunch conducted in high solid loading. Since current technology required high enzyme loading, surfactant application could not effectively used since it is only efficient in low enzyme loading. In addition, it will increase final operation cost. Hence, another method namely "proportional enzyme feeding" was investigated in this paper. In this method, enzyme was added to reactor proportionally to substrate addition, different from conventional method ("whole enzyme feeding") where whole enzyme was added prior to hydrolysis process started. Proportional enzyme feeding could increase enzymatic digestibility and glucose concentration up to 26% and 12% respectively, compared to whole enzyme feeding for hydrolysis duration more than 40h. If enzymatic hydrolysis was run less than 40h (25% solid loading), whole enzyme feeding is preferable.

Optimization of uncatalyzed steam explosion pretreatment of rapeseed straw for biofuel production

Rapeseed straw constitutes an agricultural residue with great potential as feedstock for ethanol production. In this work, uncatalyzed steam explosion was carried out as a pretreatment to increase the enzymatic digestibility of rapeseed straw. Experimental statistical design and response surface methodology were used to evaluate the influence of the temperature (185-215°C) and the process time (2.5-7.5min). According to the rotatable central composite design applied, 215°C and 7.5min were confirmed to be the optimal conditions, considering the maximization of enzymatic hydrolysis yield as optimization criterion. These conditions led to a maximum yield of 72.3%, equivalent to 81% of potential glucose in pretreated solid. Different configurations for bioethanol production from steam exploded rapeseed straw were investigated using the pretreated solid obtained under optimal conditions as a substrate. As a relevant result, concentrations of ethanol as high as 43.6g/L (5.5% by volume) were obtained as a consequence of using 20% (w/v) solid loading, equivalent to 12.4g ethanol/100g biomass.

Enzymatic hydrolysis of steam-exploded sugarcane bagasse using high total solids and low enzyme loadings

Hydrolysis of phosphoric acid-impregnated steam-treated sugarcane bagasse was pre-optimized using a face-centered central composite design in which the process variables were the substrate total solids (TS, %), agitation intensity (AI, rpm) and enzyme loading (EL, gg(-1)). Pretreatment was carried out at 180°C for 10min using cane bagasse with 50wt% moisture content containing 9.5mg of H3PO4 per gram of dry biomass. Hydrolyses were performed for 96h at 50°C using Cellic CTec2® and water-washed steam-treated substrates. The highest amount of fermentable sugars was obtained with 20wt% TS, producing 76.8gL(-1) of glucose equivalents, which corresponded to a total glucan conversion of 69.2wt% and to a theoretical net increase of 39% in ethanol production from the same sugarcane tonnage without considering the use of leaves, tops and the additional yields from C5 sugars.

Increased enzymatic hydrolysis of sugarcane bagasse from enzyme recycling

BACKGROUND

Development of efficient methods for production of renewable fuels from lignocellulosic biomass is necessary to maximize yields and reduce operating costs. One of the main challenges to industrial application of the lignocellulosic conversion process is the high costs of cellulolytic enzymes. Recycling of enzymes may present a potential solution to alleviate this problem. In the present study enzymes associated with the insoluble fraction were recycled after enzymatic hydrolysis of pretreated sugarcane bagasse, utilizing different processing conditions, enzyme loadings, and solid loadings.

RESULTS

It was found that the enzyme blend from Chrysoporthe cubensis and Penicillium pinophilum was efficient for enzymatic hydrolysis and that a significant portion of enzyme activity could be recovered upon recycling of the insoluble fraction. Enzyme productivity values (g glucose/mg enzyme protein) over all recycle periods were 2.4 and 3.7 for application of 15 and 30 FPU/g of glucan, representing an increase in excess of ten times that obtained in a batch process with the same enzyme blend and an even greater increase compared to commercial cellulase enzymes.

CONCLUSIONS

Contrary to what may be expected, increasing lignin concentrations throughout the recycle period did not negatively influence hydrolysis efficiency, but conversion efficiencies continuously improved. Recycling of the entire insoluble solids fraction was sufficient for recycling of adhered enzymes together with biomass, indicative of an effective method to increase enzyme productivity.

High ethanol fermentation performance of the dry dilute acid pretreated corn stover by an evolutionarily adapted Saccharomyces cerevisiae strain

Ethanol fermentation was investigated at the high solids content of the dry dilute sulfuric acid pretreated corn stover feedstock using an evolutionary adapted Saccharomyces cerevisiae DQ1 strain. The evolutionary adaptation was conducted by successively transferring the S. cerevisiae DQ1 cells into the inhibitors containing corn stover hydrolysate every 12h and finally a stable yeast strain was obtained after 65 days' continuous adaptation. The ethanol fermentation performance using the adapted strain was significantly improved with the high ethanol titer of 71.40 g/L and the high yield of 80.34% in the simultaneous saccharification and fermentation (SSF) at 30% solids content. No wastewater was generated from pretreatment to fermentation steps. The results were compared with the published cellulosic ethanol fermentation cases, and the obvious advantages of the present work were demonstrated not only at the high ethanol titer and yield, but also the significant reduction of wastewater generation and potential cost reduction.

Enzymatic hydrolysis of beech wood lignocellulose at high solid contents and its utilization as substrate for the production of biobutanol and dicarboxylic acids

The development of a cost-effective hydrolysis for crude cellulose is an essential part of biorefinery developments. To establish such high solid hydrolysis, a new solid state reactor with static mixing is used. However, concentrations >10% (w/w) cause a rate and yield reduction of enzymatic hydrolysis. By optimizing the synergetic activity of cellulolytic enzymes at solid concentrations of 9%, 17% and 23% (w/w) of crude Organosolv cellulose, glucose concentrations of 57, 113 and 152 g L(-1) are reached. However, the glucose yield decreases from 0.81 to 0.72 g g(-1) at 17% (w/w). Optimal conditions for hydrolysis scale-up under minimal enzyme addition are identified. As result, at 23% (w/w) crude cellulose the glucose yield increases from 0.29 to 0.49 g g(-1). As proof of its applicability, biobutanol, succinic and itaconic acid are produced with the crude hydrolysate. The potential of the substrate is proven e.g. by a high butanol yield of 0.33 g g(-1).

Robust enzymatic hydrolysis of Formiline-pretreated oil palm empty fruit bunches (EFB) for efficient conversion of polysaccharide to sugars and ethanol

Oil palm empty fruit bunch (EFB) was pretreated by Formiline process to overcome biomass recalcitrance and obtain hemicellulosic syrup and lignin. Higher formic acid concentration led to more lignin removal but also higher degree of cellulose formylation. Cellulose digestibility could be well recovered after deformylation with a small amount of lime. After digested by enzyme loading of 15 FPU+10 CBU/g solid for 48 h, the polysaccharide conversion could be over 90%. Simultaneous saccharification and fermentation (SSF) results demonstrated that ethanol concentration reached 83.6 g/L with approximate 85% of theoretic yield when performed at an initial dry solid consistency of 20%. A mass balance showed that via Formiline pretreatment 0.166 kg of ethanol could be produced from 1 kg of dry EFB with co-production of 0.14 kg of high-purity lignin and 5.26 kg hemicellulosic syrup containing 2.8% xylose. Formiline pretreatment thus can be employed as an entry for biorefining of EFB.

Current challenges in commercially producing biofuels from lignocellulosic biomass

Biofuels that are produced from biobased materials are a good alternative to petroleum based fuels. They offer several benefits to society and the environment. Producing second generation biofuels is even more challenging than producing first generation biofuels due the complexity of the biomass and issues related to producing, harvesting, and transporting less dense biomass to centralized biorefineries. In addition to this logistic challenge, other challenges with respect to processing steps in converting biomass to liquid transportation fuel like pretreatment, hydrolysis, microbial fermentation, and fuel separation still exist and are discussed in this review. The possible coproducts that could be produced in the biorefinery and their importance to reduce the processing cost of biofuel are discussed. About $1 billion was spent in the year 2012 by the government agencies in US to meet the mandate to replace 30% existing liquid transportation fuels by 2022 which is 36 billion gallons/year. Other countries in the world have set their own targets to replace petroleum fuel by biofuels. Because of the challenges listed in this review and lack of government policies to create the demand for biofuels, it may take more time for the lignocellulosic biofuels to hit the market place than previously projected.

Production and application of an enzyme blend from Chrysoporthe cubensis and Penicillium pinophilum with potential for hydrolysis of sugarcane bagasse

Blending of the enzyme extracts produced by different fungi can result in favorable synergetic enhancement of the enzyme blend with regards to the main cellulase activities, as well as the inclusion of accessory enzymes that may not be as abundant in enzyme extracts produced by predominantly cellulase producing fungi. The Chrysoporthe cubensis:Penicillium pinophilum 50:50 (v/v) blend produced herein presented good synergy, especially for FPase and endoglucanase activities which were 76% and 48% greater than theoretical, respectively. This enzyme blend was applied to sugarcane bagasse previously submitted to a simple alkali pretreatment. Glucan hydrolysis efficiency reached an excess of 60% and xylan conversion exceeded 90%. Increasing the hydrolysis temperature from 45 to 50°C also resulted in a 16-20% increase in conversion of both glucan and xylan fractions. The blended enzyme extract obtained therefore showed great potential for application in the lignocellulose hydrolysis process.