Gram Of Cellulose Research Articles

Homemade BIOPLASTICS (Biodegradable Plastic From Cassava Peel Waste) with Analysis of the Effect of Glycerol and Cellulose Ratio on Tensile Strength, Elongation, and Thickness

The massive use of plastic as food and non-food packaging does not cause a few problems. The accumulation of plastic waste can cause environmental pollution, both water and soil pollution, because plastic will be damaged and decomposed within 300 to 500 years. For this reason, environmentally friendly plastics are needed for conventional plastics which of course have characteristics that are not far inferior to conventional plastics such as flexible, lightweight, not easy to break, waterproof, not corrosive. Bioplastic is a type of plastic that can be degraded so it is not harmful to the environment. This paper aims to see the effect of the ratio of glycerol and cellulose on tensile strength, elongation, and thickness of bioplastics using cassava peel waste. This research uses cassava peel as the basic material for making starch which is then given a mixture of glycerol and cellulose to be used as bioplastics. Tensile strength and elongation tests were carried out using the zwick/roell Universal Testing Machine (UTM). While the thickness uses Mitutoyo's Thickness Gauge. The results obtained are thin plastic sheets made using 5 grams of starch with a mixture of cellulose (0.4; 0.6; 0.8) grams and glycerol (100%, 150%, 200%) ml which have been tested for mechanical properties. The best mechanical properties of the tensile strength of bioplastics were indicated by the sample coded C2G2 with a concentration of 1.5 ml of glycerol and 0.8 gram of cellulose with an average tensile strength of 7.4808 (N/mm2), while the highest elongation was shown in the sample coded C3G3. with a concentration of 2.0 ml of glycerol and 0.8 grams of cellulose with an average sample elongation value of 6.2448%, while the highest thickness determined in the sample coded C2G2, a concentration of 1.5 ml of glycerol and 0.6 grams of cellulose with a value of the average thickness is 269,066 (µm).

Gene-Expression Analysis of Human Fibroblasts Affected by 3D-Printed Carboxylated Nanocellulose Constructs.

Three-dimensional (3D) printing has emerged as a highly valuable tool to manufacture porous constructs. This has major advantages in, for example, tissue engineering, in which 3D scaffolds provide a microenvironment with adequate porosity for cell growth and migration as a simulation of tissue regeneration. In this study, we assessed the suitability of three cellulose nanofibrils (CNF) that were obtained through 2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO)-mediated oxidation. The CNFs were obtained by applying three levels of carboxylation, i.e., 2.5, 3.8, and 6.0 mmol sodium hypochlorite (NaClO) per gram of cellulose. The CNFs exhibited different nanofibrillation levels, affecting the corresponding viscosity and 3D printability of the CNF gels (0.6 wt%). The scaffolds were manufactured by micro-extrusion and the nanomechanical properties were assessed with nanoindentation. Importantly, fibroblasts were grown on the scaffolds and the expression levels of the marker genes, which are relevant for wound healing and proliferation, were assessed in order to reveal the effect of the 3D-scaffold microenvironment of the cells.

Sintesis Nitroselulosa Dari Serat Rami (Boechmerianivea) Menggunakan Trietilamin

Nitrocellulose is cellulose that is titrated into an ester polymer which can be used as a major component in several types of ammunition and explosives and other materials. Hemp (Boehmeria nivea) is a type of fiber plant that is rich in cellulose and thrives in Indonesia. Until now, the need for nitrocellulose in Indonesia is still imported, even though there is a lot of potential for cellulose that can be exploited, one of which is by synthesizing nitrocellulose from the hemp plant. One of the many uses of nitrocellulose derivatives, one of which is propellant. The propellant is the fuel or power source of a rocket engine. Nitrocellulose that can be used for propellants is nitrocellulose with levels between 11-13.3% nitrogen. This study aims to produce nitrocellulose in levels that meet the standards for making propellants. The study was carried out with a cellulose activation procedure using 20% ​​sodium hydroxide and 1 ml of triethylamine per gram of cellulose. Cellulose nitration was carried out using sulfuric acid and nitric acid with the composition of A (1: 1), B (2: 1) and C (3: 1) which were refluxed for 3 hours. Nitrogen determination was carried out using the Kjeldahl method. The results showed that from 3 samples A, B, and C, nitrogen levels were obtained respectively 12.62%, 13.23%, and 12.97%. This shows that the nitrocellulose from the hemp plant (Boehmeria nivea) can be used for propellants. 
 Keywords: Hemp, nitrocellulose, nitration, triethylamine, propellant

Nanocellulose recovery from domestic wastewater

Wastewater solids could be an attractive source of secondary raw cellulose, mainly originating from toilet paper. Cellulose can be recovered through sieving of raw wastewater, return sludge, or excess sludge. In particular, a large fraction of cellulose (13–15%) can be found in the excess sludge of the aerobic granular sludge produced by the Nereda® wastewater technology. A cellulose extraction method was developed during this study, allowing the recovery of a pulp with over 86 wt% purity. The wastewater derived cellulose fibres could be an excellent source for production of recovered cellulose nanocrystals (rCNC). Several pre-treatment steps needed in cellulose nanocrystals (CNC) production from wood pulp are already performed in the production of toilet paper. Here, the technical feasibility of such rCNC is studied. As reference materials, microcrystalline cellulose and toilet paper were also used. The rCNC were obtained by acid hydrolysis, with yields of ∼30 wt% (pulp basis). The wastewater-based material was rod-like, with high aspect ratio (10–14), crystallinity (62–68%), and chemical structure similar to commercial CNC. The yield of rCNC per gram of cellulose recovered from the influent was 22%, while for excess sludge cellulose it was less (4%). Bio-nanocomposites of rCNC and alginate were also investigated. At 50 vol% loading of rCNC, there was a 50% relative increase in stiffness (18 GPa) compared to matrix (12 GPa). The characterization of rCNC and positive impact in composite materials confirms a suitable quality of wastewater derived CNC. Ultimately, the nanocellulose is a tangible example that recovery of high-end products from wastewater is possible, in line with a circular economy.

Influence of post-oxidation reactions on the physicochemical properties of TEMPO-oxidized cellulose nanofibers before and after amidation

During TEMPO-mediated oxidation of cellulose, primary alcohols on the surface ideally undergo oxidation to carboxylic acids. However, it is well known that some of these hydroxyl groups partially oxidize to aldehydes. To increase the degree of oxidation (DO) of nanocellulose, these unreacted aldehydes can be fully oxidized to carboxylic acids employing various strategies. We performed post-oxidation reactions using NaClO2, on TEMPO-Oxidized Cellulose Nanofibers (TOCN) to investigate how this reaction influenced the physicochemical properties of nanocelulose before and after amidation with octadecylamine (ODA). We report on an increase in the content of carboxylate in TOCN (1.57 mmol/g of cellulose) up 40% after post-oxidation with NaClO2 (2.20 mmol/g of cellulose). These results indicate that with TEMPO-mediated oxidation, 1.57 mmol of hydroxymethyl groups per gram of cellulose were completely oxidized to –COOH, and after treatment with NaClO2, about 0.63 mmol of partially-oxidized alcohols (aldehyde groups) on TOCN were fully oxidized to COOH. Theoretical HLB values of 11.04 and 11.13 for TOCN and post-oxidized TOCN (TOCN-P) indicate that these materials behave as hydrophilic o/w surfactants or emulsifying agents with high affinity for polar phases. They also form highly stable dispersions in water due to an increased charge density as indicated by ζ-potential values of -56 mV for TOCN and -64 mV for TOCN-P. Low contact angles (CA) of 24o and 21o for TOCN and TOCN-P films confirm their hydrophilic nature. After amidation reactions with ODA, we observe a 73% and an 82% decrease in carboxylate content for TOCN and TOCN-P. These values can be related with the degree of coupling (DC) leading to amide formation on the nanocellulose surface, i.e., about 1.14 and 1.80 mmol of amide units were coupled per gram of cellulose on TOCN-ODA and TOCN-P-ODA. ζ-potential values decreased 34% and 52% after amidation, to -37 mV and -31 mV for TOCN-ODA and TOCN-P-ODA, indicating a low stability of these materials in water dispersions. Theoretical HLB values 125o) films illustrate the effect of octadecylamine alkyl chains on the hydrophobic properties of the nanocellulose’s surface. Thermal analysis indicates that amidation reactions can effectively shield in the nanocellulose’s surface from thermal degradation from by increasing the decomposition temperature from around 296 °C for “naked” TOCN to > 330 °C for the “protected” amidated nanocellulose.

Ethanol production by simultaneous saccharification and cofermentation of pretreated corn stalk.

The recalcitrance of lignocellulosic biomass is a major factor limiting its conversion into biofuels. Therefore, in this study, we pretreated corn stalk with 2% Na2 CO3 and 2% H2 O2 for time 70 min at 130°C using a corn stalk to liquid ratio of 1:10. The fermentation broth from multicopy Saccharomyces cerevisiae strains engineered for lignocellulase synthesis was used to enzymatically hydrolyze the pretreated corn stalk. The highest monosaccharide yield (102 mmol/L) was obtained using 15 IU endocellulase, 10 IU exocellulase, and 15 IU β-glucosidase per gram of cellulose and 20 IU xylanase per gram of hemicellulose. Subsequently, the high-efficiency ethanol-producing S. cerevisiae strain WXY12, which can produce ethanol from glucose and xylose simultaneously, was added to the fermentation system. The entire process involved ethanol production through simultaneous saccharification and fermentation (SSF). Optimization of the fermentation conditions (yeast powder as a nitrogen source, temperature of 30°C, MgSO4 as a metal ion inducer, rotation speed of 180 rpm, solid-liquid ratio of 1:8, and inoculation amount of 2%) resulted in an ethanol output of 46.87 g/L and a theoretical conversion rate of 27.4%. The results of this study improved corn stalk utilization, reduced hydrolysis costs, and generated high ethanol yields.

Highly efficient single-step pretreatment to remove lignin and hemicellulose from softwood

The use of lignocellulosic softwood residues as feedstock for the production of bioethanol and other value-added chemical products has been limited by its high recalcitrance. Alkaline or organosolvent pretreatments have been used to remove recalcitrance in softwoods. Although these methods partially remove lignin and hemicellulose, they also result in low glucose recovery. In the first case, there is low cellulose hydrolizability, and in the second, there is a loss of cellulose. This study evaluated both methods combined into one step: alkaline hydrolysis of the biomass in the presence of an organosolvent. Different conditions of temperature and residence times were assayed. The efficiency of these conditions was quantified as the percentage of lignin and hemicellulose removed from the biomass without loss of cellulose. The substrate produced with the most efficient conditions removed 91% of the lignin and 89.1% of the hemicellulose with no loss of cellulose. Enzymatic hydrolysis of this biomass was 90% to 95%, with a substrate concentration of 3% and with five filter paper units per gram of cellulose (FPU/g cellulose). These results indicated that this one-step alkaline-organsolvent process, applied as a pretreatment to softwood, allows highly efficient lignin and hemicellulose removal. 100% of cellulose was recovered, and there was between 90 and 95% glucose yield after enzymatic digestion.

The effect of organosolv pretreatment on optimization of hydrolysis process to produce the reducing sugar

As the fossil energy decrease such as petroleum and natural gas, that are encourages a lot of research to develop new sources of energy from renewable raw materials. One of the source is through reducing sugar (glucose and xylose) obtained from coffee pulp waste; this is due to abundant production of coffee pulp every year reaching 743 kg/ha. In addition, this waste has not been used optimally and the cellulose and hemicellulose content of the coffee is high. The purpose of this study is to get the optimal operating condition for reducing sugar production from coffee pulp waste. The method used for optimization is Response Surface Methodology with Central Composite Design. The optimum operation condition obtained was pH 4.63 at 34ºC for 16.29 hours of hydrolysis. As a result, the predicted yield gained was 0.147 grams of reducing sugars / gram of cellulose+hemicellulose. The result indicates the gained yield was 0.137 grams of reducing sugars / gram of cellulose+hemicellulose.

Paper-based diagnostics in the antigen-depletion regime: High-density immobilization of rcSso7d-cellulose-binding domain fusion proteins for efficient target capture

In this work, we report the development of a general strategy for enhancing the efficiency of target capture in immunoassays, using a bifunctional fusion protein construct which incorporates a substrate-anchoring moiety for the high-abundance immobilization of an antigen-binding domain. This approach was informed by the development of a pseudo first-order rate constant model, and tested in a paper-based assay format using a fusion construct consisting of an rcSso7d binding module and a cellulose-binding domain. These rcSso7d-CBD fusion proteins were solubly expressed and purified from bacteria in high molar yields, and enable oriented, high-density adsorption of the rcSso7d binding species to unmodified cellulose within a 30-second incubation period. These findings were validated using two distinct, antigen-specific rcSso7d variants, which were isolated from a yeast surface display library via flow cytometry. Up to 1.6 micromoles of rcSso7d-CBD was found to adsorb per gram of cellulose, yielding a volume-averaged binder concentration of up to 760μM within the resulting active material. At this molar abundance, the target antigen is captured from solution with nearly 100% efficiency, maximizing the attainable sensitivity for any given diagnostic system.

Synergistic action of an Aspergillus (hemi-)cellulolytic consortium on sugarcane bagasse saccharification

This study evaluated the synergistic efficiency of crude enzymatic extracts (CEE) produced by fungal strains Aspergillus fumigatus SCBM6 (AFE) and Aspergillus niger SCBM1 (ANE) in the hydrolysis of alkali pretreated sugarcane bagasse (2% NaOH (w v−1), ∼100 °C, 4 h and liquid-to-solid ratio of 25 (v w−1)). CEEs were produced by solid-state fermentation (SSF) and presented high concentration of β-glucosidase (AFE = 78.4 U g−1 and ANE = 43.02 U g−1), β-xylosidase (ANE = 78.0 U g−1) and xylanase (AFE = 1774.5 U g−1 and ANE = 3289.6 U g−1). A 24 full design of experiments was used to optimize the hydrolysis of pretreated bagasse as a function of time, temperature, amount of pretreated bagasse and AFE-to-ANE ratio. After hydrolysis optimization, the maximum concentration of total reducing sugars (TRS) was 21.68 g L−1. It was also noticed a significant production of xylose (135.59 mg) and arabinose (58.10 mg) per gram of hemicelluloses and a slight production of glucose (20.18 mg) per gram of cellulose. As fungi consortium were excellent producers of hemicellulases, it is suggested that they could be used for pentoses saccharification and production of ethanol via C-5 fermentation, xylitol, biopolymers, among other bioproducts.

Industrial cellulase performance in the simultaneous saccharification and co-fermentation (SSCF) of corn stover for high-titer ethanol production

BackgroundCellulase enzymes contribute to the largest portion of operation cost on production of cellulosic ethanol. The industrial cellulases available on the industrial enzyme market from different makers and sources vary significantly in hydrolysis and ethanol, and finally lead to the changes of enzyme cost. Therefore, the selection of the proper industrial cellulase enzymes for commercial-scale production of cellulosic ethanol is crucially important in terms of high performance and cost reduction.ResultsIn this study, three major cellulase enzyme products available on the Chinese industrial enzyme market were selected and evaluated as the biocatalysts for the biorefining process of lignocellulose biomass into high-titer ethanol. The cellulase enzymes included Cellic CTec 2.0 from Novozymes (Beijing), and LLC 4 from Vland (Qingdao), as well as # 7 from an industrial enzyme maker. The detailed assays on the filter paper activity, the cellobiase activity, and the total protein contents of the enzymes were conducted according to the standard protocols. When the cellulase enzymes were applied to the practical hydrolysis and ethanol-fermentation operation under the conditions of high solids loading and low range of cellulase dosage, the hydrolysis yield shows the significant difference, and the difference was narrowed in the final ethanol yield.ConclusionsThe commercially available cellulase enzymes showed different performances in the activities, the cellulose hydrolysis yield, and the ethanol fermentation yields based on the protein dosage per gram of cellulose of corn stover. In general, the industrial cellulase products give satisfactory performance and can be applied for the practical cellulosic ethanol production on commercial scale.

Microwave-assisted carboxymethylation of cellulose extracted from brewer's spent grain

Cellulose was extracted from brewer's spent grain (BSG) by alkaline and bleaching treatments. The extracted cellulose was used in the preparation of carboxymethyl cellulose (CMC) by reaction with monochloroacetic acid in alkaline medium with the use of a microwave reactor. A full-factorial 23 central composite design was applied in order to evaluate how parameters of carboxymethylation process such as reaction time, amount of monochloroacetic acid and reaction temperature affect the average degree of substitution (DS¯) of the cellulose derivative. An optimization strategy based on response surface methodology has been used for this process. The optimized conditions to yield CMC with the highest DS¯ of 1.46 follow: 5g of monochloroacetic acid per gram of cellulose, reaction time of 7.5min and temperature of 70°C. This work demonstrated the feasibility of a fast and efficient microwave-assisted method to synthesize carboxymethyl cellulose from cellulose isolated of brewer's spent grain.

Ionic Liquid Pretreatment of Rice Straw to Enhance Saccharification and Bioethanol Production

In this study, rice straw was pretreated by an ionic liquid, 1-ethyl-3-methylimidazolium acetate ((EMIM)(OAc)), prior to enzymatic hydrolysis and ethanol production. The pretreatment was carried out at 120 °C for 5 h under atmospheric pressure. Afterward, saccharification was conducted at 45 °C for 72 h using 20 FPU cellulase and 30 IU β- glucosidase per gram of cellulose. Glucose yield was significantly increased from 25.7% for the untreated straw to over 75% for the treated straw. Moreover, the ethanol yield by simultaneous saccharification and fermentation was improved from 35.6% for the untreated straw to 79.7% for the treated straw. SEM images showed more open and accessible structure for the treated straw compared to the untreated one which assisted the penetration of hydrolytic enzymes in the saccharification and fermentation. From FTIR analysis, it was suggested that the crystallinity reduction and conversion of cellulose I to II are the main changes in the straw as a result of the pretreatment.

Enzymatic properties of Thermoanaerobacterium thermosaccharolyticum β-glucosidase fused to Clostridium cellulovoranscellulose binding domain and its application in hydrolysis of microcrystalline cellulose

BackgroundThe complete degradation of the cellulose requires the synergistic action of endo-β-glucanase, exo-β-glucanase, and β-glucosidase. But endo-β-glucanase and exo-β-glucanase can be recovered by solid–liquid separation in cellulose hydrolysis by their cellulose binding domain (CBD), however, the β-glucosidases cannot be recovered because of most β-glucosidases without the CBD, so additional β-glucosidases are necessary for the next cellulose degradation. This will increase the cost of cellulose degradation.ResultsThe glucose-tolerant β-glucosidase (BGL) from Thermoanaerobacterium thermosaccharolyticum DSM 571 was fused with cellulose binding domain (CBD) of Clostridium cellulovorans cellulosome anchoring protein by a peptide linker. The fusion enzyme (BGL-CBD) gene was overexpressed in Escherichia coli with the maximum β-glucosidase activity of 17 U/mL. Recombinant BGL-CBD was purified by heat treatment and following by Ni-NTA affinity. The enzymatic characteristics of the BGL-CBD showed optimal activities at pH 6.0 and 65°C. The fusion of CBD structure enhanced the hydrolytic efficiency of the BGL-CBD against cellobiose, which displayed a 6-fold increase in V max /K m in comparison with the BGL. A gram of cellulose was found to absorb 643 U of the fusion enzyme (BGL-CBD) in pH 6.0 at 50°C for 25 min with a high immobilization efficiency of 90%. Using the BGL-CBD as the catalyst, the yield of glucose reached a maximum of 90% from 100 g/L cellobiose and the BGL-CBD could retain over 85% activity after five batches with the yield of glucose all above 70%. The performance of the BGL-CBD on microcrystalline cellulose was also studied. The yield of the glucose was increased from 47% to 58% by adding the BGL-CBD to the cellulase, instead of adding the Novozyme 188.ConclusionsThe hydrolytic activity of BGL-CBD is greater than that of the Novozyme 188 in cellulose degradation. The article provides a prospect to decrease significantly the operational cost of the hydrolysis process.

Valorization of an agro-industrial waste, mango seed, by the extraction and characterization of its cellulose nanocrystals

Mango seeds are lignocellulosic agro-industrial residues available in large quantities in tropical countries and are simply discarded or used as animal feed. They are a natural and renewable resource, and were used to generate new polymeric materials in this work. This new materials can be used as alternatives to fossil resources such as petroleum. This work aimed to extract and characterize cellulose nanocrystals (CN) from mango seed by acid hydrolysis to obtain a material suitable as a reinforcing agent in the manufacturing of nanocomposites. The fibers of mango seeds were ground in mills and purified mainly to remove lignin. The raw mango seed (MS) and the purified mango seed (PMS) were analyzed for chemical composition and characterized by infrared and X-rays. Cellulose nanocrystals from the mango seed (CNM) were isolated by acid hydrolysis at 40 °C for 10 min, with 20 ml of H2SO4 (11.21 M) used for every gram of cellulose. The yield at this step was 22.8%. CNM were needle-shaped, with high crystallinity (90.6%), good thermal stability (around 248 °C), a medium length (L) of 123.4 ± 22.1 nm and a diameter (D) of 4.59 ± 2.22 nm, giving an aspect ratio (L/D) of about 34.1 ± 18.6. The diameter measurements of CNM were also confirmed by Scherrer's equation. This work also aimed to reuse mango seed produced as industrial waste, giving it a useful application and preventing its role as an environmental pollutant.

Extraction and characterization of cellulose nanocrystals from corncob for application as reinforcing agent in nanocomposites

Corncob is an agro-industrial waste available in large quantities in several countries, including Brazil, which deserves to be better and/or properly used. This work evaluates the use of corncob as a source of cellulose to obtain nanocrystals by acid hydrolysis in order to obtain a material suitable to be a reinforcement agent in the manufacture of nanocomposites. The hydrolysis was performed at 45°C for 30, 60 and 90min, using 15mL of H2SO4 (9.17M) for each gram of cellulose. The resulting cellulose nanocrystals of corncob (CNC) were characterized by crystallinity index, morphology and thermal stability, and their reinforcing capability was evaluated using polyvinyl alcohol (PVA) as the polymeric matrix. Among the hydrolysis conditions carried out, the extraction time of 60min resulted in nanoparticles (CNC60) with larger reinforcing capability. The CNC60 endowed the CNC/PVA composites with a significantly improved tensile strength of 140.2% when only 9% (wt.%) CNC60 was incorporated. The CNC60 presented a needle-shaped nature, high crystallinity (83.7%), good thermal stability (around 185°C), an average length (L) of 210.8±44.2nm and a diameter (D) of 4.15±1.08nm, giving an aspect ratio (L/D) of around 53.4±15.8. The results show that the more suitable filler was CNC60. Since CNC60 has the highest crystallinity among the CNC samples, but does not have the highest aspect ratio, these results suggest that the difference in the crystallinity index has a greater influence on the tensile properties than the aspects ratio, in this case. Cellulose nanocrystals obtained from corncob have great potential as reinforcing agents for the manufacture of nanocomposites.

Extraction and characterization of cellulose nanocrystals from agro-industrial residue – Soy hulls

Soy hulls are an agro-industrial residue available in huge quantities throughout the world whose application deserves more attention than simply as cattle feed. This work evaluates the use of soy hulls as a source of cellulose to obtain nanocrystals by acid hydrolysis. The hydrolysis was performed at 40°C for 30 or 40min, using 30mL of H2SO4 64% for each gram of cellulose. The resulting nanocrystals were characterized by crystallinity index, morphology, surface charge and thermal stability. The results showed that the more drastic hydrolysis conditions (40min) resulted in a shorter length of nanocrystals and caused some damage on the crystalline structure of the cellulose. At an extraction time of 30min, the nanocrystals presented a high crystallinity (73.5%), an average length of 122.66±39.40nm, a diameter of 2.77±0.67nm and an aspect ratio around 44, therefore presenting a great potential as reinforcement in nanocomposite preparations.

Dilute Sulfuric Acid Pretreatment and Enzymatic Hydrolysis of Corn Stover into Fermentable Sugars

The pretreatment of corn stover with dilute sulfuric acid has been investigated by varying the acid concentration (0.5%-1.25%(w/w)) and the temperature (130-160°C). The pretreatment is aimed at improving enzymatic hydrolysis and increasing the fermentability of the biomass. Given the overall sugar yield, the most favourable pretreatment condition was performed with 0.75% sulfuric acid at 150°C for 30min and then with an enzyme loading of cellulase 15 FPU per gram of cellulose, and it resulted in a total of 49.74g glucose and xylose from 100g dry corn stover. The fiber physical feature, structure and property of pretreated residues were studied with Scanning Electron Microscope (SEM) and Fourier transform infrared spectroscopy. The SEM pictures indicated that the biomass structure was deformed and its fibers were exposed by the pretreatment. FTIR study showed that lignin and hemicellulose were partially removed during the diluted sulfuric acid pretreatment.

Synthesis of galactooligosaccharides by CBD fusion β-galactosidase immobilized on cellulose

The β-galactosidase gene (bgaL3) was cloned from Lactobacillus bulgaricus L3 and fused with cellulose binding domain (CBD) using pET-35b (+) vector in Escherichia coli. The resulting fusion protein (CBD-BgaL3) was directly adsorbed onto microcrystalline cellulose with a high immobilization efficiency of 61%. A gram of cellulose was found to absorb 97.6U of enzyme in the solution containing 100mM NaCl (pH 5.8) at room temperature for 20min. The enzymatic and transglycosylation characteristics of the immobilized CBD-BgaL3 were similar to the free form. Using the immobilized enzyme as the catalyst, the yield of galactooligosaccharides (GOS) reached a maximum of 49% (w/w) from 400g/L lactose (pH 7.6) at 45°C for 75min, with a high productivity of 156.8g/L/h. Reusability assay was subsequently performed under the same reaction conditions. The immobilized enzyme could retain over 85% activity after twenty batches with the GOS yields all above 40%.

Flow-through pretreatment with strongly acidic electrolyzed water for hemicellulose removal and enzymatic hydrolysis of corn stover

The application of strongly acidic electrolyzed water (SAEW) in a flow-through system for the treatment of recalcitrant corn stover resulted in enhanced hemicellulose degradation at 160°C and 180°C compared to hydrochloric acid treatment under the same pH. Pretreatment conditions were optimized by varying the four main factors: pH, flow rate, temperature, and reaction time. About 96% of the hemicellulose was removed when corn stover was treated at 180°C for 20min, with SAEW at pH 2.0 and a flow rate of 10mL/min. The recovery of total monomeric and oligomeric xylose in the liquid fraction reached 93%. Using 30 filter paper units of cellulase per gram of cellulose, a digestibility of 100% was achieved under these conditions. Therefore, flow-through SAEW pretreatment is an efficient way to remove hemicellulose and improve enzymatic digestibility of corn stover.