Hemicellulose Components Research Articles

Valorization of paper industry rejects by combined thermo-chemical pretreatment and biological conversion to L-lysine

Paper and pulp industry is one of the biggest industries that generate waste material and waste water. Conversion of the industrial waste to renewable products through green process is one of the recent trends for the production of renewable fuels and other industrially important bioproducts like bioethanol, biobutanol and bioplastics. In pulp and paper industry, the main process for the production of cellulose pulp is Kraft process and various wastes are generated during this process. These wastes mainly contain the plant biomass which consists carbohydrates like cellulose, hemicellulose and other components of the wood. The present work focuses on the potential of utilizing paper industry rejects for the production of amino acids. The paper rejects were pretreated using mild acids and hydrolyzed enzymatically using cellulases. The effect of the acid pretreatment and hydrolysis on cellulose fiber structure were studied. The pretreatment and hydrolysis yielded 37% sugar from the paper rejects and the glucose obtained was used for subsequent lysine fermentation. Maximum sugar yield was observed when the pretreatment was carried out in a laboratory autoclave at 121 ºC for 30 min at 15 lb pressure. When the pretreatment is carried out at higher temperature charring occurred which resulted in a reduction in glucose yield. The study was further outstretch by appraising the fermentability of using the paper reject hydrolyzateblended with CGXII synthetic medium in 1:1 ratio for L-lysine production using a strain of Corynebacterium glutamicum DM1729 which resulted in the production of 11.5 mg/ml lysine compared to 15.1 mg/ml obtained from pure synthetic medium. • Paper industry rejects as a suitable substrate for the production of value added products. • Acid pretreated hydrolyzate suitable for lysine production. • Corynebacterium glutamicum DM1729 produced 11.5 mg/ml of lysine.

Production of Nanocellulose Crystal Derived from Enset Fiber Using Acid Hydrolysis Coupled with Ultrasonication, Isolation, Statistical Modeling, Optimization, and Characterizations

Currently, many scholars are looking for renewable biomass sources for the isolation of nanomaterials that have a sustainable property and are ecofriendly. Thus, effectively synthesize and characterization enset fiber nanocellulose using acid hydrolysis with sonication is focus of study. Additionally, process optimization for isolation of nanocellulose (CNCs) from raw enset fiber using RSM-CCD and characterizations of obtained CNCs was explored. The quadratic model was selected, and optimized values for CNCs yield (77.69%) that were acquired to be H2SO4: 51.6 wt. %, reaction temperature: 47°C, and time: 66.5 min. Chemical composition analysis, XRD, FTIR, PSA, SEM, and TGA were used for characterizing CNCs. The particle size distribution of CNCs is 66 nm. It has a crystalline index of 80.91% and excellent thermal stability. FTIR and chemical composition result indicated the reduction and removal of lignin and hemicellulose components that are usually available in the raw enset fibers. The SEM analysis reveals the structure and arrangement of the fiber bundles inside the raw material to nanocellulose. This property shows its endowing as a possibly consistent load-bearing material. This study could be given a noteworthy thought for designing and emerging CNC isolation, optimization, and industrial application.

Evaluation of hydrogel use in the development of Rapanea ferruginea with water restriction by vibrational Fourier Transform Infrared Spectroscopy (FTIR-UATR)

This study evaluated the use of hydrogel on the development of Rapanea ferruginea under water restriction through Vibrational Fourier Transform Infrared Spectroscopy (FTIR-UATR). Seedlings of approximately 30 cm height were transferred in pots with 3 L of soil. The group of seedlings was separated into 5 different triplicate treatments according to the amount of hydrogel, as follows: H1 (25%), H2 (20%), H3 (15%), H4 (10%) and S (control without hydrogel). The applied hydrogel was mixed homogeneously with the soil. All treatments were irrigated with 40 mL of water. FTIR spectra were obtained from fresh leaves collected during 13 months of monitoring. The correlation of the hydroxyl (water) band with the main biomolecules between treatments with the control was evaluated using the Mann-Whitney test (p<0.05). The biomolecule bands were subjected to principal component analysis (PCA) and hierarchical clustering analysis (HCA). The results indicate a significant correlation of the water band with the lipid, hemicellulose, cell wall and starch components in the species. The use of hydrogel resulted in a significant difference in the water absorption band in relation to the control group through the Mann-Whitney test and in biomolecules as the HCA and PCA analysis suggested. The best development was observed in groups H4 (10%), H2 (20%) and H3 (15%). The use of hydrogel positively influences the biomolecular development of the Rapanea ferruginea and monitoring is viable by FTIR.
 Keywords: FTIR infrared spectroscopy, plant water management, superabsorbent polymer.

The significant role of electron donating capacity and carbon structure of biochar to electron transfer of zerovalent iron

Herein, the major biochar properties were correlated with electron transfer of zerovalent iron (ZVI) and contribution of biomass constituents to biochar property was ascertained to optimize electron transfer of ZVI. To this end, five respective stalk-type and wood-type lignocellulosic biomasses were pyrolzed at 600 °C to prepare biochars to harbor ZVI (ZVI/BC). Thermogravimetric analysis demonstrated woody biomasses decomposed more intensively at higher temperature relative to stalky biomass. ZVI/BC were characterized with Raman, X-ray diffraction, and electrochemical analyses including electron donating capacity (EDC) and electron accepting capacity (EAC). Pearson correlation and partial least-squares (PLS) analyses confirmed that Cr(VI) reduction capacity was negatively related to Tafel corrosion potential and intensity ratio of ID/IG, but significantly positively-related to EDC of BC, in which EDC was a predominant attribute to contribute to reductive capacity toward Cr(VI) reduction. That is, greater EDC and higher graphitic carbon structure of biochar due to cellulose and hemicellulose components favor electron transfer of ZVI toward Cr(VI) reduction.

Tree bark utilization in insulating bio‐aggregates: a review

AbstractThis review gives an overview of recent advances in research on the role of tree bark material in bark‐cement bio‐composites, and their potential as building insulation materials. Suberin and other bark extractives seem to be of great importance for the insulation properties of such composites. Bark is a readily available, biological raw material with unique properties and it has revealed promising results as a bio‐insulation material, either alone or in mixtures with different matrices (cement, lime, resins, polymers, etc.). The thermal, mechanical, acoustic, and hygroscopic properties of these bark‐insulating composites depend on several factors, primarily the type of tree bark, the density and mechanical strength of the bark, the density of the boards produced, and the ratio of bark material to the binder material used in the board production (cement, lime, resins, polymers, etc.). The size of granules and the thickness of the board produced seem to be factors with a lower impact on the properties of the bark‐cement composites. A low proportion of bark fibers or particles (0.5–1%) in bark‐cement composites has proven highly beneficial to their mechanical and thermal properties and ensures higher workability of the mixture. Different modification treatments of bark material should be investigated, with the aim of decreasing the bark extractives content, to improving the cement setting, decreasing the unstable hemicellulose components and their hygroscopic nature, improving the bark particles’ durability in alkaline environments, and upgrading their adherence properties. As the demand for alternative, sustainable structural materials keeps rising, the cement‐bark composites will undoubtedly keep attracting the attention of the scientific and industrial world. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

Extraction of Microcrystalline Cellulose from Washingtonia Fibre and Its Characterization.

Washingtonia is a desert plant with great sustainability and renewability in nature and is abundantly cultivated across global urban regions. Its fibre biomass comprises cellulose as the major structural part, and this is why it can be potentially utilized as an alternative biomaterial for manufacturing microcrystalline cellulose (MCC) products that can be widely applied in industrial fields. In the present study, NaOH-treated Washingtonia fibre (WAKL), NaClO2-treated Washingtonia fibre (WBLH), and Washingtonia microcrystalline cellulose (WMCC) were extracted through combined treatments of alkalization, bleaching, and acidic hydrolysis, respectively. The obtained chemically treated fibre samples were subjected to characterization to investigate their morphology, physico-chemistry, and thermal stability. In a morphological examination, the large bunch WAKL fibre reduced into small size WMCC fibrils, evidencing that the lignin and hemicellulose components were greatly eliminated through chemical dissolution. The elemental composition revealed that almost all impurities of anions and cations had been removed, particularly for the WMCC sample, showing its high purity of cellulose content. Additionally, the WMCC sample could attain at 25% yield, giving it the advantage for feasible economic production. Furthermore, the physicochemical analysis, Fourier Transform Infrared-ray (FTIR), indicated the presence of a crystalline cellulose region within the WMCC structure, which had promoted it with high crystallinity of 72.6% as examined by X-ray diffraction (XRD). As for thermal analysis, WMCC showed greater thermal stability comparing to WAKL and WBLC samples at high temperature. Therefore, Washingtonia fibre can be a reliable biosubstituent to replace other plant material for MCC production in the future.

Pectin and Xylan Biosynthesis in Poplar: Implications and Opportunities for Biofuels Production.

A potential method by which society's reliance on fossil fuels can be lessened is via the large-scale utilization of biofuels derived from the secondary cell walls of woody plants; however, there remain a number of technical challenges to the large-scale production of biofuels. Many of these challenges emerge from the underlying complexity of the secondary cell wall. The challenges associated with lignin have been well explored elsewhere, but the dicot cell wall components of hemicellulose and pectin also present a number of difficulties. Here, we provide an overview of the research wherein pectin and xylan biosynthesis has been altered, along with investigations on the function of irregular xylem 8 (IRX8) and glycosyltransferase 8D (GT8D), genes putatively involved in xylan and pectin synthesis. Additionally, we provide an analysis of the evidence in support of two hypotheses regarding GT8D and conclude that while there is evidence to lend credence to these hypotheses, there are still questions that require further research and examination.

Improving the catalytic performance of xylanase from Bacillus circulans through structure-based rational design

Endo-1,4-β-xylanase is one of the most important enzymes employed in biorefineries for obtaining fermentable sugars from hemicellulosic components. Herein, we aimed to improve the catalytic performance of Bacillus circulans xylanase (Bcx) using a structure-guided rational design. A systematic analysis of flexible motions revealed that the R49 component of Bcx (i) constrains the global conformational changes essential for substrate binding and (ii) is involved in modulating flexible motion. Site-saturated mutagenesis of the R49 residue led to the engineering of the active mutants with the trade-off between flexibility and rigidity. The most active mutant R49N improved the catalytic performance, including its catalytic efficiency (7.51-fold), conformational stability (0.7 °C improvement), and production of xylose oligomers (2.18-fold higher xylobiose and 1.72-fold higher xylotriose). The results discussed herein can be applied to enhance the catalytic performance of industrially important enzymes by controlling flexibility.

Lignocellulosic biomass-based pyrolysis: A comprehensive review

The efficacious application of lignocellulosic biomass for the new valuable chemicals generation curbs the excessive dependency on fossil fuels. Among the various techniques available, pyrolysis has garnered much attention for conversion of lignocellulosic biomass (encompasses cellulose, hemicellulose and lignin components) into product of solid, liquid and gases by thermal decomposition in an efficient manner. Pyrolysis conversion mechanism can be outlined as formation of char, depolymerisation, fragmentation and other secondary reactions. This paper gives a deep insight about the pyrolytic behavior of the lignocellulosic components accompanied by its by-products. Also several parameters such as reaction environment, temperature, residence time and heating rate which has a great impact on the pyrolysis process are also elucidated in a detailed manner. In addition the environmental and economical facet of lignocellulosic biomass pyrolysis for commercialization at industrial scale is critically analyzed. This article also illustrates the prevailing challenges and inhibition in implementing lignocellulosic biomass based pyrolysis with possible solution.

Influence of Sequential Acid-alkali Treatment on Palm Biomass Waste Properties

ABSTRACT Palm biomass (Archontophoenix alexandrae) is a natural crop of the food industry, even with a high potential to produce sustainable and innovative products. Thus, the purpose of this work was to evaluate the effect of sequential acid-alkali treatment followed by precipitation with concentrated H2SO4 on fiber’s microstructure, chemical, and physical properties. So, the raw fiber, the pre-treated fiber, and the precipitated lignin were characterized by scanning eléctron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). Results indicated changes in lignocellulosic structure by SEM analysis, which confirms the defibrillation due to the reduction of the average diameter and lengths of treated fiber compared to raw fiber (~50%). FTIR and XRD also proved the partial removal of amorphous structures such as hemicellulose and lignin components, with changes in the intensity of absorption bands and the increase in the crystalline index after the sequential treatment (~58%). TGA and DTG analysis provided evidence of an enhancement in treated fiber and lignin’s thermal stability compared to raw fiber, confirming the adopted methodology’s efficiency to isolate the main lignocellulosic structures and disrupting the biomass recalcitrance.

Purification of Xylooligosaccharide From Casavva Pulp by Ultrafiltration Method

Xylan is the main component of hemicellulose. Xylan can be extracted from agricultural waste, such as cassava pulp. Xylan is used as an endo-β-1,4-D-xylanase substrate to produce impure xylooligosaccharides (XOS)This study aims to purify XOS from cassava pulp using the ultrafiltration method. The components of XOS obtained from the enzymatic hydrolysis were analyzed using thin layer chromatography (TLC) and densitometry methods. In addition, the XOS was purified by the ultrafiltration method using a cellulose membrane with a Molecular Weight Cut Off (MWCO) of 12 kDa. The permeate obtained from the purification results was also analyzed using TLC and densitometry. The results of this study indicated that the components in XOS cassava pulp before and after purification by the TLC method were X5 and X6, while the XOS components before and after purification by the densitometric method were X3, X4 and X5.

Unlocking the structural features for the xylobiohydrolase activity of an unusual GH11 member identified in a compost-derived consortium.

The heteropolysaccharide xylan is a valuable source of sustainable chemicals and materials from renewable biomass sources. A complete hydrolysis of this major hemicellulose component requires a diverse set of enzymes including endo-β-1,4-xylanases, β-xylosidases, acetylxylan esterases, α-l-arabinofuranosidases, and α-glucuronidases. Notably, the most studied xylanases from glycoside hydrolase family 11 (GH11) have exclusively been endo-β-1,4- and β-1,3-xylanases. However, a recent analysis of a metatranscriptome library from a microbial lignocellulose community revealed GH11 enzymes capable of releasing solely xylobiose from xylan. Although initial biochemical studies clearly indicated their xylobiohydrolase mode of action, the structural features that drive this new activity still remained unclear. It was also not clear whether the enzymes acted on the reducing or nonreducing end of the substrate. Here, we solved the crystal structure of MetXyn11 in the apo and xylobiose-bound forms. The structure of MetXyn11 revealed the molecular features that explain the observed pattern on xylooligosaccharides released by this nonreducing end xylobiohydrolase.

Boosted activity of Cu/SiO2 catalyst for furfural hydrogenation by freeze drying

The biomass valorization is of great importance as an alternative for the production of transport fuels and fine chemicals. Furfural hydrogenation to furfuryl alcohol is a prevailing industrial route for the utilization of hemicellulose component of biomass. The toxicity of the chromium species in commercial copper chromite catalyst for furfuryl alcohol production motivates the development of efficient chromium-free catalyst. Thus, a highly efficient silica supported copper catalyst is developed in this study. The catalyst is prepared by freeze drying of a gel precursor that is synthesized by ammonia evaporation, followed by calcination and H2 reduction. The catalyst exhibits higher furfural hydrogenation activity than oven dried catalyst, commercial copper chromite catalyst and a plant supplied commercial silica supported copper catalyst. The catalyst also shows good stability. The superior performance of the freeze dried catalyst has resulted from its developed pore structure and higher amount of Cu0 as well as Cu+ active sites.

Chemistry of lignin and hemicellulose structures interacts with hydrothermal pretreatment severity and affects cellulose conversion.

Understanding of how the plant cell walls of different plant species respond to pretreatment can help improve saccharification in bioconversion processes. Here, we studied the chemical and structural modifications in lignin and hemicellulose in hydrothermally pretreated poplar and wheat straw using wet chemistry and 2D heteronuclear single quantum coherence nuclear magnetic resonance (NMR) and their effects on cellulose conversion. Increased pretreatment severity reduced the levels of β─O─4 linkages with concomitant relatively increased levels of β─5 and β─β structures in the NMR spectra. β─5 structures appeared at medium and high severities for wheat straw while only β─β structures were observed at all pretreatment severities for poplar. These structural differences accounted for the differences in cellulose conversion for these biomasses at different severities. Changes in the hemicellulose component include a complete removal of arabinosyl and 4-O-methyl glucuronosyl substituents at low and medium pretreatment severities while acetyl groups were found to be relatively resistant toward hydrothermal pretreatment. This illustrates the importance of these groups, rather than xylan content, in the detrimental role of xylan in cellulose saccharification and helps explain the higher poplar recalcitrance compared to wheat straw. The results point toward the need for both enzyme preparation development and pretreatment technologies to target specific plant species.

Direct Conversion of Sugarcane Bagasse into an Injection-Moldable Cellulose-Based Thermoplastic via Homogeneous Esterification with Mixed Acyl Groups

Recently, lignocellulosic biomass-based plastics have attracted attention as alternatives to oil-derived plastics. However, the conventional production of biomass-based plastics is a multistep process, requiring harsh pretreatment, chemical modification, and purification, resulting in high costs and environmental burden. Herein, we report the direct conversion of lignocellulosic agricultural waste, sugarcane bagasse, into an injection-moldable cellulosic thermoplastic having good mechanical properties. Specifically, the hydroxy groups in bagasse were substituted by long-/short-chain mixed acyl groups (20:80 molar ratio of decanoyl/acetyl groups) in a one-pot, two-step homogeneous transesterification reaction using the corresponding vinyl esters and an ionic liquid (1-ethyl-3-methylimidazolium acetate) as both solvent and catalyst. The lignin component in the bagasse derivative was separated by precipitation in methanol, and a mixed-ester derivative of cellulose and hemicellulose (polysaccharide acetate decanoate, PSAD) having long- and short- acyl chains was obtained. PSAD could be injection-molded at 205 °C because of the plasticizing effects of the decanoyl groups and the hemicellulose component, despite the ultrahigh weight-average molecular weight of >1.5 × 10⁶ g mol–¹. The hemicellulose derivative in PSAD yielded moderate flexibility and sufficiently high mechanical strength for its use as a thermoplastic with tensile and flexural strengths of 50 and 80 MPa, respectively.

Integration of hemicellulose pre-extraction and solid alkali-oxygen cooking processes for lignocellulose fractionation with emphasis on xylan valorization

Cooking with active oxygen and solid alkali (CAOSA) is a mild and environmentally friendly method for separation of lignin components. The degradation mechanism of hemicellulose associated with this method has been investigated. It was found that the hemicellulose-derived polysaccharides were directly oxidized rather than hydrolyzed to monosaccharides for degradation. To avoid the undesirable degradation of hemicellulose components by CAOSA, the idea of separating hemicellulose first in the form of xylan to produce xylooligosaccharide was presented by this study. Although hydrothermal autocatalysis has been commonly used in hemicellulose separation, the effects of acid-enhanced hydrothermal method and alkali-suppressed hydrothermal method on hydrothermal autocatalysis were systematically compared for the first time, and it was found that the acid-enhanced method was beneficial for highly selective extraction of xylan. Then, the hemicellulose-removed bamboo was treated with CAOSA process to separate lignin from cellulose. It was found that solid alkali dosage of CAOSA could be evidently decreased for hemicellulose-removed bamboo, which was helpful to reduce the cost of CAOSA. Coupling hemicellulose pre-extraction and CAOSA lignin fractionation strategy, a comprehensive biorefinery case for bamboo biomass could be anticipated.

Xylan Decomposition in Plant Cell Walls as an Inducer of Surfactin Synthesis by Bacillus subtilis.

Hemicellulose is the second most abundant plant heterogenous biopolymer. Among products obtained from a wide range of agro-residues, biosurfactants, e.g., surfactin (SU), are gaining increasing interest. Our previous studies have shown that a Bacillus subtilis strain can successfully produce a significant amount of SU using a rapeseed cake. This work aimed to investigate plant hemicellulose components as substrates promoting SU’s efficient production by B. subtilis 87Y. Analyses of SU production, enzymatic activity and cell wall composition of hulled oat caryopses suggest that the main ingredients of plant hemicellulose, in particular xylan and its derivatives, may be responsible for an increased biosurfactant yield.

Effect of lignocellulosic fiber composition on the aquatic biodegradation of wood pulps and the isolated cellulose, hemicellulose and lignin components: kinetic modelling of the biodegradation process

The importance of renewable and environmentally friendly wood pulp fibers as an input material for single-use products has grown significantly. However, discarded single-use materials are found in the environment as litter and are sometimes disposed of in wastewater. It is important that these materials are biodegradable and environmentally benign. Wood pulp is mainly comprised of lignocellulosic material, and its composition and structure can vary depending on raw materials and processing, ultimately impacting the biodegradability. In this research, the aquatic biodegradation of five kinds of wood pulp and six different samples of isolated lignocellulosic components (cellulose, hemicellulose, and lignin) have been explored in a consistent detailed manner for the first time, and the effects of chemical composition on the biodegradation discussed. Several lignocellulosic materials were characterized using compositional analysis and were subjected to aquatic biodegradation with bio-solids from a wastewater treatment plant as an inoculum to indicate the potential to biodegrade in the environment. Cellulose and hemicellulose were readily biodegraded over a course of one month. The lignin samples were not biodegradable under these conditions, and the lignin within fibers decreased the biodegradability of the other components of the lignocellulosic fibers. It was also determined that ash and extractives negatively affect the biodegradability. The aerobic aquatic biodegradation results are useful for product designers to select different lignocellulosic materials for applications and for environmental scientists to understand the fate of these fibers in the environment.

TAGUCHI ORTHOGONAL DESIGN FOR OPTIMIZING A UNIFIED TERNARY PROCESS TO VALORIZE OIL PALM LEAVES FOR NANOCELLULOSE ISOLATION

Oil palm leaves (OPL), as the major component of oil palm biomass, was capitalized for the isolation of nanocellulose (NC) by unified ternary acoustic, chemical- and enzyme-assisted techniques. This study aimed to statistically optimize the extraction parameters via the Taguchi Design for sonication time, duration of enzymatic hydrolysis, the concentration of acid, and the duration of acid hydrolysis, for the highest crystallinity of the isolated NC. The optimum condition required a sonication duration of 20 min, 1 h of acid hydrolysis in 6 M of H2SO4 and 1 h of enzymatic hydrolysis that resulted in the production of NC with a maximum 68.2% crystallinity index, based on X-ray diffraction (XRD) data. Duration of sonication time and acid hydrolysis was crucial for improving the crystallinity of isolated NC. The reduced C=O and C=C peaks at 1734 cm-1 and 1536 cm-1, respectively, in the Fourier-transform Infrared (FTIR) spectra of isolated NC, confirmed the removal of appreciable amounts of hemicellulose and lignin components in the OPL fibers. FESEM micrographs revealed the needle-like structures of NC with diameters between 21‒24.8 nm. The NC isolation approach presented here offers a promising avenue to ease the use of harsh acids for biomass pretreatment.

Co-production of Xylooligosaccharides and Xylose From Poplar Sawdust by Recombinant Endo-1,4-β-Xylanase and β-Xylosidase Mixture Hydrolysis.

As is well-known, endo-1,4-β-xylanase and β-xylosidase are the rate-limiting enzymes in the degradation of xylan (the major hemicellulosic component), main functions of which are cleavaging xylan to release xylooligosaccharides (XOS) and xylose that these two compounds have important application value in fuel, food, and other industries. This study focuses on enzymatic hydrolysis of poplar sawdust xylan for production of XOS and xylose by a GH11 endo-1,4-β-xylanase MxynB-8 and a GH39 β-xylosidase Xln-DT. MxynB-8 showed excellent ability to hydrolyze hemicellulose of broadleaf plants, such as poplar. Under optimized conditions (50°C, pH 6.0, dosage of 500 U/g, substrate concentration of 2 mg/mL), the final XOS yield was 85.5%, and the content of XOS2−3 reached 93.9% after 18 h. The enzymatic efficiency by MxynB-8 based on the poplar sawdust xylan in the raw material was 30.5%. Xln-DT showed excellent xylose/glucose/arabinose tolerance, which is applied as a candidate to apply in degradation of hemicellulose. In addition, the process and enzymatic mode of poplar sawdust xylan with MxynB-8 and Xln-DT were investigated. The results showed that the enzymatic hydrolysis yield of poplar sawdust xylan was improved by adding Xln-DT, and a xylose-rich hydrolysate could be obtained at high purity, with the xylose yield of 89.9%. The enzymatic hydrolysis yield was higher (32.2%) by using MxynB-8 and Xln-DT together. This study provides a deep understanding of double-enzyme synergetic enzymolysis of wood polysaccharides to valuable products.