Decrystallization Of Cellulose Research Articles

Lytic polysaccharide monooxygenase activity increases productive binding capacity of cellobiohydrolases on cellulose

Cellobiohydrolases are crucial for cellulose breakdown, but their efficiency on crystalline cellulose is hampered by limited access to single chain ends to initiate hydrolysis. As a result, they depend on enzymes like lytic polysaccharide monooxygenases (LPMOs), which directly target the crystalline cellulose surface. This study investigated how LPMO pretreatment affected the productive binding capacity of a Trichoderma longibrachiatum cellobiohydrolase, TlCBHI, on crystalline cellulose by applying an amperometric cellobiose dehydrogenase biosensor. After the 24-hour of LPMO pretreatment, the productive binding capacity of TlCBHI significantly increased in all reactions. However, with a shorter 5-hour LPMO pretreatment, minimal to no effect on productive binding capacity was observed. Of note, all LPMO reactions were inactivated around this time point. This delayed LPMO effect suggests that the improved binding capacity for cellulases does not directly result from cellulose chain cleavage by LPMOs but rather from the cellulose decrystallization following the oxidative cleavage.

Thermoplastic translucent film from wood and fatty acids by solvent free esterification: Influence of fatty acid chain length

Transforming wood into thermoplastic material has long been a challenging research topic, nevertheless the application of this technology to the industrial level hampered because of the complex method available. Here, we demonstrate a promising method converting spruce sawdust into thermoplastic material by esterification with various fatty acids of different chain length (4–18 carbon). The esterification was carried out using trifluoroacetic anhydride (TFAA) as a promoter. Weight percentage gain (WPG) of 70% was obtained for the shortest fatty acid used in this study (C4) and increased with the length of fatty acid chain to 271.3% (C18) and ester content were uniformly achieved ranged between 9.10 and 11.27 mmol/gram of wood. Chemical analysis by FTIR and CP/MAS 13C NMR revealed hydroxyl group of esterified wood was replaced by the ester group and alkyl chain. XRD analysis showed decrystallization of cellulose in esterified spruce sawdust. Esterified wood exhibit higher thermal stability observed by TGA and DSC, and presented several softening temperatures observed by TMA. Thermoplastic, translucent, and flexible film were obtained after hot pressing. In contrast with previous research, our study revealed that thermoplastic wood sheet could be obtained by esterification without solvent and at room temperature after only 4 h of reaction.

Time-Dependent Development of Mesoporosity in Ionic Liquid Treated Cellulosic Materials

Natural Fiber Welding (NFW) is process that leverages the unique solvating power of ionic liquids (IL) to mobilize a natural fiber’s outermost polymer strands and enable these mobile polymers to reconfigure and interact with mobilized polymers of adjacent fibers. Upon removal of the ionic liquid via a solvent exchange and drying process, the biopolymer material is welded into a new matrix while still maintaining the vast majority of its native structural hierarchy. Recent work in our laboratory has shown relatively simple modifications to the NFW process can drastically impact the modified matrix morphology, particularly regarding surface structure. Changes in polarity during the solvent exchange process, for instance, can be used to very the surface area over a 1000-fold and produce high surface are materials with tunable mesoporosity. In the present work we investigate the impact of variable ionic liquid treatment time on the development of mesoporosity in fiber welded cotton substrates. Nitrogen gas adsorption/desorption measurements were employed to evaluate changes in surface area and pore size with ionic liquid treatment time. Raman spectroscopy was carried out on epoxy potted material cross sections to assess the impact of treatment time on cellulose decrystallization, and epoxy penetration measured by Raman spectroscopy was used to evaluate the continuity of the mesoporous regions and further asses material porosity.

A novel accessory protein ArCel5 from cellulose-gelatinizing fungus Arthrobotrys sp. CX1

Improved understanding of cellulose swelling mechanism is beneficial for increasing the hydrolysis efficiency of cellulosic substrates. Here, we report a family 5 glycoside hydrolase ArCel5 isolated from the cellulose-gelatinizing fungus Arthrobotrys sp. CX1. ArCel5 exhibited low specific hydrolysis activity and high cellulose swelling capability, which suggested that this protein might function as an accessory protein. Homology modeling glycosylation detection revealed that ArCel5 is a multi-domain protein including a family 1 carbohydrate-binding module, a glycosylation linker, and a catalytic domain. The adsorption capacity, structural changes and hydrature index of filter paper treated by different ArCel5 mutants demonstrated that CBM1 and linker played an essential role in recognizing, binding and decrystallizing cellulosic substrates, which further encouraged the synergistic action between ArCel5 and cellulases. Notably, glycosylation modification further strengthened the function of the linker region. Overall, our study provides insight into the cellulose decrystallization mechanism by a novel accessory protein ArCel5 that will benefit future applications.Graphical

A novel decrystallizing protein CxEXL22 from Arthrobotrys sp. CX1 capable of synergistically hydrolyzing cellulose with cellulases

A novel expansin-like protein (CxEXL22) has been identified and characterized from newly isolated Arthrobotrys sp. CX1 that can cause cellulose decrystallization. Unlike previously reported expansin-like proteins from microbes, CxEXL22 has a parallel β-sheet domain at the N terminal, containing many hydrophobic residues to form the hydrophobic surface as part of the groove. The direct phylogenetic relationship implied the genetic transfers occurred from nematode to nematicidal fungal Arthrobotrys sp. CX1. CxEXL22 showed strong activity for the hydrolysis of hydrogen bonds between cellulose molecules, especially when highly crystalline cellulose was used as substrate. The hydrolysis efficiency of Avicel was increased 7.9-fold after pretreating with CxEXL22. The rupture characterization of crystalline region indicated that CxEXL22 strongly binds cellulose and breaks up hydrogen bonds in the crystalline regions of cellulose to split cellulose chains, causing significant depolymerization to expose much more microfibrils and enhances cellulose accessibility.

Prediction of power of a vibration rod mill during cellulose decrystallization processing by DEM

The crystallinity index of cellulose decrystallized with a vibration rod mill was well correlated with input energy of the vibration rod mill. In order to predict the energy, rod behavior was simulated by discrete element method (DEM).Decrystallization of cellulose was performed using a vibration rod mill to increase the reactivity. The decrystallization speed increased with an increase in the number of rods and the crystallinity index of cellulose after pulverization can be uniquely identified by the input energy [kWh/kg], which is actual power times pulverization time divided by cellulose mass charged into the vibration rod mill. Therefore, the actual power of the vibration rod mill was calculated using DEM simulation, wherein rods were constructed by connecting spherical particles using the multi-sphere method. The coefficients of friction and restitution were determined based on the movement of the rod in the mill cylinder from the experiments. The power calculated agrees with the actual power. This study suggests that the power of the vibration rod mill can be predicted using DEM and that the crystallinity index can be predicted without experimentation.

Improving enzymatic saccharification and ethanol production of bamboo residues with sulfomethylation-aided phosphoric acid pretreatment

The sulfomethylation-aided phosphoric acid pretreatment (SPAP) was investigated for bamboo biorefinery. The yield of glucose and xylose were increased from 19.8 % and 13.88 % for H3PO4-pretreated D. sinicus alone (PAP-DS) to 89.06 % and 72.92 % for SPAP-DS. Ethanol concentration for SPAP-DS was 13.26 g/L, which improved by about 3-folds than PAP-DS. The SPAP-DS exhibited the lower lignin content and cellulose crystallinity, thus resulting in the enzyme accessibility to cellulose increased remarkably. The pre-step of sulfomethylation loosened compact structure of bamboo, which significantly contributed to the decrystallization of cellulose in the following H3PO4-pretreatment. The study has potential implications in biomass pretreatments, which should target synergistically and simultaneously toward cellulose, hemicellulose, or lignin fraction for obtaining higher bio-based chemical compounds and biofuels.

Cellulose Recovery from Agri-Food Residues by Effective Cavitational Treatments

Residual biomass from agri-food production chain and forestry are available in huge amounts for further valorisation processes. Delignification is usually the crucial step in the production of biofuels by fermentation as well as in the conversion of cellulose into high added-value compounds. High-intensity ultrasound (US) and hydrodynamic cavitation (HC) have been widely exploited as effective pretreatment techniques for biomass conversion and in particular for cellulose recovery. Due to their peculiar mechanisms, cavitational treatments promote an effective lignocellulosic matrix dismantling with delignification at low temperature (35–50 °C). Cavitation also promotes cellulose decrystallization due to a partial depolymerization. The aim of this review is to highlight recent advances in US and HC-assisted delignification and further cellulose recovery and valorisation.

Kinetics of ionic liquid-facilitated cellulose decrystallization by Raman spectral mapping

The decrease in crystallinity of a cotton thread upon exposure to the ionic liquid 1-ethyl-3-methylimidazolium acetate is investigated via two-dimensional Raman spectral mapping of the thread cross-section. By monitoring an intrinsic cellulose I Raman mode, the transition from highly crystalline cellulose I to amorphous cellulose is monitored as a function of treatment time and temperature. At extended treatment times, a heterogeneous decrystallization occurs where only those fibers at the outer edge of the thread decrystallize and dissolve while fibers in the thread center exhibit a constant crystallinity. As a result, a large amorphous cellulose shell develops which surrounds a central bundle of still-distinct and highly crystalline cotton fibers. Observed trends in the temperature-dependent rate of heterogeneous thread decrystallization are attributed to a transition to diffusion-limited decrystallization associated with the development of a solvent-swollen amorphous polymer layer. Raman spectral mapping provides new opportunities to investigate the effect of treatment conditions on the spatial extent and degree of crystallinity as well as the mechanism of decrystallization in cellulose biopolymer materials.

Decrystallization Kinetics of Cotton Yarns in Ionic Liquids – Raman Spectral Mapping

Ionic liquids (ILs) are promising solvents for the treatment and processing of cellulosic biopolymer materials. Despite the discovery of numerous ILs capable of dissolving varying amounts of cellulose, a detailed understanding of the dissolution process in ILs is still lacking. In this study, a new approach, Raman spectral mapping, is employed to investigate the kinetics of cellulose decrystallization and dissolution in a prototypical solvent IL, 1-ethyl-3-methylimidazolium acetate. The cellulose utilized is in the form of mercerized cotton yarns. By monitoring Raman bands characteristic of the crystalline domains, we investigate the degree and spatial extent of crystallinity in IL treated yarns. To elucidate the interplay of kinetic (viscosity) and thermodynamic (solvation) factors in the decrystallization process, the treatment time and temperature were systematically varied. A detailed analysis of the experimental results reveals three distinct temperature-dependent decrystallization regimes including (i) homogeneous decrystallization and cotton yarn collapse, (ii) fast-heterogeneous decrystallization of the collapsed yarn, and (iii) slow heterogeneous decrystallization. These results are discussed within the framework of the current understanding of cellulose and polymer dissolution.

Ball milling promotes saccharification of agricultural biomass by heteropolyacid and enzyme: unlock the lignin cage for sugars recovery

An integrative process for efficient saccharification of hemicellulose and cellulose components from lignocellulosic biomass is of strategic significance for a sustainable society. Raw carbohydrate-lignin matrix demonstrates low reactivity due to existence of crystalline zones and lignin inhibition. To overcome these obstacles, the process synergistically integrating ball milling, heteropolyacid as well as enzymatic hydrolysis, is proposed to unlock the lignin cage for sugars releasing. Among these gathered technologies, ball milling is an alternative pretreatment method for decrystallization of cellulose in bamboo shoot shell (BSS), endowing cellulose I with 71.3% crystallinity index (CrI) to cellulose II with 9.5% CrI accompanying particles decreasing from 283 to 29 μm in D50 size. Under the optimum condition, phosphotungstic acid (HPW) hydrolysis at 150 °C for 2.0 h and subsequently enzymatic hydrolysis at 50 °C for 7.0 h, the results indicate that BSS milled without HPW obtains 763.6 mg/g of monomeric sugars, employing 0.7 gHPW/gsubstrate while BSS milled with 2.5% HPW can achieve 741.6 mg/g of monomeric sugars but only employing 0.1 gHPW/gsubstrate in reaction. This integrative strategy provides a good guidance for promoting the conversion of raw lignocellulosic biomass to monosaccharides in high efficiency.

Decrystallization of cellulose under the influence of elastomer-assisted mechanical and mechanochemical shear

Microcrystalline cellulose (MCC) was subjected to mechanical and mechanochemical shear in a rubber mixing milling. Nitrile rubber (NBR) and ethylene–propylene–diene monomer (EPDM) rubber were used to induce shear on cellulose during treatment. Solid-state interactions between N,$$N^\prime $$-dimethylacetamide/lithium chloride (DMAc/LiCl) and cellulose particles were facilitated during mechanochemical shear. Fourier transform infrared spectroscopy, X-ray diffraction analysis, thermogravimetric analysis, scanning electron microscopy and swelling studies were carried out on MCC, DMAc/LiCl-treated MCC, MCC subjected to mechanical shear and DMAc/LiCl-treated MCC subjected to mechanochemical shear. Crystallinity and swelling behaviour of the untreated and merely DMAc/LiCl-treated MCC samples, in the absence of any shear, were found to be similar. However, when MCC was subjected to mechanical shear assisted by NBR and DMAc/LiCl-treated MCC subjected to mechanochemical shear assisted by EPDM, the resultant MCC samples exhibited significant reduction in their crystalline index with increased swelling. When DMAc/LiCl-treated MCC was subjected to mechanochemical shear assisted by NBR and mechanical shear alone on MCC, assisted by EPDM, did not exhibit any appreciable change in the crystalline index and swelling behaviour of the resultant MCC samples. While NBR-assisted mechanical shear was found to reduce crystallinity in untreated MCC, crystallinity in DMAc/LiCl-treated MCC was found to be reduced significantly with EPDM rubber-assisted mechanochemical shear.

Cellulose nanosheets formed by mild additive-free ball milling

Cellulose nanosheets similar to those obtained by milling with silicone oil (Zhao et al. in Cellulose 23:2809–2818, 2016) were obtained by mild additive-free milling followed by dispersion in ethanol. Typical nanosheets were of 4 nm thickness, possibly formed by monolayer association of elementary fibrils. The thickness decreased with prolonged milling to 2 nm or less, and the thinnest sheets observed were about 0.4 nm, corresponding to monomolecular layer of cellulose. Further milling caused disappearance of nanosheets due to complete decrystallization. This observation indicates that nanosheet formation is an intermediate stage of decrystallization of cellulose.

Reaction engineering implications of cellulose crystallinity and water-promoted recrystallization

Mechanical decrystallization and water-promoted recrystallization of cellulose were studied to understand the effects of cellulose crystallinity on reaction engineering models of its acid-catalyzed hydrolysis.

Double-adsorption functional carbon based solid acids derived from copyrolysis of PVC and PE for cellulose hydrolysis

High value-added utilization of plastic waste has historically been a problem, which has driven researchers to make long-term and unremitting efforts to tackle it. High-performance carbon based solid acid (CSA) was prepared from polyvinyl chloride (PVC) and polyethylene (PE) in different proportions. The small amount of chlorine is still residual on the edge of graphitic carbon sheets after co-carbonization and sulfonation. Strong electronegative –Cl group and the high-density phenolic –OH group, double-adsorption group, are covalently bonded to the edges of the graphitic carbon sheets, contributing to the decrystallization of cellulose to a large extent. Meanwhile, PVC and PE-derived CSAs have significantly higher –SO3H group density than PVC-derived CSA and cellulose-derived CSA. These are obviously beneficial to the improvement of hydrolysis activity, which can be attributed to structural optimization caused by co-carbonization PVC and PE. The CSA with a mixture of 80% proportions has great catalytic activity and repeatability.

Cellulose modification by recyclable swelling solvents

BackgroundThe invention of efficient systems for lignocellulose conversion is essential for economically feasible production of bio-based chemicals and biofuels. One limiting step is highly selective processes to quickly decrystallize the compact cellulose structure for efficient hydrolysis. We evaluated the impact of trifluoroacetic acid (TFA) and phosphorous acid (PA)-induced swelling of crystalline cellulose on enhancement of enzymatic digestion.ResultsIn this study, two swelling agents, TFA and PA, are compared and found to be highly efficient for cellulose decrystallization at low temperatures within 1 h. After treatment, the microfibril structure of swollen celluloses was observed to develop distinct microscopic morphology and subsequent enzymatic hydrolysis resulted over 90% cellulose conversion within 24 h. The crystalline cellulose change was determined by reduction of loss of X-ray diffractability, and loss of resistance to enzymatic hydrolysis. NMR results suggest that both TFA and PA efficiently converted most of the crystalline cellulose regions to amorphous regions through cellulose chain relocation that inhibits recrystallization. It was found that the swelling mechanism is different between TFA and PA. To the best of our knowledge, it is the first time to compare and quantify the cellulose regions transformation by swelling agents.ConclusionThis study shows the low-temperature swelling of different celluloses in TFA and PA reduces recalcitrance of crystalline cellulose to enzymatic hydrolysis. TFA and PA are both ideal candidate swelling agents for a closed system for ease of solvent recovery by either simple distillation or filtration. This study provides potentially useful agents in large-scale deconstruction of biomass.

Effects of Enzymatic Hydrolysis on the Physicochemical and Structural Properties of Cassava Bagasse (<em>Manihot esculenta Cranz</em>).

This study evaluated the effect of enzymatic hydrolysis on the physicochemical and structural properties of cassava bagasse ( Manihot esculenta Cranz ). Cassava bagasse is a byproduct of the cassava starch process with limited applications in the industry. Were applied enzymatic treatments to three ratios a substrate (cassava bagasse): Buffer volume (1:10, 1:15, 1:20). Were used two commercial enzymes, cellulase (CelluSEB TL) and α-amylase (Licquozyme supra 2.2X). The physicochemical and structural analysis was performed after each treatment, including a control. The physicochemical analysis showed that the cassava bagasse had a high content of carbohydrates (61,19%) and fiber (22,63%); additionally, there were significant differences (p -1 corresponding to the cellulose chemical bond CH, as well as the decrease in the intensity of the band 2927 cm-1 corresponding to the CH bonds and CH2, which may be related to a decrease of the crystallinity in the enzymatically treated bagasse. It was found that, due to its physicochemical composition, cassava bagasse is a material that could be used for biotechnology or food purposes; moreover, enzymatic hydrolysis produces the decrystallization of cellulose and significant changes in its physicochemical properties.

Identification and Characterization of a Large Protein Essential for Degradation of the Crystalline Region of Cellulose by Cytophaga hutchinsonii.

Cytophaga hutchinsonii could efficiently degrade crystalline cellulose with a unique mechanism without cellulosomes and free cellulases. It lacks proteins that are thought to play important roles in disruption of the crystalline region of cellulose, including exoglucanases, lytic polysaccharide monooxygenases, expansins, expansin-like proteins, or swollenins, and most of its endoglucanases lack carbohydrate binding modules. The mechanism of the degradation of crystalline cellulose is still unknown. In this study, chu_3220 was identified as the first gene essential for the degradation of the crystalline region but not the amorphous region of cellulose. CHU_3220 is a high-molecular-weight protein located on the outer surface of the outer membrane and could bind to cellulose. We proposed that CHU_3220 might be an essential component of a protein complex on the cell surface in charge of the decrystallization of crystalline cellulose. The degradation of crystalline cellulose by C. hutchinsonii was not only dependent on intact cells but also required the energy supplied by the cells. This was obviously different from other known cellulose depolymerization system. Our study has shed more light on the novel strategy of crystalline cellulose degradation by C. hutchinsonii.

Cellulose dissolution: insights on the contributions of solvent-induced decrystallization and chain disentanglement

The dissolution of cellulose is a critical step for the efficient utilization of this renewable resource as a starting material for the synthesis of high value-added functional polymers and chemicals and also for biofuel production. The recalcitrance of semicrystalline cellulose microfibrils presents a major barrier to cellulose dissolution. Despite research efforts, important aspects of cellulose dissolution such as solvent-induced decrystallization and chain disentanglement are not well-understood. Here we address these fundamental issues with the practical goal of gaining insights into the swelling and dissolution of cellulose that cannot be obtained from macroscopic experimental data. To this end, we have used a newly-developed phenomenological model that captures the phenomena governing the dissolution of semicrystalline polymers as well as the thermodynamics and kinetics of dissolution. This model fits well experimental data for swelling and dissolution of cotton fibers in the ionic liquid [bmim]Cl, and allows the quantification of two important aspects, i.e., solvent effectiveness in cellulose (1) decrystallization and (2) chain disentanglement, the balance of which controls the mechanism and kinetics of cellulose dissolution. The activation parameters of cellulose decrystallization, estimated using the obtained decrystallization constant values, reveal that the decrystallization of cellulose in [bmim]Cl is associated with positive enthalpy and entropy and it is also very sensitive to temperature. When the solvent effectiveness in the disruption of cellulose crystals is relatively lower than its ability to disentangle the chains, the kinetics of dissolution are controlled by decrystallization. Furthermore, conditions that facilitate cellulose chain disentanglement, in addition to increasing the rate of dissolution, can result in faster decrystallization. The solvent effectiveness in chain disentanglement is the only factor that determines the decrease of the cellulose fiber radius. In cases where the fiber dissolution rate is lower than the decrystallization rate, the dissolution of cellulose is mostly controlled by the solvent ability to disentangle the chains. The insights obtained from this study improve the understanding of cellulose–solvent interactions underlying decrystallization and disentanglement and their contributions in controlling the kinetics of cellulose swelling and dissolution.

Gelatinization and decrystallization of cellulose by newly isolated Arthrobotrys sp. CX1 to facilitate cellulose degradability

A nematicidal fungus strain was isolated and identified as a novel member of the genus Arthrobotrys based on the morphologic and phylogenetic analysis and designed as CX1. Strain CX1 could make the filter paper translucent, resulting in an increasing hydrature index by 73.7 % and a reducing crystalline index by 32 % in comparison with the untreated filter paper. Scanning electron microscopy showed swollen microfibrils in the presence of water, and Fourier transformed infrared spectroscopy indicated the change in absorbance and/or wavenumber for hydrogen bonds. The cellulose degradability was increased by 3.5 times when the filter paper was treated with Arthrobotrys sp. CX1 but no cellulase activities could be detected in the culture supernatant of strain CX1. The isolate CX1 could gelatinize the filter paper cellulose causing decrystallization with high water imbibition. It is significant to apply it to the initial cellulose deconstruction to facilitate the cellulose saccharification.