- CHARACTERIZATION OF MONO- AND OLIGOSACCHARIDES PRODUCED BY CO2 LASER IRRADIATION ON CELLULOSE
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The chemical structures of three mono-, two di-, and two trisaccharides (1 - 7) isolated from the pyrolysis products formed by CO2 laser irradiation on cellulose were investigated.
- Suzuki, Jun,Azuma, Jun-ichi,Koshijima, Tetsuo,Okamura, Keizo,Okamoto, Hajime
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- Glucose production from saccharides using layered transition metal oxide and exfoliated nanosheets as a water-tolerant solid acid catalyst
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The layered transition-metal oxide HNbMoO6 is demonstrated to exhibit remarkable catalytic performance for the hydrolysis of saccharides such as sucrose, cellobiose, starch, and cellulose, attributable to water tolerance and the facile accessibility of saccharides into the strong acidic interlayer gallery of the solid. The Royal Society of Chemistry.
- Takagaki, Atsushi,Tagusagawa, Caio,Domen, Kazunari
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- Biochemical characterization and low-resolution SAXS structure of two-domain endoglucanase BlCel9 from Bacillus licheniformis
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Lignocellulose feedstock constitutes the most abundant carbon source in the biosphere; however, its recalcitrance remains a challenge for microbial conversion into biofuel and bioproducts. Bacillus licheniformis is a microbial mesophilic bacterium capable of secreting a large number of glycoside hydrolase (GH) enzymes, including a glycoside hydrolase from GH family 9 (BlCel9). Here, we conducted biochemical and biophysical studies of recombinant BlCel9, and its low-resolution molecular shape was retrieved from small angle X-ray scattering (SAXS) data. BlCel9 is an endoglucanase exhibiting maximum catalytic efficiency at pH?7.0 and 60?°C. Furthermore, it retains 80% of catalytic activity within a broad range of pH values (5.5–8.5) and temperatures (up to 50?°C) for extended periods of time (over 48?h). It exhibits the highest hydrolytic activity against phosphoric acid swollen cellulose (PASC), followed by bacterial cellulose (BC), filter paper (FP), and to a lesser extent carboxymethylcellulose (CMC). The HPAEC-PAD analysis of the hydrolytic products demonstrated that the end product of the enzymatic hydrolysis is primarily cellobiose, and also small amounts of glucose, cellotriose, and cellotetraose are produced. SAXS data analysis revealed that the enzyme adopts a monomeric state in solution and has a molecular mass of 65.8?kDa as estimated from SAXS data. The BlCel9 has an elongated shape composed of an N-terminal family 3 carbohydrate-binding module (CBM3c) and a C-terminal GH9 catalytic domain joined together by 20 amino acid residue long linker peptides. The domains are closely juxtaposed in an extended conformation and form a relatively rigid structure in solution, indicating that the interactions between the CBM3c and GH9 catalytic domains might play a key role in cooperative cellulose biomass recognition and hydrolysis.
- de Araújo, Evandro Ares,de Oliveira Neto, Mário,Polikarpov, Igor
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- Analysis of mono- and oligosaccharides in ionic liquid containing matrices
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Ionic liquids (ILs), that is, salts with melting points 100 °C, have recently attracted a lot of attention in biomass processing due to their ability to dissolve lignocellulosics. In this work, we studied how two imidazolium-based, hydrophilic, cellulose dissolving ionic liquids 1,3-dimethylimidazolium dimethylphosphate [DMIM]DMP and 1-ethyl-3- methylimidazolium acetate [EMIM]AcO affect the usually employed analytical methods for mono- and oligosaccharides, typical products from hydrolytic treatments of biomass. HPLC methods were severely hampered by the presence of ILs with loss of separation power and severe baseline problems, making their use for saccharide quantification extremely challenging. Problems in DNS photometric assay and chromatography were also encountered at high ionic liquid concentrations and many capillary electrophoresis (CE) methods did not allow an efficient analysis of saccharides in these matrices. In this paper we describe an optimized CE method with pre-column derivatization for the qualitative and quantitative analysis of mono- and oligosaccharides in sample matrices containing moderate (20-40% (v/v)) concentrations of ILs. The IL content and type in the sample matrix was found to affect both peak shape and quantification parameters. Generally, the presence of high IL concentrations (≥20% (v/v)) had a dampening effect on the detection of the analytes. IL in lower concentrations of 20% (v/v) was, however, found to improve peak shape and/or separation in some cases. The optimized CE method has good sensitivity in moderate concentrations of the ionic liquids used, with limits of detection of 5 mg/L for cellooligomers up to the size of cellotetraose and 5-20 mg/L for cellopentaose and cellohexaose, depending on the matrix. The method was used for analysing the action of a commercial β-glucosidase in ILs and for analysing saccharides in the IL containing hydrolysates from the hydrolysis of microcrystalline cellulose with Trichoderma reesei endoglucanase Cel5A. According to the results, [DMIM]DMP and [EMIM]AcO] showed clear differences in enzyme inactivation.
- Wahlstr?m, Ronny,Rovio, Stella,Suurn?kki, Anna
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- Ionic liquid tolerant hyperthermophilic cellulases for biomass pretreatment and hydrolysis
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One of the main barriers to the enzymatic hydrolysis of cellulose results from its highly crystalline structure. Pretreating biomass with ionic liquids (IL) increases enzyme accessibility and cellulose recovery through precipitation with an anti-solvent. For an industrially feasible pretreatment and hydrolysis process, it is necessary to develop cellulases that are stable and active in the presence of small amounts of ILs co-precipitated with recovered cellulose. However, a significant decrease in cellulase activity in the presence of trace amounts of ILs has been reported in the literature, necessitating extensive processing to remove residual ILs from the regenerated cellulose. Towards that end, we have investigated the stability of hyperthermophilic enzymes in the presence of the IL 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) and compared it to the industrial benchmark Trichoderma viride (T. viride) cellulase. The endoglucanase from a hyperthermophilic bacterium, Thermatoga maritima, and a hyperthermophilic archaeon, Pyrococcus horikoshii, were over expressed in E. coli and purified to homogeneity. Under their optimum conditions, both hyperthermophilic enzymes showed significantly higher [C2mim][OAc] tolerance than T. viride cellulase. Using differential scanning calorimetry we determined the effect of [C2mim][OAc] on protein stability and our data indicates that higher concentrations of IL correlated with lowered protein stability. Both hyperthermophilic enzymes were active on [C2mim][OAc] pretreated Avicel and corn stover. Furthermore, these enzymes can be recovered with little loss in activity after exposure to 15% [C2mim][OAc] for 15 h. These results demonstrate the potential of using IL-tolerant extremophilic cellulases for hydrolysis of IL-pretreated lignocellulosic biomass, for biofuel production.
- Datta, Supratim,Holmes, Bradley,Park, Joshua I.,Chen, Zhiwei,Dibble, Dean C.,Hadi, Masood,Blanch, Harvey W.,Simmons, Blake A.,Sapra, Rajat
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- Carbon Materials as Phase-Transfer Promoters for Obtaining 5-Hydroxymethylfurfural from Cellulose in a Biphasic System
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Different carbonaceous materials were tested as mass-transfer promoters for increasing the yield of 5-hydroxymethylfurfural (5-HMF) in biphasic cellulose hydrolysis. The benefits of working with a biphasic system (water/methyl isobutyl ketone) under soft acid conditions were taken as starting point (no humins or levulinic acid production), with slow extraction kinetics as the weakest point of this approach. Carbon nanotubes (CNTs) and activated carbon (AC) were proposed to improve 5-HMF liquid–liquid mass transfer. A kinetic analysis of the extraction process indicated the competition between 5-HMF and glucose adsorption as the main cause of the poor results obtained with AC. In contrast, very promising results were obtained with CNTs, mainly at 1.5 wt % loading, with complete transfer of HMF and a high global mass-transfer coefficient. The use of CNTs improved the amount of 5-HMF in the organic phase by more than 270 %.
- Faba, Laura,Garcés, Diego,Díaz, Eva,Ordó?ez, Salvador
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p. 3769 - 3777
(2019/07/04)
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- Hydrolysis behaviors of sugarcane bagasse pith in subcritical carbon dioxide-water
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The aim of this study was to describe the hydrolysis behavior of sugarcane bagasse pith (SCBP) in subcritical CO2-water. The hydrolysis was carried out in a batch reactor using different temperatures (160 to 260 °C), liquid to solid ratios (20:1 to 100:1), CO2 pressures (0 to 7.3 MPa), stirring speeds (0 to 500 rpm) and reaction times (0 to 40 min). The highest total reducing sugar yield (43.6%) was obtained at 200 °C, liquid to solid ratio 30:1, 2 MPa CO2, 500 rpm and 50 min. Two-dimensional heteronuclear single quantum coherence (2D HSQC) nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FT-IR) were used to help elucidate the physical and chemical characteristics of the raw material and residual solid particles, with results consistent with the removal of hemicellulose during hydrolysis. The changes in the concentration of products with time were analyzed to understand product distribution through high-performance liquid chromatography (HPLC) and to infer the reaction mechanism.
- Liang, Jiezhen,Chen, Xiaopeng,Wang, Linlin,Wei, Xiaojie,Qiu, Feifei,Lu, Chaochao
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p. 99322 - 99330
(2016/11/02)
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- Optimization and hydrolysis of cellulose under subcritical water treatment for the production of total reducing sugars
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Subcritical water (SCW) treatment has gained enormous attention as an environmentally friendly technique for organic matter and an attractive reaction medium for a variety of applications. In this work, hydrolysis of cellulose was studied under SCW conditions in a batch reactor to attain total reducing sugars (TRS) within a reaction temperature and time range of 150 to 250 °C and 10-60 min, respectively. From the experimental results, the highest yield of TRS was 45.04% as obtained at 200 °C and 20 min of hydrolysis time. The characterisation techniques, namely X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were used as to determine the structural and compositional changes in the hydrolysed material. Reaction parameters such as temperature, time, and solute loading have been optimised using response surface methodology based on a central composite design. From ANOVA analysis, it was described that the second-order response surface model is highly significant as per Fisher's F-test and P-value. A first-order reaction kinetic model was formulated to describe the hydrolysis of cellulose for TRS formation and decomposition. For TRS formation, the activation energy and pre-exponential factor of the Arrhenius equation was found to be 29.16 kJ mol-1 and 0.088 min-1 for 60 min, respectively.
- Mohan, Mood,Timung, Robinson,Deshavath, Narendra Naik,Banerjee, Tamal,Goud, Vaibhav V.,Dasu, Venkata V.
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p. 103265 - 103275
(2015/12/23)
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- Supercritical water treatment for cello-oligosaccharide production from microcrystalline cellulose
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Microcrystalline cellulose was treated in supercritical water at 380 °C and at a pressure of 250 bar for 0.2, 0.4, and 0.6 s. The yield of the ambient-water-insoluble precipitate and its average molar mass decreased with an extended treatment time. The highest yield of 42 wt % for DP2-9 cello-oligosaccharides was achieved after the 0.4 s treatment. The reaction products included also 11 wt % ambient-water-insoluble precipitate with a DPw of 16, and 6.1 wt % monomeric sugars, and 37 wt % unidentified degradation products. Oligo- and monosaccharide-derived dehydration and retro-aldol fragmentation products were analyzed via a combination of HPAEC-PAD-MS, ESI-MS/MS, and GC-MS techniques. The total amount of degradation products increased with treatment time, and fragmented (glucosyln-erythrose, glucosyln-glycolaldehyde), and dehydrated (glucosyln-levoglucosan) were identified as the main oligomeric degradation products from the cello-oligosaccharides.
- Tolonen, Lasse K.,Juvonen, Minna,Niemel?, Klaus,Mikkelson, Atte,Tenkanen, Maija,Sixta, Herbert
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- Mass spectrometric studies of fast pyrolysis of cellulose
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A fast pyrolysis probe/linear quadrupole ion trap mass spectrometer combination was used to study the primary fast pyrolysis products (those that first leave the hot pyrolysis surface) of cellulose, cellobiose, cellotriose, cellotetraose, cellopentaose, and cellohexaose, as well as of cellobiosan, cellotriosan, and cellopentosan, at 600°C. Similar products with different branching ratios were found for the oligosaccharides and cellulose, as reported previously. However, identical products (with the exception of two) with similar branching ratios were measured for cellotriosan (and cellopentosan) and cellulose. This result demonstrates that cellotriosan is an excellent small-molecule surrogate for studies of the fast pyrolysis of cellulose and also that most fast pyrolysis products of cellulose do not originate from the reducing end. Based on several observations, the fast pyrolysis of cellulose is suggested to initiate predominantly via two competing processes: The formation of anhydro-oligosaccharides, such as cellobiosan, cellotriosan, and cellopentosan (major route), and the elimination of glycolaldehyde (or isomeric) units from the reducing end of oligosaccharides formed from cellulose during fast pyrolysis.
- Degenstein, John C.,Hurt, Matt,Murria, Priya,Easton, McKay,Choudhari, Harshavardhan,Yang, Linan,Riedeman, James,Carlsen, Mark S.,Nash, John J.,Agrawal, Rakesh,Nicholas Delgass,Ribeiro, Fabio H.,Kentt?maa, Hilkka I.
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p. 321 - 326
(2016/03/25)
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- Capillary electrophoretic monitoring of hydrothermal pre-treatment and enzymatic hydrolysis of willow: Comparison with HPLC and NMR
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The resurgence of the research of biomass processing is demanding novel methods facilitating the monitoring of lignocellulose processing. Here we demonstrate the suitability of capillary electrophoresis (CE) in the analysis of hydrothermal pre-treatment a
- Vaher, Merike,Helmja, Kati,K?sper, Andres,Kura?in, Mihhail,V?ljam?e, Priit,Kudrja?ova, Marina,Koel, Mihkel,Kaljurand, Mihkel
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