Green synthesis of xylan hemicellulose esters (original) (raw)
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Production of D-xylonic acid from hemicellulose using artificial enzyme complexes
Journal of microbiology and biotechnology, 2016
Lignocellulosic biomass represents a potentially large resource to supply the world's fuel and chemical feedstocks. Enzymatic bioconversion of this substrate offers a reliable strategy for accessing this material under mild reaction conditions. Due to the complex nature of lignocellulose, many different enzymatic activities are required to function in concert to perform efficient transformation. In nature, large multienzyme complexes are known to effectively hydrolyze lignocellulose into constituent monomeric sugars. We created artificial complexes of enzymes, called rosettazymes, in order to hydrolyze glucuronoxylan, a common lignocellulose component, into its cognate sugar D-xylose and then further convert the D-xylose into D-xylonic acid, a DOE top-30 platform chemical. Four different types of enzymes (endoxylanase, α- glucuronidase, β-xylosidase, and xylose dehydrogenase) were incorporated into the artificial complexes. We demonstrated that tethering our enzymes in a complex...
Hemicellulose-derived chemicals: one-step production of furfuryl alcohol from xylose
Green Chemistry, 2014
One-pot production of furfuryl alcohol via xylose dehydration followed by furfural hydrogenation was investigated over a dual catalyst system composed of Pt/SiO 2 and sulfated ZrO 2 as metal and acid catalysts, respectively. All samples were characterized by XRD, XRF, N 2 physisorption, TG-MS and FTIR regarding their most fundamental properties for the studied process. A systematic study is reported on the effects of the reaction temperature, the composition of the binary solvent and the molar ratio between acid and metal sites in the catalyst system. The results revealed the feasibility of the one-step process for furfuryl alcohol synthesis and showed that the occurrence of both acid and metal sites is compulsory in order to promote the dehydration of xylose to furfural and its further hydrogenation to furfuryl alcohol. Selectivity towards furfuryl alcohol was found to be strongly dependent on the solvent, which can inhibit its polymerization to some extent. † Electronic supplementary information (ESI) available. See
2011
Humicola lanuginosus produced xylanase 1100 U/ mL in liquid state culture at optimum condition like pH 5, temperature 35°C, inoculum size 2mL, time period 4 days, Vogel's media 160 mL, 1 g corn steep liquir as best nitrogen source using sugar cane bagasse (5g) as a substrate. Xylanase passing from gel filteration obtained with an average specific activity of 379 U/mg protein, purification fold 1.9 and recovery yield of xylanase 10%. Patially purified xylanase has optimum pH 5.0, stability range of pH 6 to 7 and optimum temperature 45°C, stability range of temperature 35 to 40°C for 24 hours incubation. Km and Vmax of partially purified xylanase oxidize xylan were obtained 2 mM, 450 mM/min. MgCl enhanced the activity of partially 2 purified xylanase but silver nitrate strongly inhibited. Crude xylanase (2-10 mL) removed the reducing sugar 20 mg/mL from rice polish as compared with lignocellulosic substrates such as rice husks, corn stover and corn cobs.
Bio-based products from xylan: A review
Carbohydrate Polymers, 2017
Obtaining chemicals and materials in sustainable ways is of growing importance. A potential source of sustainable chemicals and materials is lignocellulosic biomass residues generated as waste from agriculture. Hemicellulose which is a large component in lignocellulosic biomass residues, provides many potential applications such as the generation of chemicals, packaging materials, drug delivery and biomedical applications. This review deals with the various techniques which can be used for the extraction of hemicellulose from biomass residues, purification and some potential applications of the extracted hemicellulose. The methods that have been used to further produce chemicals from extracted hemicellulose as well as their applications are discussed.
Lenzinger …, 2009
General aspects of autohydrolysis at varied temperatures, treatment intensities and liquid-to-wood ratios were investigated. Overall solid balance of the selected samples was determined using gravimetrical methods. Analytical methods for carbohydrates and lignin were used to represent componential mass balance. Water hydrolysis activates lignin by homolytic cleavage which results in partial transfer to the hydrolysates in the form of dissolved and dispersed lignin while parts of the residue reveal an increased solubility in acetone. The amount of acetone soluble matter increases with P-factor and decreasing liquor-to-wood ratio. Moderate autohydrolysis, representing a P-factor of about 200, which might be suitable for subsequent paper pulp production releases sugar components in an amount of about 6-7% on wood, while this value increases up to 12% and more when autohydrolysis conditions are applied, P-factor~800, which are typical for dissolving pulp production. Preliminary dehydration studies with glucose as model substance at 160ºC over ZrO 2 and TiO 2 catalysts have been conducted. The objective is to develop a low-cost process for the manufacture of hydroxymethylfurfural (HMF) from C6-sugars, preferably glucose and mannose. It has been shown that ZrO 2 is slightly more effective in catalyzing isomerisation to fructose, while TiO 2 was more active in dehydration. However, both catalysts exhibit not enough acidic sites to catalyze the overall reaction effectively.
Development of an acetylation reaction of switchgrass hemicellulose in ionic liquid without catalyst
Industrial Crops and Products, 2013
Hemicellulose material is an abundant and relatively under-utilized hetero-polysaccharides material present in lignocellulosic materials. In this research, an alkaline treatment was applied to switchgrass in order to extract hemicelluloses to subsequently produce an acetylated product. An extraction at 75 • C recovered 27% of the biomass as a predominantly hemicellulose material with a number average degree of polymerization of ∼500 determined by gel permeation chromatography. These hemicelluloses were acetylated with acetic anhydride in 1-allyl-3-methylimidazolium chloride ([Amim] + Cl − ) ionic liquid in a complete homogeneous procedure without catalyst for the first time. It was determined that the yield and degree of substitution increased with reaction temperature from 30 to 80 • C and reaction time from 1 to 20 h. The product was characterized by FTIR spectroscopy, NMR, gel permeation chromatography for molecular weight and water contact angle analysis. FTIR spectroscopic analysis showed that the characteristic absorption intensities of acetylated hemicellulose increased and the hydroxyl group decreased with the increase in the degree of substitution. Increased degree of substitution increased the water contact angle and thermal stability in nitrogen. It was possible to cast films of the acetylated hemicellulose although the films were brittle. The results obtained indicate a promising combination between the effective extraction of hemicellulose from grasses and an environmentally friendly process using acetic anhydride in an ionic liquid without a catalyst to generate hemicellulose acetate with high degree of polymerization for use in various industrial applications.
Alkaline extraction and carboxymethylation of xylans from corn fiber_Cellulose_2019.pdf
Cellulose, 2019
In the corn crop industry, of all the biomass produced, about 80% are residues. The so-called corn fibers, one of the most important residues of the corn processing industry, represent about 9% of the corn kernel weight, being a low value material that could, potentially, be used for making higher added value products. This work aimed to extract the hemicelluloses present in the corn fiber via alkaline extraction, with their subsequent functionalization for production of carboxymethyl xylans in mild conditions. The corn fibers were characterized for their contents of carbohydrates, lignin, extractives, total uronic acids, acetyl groups, and ash. Their arabinoxylans were extracted by 2–18% (w/v) sodium hydroxide at room temperature, for 5 h at 10% consistency, precipitated with ethanol, washed and then vacuum dried. The resulting extract was characterized by FT-IR, viscosity, arabinoxylan content and purity. It was demonstrated that CCE treatment provides a high purity and little degraded xylan, but the extraction yields are relatively low, in the range of 4.0–23.9% wt/wt depending upon extraction conditions. The use of corn fiber arabinoxylans to obtain hemicellulosic derivatives through chemical modification reactions was also evaluated. The arabinoxylans were derivatized by carboxymethylation with sodium monochloroacetate in a 2-propanol alkaline medium using different proportions of alcohol and alkali. The product carboxymethyl xylan was characterized by degree of substitution, FT-IR, DSC, and yield, and showed high degree of substitution, yield and enthalpy of fusion. This work proved the feasibility of producing hemicellulosic derivatives from corn fibers, which excludes the use of extreme conditions of solvents and temperature.
Applied Microbiology and Biotechnology, 2014
An essential step in the conversion of lignocellulosic biomass to ethanol and other biorefinery products is conversion of cell wall polysaccharides into fermentable sugars by enzymatic hydrolysis. The objective of the present study was to understand the mode of action of hemicellulolytic enzyme mixtures for pretreated sugarcane bagasse (PSB) deconstruction and wheat arabinoxylan (WA) hydrolysis on target biotechnological applications. In this study, five hemicellulolytic enzymes-two endo-1,4xylanases (GH10 and GH11), two α-L-arabinofuranosidases (GH51 and GH54), and one β-xylosidase (GH43)-were submitted to combinatorial assays using the experimental design strategy, in order to analyze synergistic and antagonistic effects of enzyme interactions on biomass degradation. The xylooligosaccharides (XOSs) released from hydrolysis were analyzed by capillary electrophoresis and quantified by highperformance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Based on this analysis, it was possible to define which enzymatic combinations favor xylose (X1) or XOS production and thus enable the development of target biotechnological applications. Our results demonstrate that if the objective is X1 production from WA, the best enzymatic combination is GH11 +GH54+ GH43, and for xylobiose (X2) production from WA, it is best to combine GH11+GH51. However, if the goal is to produce XOS, the five enzymes used in WA hydrolysis are important, but for PSB hydrolysis, only GH11 is sufficient. If the final objective is bioethanol production, GH11 is responsible for hydrolyzing 64.3 % of hemicellulose from PSB. This work provides a basis for further studies on enzymatic mechanisms for XOS production, and the development of more efficient and less expensive enzymatic mixtures, targeting commercially viable lignocellulosic ethanol production and other biorefinery products.