Xylose Production Research Articles

Production of sugars from mixed hardwoods for use in the synthesis of sugar fatty acid esters catalyzed by immobilized‐stabilized derivatives of Candida antarctica lipase B

AbstractThe synthesis of sugar fatty acid esters (SFAEs) from lignocellulosic biomass and oleic acid (C18:1) was catalyzed by immobilized‐stabilized derivatives of Candida antarctica lipase B in a methyl ethyl ketone medium. After steam‐explosion pretreatment of mixed hardwoods and enzymatic hydrolysis at 15%wt solids, xylose and glucose were purified/concentrated to a mass ratio of ~3 to 1. These lignocellulosic sugars were superior to commercial sugars as the carbohydrate source for the esterification reaction in terms of sugar conversions. The highest conversions were obtained using 1.5% w/v of Novozyme 435 (N435, uncoated) as the biocatalyst for the synthesis of SFAEs. Coating the N435 with polyethyleneimine (PEI) prevented enzyme leakage into the reaction medium and produced 35% and 50% higher xylose and glucose conversions to SFAEs, respectively, at the same enzyme loading. After six 24 h reuse cycles with the PEI‐coated N435, xylose conversion decreased by 44%, while a 65% reduction in xylose conversion was observed with the uncoated lipase. Mass spectrometry analysis confirmed the production of xylose and glucose mono‐ and di‐esters. Our purified product presented an emulsion capacity (EC) close to that of a commercial sugar ester and the ECs of the xylose oleate, laurate, and palmitate synthesized in previous studies. © 2023 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd.

Techno-economic and life cycle assessments for bioenergy recovery from acid-hydrolyzed residues of sugarcane bagasse in the biobased xylose production platform

Techno-economic and life cycle assessments for bioenergy recovery from acid-hydrolyzed residues of sugarcane bagasse in the biobased xylose production platform

Pretreatment of moso bamboo with p-toluenesulfonic acid for the recovery and depolymerization of hemicellulose

Bamboo and its mechanical processing residues have broad prospects for high value-added utilization. In this research, p-toluenesulfonic acid was used for the pretreatment of bamboo to investigate the effects of extraction and depolymerization of hemicellulose. The response and behavior of changes of cell-wall chemical components were investigated after different solvent concentration, time, and temperature pretreatment. Results indicated that the maximum extraction yield of hemicellulose was 95.16 % with 5 % p-toluenesulfonic acid at 140 °C for 30 min. The depolymerized components of hemicellulose in the filtrate were mainly xylose and xylooligosaccharide, with xylobiose accounting for 30.77 %. The extraction of xylose from the filtrate reached a maximum of 90.16 % with 5 % p-toluenesulfonic acid at 150 °C for 30 min pretreatment. This research provided a potential strategy for the industrial production of xylose and xylooligosaccharide from bamboo and for the future conversion and utilization.

Proteomic and Transcriptomic Responses of the Desiccation-Tolerant Moss Racomitrium canescens in the Rapid Rehydration Processes.

The moss Racomitrium canescens (R. canescens) has strong desiccation tolerance. It can remain desiccated for years and yet recover within minutes of rehydration. Understanding the responses and mechanisms underlying this rapid rehydration capacity in bryophytes could identify candidate genes that improve crop drought tolerance. We explored these responses using physiology, proteomics, and transcriptomics. Label-free quantitative proteomics comparing desiccated plants and samples rehydrated for 1 min or 6 h suggesting that damage to chromatin and the cytoskeleton had occurred during desiccation, and pointing to the large-scale degradation of proteins, the production of mannose and xylose, and the degradation of trehalose immediately after rehydration. The assembly and quantification of transcriptomes from R. canescens across different stages of rehydration established that desiccation was physiologically stressful for the plants; however, the plants recovered rapidly once rehydrated. According to the transcriptomics data, vacuoles appear to play a crucial role in the early stages of R. canescens recovery. Mitochondria and cell reproduction might recover before photosynthesis; most biological functions potentially restarted after ~6 h. Furthermore, we identified novel genes and proteins related to desiccation tolerance in bryophytes. Overall, this study provides new strategies for analyzing desiccation-tolerant bryophytes and identifying candidate genes for improving plant drought tolerance.

Fruit and Restaurant Waste Polysaccharides Recycling Producing Xylooligosaccharides

A significant part of fruit production is wasted annually, a material of high value without use, causing environmental and social damage. These residues from agro-industrial processes, or those that can no longer be used in the market, can be recycled and generate value-added products by pretreatments/hydrolysis. One of the important pretreatments is acid hydrolysis, which can produce xylooligosaccharides (XOS) from biomass, a product of great commercial value in the food and pharmaceutical markets, mainly due to its prebiotic potential. Bananas, oranges, and guava generate a large volume of waste and represent much of Brazil’s fruit production. The dilute acid hydrolysis resulted in XOS production of 37.69% for banana peel, 59.60% for guava bagasse, 28.70% for orange bagasse, and 49.64% for restaurant residue. XOS were quantified by a liquid chromatograph system with a Bio-Rad Aminex HPX-87C column. The results show that, for this type of material and hydrolysis, the ideal conditions to produce XOS are high temperature, low time, and high acid concentration for banana peel residue (160 °C, 15 min, and 3% H2SO4), low temperature, low time, and high acid concentration for guava bagasse (100 °C,15 min and 3% H2SO4), high temperature and acid concentration with low time for orange bagasse (160 °C,15 min and 3% H2SO4) and high temperature and time and high acid concentration for restaurant waste (160 °C, 55 min and 3% H2SO4). This study identified acid hydrolysis conditions that maximized XOS production with a low amount of xylose production using agro-industrial and food residues, also showing the high potential of the chosen residues through the high yields of XOS production.

Effect of preferential delignification on xylooligosaccharides production from poplar by acetic acid/sodium acetate hydrolysis

Acid/base conjugate of acetic acid/sodium acetate solution (AC/SA) can efficiently produce xylooligosaccharides (XOS) with relatively high purity from poplar. The lignin in poplar is an important factor limiting the hydrolysis of xylan using enzymes and dilute acids. Until now, the effect of lignin content of poplar on XOS production by AC/SA hydrolysis is not clear. This work examined the relationship between lignin removal and XOS production from poplar by AC/SA hydrolysis. It was revealed that lignin removal of poplar enhanced XOS yield almost linearly (R2 = 0.95) in AC/SA hydrolysis. Under the optimal conditions (0.15 M AC/SA at a molar ratio of 3.0, 170 °C, 60 min), the highest XOS yield of 55.7% with a low xylose yield of 4.1% was obtained from poplar at a preferential lignin removal of 84.0%. Compared to the optimal XOS production from raw poplar, the XOS yield was increased by 32.3% and xylose production was decreased by 41.4%. Cellulase hydrolysis of the poplar residue produced a satisfying glucose yield of 92.8% and a xylose yield of 88.4%. This work proved that preferential delignification of poplar was vital in XOS and monosaccharides production by AC/SA hydrolysis combined with enzymatic hydrolysis.

Evaluation of Preparation and Detoxification of Hemicellulose Hydrolysate for Improved Xylitol Production from Quinoa Straw.

Quinoa straw is rich in hemicellulose, and it could be hydrolyzed into xylose. It is a promising energy resource alternative that acts as a potential low-cost material for producing xylitol. In this study, quinoa straw was used as a substrate subjected to the hydrolysis of dilute sulfuric acid solution. Based on the production of xylose and inhibitors during hydrolysis, the optimal conditions for the hydrolysis of hemicellulose in quinoa straw were determined. Detoxification was performed via activated carbon adsorption. The optimal detoxification conditions were determined on the basis of major inhibitor concentrations in the hydrolysate. When the addition of activated carbon was 3% at 30 °C for 40 min, the removal of formic acid, acetic acid, furfural, and 5-HMF could reach 66.52%, 64.54%, 88.31%, and 89.44%, respectively. In addition to activated carbon adsorption, vacuum evaporation was further conducted to perform two-step detoxification. Subsequently, the detoxified hydrolysate was used for xylitol fermentation. The yield of xylitol reached 0.50 g/g after 96 h of fermentation by Candida tropicalis (CICC 1779). It is 1.2-fold higher than that obtained through the sole vacuum evaporation method. This study validated the feasibility of xylitol production from quinoa straw via a biorefinery process.

Production of xylose through enzymatic hydrolysis of glucuronoarabinoxylan from brewers’ spent grain

Xylose is an abundant bioresource for obtaining diverse chemicals and added-value products. The production of xylose from green alternatives like enzymatic hydrolysis is an important step in a biorefinery context. This research evaluated the synergism among four classes of hydrolytic purified enzymes—endo-1,4-β-xylanase, α-l-arabinofuranosidase, β-xylosidase, and α-d-glucuronidase—over hydrolysis of glucuronoarabinoxylan (GAX) obtained from brewers’ spent grain (BSG) after alkaline extraction and ethanol precipitation. First, monosaccharides, uronic acids and glycosidic-linkages of alkaline extracted GAX fraction from BSG were characterized, after that different strategies based on the addition of one or two families of enzymes—endo-1,4-β-xylanase (GH10 and GH11) and α-l-arabinofuranosidase (GH43 and GH51)—cooperating with one β-xylosidase (GH43) and one α-d-glucuronidase (GH67) into enzymatic hydrolysis were assessed to obtain the best yield of xylose. The xylose release was monitored over time in the first 90 min and after a prolonged reaction up to 48 h of reaction. The highest yield of xylose was 63.6% (48 h, 40 ℃, pH 5.5), using a mixture of all enzymes devoid of α-l-arabinofuranosidase (GH43) family. These results highlight the importance of GH51 arabinofuranosidase debranching enzyme to allow a higher cleavage of the xylan backbone of GAX from BSG and their synergy with 2 endo-1,4-β-xylanase (GH10 and GH11), one β-xylosidase (GH43) and the inclusion of one α-d-glucuronidase (GH67) in the reaction system. Therefore, this study provides an environmentally friendly process to produce xylose from BSG through utilization of enzymes as catalysts.Graphical

Impact of pre-extraction on xylose recovery from two lignocellulosic agro-wastes

A dilute acid hydrolysis of rice husk (RH), wheat straw (WS), and their extractive-free residues was investigated with the objective of recovering the highest yield of xylose while keeping at minimum its conversion into furfural. The hydrolysis conditions were determined for different concentrations of sulfuric acid and different reaction times at 121 °C. The pre-extraction with ethanol-water (1:1, v/v) was also examined as a parameter. Using response surface methodology, the optimum conditions for xylose production were identified as 1.8% of acid and 41.4 min of hydrolysis time for RH, while those for its counterpart EF-RH (extractives-free rice husks) were 1.0% acid concentration, for 60 min. The same conditions were also predicted for WS and its EF-WS. Under these conditions, the xylose yield was 79.6%, 82.8%, 94.3%, and 88.6% for RH, EF-RH, WS, and EF-RW, respectively. Under these conditions the minimal furfural yields obtained were 1.2% and 1.3% for RH and EF-RH, and 0.8% and 1.5%, for WS and EF-WS, respectively. These results suggested that the pre-extraction step before the acid hydrolysis affected, at least in part, the xylose recovery from RH, but it was not necessary for a better xylose yield of WS for its bioconversion into valuable bioproducts like xylitol.

High-level production of xylose from agricultural wastes using GH11 endo-xylanase and GH43 β-xylosidase from Bacillus sp.

As a promising feedstock, alkali-extracted xylan from lignocellulosic biomass is desired for producing xylose, which can be used for renewable biofuels production. In this study, an efficient pathway has been established for low-cost and high-yield production of xylose by hydrolysis of alkali-extracted xylan from agricultural wastes using an endo-1,4-xylanase (XYLA) from Bacillus safensis TCCC 111022 and a β-xylosidase (XYLO) from B. pumilus TCCC 11573. The optimum activities of recombinant XYLA (rXYLA) and XYLO (rXYLO) were 60℃ and pH 8.0, and 30℃ and pH 7.0, respectively. They were stable over a broad pH range (pH 6.0-11.0 and 7.0-10.0). rXYLO showed a relatively high xylose tolerance up to 100mM. Furthermore, the yield of xylose from wheat straw, rice straw, corn stover, corncob and sugarcane bagasse by rXYLA and rXYLO was 63.77%, 71.76%, 68.55%, 53.81%, and 58.58%, respectively. This study demonstrated a strategy to produce xylose from agricultural wastes by integrating alkali-extracted xylan and enzymatic hydrolysis.

Enhanced catalytic performance of thermophilic GH11 xylanase by fusing carbohydrate-binding module 9-2 and linker for better synergistic degradation of wheat bran

In this study, the catalytic activity of xynAm1 (a thermophilic xylanase family 11 variant) was significantly enhanced by fusing a carbohydrate-binding module (CBM) 9–2. First, CBM9–2 was fused to the N- and C-termini of xynAm1, generating the fusion enzymes C-X and X-C, respectively. The specific activity of C-X was 19.0 U/μM, which was 2.3-fold and 1.1-fold higher than that of xynAm1 and X-C, respectively. Then, the flexible linker (GGGGS)2 was used to fuse CBM9–2 at the N-terminus of xynAm1, yielding C-F2-X with an additional 15.91-fold increase in the specific activity. By analyzing their modeled structures, the hydrogen bonds between xynAm1 and CBM in C-F2-X made the distance between the catalytic active site E379 and binding site W176 shorter by 8 Å than that in C-X. Meanwhile, the sugarcane xylan hydrolysis with C-F2-X produced 5.42 times higher amount of the xylose than that with xynAm1. When C-F2-X (200 U) and cellulase (200 U) were added to 30 mL suspension of wheat bran (1.5 g), the reducing sugar content and dry weight loss rate reached 143.23 nM and 82.7% after 24 h reaction, respectively. Therefore, the fusion enzyme C-F2-X could be a robust candidate enzyme for xylose production and lignocellulose degradation.

Effects of Reactive Condition and Mechanochemical Treatment on Xylose Production from Rice Husk by Dilute Acid Hydrolysis

Effects of Reactive Condition and Mechanochemical Treatment on Xylose Production from Rice Husk by Dilute Acid Hydrolysis

Production of tailored xylo-oligosaccharides from beechwood xylan by different enzyme membrane reactors and evaluation of their prebiotic activity

Xylo-oligosaccharides (XOs) from xylans are gaining interest due to their wide use in food, feed and pharmaceutical industry. In this work, the enzymatic production of XOs from beechwood xylan in batch, continuous and semi-continuous enzyme membrane reactor mode was compared. The potential of an inline viscometer for real-time monitoring of the hydrolysis was assessed as well. In all modes, an initial concentration of 7% (w/w) beechwood xylan was applied at a temperature of 50 °C and a pH of 5.8. Initially, the effect of enzyme dosage was investigated in batch mode (0.5, 2.6, 12, 26 and 720 U of Cellic®CTec2.g−1 xylan). Higher enzyme dosages led to a faster hydrolysis rate, but also to an undesirable higher production of xylose. The introduction of enzyme membrane reactors allowed production of XOs with weight average molecular weights of ca. 5–8.9 kDa combined with negligible xylose quantities (<3% in freeze dried product). The semi-continuous configuration has the edge in comparison to the full continuous configuration in terms of enzyme consumption and ease of operation. In vitro fermentations with three different gut bacteria were performed and confirmed the prebiotic properties of the produced XOs with average degree of polymerization of 48.

Insights into the mechanism for the high-alkaline activity of a novel GH43 β-xylosidase from Bacillus clausii with a promising application to produce xylose

Nowadays, alkali-tolerant β-xylosidases and their molecular mechanism of pH adaptability have been poorly studied. Here, a novel GH43 β-xylosidase (XYLO) was isolated from Bacillus clausii TCCC 11004, and the recombinant β-xylosidase (rXYLO) was most active at pH 8.0 and stable in a broad pH range (7.0–11.0), exhibiting superior alkali tolerance. Molecular dynamics simulation indicated that XYLO showed a notable overall structural stability and an enlargement of substrate binding pocket under alkaline condition, resulting in the formation of a new hydrogen bond between substrate and Arg286 of XYLO, and the tight binding played a key role in improving the XYLO activity with the increasing pH. Moreover, rXYLO with an endo-xylanase resulted in high xylose yields by hydrolyzing alkali-extracted xylan from agricultural wastes. This work would provide an alkali-tolerant β-xylosidase, enhance the understanding for the relationship of structure and activity adapted to the high-alkaline environment, and promote its application in xylose production.

Efficacious bioconversion of waste walnut shells to xylotetrose and xylopentose by free xylanase (Xy) and MOF immobilized xylanase (Xy-Cu-BTC)

This study uses a cost effective and efficient method for production of higher DP (degree of polymerization) Xylooligosaccharides (XOS) from xylan extracted from the waste walnut shells. Copper based metal organic framework (Cu-BTC MOF) was prepared for immobilization of free xylanase (Xy) enzyme by green synthesis method. Both free and immobilized xylanase (Xy-Cu-BTC) were able to cause the bioconversion of xylan (87.4% yield) into XOS. Predominant production of xylotetrose (X4) and xylopentose (X5) was observed for both the methods. Percentage XOS conversion for free enzyme (Xy) was found to be 4.1% X4 and 60.57% X5 whereas these values increased in case of immobilized system where 11.8% X4 and 64.2% X5 were produced. Xylose production was minute in case of immobilized xylanase 0.88% which makes it a better method for XOS production free from xylose interference. Xy-Cu-BTC MOF can hence be used as an attractive alternative for pure XOS production.

A two-stage heating process with low energy consumption for treatment of preliminary desalinated impregnation effluent to produce xylose

Production of xylose from preliminary desalinated impregnation effluent (PDSIE) containing hemicellulose is an economical way of the effluent treatment. However, due to the high alkali and salt contents in PDSIE, its resource utilization is limited in the developed treatment process for pulp-impregnated effluent that has been deeply desalted. In this study, based on analysis of reaction rate and kinetic characteristics of pre-hydrolysis, a two-stage pre-hydrolysis heating process including heating at a high temperature for a short time followed by slow cooling to enzymatic hydrolysis temperature (HCP) with low energy consumption was developed for PDSIE. The heating time was shortened from 2 h to 0.5 h, the inhibition of conversion from hemicellulose to xylose by the high alkali and salt contents in PDSIE was alleviated, and the loss of xylose was reduced by HCP, compared to those under the constant temperature heating conditions. The heating cost based on coal consumption was reduced by 75.54% in HCP according to the preliminary economic analysis. Based on xylose yield and energy-saving results, the temperature in the first stage of HCP was determined to be 120 °C, and the cooling time in the second stage was determined to be 6 h.

Effects of ultrasonic-assisted alkaline pretreatment on xylose production from pineapple peel waste

The pineapple industry generates large amounts of unusable waste (peel and core) with adverse environmental impacts. This experimental study aims to systemize the potential of ultrasonic-assisted alkaline pretreatment for xylose production from pineapple peel waste. The best condition for single alkaline pretreatment (1 % NaOH w/v, 100 °C, 60 min) has obtained hemicellulose, cellulose, and lignin composition at 34.80 %, 32.16 %, and 8.66 %, respectively, retained in the biomass. Meanwhile, a combination of alkaline (1 % NaOH, w/v) and ultrasonic (frequency 40 kHz, 45 min) pretreatment has obtained the percentage yield of hemicellulose and lignin at 51.15 % and 7.15 %, respectively. Both single alkaline and ultrasonic-assisted alkaline pretreated samples were subsequently hydrolyzed with 2 % H2SO4 (w/v). After acid hydrolysis for 30 min, the maximum xylose concentration of 48.85 g.L-1 was achieved by using ultrasonic-assisted alkaline pretreatment, while single alkaline pretreatment contributed to the lowest yield of xylose (37.11 g.L-1). It is shown that the ultrasonic-assisted alkaline treatment is more favorable than single alkaline pretreatment as it can produce high xylose concentration after the subsequent hydrolysis. These results indicated that ultrasonic-assisted alkaline pretreatment and its subsequent acid hydrolysis were appropriate for producing xylose from pineapple peel waste.

Kinetic model analysis of mild autohydrolysis of eucalyptus woodchips for xylose production

The autohydrolysis process of eucalyptus hemicelluloses was studied. The effect of hydrolysis temperature and soaking time on the dissolution of hemicellulose from eucalyptus chips was considered, and the process conditions were further optimized by P factor. The kinetic equations for the hemicellulose reaction were derived by studying the reaction process of hemicellulose during the pre-hydrolysis of eucalyptus chips, based on the reaction activation energy of xylose from eucalyptus chips and the investigated reaction mechanism of eucalyptus pre-hydrolysis process. The results demonstrated the feasibility of efficient extraction and utilization of hemicellulose in the process of dissolving pulp preparation from eucalyptus chips.

Enzymatic Glucose and Xylose Production from Paper Mill Rejects

Recycled paper fiber rejects have shown potential as a source of waste-to-resource carbohydrates for renewable chemicals production. This study examined three classes of recycled paper fines (old corrugated containers, old newspaper, and mixed office waste) and two industrial papermaking rejects streams from different recycling mills (one mill processes linerboard and the other old corrugated cardboard). The effect of chemical pretreatment using dilute sodium hydroxide, hot water and dilute sulfuric acid on enzymatic glucose and xylose yields was evaluated. Enzymatic hydrolysis results indicated that recycled fiber streams with more old corrugated cardboard have higher potential to produce carbohydrates. The recycled cardboard rejects produced more glucose and xylose per kilogram of rejects than the linerboard rejects under all untreated and pretreated conditions. The highest producing rejects sample was sodium hydroxide pretreated cardboard rejects with 373 g glucose and 61 g xylose produced per kilogram of rejects. However, a simple hot water pretreatment showed similar results, with 335 g glucose and 58 g xylose produced per kilogram of rejects. The hot water pretreatment is recommended due to its comparable yield and lower chemical addition.

Fibrolytic rumen bacteria of camel and sheep and their applications in the bioconversion of barley straw to soluble sugars for biofuel production.

Lignocellulosic biomass such as barley straw is a renewable and sustainable alternative to traditional feeds and could be used as bioenergy sources; however, low hydrolysis rate reduces the fermentation efficiency. Understanding the degradation and colonization of barley straw by rumen bacteria is the key step to improve the utilization of barley straw in animal feeding or biofuel production. This study evaluated the hydrolysis of barley straw as a result of the inoculation by rumen fluid of camel and sheep. Ground barley straw was incubated anaerobically with rumen inocula from three fistulated camels (FC) and three fistulated sheep (FR) for a period of 72 h. The source of rumen inoculum did not affect the disappearance of dry matter (DMD), neutral detergent fiber (NDFD). Group FR showed higher production of glucose, xylose, and gas; while higher ethanol production was associated with cellulosic hydrolysates obtained from FC group. The diversity and structure of bacterial communities attached to barley straw was investigated by Illumina Mi-Seq sequencing of V4-V5 region of 16S rRNA genes. The bacterial community was dominated by phylum Firmicutes and Bacteroidetes. The dominant genera were RC9_gut_group, Ruminococcus, Saccharofermentans, Butyrivibrio, Succiniclasticum, Selenomonas, and Streptococcus, indicating the important role of these genera in lignocellulose fermentation in the rumen. Group FR showed higher RC9_gut_group and group FC revealed higher Ruminococcus, Saccharofermentans, and Butyrivibrio. Higher enzymes activities (cellulase and xylanase) were associated with group FC. Thus, bacterial communities in camel and sheep have a great potential to improve the utilization lignocellulosic material in animal feeding and the production of biofuel and enzymes.