High Content Of Xylose Research Articles

The effect of extraction solution pH level on the physicochemical properties and α-glucosidase inhibitory potential of Fucus vesiculosus polysaccharide

In this study, five Fucus vesiculosus polysaccharides (FVPs; FVP-2, FVP-4, FVP-7, FVP-10, and FVP-13) were extracted by different pH, and their physicochemical characteristics and α-glucosidase inhibitory activity were investigated. Results showed that extraction pH significantly affected the chemical composition, molecular weight, zeta potential, structure characterization, and rheological property of FVPs. The viscosity consistency index of Fucus vesiculosus polysaccharides at high concentration (40 mg/mL) were ranked in decreasing order as FVP-10 > FVP-4 > FVP-7 > FVP-2 > FVP-13, which was strictly in accordance with the order of Mw. Among the five polysaccharides, FVP-13 showed the strongest α-glucosidase inhibitory activity, which might be related to its the lowest Mw and relatively higher xylose content. Fluorescence quenching analysis indicated that the interaction of FVPs and α-glucosidase was predominated by a dynamic mechanism. Thermodynamic analysis showed that the main driving forces for the interaction was hydrophobic interaction. Circular dichroism spectrum analysis found that FVPs could induce the secondary structure of α-glucosidase changes like the decrease of β-sheet content and the increase of β-turn and random coil content to inhibit α-glucosidase activity. These results suggested that extraction with high pH was an efficient method to obtain FVPs with strong α-glucosidase inhibition activity.

Structure of corn bran hemicelluloses isolated with aqueous ethanol solutions and their potential to produce furfural

The alkali-soluble hemicelluloses extracted with 10% KOH solution from corn bran were further isolated with different concentrations of aqueous ethanol solutions. Herein 92.2% of the original hemicelluloses can be obtained and the cellulase enzymatic hydrolysis rate of the alkali treated corn bran can reach to 97.2%. The corn bran hemicelluloses were mainly glucuronoarabinoxylan, in which xylose (48.4–53.8%) and arabinose (27.8–33.2%) were the main components. More linear hemicelluloses with high molecular weight tended to be precipitated in low concentration aqueous ethanol solutions. Furthermore, the relationship between the structural features of these alkali-soluble corn bran hemicelluloses and their furfural yield was investigated in MIBK (methyl isobutyl ketone)/H2O biphasic system. Results showed that the hemicelluloses with high xylose content are benefit to the furfural production, and the highest furfural yield of 67.7% was obtained.

Xylitol Production by Candida Species from Hydrolysates of Agricultural Residues and Grasses

Xylitol is an industrially important chemical due to its commercial applications. The use of xylitol as a sweetener as well as its utilization in biomedical applications has made it a high value specialty chemical. Although several species of yeast synthesize xylitol, this review focusses on the species of the genus Candida. The importance of the enzyme xylitol reductase present in Candida species as it relates to their ability to synthesize xylitol was examined. Another focus of this work was to review prior studies examining the ability of the Candida species to synthesize xylitol effectively from hydrolysates of agricultural residues and grasses. An advantage of utilizing such a hydrolysate as a substrate for yeast xylitol production would be decreasing the overall cost of synthesizing xylitol. The intent of this review was to learn if such hydrolysates could substitute for xylose as a substrate for the yeast when producing xylitol. In addition, a comparison of xylitol production by Candida species should indicate which hydrolysate of agricultural residues and grasses would be the best substrate for xylitol production. From studies analyzing previous hydrolysates of agricultural residues and grasses, it was concluded that a hydrolysate of sugarcane bagasse supported the highest level of xylitol by Candida species, although corncob hydrolysates also supported significant yeast xylitol production. It was also concluded that fewer studies examined yeast xylitol production on hydrolysates of grasses and that further research on grasses may provide hydrolysates with a higher xylose content, which could support greater yeast xylitol production.

Particle size influence on the composition of sugars in corncob hemicellulose hydrolysate for xylose fermentation by Meyerozyma caribbica

The xylitol production was performed with acidophilic Meyerozyma caribbica. The particle size of 0.02 ± 0.01 to 0.1 ± 0.05 mm was rich in glucose (12.0 ± 0.5 g/L), whereas 0.5 ± 0.25 to 2.0 ± 0.5 mm had a high content of xylose (8.0 ± 0.5 g/L). The xylitol production in the synthetic, non-detoxified and detoxified hydrolysate media was studied (50 ± 0.5 g/L) using 10% v/v non - induced cells of M. caribbica for 120 h. At the end of fermentation with the specific growth rate of 0.056 ± 0.01 (μ), xylitol yields of 45.00 ± 1.00%, 10.00 ± 1.00% and 54.00 ± 1.00% were obtained. The detoxification of the hydrolysate prepared using an identified corncob particle size of 0.5 ± 0.25 to 2.0 ± 0.5 mm could be used as the prospective pretreatment process for ecofriendly and industrial scale production of xylitol with M. caribbica.

The effect of Moringa peregrina seed husk on the in vitro starch digestibility, microstructure, and quality of white wheat bread

This study aimed to investigate the chemical composition and monosaccharide contents of Moringa peregrina seed husk powder (MSH), as well as its effect on the nutritional characteristics, structural properties, quality performance, in vitro starch digestibility, and retrogradation properties of white wheat bread. The results showed that MSH is a rich source of dietary fiber (55.45%), with its predominant monosaccharides being xylose (46.92%), glucose (33.76%), and arabinose (9.93%). The high content of xylose in MSH confirms it can be utilized as a raw material for the production of different chemical compounds (e.g., xylitol). The addition of MSH increased the protein content and dietary fiber of the wheat bread; whereas, it decreased fat and carbohydrate contents besides the caloric value. Scanning electron micrographs indicated an incomplete gelatinization in the case of the bread containing MSH, indicating the reinforcement of starch digestion in this bread. The results from X-ray diffraction, Mixolab, and texture analyses indicated that MSH decreased the rate of starch retrogradation. Therefore, based on the findings of this experiment, MSH can be used in wheat bread formulations as a rich source of fiber for the potential glycemic control and retarding starch retrogradation.

Unmasking the heterogeneity of carbohydrates in heartwood, sapwood, and bark of Eucalyptus

In this study, the cellulose and hemicelluloses in heartwood, sapwood, and bark of E. urophylla × E. grandis were comprehensively investigated. The ultrastructural topochemistry of carbohydrates in cell walls was examined in situ by confocal Raman microscopy. Cellulose and alkali-extractable hemicelluloses samples were isolated from different tissues and comparatively characterized by compositional carbohydrate analyses, determination of molecular weights, FT-IR spectroscopy, and XRD and NMR techniques. It was found that among all of the samples, heartwood cellulose had the highest molecular weight as well as the lowest degree of crystallinity. Meanwhile the hemicelluloses in heartwood had higher xylose content, lower degree of branching, slightly lower molecular weights but narrower polydispersity than those in sapwood. The eucalyptus hemicelluloses mainly consisted of (1→4)-β-D-xylan backbone with glucuronic acid side chains. Furthermore, the hemicelluloses isolated from sapwood had a higher degree of substitution with terminal galactose than those isolated from heartwood and bark.

Xyloglucan intake attenuates myocardial injury by inhibiting apoptosis and improving energy metabolism in a rat model of myocardial infarction

The development of coronary heart disease can be divided into preocclusion and postocclusion steps. We previously showed that cell wall polysaccharides consisting of a high content of arabinose and/or xylose, such as apple pectin, protected against myocardial injury by inhibiting postocclusion steps. We hypothesized that xyloglucan, another apple cell wall polysaccharide that consists of a high content of xylose, might also show myocardial protection. To test the hypothesis, rats were supplemented with either tamarind xyloglucan (TXG) (1, 10, and 100 mg/kg per day) or cotton cellulose (CCL) (100mg/kg per day) for 3 days. Then, rats underwent 30 minutes of ischemia followed by 3 hours of reperfusion. Supplementation with TXG at a dosage greater than 10mg/kg per day significantly reduced the infarct size (IS), whereas supplementation with CCL at 100mg/kg per day did not reduce IS. TXG supplementation up-regulated the expression of myoglobin and fatty acid-binding protein, both of which are known to be involved in apoptosis and ATP generation. Indeed, TXG supplementation inhibited apoptosis through decrease in p38 and JNK phosphorylation, increase in Bcl-2/Bax ratio, inhibition in the conversion of procaspase-3 to cleaved caspase-3, and decrease in the generation of DNA nicks. From these results, we demonstrated that xyloglucan in apple can protect against myocardial injury by inhibiting apoptosis and improving energy metabolism. Therefore, apple xyloglucan and pectin contribute to the known beneficial effects of apple in reducing the risk of coronary heart disease by blocking postocclusion steps through apoptosis inhibition. In addition, this study demonstrates the feasibility of developing TXG as a cardioprotectant.

Effect of structural characteristics of corncob hemicelluloses fractionated by graded ethanol precipitation on furfural production

In the present study, a graded ethanol precipitation technique was employed to obtain hemicelluloses from the alkali-extracted corncob liquid. The relationship between the structural characteristics of alkali-soluble corncob hemicelluloses and the production of furfural was investigated by a heterogeneous process in a biphasic system. Results showed that alkali-soluble corncob hemicelluloses mainly consisted of glucuronoarabinoxylans and l-arabino-(4-O-methylglucurono)-d-xylans, and the drying way had less influence on the sugar composition, molecular weights and the functional groups of hemicelluloses obtained by the different ethanol concentration precipitation except for the thermal property, the amorphous structure and the ability for the furfural production. Furthermore, alkali-soluble corncob hemicelluloses with higher xylose content, lower branch degree, higher polydispersity and crystallinity contributed to the furfural production. A highest furfural yield of 45.41% with the xylose conversion efficiency of 99.06% and the furfural selectivity of 45.84% was obtained from the oven-dried hemicelluloses precipitated at the 30% (v/v) ethanol concentration.

Effect of Carbon Source on Properties and Antioxidant Potential of Exopolysaccharides Produced by Trametes robiniophila (Higher Basidiomycetes).

The effects of carbon source on properties and antioxidant potential of exopolysaccharides (EPS) produced by Trametes robiniophila were investigated in this study. The results indicated that the EPS production varied with five different carbon sources. The predominant carbohydrate compositions in EPSs identified were glucose and mannose. Then, FT-IR spectral analysis revealed prominent characteristic groups in the EPSs. Furthermore, thermogravimetric analysis (TGA) indicated the EPS with lactose as the carbon source showed different degradation behavior as compared to the other four EPSs, probably due to larger ribose content as one of major monosaccharides in the EPS. The variation also affects the antioxidant activities investigated by using hydroxyl and DPPH radical scavenging assay. Sucrose was the best carbon source from the viewpoint of antioxidant activity due to the relatively high xylose content in the EPS.

Detoxification of hemicellulosic hydrolysates from extracted olive pomace by diananofiltration

Xylitol can be obtained from the pentose-rich hemicellulosic fraction of agricultural residues, such as extracted olive pomace, by fermentation. Dilute acid hydrolysis of lignocellulosic materials, produces the release of potential inhibitory compounds mainly furan derivatives, aliphatic acids, and phenolic compounds. In order to study the potential on the increase of the hydrolysate fermentability, detoxification experiments based on diananofiltration membrane separation processes were made. Two membranes, NF270 and NF90, were firstly evaluated using hydrolysate model solutions under total recirculation mode, to identify the best membrane for the detoxification. NF270 was chosen to be used in the diananofiltration experiment as it showed the lowest rejection for toxic compounds and highest permeate flux. Diananofiltration experiments, for hydrolysate model solutions and hydrolysate liquor, showed that nanofiltration is able to deplete inhibitory compounds and to obtain solutions with higher xylose content. Conversely to non-detoxified hydrolysates, nanofiltration detoxified hydrolysates enabled yeast growth and xylitol production by the yeast Debaryomyces hansenii, clearly pointing out that detoxification is an absolute requirement for extracted olive pomace dilute acid hydrolysate bioconversion.

Anthrahydroquinone-2,6,-disulfonate (AH2QDS) increases hydrogen molar yield and xylose utilization in growing cultures of Clostridium beijerinckii

H(2) production and xylose utilization were investigated using the fermentative culture Clostridium beijerinckii NCIMB 8052. Adding anthrahydroquinone-2,6-disulfonate (AH(2)QDS) increased the extent of xylose utilization by 56% and hydrogen molar yield by 24-37%. Enhanced hydrogen molar yield correlated with increased xylose utilization and increases in the acetate/butyrate product ratio. An electron balance indicated that AH(2)QDS shifted the electrons from the butyric acid pathway (NADH-dependent pathway) to the acetic acid pathway (non-NADH-dependent pathway), putatively creating a surplus of reducing equivalents that were then available for hydrogen production. These data demonstrate that hydrogen yield and xylose utilization can be manipulated by amending redox active molecules into growing cultures. This will impact biohydrogen/biofuel production by allowing physiological manipulations of growing cells for increased (or decreased) output of selected metabolites using amendments that are not consumed during the reactions. Although the current yield increases are small, they suggest a target for cellular alterations. In addition, increased xylose utilization will be critical to the fermentation of pretreated lignocellulosic feedstocks, which may have higher xylose content.

Optimization of steam pretreatment conditions for enzymatic hydrolysis of poplar wood

Abstract Steam refining was investigated as a pretreatment for enzymatic hydrolysis of poplar wood from a short rotation plantation. The experiments were carried out without debarking to use an economically realistic raw material. Steam refining conditions were varied in the range of 3–30 min and 170–220°C, according to a factorial design created with the software JMP from SAS Institute Inc., Cary, NC, USA. Predicted steaming conditions for highest glucose and xylose yields after enzymatic hydrolysis were at 210°C and 15 min. Control tests under the optimized conditions verified the predicted results. Further pretreatments without bark showed that the enzymes were not significantly inhibited by the bark. The yield of glucose and xylose was 61.9% of theoretical for the experiments with the whole raw material, whereas the yield for the experiments without bark was 63.6%. Alkaline extraction of lignin from the fibers before enzymatic hydrolysis resulted in an increase of glucose yields from mild pretreated fibers and a decrease for severe pretreated fibers. The extracted lignin had a high content of xylose of up to 14% after very mild pretreatments. On the other hand, molecular weights of the extracted lignin increased substantially after pretreatments with a severity factor above 4. Hence, alkaline extraction of the lignin seems only attractive in a narrow range of steaming conditions.

Efficient production of l-lactic acid from corncob molasses, a waste by-product in xylitol production, by a newly isolated xylose utilizing Bacillus sp. strain

Lignocellulosic biomass-derived sugars are considered nowadays to be an economically attractive carbohydrate feedstock for large-scale fermentations of bulk chemicals such as lactic acid. In the present study, corncob molasses containing a high content of xylose, which is one of the lignocellulosic biomasses and a waste by-product from xylitol production, was used for l-lactic acid production via a newly isolated xylose utilizing Bacillus sp. strain XZL9. Bacillus sp. strain XZL9 can utilize the mixture of sugars including xylose, arabinose, and glucose in corncob molasses for l-lactic acid production. High concentration of l-lactic acid (74.7 g l −1) was obtained from corncob molasses (initial total sugars of 91.4 g l −1) in fed-batch fermentation. This study provides an encouraging means of producing l-lactic acid from lignocellulosic resource such as the low-cost corncob molasses.

Molecular xylem cell wall structure of an inclined Cycas micronesica stem, a tropical gymnosperm

The molecular structure of tracheid walls of an inclined eccentrically grown stem of Cycas micronesica K.D. Hill did not differ between the upper and lower side. The absence the typical molecular features of compression wood tracheids, i.e. an increased galactose and lignin content as well as an increased microfibril angle, indicated that cycads do not have the ability to form even very mild forms of compression wood, which lacks anatomical features commonly observed in compression wood. Analysis of the sugar monomers in Cycas micronesica tracheids did reveal a rather unique composition of the non-cellulosic polysaccharides for a gymnosperm. The low mannose and high xylose content resembled a cell wall matrix common in angiosperms. The crystalline cellulose structure in Cycas micronesica tracheids closely resembled those of secondary cell walls in Picea sitchensis (Bong.) Carr. tracheids. However, the spacing between the sheets of cellulose chains was wider and the cellulose fibrils appeared to form larger aggregates than in Sitka spruce tracheids.

Variations in chemical composition and structure of macromolecular components in different morphological regions and maturity stages of Arundo donax

Arundo donax plants were manually separated into fractions of different morphological regions (internodes, nodes and foliage) at different stages of maturity and submitted to chemical composition studies. General chemical composition was determined by established methods. The polysaccharides were fractionated by successive extractions of holocellulose with aqueous KOH solutions. The sugar composition was determined by hydrolysis of polysaccharides followed by GC analysis of neutral sugars as alditol acetates and spectrophotometric determination of uronic acids. In situ lignins, milled wood lignins (MWL) and dioxane lignin were characterised by permanganate oxidation followed by GC and GC-MS analysis of the methylated oxidation products and by quantitative 13C NMR spectroscopy. The results of general chemical analysis evidenced the different relative abundance of holocellulose, lignin, proteins, extractives and ashes in internodes, nodes and foliage, at different stages of maturity. In internodes, nodes and foliage about 70–80% of hemicelluloses (21–30% o.d. material) were easily extracted with 5% KOH aqueous solutions. The analysis of hemicelluloses indicated that they are constituted mainly by arabinoglucuronoxylans with a xylose:arabinose:uronic acid ratio of 91–93:5–7:2 for internodes. The high content of xylose in Arundo donax stem (24–27% o.d. material) and the easy extraction of hemicelluloses opens new perspectives for the use of this reed as a source of pentosans. The results obtained by the permanganate oxidation method indicated that Arundo donax lignins are essentially H-G-type with approximate H:G:S proportions of (32–36):(59–61):(5–8) in internodes. The H units are constituted mainly by esterified p-coumaric acid. These results were confirmed by quantitative 13C NMR spectroscopy of isolated dioxane lignin. The quantity of condensed structures in in situ lignin decreases from the older to the younger parts of the stems and is much higher in nodes than internodes.

Chemical-modification studies of a unique sialic acid-binding lectin from the snail Achatina fulica. Involvement of tryptophan and histidine residues in biological activity.

A unique sialic acid-binding lectin, achatininH (ATNH) was purified in single step from the haemolymph of the snail Achatina fulica by affinity chromatography on sheep submaxillary-gland mucin coupled to Sepharose 4B. The homogeneity was checked by alkaline gel electrophoresis, immunodiffusion and immunoelectrophoresis. Amino acid analysis showed that the lectin has a fairly high content of acidic amino acid residues (22% of the total). About 1.3% of the residues are half-cystine. The glycoprotein contains 21% carbohydrate. The unusually high content of xylose (6%) and fucose (2.7%) in this snail lectin is quite interesting. The protein was subjected to various chemical modifications in order to detect the amino acid residues and carbohydrate residues present in its binding sites. Modification of tyrosine and arginine residues did not affect the binding activity of ATNH; however, modification of tryptophan and histidine residues led to a complete loss of its biological activity. A marked decrease in the fluorescence emission was found as the tryptophan residues of ATNH were modified. The c.d. data showed the presence of an identical type of conformation in the native and modified agglutinin. The modification of lysine and carboxy residues partially diminished the biological activity. The activity was completely lost after a beta-elimination reaction, indicating that the sugars are O-glycosidically linked to the glycoprotein's protein moiety. This result confirms that the carbohydrate moiety also plays an important role in the agglutination property of this lectin.

Monomeric constituents of the mesogleal polysaccharides of Chrysaora quinquecirrha (scyphozoa: semaeostomeae)

1. 1. Polysaccharides were extracted from the mesoglea of Chrysaora quinquecirrha medusa and recovered by ethanol-NaCl precipitation. 2. 2. After hydrolysis in 6 N HCl, the monomeric constituents of the mesogleal polysaccharides were identified using TLC and quantified using four colorimetric reactions. 3. 3. The presence of hexoses, pentoses, uronic acids and hexosamines indicates that complex carbohydrates are undoubtedly associated with the gelatinous matrix. 4. 4. Of particular interest is the high content of xylose and the almost equal molar amount of fucose in the hydrolysate.