• Nutrition Research and Practice
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• v.10 no.1
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• pp.11-18
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• 2016

BACKGROUND/OBJECTIVES: Type 2 diabetes (T2D) is more frequently diagnosed and is characterized by hyperglycemia and insulin resistance. $\small{D}$-xylose, a sucrase inhibitor, may be useful as a functional sugar complement to inhibit increases in blood glucose levels. The objective of this study was to investigate the anti-diabetic effects of $\small{D}$-xylose both in vitro and stretpozotocin (STZ)-nicotinamide (NA)-induced models in vivo. MATERIALS/METHODS: Wistar rats were divided into the following groups: (i) normal control; (ii) diabetic control; (iii) diabetic rats supplemented with a diet where 5% of the total sucrose content in the diet was replaced with $\small{D}$-xylose; and (iv) diabetic rats supplemented with a diet where 10% of the total sucrose content in the diet was replaced with $\small{D}$-xylose. These groups were maintained for two weeks. The effects of $\small{D}$-xylose on blood glucose levels were examined using oral glucose tolerance test, insulin secretion assays, histology of liver and pancreas tissues, and analysis of phosphoenolpyruvate carboxylase (PEPCK) expression in liver tissues of a STZ-NA-induced experimental rat model. Levels of glucose uptake and insulin secretion by differentiated C2C12 muscle cells and INS-1 pancreatic ${\beta}$-cells were analyzed. RESULTS: In vivo, $\small{D}$-xylose supplementation significantly reduced fasting serum glucose levels (P < 0.05), it slightly reduced the area under the glucose curve, and increased insulin levels compared to the diabetic controls. $\small{D}$-xylose supplementation enhanced the regeneration of pancreas tissue and improved the arrangement of hepatocytes compared to the diabetic controls. Lower levels of PEPCK were detected in the liver tissues of $\small{D}$-xylose-supplemented rats (P < 0.05). In vitro, both 2-NBDG uptake by C2C12 cells and insulin secretion by INS-1 cells were increased with $\small{D}$-xylose supplementation in a dose-dependent manner compared to treatment with glucose alone. CONCLUSIONS: In this study, $\small{D}$-xylose exerted anti-diabetic effects in vivo by regulating blood glucose levels via regeneration of damaged pancreas and liver tissues and regulation of PEPCK, a key rate-limiting enzyme in the process of gluconeogenesis. In vitro, $\small{D}$-xylose induced the uptake of glucose by muscle cells and the secretion of insulin cells by ${\beta}$-cells. These mechanistic insights will facilitate the development of highly effective strategy for T2D.

• Journal of Microbiology and Biotechnology
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• v.23 no.4
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• pp.560-564
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• 2013

${\small{D}}$-Ribose is a value-added five-carbon sugar used for riboflavin production. To investigate the effects of oxygen supply and mixed sugar concentration on microbial production of ${\small{D}}$-ribose, a transketolase-deficient Bacillus subtilis SPK1 was cultured batch-wise using xylose and glucose. A change of agitation speed from 300 rpm to 600 rpm at 1 vvm of air supply increased both the xylose consumption rate and ${\small{D}}$-ribose production rate. Because the sum of the specific consumption rates for xylose and glucose was similar at all agitation speeds, metabolic preferences between xylose and glucose might depend on oxygen supply. Although B. subtilis SPK1 can take up xylose and glucose by the active transport mechanism, a high initial concentration of xylose and glucose was not beneficial for high ${\small{D}}$-ribose production.

• Microbiology and Biotechnology Letters
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• v.40 no.2
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• pp.163-167
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• 2012

Since D-xylose is not fermentable in Saccharomyces cerevisiae, its conversion to D-xylulose is required for its application in biotechnological industries using S. cerevisiae. In order to convert D-xylose to D-xylulose by way of an enzyme immobilized system, D-xylose isomerase (XI) of Escherichia coli was fused with 10-arginine tag (R10) at its C-terminus for the simple purification and immobilization process using a cation exchanger. The fusion protein XIR10 was overexpressed in recombinant E. coli and purified to a high purity by a single step of cation exchange chromatography. The purified XIR10 was immobilized to a cation exchanger via the electrostatic interaction with the C-terminal 10-arginine tag. Both the free and immobilized XIR10 exhibited similar XI activities at various pH values and temperatures, indicating that the immobilization to the cation exchanger has a small effect on the enzymatic function of XIR10. Under optimized conditions for the immobilized XIR10, D-xylose was isomerized to D-xylulose with a conversion yield of 25%. Therefore, the results of this study clearly demonstrate that the electrostatic immobilization of XIR10 via the interaction between the 10-arginine tag and a cation exchanger is an applicable form of the conversion of D-xylose to D-xylulose.

• Journal of Microbiology and Biotechnology
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• v.27 no.1
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• pp.77-83
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• 2017

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. Owing 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 ${\small{D}}$-xylose and then further convert the ${\small{D}}$-xylose into ${\small{D}}$-xylonic acid, a Department of Energy top-30 platform chemical. Four different types of enzymes (endoxylanase, ${\alpha}$-glucuronidase, ${\beta}$-xylosidase, and xylose dehydrogenase) were incorporated into the artificial complexes. We demonstrated that tethering our enzymes in a complex resulted in significantly more activity (up to 71%) than the same amount of enzymes free in solution. We also determined that varying the enzyme composition affected the level of complex-related activity enhancement as well as overall yield.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.12
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• pp.1773-1778
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• 2008

Two experiments were carried out to study the effects of corticosterone (CORT) administration on intestinal morphology and function of broilers. In both experiments, birds were randomly divided into two equal groups. One group was the control group (CTRL), and the birds were fed with a basal diet. The other was the experimental group (CORT), and the birds were fed with the basal diet plus 30 mg of CORT/kg diet. At 21 days of age, performance, morphological characteristics of intestine, D-xylose level in plasma, activities of digestive enzymes in digesta, digestibility of nutrients and 5-bromo-2-deoxyuridine (BrdUrd)-labeling index of intestinal epithelial cells were determined. CORT administration decreased feed intake, daily gain and feed conversion ratio (p<0.05). CORT also decreased duodenal and jejunal villus height (p<0.05) as well as crypt depth (p<0.05). The D-xylose level in plasma of CORT-treated broilers was lower than that of the control (p<0.05). CORT treatment caused a decrease in apparent digestibility of protein (p<0.05), whereas fat and starch apparent digestibilities were unaffected (p>0.05). CORT administration increased activities of trypsin and amylase (p<0.05), and decreased BrdUrd-labeling index of duodenal and jejunal epithelial cells (p<0.05). In conclusion, CORT administration impaired the normal morphology and absorptive capacity of the small intestine of broiler chickens.

• Journal of Microbiology and Biotechnology
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• v.13 no.4
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• pp.501-508
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• 2003

Artificial coupling of one enzyme with another can provide an efficient means for the production of industrially important chemicals. Xylose reductase has been recently discovered to be useful in the reductive production of xylitol. However, a limitation of its in vitro or in vivo use is the regeneration of the cofactor NAD(P)H in the enzyme activity. In the present study, an efficient process for the production of xylitol from D-xylose was established by coupling two enzymes. A NADH-dependent xylose reductase (XR) from Pichia stipitis catalyzed the reduction of xylose with a stoichiometric consumption of NADH, and the resulting cofactor $NAD^+$ was continuously re-reduced by formate dehydrogenase (FDH) for regeneration. Using simple kinetic analyses as tools for process optimization, suitable conditions for the performance and yield of the coupled reaction were established. The optimal reaction temperature and pH were determined to be about $30^{\circ}C$ and 7.0, respectively. Formate, as a substrate of FDH, affected the yield and cofactor regeneration, and was, therefore, adjusted to a concentration of 20 mM. When the total activity of FDH was about 1.8-fold higher than that of XR, the performance was better than that by any other activity ratios. As expected, there were no distinct differences in the conversion yields of reactions, when supplied with the oxidized form $NAD^+$ instead of the reduced form NADH, as a starting cofactor for regeneration. Under these conditions, a complete conversion (>99%) could be readily obtained from a small-scale batch reaction.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.2
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• pp.238-242
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• 2002

Seventy-four piglets were used to investigate the effects of dietary glutamine (Gln) and glutamate (Glu) on the mucosal structure and active absorption of small intestinal, DNA and RNA concentrations of skeletal muscle tissue in piglets during d 28 to 42 of age. Postweaning piglets were fed for 14 d corn- and soybean meal-based diets supplemented with 0.0 or 1.0% L-Gln or L-Glu. On d 7 and 14 postweaning, pigs' small intestinal sections and longissimus dorsi were collected, at the same time, the D-xylose absorption test was conducted. The results suggested that in comparison to control piglets, jejunal atrophy during the first week postweaning was prevented by the glutamine and glutamate supplementation (1%) and the capability of small intestine to absorb Dxylose was improved. Furthermore the RNA concentration in skeletal muscle tissue was increased. These results provide an experimental basis for use of glutamine and glutamate on alleviating the weaning stresses and improving piglets' growth performance.

• Korean Journal of Microbiology
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• v.31 no.2
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• pp.157-165
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• 1993

A 1, 4-.betha.-D-xylanase, designated as xylanase II, was purified from the culture filtrate of Trichoderma koningii ATCC 251131 by column chromatography on Sephadex G-75, SP-Sephadex C-50, DEAE-Sephadex A-50 and Sephadex G-50 with an overall yield of 6.97%. It has a molecular weight of 21.000 and an isoelectric point of 9.4. The enzyme activity is optimal at pH 5.0 and at a temperature of 50.deg.C. Xylanase II is stable up to 50.deg.C, while 40 and 90% of its activity are lost after the incubation for 30 and 60 min at 60.deg.C. The enzyme degrades xylan with relatively high activity, as well as carboxymethylcellulose and Avicel. Its $K_{m}$ values for oat-spelt xylan, larchwood xylan and Avicel are 7.48, 1.98 and 13.33 mg/ml, respectively. The hydrolysis products of oat-spelt xylan by xylanase II are xylose, xylobiose, xylotriose and arabinoxylotriose, while the reaction products of larchwood xylan are xylose, xylobiose, xylotriose and small amount of higher oligomers. The action paterns of the enzyme demonstrate that xylanase II is endo-enzyme.

• The Korean Journal of Food And Nutrition
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• v.28 no.5
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• pp.821-828
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• 2015

ASW0 is a polysaccharide derived from the perennial herb Aster scaber Thunberg. We isolated ASW0, a fraction of crude polysaccharide, by means of ethanol precipitation and dialysis after hot water extraction to investigate its physicochemical properties and immunostimulatory effects. ASW0 contains neutral sugar (45.7%), acidic sugar (51.6%), protein (2.3%), and 2-keto-3-deoxy-D-manno-octonate (KDO) (0.4%). The neutral sugar in ASW0 (in mole percentage) was mainly composed of arabinose (34.5 mol%), glucose (31.1 mol%), galactose (14.9 mol%), and rhamnose (8.1 mol%), which are characteristic of pectic polysaccharides. ASW0 also contained small amounts of xylose, mannose, and fucose. The anti-complementary activity of ASW-0 was similar to that of polysaccharide K (used as positive control). ASW0 exhibited no cytotoxicity in RAW 264.7 macrophages and dramatically increased nitric oxide (NO) production in a dose dependent manner ($0.3{\sim}30{\mu}g/mL$). Also, macrophages stimulated with ASW0 showed enhanced production of immunostimulatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor alpha ($TNF-{\alpha}$) in a dose dependent manner. These results suggest that the ASW0 have a potent immunostimulatory effect and can be used as a natural immune health ingredient.