TO THE EDITOR: To Drs. Bonnema and colleagues, thank you for your comments on our recent article in AJP-Endocrinology and Metabolism (4). Indeed, for subjects not used to these polyols, 50 g of xylitol and 75 g of erythritol as a single bolus given within 2 min seems rather high. From a nutritional point of view the applied doses makes sense, at least in adapted subjects. This would then, for i...

Xylose reductase (XR) is a key enzyme in D-xylose metabolism, catalyzing the reduction of D-xylose to xylitol. An NADH-preferring XR was purified to homogeneity from Candida parapsilosis KFCC-10875, and the xyl1 gene encoding a 324-amino-acid polypeptide with a molecular mass of 36,629 Da was subsequently isolated using internal amino acid sequences and 5' and 3' rapid amplification of cDNA end...

The influence of temperature between 283 and 313 K on the fermentation of d-xylose with Pachysolen tannophilus ATTC 32691 to produce ethanol and xylitol was studied. All experiments were made in a batch-culture reactor keeping the aeration level constant and the pH of the culture medium at 4.5. In each experiments the maximum specific net growth rate (μm), biomass productivity (b), the specific...

Production of several yeast products occur in presence of mixtures of monosaccharides. To study effect of xylose and glucose mixtures with system aeration and nitrogen source as the other two operative variables on xylitol production by Pichia guilliermondii, the present work was defined. Artificial Neural Network (ANN) strategy was used to athematically show interplay between these three c...

Although β-xylosidases with xylanase activity are preferential for the hydrolysis of xylan and production xylitol, reports on their use scarce. In this study, a multifunctional β-xylosidase (XYL4) was identified. addition to activity, XYL4 also exhibited low α-arabinosidase activity. The enzyme able hydrolyze bagasse xylan, oat spelt birchwood beechwood corncob showed highest xylan. Structural ...

In this study, the optimization of different process variables-pH (4-6), aeration rate (200-550 rpm) and agitation rate (0.6-1.8 vvm) were investigated using rotating simplex method and uniform design method to enhance xylitol production from xylose by D. nepalensis in a batch stirred tank bioreactor. Maximum xylitol productivity (0.576 g L-1 h-1) was obtained at pH 4.0, agitation 300 rpm and a...

Glucose is a cheap and readily available substrate for production of large-scale chemicals. Synthesis xylitol, high demand chemical in global market currently done by using xylose, which contributes to its operational cost. Studies on xylitol from glucose have explored several approaches, sequential fermentation multiple single gene expression. Xylitol-5-phosphate dehydrogenase (XPDH), an enzym...

Sugar alcohols find applications in pharmaceuticals, oral and personal care products, and as intermediates in chemical synthesis. While industrial-scale production of these compounds has generally involved catalytic hydrogenation of sugars, microbial-based processes receive increasing attention. The past few years have seen a variety of interesting metabolic engineering efforts to improve the c...

Xylitol dehydrogenase (EC1.1.1.9) from xylose-grown cells of Candida shehatae was purified 215-fold by sequential chromatography on NADC8 affinity, Superose-12, and Cibacron blue columns, and a single band was observed by SDS gel electrophoresis. The purified enzyme had a native molecular weight of 82 kDa and a denatured molecular weight of 40 kDa following SDS gel electrophoresis, indicating t...

Recent years have seen an increase in the use of lignocellulosic materials in the development of bioproducts. Because sisal fiber is a low cost raw material and is readily available, this work aimed to evaluate its hemicellulose fraction for the simultaneous production of xylitol and ethanol. The sisal fiber presented a higher hemicellulose content than other frequently-employed biomasses, such...