In recombinant, xylose-fermenting Saccharomyces cerevisiae, about 30% of the consumed xylose is converted to xylitol. Xylitol production results from a cofactor imbalance, since xylose reductase uses both NADPH and NADH, while xylitol dehydrogenase uses only NAD(+). In this study we increased the ethanol yield and decreased the xylitol yield by lowering the flux through the NADPH-producing pent...

Optimization of the culture medium and process variables for xylitol production using corncob hemicellulose hydrolysate by Pachysolen tannophilus (MTTC 1077) was performed with statistical methodology based on experimental designs. The screening of nine nutrients for their influence on xylitol production was achieved using a Plackett-Burman design. Peptone, xylose, MgSO4·7H2O, and yeast extract...

Xylitol dehydrogenase (XDH) is one of the key enzymes in d-xylose metabolism, catalyzing the oxidation of xylitol to d-xylulose. Two copies of the XYL2 gene encoding XDH in the diploid yeast Candida tropicalis were sequentially disrupted using the Ura-blasting method. The XYL2-disrupted mutant, BSXDH-3, did not grow on a minimal medium containing d-xylose as a sole carbon source. An enzyme assa...

Microorganisms capable of producing xy]itol from Darabitol were screened for. Of the 420 strains tested, three bacteria, belonging to the genera Acetobacter and Gluconobacter, produced xylitol from D-arabitol when intact cells were used as the enzyme source. Among them, Gluconobacter oxydans ATCC 621 produced 29.2 g!1 xylitol from 52.4 g!1 D-arabitol after incubation for 27 h. The production of...

Sustainable biofuel production from renewable biomass will require the efficient and complete use of all abundant sugars in the plant cell wall. Using the cellulolytic fungus Neurospora crassa as a model, we identified a xylodextrin transport and consumption pathway required for its growth on hemicellulose. Reconstitution of this xylodextrin utilization pathway in Saccharomyces cerevisiae revea...

Rusks are mostly used at breakfast in Asian countries like India and Pakistan. Effect of replacement of xylitol on physicochemical and sensory parameters of rusks at various levels of sugar replacement from 0100% was studied. Physicochemical and sensory characteristics were studied at storage intervals of 0, 10, 20 and 30 days to find out the best treatment for mass production. The moisture con...

Sweeteners are divided by their sources into natural and synthetic and by their nutritional values into nutritive and non-nutritive. Xylitol is a five carbon natural sweetener found in fibrous vegetables and fruit, which offers many health benefits to human. On oral health xylitol prevents dental caries, retards demineralization of tooth enamel, promotes remineralization of tooth enamel, increa...

The xylose-fermenting recombinant Saccharomyces cerevisiae and its improvement have been studied extensively. The redox balance between xylose reductase (XR) and xylitol dehydrogenase (XDH) is thought to be an important factor in effective xylose fermentation. Using protein engineering, we previously successfully reduced xylitol accumulation and improved ethanol production by reversing the depe...

Xylitol was produced by Candida guilliermondii from charcoal-treated and untreated rice straw hemicellulosic hydrolysate with or without nutrients (ammonium sulphate, calcium chloride, rice bran extract). Both, xylitol yield and volumetric productivity decreased significantly when the nutrients were added to treated and untreated hydrolysates. In the treated hydrolysate, the efficiency of xylos...

Xylitol, a natural compound classified as sugar alcohol, is found diversely in fruits and vegetables small quantities. Commercial production of xylitol has expanded due to its health benefits wide applications an alternative sweetener food pharmaceutical products. Production on large scale industrially being achieved by the chemical method. However, biotechnological method offers possibilities ...