This study reports an industrially applicable non-sterile xylitol fermentation process to produce xylitol from a low-cost feedstock like corn cob hydrolysate as pentose source without any detoxification. Different immobilization matrices/mediums (alginate, polyvinyl alcohol, agarose gel, polyacrylamide, gelatin, and κ-carrageenan) were studied to immobilize Candida tropicalis NCIM 3123 cells fo...

The authors declare no conflict of interest. The caries-controlling or preventing effect of xylitol is more than just excluding fermentable sugars from the diet. This review aims to discuss the specific effects of xylitol which could have contributed to the results of the caries trials. Xylitol promotes mineralization by increasing the flow of saliva, an effect it has in common with all sweeten...

NADPH regeneration is a limiting factor in reduction of xylose to xylitol in C. tropicalis. The oxidative PPP is the major source of NADPH biosynthesis in yeast. To enhance metabolic flux through PPP for promotion of NADPH regeneration. Genes involoved in EMP pathway were engineered by sequencial disruption and over-expression. For this, several genes involves in EMP pathway and promoters were ...

Xylitol metabolism and its interaction with lactate metabolism has been investigated in perfused livers from fasted rats. Xylitol (5 mM) served as a strong reductant for cytosolic NAD systems as shown by increased ratios of lactate to pyruvate, a-glycerophosphate to dihydroxyacetone-P, and triose phosphates to 3-P-glycerate. The mitochondrial NAD system, as monitored by changes of the fl-hydrox...

Whole cells and a cell extract of Pachysolen tannophilus converted xylose to xylitol, ethanol, and CO(2). The whole-cell system converted xylitol slowly to CO(2) and little ethanol was produced, whereas the cell-free system converted xylitol quantitatively to ethanol (1.64 mol of ethanol per mol of xylitol) and CO(2). The supernatant solution from high-speed centrifugation (100,000 x g) of the ...

due to the widespread applications of xylitol dehydrogenase, an enzyme used for the production of xylitol, the present study was designed for the cloning of xylitol dehydrogenase gene from glcunobacter oxydans dsm 2003. after extraction of genomic dna from this bacterium, xylitol dehydrogenase gene was replicated using polymerase chain reaction (pcr). the amplified product was entered into ptz5...

The production of xylitol from concentrated synthetic xylose solutions (S(o) = 130-135 g/L) by Debaryomyces hansenii was investigated at different pH and temperature values. At optimum starting pH (pH(o) = 5.5), T = 24 degrees C, and relatively low starting biomass levels (0.5-0.6 g(x)/L), 88% of xylose was utilized for xylitol production, the rest being preferentially fermented to ethanol (10%...

The ability of five yeast strains (locally isolated) to ferment xylose to xylitol were screened using a corn cobs hydrolysate. Candida tropicalis proved to be the best producer. The effects of culture conditions, namely initial pH, nitrogen source and yeast extract concentration on xylitol production were evaluated. The conditions for batch production of xylitol, using C. tropicalis immobilized...

Xylitol production was compared in fed batch fermentation by Saccharomyces cerevisiae strains overexpressing xylose reductase (XR) genes from Candida tropicalis, Pichia stipitis, Neurospora crassa, and an endogenous gene GRE3. The gene encoding a xylose specific transporter (SUT1) from P. stipitis was cloned to improve xylose transport and fed batch fermentation was used with glucose as a cosub...