Lignocellulosic biomass, which contains large amounts of glucose and xylose, is the new ideal feedstock for ethanol production used as renewable liquid fuel for transportation. The naturally occurring Saccharomyces yeasts traditionally used for industrial ethanol production are unable to ferment xylose. We have successfully developed genetically engineered Saccharomyces yeasts that can effectiv...

The effect of insulin administration upon D-xylose-1-C(14) penetration into the diaphragm and gastrocnemius muscles of functionally nephrectomized normal, hypophysectomized, and adrenalectomized rats has been examined. It was found in all groups that after the administration of tracer amounts of D-xylose, this sugar enters the cell water of diaphragm to a greater extent than in gastrocnemius mu...

Blood xylose concentrations were measured at 60, 90 and 120 min after 25 xylose was given orally in 33 well-nourished Papua New Guinean in-patients at Port Moresby; 12 had lepromatous (group A) and seven non-lepromatous (group B) leprosy, and 14 were controls (group C). Differences between mean xylose concentrations were not significant at any time interval. Three patients (two in group A and o...

BACKGROUND Efficient xylose alcoholic fermentation is one of the key to a successful lignocellulosic ethanol production. However, regulation of this process in the native xylose-fermenting yeasts is poorly understood. In this work, we paid attention to the transcriptional factor Cat8 and its possible role in xylose alcoholic fermentation in Ogataea (Hansenula) polymorpha. In Saccharomyces cerev...

We have identified and characterized the D-xylose transport system of Lactobacillus pentosus. Uptake of D-xylose was not driven by the proton motive force generated by malolactic fermentation and required D-xylose metabolism. The kinetics of D-xylose transport were indicative of a low-affinity facilitated-diffusion system with an apparent K(m) of 8.5 mM and a V(max) of 23 nmol min(-1) mg of dry...

Its metabolic characteristics suggest that Zymobacter palmae gen. nov., sp. nov. could serve as a useful new ethanol-fermenting bacterium, but its biotechnological exploitation will require certain genetic modifications. We therefore engineered Z. palmae so as to broaden the range of its fermentable sugar substrates to include the pentose sugar xylose. The Escherichia coli genes encoding the xy...

Native strains of Saccharomyces cerevisiae do not assimilate xylose. S. cerevisiae engineered for d-xylose utilization through the heterologous expression of genes for aldose reductase (XYL1), xylitol dehydrogenase (XYL2), and d-xylulokinase (XYL3 or XKS1) produce only limited amounts of ethanol in xylose medium. In recombinant S. cerevisiae expressing XYL1, XYL2, and XYL3, mRNA transcript leve...

BACKGROUND Xylose is the second most abundant carbohydrate in the lignocellulosic biomass hydrolysate. The fermentation of xylose is essential for the bioconversion of lignocelluloses to fuels and chemicals. However the wild-type strains of Saccharomyces cerevisiae are unable to utilize xylose. Many efforts have been made to construct recombinant yeast strains to enhance xylose fermentation ove...

During growth of the halophilic archaeon Haloarcula marismortui on D-xylose, a specific D-xylose dehydrogenase was induced. The enzyme was purified to homogeneity. It constitutes a homotetramer of about 175 kDa and catalyzed the oxidation of xylose with both NADP+ and NAD+ as cosubstrates with 10-fold higher affinity for NADP+. In addition to D-xylose, D-ribose was oxidized at similar kinetic c...

Fermentation of xylose is a fundamental requirement for the efficient production of ethanol from lignocellulosic biomass sources. Although they aggressively ferment hexoses, it has long been thought that native Saccharomyces cerevisiae strains cannot grow fermentatively or non-fermentatively on xylose. Population surveys have uncovered a few naturally occurring strains that are weakly xylose-po...