Cofactor Engineering for Xylitol Production in Recombinant Saccharomyces cerevisiae

2 Cofactor Engineering for Xylitol Production in Recombinant Saccharomyces cerevisiae 

Cofactors such as NADP(H), NAD(H), vitamins, and coenzymes play many roles in the control of energy balance, enzyme reactions, protein structure, and so on. As a proton donor, xylose reductase (XR) requires 1 mole of NAD(P)H for the conversion of 1 mole of xylose to xylitol (Rizzi et al., 1988). As mentioned above, most xylose reductases prefer NADPH to NADH. To supply NADPH sufficiently, genes coding for metabolic enzymes directly or indirectly engaged in NADPH regeneration were overexpressed in recombinant S. cerevisiae expressing the XYLl gene. 

Glcose-6-phosphate is a key metabolite in the sugar metabolism and located at a fork to the glycolysis and pentose phosphate pathway. Reduction of the carbon flux 

Host strain Genetic manipulation Culture type Initial carbon source Leeding solution Xylitol concentration (g/L) Xylitol productivity (g/L-h) Xylitol yield (g/g. %) Reference 

15 Episomal expression of XYLl Glucose- limited fed-batch 47 g/L xylose 50 g/L glucose xylose, glucose (composition not given) 105.2 1.69 95 Lee et al. (2000) 

---