Temperature sensitivity of the induction of xylose reductase in Pachysolen tannophilus.

Pachysolen tannophilils is a yeast capable of fermenting xylose to ethanol. I,Z This organism is of interest due to its potential for converting the xylose found in agricultural and forestry residues to ethanol. Hemicellulosic sugars (i.e., xylose) are relatively abundant in certain plant residues and can be isolated with relative ease (for review, see ref. 3). The assumed pathway of xylose utilization in P, tannophilils involves NADPH-dependent xylose reductase, converting xylose to xylitol, followed by the conversion of xylitol to xylulose by NAD-dependent xylitol dehydrogenase. 6 Both enzymes are induced in the presence ofxylose.,7 Under anaerobic conditions, NADH may serve as the cofactor for xylose reductase. The presence and induction of these enzymes has been reported in other fungi, including Candida and Penicillillm. However, certain bacteria and yeasts 11 ,IZ