Pentose Metabolism by Candida utilis

Abstract

Xylose isomerase, an enzyme isomerizing xylose to xylulose, was produced adaptively when Can dida utilis, a fodder yeast, was grown in a medium containing xylose. This experiment was carried out in order to isolate and purify the enzyme, and to clarify properties of the enzyme. As a result, it was revealed that the enzyme could be solubilized by plasmolysis, and was purified by dialysis, salting out with ammonium sulfate, precipitating with acetone, and adsorbing to calcium phosphate gel. The enzyme requires some divalent metal ions for its action and among them manganese ion is the most effective. The enzyme is inhibited particularly by ethylenediamine-tetraacetic acid and has somewhat thermotolerant character.

Xylitol dehydrogenase mutants ofPachysolen tannophilusand the role of xylitol in d-xylose catabolism

“…Extracts of cells grown on 2% D-xylose possessed activity for both o-xylose reductase and xylitol dehydrogenase ( Table 1). The cofactor preferences, NADPH with D-xylose reductase and NAD with xylitol dehydrogenase, were in agreement with data from other organisms [5,6]. The levels of activity were lower on cells grown on 2% xylitol.…”

“…However, evidence has been presented that in some yeasts D-xylose is converted to D-xylulose in a single step via D-xylose isomerase [6,7]. Involvement of D-xylose dehydrogenase is also conceivable, because a Pichia species produced D-xylonic acid from D-xylose, presumably via D-xylonolactone [8].…”

Identification in the Mold Hypocrea jecorina of the First Fungal d-Galacturonic Acid Reductase

“…D-Xylose for example is catabolized in bacteria through a path consisting of xylose isomerase and xylulokinase (21), whereas in fungi, the path consists of xylose reductase, xylitol dehydrogenase, and xylulokinase (22). Another example is L-arabinose catabolism.…”

Xylitol Production byEnterobacter liquefaciens

“…The isomerization of D-xylose by D-xylose isomerase has been found to occur in various bacteria, [12][13][14][15][16][17][18][19] and in addition this enzyme has also been detected in a few yeasts such as Candida utilis 20 ) and Rhodotorula gracilis. 21 ) On the other hand, NADPH-dependent D-xylose reductase which participated in the reduction ofD-xylose to xylitol has been found exclusively in fungi and yeasts.…”