INDUCTION OF ALDOSE REDUCTASE-ACTIVITY IN CANDIDA-GUILLIERMONDII BY PENTOSE SUGARS

Cell extracts of Candida guilliermondii grown in D-xylose, L-arabinose , D-galactose, D-glucose, D-mannose and glycerol as sole carbon source s possessed NADPH-dependent aldose reductase activity, but no NADH-dep endent activity was detected. D-xylose and L-arabinose were the best i nducers of aldose reductase activity. The highest enzyme activity in D -xylose or L-arabinose-grown cells was observed first with L-arabinose followed by D-xylose as substrates of the enzymatic reaction. However , only low activity was found in D-glucose, D-mannose and D-galactose- grown cells, indicating that these carbon sources cause catabolite rep ression. Enzyme activities induced in D-xylose-grown cells were twice as high as those obtained from the cells under resting conditions. Fur thermore, the level of induction of aldose reductase activity depended on the initial concentration of D-xylose. The present study shows tha t aldose reductase activity may be efficiently induced by pentose suga rs of hemicellulosic hydrolysates and weakly by hemicellulosic hexoses .