Induction of aldose reductase activity inCandida guilliermondii by pentose sugars

Xylose reductase activity in Debaryomyces hansenii UFV-170 cultivated in semi-synthetic medium and cotton husk hemicellulose hydrolyzate

“…Such a role of D-xylose as the best inducer of XR activity is in accordance with other studies [8,[18][19][20].…”

“…Nevertheless, it seems possible to generalize that XR genes are regulated through catabolic repression by glucose, and in general the hexoses are the worst carbon sources [15]. D-Xylose was the best inducer also in C. guilliermondii [18,19,42] and C. tenuis [8], but satisfactory results were also obtained on L-arabinose. On the contrary, low activity was observed in the former yeast when cultivated on The maximum specific activities obtained on D-xylose in these phases (0.158 and 0.240 U mg -1 , respectively) were assumed as a reference (100%).…”

“…On the contrary, low activity was observed in the former yeast when cultivated on The maximum specific activities obtained on D-xylose in these phases (0.158 and 0.240 U mg -1 , respectively) were assumed as a reference (100%). The control medium did not contain any carbohydrate added to the basal medium D-glucose, D-mannose, D-galactose, cellobiose and D-fructose, likely due to catabolic repression [18,19]. Similarly, Pichia stipitis NRRL Y7124 and Pachysolen tannophilus NRRL Y2460 grown on glucose showed only 5-15% of the XR activity detected on xylose [17].…”

“…Several works showed that the expression of the XR gene is subject to regulation by induction and catabolite repression [8,[16][17][18][19]. D-Xylose is reported to be the best XR gene inducer, followed closely by L-arabinose [8,[18][19][20], which suggests that in general pentoses can be effective in the induction of XR gene.…”

“…Several works showed that the expression of the XR gene is subject to regulation by induction and catabolite repression [8,[16][17][18][19]. D-Xylose is reported to be the best XR gene inducer, followed closely by L-arabinose [8,[18][19][20], which suggests that in general pentoses can be effective in the induction of XR gene. Negligible activity has been detected with cellobiose, D-mannose, D-glucose, D-galactose, D-fructose and glycerol as substrates [8,19], thus suggesting that the XR gene expression is partially or practically suppressed (catabolite repression) on media containing these substrates [19][20][21].…”