Effects of environmental conditions on xylose reductase and xylitol dehydrogenase production by Candida guilliermondii.
The effects of environmental conditions, namely initial pH (2.5-7.0) and temperature (25 and 35 degrees C), on xylose reductase and xylitol dehydrogenase levels, as well as on xylitol production, were evaluated. Although the fermentative parameter values increased with an increase in pH and temperature (the maximum Yp/s and Qp were 0.75 g/g and 0.95 g/[L.h], respectively, both attained at pH 6.0, 35 degrees C), the highest xylose reductase activities (nearly 900 IU/mg of protein) were observed at an initial pH varying from 4.0 to 6.0. Xylitol dehydrogenase was favored by an increase in both initial pH and temperature of the medium. The highest xylitol dehydrogenase specific activity was attained at pH 6.5 and 35 degrees C (577 IU/mg of protein).
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Departmento Tecoologia Bioquimico-Farmaccutica, FCF, Universidade de Sao Paulo, Brazil.
Vitolo
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Felipe
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MG
Silva
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D000449:Aldehyde Reductase / Q000096:biosynthesis / Q000378:metabolism*; D002175:Candida / Q000201:enzymology* / Q000254:growth & development; D002474:Cell-Free System; D002482:Cellulose; D050542:D-Xylulose Reductase; D005285:Fermentation; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D013401:Sugar Alcohol Dehydrogenases / Q000096:biosynthesis / Q000378:metabolism*; D013696:Temperature
D002482:Cellulose; C027433:bagasse; D013401:Sugar Alcohol Dehydrogenases; D000449:Aldehyde Reductase; D050542:D-Xylulose Reductase; D006026:Glycoside Hydrolases; C023305:hemicellulase