The purpose of this work was to investigate the effects of xylose concentration (Sx 50.0 to 275.0 gL-1) and glucose/xylose ratio (Sg/Sx 0.09, 0.25 and 0.50) on the fermentative behavior of Debaryomyces hansenii UFV-170. The maximum cell productions expressed as cell dry weight were 40.28 gL-1 on pure xylose (Sx=275.0 gL-1) and 31.29 gL-1 on the glucose/xylose mixture (Sg 5.0 gL-1/Sx 50.0 gL-1), respectively. The highest xylitol concentration (130.43 gL-1) was obtained at Sx 190.0 gL-1 corresponding to a xylitol yield (YXyt/S) of 0.77 gg-1, volumetric productivity (QXyt) of 0.54 gL-1h-1 and specific productivity (qXyt) of 0.16 mmolg-1h-1. High xylose levels (Sx≥187.0 gL-1) did not increase xylitol accumulation, but stimulated ethanol production. An increase in Sg/Sx ratio from 0.09, 0.25 enhanced xylitol production at Sx 50.0 gL-1, but not at Sx 100.0 gL-1. In the simultaneous presence of glucose and xylose, the maximum xylitol accumulations (36.54 and 57.13 gL-1) was observed for Sg 14.0 gL-1/Sx 50.0 gL-1 with YXyt/S=0.72, QXyt=0.36 and qXyt=0.08. At the selected glucose/xylose ratio, glycerol and ethanol formed as by-products.
Bioconversíon de xilosa y glucosa-xilosa por Debayomyces hansenii
CONVERTI, ATTILIO;
2014-01-01
Abstract
The purpose of this work was to investigate the effects of xylose concentration (Sx 50.0 to 275.0 gL-1) and glucose/xylose ratio (Sg/Sx 0.09, 0.25 and 0.50) on the fermentative behavior of Debaryomyces hansenii UFV-170. The maximum cell productions expressed as cell dry weight were 40.28 gL-1 on pure xylose (Sx=275.0 gL-1) and 31.29 gL-1 on the glucose/xylose mixture (Sg 5.0 gL-1/Sx 50.0 gL-1), respectively. The highest xylitol concentration (130.43 gL-1) was obtained at Sx 190.0 gL-1 corresponding to a xylitol yield (YXyt/S) of 0.77 gg-1, volumetric productivity (QXyt) of 0.54 gL-1h-1 and specific productivity (qXyt) of 0.16 mmolg-1h-1. High xylose levels (Sx≥187.0 gL-1) did not increase xylitol accumulation, but stimulated ethanol production. An increase in Sg/Sx ratio from 0.09, 0.25 enhanced xylitol production at Sx 50.0 gL-1, but not at Sx 100.0 gL-1. In the simultaneous presence of glucose and xylose, the maximum xylitol accumulations (36.54 and 57.13 gL-1) was observed for Sg 14.0 gL-1/Sx 50.0 gL-1 with YXyt/S=0.72, QXyt=0.36 and qXyt=0.08. At the selected glucose/xylose ratio, glycerol and ethanol formed as by-products.
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