Effect of inoculum level on xylitol production from rice straw hemicellulose hydrolysate byCandida guilliermondii

Abstract

The effect of inoculum level on xylitol production byCandida guilliermondii was evaluated in a rice straw hemicellulose hydrolysate. High initial cell density did not show a positive effect in this bioconversion since increasing the initial cell density from 0.67 g L⁻¹ to 2.41 g L⁻¹ decreased both the rate of xylose utilization and xylitol accumulation. The maximum xylitol yield (0.71 g g⁻¹) and volumetric productivity (0.56 g L⁻¹ h⁻¹) were reached with an inoculum level of 0.9 g L⁻¹. These results show that under appropriate inoculum conditions rice straw hemicellulose hydrolysate can be converted into xylitol by the yeastC. guilliermondii with efficiency values as high as 77% of the theoretical maximum.