*2.5. Treatments and Supplementations of the Xylose-Rich Hydrolysates before Xylitol Fermentation*

The pHs of GRS/S and WB1/S were adjusted to 6 by adding Ca(OH)2, and the precipitated gypsum was removed by filtration (filter paper). In certain cases, the rice straw hydrolysate (GRS/S) was supplemented with 2 g/L ammonium-sulphate or peptone. A combined treatment of GRS/S including a clarification by activated carbon and a subsequent supplementation with 2 g/L peptone was also tested. The clarification was performed by using 5 *w*/*w*% activated carbon (Norit DX ULTRA 8005.3) for 30 min with continuous stirring. The activated carbon was then separated by filtration through paper filter. After the treatments described above, all of the hydrolysates were sterilized in autoclave at 121 ◦C for 20 min.

### *2.6. Inoculum Preparation*

A single colony of *Candida boidinii* NCAIM Y.01308 was transferred from the malt agar slants into glucose agar (1 *w/v*% glucose, 1 *w/v*% peptone, 0.3 *w/v*% yeast extract, and 2 *w/v*% agar) and propagated for three days at room temperature. Then the cells were transferred into the inoculum medium (pH 6) containing 10 g/L yeast extract, 15 g/L KH2PO4, 1 g/L MgSO4.7H2O, 3 g/L (NH4)2HPO4, and 30 g/L xylose. The cells were propagated in the inoculum medium for 72 h at 220 rpm and 30 ◦C.
