초록
<P>Previous results showed that an indigenously isolated yeast strain of <I>Candida tropicalis</I> was found to produce 12.11 g/L of xylitol under unoptimized conditions in presence of 50 g/L of xylose. In the present study, optimizing the process using one-variable at-a-time resulted in the production of 59.07 g/L of xylitol in 96 h in presence of 100 g/L xylose. Further optimization using response surface methodology led to the production of 65.45 g/L in medium containing 100 g/L xylose, 0.5% yeast extract, 0.03% MgSO<SUB>4</SUB>.7H<SUB>2</SUB>O and 0.2% KH<SUB>2</SUB>PO<SUB>4</SUB>, pH-4.5, 30 °C, 200 r/min for 96 h with 4% inoculum level. Addition of 1% methanol in response surface methodology optimized–medium led to the production of 67.12 g/L. Scaling up in 10 L fermentor resulted in productivity of 0.80 g/Lh with yield of 0.68 g/g. Efficient synthesis of xylitol esters was achieved with butyric acid (50.32%) and caproic acid (38.36%) in 4 h using <I>Pseudomonas aeruginosa</I> lipase in t-butanol: tetrahydrofuran (1:1 v/v).</P>