[Utilization of sugar cane bagasse hydrolysates for xylitol production by yeast]

The effects of the concentration of sulfuric acid and the ratio of liquid to solid on xylose yield from sugar cane bagasse in its hemicellulose hydrolysis process were studied with the Quadratic Rotary Combination Design. Regression analysis showed that there was a marked regression relationship between the two factors and xylose yield. As the result of optimizing the hydrolysis conditions by regression equation, xylose yield of 24 g/100 g sugar cane bagasse was obtained when sulfuric acid concentration was 2.4 g/L and liquid to solid ratio was 6.2 under the conditions of stream pressure of 2.5 x 10(4) Pa and hydrolysis time of 2.5 h. The macroporous resin adsorption was proved to be a good method to reduce the concentration of yeast cell growth inhibitor in sugar cane bagasse hemicellulose hydrolysate and to enhance the hydrolysate fermentability. The hydrolysate treated with macroporous resin adsorption under pH2 was used as the substrate for xylitol production by a xylitol-producting yeast, Candida tropicalis AS2.1776. At an initial xylose concentration of 200 g/L, all xylose was consumed within 110 h with a xylitol production rate of 1.15 g/L.h, and a xylitol yield of 0.64 g/g xylose.