酵母发酵蔗渣半纤维素水解物生产木糖酶

采用二次正交旋转组合设计研究了蔗渣半纤维素水解过程中硫酸浓度与液 固比对木糖收率的影响。回归分析表明 ,这两个因素与木糖的收率之间存在显著的回归关系。通过回归方程优化水解条件 ,当硫酸浓度 2 .4g L ,液 固 =6 .2 ,在蒸汽压力 2 .5× 10 4Pa的条件下水解 2 .5h ,10 0g蔗渣可水解生成木糖约 2 4g。大孔树脂吸附层析处理蔗渣半纤维素水解物 ,能有效地减少其中的酵母生长抑制物含量 ,显著改善水解物的发酵性能。用大孔树脂在pH 2条件下处理过的蔗渣半纤维素水解物作基质 ,含木糖 2 0 0g L ,产木糖醇酵母菌株CandidatropicalisAS2 .1776发酵 110h耗完基质中的木糖 ,生成木糖醇 12 7g L ,产物转化率 0 .6 4(木糖醇g 木糖g) ,产物生成速率 1.15g L·h .

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.