固定化热带假丝酵母发酵氨浸稻秸水解液生产木糖醇

采用海藻酸钙固定化热带假丝酵母细胞发酵氨水浸泡稻秸半纤维素水解液生产木糖醇。为了提高木糖醇的转化率,对发酵条件进行了研究。发酵在250 mL锥形瓶中进行。向水解液中补充适量氮源和营养盐等营养物质提高了木糖醇的生产速率,但木糖醇转化率没有因此而提高。适宜的初始pH和细胞干浓度分别为4-5和1.22 g/L。在这些条件下,进行了固定化细胞重复法较高浓缩度水解液的试验。结果发现,固定化细胞能在初始木糖浓度为104.2 g/L的水解液中重复批式发酵5次,木糖醇平均得率和生产速率分别为0.737 g/g和0.533 g/(L.h)。

Xylitol Production by Candida tropicalis from Hemicellulosic Hydrolysate of Ammonia Steeped Rice Straw

Xylitol was produced from hemicellulosic hydrolysate of rice straw by calcium alginate-immobilized C.tropicalis.In order to increase the xylitol yield,the conditions of fermentation were investigated.The fermentations were conducted in 250 mL flasks.As a result,xylitol yield was increased by the supplementation of appropriate nitrogen source,but the volumetric productivity was not enhanced.The feasible initial pH and initial dry cell concentration were 4～5 and 1.22 g/L,respectively.Under these conditions,repeated batch fermentations were performed by the immobilized cells in the highly concentrated hydrolysates. The cells could ferment repeatedly the hydrolysate with initial xylose concentration of 104.2 g/L for 5 batches,and the average yield and volumetric productivity were 0.737 g/g and 0.533 g/(L·h),respectively.