半纤维素酶水解物木糖醇发酵酵母菌的筛选

Screening of yeast strains for xylitol production on hemicellulose enzymatic hydrolysate

对 7株酵母菌通过商品木糖培养基摇瓶初筛 ,选出热带假丝酵母 (Candidatropicalis )AY 91 0 0 9作为出发菌株进行驯化培养 ,结合木糖平板筛选出一株优良的木糖醇生产菌C .tropicalisLH - 0 81 ,并用其进行了玉米芯半纤维素酶水解物发酵制备木糖醇的初步试验。 2 5 0mL摇瓶发酵结果表明 ,当水解物中还原糖浓度为 1 5 .2 4 g/L ,装料量为 1 0 0mL ,初始 pH值5 .4 ,(2 8± 1 )℃培养 72h木糖醇浓度 2 .1 9g/L ,还原糖利用率 2 8.7% ,转化率 0 .5 0 g/g ;木糖转化率 0 .75 g/g ,达到理论转化率的 83.3%。

Candida tropicalis AY 91009 was selected by commercial xylose culture medium from seven yeast strains, which was then adapted to the corn cob hemicellulose enzymatic hydrolysate, and Candida tropicalis LH 081, a good xylitol producing strain, was developed and isolated by high concentration xylose plate. Primary study on xylitol fermentation on corn cob hemicellulose enzymatic hydrolysate was carried out using Candida tropicalis LH 081 by 250 mL flask batch fermentation process. The best results, a xylitol yield 0.50 g/g reducing sugar with a reducing sugar utilization efficiency of 28.7%, were achieved after 72 hours culture under the following conditions: reducing sugars concentration 15.24 g/L, loading volume 100 mL, initial pH value 5.4, 160 r/min in the first 24 hours and 100 r/min in the later at culture temperature (28±1)℃.