以玉米芯为原料酶法制备木糖条件的研究

On the enzymatic hydrolysis of the corn cob for xylose production

为使玉米芯中的木聚糖彻底降解为木糖，采用高压灭菌和蒸汽爆破预处理玉米芯粉，加入不同酶液（4IU／mg，以木聚糖酶为标准）后将预处理样在40℃下酶解24h。TIC检测结果表明，酶解产物主要为木糖，其中青霉（Penicillium decumbens）6号对1．01×10^6Pa下汽爆（干粉）样酶解后的木糖得率达33％；黑曲霉（A最rgillus niger）2107对120℃下高压灭菌样酶解后的木糖得率为19．5％；黑曲霉30197酶液对1．01×10^6Pa下汽爆（干粉）样酶解后的木糖得率为26．7％。研究表明，采用黑曲霉酶液对预处理后玉米芯进行酶解来制备木糖的方法可行。

This paper intends to introduce our newly developed method to make corn cob release totally its xylose by enzymatic hydrolysis. For this purpose, we have adopted 4 pretreatment methods shown as follows： （1） Put the corn cob autoclaving at 120 ℃ for 2 h; （2） The steam explosion treatment is done at 1.01 × 10^6 Pa （dry powder）, at 2.02× 10^6 Pa （dry powder mass：H2O volume = 1 g：2 mL）, and at 20 atm （dry powder：0.1% sulfuric acid= 1 g：2 mL）. Till now, all the pretreated corn cobs were incubated with different enzymes （4 IU/mg, taking xylanase as a standard） at 40 ℃ for 24 h and the xylose released at intervals can then be determined. The results of our experiments have shown that the maximum xylose yield was 33 %, which was obtained with the steam explosion pretreatment at 1.01 × 10^6 Pa （dry powder） by Penicillium decumbens 6. Yet as the xylanase from PeniciUium decumbens 6 had a low activity, a large amount of Penicillium decumbens 6 was needed. AS for the autoclaving of the pretreated corn cob, the xylanase from Aspergillus niger 2107 has achieved the xylose yield of 19.5%. While the xylanase from Aspergillus niger 30197 showed a better hydrolysis result on the corn cobs after the steam explosion pretreatment than the autoclaving pretreatment, with the xylose yields going up to 26.7%, 27.7%, and 29.6% respectively to the steam explosion pretreatment at 1.01 x 106 Pa （dry power）, at 2.02 × 10^6 Pa （dry powder mass： H20 volume= 1 g：2 mL）, and at 2.02 × 10^6 Pa （dry powder mass：0.1% sulfuric acid volume = 1 g：2 mL）. The hydrolysates were assayed by thin-layer chromatography and xylose was found to be the major end product. Investigations of enzyme components of different xylanases prove to account for their different hydrolysis results.