蒸汽爆破玉米秸秆的分段酶水解

Multi-stage Enzyme Hydrolysis of Steam-explored Corn Stover

以蒸汽爆破预处理的玉米秸秆为原料,探讨了分段酶水解和超滤回用β-葡萄糖苷酶的工艺对水解效果的影响。结果显示:三段酶解过程中由于反应产物纤维二糖和葡萄糖的及时移除,使产物对纤维素酶的抑制作用大大降低,提高了纤维素酶水解得率和纤维二糖转化为葡萄糖的效率,并且缩短反应时间。与一段酶水解工艺相比,(6+6+12)h三段酶水解蒸汽爆破玉米秸秆使纤维素水解得率从62.83%提高到70.16%,并且水解时间从72 h减少到24 h。蒸汽爆破玉米秸秆由23%的结晶区和77%的无定形区组成,经纤维素酶(6+6+12)h三段水解后,水解残渣在衍射角2θ为16°和22°处的两个衍射峰变得更加突出,衍射强度有所增强。用截留分子质量为30 ku的超滤膜回收水解液中的β-葡萄糖苷酶并进行下一轮酶解,回用第一轮β-葡萄糖苷酶的回收率为98.87%,葡萄糖的得率为92.71%;回用至第八轮β-葡萄糖苷酶的回收率为95.25%,葡萄糖的得率为90.87%。

With the steam-explored corn stover as the substrate, the effects of multi-stage hydrolysis and the reuse ofβ-glucosidases via ultrafiltration technique on enzymatic hydrolysis yield were investigated. The analysis results indicated that the removal of cellobiose and glucoseat each stage was benefit to improve the cellulase activities,the hydrolysis efficiency was enhanced and less hydrolysis time was obtained. Higher hydrolysis yield（ 70. 16%） was achieved as three-stage（ 6 ＋ 6 ＋ 12） h hydrolysis was used in 24 h in contrast to a 62. 84% yield in 72 h for one-stage hydrolysis. The steam-explored corn stover was composed by 23 % crystalline region and 77 % amorphous region. Two diffraction peaks of substrate at diffraction angle of 16°and 22° were prominent after the three-stage（ 6 ＋ 6 ＋ 12） h hydrolysis,and the diffraction intensity increased. The ultrafiltration technique with the 30 ku membrane was employed to recover the β-glucosidase. The glucose yield during the first round of hydrolysis was 92. 71%,and the β-glucosidase recovery rate was 98. 87%. During the 8th round of hydrolysis,the glucose yield and the β-glucosidase recovery rate were 90. 87% and 95. 25%,respectively.