College of Resource and Environment, Sichuan Agricultural University, Chengdu Campus, 211 Huimin Road, Chengdu, 611130 Sichuan, China.
Appl Biochem Biotechnol. 2011 Oct;165(3-4):1024-36. doi: 10.1007/s12010-011-9317-9. Epub 2011 Jul 5.
Sweet sorghum bagasse (SSB) was steam pretreated in the conditions of 190 °C for 5 min to assess its amenability to the pretreatment and enzymatic hydrolysis. Results showed that pretreatment conditions were robust enough to pretreat SSB with maximum of 87% glucan and 72% xylan recovery. Subsequent enzymatic hydrolysis showed that the pretreated SSB at 2% substrate consistency resulted in maximum of 70% glucan-glucose conversion. Increasing substrate consistency from 2% to 16% led to a significant reduction in glucan conversion. However, the decrease ratio of glucan-glucose conversion was the minimum when the consistency increased from 2% to 12%. When the pretreated SSB consistency of 12% was applied for hydrolysis, increase in cellulase loading from 7.5 up to 20 filter paper units (FPU)/g glucan resulted only in 14% increase in glucan-glucose conversion compared to 20% increase with cellulase loading varying from 2.5 to 7.5 FPU/g glucan. More than 10 cellobiase units (CBU)/g glucan β-glucosidase supplementation had no noticeable improvement on glucan-glucose conversion. Additionally, supplementation of xylanase was found to significantly increase glucan-glucose conversion from 50% to 80% with the substrate consistency of 12%, when the cellulase and β-glucosidase loadings were at relatively low enzyme loadings (7.5 FPU/g and 10 CBU/g glucan). It appeared that residual xylan played a critical role in hindering the ease of hydrolysis of SSB. A proper xylanase addition was suggested to achieve a high hydrolysis yield at relatively high substrate consistency with relatively low enzyme loadings.
甜高粱蔗渣（SSB）在 190°C 下蒸汽预处理 5 分钟，以评估其对预处理和酶水解的适宜性。结果表明，预处理条件足够强大，可以以最大 87%的葡聚糖和 72%的木聚糖回收率对 SSB 进行预处理。随后的酶水解表明，在 2%底物浓度下，预处理的 SSB 可实现最大 70%的葡聚糖-葡萄糖转化率。将底物浓度从 2%增加到 16%会导致葡聚糖转化率显著降低。然而，当底物浓度从 2%增加到 12%时，葡聚糖-葡萄糖转化率的降低幅度最小。当应用 12%的预处理 SSB 进行水解时，将纤维素酶用量从 7.5 增加到 20 滤纸单位（FPU）/g 葡聚糖，仅导致葡聚糖-葡萄糖转化率增加 14%，而纤维素酶用量从 2.5 增加到 7.5 FPU/g 葡聚糖时，转化率增加 20%。每克葡聚糖添加超过 10 个纤维二糖酶单位（CBU）的β-葡萄糖苷酶对葡聚糖-葡萄糖转化率没有明显改善。此外，当纤维素酶和β-葡萄糖苷酶的用量处于相对较低的酶用量（7.5 FPU/g 和 10 CBU/g 葡聚糖）时，添加木聚糖酶可使 12%底物浓度下的葡聚糖-葡萄糖转化率从 50%显著提高到 80%。似乎残余木聚糖在阻碍 SSB 水解的容易程度方面起着关键作用。建议适当添加木聚糖酶，以在相对较高的底物浓度和相对较低的酶用量下实现高水解收率。
