Dai Yongyong, Hu Bing, Yang Qiaomei, Nie Longhui, Sun Dan
School of Materials and Chemical Engineering, Hubei University of Technology, Wuhan, People's Republic of China.
College of Plant science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China.
Biotechnol Appl Biochem. 2022 Apr;69(2):548-557. doi: 10.1002/bab.2131. Epub 2021 Mar 18.
Miscanthus is regarded as a desired bioenergy crop with enormous lignocellulose residues for biofuels and other chemical products. In this study, the effect of different pretreatments (including microwave, NaOH, CaO, and microwave + NaOH/CaO) on sugar yields was investigated, leading to largely varied hexose yields at 4.0-73.4% (% cellulose) released from enzymatic hydrolysis of pretreated Miscanthus residues. Among them, the highest yield of 73.4% for hexoses was obtained from 12% NaOH (w/v) solution pretreatment, whereas 1% CaO (w/w) and microwave pretreatment resulted in a lower hexose yield than the control (without pretreatment). The sugar yield from microwave followed with 1% NaOH pretreatment was 4.3 times higher than that of microwave followed with 1% CaO. However, the enzymatic hydrolysis efficiencies of the sample were 15.2% and 58.5% under microwave pretreatment followed by 12% NaOH or 12.5% CaO, respectively, which were lower than those of the same concentration of alkali (NaOH and CaO) pretreatments. To investigate the mechanism of varied enzymatic saccharification under different pretreatments, the changes in the surface structure and porosity of the Miscanthus-pretreated lignocelluses were studied by means of Fourier transform infrared, Congo red staining, and scanning electron microscopy analysis. The results show that the different pretreatments destroy the cell wall cladding structure and reduce the bonding force between cellulose, hemicellulose, and lignin to different degrees, therefore increasing the accessibility of cellulose and enhancing cellulose digestion.
芒草被视为一种理想的生物能源作物，其含有大量用于生产生物燃料和其他化学产品的木质纤维素残渣。在本研究中，研究了不同预处理（包括微波、氢氧化钠、氧化钙以及微波 + 氢氧化钠/氧化钙）对糖产量的影响，预处理后的芒草残渣经酶解后释放的己糖产量在4.0 - 73.4%（%纤维素）之间，差异很大。其中，12%氢氧化钠（w/v）溶液预处理获得的己糖产量最高，为73.4%，而1%氧化钙（w/w）和微波预处理导致的己糖产量低于对照（未预处理）。微波后接1%氢氧化钠预处理的糖产量比微波后接1%氧化钙的高4.3倍。然而，在微波预处理后分别接12%氢氧化钠或12.5%氧化钙时，样品的酶解效率分别为15.2%和58.5%，低于相同浓度碱（氢氧化钠和氧化钙）预处理的酶解效率。为了研究不同预处理下酶促糖化变化的机制，通过傅里叶变换红外光谱、刚果红染色和扫描电子显微镜分析研究了预处理后的芒草木质纤维素的表面结构和孔隙率变化。结果表明，不同预处理不同程度地破坏了细胞壁包被结构，降低了纤维素、半纤维素和木质素之间的结合力，从而增加了纤维素的可及性并增强了纤维素消化。
