Yu Guang, Liu Shiyue, Feng Xiaoyan, Zhang Yuedong, Liu Chao, Liu Ya-Jun, Li Bin, Cui Qiu, Peng Hui
CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Engineering Laboratory of Single Cell Oil, Dalian National Laboratory for Clean Energy, Qingdao Institute of Bioenergy and Bioprocess Technology Chinese Academy of Sciences Qingdao 266101 China
University of Chinese Academy of Sciences Beijing 100049 China.
RSC Adv. 2020 May 1;10(29):17129-17142. doi: 10.1039/d0ra01759k. eCollection 2020 Apr 29.
The properties of lignocellulosic substrates obtained from different pretreatments have a big impact on downstream saccharification based on both the fungal cellulase system and the cellulosome-based whole-cell biocatalysis system. However the corresponding effect of these two distinct saccharification strategies has not been comparatively analyzed. In this work, three ammonium sulfite (AS)-based pretreatment combinations (, AS + hydrothermal (HT) pretreatment, AS + xylanase (X) pretreatment, and HT + AS pretreatment) were conducted to treat wheat straw. The obtained pretreated substrates with different properties were saccharified using fungal cellulase or an engineered strain as the whole-cell biocatalyst, and the ability to release sugar was comparatively evaluated. It was found that for the whole-cell saccharification, the total sugar digestibility of AS + HT/X pretreated wheat straw was 10% higher than that of HT + AS pretreated wheat straw. However, for fungal cellulase-based saccharification, the enzymatic hydrolysis efficiency was less susceptible to the sequence of pretreatment combinations. Hence, the whole-cell biocatalysis system was more sensitive to substrate accessibility compared to the free enzymes. In addition, the characterization and analyses showed that AS + HT/X pretreatment could remove more lignin, generating a more accessible surface with a larger external surface and lower surface lignin coverage, compared to the HT + AS pretreatment. Therefore, the AS + HT/X pretreatment was more compatible with the cellulosome-based whole-cell saccharification.
从不同预处理获得的木质纤维素底物的性质，对基于真菌纤维素酶系统和基于纤维小体的全细胞生物催化系统的下游糖化过程有很大影响。然而，尚未对这两种不同糖化策略的相应效果进行比较分析。在本研究中，采用三种基于亚硫酸铵（AS）的预处理组合（AS + 水热（HT）预处理、AS + 木聚糖酶（X）预处理和HT + AS预处理）来处理小麦秸秆。使用真菌纤维素酶或工程菌株作为全细胞生物催化剂，对获得的具有不同性质的预处理底物进行糖化，并比较评估其释放糖的能力。结果发现，对于全细胞糖化，AS + HT/X预处理的小麦秸秆的总糖消化率比HT + AS预处理的小麦秸秆高10%。然而，对于基于真菌纤维素酶的糖化，酶水解效率对预处理组合顺序的敏感性较低。因此，与游离酶相比，全细胞生物催化系统对底物可及性更敏感。此外，表征和分析表明，与HT + AS预处理相比，AS + HT/X预处理可以去除更多木质素，产生更易接近的表面，具有更大的外表面和更低的表面木质素覆盖率。因此，AS + HT/X预处理与基于纤维小体的全细胞糖化更兼容。
