Tang Chaojun, Gandla Madhavi Latha, Jönsson Leif J
Department of Chemistry, Umeå University, Umeå, Sweden.
Front Bioeng Biotechnol. 2022 Dec 13;10:1071159. doi: 10.3389/fbioe.2022.1071159. eCollection 2022.
The role of lignin in enzymatic saccharification of cellulose involving lytic polysaccharide monooxygenase (LPMO) was investigated in experiments with the solid and liquid fractions of pretreated Norway spruce from a biorefinery demonstration plant using hydrothermal pretreatment and impregnation with sulfur dioxide. Pretreated biomass before and after enzymatic saccharification was characterized using HPAEC, HPLC, -GC/MS, 2D-HSQC NMR, FTIR, and SEM. Chemical characterization indicated that relatively harsh pretreatment conditions resulted in that the solid phase contained no or very little hemicellulose but considerable amounts of pseudo-lignin, and that the liquid phase contained a relatively high concentration (∼5 g/L) of lignin-derived phenolics. As judged from reactions continuously supplied with either air or nitrogen gas, lignin and lignin fragments from both the solid and the liquid phases efficiently served as reductants in LPMO-supported saccharification. When air was used to promote LPMO activity, the enzymatic conversion of cellulose after 72 h was 25% higher in reactions with pretreated solids and buffer, and 14% higher in reactions with pretreatment liquid and microcrystalline cellulose. Research in this area is useful for designing efficient saccharification steps in biochemical conversion of lignocellulosic biomass.
在使用水热预处理和二氧化硫浸渍法对一家生物精炼示范厂的挪威云杉进行预处理后，对其固体和液体部分进行了实验，研究了木质素在涉及裂解多糖单加氧酶（LPMO）的纤维素酶促糖化中的作用。使用高效阴离子交换色谱（HPAEC）、高效液相色谱（HPLC）、气相色谱/质谱联用仪（GC/MS）、二维异核单量子相干核磁共振（2D-HSQC NMR）、傅里叶变换红外光谱（FTIR）和扫描电子显微镜（SEM）对酶促糖化前后的预处理生物质进行了表征。化学表征表明，相对苛刻的预处理条件导致固相不含或仅含极少量半纤维素，但含有大量假木质素，且液相含有相对较高浓度（约5 g/L）的木质素衍生酚类物质。从连续供应空气或氮气的反应判断，固相和液相中的木质素及木质素片段在LPMO辅助糖化中均有效地充当了还原剂。当使用空气促进LPMO活性时，在与预处理固体和缓冲液的反应中，72小时后纤维素的酶促转化率高出25%，在与预处理液体和微晶纤维素的反应中高出14%。该领域的研究对于设计木质纤维素生物质生化转化中的高效糖化步骤很有用。
