Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, China; College of Light Industry and Food Engineering, Nanjing Forestry University, 159 Longpan Road, Nanjing 210037, China.
Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, China; College of Light Industry and Food Engineering, Nanjing Forestry University, 159 Longpan Road, Nanjing 210037, China.
Int J Biol Macromol. 2023 Feb 1;227:664-672. doi: 10.1016/j.ijbiomac.2022.12.054. Epub 2022 Dec 13.
Most studies about the influence of lignin on enzymatic digestibility of lignocellulose have focused on the content and properties, but less on the detaching behavior of lignin. The samples were prepared from Pinus massoniana wood chips by kraft cooking followed by delignification using oxygen/alkali (KP-O) and chlorine dioxide (KP-D), respectively. Two oxidative delignified samples with a similar lignin content were subject to enzymatic hydrolysis at both pH of 5.0 and 5.5 to investigate the effects of lignin detached rate (LDR) on substrate enzymatic digestibility (SED). The LDRs and the SEDs from both samples increased with the enzymatic hydrolysis time, and the situations of KP-D were much higher than those of KP-O under the same enzymatic hydrolysis time. The results of enzymatic hydrolysis at an elevated pH of 5.5 and the changes in concentration of free cellulase of the two samples indicated that the lignin detaching increased the free cellulase concentration, and thus promoted the enzymatic digestibility. Moreover, lignin distribution analysis by X-ray photoelectric spectroscopy and confocal laser scanning microscopy indicated surface lignin being preferentially detached. This work provided a reference for rationally designing pretreatment strategies, which can improve the efficiency of enzyme hydrolysis of lignocellulosic biomass.
大多数关于木质素对木质纤维素酶解可及性影响的研究都集中在木质素的含量和性质上，而对木质素的脱落行为关注较少。该样品由马尾松木片经硫酸盐法蒸煮后，分别采用氧/碱（KP-O）和二氧化氯（KP-D）脱木质素制得。对两个木质素脱除率（LDR）相近的氧化脱木质素样品进行了在 pH 值为 5.0 和 5.5 下的酶水解实验，以研究木质素脱落率对底物酶解可及性（SED）的影响。在相同的酶水解时间内，两种样品的 LDR 和 SED 均随酶水解时间的增加而增加，而 KP-D 样品的情况远高于 KP-O 样品。在 pH 值为 5.5 的升高的 pH 值下的酶水解结果和两种样品中游离纤维素酶浓度的变化表明，木质素的脱落增加了游离纤维素酶的浓度，从而促进了酶解。此外，X 射线光电光谱和共焦激光扫描显微镜的木质素分布分析表明，表面木质素优先脱落。这项工作为合理设计预处理策略提供了参考，这可以提高木质纤维素生物质酶水解的效率。
