Inhibitory effects of lignin on enzymatic hydrolysis: The role of lignin chemistry and molecular weight
Inhibitory effects of lignin on enzymatic hydrolysis: The role of lignin chemistry and molecular weight
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DOI：
10.1016/j.renene.2018.02.079
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发表时间：
2018-08-01
期刊：
影响因子：
8.7
通讯作者：
Zheng, Yi
中科院分区：
文献类型：
--
作者：
Li, Xiang;Li, Mi;Zheng, Yi
木质纤维素是一种很有前途的生物燃料生产原料，而木质素对整个过程，特别是酶水解提出了巨大的挑战。在本研究中，不同类型的木质素通过不同的机制抑制酶水解。火炬松有机溶剂木质素吸附酶无效，减少了纤维素的可用酶，从而降低水解速率和最终糖产率。硫酸盐松木质素沉淀在纤维素表面，阻止纤维素与酶的接触。木质素的分子量影响其缓蚀效果。低分子量的木质素与酶的结合是无效的，随着分子量的增加，木质素沉积在纤维素上所产生的空间排斥作用变得更加明显。NMR分析揭示了木质素的结构特征，例如，官能团S/G比值决定了木质素在酶解过程中的行为。高含量的脂肪族羟基或低含量的羧基导致高的表面疏水性，增加了木质素与酶之间的吸附。此外，底物反应性也是影响酶解的重要因素。结晶度越高的纤维素水解速率越慢，转化率越低。当结晶度指数从0.43增加到0.72和0.81时，最终转化率分别从80下降到68%和57%。(C)2018爱思唯尔有限公司版权所有
lignocellulose is a promising feedstock for biofuel production, while lignin poses a grand challenge on the entire process, especially enzymatic hydrolysis. In this study, different types of lignin inhibited enzymatic hydrolysis by different mechanisms. Organosolv lignin from Loblolly pine adsorbed enzyme nonproductively and reduced the available enzyme for cellulose, therefore decreasing hydrolysis rate and ultimate sugar yield. Kraft pine lignin precipitated on the surface of cellulose, preventing it from contacting with enzyme. The molecular weight influenced the inhibition effect of lignin. Lignin of lower molecular weight could bind enzyme nonproductively and when the molecular weight increased, the steric repulsion caused by lignin deposition on cellulose became more significant. The NMR analysis revealed that lignin structural features, e.g., functional groups, S/G ratio, determined the behaviors of lignin in enzymatic hydrolysis. High content of aliphatic hydroxyl groups, or low content of carboxylic groups led to high surface hydrophobicity, increasing the adsorption between lignin and enzyme. In addition, the substrate reactivity is also an important factor that affects enzymatic hydrolysis. Cellulose with higher crystallinity exhibited slower hydrolysis rate and lower conversion. When the crystallinity index increased from 0.43 to 0.72 and 0.81, the ultimate conversion decreased from 80 to 68% and 57%, respectively. (C) 2018 Elsevier Ltd. All rights reserved.