In this study, lignin from acid-catalyzed glycerol (AG) pretreatment of sugarcane bagasse was recovered and characterized. Its effects on enzymatic hydrolysis and cellulase recycling were then investigated. Prior to lignin recovery, a two-step dilute acid and AG pretreatment was used to deconstruct sugarcane bagasse, which led to a glucan enzymatic digestibility of 99%, a glucose yield of 91%, and a xylose yield of 67%. Following enzymatic hydrolysis, lignin-rich residues were recovered by simple filtration at a lignin yield of 63% and a lignin purity of 90%. Two-dimensional heteronuclear single quantum correlation nuclear magnetic resonance analysis showed that glycerol had modified the bagasse lignin through α-etherification of β-aryl ethers and γ-esterification of hydroxycinnamic acids, generating a novel lignin structure. ³¹P NMR analysis showed that the recovered lignin had a high number of aliphatic hydroxyl groups suggesting that it is highly hydrophilic in nature. As a result, the AG lignin did not inhibit enzymatic hydrolysis of pretreated bagasse, and cellulases adsorbed onto lignin-rich solid residues were successfully recycled three times, leading to an average glucan digestibility of 93% (for a total of four batches) at an average cellulase dosage of only 4.1 FPU/g glucan. This study provides new and important information on AG pretreatment, which is critical toward the development of biorefinery processes based on this pretreatment.

中文翻译：

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酸催化甘油对甘蔗渣的预处理：了解木质素的性质及其对酶水解的影响

在这项研究中，从甘蔗渣的酸催化甘油（AG）预处理中回收木质素并进行了表征。然后研究了其对酶促水解和纤维素酶回收的影响。在回收木质素之前，使用两步稀酸和AG预处理对甘蔗渣进行解构，从而使葡聚糖的酶消化率达到99％，葡萄糖得率达到91％，木糖得率达到67％。酶促水解后，通过简单过滤以63％的木质素收率和90％的木质素纯度回收富含木质素的残留物。二维异核单量子相关核磁共振分析表明，甘油通过β-芳基醚的α-醚化和羟基肉桂酸的γ-酯化修饰了甘蔗渣木质素，产生了新的木质素结构。³¹ P NMR分析表明，回收的木质素具有大量的脂肪族羟基，表明其本质上是高度亲水的。结果，AG木质素没有抑制预处理的蔗渣的酶水解，并且吸附在富含木质素的固体残留物上的纤维素酶成功地循环了三次，因此平均一次的葡聚糖消化率为93％（总共四个批次）。平均纤维素酶用量仅为4.1 FPU / g葡聚糖。这项研究提供了有关AG预处理的新的重要信息，这对于基于该预处理开发生物精炼工艺至关重要。