During the dilute acid pretreatment process, the resulting pseudo-lignin and lignin droplets deposited on the surface of lignocellulose and inhibit the enzymatic digestibility of cellulose in lignocellulose. However, how these lignins interact with cellulase enzymes and then affect enzymatic hydrolysis is still unknown. In this work, different fractions of surface lignin (SL) obtained from dilute acid-pretreated bamboo residues (DAP-BR) were extracted by various organic reagents and the residual lignin in extracted DAP-BR was obtained by the milled wood lignin (MWL) method. All of the lignin fractions obtained from DAP-BR were used to investigate the mechanism for interaction between lignin and cellulase using surface plasmon resonance (SPR) technology to understand how they affect enzymatic hydrolysis The results showed that removing surface lignin significantly decreased the yield for enzymatic hydrolysis DAP-BR from 36.5% to 18.6%. The addition of MWL samples to Avicel inhibited its enzymatic hydrolysis, while different SL samples showed slight increases in enzymatic digestibility. Due to the higher molecular weight and hydrophobicity of MWL samples versus SL samples, a stronger affinity for MWL (KD = 6.8–24.7 nM) was found versus that of SL (KD = 39.4–52.6 nM) by SPR analysis. The affinity constants of all tested lignins exhibited good correlations (r > 0.6) with the effects on enzymatic digestibility of extracted DAP-BR and Avicel. This work revealed that the surface lignin on DAP-BR is necessary for maintaining enzyme digestibility levels, and its removal has a negative impact on substrate digestibility.

中文翻译：

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了解酸预处理竹渣中不同残留木质素组分对其酶消化率的影响

在稀酸预处理过程中，产生的假木质素和木质素液滴沉积在木质纤维素表面，抑制了木质纤维素中纤维素的酶消化。然而，这些木质素如何与纤维素酶相互作用并进而影响酶水解仍是未知的。在这项工作中，从稀酸预处理的竹渣 (DAP-BR) 中获得的不同部分的表面木质素 (SL) 通过各种有机试剂进行提取，提取的 DAP-BR 中的残留木质素通过磨碎的木材木质素 (MWL) 获得方法。从 DAP-BR 中获得的所有木质素馏分都用于使用表面等离子共振 (SPR) 技术研究木质素和纤维素酶之间相互作用的机制，以了解它们如何影响酶促水解 结果表明，去除表面木质素会显着降低酶促反应的产率。水解 DAP-BR 从 36.5% 到 18.6%。向 Avicel 中添加 MWL 样品抑制了其酶水解，而不同的 SL 样品显示酶消化率略有增加。由于与 SL 样品相比，MWL 样品具有更高的分子量和疏水性，因此通过 SPR 分析发现对 MWL（KD = 6.8-24.7 nM）的亲和力比对 SL（KD = 39.4-52.6 nM）的亲和力更强。所有测试木质素的亲和常数都表现出良好的相关性（r > 0。6) 提取的 DAP-BR 和 Avicel 对酶消化率的影响。这项工作表明，DAP-BR 表面木质素是维持酶消化率水平所必需的，其去除对底物消化率有负面影响。