Lin Wenqian, Yang Jinlai, Zheng Yayue, Huang Caoxing, Yong Qiang
Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, China.
China National Bamboo Research Center and Key Laboratory of High Efficient Processing of Bamboo of Zhejiang Province, Hangzhou, 310012, Zhejiang, China.
Biotechnol Biofuels. 2021 Jun 23;14(1):143. doi: 10.1186/s13068-021-01994-y.
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 RESULTS: 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.
在稀酸预处理过程中，生成的伪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解消化率。然而，这些木质素如何与纤维素酶相互作用进而影响酶水解仍不清楚。在本研究中，通过各种有机试剂提取了稀酸预处理竹渣（DAP - BR）中不同级分的表面木质素（SL），并采用磨木木素（MWL）法获得了提取后的DAP - BR中的残留木质素。利用表面等离子体共振（SPR）技术，将从DAP - BR中获得的所有木质素级分用于研究木质素与纤维素酶之间的相互作用机制，以了解它们如何影响酶水解。结果：结果表明，去除表面木质素显著降低了DAP - BR的酶水解产率，从36.5%降至18.6%。向微晶纤维素中添加MWL样品会抑制其酶水解，而不同的SL样品则显示酶消化率略有增加。由于MWL样品相对于SL样品具有更高的分子量和疏水性，通过SPR分析发现MWL（KD = 6.8 - 24.7 nM）比SL（KD = 39.4 - 52.6 nM）具有更强的亲和力。所有测试木质素的亲和常数与对提取的DAP - BR和微晶纤维素的酶消化率的影响均呈现良好的相关性（r > 0.6）。
本研究表明，DAP - BR上的表面木质素对于维持酶消化率水平是必要的，去除它会对底物消化率产生负面影响。
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