Open Access

ARTICLE

Investigation of the Interaction Mechanism between Lignin Structural Units and Enzyme

Lijing Huang, Penghui Li, Kangjie Jiang, Wenjuan Wu^*

Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing, 210037, China

* Corresponding Author: Wenjuan Wu. Email:

(This article belongs to this Special Issue: Process and Engineering of Lignocellulose Utilization)

Journal of Renewable Materials 2023, 11(4), 1613-1626. https://doi.org/10.32604/jrm.2022.023605

Received 05 May 2022; Accepted 01 July 2022; Issue published 01 December 2022

Abstract

The effect of lignin structural units on enzymatic hydrolysis of lignocellulosic biomass was investigated, especially the inhibitory role of lignin in non-productive adsorption with enzymes. Milled wood lignin (MWL) was isolated from different hardwoods of poplar, eucalyptus and acacia. The isolated lignin samples were characterized by elemental analysis, gel permeation chromatography, nitrobenzene oxidation and fourier infrared spectroscopy. The mechanism of lignin structural units on enzymatic hydrolysis of cellulose was studied by quartz crystal microbalance (QCM). The results showed that different structural units of lignin had different adsorption capacity for enzymes. The results of nitrobenzene oxidation indicated that the S/G ratio (S: syringyl-like lignin structures; G: guaiacyl-like lignin structures) of lignin of poplar was 0.99, that of eucalyptus was 1.92 and that of acacia was 1.34. According to the results of QCM, the adsorption capacity of the three lignin films was as follows: Poplar MWL (S/G ratio 0.99) < Acacia MWL (S/G ratio 1.34) < Eucalyptus MWL (S/G ratio 1.92). Eucalyptus MWL with higher degree of condensation and S/G ratio showed stronger affinity to enzymes and more non-productive adsorption with enzymes, resulting in less adsorption between enzymes and cellulose, and lower enzymatic hydrolysis efficiency.

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