Issue 5, 2020

Understanding laccase/HBT-catalyzed grass delignification at the molecular level


Laccase-mediator systems (LMS) are potential green tools to improve the valorization of lignocellulosic biomass by selective degradation of lignin. Despite extensive attention devoted to lignin degradation by LMS in literature, knowledge on the underlying mechanisms is largely limited to model compound studies. Here, we report a mechanistic study on the delignification of wheat straw (WS) and corn stover (CS) by a laccase/HBT system. Quantitative 13C-IS py-GC-MS analysis revealed that WS and CS were delignified in the range of 28–51% (w/w). Based on a combination of py-GC-MS, 2D NMR, SEC and RP-UHPLC-MS, extensive structural characterization of both residual and solubilized lignin structures was performed, from which we reconstructed the degradation pathway of native lignin by laccase/HBT. For the first time, we show that degradation of native lignin in the plant cell wall matrix by LMS occurs via both Cα–Cβ cleavage and ether cleavage of β-O-4′ aryl ethers, and that the latter primarily occurs via cleavage of the β-O bond. Cγ-Coumaroylated substructures were found to be more recalcitrant towards degradation than non-acylated substructures. In addition to lignin degradation, our results provide evidence for grafting of HBT onto lignin.

Graphical abstract: Understanding laccase/HBT-catalyzed grass delignification at the molecular level

Supplementary files

Article information

Article type
20 Dec 2019
13 Feb 2020
First published
13 Feb 2020
This article is Open Access
Creative Commons BY license

Green Chem., 2020,22, 1735-1746

Understanding laccase/HBT-catalyzed grass delignification at the molecular level

R. Hilgers, G. van Erven, V. Boerkamp, I. Sulaeva, A. Potthast, M. A. Kabel and J. Vincken, Green Chem., 2020, 22, 1735 DOI: 10.1039/C9GC04341A

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