Data_Sheet_1_Applicability of Recombinant Laccases From the White-Rot Fungus Obba rivulosa for Mediator-Promoted Oxidation of Biorefinery Lignin at Low pH.docx

Utilization of lignin-rich side streams has been a focus of intensive studies recently. Combining biocatalytic methods with chemical treatments is a promising approach for sustainable modification of lignocellulosic waste streams. Laccases are catalysts in lignin biodegradation with proven applicability in industrial scale. Laccases directly oxidize lignin phenolic components, and their functional range can be expanded using low-molecular-weight compounds as mediators to include non-phenolic lignin structures. In this work, we studied in detail recombinant laccases from the selectively lignin-degrading white-rot fungus Obba rivulosa for their properties and evaluated their potential as industrial biocatalysts for the modification of wood lignin and lignin-like compounds. We screened and optimized various laccase mediator systems (LMSs) using lignin model compounds and applied the optimized reaction conditions to biorefinery-sourced technical lignin. In the presence of both N–OH-type and phenolic mediators, the O. rivulosa laccases were shown to selectively oxidize lignin in acidic reaction conditions, where a cosolvent is needed to enhance lignin solubility. In comparison to catalytic iron(III)–(2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) oxidation systems, the syringyl-type lignin units were preferred in mediated biocatalytic oxidation systems.

富含木质素的副产物资源化利用，近年来已成为学界重点研究方向。将生物催化方法与化学处理手段相结合，是实现木质纤维素废料流可持续改性的极具前景的技术路径。漆酶（Laccases）是参与木质素生物降解的催化剂，已被证实可应用于工业规模化生产。漆酶可直接氧化木质素的酚类组分，通过添加低分子量化合物作为介体，能够拓展其催化底物范围，使其可作用于非酚类木质素结构。
本研究针对可选择性降解木质素的白腐真菌Obba rivulosa所产的重组漆酶开展了详细的性能表征，并评估了其作为工业生物催化剂，用于改性木材木质素及类木质素化合物的应用潜力。我们利用木质素模型化合物筛选并优化了多种漆酶介体系统（Laccase Mediator Systems, LMSs），并将优化后的反应条件应用于生物炼制来源的工业木质素。
在N-羟基型介体与酚类介体共同存在时，Obba rivulosa漆酶可在酸性反应条件下实现木质素的选择性氧化，该反应体系需添加助溶剂以提升木质素的溶解度。与催化型三价铁-(2,2,6,6-四甲基哌啶-1-基)氧自由基（TEMPO）氧化体系相比，介体型生物催化氧化体系更倾向于氧化丁香基型木质素单元。