Mechanisms of manganese-modified biochar and white-rot fungi in enhancing compost humification: Boosting polyphenol pathway by lignocellulose degradation

초록

Lignocellulose-rich biomass is a wide and abundant carbon source in nature, and its conversion into humus (HS) through composting technology is a promising pathway for resource utilization. However, the difficult degradation characteristics of lignocellulose have become an important bottleneck limiting the humification efficiency of composting. This study aimed to enhance lignocellulose degradation and HS formation by inoculating P. chrysosporium with manganese-modified biochar (MBC) addition while exploring the underlying mechanisms. Results showed that lignin degradation increased by 239.00%, with humic acid (HA) content and the HA/fulvic acid (FA) ratio rising by 36.83% and 72.33%, respectively, in the treatment of inoculation with P.chrysosporium and MBC addition (T3) compared to CK. Spectroscopic analysis revealed strengthened polyphenol and Maillard humification pathways, with the polyphenol pathway being the main mechanism for HS formation. T3 exhibited enhanced microbial synergism and network complexity, enriched lignocellulose-degrading microorganisms (Firmicutes, Actinobacteria, Proteobacteria, Ascomycota, and Basidiomycota), up-regulated CAZyme genes (AAs and GHs), and significantly increased activities of lignin peroxidase, manganese peroxidase, and laccase, contributing to lignocellulose degradation. Meanwhile, enhanced carbohydrate and amino acid metabolism produced metabolites such as phenolic and aromatic amino acid compounds, providing more precursors for the polyphenol pathway and promoting HS formation. The microbial-mediated Mn redox reaction increased the & sdot;OH content in T3 by 32.00%-112.30%, which could create more binding sites for functional enzymes to degrade lignocellulose. Mn acts as a redox mediator and catalyst, which accelerates lignocellulose degradation and precursor condensation reactions to promote HA formation. This study presents an effective strategy to improve the humification efficiency in lignocellulose-rich biomass.

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