Objective Research on brown-rot fungi decay mechanisms has primarily focused on the degradation of wood cell wall components. However, the influence of wood’s physical and chemical properties on initial decay process remains unclear. This study aims to investigate the impact of wood structural characteristics on initial brown-rot mechanism, thereby deepening the understanding of brown-rot fungi decay mechanisms and providing scientific guidance for wood preservation and efficient biomass utilization.

Method Pinus sylvestris was used as the research subject. Ethanol extraction (EE), ethanol-sodium chlorite treatment (EE-SC) and hydrothermal treatment (HT) were employed to prepare wood specimens with low extractives, low lignin, and low hemicellulose content, respectively. The brown-rot fungus Gloeophyllum trabeum was selected for decay testing. SEM, FTIR, and XRD characterization techniques were used to study the appearance, fungal mycelial growth, mass loss rate, and changes in main components (cellulose, hemicellulose, and lignin) of P. sylvestris specimens at different decay stages. The initial brown-rot degradation mechanisms of wood specimens with different structural characteristics were thoroughly analyzed.

Result Wood specimens with low extractives, low lignin, and low hemicellulose content were successfully prepared by ethanol extraction, ethanol-sodium chlorite treatment, and hydrothermal treatment. Mass loss rate, macro- and micro-structural analysis, and chemical composition results indicated that all treated wood specimens underwent degradation during the brown-rot test. The degradation degree of low-extractive wood specimens was similar to control, while the mycelial growth and cell wall degradation of low-lignin and low-hemicellulose wood specimens were significantly higher than those control. After 15 days of brown-rot, the relative content of hemicellulose increased in all treated specimens. This indicated that hemicellulose was relatively more preserved than other components at this stage. It is therefore inferred that hemicellulose may not be the optimal carbon source for brown-rot fungi. The degradation of hemicellulose primarily serves to disrupt the integrity of cell wall structure.

Conclusion Removal of extractives has no significant impact on the initial decay rate of wood, while selective removal of lignin or hemicellulose can significantly accelerate the initial brown-rot degradation process. At the initial stage of wood decay by brown-rot fungi, the degradation of hemicellulose disrupts the structural barrier of cell wall, providing a pathway for cellulose degradation. This reveals the strategy of brown-rot fungi in utilizing wood resources and offers new insights into understanding the decay mechanisms. This study, from the new perspective of correlation between wood structure and degradation response, deeply analyzes the wood decay mechanism. It also provides a theoretical basis for the development of green wood protection technologies based on cell wall-targeted regulation and the efficient conversion of biomass resources.