Guaiacol-enhanced laccase secretion by <i>Trametes versicolor</i> for lignin modification toward high-performance bamboo composites

Abstract

This study reports high-performance bamboo-based composites engineered through a biological eco-modification strategy involving targeted lignin depolymerisation. By leveraging guaiacol-enhanced <i>Trametes versicolor</i> pretreatment, we achieved substantial improvements in the mechanical properties and water resistance of bamboo-phenolic resin composites via efficient biological modification of Dendrocalamus sinicus. This targeted biological modification boosted laccase activity to 2566.28 U/L, selectively depolymerised lignin and hemicellulose (by 6.97% and 11.46%, respectively) while preserving the cell wall skeleton, increased the crystallinity of bamboo from 28.28% to 31.94%, and enhanced the surface reactivity of bamboo for subsequent resin bonding. This bioconversion enhanced bamboo's chemical reactivity via targeted lignin demethoxylation and β-O-4 bond cleavage, efficiently generating additional phenolic hydroxyl groups, while also improving surface wettability (contact angle reduced from 109.73° to 79.96°) to facilitate resin penetration. Consequently, the resulting composites exhibited superior fiber-resin interfacial bonding, leading to exceptional mechanical performance, with tensile strength reaching 286.65 MPa (40.2% higher than untreated controls) and bonding strength of 9.74 MPa (33.6% improvement). Furthermore, the composites demonstrated enhanced water resistance and interfacial stability, underscoring their suitability for load-bearing applications. This targeted lignin depolymerisation strategy directly optimises the bamboo-resin interface, offering a sustainable pathway for the industrial production of high-strength biocomposites and enabling the value-added utilisation of bamboo resources.