Fungal competition in thermally modified Scots pine wood as related to changes in lignocellulosic composition and laccase activity.

Lignocellulosic composition undergoes significant changes after thermal modification (TM), thus affecting the competitive environment for decaying fungi and ultimately the decay resistance of the thermally modified wood (TMW). In this study, dual-fungi culture outcomes of white-rot fungus Trametes versicolor (Tv) and brown-rot fungus Gloeophyllum trabeum (Gt) were investigated on both unmodified and thermally modified Scots pine (Pinus sylvestris) wood blocks and wood powder at two treatment temperatures (180 °C, 210 °C), and the relationship between lignocellulosic composition and fungal laccase activity was further discussed. Results revealed that dual-fungi culture significantly accelerated degradation of lignocellulosic components in unmodified wood, especially on cellulose; whereas for TMW at 210 °C, dual-fungi culture caused no additional degradation compared to mono-fungus culture. Dual fungi moderately increased laccase activity; however, this enhancement was not clearly reflected in the corresponding lignin degradation efficiency. The decay resistance of TMW can be primarily attributed to structural modification in lignin, increased relative cellulose crystallinity, and the reduction of monosaccharides derived from hemicellulose. These findings contribute to a better understanding of the effects of TM on fungal interactions and the enhanced decay resistance of TMW in practical applications, particularly from the perspective of dual-fungi culture.