Growth optimization and dual cellulolytic degradation pathways in Serpula lacrymans.

Serpula lacrymans is the most destructive brown-rot fungus affecting timber in temperate regions, causing severe economic losses in construction and cultural heritage. Conventional chemical treatments are largely ineffective, as they act only on wood surfaces and fail to eradicate fungal growth within deeper layers. Previous studies have described the cellulolytic activity of S. lacrymans as weak and strictly substrate-inducible, despite genomic evidence for GH12-type endoglucanases. Moreover, cultivation in traditional malt- or CMC-based media often yields insufficient biomass, limiting reproducibility of biochemical assays and obscuring the true enzymatic spectrum. Here, we report that cultivation in Murashige-Skoog salt medium supplemented with sucrose markedly improves biomass yield and metabolite accumulation, enabling reliable physiological and enzymatic analyses. Our findings reveal basal endoglucanase activity and demonstrate that S. lacrymans employs both hydrolytic and Fenton-like oxidative mechanisms in cellulose degradation. These insights advance the understanding of its decay system and provide a foundation for developing biological control strategies against this highly destructive fungus.