Isolation, Identification of Serpula himantioides from Dingtao M2 Tomb and Its Wood Degradation Characteristics.

The Dingtao M2 Tomb, the largest, highest-specification, and best-preserved "Huangchangticou" tomb currently discovered in China, is of great significance for cultural relic conservation. During its dismantling and protection, extensive white filamentous fungal contamination was observed on the surface of sand-buried wood components. To clarify the dominant fungal species and its impact on wood cultural relics, the dominant fungus was isolated and purified from contaminated wood samples, and identified as Serpula himantioides (designated as DTW) via molecular and morphological methods. Systematic studies were conducted on DTW's wood degradation capacity, cellulase activities, regulatory effects of Fe3+ and Ca2+ on cellulase activities, whole-genome characteristics, and sensitivity to fungistatic agents. The results indicated that DTW exhibited strong wood degradation ability: after 60 days of inoculation, the maximum force, elongation at break, and tensile strength of wood chips decreased significantly, by 88.0%, 54.6%, and 88.6%, respectively, compared with the control group. The cultural relic microenvironment colonized by strain DTW is rich in Fe3+ and Ca2+. Both ions can significantly suppress the activity and specific activity of cellulase from strain DTW at elevated concentrations. Whole-genome sequencing revealed that DTW had a genome size of 68,519,434 bp with a Guanine-Cytosine (GC) content of 44.01% and 18,373 genes; Carbohydrate-Active Enzyme (CAZy) and Cell Wall-Degrading Enzyme (CWDE) database annotations confirmed its strong plant cell wall degradation ability. Additionally, DTW was sensitive to screened green fungistatic agents, which effectively inhibited its growth. This study clarifies the species and wood degradation mechanism of the dominant fungus on Dingtao M2 Tomb's sand-buried wood, providing theoretical and technical support for the protection of the tomb's wood cultural relics.