Characterization of Microbial Decay and Microbial Communities in Waterlogged Archaeological Wood Excavated from the Wetland

Abstract

Anatomical and chemical changes due to microbial decay and microbial communities in three waterlogged archaeological woods, namely Dongnim 1, Dongnim 2, and Dongnim 3, excavated from the wetland of the Dongnim-dong archaeological site in Gwangju, were investigated. Dongnim 1−3 exhibited a maximum moisture content approximately 6 to 8 times higher than that of undecayed recent wood, and there was no correlation with the burial period. Chemical analysis revealed an increase in ash and hot water extractive content in Dongnim 1−3 compared to undecayed recent wood, while the solvent extractive content tended to decrease. Additionally, there was a significant decrease in holocellulose content with a relative increase in lignin concentration in Dongnim 1−3. Microscopic observations showed erosion bacteria decay and soft rot decay in Dongnim 1−3. The microbial community analysis of Dongnim 2 and 3 revealed the dominance of Ascomycota (98% to 99%) in the fungal community and Proteobacteria (34% to 55%) as the predominant bacterial phylum. Nonetheless, significant differences in microbial community structure and diversity were observed between Dongnim 2 and Dongnim 3.