Characterization of Microbial Decay and Microbial Communities in Waterlogged Archaeological Rosewood (<i>Dalbergia</i> Species)

Abstract

While numerous studies have examined microbial attacks on waterlogged archaeological wood, limited information is available regarding microbial attacks in waterlogged tropical hardwoods submerged in marine environments. In this context, we explored microbial attacks in waterlogged archaeological rosewood (Dalbergia species), a tropical hardwood species that was submerged in the Yellow Sea for approximately 700 years, using various microscopic techniques and next-generation sequencing (NGS) methods. Based on morphological features, Type-I soft rot decay was identified as the main decay type. Most fibers in waterlogged archaeological rosewood studied were gelatinous (G) fibers of tension wood and the mode of soft rot decay differed from fibers without the G-layer. Differences in decay resistance between vessel/axial parenchyma cells and fibers were not obvious. Vestured- and simple pit membranes showed higher decay resistance than vessel and axial parenchyma cell walls, respectively. Microbial community analysis by NGS revealed the dominance of Ascomycota and Basidiomycota in the fungal community. Various bacterial communities were also identified, although no prominent signs of bacterial decay were noted. The identified bacterial communities markedly differed from those reported previously in terms of their composition and abundance. Together, our results offer detailed insights into the microbial types and communities responsible for degrading waterlogged archaeological rosewood, contributing to a better understanding of microbial attacks in tropical hardwoods exposed to marine environments.

Keywords

• <i>Dalbergia</i> species
• tension wood
• gelatinous layer
• microbial community
• rosewood
• soft rot fungi