Characterization of Microbial Decay and Microbial Communities in Waterlogged Archaeological Rosewood (Dalbergia 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.

The Pivotal Role of Microscopy in Unravelling the Nature of Microbial Deterioration of Waterlogged Wood: A Review

“…With respect to relevance to the longevity of ancient waterlogged woods, the contribution of tension wood is expected to be insignificant, as the presence of a G-layer is considered to render tension wood fibres more susceptible to wood-destroying fungi than normal wood fibres [13]. However, in a recent study of the microbial decay in waterlogged archaeological rosewood, Kim et al [31] found the G-layer in tension wood fibres to show some resistance in the initial stages of attack by soft-rot fungi. From a biotechnological perspective, the unique features of tension wood fibres, particularly the presence of the cellulose-rich G-layer, are being exploited in developing processes to enhance bioethanol production from woody biomass rich in tension wood.…”

“…For waterlogged woods, recent microscopic studies have provided evidence of cell wall degradation by cavity-producing soft-rot fungi (Type I), tunnelling bacteria, and erosion bacteria, or predominantly by erosion bacteria [6,9,[15][16][17]27,[29][30][31]. Cell wall erosion-type attacks by soft-rot fungi (Type II) were rarely observed in such woods [31].…”

“…For waterlogged woods, recent microscopic studies have provided evidence of cell wall degradation by cavity-producing soft-rot fungi (Type I), tunnelling bacteria, and erosion bacteria, or predominantly by erosion bacteria [6,9,[15][16][17]27,[29][30][31]. Cell wall erosion-type attacks by soft-rot fungi (Type II) were rarely observed in such woods [31]. Attacks by soft-rot and tunnelling bacteria are present in waterlogged wood exposed to oxygenated environments, such as intertidal zones [9,30,32], which suggests that these organisms require oxygen for their activity.…”

High-Bond-Strength, Water-Resistant Magnesium Oxychloride Cement-Based Inorganic Adhesive Inspired by Adsorbed Heavy Metal Ions

“…Their excellent compressive strength provides them with outstanding internal bonding strength when used as adhesives, and the rod-like 5-phase crystals formed during hydration can be well anchored to the porous surface of wood, using the vessel channels and pits as the potential anchor points for the 5-phase crystals. 8,9 Therefore, MOC composites have natural advantages as wood adhesives.…”

“…Currently, aldehyde-containing adhesives still occupy the main position in the wood adhesives industry. , Formaldehyde-containing adhesives inevitably release harmful gases such as formaldehyde during production and use, which threatens the balance of the ecological environment and endangers human health. − Inorganic adhesives work over a wider temperature range and do not release volatile organic compounds during use, making them more environmentally friendly. , Magnesium oxychloride cement (MOC) composites are a new type of inorganic cementitious material that do not release harmful gases during preparation and use. Their excellent compressive strength provides them with outstanding internal bonding strength when used as adhesives, and the rod-like 5-phase crystals formed during hydration can be well anchored to the porous surface of wood, using the vessel channels and pits as the potential anchor points for the 5-phase crystals. , Therefore, MOC composites have natural advantages as wood adhesives.…”