Chemical composition of material extractives influences microbial growth and dynamics on wetted wood materials

Abstract

The impact of material chemical composition on microbial growth on building materials remains relatively poorly understood. We investigate the influence of the chemical composition of material extractives on microbial growth and community dynamics on 30 different wood species that were naturally inoculated, wetted, and held at high humidity for several weeks. Microbial growth was assessed by visual assessment and molecular sequencing. Unwetted material powders and microbial swab samples were analyzed using reverse phase liquid chromatography with tandem mass spectrometry. Different wood species demonstrated varying susceptibility to microbial growth after 3 weeks and visible coverage and fungal qPCR concentrations were correlated (R 2 = 0.55). Aspergillaceae was most abundant across all samples; Meruliaceae was more prevalent on 8 materials with the highest visible microbial growth. A larger and more diverse set of compounds was detected from the wood shavings compared to the microbial swabs, indicating a complex and heterogeneous chemical composition within wood types. Several individual compounds putatively identified in wood samples showed statistically significant, near-monotonic associations with microbial growth, including C 11 H 16 o 4 , c 18 H 34 o 4 , and c 6 H 15 NO. A pilot experiment confirmed the inhibitory effects of dosing a sample of wood materials with varying concentrations of liquid C 6 H 15 NO (assuming it presented as Diethylethanolamine). Buildings are complex ecosystems that contain many habitats for microbial communities 1-4. In buildings that lack a history of water damage or exposure to excessive moisture conditions, microbial communities found on surfaces are generally considered to consist of deposited microbes originating from outdoor environments and the microbiome of human occupants, typically with minimal microbial growth 5,6. However, most buildings experience some kind of high moisture event(s) throughout their life cycles, often resulting from rain or snow penetration, plumbing leaks, building foundation cracks, floods and extreme weather events, condensation of damp air, and/or rising dampness from the ground 7-9. Building materials that have experienced moisture damage and/or are subjected to sustained high (i.e., > 80%) relative humidity (RH) can experience microbial growth 9 , which can generate metabolites that are toxic to humans 10,11. Microbial growth can also cause material biodeterioration, which adversely affects their physical and mechanical properties 12. Moreover, dampness in buildings alone is associated with a variety of adverse health outcomes 13-16. There are several well-known factors that influence the likelihood and extent of microbial growth on building materials, including environmental conditions, water availability, and material susceptibility to microbial growth.

The molecular impact of life in an indoor environment

“…The datasets that were co-networked are food [FoodOmics ( 8 ); overlap, ~15.7%], human microbes [Human Microbiome Project ( 24 ); overlap, ~1.1%], and feces [American Gut ( 25 ); overlap, ~8.6%; feces contain both food and microbial molecules ( 25 )]. Overlap with bacterial and fungal growth on wetted wood ( 26 ) was ~2.6% and on common building materials in humid conditions ( 27 ) was ~4.7%.…”

Quantification of microbial growth pattern on growth medium using image processing program and evaluation of antifungal activities of wood vinegar

“…The conditions and primary information for each available fungal strain that showed more than 50% inhibition efficiency and 100% inhibition efficiency, depending on the concentration of wood vinegar added. The standard deviation of ImageJ was lower than the macroscopic method used in other studies (Theapparat et al 2015;Zhao et al 2020).…”

Sustainability in Wood Products: A New Perspective for Handling Natural Diversity

“…Their composition and concentration strongly depends on the wood species and anatomy but can be divided into three major subgroups: (i) phenolic compounds (subdivided in lignans, stilbenes, flavonoids, and tannins), (ii) aliphatic compounds, and (iii) terpenes and terpenoids. Aliphatic compounds (fats and waxes) can act as surfactants limiting fungal adhesion on wood surface, while phenolics can have a direct antifungal effect . Due to their vast chemical and structural variability, extractives are an important cause of wood inhomogeneity in processing and wood products because they can influence wood color, swelling, and shrinkage, durability, bonding, and coating behavior. , What is seen as a clear disadvantage from the point of view of conventional wood processing, however, can be turned into a source of bioinspiration for developing more sustainable wood treatments, such as preservatives and pest repellents, and for conferring increased fire resistance.…”