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 (R2 = 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 C11H16O4, C18H34O4, and C6H15NO. A pilot experiment confirmed the inhibitory effects of dosing a sample of wood materials with varying concentrations of liquid C6H15NO (assuming it presented as Diethylethanolamine).
Highlights
The impact of material chemical composition on microbial growth on building materials remains relatively poorly understood
Visible microbial growth was observed within 3 weeks on 13 of the 30 wood species, with different wood species demonstrating widely varying susceptibility to growth (Fig. 1)
Of the 13 species with the greatest visible coverage area, Beech (Fagus grandifolia) showed the greatest amount of coverage followed by Ponderosa Pine (Pinus ponderosa) and Basswood (Tilia americana)
Summary
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. Building materials that have experienced moisture damage and/or are subjected to sustained high (i.e., > 80%) relative humidity (RH) can experience microbial g rowth[9], which can generate metabolites that are toxic to humans[10,11]. Past research has shown that material composition appears to be a key driver of microbial growth susceptibility Materials such as ceiling tiles, wood, and gypsum board paper backing, which are organic or are produced from organic products, have been shown to provide ample nutrients to support fungal growth when held at high moisture conditions, while paper-free materials such as inorganic ceiling tiles and gypsum itself support little or no growth[28]. The composition of extractives in wood varies widely from species to species and can vary depending on geographical origin and from which part of the tree a sample o riginates[34,35,36]
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