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).

Despite considerable efforts to characterize the microbial ecology of the built environment, the metabolic mechanisms underpinning microbial colonization and successional dynamics remain unclear, particularly at high moisture conditions. Here, we applied bacterial/viral particle counting, qPCR, amplicon sequencing of the genes encoding 16S and ITS rRNA, and metabolomics to longitudinally characterize the ecological dynamics of four common building materials maintained at high humidity. We varied the natural inoculum provided to each material and wet half of the samples to simulate a potable water leak. Wetted materials had higher growth rates and lower alpha diversity compared to non-wetted materials, and wetting described the majority of the variance in bacterial, fungal, and metabolite structure. Inoculation location was weakly associated with bacterial and fungal beta diversity. Material type influenced bacterial and viral particle abundance and bacterial and metabolic (but not fungal) diversity. Metabolites indicative of microbial activity were identified, and they too differed by material.

Elevated N-linked glycosylation of IgG V regions (IgG-V^N-Glyc) is an emerging molecular phenotype associated with autoimmune disorders. To test the broader specificity of elevated IgG-V^N-Glyc, we studied patients with distinct subtypes of myasthenia gravis (MG), a B cell-mediated autoimmune disease. Our experimental design focused on examining the B cell repertoire and total IgG. It specifically included adaptive immune receptor repertoire sequencing to quantify and characterize N-linked glycosylation sites in the circulating BCR repertoire, proteomics to examine glycosylation patterns of the total circulating IgG, and an exploration of human-derived recombinant autoantibodies, which were studied with mass spectrometry and Ag binding assays to respectively confirm occupation of glycosylation sites and determine whether they alter binding. We found that the frequency of IgG-V^N-Glyc motifs was increased in the total BCR repertoire of patients with MG when compared with healthy donors. The elevated frequency was attributed to both biased V gene segment usage and somatic hypermutation. IgG-V^N-Glyc could be observed in the total circulating IgG in a subset of patients with MG. Autoantigen binding, by four patient-derived MG autoantigen-specific mAbs with experimentally confirmed presence of IgG-V^N-Glyc, was not altered by the glycosylation. Our findings extend prior work on patterns of Ig V region N-linked glycosylation in autoimmunity to MG subtypes.