Associations between fungal species and water-damaged building materials

Abstract

Fungal growth in damp or water-damaged buildings worldwide is an increasing problem, which has adverse effects on both the occupants and the buildings. Air sampling alone in moldy buildings does not reveal the full diversity of fungal species growing on building materials. One aim of this study was to estimate the qualitative and quantitative diversity of fungi growing on damp or water-damaged building materials. Another was to determine if associations exist between the most commonly found fungal species and different types of materials. More than 5,300 surface samples were taken by means of V8 contact plates from materials with visible fungal growth. Fungal identifications and information on building material components were analyzed using multivariate statistic methods to determine associations between fungi and material components. The results confirmed that Penicillium chrysogenum and Aspergillus versicolor are the most common fungal species in water-damaged buildings. The results also showed Chaetomium spp., Acremonium spp., and Ulocladium spp. to be very common on damp building materials. Analyses show that associated mycobiotas exist on different building materials. Associations were found between (i) Acremonium spp., Penicillium chrysogenum, Stachybotrys spp., Ulocladium spp., and gypsum and wallpaper, (ii) Arthrinium phaeospermum, Aureobasidium pullulans, Cladosporium herbarum, Trichoderma spp., yeasts, and different types of wood and plywood, and (iii) Aspergillus fumigatus, Aspergillus melleus, Aspergillus niger, Aspergillus ochraceus, Chaetomium spp., Mucor racemosus, Mucor spinosus, and concrete and other floor-related materials. These results can be used to develop new and resistant building materials and relevant allergen extracts and to help focus research on relevant mycotoxins, microbial volatile organic compounds (MVOCs), and microparticles released into the indoor environment.

Fig. 1.

Loadings plot from the principal component analysis (PCA) based on the qualitative matrix A [5,353 samples × (30 materials and 42 fungi)]. The plot shows associations between building materials and fungi (e.g., between wood and Alternaria tenuissima, Cladosporium herbarum, Rhodotorula mucilaginosa, and yeasts). Fungi and building materials encircled are particularly associated. Fungi or components close to the centroid have little or no association with each other, occur infrequently (<4%), and have little or no influence on the PCA model. Axes are principal components, PC 1 and PC 2, with loading values.

Fig. 2.

Biplot from the correspondence analysis (CA) based on the quantitative sum table B (matrix B [4,241 samples × (25 materials and 41 fungi)] summarized in a 41-by-25 table). The biplot shows the association between building material and fungal identity (e.g., between gypsum, glass fiber, and wallpaper and Ulocladium spp. and Stachybotrys spp.). The dotted lines show the distance of any fungus to the centroid, i.e., fungi farthest away from the centroid deviate the most from what would be expected based on the whole data table. Axes are correspondence components, DIM 1 and DIM 2, with score and loading values.