Air and wall mycobiota interactions—A case study in the Old Cathedral of Coimbra

Abstract

The microbiota present in public buildings - fungal, algae and fungi that thrive in buildings and in their construction materials - influence the structural condition as well as, potentially, the health of those who live, work, or visit them. These organisms can colonise and deteriorate all kinds of construction materials such as stone, wood, bricks, glass, steal and metals, concrete, ceramics, tiles, among others. One of the vehicles that helps to spread and therefore contributes to this biological contamination is the air and its microbiome in such environments. In this work we analysed the fungal air burden existing in the cloister of the Old Cathedral of Coimbra, in four chapels and the central square of this cloister, in two differentseasons. This allowed relating the fungal air burden with the established fungal communities (mycobiota) that were present in biodeteriorated spots on the walls of the studied chapels, in the context of a previous work from our research team. The fungal air burden was higher in the summer, although with lower diversity. Patterns of distribution varied between sites, but in general, the most abundant species were found present in both the central square and chapels, suggesting that the air flows between these places are likely to vector the exchange of fungal propagules. Moreover, some less frequent species were found specific to particular chapels, and were not found in the air samples from the central square. These findings support the idea of the specificity and environmental requirements of most retrieved isolates, while showing that the chapels have the potential to host a large set of organisms that are not present elsewhere. Many of these fungi are linked to biodeterioration phenomena of the walls and/or are associated to pathogenic and toxigenic effects in humans. This study highlights the relevance of assessing the microbiota that thrive in such settings, and how the design and architecture can influence the composition of the established microbiota.