Filamentous fungi in Brazilian indoor cultural heritage as potential risk to human health and biodeterioration of artworks

Nossa Senhora da Assuncao Cathedral is located in Mariana, the first capital of the state of Minas Gerais, Brazil, and the first seat of the bishopric. Owing to this heritage, the Cathedral has an artistic collection composed of altarpieces with execution attributed to the renowned artists in the eighteenth-century Brazil. These are unique relics that build the religious, artistic, and social culture of the Brazilian city, listed as National Heritage (NH) by the National Institute of Historic and Artistic Heritage (IPHAN). It is, therefore, crucial to preserve these artworks and ensure proper health of the restorers. The assessment of air quality is a vital microbiological parameter to ensure the health of the visitors of the Brazilian Cathedral and to preserve this building of historical relevance. The isolation and identification of cultivable fungal species in the indoor air are essential for treatment against microbial growth to avoid the biodeterioration of the artworks and to prevent possible human infections. Fifteen distinct taxa were identified, and three fungal species of clinical relevance were detected inside the Cathedral: Aspergillus fumigatus, Aspergillus flavus, and Trichophyton rubrum. The values obtained with regard to colony-forming unit (CFU) count, in the air inside the Cathedral, are in accordance with the Brazilian legislation and the World Health Organization (WHO). Majority species of filamentous fungi exhibited potential deterioration risks as producers of extracellular enzymes, acids, and pigments, such as Purpureocillum lilacinum, which presented proteolytic activity and the lowest pH value, and Stachybotrys chartarum, which showed high ICMC values and pigment production. In addition, these fungi populations obtained include pathogenic fungi, with the potential infection in humans, particularly systemic, cutaneous, and opportunistic mycoses. Therefore, appropriate measures for human health, such as the use of appropriate masks by conservators and restorers, are necessary to avoid mild and severe fungal infections.