Filamentous fungi associated with Brazilian stone samples: structure of the fungal community, diversity indexes, and ecological analysis

Evaluation of microbiological air parameters and the fungal community involved in the potential risks of biodeterioration in a cultural heritage of humanity, Ouro Preto, Brazil

The research of the microbiological air quality of a building considered a human historical and cultural heritage site by the United Nations Educational, Scientific, and Cultural Organization is fundamental for preventive conservation action, mainly because it identifies cultivable fungal species around the collections and suggests the appropriate treatment choice. This study investigated the air microbiological parameters inside the Nossa Senhora da Conceição Church and identified the population of airborne fungi. Sixty filamentous fungal isolates were detected with ten distinct taxa. The counts of colony forming units (CFUs) performed at 10 different points were in accordance with Brazilian legislation. In addition, the presence of two fungal species was detected colonizing artworks covered with gold leaves: Cladosporium cladosporioides and Aspergillus versicolor. Air quality monitoring inside the church was in accordance with the required Brazilian legislation standards. The composition of the filamentous fungal community included the presence of human fungal pathogens; for this reason, the use of personal protective equipment was recommended during the restoration work. Thus, characterization of the air microbiological parameters helps to preserve not only the building's collection, but also the health of the faithful, conservators-restorers, tourists, and researchers.

Occurrence of Aspergillus niger strains on a polychrome cotton painting and their elimination by anoxic treatment

This study aimed to isolate and identify the population of filamentous fungi colonizing a cotton painting, whose conservation status was compromised and showed signs of biodeterioration due to dirt accumulation and microbial metabolism. In addition, microbiological techniques such as cultivation-dependent approach and molecular biology were used to identify microbial populations and to eliminate their metabolic action. For this, the nondestructive anoxic atmosphere technique was used, in which the microbial metabolism was affected by the absence of oxygen. Prior to exposure to an anoxic atmosphere, only one fungal species, Aspergillus niger, was identified at 12 points sampled in the obverse and reverse of the artwork; no fungal species persisted as a result of anoxic treatment. These results showed that exposure to anoxic conditions was effective for the total elimination of isolated fungal strains as well as their spores. In conclusion, this study proved the unprecedented effectiveness of a nondestructive technique for artwork on textile colonized by black fungi species. Thus, this interdisciplinary work involving conservation, microbiology, and chemistry presents a tool to eliminate microorganisms, while maintaining the integrity of artwork and safety of the restorer, that can be applied prior to artwork restoration.