Microbiological diversity and microbial related risks at Wawel Royal Castle in Krakow, Poland

Microorganisms are known to colonize and modify various environments, including cultural heritage buildings. Anthropogenic indoor environments often provides specific conditions for microbial growth e.g. microclimatic parameters. These conditions are potentially easy to control thus it is advisable to characterize and monitor bacterial and fungal communities in indoor habitats. Microbiological pollution in museums is particularly important because bacteria and fungi contribute to the deterioration of cultural heritage objects and may have a negative impact on people’s health. In our study we performed microbiological analysis of Wawel Royal Castle in Krakow, which is one of the greatest Polish national heritage, and was visited by over 1.4 million tourists in 2017. There are large and valuable collections of objects related to the Polish rulers e.g. rare tapestries and paintings. Microbiome analysis was done by culture-dependent experiments for I) airborne microorganisms (50 litres of air) sampled onto various types of agar media, as well as culture-independent analysis of II) airborne microorganisms (12000 litres of air) sampled onto saline, and III) microbes from dust from historical surfaces. Microbiological diversity was determined by analysis of deep sequenced amplicons covering hypervariable regions V3V4 of 16S rDNA gene and ITS2 region located between 5.8S and 26S rDNA.