Risk of biodeterioration of cultural heritage objects, stored in the historical and modern repositories in the Regional Museum in Rzeszow (Poland). A case study

- The microorganism concentrations were monitored in historic and modern museum depositories.
- In all depots the concentrations of bacteria were higher than fungi.
- In total, 19 bacteria and 10 fungal taxa were identified.
- P. expansum and M. luteus/lyla were found in 72% and 100% of the repositories, respectively.
- In the historic repositories the concentrations of bacteria were higher than in modern ones.

Museum artefacts are generally stored for a long period in repositories and are prone to microbiological colonisation. The goal of this research was to assess the risk of biodeterioration of artefacts stored in the Regional Museum in Rzeszow, Poland. The museum building consists of the historic and newly built parts and the aim was to verify the hypothesis about higher airborne concentrations of microorganisms in the historic part. In all repositories, the number of bacterial colonies was higher than those of fungi. The most polluted depots were those where different types of artefacts were stored. There were no differences in the number of fungal colonies in the repositories located in the historic and modern parts of the museum. The differences concerned only bacteria. The most common fungi were Penicillium expansum and Penicillium spp., while among bacteria Micrococcus luteus/lylae and Staphylococcus warneri. The highest microorganism biodiversity was in the historical depots and the lowest in the room with a book collection in the modern part of the museum. Findings showed that the microbial biota is not specific for either building type or the kind of artefact. Regarding bacteria, we detected the effect of 'historical building air'.