Jolanta Pollesch

Changes in the concentration of microbial aerosol were examined in the selected premises of the Jagiellonian University Museum in Kraków, made available to visitors during the Night of Museums, i.e. Hall, Libraria and Treasury. The samples were collected four times using the collision method with MAS-100 air sampler. The concentration of mesophilic and heamolytic bacteria, molds, staphylococci and actinomycetes was examined and an attempt was made to find the correlation between the number of museum visitors and the concentration of microbial aerosol. The smallest number of visitors (600 persons) was recorded in Libraria, while the greatest (900 persons) in the Hall. The prevalence of microorganisms varied significantly between the hours of sampling, from the smallest number in the morning, after opening, to the greatest recorded while there were most visitors (9 p.m.). The largest number of molds was observed after the museum was closed (0:30). A strong positive correlation was found between the concentration of airborne mesophilic bacteria and actinomycetes with the number of visitors, the concentration of fungi was negatively correlated and there was a weak positive correlation in the case of staphylococci. On average, the greatest concentration of mesophilic bacteria (860 CFU/m3), actinomycetes (60 CFU/m3) and staphylococci (26 CFU/m3) was recorded in the Hall at 9 p.m. The largest concentration of molds (1,290 CFU/m3) was found in the Hall and Treasury at 0:30. The observed concentrations of airborne microorganisms do not exceed acceptable levels for public utility premises, therefore they do not pose a threat to the health of the Museum employees, tourists and to the condition of the Museum collections. 

This study was aimed to assess the seasonal variability of microbial aerosol concentrations in the Jagiellonian University Museum and the fungal contamination of the selected exhibits shown or stored in the JUM. The air contamination analysis was conducted four times per year by air collision method. The concentrations of mesophilic bacteria, mold fungi, actinomycetes and staphylococci were examined in the magazine of exhibits in the attic, at the Olszewski Hall (exposure), in the wooden frames magazine in the basement and the Museum cafe. External background was the Professors’ Garden. In the study sites air temperature was measured during each sampling. The surface contamination of the Museum exhibits was examined by the collection of swabs. Seasonal differences in the concentration of the analyzed microorganisms were observed: the concentration of all microbial groups – except fungi – was the highest in summer, when the temperature in all tested sites was the highest. On the other hand, the highest concentrations of fungi in the tested premises were observed in autumn and spring. The smallest levels of mesophilic bacteria and staphylococci were observed in winter, while the smallest amounts of actinomycetes were found in spring and autumn. The smallest concentrations of fungi in all examined sites occurred in spring. The concentrations of the analyzed microorganisms did not exceed the limit values, except in one case – i.e. actinomycetes in the Museum cafe in summer. The surfaces of the exhibits were colonized by fungal strains that can be potentially dangerous to human health or cause biodeterioration, but only one object (the Wyspiański painting) was damaged by a harmful strain of Penicillium italicum. Other objects showed no losses due to microbial degradation, which proves effective conservation and lack of optimum conditions for fungal colonization. We also found a relationship between the concentration of microbial aerosol and the conditions in the studied sites, and therefore the season of the year. Also the type and utility character of the premises determined the bioaerosol concentrations. However, the observed concentrations of airborne microorganisms do not pose a direct threat to the Museum employees or its visitors.