Date Published: November 17, 2017
Publisher: Springer Netherlands
Author(s): Elżbieta Gębarowska, Wojciech Pusz, Jolanta Kucińska, Włodzimierz Kita.
The aim of this work was to determine the genera or species composition and the number of colony forming units of airborne bacteria and fungi, respectively, in two salt mines in Poland “Wieliczka” (Lesser Poland) and “Polkowice–Sieroszowice” (Lower Silesia). Both of them are working environments characterized by extreme conditions, and additionally “Wieliczka,” officially placed on the UNESCO World Heritage Sites’ list, plays a role of tourist attraction. There are also some curative chambers located in this mine. Air samples were taken once in December 2015, between 6:00 a.m. and 9:00 a.m. There were nine measurement points located about 200 m underground in “Wieliczka” and six measurement points located in the working shafts about 400 m underground in “Polkowice–Sieroszowice.” The total volume of each air sample was 150 L. Air samples, collected in individual measurement points of both salt mines, were inoculated on two microbiological media: potato dextrose agar and tryptic soy agar using the impact method. We identified 10 and 3 fungal genera in the “Wieliczka” Salt Mine and in “Polkowice–Sieroszowice,” respectively. The most common were fungi of the Penicillium genus. In both mines, the Gram-positive bacteria of genus Micrococcus were detected most frequently. Among identified microorganisms, there were neither pathogenic fungi nor bacteria. The most prevalent microorganisms detected in indoor air were Gram-positive cocci, which constituted up to 80% of airborne microflora. Our results showed that microorganisms recorded in the air samples are not a threat to workers, tourists or patients. Neither pathogens nor potentially pathogenic microorganisms, listed as BSL-2, BSL-3 or BSL-4, were detected. The microbes identified during our analysis commonly occur in such environments as the soil, water and air. Some of the detected bacteria are component of natural microflora of human skin and mucous membranes, and they can cause only opportunistic infections in individuals depending on their health condition.
The purity of the atmospheric air is one of the basic issues of the evaluation procedure of work space quality. Particular attention should be paid to bioaerosols that are ubiquitous in indoor air and potentially harmful to human health. Although the air is considered to be an inimical environment for the reproduction of microorganisms, they are able to endure there and maintain their infectious skills. Bioaerosol, also referred to as organic dust, is usually composed of pathogenic and non-pathogenic bacteria, viruses, fungal spores, matter of plants and animals as well as their primary and secondary metabolites including the bacterial endotoxins or mycotoxins. They are transmitted through airborne route, droplet route, vector-borne route, by direct contact and less by the oral route. The saprophytic and infectious bioaerosols are considered to worsen hygienic conditions contributing to the human allergy. They may cause a waste of food, construction materials and pharmaceuticals. Bioaerosols are also responsible for transmission of many of human, animal and plant infectious diseases, mycosis, upper respiratory infections, viral diseases, fire blight and many others (Douwes et al. 2003; Górny 2004; Heikkinen et al. 2005; https://oshwiki.eu/wiki/Bioaerosols_and_OSH).
In the literature, little is known about bioaerosol composition in indoor air of the mines. Some of these places are not only workplaces but also touristic attractions, as well as the place where some people are cured (Frączek and Grzyb 2010; Grzyb and Frączek 2010; Frączek and Górny 2011; Frączek et al. 2013). In this research, the microbiological analysis of indoor air in two Polish salt mines (“Wieliczka” and “Polkowice–Sieroszowice”) was performed. It was determined the genera or species composition and the number of colony forming units (CFU) of airborne bacteria and fungi. “Wieliczka” Salt Mine, officially placed on the UNESCO World Heritage Sites’ list, plays a role of tourist attraction visited by hundreds of people per day and there are also some curative chambers. Both mines are working environments in extreme conditions; however, there are not legal regulations that would determine the suggested limits of airborne bacteria and fungi in atypical types of workplaces.