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Microbiological Analysis in Three Diverse Natural Geothermal Bathing Pools in Iceland
Matis, Department of Food Safety, Environment and Genetics, Vínlandsleið 12, Reykjavík 113, Iceland
School of Engineering and Natural Sciences, University of Iceland, Sæmundargata 2, Reykjavík 101, Iceland
* Authors to whom correspondence should be addressed.
Received: 19 January 2013; in revised form: 22 February 2013 / Accepted: 8 March 2013 / Published: 14 March 2013
Abstract: Natural thermal bathing pools contain geothermal water that is very popular to bathe in but the water is not sterilized, irradiated or treated in any way. Increasing tourism in Iceland will lead to increasing numbers of bath guests, which can in turn affect the microbial flora in the pools and therefore user safety. Today, there is no legislation that applies to natural geothermal pools in Iceland, as the water is not used for consumption and the pools are not defined as public swimming pools. In this study, we conducted a microbiological analysis on three popular but different natural pools in Iceland, located at Lýsuhóll, Hveravellir and Landmannalaugar. Total bacterial counts were performed by flow cytometry, and with plate count at 22 °C, 37 °C and 50 °C. The presence of viable coliforms, Enterococcus spp. and pseudomonads were investigated by growth experiments on selective media. All samples were screened for noroviruses by real time PCR. The results indicate higher fecal contamination in the geothermal pools where the geothermal water flow was low and bathing guest count was high during the day. The number of cultivated Pseudomonas spp. was high (13,000–40,000 cfu/100 mL) in the natural pools, and several strains were isolated and classified as opportunistic pathogens. Norovirus was not detected in the three pools. DNA was extracted from one-liter samples in each pool and analyzed by partial 16S rRNA gene sequencing. Microbial diversity analysis revealed different microbial communities between the pools and they were primarily composed of alpha-, beta- and gammaproteobacteria.
Keywords: natural geothermal pool; bacterial count; microbiological parameters; cultured and uncultured bacteria; 16S rRNA gene sequencing
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Thorolfsdottir, B.O.T.; Marteinsson, V.T. Microbiological Analysis in Three Diverse Natural Geothermal Bathing Pools in Iceland. Int. J. Environ. Res. Public Health 2013, 10, 1085-1099.
Thorolfsdottir BOT, Marteinsson VT. Microbiological Analysis in Three Diverse Natural Geothermal Bathing Pools in Iceland. International Journal of Environmental Research and Public Health. 2013; 10(3):1085-1099.
Thorolfsdottir, Berglind O.T.; Marteinsson, Viggo T. 2013. "Microbiological Analysis in Three Diverse Natural Geothermal Bathing Pools in Iceland." Int. J. Environ. Res. Public Health 10, no. 3: 1085-1099.