Abstract

Evaluation of 64oC and 76oC dry saunas as an environment for survival and growth of mesophilic and thermophilic bacteria

Author(s): Jae Ran Seo, Bong Su Kim, Doo Hyun Park

In this study, the diversity and variations of bacteria that were sampled from the floor of dry saunas operated at 64°C and 76°C for 6 days (Monday–Saturday) wereanalyzed to determineif the bacteria contaminating the dry saunas can grow, survive, or die. Bacteria sampled from the 64°C sauna grew at 45°C and 60°C but those from the 76°C sauna didnot growat either45°C or60°C. Sixteen and eightspecies of bacteria grewat 45°C and 60°C,respectively. Eight of 16 species grown at 45°C werethermophiles and all bacteria grown at 60oCwerethermophiles. DNA of non-growing bacteria sampled from a 76°C sauna wasdirectly extracted and analyzed by temperature gradient gel electrophoresis (TGGE). The non-growing bacteria included13 species based onthe band number of16S-rDNA separatedby TGGE. Thermophilescontaminating the64°C sauna were more frequently detected than mesophilesover the6 experimental days. Most of the mesophiles may have temporarily survivedand some of thermophilic bacteria survived for 4–5 days during sampling for the 6 days,whereas all bacteria contaminating the76°C sauna may lose their physiological function in a short time by drying out.