Contents of Research
The purpose of this study was to comprehensively survey Legionella spp. and other waterborne pathogens that colonize Syowa Station, and to identify their potential sources.
From December 2018 to January 2019, as part of the 60th Japanese Antarctic Research Expedition, samples were collected from water facilities such as water reservoirs in Syowa Station, and glacial lakes located in ice-free areas in the vicinity of the station. These samples were brought back to Japan and were further analyzed. DNA was extracted from each sample, PCR-amplified targeting regions used for bacterial classification. These PCR products were comprehensively sequenced to analyze bacterial communities. Also, PCR amplification targeting specific regions for Legionella spp. was conducted to obtain a detailed understanding of their presence and distribution.
Analysis of the lake samples revealed that genera including pathogenic species such as Legionella spp., Pseudomonas spp., and Mycobacterium spp., are widely distributed in natural lakes. Legionella spp. was confirmed in all surveyed lakes. Furthermore, detailed analysis of the community structure of Legionella spp. confirmed that unexpectedly diverse Legionella spp. are distributed even in cold Antarctic lakes. Most of the Legionella-derived 16S rRNA gene sequences detected in this study had low sequence similarity with the previously described Legionella species, suggesting the wide distribution of yet-described species in Antarctica.
Comparison of the Legionella spp. community detected at the station with that found in natural lakes revealed some sequences common to both communities, but a large proportion of the sequences from the community detected at the station were closely related to those of known pathogenic species. The rarity of detection of these species in Antarctic lakes suggests that they may have been introduced through human activities. Legionella spp. were not detected in water samples from the taps at the Syowa station (after water purification treatment).