Abstract
Glacier microorganisms are an ideal target for studies of the functionalities, structures, and environmental responses in ecosystems due to the simpler structure of the glacier ecosystem. Phylogenetic analyses of bacteria revealed the presence of the particular bacteria growing in the glacier environment and adapting to the particular micro-environment. Bacterial communities in the glaciers were divided into three types based on their habitat: snow-covered or snow- and ice- covered or bare-ice areas. In addition, the bacteria trapped in ice cores are now regarded as novel environmental markers for the past environment. Bacteriological analyses of ice cores have the potential to reconstitute the past environment. Since many intestinal bacteria were detected in the snow samples, we have conducted studies about antibiotic-resistant genes in the glacier environment. This is because animal intestines are the best places for selection and propagation of antibiotic-resistant bacteria. The detection of antibiotic-resistant bacteria in glaciers, which are very far from human industrial activity, implies human impact on nature. Here, we show the prevalence of antibiotic-resistant genes in 54 snow and ice samples collected from the Arctic, Antarctic, Central Asia, North and South America, and Africa, to evaluate the level of human impact on the environment. Antibiotic-resistant genes are widely distributed in Central Asia, North and South America, Greenland, and Africa. In contrast, Antarctic glaciers (>70° S) were virtually free of these genes. Our results suggest the major origin (northern hemisphere) and transmission (atmospheric circulation) of these genes.
