The majority (› 80%) of the Earth’s biosphere is permanently exposed to temperatures below 5°C. Psychrophilic microorganisms have successfully colonized these cold environments because they have evolved special mechanisms to overcome the life-endangering influence of low temperature. Our studies focus on biodiversity and microbial community structures in various alpine habitats, such as glacier cryoconite, cold soils and sediments. By using polyphasic taxonomy, we described so far 27 novel species and 4 novel genera. To exploit the biotechnological potential of psychrophilic microorganisms, we investigate their physiological properties.