Livingston Island (South Shetland Islands) is characterised by a maritime polar climate with temperatures above 0°C for 4 months and a mean annual precipitation of 450 mm. Nine vertical profiles were investigated regarding to their geochemical and geophysical properties and their microbial community structures. Two of the sites were covered by mosses and showed initial soil formation and humus accumulation. Total carbon and total nitrogen contents were low except for the upper layers of the moss covered sites. Denaturing gradient gel electrophoresis (DGGE) fingerprints from amplified 16S rRNA gene fragments showed large varieties in the vertical profiles and between the different sites. Most of the sequences obtained from re-amplified DGGE bands belong to the Bacteriodetes and Acidobacteria phyla. We also found sequences affiliated to methanotrophic bacteria (Methylobacter, Methylocapsa, Methylocystis) as well as to microorganisms involved in the nitrogen cycle (Nitrospira, Nitrospina). Furthermore, it was possible to isolate pure cultures, which belong mainly to Arthrobacter and Pseudomonas but also members of Frigoribacterium, Devosia, Leifsonia, Subtercola and Mucilaginibacter could be isolated. Although nutrient content is low a distinct diversity of microorganisms can be found in these extreme habitats dominated by so far unknown species
