Two state-of-the-art methods for the study of microbial communities will be implemented for use on Antarctic environmental samples: Automated Ribosomal Spacer Analysis (ARISA) and parallel-tagged pyrosequencing of ribosomal RNA genes. ARISA permits a thorough comparison of the microbial community in a large number of samples along a gradient of humidity and allows a well-founded selection of samples for pyrosequencing.