The polar ice caps play a key part in providing an understanding of climate variability over the last eight glacial cycles and may give information about paleoenvironmental features and changes of microbial diversity in the past. Microbiological studies on polar ice cores are rare and focused so far on silty or accreted ice. Aim of our studies is to detect, characterize, and compare the prokaryotic diversity in different Arctic and Antarctic ice cores at different depths in order to learn more about relations of past and recent communities and about alterations of ancient communities in relation to climatic changes. Critical points in ice core analytics are the strong contaminations of the outside of ice cores as well as the limited availability of sample material. Hence, preparation/decontamination protocols were tested and adapted with inoculated and artificially contaminated ice cores. Our work on real older glacial ice started with material from the uppermost 200 m of the ice shield of Dronning Maud Land, Antarctica. Some pollen grains and a low abundance of bacteria cells were detected by Sybr Green staining in combination with solid phase cytometry. From 3 other ice core samples from about 130-179 m depth, approximately 2150 years old, DNA could be extracted and amplified. DGGE-analyses of amplified DNA revealed a low bacterial diversity, but one strong DGGE band-only present in the inner part of two of the three ice cores analyzed- could be affiliated to the alpha-proteobacteria with a high similarity to Bradyrhizobium japonicum. Clone libraries and metagenomic studies supported the dominance of this bacterial type that might jointly be responsible for N2O abnormalities in glacial ice cores.