Prokaryotic in Antarctic permafrost: abundances and metabolism in the Northern Victoria Land and Upper Victoria Valley.

Our contribution is devoted to test the hypothesis that Continental Antarctic permafrost harboured prokaryotic communities rich in viable cells and metabolic potentials. With this aim, three permafrost cores collected in Boulder Clay (Northern Victoria Land) were examined for the prokaryotic abundance, viability, and potential metabolism using culture-indedependent methods. Samples were analysed by microscopic image-analysis to assess abundance and cell-shape determinations and by flow-cytometry to recognise sub-populations according to nucleic acid contents. The quantification of viable and respiring cells was performed by image analysis using the Live/Dead and 5-Cyano-2,3-ditolyl-tetrazolium chloride stains, respectively. The potential ectoenzymatic activities rates on proteinaceous (leucine-aminopeptidase) and glucidic (ß-glucosidase) organic matter and on organic phosphates (alkaline-phosphatase) were determined as well as the physiological profiles by Biolog-Ecoplate(TM). In comparison, another permafrost sample, collected from the Dry Valleys (Upper Victoria Valley), was analysed with the same methods.