Large heterotrophic bacterial diversity of Antarctic samples through cultivation

The microbial diversity on Antarctica is largely under-explored. As part of the AMBIO-project that aims to explore the factors affecting bacterial distribution patterns in Antarctica, nine samples from different regions were investigated. They include two samples from the environment of the Princess Elisabeth Station (Utsteinen, Dronning Maud Land): BB50 and BB115; two samples from the Trans-Antarctic Mountains: TM2 from Forlidas Pond (Pensacola Mountains) and TM4 from Lundström Lake (Shackleton Mountains); a littoral sample PQ1 from Pourquoi-Pas Lake (Pourquoi-Pas Island); samples LA3 (Langhovde Peninsula), SK5 (Skarvsness Peninsula) and WO10 (West Ongul Island) from three lakes at Lützow-Holm Bay, Syowa and sample SO6 from the Schirmacher Oasis. Samples were investigated with a culture-dependent approach using different media (MA, R A, R2A/10 and PYGV) and incubation temperatures (4, 15 and 20°C). Between 254 and 573 isolates were obtained from each sample and were dereplicated with the rep-PCR fingerprinting technique. Representatives of each rep-cluster were used in partial 16S rDNA sequencing for identification. The preliminary results of the 16S rDNA sequencing show a large diversity, distributed over the major phylogenetic groups. Actinobacteria and Alphaproteobacteria are well represented in all samples and Bacteroidetes and Betaproteobacteria are found in lower amounts whereas Deinococci, Gammaproteobacteria and Firmicutes are only isolated from some samples. Despite the large diversity and the fact that some samples originate from the same general area, only little overlap between the samples was observed. Some of the isolates, especially in the Sphingobacteria and Deinococci show low 16S rDNA sequence similarity values with known sequences and may represent new taxa.