Caratterizzazione della comunità microbica coltivabile presente lungo la colonna d'acqua a Baia Terra Nova (Mare di Ross, Antartide)

The phylogenetic diversity of the cultivable bacterioplankton inhabiting Antarctic seawater was examined by genetic fingerprinting. The comparison of the restriction patterns obtained by ARDRA (Amplified Ribosomal DNA Restriction Analysis) led to subdivide the 604 isolates into 53 OTUs (Operational Taxonomic Units). Bacteria representing the class of Proteobacteria were dominant (68 %), followed by Actinobacteria (15 %). ?-Proteobacteria (9 %), Bacteroidetes (5 %) and, finally, Firmicutes (1 %). The 3 % of isolates have no known close relatives. Little differences were observed in the bacterioplankton composition both between the sites examined and within the same site. Phenotypic investigation put on evidence the predominance of Gram-negative, rod-shaped and motile bacteria. The majority of them were catalase positive, oxidase negative, psychrotrophic and able to grow in a wide range of salt concentration.