Predominance of Roseobacter, Sulfitobacter, Glaciecola and Psychrobacter in seawater collected off Ushuaia, Argentina, Sub-Antarctica

Bacterial diversity in sub-Antarctic seawater, collected off Ushuaia, Argentina, was examined using a culture independent approach. The composition of the 16S rRNA gene libraries from seawater and seawater contaminated with the water soluble fraction of crude oil was statistically different (P value 0.001). In both libraries, clones representing the Alphaproteobacteria, Gammaproteobacteria, the Cytophaga–Flavobacterium–Bacteroidetes group and unculturable bacteria were dominant. Clones associated with the genera Roseobacter, Sulfitobacter, Staleya, Glaciecola, Colwellia, Marinomonas, Cytophaga and Cellulophaga were common to both the libraries. However, clones associated with Psychrobacter, Arcobacter, Formosa algae, Polaribacter, Ulvibacter and Tenacibaculum were found only in seawater contaminated with hydrocarbons (Table 1). Further, the percentage of clones of Roseobacter, Sulfitobacter and Glaceicola was high in seawater (43%, 90% and 12% respectively) compared to seawater contaminated with hydrocarbons (35%, 4% and 9% respectively). One of the clones F2C63 showed 100% similarity with Marinomonas ushuaiensis a bacterium identified by us from the same site. Comparison of 16S rRNA gene clones of seawater and seawater contaminated with the water-soluble fraction (WSF) of crude oil collected off Ushuaia, Argentina, Sub-Antarctica The nucleotide accession numbers of the clones are given in round brackets. The percentage values within square brackets represent the percentage similarity of the 16S rRNA gene sequence of the clones with the nearest phylogenetic neighbour. The bold numericals in columns two and three indicate the number of clones in the particular class or genus. The clones which are in bold font represent unidentified and unculturable bacteria which have been assigned to the nearest phylogenetic neighbour based on their affiliations in the phylogenetic trees (Figs 1 and 2). The remaining clones which did not identify with any known phylogenetic neighbour are listed at the end of the table. Comparison of 16S rRNA gene clones of seawater and seawater contaminated with the water-soluble fraction (WSF) of crude oil collected off Ushuaia, Argentina, Sub-Antarctica The nucleotide accession numbers of the clones are given in round brackets. The percentage values within square brackets represent the percentage similarity of the 16S rRNA gene sequence of the clones with the nearest phylogenetic neighbour. The bold numericals in columns two and three indicate the number of clones in the particular class or genus. The clones which are in bold font represent unidentified and unculturable bacteria which have been assigned to the nearest phylogenetic neighbour based on their affiliations in the phylogenetic trees (Figs 1 and 2). The remaining clones which did not identify with any known phylogenetic neighbour are listed at the end of the table.