Phylogenetic identification of marine bacteria isolated from deep-sea sediments of the eastern South Atlantic Ocean

The deep-sea environments of the South Atlantic Ocean are less studied in comparison to the North Atlantic and Pacific Oceans. With the aim of identifying the deep-sea bacteria in this less known ocean, 70 strains were isolated from eight sediment samples (depth range between 1905 to 5560 m) collected in the eastern part of the South Atlantic, from the equatorial region to the Cape Abyssal Plain, using three different culture media. The strains were classified into three phylogenetic groups, Gammaproteobacteria, Firmicutes and Actinobacteria, by the analysis of 16s rRNA gene sequences. Gammaproteobacteria and Firmicutes were the most frequently identified groups, with Halomonas the most frequent genus among the strains. Microorganisms belonging to Firmicutes were the only ones observed in all samples. Sixteen of the 41 identified operational taxonomic units probably represent new species. The presence of potentially new species reinforces the need for new studies in the deep-sea environments of the South Atlantic.

We would like to thank the captain, the crew of the R/V Akademik Loffe and the Academy of Sciences, Russia, for the support during the cruise. We are grateful for Dr. José Angel Alvarez Perez coordinator of the project “Patterns and Processes of the Ecosystems of the Southern Mid-Atlantic” – Census of Marine Life (CoML), for the support to the cruise and to Dr André Silva Barreto for the collection of the samples. We also acknowledge the International Centre for Genetic Engineering and Biotechnology (ICGEB) and the Brazilian National Council for Scientific and Technological Development (CNPq, Process 577915/2008-8) for financial support.