PROKARYOTIC DIVERSITY IN ONE OF THE LARGEST HYPERSALINE COASTAL LAGOONS IN THE WORLD

Joyce Lemos Lima (UFRJ); Leonardo Henriques Pinto (FIOCRUZ); Gigliola Rhayd Boechat Sallôto (UFRJ); Maysa Beatriz Mandetta Clementino (FIOCRUZ); Ricardo Pilz Vieira (UFRJ); Orlando Bonifácio Martins (UFRJ)

Araruama Lagoon is an environment characterized by high salt concentrations. The rainfall and high evaporation rates in this region favored the development of many salty ponds around the lagoon. In order to reveal the microbial composition of this system, we applied a polyphasic approach, including microbiological and metagenomic methods. The samples were cultivated on Halobacterium medium at several salt concentrations and performed a 16S rRNA gene survey of Archaea and Bacteria domains. Pigmented colonies (red to pink) selected from hipersaline medium (30%) were submitted to electronic microscopic, biochemical assays and 16S rDNA sequencing analysis to check the taxonomic and phylogenetic groups. Sequencing database analysis revealed new species of Haloarcula and Haloferax genera. Among the metagenomic approach, most archaeal clones were related to uncultured environmental Euryarchaeota. In lagoon water, we found some clones related to Methanogenic archaea, while in the saline pond water members related to the genus Haloarcula were detected. Bacterial community was dominated by clones related to Gamma-proteobacteria, Actinobacteria, and Synechococcus in lagoon water, while Salinibacter ruber relatives dominated in saline pond. The detection of a substantial number of clones related to uncultured archaea and bacteria suggest that the hypersaline waters of Araruama harbor a pool of novel prokaryotic phylotypes, distinct from those observed in other similar systems. We also observed clones related to halophilic genera of cyanobacteria that are specific for each habitat studied. This is the first study of the biogeography and community structure of microbial assemblages in Brazilian tropical hypersaline environments. The main goal of this work is the description of the first halophilic archaea from Brazil and to obtain a better understanding of the free-living prokaryotic diversity adapted to life in hypersaline waters.