Resumo

Harboring activities stand out as important threats to coastal ecosystems. Pollutants are released during routine and/or accidental activities and could lead to disastrous consequences for biotic and abiotic components of the ecosystems. Taking in accounting the role of microbial community for resilience of disturbed habitats, the aim of this study was to access the diversity of microbial communities from sediments under influence of two big and different seaports of Ceará, Brazil. Mucuripe (MUC) and Pecem (PEC) ports differ in physical structures, depth and times of operation; Pecem is a 12-years-old off-shore port while Mucuripe is a traditional one, active for 50 years. Samples were collected in 15 different stations in MUC and 10 in PEC. For each port, all samples were pooled for DNA extraction and subjected to 454-pyrosequencing. The resulting 16S rRNA sequences were submitted to classification in the RDP II database. A total of 238 sequences were extracted, 173 for PEC and 65 for MUC. Both ports were dominated by Bacteria, with the phyla Proteobacteria, Chloroflexi, Firmicutes, Planctomycetes, Acidobacteria, Actinobacteria, and Bacteroidetes. Verrucomicrobia, Cyanobacteria, and Deferribacteres were exclusive of PEC. The more abundant phylum in both ports was Proteobacteria (46.7% in MUC; and 40.4%, PEC). In this phylum, most of the sequences belonged to delta-Proteobacteria (44.6% in PEC; 32.1%, MUC) and gamma-Proteobacteria (30.8% in PEC; 46.4%, MUC). Delta-proteobacteria were dominated by Desulfobacterales (69% in PEC; 77.8%, MUC), with the families Desulfobubaceae and Desulfobacteraceae accounting for 60% and 35% in PEC, and 57% and 42% in MUC, respectively. Gamma-proteobacteria consisted of about 90% of unclassified sequences, with Alteromonadales accounting for 10% in PEC and Chromatiales for 7.7% in MUC. From the sequences affiliated to Archaea, about 25% belonged to the phylum Crenarchaeota in both ports. The 16S rRNA taxonomic profiles of both ports proved to be very similar, indicating that physical structure and operational activities of the ports have little influence on the microbial community composition.