Resumo

Polycyclic aromatic hydrocarbons (PAHs) are natural organic compounds, generated by incomplete combustion of organic matter. Petroleum activities are introduced into the environment large quantity of PAHs, resulting in contamination of ecosystems. The native microorganisms capable of degrading toxic compounds and used for bioremediation are very important, the metagenome is an alternative for the identification and analysis of these microorganisms cannot be cultivated. The present study shows the microorganisms found in ecosystems of 3 states in northeastern Brazil (RN, CE, PB), which revealed 10 metagenomes samples of soil and water. The soil was collected from river sediment saline, mangroves, caatinga and Atlantic Forest and water samples from the estuary and ocean. The metagenomic libraries generated by pyrosequencing were subjected to computer analysis MG-RAST. Among the bacteria were the most abundant phyla: Proteobacteria, Actinobacteria, Acidobacteria and Firmicutes. In metagenomes caatinga biome phylum Actinobacteria was predominant, in others, Proteobacteria was dominant. In most metagenomas, the predominant class Alphaproteobacteria was followed by Gammaproteobacteria. The affiliations of the sequences in the KEGG database allowed to map key enzymes that may be involved in the process of metabolism and degradation of metagenomas evaluated. Among the identified functional categories, the 5 dominant based on the relative abundance were clustering-based subsystems (11.2%), carbohydrates (7.5%), protein metabolism (6.2%), amino acids and derivatives (6.1%), miscellaneous (5.9%) and metabolism of aromatic compounds 1.3%. The majority of the sequences are related to a benzoate degradation pathway, which is a central intermediate compound in the metabolism of other aromatic compounds such as toluene, xylene, carbazole, biphenyl, etc. In most metagenomas enzyme benzaldehyde dehydrogenase showed the highest number of hits related, it is involved in the pathways of degradation of other aromatic compounds such as xylene, toluene and aminobenzoate. This work helps in better understanding of the microbiology of these environments. In addition to the specific ecological composition of these environments, sediments and water also have a specific microbiota and future work should focus on a complete description of the metabolic pathways of these microorganisms.