Análise da biodiversidade microbiana em ambiente aquático com despejo contínuo de efluentes de hidrocarbonetos

Abstract

In the Amazon region, the Urucu Oil Province (Petrobras) has been disposing of hydrocarbon effluents into the surrounding aquatic environments since the beginning of its operations. The goal of this work was to analyze the bacterial biodiversity present in the dike of the effluents and in the stream before and after the disposal of hydrocarbon effluents. A study was conducted in two stages were carried out with the use of culture independent molecular techniques. The full genomic DNA of the sediment and water samples were extracted and used as templates in a PCR reaction with the use of specific oligonucleotides of the 16S rRNA gene bacteria domain. The PCR product was amplified and pyrosequenced, and the generated sequences were analyzed by the free software Mothur. The measurements of the physical-chemical and chromatographical parameters are within the measures established for these types of analyzed water bodies. In the first stage of the study, the taxonomic profiles of the samples have shown that the Proteobacteria phylum proved to be the most abundant together with the Deltaproteobacteria class and the gen known as Candidatus Solibacter. Similarly, in the second stage of the study, the Proteobacteria phylum proved to be the most abundant together with the Alphaproteobacteria class and the Geobacter gen predominant. Both genes are catalogued as bioremediators in contaminated environments, as well as 14% of the total genes. A large proportion of microorganisms were considered “Unclassified” (up to 30%). In first stage of the study the richness and the diversity of species in the Onça stream is greater following the disposal of hydrocarbon effluents, in second stage of the study the abundance and diversity of species in the natural stream (without a name in the region), is greater as compared to the same stream after the mixing of effluents. There is no significant statistical difference between the sample of the community in the natural stream and this effluent-mixed stream; and there is no difference in genetic structure among samples of each community analyzed, suggesting that the discharge of effluents in this body of water has no significant impact on the microbial biodiversity in this aquatic environment. This work, a pioneer in the taxonomic analysis of samples in dikes of effluents and streams with the disposal of effluents in the Urucu oil area, represents a challenge for understanding the relationship between the composition, abundance and diversity of microorganisms in this environment, and a rich source for the discovery of new taxonomic groups, as well as the huge potential for biotechnological exploration of such diversity.