Análise da diversidade taxonômica e funcional da comunidade microbiana de um ambiente lótico urbano

Abstract

Rivers and streams are important reservoirs of fresh water available for consumption. The increasing urbanization represents a threat to these ecosystems. Specifically, the discharge of sewage alters the content of nutrients and may affect the composition of the microbial community. This study aimed to know the genetic and functional diversity of the microbial community from an urban lotic environment. Samples of water were collected from two areas of São Pedro stream, one urbanized and the other not influenced by urbanization. The dissolved nutrient content was analyzed. To identify and quantify microbes involved in the nitrogen cycle and potentially pathogenic bacteria PCR and FISH analysis were performed. In order to know the taxonomic and functional profile of the microbial community of this lotic environment, metagenomic analysis was carried out. High concentration of dissolved nutrients was observed on the urbanized area. The PCR and FISH results showed higher incidence of microbes involved on nitrogen cycle and potentially pathogenic bacteria on the urbanized area of the stream. The taxonomic profile indicates that the non-urbanized environment had relatively homogeneous distribution of bacterial groups with the predominance of Proteobacteria. The urbanized metagenome had a higher number of sequences concentrated on specifics phyla: Proteobacteria (Betaproteobacteria e Gammaproteobacteria), Bacteroidetes and Firmicutes. Genera and species related to pathogenicity were also prevalent on the urbanized area. The functional profile indicated that the microbes are acting on the metabolism of methane, nitrogen and sulfur especially on the urbanized area. It was also observed that genes related to virulence (antibiotic resistance and metal resistance) and stress response are spread on the urbanized environment. These results indicate a structural change of the microbial community imposed by anthrophic actions.