Influence of the bacterioplankton community of a tropical eutrophic lagoon on the bacterial community of its neighbouring ocean |
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Authors: | Rodrigo Gouvêa Taketani Fábio Vieira de Araújo Fabiana de Souza Cannavan Siu Mui Tsai Alexandre Soares Rosado |
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Institution: | 1.Laboratório de Ecologia Microbiana Molecular, Instituto de Microbiologia, Universidade Federal do Rio de Janeiro,Rio de Janeiro,Brazil;2.Departamento de Ciências, Faculdade de Forma??o de Professores,Universidade do Estado do Rio de Janeiro,Rio de Janeiro,Brazil;3.Centro de Energia Nuclear na Agricultura (CENA),Universidade de S?o Paulo,Piracicaba,Brazil;4.Instituto de Microbiologia Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, CCS–Bloco E subsolo, Ilha do Fund?o.,Rio de Janeiro,Brazil |
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Abstract: | The Rodrigo de Freitas lagoon (RFL) is a tropical eutrophic coastal ecosystem located in the urban area of Rio de Janeiro,
Brazil. This environment consists of freshwater but has communication with the ocean through a channel (Jardim de Alah’s Channel).
The aim of this study was to evaluate the influence of lagoon water on the nearby ocean using molecular and traditional microbiological
methods. We hypothesised that due to the eutrophic low-salinity environment, the bacterioplankton community from the RFL would
have a native “brackish” composition influenced by both freshwater and marine phylotypes, and that bacterial phylotypes of
this community would be detected in oceanic samples closer to the channel between the lagoon and the ocean. The cultivation
and microscopy experiments clearly showed this influence. Bacterial cell counts revealed that the greater amounts of bacterial
cells present in the lagoon increased the observed values seen at oceanic stations near the channel. The Denaturing gradient
gel eletrophoresis community profiles also showed a clear influence of Rodrigo de Freitas lagoon waters on the adjacent beaches.
The band patterns found for the stations near the channel showed that these communities were mixtures of the communities of
the lagoon and sea, and as the distance from the channel increased, the samples became more similar to ocean bacterial communities.
A 16S rRNA gene clone library was constructed using a sample acquired from the connection point between the lagoon and the
ocean. Around 52% of the sequences in the library showed similarity to the genus Proteobacteria (1% Alpha, 21% Beta, 19% Gamma and 29% unclassified Proteobacteria), and the second most abundant genus was Bacteroidetes, with 15% of the total clones. The results showed that the structure of the bacterial community had both freshwater and marine
characteristics. |
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