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Previous issue date: 2013-03-13 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / In the 1960? the mining company Plumbum Mineradora was installed in the Satate of Bahia, Brazil. This company, which produced lead ingots for 33 years, left over 400,000 tons of slag, which contained, among other pollutants, cadmium and lead. These metals are currently found in the soil surrounding the old factory, in concentrations considered highly toxic.
A study was started to investigate possible bioremediation in the area with the isolation of bacteria from the rhizosphere of local plants, followed by the test in their performance in metals contaminant tolerance. Finally, identification of the bacteria was made based on molecular marker 16S rRNA. The isolation protocol was carry out using Nutrient Agar and after obtaining a pure culture. The isolates were then subjected to tests of Minimum Inhibitory Concentration (CIM). Each isolate served as a source for extraction of DNA for molecular analysis with 16S rRNA region.
Among the rhizospheres collected, those from which the greatest number of species were isolated from plants with a perennial habit, among them the castor bean (Ricinus communis L.) and emba?ba (Cecropia pachystachya Tr?cul) which together comprised approximately 38% of all species of bacteria obtained. Interestingly, from the castor bean (an exotic plant in Brazil), 2/3 of the bacteria were Gram negative, while from the emba?ba (a native plant of Brazil), ? of the bacteria isolated were of Gram positive. Regardless of the classification of Gram, the bacteria studied showed higher tolerance to lead; 70% of Gram negative bacteria showed conspicuous morphological changes, whereas of those that were Gram positive, only 13% demonstrated. In addition, these bacteria have been identified by molecular analysis using the 16S rRNA marker. The used methodology based on analysis of parsimony and distance trees. As a result, the region 16S was able to identify only 22% of species while the remain species could only be identified to genus or to infra-generic groups. Therefore, the data suggest that the Gram negative and Gram positive bacteria have distinct mechanisms of adaptation in environments polluted by lead and cadmium and that the 16S region is not an efficient universal barcode marker, which should be used only as the first step on the identification of bacteria. Although this study does not provide a final parameter for ecological factors under consideration here, it provides an insight into the influence of the plant habitat on bacterial communites, and the role of Gram in the mechanisms of tolerance. It is hope to explore these aspects in the further studies. / Na d?cada de 60, a empresa de minera??o Plumbum Mineradora foi instalada no Estado da Bahia, Brasil. Esta empresa, a qual produziu lingotes de chumbo por 33 anos, deixou mais de 400.000 toneladas de esc?ria, a qual continha, dentre outros poluentes, c?dmio e chumbo. Estes metais s?o, atualmente, encontrados no solo do entorno das antigas instala??es da f?brica, em concentra??es consideradas altamente t?xicas. Este estudo come?ou a investigar a biorremedia??o da ?rea com o isolamento de bact?rias das rizosferas de plantas locais, seguido por testar a toler?ncia das bact?rias a esses metais. Finalmente, a identifica??o de bact?rias foi feita baseada no marcador molecular 16S rRNA. O protocolo de isolamento foi realizado em meio de Agar Nutriente e ap?s a obten??o de cultura pura, os isolados foram submetidos a testes de Concentra??o Inibit?ria M?nima (CIM). Cada isolado serviu de fonte para extra??es de DNA para an?lise molecular com a regi?o 16S rRNA. Dentre as rizosferas coletadas, as que mais se destacaram em rela??o a quantidade de esp?cies isoladas foram as plantas de h?bito perene, dentre elas, a mamona (Ricinus comunis L.) e a emba?ba (Cecropia pachystachya Tr?cul), que abrigaram juntas aproximadamente 38% de todas as esp?cies de bact?rias obtidas. Interessante notar que da mamona (uma planta ex?tica no Brasil), 2/3 das bact?rias foram Gram negativas, enquanto que da emba?ba (uma planta nativa do Brasil), 3/4 das bact?rias isoladas foram Gram positivas. Independentemente da classifica??o do Gram, as bact?rias apresentaram maior resist?ncia ao chumbo; 70% das Gram negativas apresentaram mudan?as morfol?gicas acentuadas, enquanto que estas, nas Gram positivas, manifestaram-se em apenas 13%. Al?m disso, estas bact?rias foram identificadas por meio de an?lise molecular, com o uso do marcador 16S rRNA. A metodologia usada foi baseada em an?lise de ?rvores de parcim?nia e dist?ncia. Como resultado, a regi?o 16S foi capaz de identificar 22% das esp?cies, enquanto que para o restante mostrou-se eficiente para classifica??o at? g?nero ou para agrupamentos infragen?ricos. Portanto, os dados sugerem que as bact?rias Gram negativas e Gram positivas possuem mecanismos de adapta??es distintos em ambientes polu?dos por chumbo e c?dmio e que a regi?o 16S n?o ? eficiente como marcador universal tipo ?c?digo de barras?, o qual deve ser utilizado apenas como a primeira ferramenta de identifica??o de bact?rias isoladas. Apesar deste estudo n?o servir como par?metro definitivo para considera??es ecol?gicas, ele fornece conhecimento sobre a influ?ncia do h?bito da planta sobre a comunidade bacteriana e o papel da estrutura morfol?gica das bact?rias (Gram) nos mecanismos de toler?ncia. Espera-se que estes dados possam ser explorados em estudos posteriores.
| Identifer | oai:union.ndltd.org:IBICT/oai:tede2.uefs.br:8080:tede/254 |
| Date | 13 March 2013 |
| Creators | Souza, Adriana Fidelis Couto |
| Contributors | Esposito, Elisa |
| Publisher | Universidade Estadual de Feira de Santana, Mestrado Acad?mico em Biotecnologia, UEFS, Brasil, DEPARTAMENTO DE CI?NCIAS BIOL?GICAS |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da UEFS, instname:Universidade Estadual de Feira de Santana, instacron:UEFS |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 7701973706309601282, 600, 600, 600, 600, -6971480722008537872, -1634559385931244697, 2075167498588264571 |
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