RESUMO
Abstract Studies on the bacterial diversity associated with wild plants are rare, especially on those that grow in association with bromeliads. In the present study, we isolated and identified epiphytic and endophytic bacteria from the roots of the bromeliads Dyckia excelsa, Dyckia leptostachya and Deuterocohnia meziana occurring in the "cangas" in the Pantanal from Mato Grosso do Sul State, Brazil. The epiphytic bacteria were isolated from washed roots, while the endophytic bacteria were isolated from surface disinfested roots. Bacterial representatives corresponding to each BOX-PCR fingerprint, as well as those that did not result in amplicons, were selected for 16S rDNA gene sequence analysis. The BOX-PCR data showed intrageneric and intraspecific diversity and could discriminate strains and identify their phenotypic characteristics. The 16S rDNA gene sequence and phylogeny analysis showed a higher occurrence of strains belonging to the genus Bacillus than Mycobacterium and Brevibacterium, which were found in lower numbers. Species from the Bacillus genus are well known for their sporulation capacity and longer survival in arid locations, such as the "cangas". This study clearly showed that the bromeliad species represent a vast reservoir of bacterial community diversity, and the cultivable strains represent a new source for biotechnological prospecting.
Resumo Estudos sobre a diversidade bacteriana associada a plantas silvestres são raros, especialmente naqueles que crescem em associação com bromélias. No presente estudo, isolamos e identificamos bactérias epífitas e endofíticas das raízes das bromélias Dyckia excelsa, D. leptostachya e Deuterocohnia meziana ocorrentes nas "cangas" no Pantanal do Mato Grosso do Sul, Brasil. As bactérias epifíticas foram isoladas de raízes lavadas, enquanto as bactérias endofíticas foram isoladas de raízes desinfestadas na superfície. Representantes bacterianos correspondentes a cada perfil do BOX-PCR, bem como aqueles que não resultaram em amplificações, foram selecionados para o sequenciamento do gene 16S rDNA. Os dados da BOX-PCR mostraram diversidade intragênica e intraespecífica e puderam discriminar cepas e identificar suas características fenotípicas. A seqüência do gene 16S rDNA e a análise filogenética mostraram uma maior ocorrência de cepas pertencentes ao gênero Bacillus do que as bactérias Mycobacterium e Brevibacterium, encontradas em menor número. Espécies do gênero Bacillus são bem conhecidas por sua capacidade de esporulação e maior sobrevida em locais áridos, como as "cangas". Este estudo mostrou claramente que as espécies de bromélias representam um vasto reservatório de diversidade de comunidades bacterianas, e as linhagens cultiváveis podem representar uma nova fonte para a prospecção biotecnológica.
Assuntos
Bactérias/genética , Biodiversidade , Filogenia , Brasil , DNA Bacteriano/genética , RNA Ribossômico 16S/genética , Raízes de PlantasRESUMO
Studies on the bacterial diversity associated with wild plants are rare, especially on those that grow in association with bromeliads. In the present study, we isolated and identified epiphytic and endophytic bacteria from the roots of the bromeliads Dyckia excelsa, Dyckia leptostachya and Deuterocohnia meziana occurring in the "cangas" in the Pantanal from Mato Grosso do Sul State, Brazil. The epiphytic bacteria were isolated from washed roots, while the endophytic bacteria were isolated from surface disinfested roots. Bacterial representatives corresponding to each BOX-PCR fingerprint, as well as those that did not result in amplicons, were selected for 16S rDNA gene sequence analysis. The BOX-PCR data showed intrageneric and intraspecific diversity and could discriminate strains and identify their phenotypic characteristics. The 16S rDNA gene sequence and phylogeny analysis showed a higher occurrence of strains belonging to the genus Bacillus than Mycobacterium and Brevibacterium, which were found in lower numbers. Species from the Bacillus genus are well known for their sporulation capacity and longer survival in arid locations, such as the "cangas". This study clearly showed that the bromeliad species represent a vast reservoir of bacterial community diversity, and the cultivable strains represent a new source for biotechnological prospecting.
Assuntos
Bactérias , Biodiversidade , Bactérias/genética , Brasil , DNA Bacteriano/genética , Filogenia , Raízes de Plantas , RNA Ribossômico 16S/genéticaRESUMO
Abstract Studies on the bacterial diversity associated with wild plants are rare, especially on those that grow in association with bromeliads. In the present study, we isolated and identified epiphytic and endophytic bacteria from the roots of the bromeliads Dyckia excelsa, Dyckia leptostachya and Deuterocohnia meziana occurring in the cangas in the Pantanal from Mato Grosso do Sul State, Brazil. The epiphytic bacteria were isolated from washed roots, while the endophytic bacteria were isolated from surface disinfested roots. Bacterial representatives corresponding to each BOX-PCR fingerprint, as well as those that did not result in amplicons, were selected for 16S rDNA gene sequence analysis. The BOX-PCR data showed intrageneric and intraspecific diversity and could discriminate strains and identify their phenotypic characteristics. The 16S rDNA gene sequence and phylogeny analysis showed a higher occurrence of strains belonging to the genus Bacillus than Mycobacterium and Brevibacterium, which were found in lower numbers. Species from the Bacillus genus are well known for their sporulation capacity and longer survival in arid locations, such as the cangas. This study clearly showed that the bromeliad species represent a vast reservoir of bacterial community diversity, and the cultivable strains represent a new source for biotechnological prospecting.
Resumo Estudos sobre a diversidade bacteriana associada a plantas silvestres são raros, especialmente naqueles que crescem em associação com bromélias. No presente estudo, isolamos e identificamos bactérias epífitas e endofíticas das raízes das bromélias Dyckia excelsa, D. leptostachya e Deuterocohnia meziana ocorrentes nas cangas no Pantanal do Mato Grosso do Sul, Brasil. As bactérias epifíticas foram isoladas de raízes lavadas, enquanto as bactérias endofíticas foram isoladas de raízes desinfestadas na superfície. Representantes bacterianos correspondentes a cada perfil do BOX-PCR, bem como aqueles que não resultaram em amplificações, foram selecionados para o sequenciamento do gene 16S rDNA. Os dados da BOX-PCR mostraram diversidade intragênica e intraespecífica e puderam discriminar cepas e identificar suas características fenotípicas. A seqüência do gene 16S rDNA e a análise filogenética mostraram uma maior ocorrência de cepas pertencentes ao gênero Bacillus do que as bactérias Mycobacterium e Brevibacterium, encontradas em menor número. Espécies do gênero Bacillus são bem conhecidas por sua capacidade de esporulação e maior sobrevida em locais áridos, como as cangas. Este estudo mostrou claramente que as espécies de bromélias representam um vasto reservatório de diversidade de comunidades bacterianas, e as linhagens cultiváveis podem representar uma nova fonte para a prospecção biotecnológica.
RESUMO
In an ecological survey of nitrogen-fixing bacteria isolated from the rhizosphere and as endophytes of sugarcane, maize and teosinte plants in Brazil, Mexico and South Africa, a new phylogenetically homogeneous group of N(2)-fixing bacteria was identified within the genus Burkholderia. This polyphasic taxonomic study included microscopic and colony morphology, API 20NE tests and growth on different culture media at different pH and temperatures, as well as carbon source assimilation tests and whole-cell protein pattern analysis. Analysis of 16S rRNA gene sequences showed 99.2-99.9 % similarity within the novel species and 97.2 % similarity to the closest related species, Burkholderia sacchari. The novel species was composed of four distinct amplified 16S rDNA restriction analysis groups. The DNA-DNA reassociation values within the novel species were greater than 70 % and less than 42 % for the closest related species, B. sacchari. Based on these results and on many phenotypic characteristics, a novel N(2)-fixing species is proposed for the genus Burkholderia, Burkholderia tropica sp. nov., with the type strain Ppe8(T) (=ATCC BAA-831(T)=LMG 22274(T)=DSM 15359(T)). B. tropica was isolated from plants grown in geographical regions with climates ranging from temperate subhumid to hot humid.
