Orientador: Manoel Victor Franco Lemos / Banca: Ricardo Antonio Polanczyk / Banca: Sabrina Moutinho Chabregas / Banca: Janete Apparecida Desidério Sena / Banca: Antonio Sérgio Ferraudo / Resumo: A bactéria B. thuringiensis caracteriza-se pela produção de proteínas tóxicas a representantes de diversas ordens de insetos, as quais são codificadas por genes cry. Este trabalho foi realizado com objetivo de selecionar isolados de B. thuringiensis por meio da caracterização morfológica e molecular identificando as diferentes subclasses dos genes cry3, cry7, cry8, cry9 e cry35 e determinar a patogenicidade contra Sphenophorus levis, que é uma das mais importantes pragas da cultura da cana-de-açúcar. Foram utilizados 1128 isolados de B. thuringiensis e com a observação em microscópio com contraste de fases foram confirmadas como pertencentes à espécie de B. thuringiensis e três linhagens padrões. O material genético foi extraído pela matriz de troca iônica "Instagene Matrix" e submetido a PCR com iniciadores gerais cry3, cry7, cry8, cry9 e cry35 identificando-se 45 isolados com produto de amplificação para coleópteros, os quais juntamente com as linhagens padrões de B. thuringiensis var. tenebrionis, var. morrissone e var. tolworthi e testemunhas foram utilizados para a realização do bioensaio. A análise discriminante alocou os isolados em três grupos quanto à toxicidade de B. thuringiensis e os grupos ficaram assim definidos: um grupo de BAIXA efetividade, com 19,60% do total dos isolados, nesse grupo ficaram as testemunhas e uma linhagem padrão B. thuringiensis var. morrissone e isolados do LGBBA; um grupo de MÉDIA efetividade, com 66,67% do total dos isolados, nesse grupo ficaram duas linhagens padrões B. thuringiensis var. tolworthi e var. morrissone e isolados do LGBBA e um grupo com ALTA efetividade com 13,72% do total dos isolados do LGBBA, os quais podem ser considerados promissores no controle biológico de S. levis. / Abstract: Molecular characterization and selection of B. thuringiensis isolates exhibiting potential control on Sphenophorus levis larvae. Bacillus thuringiensis is characterized by the production of toxic proteins to insects from a number of different orders which are coded by the cry genes. This work was developed aiming to select B. thuringiensis isolates using morphological and molecular analysis so as to identify different cry genes subclass for cry3, cry7, cry8, cry9 and cry35 and also to determine the pathogenicity levels against Sphenophorus levis larvae, that is one of the most important sugar-cane pests. As much as 1128 bacterial isolates together with three control strains were used and for the phase contrast microscopy and molecular analysis. The genetic materials were obtained using the Instagene Matrix that is an ionic matrix and the PCR primers used were developed for cry3, cry7, cry8, cry9 and cry35 genes. A total of 45 isolates were selected showing possible amplicons for coleopterans. These isolates together with the standard strains B. thuringiensis var. tenebrionis, var. morrissone a var. tolworthi were used for bioassays. A discriminating analysis has allocated the bacterial isolates within three groups of B. thuringiensis toxicity and these groups were defined as one with LOW effectivity, comprising 19,6% of the isolates and the control strains together with one of the control strains B. thuringiensis var. morrissone. Another group has revealed a MEDIAN effectivity with a total of 66.7% of the isolates including two other control strains B. thuringiensis var. tolworthi e var. morrissone and a third group with HIGH effectivity with 13.7% of the isolates which were considered as promising B. thuringiensis isolates for the control of S. levis larvae. / Doutor

Orientadora: Eliana Gertrudes Macedo Lemos / Banca: Maria José Valarini / Banca: Haroldo Alves Pereira Junior / Banca: Lúcia Maria Carareto Alves / Banca: Maria Inês Tiraboschi Ferro / Resumo: Bactérias simbiontes conhecidos como rizóbios interagem com raízes de leguminosas e induzem a formação de nódulos fixadores de nitrogênio. Em rizóbios, genes essenciais para simbiose são compartimentalizados em ilhas simbióticas ou em ilhas no cromossoma. Para o entendimento da estrutura e evolução dessas ilhas simbióticas, é necessário analisar seu contexto genético e sua organização. O genoma parcial de B. elkanii SEMIA 587 apresenta hoje um total de 5.821.111 pb seqüenciados contendo 62,6 % de GC em 3941 Contigs, onde foram identificados 5381 ORFs. Uma suposta ilha simbiótica foi localizada através da identificação de genes relacionados à fixação e nodulação em comparação à ilha simbiótica de B. japonicum, encontrando 267 ORFs em B. elkanii, onde 17 ORFs foram identificadas como transposases. Assim, através destes resultados parciais pode ser possível averiguar que B. elkanii provavelmente sofreu um rearranjo genético no cromossoma, já que ele apresenta um tamanho menor que B. japonicum em relação ao tamanho do genoma. / Abstract: Symbiont bacteria, commonly known as rhizobia interact with root legume and induce the formation of Nitrogen-fixing nodules. Among rhizobia, essential genes for symbioses are compartmentalized either in symbiotic islands or in chromosomal islands. For better understanding of the structure and evolution of these symbiotic islands, it is necessary to analyze their genetic context and organization. The work had as objective to analyze genes related to the symbiotic island in the partial genoma of the B. elkanii strain 587 has 5.821.111 bp sequenced, containing 62,6 % of GC in 3941 Contigs, been identified 5381 ORFs. A purported symbiotic island was localized through of the identification of related genes of fixing nitrogen and nodulation in comparison with the symbiotic island of B. japonicum, founding 267 ORFs in B. elkanii, where 17 ORFs were identified as transposases. So through these partial results could be possible to infer that B. elkanii probably shows a symbiotic island with genetic rearrange into chromosome, because it showed lower genome size than B. japonicum. / Doutor

No description available.

A field experiment was conducted in the Ridge and Valley region of Virginia near Blacksburg during the 1989 through 1991 corn-rye growing seasons. The treatments in this experiment consisted of varying amounts of ¹⁵N-depleted fertilizer N applied to corn (Zea mays L.) at planting followed by a winter rye (Secale cereale L.) cover crop treatment. The research was divided into four studies. The first study was conducted to evaluate an analytical procedure that could be used for the diffusion of low masses of ¹⁵N-labeled NH₄ in 2M KCI and subsequent analysis for N recovery and ¹⁵N concentrations in soil by direct combustion mass spectrometry. Diffusion was found to be a suitable technique for preparing low-mass N samples for automated ¹⁵N analysis by Automated Nitrogen-Carbon Analysis/Mass Spectrometry (ANCA/MS). Recoveries of low masses of added N were quantitative, and accurate ¹⁵N concentrations were obtained when the results were corrected for isotope dilution due to background or contaminant N. The second study was conducted to determine if ¹⁵N-depleted fertilizer N could be satisfactorily used as a tracer of residual fertilizer N in plant tissue and various soil N fractions through a corn-winter rye crop rotation. Fertilizer-derived N in the soil NO₃-N fraction following corn harvest was clearly detectable and distinguishable from natural abundance to a 90-cm depth. Detection of fertilizer N in the total N pool below the 30-cm depth was not reliable, particularly at the lower N rates. Clay-fixation of fertilizer N measured at corn harvest was not detected by ¹⁵N analysis. Inconclusive results indicate that further research is needed to determine the feasibility of using depleted material for measuring clay-fixation of fertilizer-derived NH₄⁺-N. Nitrogen uptake by a winter rye cover crop reduced soil NO₃-N levels below that required for accurate isotope-ratio analysis. Following winter fallow (approx. 1 yr after fertilizer application) residual ¹⁵N-depleted fertilizer N was still detectable in plant tissue and the soil NO₃-N fraction. The objectives of the third study were to measure plant uptake and soil distribution of fertilizer N applied to corn at varying N rates and to determine the relationships between economic optimum N rate, fertilizer-use efficiency, and potential leaching loss of residual fertilizer N to groundwater. Plant recovery of fertilizer N in 1989 ranged from 33 to 47% even though no grain yield and fertilizer N uptake response resulted from N fertilization. Greatest accumulation of residual fertilizer N was found in the surface 30-cm both years following corn harvest. The economic optimum N rate for 1990 corn planted into a rye mulch (218 kg N ha⁻¹) corresponded closely with the rate (224 kg N ha⁻¹) resulting in the highest fertilizer-use efficiency. Low levels of residual fertilizer-derived NO₃ in the 60-90-cm depth following the 1990 corn harvest provides evidence to support the use of the economic optimum N rate concept from both economic and environmental viewpoints. The fourth study was designed to measure the effectiveness of a winter rye cover crop for recovering residual fertilizer N from the previous application of varying N rates to corn. Recovery of fertilizer N by winter rye increased with increasing N rate applied to the previous corn crop and ranged from 3.5 to 35.9 kg N ha⁻¹ in 1990 and 2.3 to 25.7 kg N ha⁻¹ in 1991. Residual fertilizer N recovery in 1991 was higher in rye plots where the previous corn crop had been planted no-till into rye stubble as compared to corn planted no-till into rye mulch. Little or no fertilizer-derived mineral N was measured in the soil to a final depth of 90-cm following a winter rye cover crop. Amounts of fertilizer-derived mineral N increased with depth and previous fertilizer N rate applied to corn following winter fallow. These results provide evidence to support the use of a winter rye cover crop on a silt loam soil to recover residual fertilizer-derived mineral N that might otherwise be lost to groundwater. / Ph. D.

Nitrogenase fixation occurred in a number of habitats in and nearby several antarctic lakes. The observed acetylene reduction occurred in bluegreen algal mats in littoral areas that received maximal sunlight. The benthic bluegreen algal communities in reduced light under 5-6 m of permanent ice showed no detectable nitrogenase activity. The observed nitrogen fixation potential correlated with the presence of heterocystous bluegreen algae considered to be the major nitrogen fixing organisms in these habitats. The relatively low acetylene reduction rates suggest that a small but significant contribution of ammonia to these environments deficient in nitrogen may occur through nitrogen fixation. / Master of Science

Sinorhizobium meliloti est une bactérie du sol Gram- capable d'induire la formation denodosités fixatrices d'azote lors d'une interaction symbiotique avec les plantes de la familledes légumineuses. L'importance de la balance redox au cours de cette interaction a été miseen évidence. Ainsi, des mutants bactériens déficients dans la production du glutathion (GSH),présentent un phénotype altéré d'infection et de fixation de l'azote atmosphérique.Le premier objectif a donc été de déterminer si les phénotypes observés chez les mutants de lavoie de biosynthèse du GSH étaient liés à l'activité des glutarédoxines (GRX). Une analysebioinformatique a révélé la présence de trois gènes codant des GRX chez S. meliloti. Lesmutants, Smgrx1, Smgrx2 et Smgrx3, déficients pour chacune des GRX, ne produisent pasdes phénotypes similaires à ceux observés avec les mutants GSH. Si Smgrx2 présente unphénotype moins marqué, Smgrx1 est plus sévèrement affecté puisqu'il n'est plus capable dese différencier en bactéroïde. L'implication de SmGrx2 dans la régulation du métabolisme dufer et la mise en place des centres Fe-S a, par ailleurs, été mise en évidence.Le second objectif a été de définir s'il existait, chez S. meliloti, une redondance fonctionnelleentre les GRX et les thiorédoxines (TRX). Ainsi, le mutant SmtrxB, dépourvu de thiorédoxineréductase, présente la particularité d'induire la formation d'un plus grand nombre de nodulesque la souche sauvage. Le système TRX de S. meliloti apparaît donc comme un régulateurnégatif de la nodulation. D'autre part, les nodosités formées par ce mutant SmtrxB, ont uneactivité fixatrice d'azote significativement diminuée. Les rôles des TRX et des GRXapparaissent donc, au moins partiellement, distincts.Les résultats obtenus ici apportent des éléments nouveaux sur l'implication du GSH, des GRXet des TRX dans la mise en place d'une nodosité fonctionnelle, et ouvrent de nouvellesperspectives d'études sur les rôles de ces molécules dans le processus de fixation d'azote. / Sinorhizobium meliloti is a soil bacterium Gram- able to induce the formation of nitrogenfixingnodules during a symbiotic interaction with plants of the legume family. Theimportance of redox balance during this interaction has been demonstrated. In this way,bacterial mutants deficient in the production of glutathione (GSH), exhibit an alteredphenotype of infection and fixation of atmospheric nitrogen.The first objective was therefore to determine whether the phenotypes observed in mutants ofthe GSH biosynthesis pathway were related to the activity of glutaredoxins (GRX). Abioinformatic analysis revealed the presence of three genes encoding GRX in S. meliloti. Themutants, Smgrx1, Smgrx2 and Smgrx3, deficient for each of the GRX, do not producephenotypes similar to those observed with the GSH mutants. If Smgrx2 presents a less severephenotype, Smgrx1 is more severely affected since it is incapable of differentiating intobacteroïd. The involvement of SmGrx2 in the regulation of iron metabolism and theestablishment of Fe-S cluster has also been demonstrated.The second objective was to determine if there was, in S. meliloti, a functional redundancybetween GRX and thioredoxin (TRX). Thus, the SmtrxB mutant, devoid of thioredoxinreductase, has the distinctive feature of inducing the formation of more nodules than the wildtype strain. The TRX system of S. meliloti appears to be a negative regulator of nodulation.On the other hand, the nodules formed by this SmtrxB mutant have a significantly decreasednitrogen-fixing activity. Hence, the roles of TRX and GRX appear to be at least partiallydistinct.The results obtained here provide new evidence on the involvement of GSH, the GRX andTRX in the establishment of a functional nodule, and open new perspectives for studying onthe roles of these molecules in the process of nitrogen fixation.

A cana-de-açúcar (Saccharum sp.) é uma planta que ocupa posição de destaque entre as culturas de importância econômica no cenário internacional, principalmente no Brasil, que é o maior produtor mundial. O estudo da diversidade microbiana associada a plantas, principalmente aquelas com interesse comercial, apresenta-se como importante alternativa para melhorar as características e a sustentabilidade destas culturas. Neste sentido, bactérias endofíticas e rizobactérias tem sido alvo de muitos estudos, pois apresentam efeitos benéficos para as plantas, como promoção de crescimento e inibição de patógenos. Um dos grupos de bactérias que colonizam a cana-de-açúcar é composto por espécies do gênero Burkholderia. Este gênero é composto de bactérias que podem ser encontradas em diferentes nichos ecológicos, como o solo, a água, ou em associação com plantas, fungos, e outros animais, além de humanos. Na interação bactéria-planta, as espécies de Burkholderia podem colonizar a rizosfera e o interior das raízes hospedeiro, onde podem estimular o crescimento do vegetal, contribuir para sua nutrição, como também protegê-lo da ação de fitopatógenos. Sendo assim, isolados de Burkholderia spp. do interior das raízes (endofíticos) e da rizosfera de cana-de-açúcar foram avaliados quanto à capacidade de fixar nitrogênio, produzir AIA, sideróforos, enzimas de interesse biotecnológico, solubilizar fosfato inorgânico e inibir patógenos desta cultura. Estes isolados também foram caracterizados geneticamente por análise de restrição e seqüenciamento dos genes 16S rDNA e gyrB, além da caracterização genotípica por BOX-PCR. Os resultados indicam que os isolados possuem potencial para promoção de crescimento vegetal, inibição de patógenos e produção de lipases. Filogeneticamente, a maioria dos isolados pertencem ao complexo Burkholderia cepacia com similaridade à B. cepacia e B. cenocepacia. Considerando a ocorrência dos isolados como endófitos ou rizosféricos, as metodologias fenotípicas e genotípicas não foram capazes de distinguir os membros componentes destas comunidades. Este trabalho evidencia a ampla associação deste grupo com cana-de-açúcar, e destaca as possíveis aplicações que tais bactérias podem ter no cultivo e sustentabilidade desta cultura. / Sugarcane (Saccharum spp.) occupies a position of prominence among the economically important crops in the international scene, mainly in Brazil, which is the world\'s largest producer. The study of microbial diversity associated with plants, especially those with commercial interest, presents itself an important alternative to improve the performance and sustainability of these crops. In this sense, endophytic bacteria and rhizobacteria has been target of many studies, since they have beneficial effects for plants, such as plant growth promotion and inhibition of pathogens. One of the bacterial groups that colonize sugarcane is composed of species of the genus Burkholderia. This genus is composed of a bacterium that can be found in different ecological niches, such as soil, water, or in association with plants, fungi and other animals, as well as in humans. In the association bacterium-plant, the species of Burkholderia can colonize the rhizosphere and the inside of the host roots, which can stimulate the growth of the plant, contributing to its nutrition, but also protects it from the action of phytopathogens. Thus strains of Burkholderia spp. isolated from the inside of the roots (endophytic) and from the rhizosphere of sugarcane were evaluated for the ability to fix nitrogen, produce IAA, siderophores, enzymes of biotechnological interests, solubilize inorganic phosphate and inhibits pathogens of the same crop. These strains were also genetically characterized by the analysis of enzymatic restriction and sequencing of 16S rDNA and gyrB genes, in addition to the characterization by genotypic technique BOX-PCR. The results indicate that the strains have potential for plant growth promotion, inhibition of pathogens and production of lipases. Phylogenetically, the isolates were affiliated to Burkholderia cepacia complex, with mainly similarity to B. cepacia and B. cenocepacia. Considering the occurrence of isolated as endophytes or rhizosphere, the genotypic and phenotypic methods were not able to distinguish the members of these communities. This research work demonstrates the broad association that this group has with sugarcane, and highlights the possible applications that these bacteria may have in cultivation and sustainability of this crop.

A intensificação ecológica das plantações florestais tropicais (PFT) pela introdução de árvores fixadoras de nitrogênio (AFN) pode levar a maior produção de biomassa e ao aumento dos serviços ecossistêmicos (e.g. manutenção dos recursos hídricos e da biodiversidade, recuperação de áreas degradas e sequestro de carbono). Essa intensificação é particularmente importante nos trópicos, por causa da escassez de solos ricos em nutrientes destinados ao estabelecimento das PFT, e devido aos altos custos ambientais e econômicos do uso de fertilizantes minerais. A facilitação a partir de AFN para não-AFN ocorre pela transferência de N após a decomposição da serapilheira, resíduos culturais, raízes e nódulos e exudados radiculares; ou diretamente com auxílio de redes de micorrizas em comum. Foi usado o traçador 15N para adquirir novas percepções sobre a funcionalidade do nitrogênio de plantações florestais puras e mistas de Eucalyptus e Acacia. O capítulo 2 aborda a variação sazonal da fixação do N2 pela Acacia mangium numa segunda rotação florestal com monoculturas (1111 plantas ha-1) ou associada com Eucalyptus grandis (com 555 plantas por espécie ha-1) (em Itatinga-SP). A competição com árvores de Eucalyptus reduziu o crescimento da Acacia em mistura. Em contraste, Eucalyptus em mistura obtiveram maior crescimento e conteúdo de N por árvore do que em monocultura. Maior fixação de N2 pela Acacia em mistura do que em monocultura pode ser relacionado a mais alta competição das árvores de Eucalyptus do que de Acacia para o N do solo. A maior mineralização do N no monocultivo da Acacia do que no plantio misto após uma rotação florestal pode reduzir a fixação de N2 no monocultivo de Acacia durante a segunda rotação florestal em comparação ao plantio misto. O capítulo 3 focou sobre a transferência de N em curto prazo e abaixo do solo a partir da A. mangium para E. grandis vizinhos, com monitoramento durante 60 dias em um plantio misto com 1111 plantas espécie-1ha-1 (Itatinga-SP). 15N-NO3- foi injetado no fuste de três árvores dominantes de Acacia (com 26 meses de idade). A maior parte das folhas, raízes finas e rizosfera das duas espécies foram enriquecidas com 15N a partir dos 5 dias após a marcação, até 6,2 m a partir da Acacia marcada. Esse estudo destacou que a transferência de N em curto prazo e abaixo do solo poderia prover quantidades significativas do requerimento de N de árvores vizinhas as AFN em florestas mistas. O capítulo 4 abordou os efeitos de resíduos de colheita (RC: folhas, galhos e casca) de A. mangium e E. grandis sobre a dinâmica do N no solo e serapilheira, a absorção de N pelas árvores e a produção de biomassa durante a rotação seguinte de Eucalyptus em monocultivo com 1667 plantas ha-1 (Bofete-SP). O conteúdo de N nos RC da Acacia foi cerca de 3 vezes maior do que RC de Eucalyptus. Os resultados preliminares mostraram que a transferência de N a partir de RC da Acacia para o solo e para árvores de Eucalyptus foi mais rápida (observados aos 3 meses após o replantio) do que a partir de RC de E. grandis (observado aos 7 meses após o replantio). Outros estudos relacionados aos temas abordados em cada capítulo são apresentados nos Apêndices. Esta tese destaca o potencial de uso de AFN para promover a intensificação ecológica de PFT. / Ecological intensification of tropical forest plantations (TFP) through the introduction of nitrogen-fixing trees (NFTs) may lead to higher biomass production and to enhancement of ecosystem services (e.g. maintenance of water resources and biodiversity, land reclamation and carbon sequestration). Such intensification can be particularly important in tropics, because of the scarcity of nutrient-rich land area devoted for TFP, and environmental and economic constraints with the use of mineral fertilizers. Facilitation from NFTs to non-NFTs can occur through N-transfer after decomposition of litter, roots and nodules and pruning residues, roots exudates or through common mycorrhizal networks. We used 15N tracers to gain insights into nitrogen functioning of pure and mixed-species plantations of Eucalyptus and Acacia. Chapter 2 deals with the seasonal variation of N2 fixation by Acacia mangium in a second stand rotation of monoculture (1111 trees ha-1) or associated with Eucalyptus grandis (with 555 trees ha-1 for each species) (in Itatinga-SP). Competition with Eucalyptus trees depleted Acacia tree growth in mixture. By contrast, individual Eucalyptus tree growth and N content were higher in mixed-species plantations than in monoculture. Higher N2 fixation by Acacia in mixture than in pure stand may be linked to higher competition of Eucalyptus trees than Acacia trees for soil N. Higher soil N mineralization in pure Acacia stand than in mixture after one stand rotation may deplete N2 fixation in Acacia monoculture during the second rotation in comparison to mixture. Chapter 3 focuses on the short-term belowground N transfer from A. mangium to E. grandis neighbors, monitored during 60 days in a mixed-species plantation with 1111 trees ha-1 for each species (Itatinga-SP). 15N-NO3- was injected in the stem of three big Acacia trees (26 months of age). Most of leaves, fine roots and rhizosphere samples of both species were 15N enriched from 5 days after labelling onwards, up to 6.2 m from the labelled Acacias. Our study highlights that short-term belowground N transfer may provide significants amounts of the N requirements of neighbors of N-fixing trees in mixed-species forests. Chapter 4 deals with the effect of harvested residues (HRs: leaves, branches and bark) of A. mangium and E. grandis on litter and soil N dynamics, N tree uptake and tree biomass production during a following rotation of Eucalyptus in monoculture with 1667 trees ha-1 (Bofete-SP). N content of Acacia HRs was 3 times higher than of Eucalyptus HRs. Our preliminary results showed that N transfer from Acacia HR to the soil and to replanted Eucalyptus trees was more rapid (3 months after replanting) than from N transfer from E. grandis HRs (7 months of age). Other studies related to the chapters are presented in Appendices. Our study highlights the potential use of the NFTs to promote the ecological intensification of TFP.

The NRT2 (high affinity nitrate transporter 2) family is a part of the iHATS (inducible high affinity system) that studies have shown is responsible for the influx of nitrate into the plant cell after provision of nitrate. The ZmNRT2.1 from Zea mays was constitutively expressed in Nicotiana tabacum. To assess how over-expression of this foreign NRT2.1 affects nitrate influx by plants, nitrate content in leaf and root tissue, gene expression, and vegetal growth were analyzed in media with deficient or high nitrate concentrations (0.1, 1, or 10 mM). Compared to wild type plants: the transgenic lines had a significantly larger fresh weight in all nitrate conditions; primary root length was significantly longer in the 0.1 and 1 mM nitrate conditions; both the fresh weight and the primary root length were significantly higher when 50 mM NaCl was applied as a stress factor to medias containing 0.1 and 10 mM nitrate. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

A cana-de-açúcar (Saccharum sp.) é uma planta que ocupa posição de destaque entre as culturas de importância econômica no cenário internacional, principalmente no Brasil, que é o maior produtor mundial. O estudo da diversidade microbiana associada a plantas, principalmente aquelas com interesse comercial, apresenta-se como importante alternativa para melhorar as características e a sustentabilidade destas culturas. Neste sentido, bactérias endofíticas e rizobactérias tem sido alvo de muitos estudos, pois apresentam efeitos benéficos para as plantas, como promoção de crescimento e inibição de patógenos. Um dos grupos de bactérias que colonizam a cana-de-açúcar é composto por espécies do gênero Burkholderia. Este gênero é composto de bactérias que podem ser encontradas em diferentes nichos ecológicos, como o solo, a água, ou em associação com plantas, fungos, e outros animais, além de humanos. Na interação bactéria-planta, as espécies de Burkholderia podem colonizar a rizosfera e o interior das raízes hospedeiro, onde podem estimular o crescimento do vegetal, contribuir para sua nutrição, como também protegê-lo da ação de fitopatógenos. Sendo assim, isolados de Burkholderia spp. do interior das raízes (endofíticos) e da rizosfera de cana-de-açúcar foram avaliados quanto à capacidade de fixar nitrogênio, produzir AIA, sideróforos, enzimas de interesse biotecnológico, solubilizar fosfato inorgânico e inibir patógenos desta cultura. Estes isolados também foram caracterizados geneticamente por análise de restrição e seqüenciamento dos genes 16S rDNA e gyrB, além da caracterização genotípica por BOX-PCR. Os resultados indicam que os isolados possuem potencial para promoção de crescimento vegetal, inibição de patógenos e produção de lipases. Filogeneticamente, a maioria dos isolados pertencem ao complexo Burkholderia cepacia com similaridade à B. cepacia e B. cenocepacia. Considerando a ocorrência dos isolados como endófitos ou rizosféricos, as metodologias fenotípicas e genotípicas não foram capazes de distinguir os membros componentes destas comunidades. Este trabalho evidencia a ampla associação deste grupo com cana-de-açúcar, e destaca as possíveis aplicações que tais bactérias podem ter no cultivo e sustentabilidade desta cultura. / Sugarcane (Saccharum spp.) occupies a position of prominence among the economically important crops in the international scene, mainly in Brazil, which is the world\'s largest producer. The study of microbial diversity associated with plants, especially those with commercial interest, presents itself an important alternative to improve the performance and sustainability of these crops. In this sense, endophytic bacteria and rhizobacteria has been target of many studies, since they have beneficial effects for plants, such as plant growth promotion and inhibition of pathogens. One of the bacterial groups that colonize sugarcane is composed of species of the genus Burkholderia. This genus is composed of a bacterium that can be found in different ecological niches, such as soil, water, or in association with plants, fungi and other animals, as well as in humans. In the association bacterium-plant, the species of Burkholderia can colonize the rhizosphere and the inside of the host roots, which can stimulate the growth of the plant, contributing to its nutrition, but also protects it from the action of phytopathogens. Thus strains of Burkholderia spp. isolated from the inside of the roots (endophytic) and from the rhizosphere of sugarcane were evaluated for the ability to fix nitrogen, produce IAA, siderophores, enzymes of biotechnological interests, solubilize inorganic phosphate and inhibits pathogens of the same crop. These strains were also genetically characterized by the analysis of enzymatic restriction and sequencing of 16S rDNA and gyrB genes, in addition to the characterization by genotypic technique BOX-PCR. The results indicate that the strains have potential for plant growth promotion, inhibition of pathogens and production of lipases. Phylogenetically, the isolates were affiliated to Burkholderia cepacia complex, with mainly similarity to B. cepacia and B. cenocepacia. Considering the occurrence of isolated as endophytes or rhizosphere, the genotypic and phenotypic methods were not able to distinguish the members of these communities. This research work demonstrates the broad association that this group has with sugarcane, and highlights the possible applications that these bacteria may have in cultivation and sustainability of this crop.