Resumo: A adoção de práticas conservacionistas contribui para a recuperação da fertilidade dos so... more Resumo: A adoção de práticas conservacionistas contribui para a recuperação da fertilidade dos solos, proporcionando uma redução do uso de fertilizantes sintéticos. Devido a capacidade de formar nódulos com ampla faixa de rizóbio, tem-se utilizado a adubação verde com leguminosas para ciclagem de nutrientes e disponibilização de nitrogênio para as plantas. Nesse contexto, a identificação da população nativa de rizóbio associada aos adubos verdes pode ser um instrumento para melhorar a contribuição da fixação biológica de nitrogênio nos sistemas agrícolas. O trabalho objetivou caracterizar morfologicamente bactérias isoladas de nódulos de três espécies de Crotalaria, oriundas de área de cultivo orgânico. Após a coleta dos nódulos, procedeu-se ao isolamento e à caracterização morfológica. A análise estatística dos parâmetros morfológicos deu origem a um dendrograma de similaridade. Os isolados foram divididos em 17 grupos culturais, a maioria deles diferentes das estirpes referência utilizadas. Tempo de crescimento rápido e metabolismo ácido no meio de cultivo foram as características mais comuns entre os isolados. Ocorreu relação entre agrupamento e origem dos isolados, sendo os isolados pertencentes aos grupos I, J, K, L e M comuns às três espécies. Palavras -Chave: adubação verde, caracterização morfocultural, FBN Abstract: The adoption of conservation practices contributes to soil fertility recovery, providing a reduction in the use of synthetic fertilizers. Because of the ability to form nodules with a wide range of rhizobia, green manure legumes have been used to improve nutrient cycling and nitrogen availability for plants. In this context, the identification of the native rhizobial population associated with green manures can be a tool to improve the contribution of biological nitrogen fixation in agricultural systems. This study aimed to characterize the morphology of bacteria isolated from nodules of three Crotalaria species cultivated in organic farming areas. After collecting the nodules, we proceeded to the isolation and characterization. Statistical analysis of morphocultural parameters has resulted in a similarity dendrogram. The isolates were divided into 17 cultural groups, most of them different from the reference strains used. Most isolates were characterized as rapid growing and acid producing in culture medium. There was a relationship between morphocultural grouping and source of isolates, and isolates belonging to groups I, J, K, L and M were common to the three plant species.
The strain BR 3267 is a nitrogen-fixing symbiotic bacteria isolated from soil of semi-arid area o... more The strain BR 3267 is a nitrogen-fixing symbiotic bacteria isolated from soil of semi-arid area of Brazilian Northeast using cowpea as the trap plant. This strain is used as commercial inoculant for cowpea and presents high efficient in nitrogen fixation as consequence of its adaptation potential to semi-arid conditions. We report here the draft genome sequence of Bradyrhizobium sp. strain BR 3267, an elite bacterium used as inoculant for cowpea. Whole genome sequencing of BR 3267 using Illumina MiSeq sequencing technology has 55 scaffolds with a total genome size of 7,904,309bp and C+G 63%. Annotation was added by the RAST prokaryotic genome annotation service and has shown 7314 coding sequences and 52 RNA genes.
Resumo. Plantas leguminosas que formam simbioses com bactérias diazotróficas nodulíferas são comu... more Resumo. Plantas leguminosas que formam simbioses com bactérias diazotróficas nodulíferas são comumente utilizadas para adubação verde em alternativa a aplicação de fertilizantes nitrogenados. A elevada produção de biomassa por plantas do gênero Crotalaria, as torna uma das mais utilizadas na adubação verde. O objetivo deste trabalho foi avaliar a eficiência de bactérias isoladas de nódulos de Crotalaria ochroleuca para promover acumulo de biomassa seca em plantas desta espécie. Dez isolados com capacidade de nodular Crotalaria ochroleuca, anteriormente caracterizados foram avaliados. As massas de nódulos , raiz e parte aérea secas foram utilizadas para avaliar o desempenho dos isolados, que foram comparados com um tratamento nitrogenado. Um tratamento com a estirpe de Bradyrhizobium sp. BR 2003 e um tratamento sem inoculação nem adubação foram incluídos. Os isolados P4-4(6), P4-5(3), P4-5(7), P4-5(2) e P4-2(1) mostraram eficiência relativa maior que 100%, comparados ao tratamento nitrogenado para o parâmetro massa da parte aérea seca. O isolado P4-4(6) mostrou maior eficiência para os parâmetros massa de raiz seca, massa da parte aérea seca e massa seca total. Palavras-Chave: diversidade, eficiência simbiótica, adubação verde, crotalaria.
Microvirga vignae is a recently described species of root-nodule bacteria isolated from cowpeas g... more Microvirga vignae is a recently described species of root-nodule bacteria isolated from cowpeas grown in a Brazilian semiarid region. We report here the 6.4-Mb draft genome sequence and annotation of M. vignae type strain BR 3299. This genome information may help to understand the mechanisms underlying the ability of the organism to grow under drought and high-temperatures conditions.
The use of peanut as a trap-plant for obtaining rhizobia may result in a high diversity of effici... more The use of peanut as a trap-plant for obtaining rhizobia may result in a high diversity of efficient isolates. This study aimed to evaluate the diversity and symbiotic efficiency of peanut rhizobia from the Southeastern region of Brazil. The bacteria were isolated from nodules of two genotypes in soils from the States of São Paulo and Rio de Janeiro, Brazil. The bacteria were authenticated and evaluated regarding to their symbiotic capacity. The rhizobial diversity was evaluated through their culture characteristics on yeast mannitol agar (YMA) culture media and by polymerase chain reaction Box- (PCR). Two selected isolates were characterized phenotypically regarding their capacity to solubilize phosphate, to grow on media with different concentrations of NaCI, pH's and incubation temperatures. For these the 16S rRNA gene sequencing and symbiotic efficiency using non-autoclaved soils were conducted. The majority of the obtained isolates showed rapid growth and acidified the cult...
Objetivando verificar a diversidade de rizóbio associado a cunhã, foi montado um experimento para... more Objetivando verificar a diversidade de rizóbio associado a cunhã, foi montado um experimento para captura, isolamento e caracterização de isolados. Sementes de cunhã foram cultivadas em amostras de NEOSSOLO FLÚVICO e aos 45 dias a planta foram coletadas e os nódulos destacados da raiz e armazenados para posterior isolamento e caracterização em meio YMA (Yeast malt agar). As 63 estirpes de rizóbio, que foram isoladas e caracterizadas se agruparam em 14 grupos morfológicos, sendo os grupos um e quatro os que tiveram maior números de isolados. O seguinte trabalho nos mostrou que a cunhã é nodulada por uma alta diversidade de rizóbio analisada pelo perfil morfológico.
The biodiversity of rhizobium in soils of the São Francisco Valley is unknown and can be studied ... more The biodiversity of rhizobium in soils of the São Francisco Valley is unknown and can be studied using cowpea as trap plants. The objective of this study was to verify the diversity of diazotrophic bacteria that nodulate cowpea in soils of the lower half of the São Francisco River Valley ...
INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 2014
Microvirga vignae sp. nov., a root nodule symbiotic bacterium isolated from cowpea grown in semi-... more Microvirga vignae sp. nov., a root nodule symbiotic bacterium isolated from cowpea grown in semi-arid Brazil 16S rRNA gene sequence analysis of eight strains (BR 3299 T , BR 3296, BR 10192, BR 10193, BR 10194, BR 10195, BR 10196 and BR 10197) isolated from nodules of cowpea collected from a semi-arid region of Brazil showed 97 % similarity to sequences of recently described rhizobial species of the genus Microvirga. Phylogenetic analyses of four housekeeping genes (gyrB, recA, dnaK and rpoB), DNA-DNA relatedness and AFLP further indicated that these strains belong to a novel species within the genus Microvirga. Our data support the hypothesis that genes related to nitrogen fixation were obtained via horizontal gene transfer, as sequences of nifH genes were very similar to those found in members of the genera Rhizobium and Mesorhizobium, which are not immediate relatives of the genus Microvirga, as shown by 16S rRNA gene sequence analysis. Phenotypic traits, such as host range and carbon utilization, differentiate the novel strains from the most closely related species, Microvirga lotononidis, Microvirga zambiensis and Microvirga lupini. Therefore, these symbiotic nitrogen-fixing bacteria are proposed to be representatives of a novel species, for which the name Microvirga vignae sp. nov. is suggested. The type strain is BR3299 T (5HAMBI 3457 T ).
Brazilian sugarcane has been shown to obtain part of its nitrogen via biological nitrogen fixatio... more Brazilian sugarcane has been shown to obtain part of its nitrogen via biological nitrogen fixation (BNF). Recent reports, based on the culture independent sequencing of bacterial nifH complementary DNA (cDNA) from sugarcane tissues, have suggested that members of the Bradyrhizobium genus could play a role in sugarcane-associated BNF. Here we report on the isolation of Bradyrhizobium spp. isolates and a few other species from roots of sugarcane cultivar RB867515 by two cultivation strategies: direct isolation on culture media and capture of Bradyrhizobium spp. using the promiscuous legume Vigna unguiculata as trap-plant. Both strategies permitted the isolation of genetically diverse Bradyrhizobium spp. isolates, as concluded from enterobacterial repetitive intergenic consensus polymerase chain reaction (PCR) fingerprinting and 16S ribosomal RNA, nifH and nodC sequence analyses. Several isolates presented nifH phylotypes highly similar to nifH cDNA phylotypes detected in fieldgrown sugarcane by a culture-independent approach. Four isolates obtained by direct plate cultivation were unable to nodulate V. unguiculata and, based on PCR analysis, lacked a nodC gene homologue. Acetylene reduction assay showed in vitro nitrogenase activity for some Bradyrhizobium spp. isolates, suggesting that these bacteria do not require a nodule environment for BNF. Therefore, this study brings further evidence that Bradyrhizobium spp. may play a role in sugarcane-associated BNF under field conditions.
Resumo: A adoção de práticas conservacionistas contribui para a recuperação da fertilidade dos so... more Resumo: A adoção de práticas conservacionistas contribui para a recuperação da fertilidade dos solos, proporcionando uma redução do uso de fertilizantes sintéticos. Devido a capacidade de formar nódulos com ampla faixa de rizóbio, tem-se utilizado a adubação verde com leguminosas para ciclagem de nutrientes e disponibilização de nitrogênio para as plantas. Nesse contexto, a identificação da população nativa de rizóbio associada aos adubos verdes pode ser um instrumento para melhorar a contribuição da fixação biológica de nitrogênio nos sistemas agrícolas. O trabalho objetivou caracterizar morfologicamente bactérias isoladas de nódulos de três espécies de Crotalaria, oriundas de área de cultivo orgânico. Após a coleta dos nódulos, procedeu-se ao isolamento e à caracterização morfológica. A análise estatística dos parâmetros morfológicos deu origem a um dendrograma de similaridade. Os isolados foram divididos em 17 grupos culturais, a maioria deles diferentes das estirpes referência utilizadas. Tempo de crescimento rápido e metabolismo ácido no meio de cultivo foram as características mais comuns entre os isolados. Ocorreu relação entre agrupamento e origem dos isolados, sendo os isolados pertencentes aos grupos I, J, K, L e M comuns às três espécies. Palavras -Chave: adubação verde, caracterização morfocultural, FBN Abstract: The adoption of conservation practices contributes to soil fertility recovery, providing a reduction in the use of synthetic fertilizers. Because of the ability to form nodules with a wide range of rhizobia, green manure legumes have been used to improve nutrient cycling and nitrogen availability for plants. In this context, the identification of the native rhizobial population associated with green manures can be a tool to improve the contribution of biological nitrogen fixation in agricultural systems. This study aimed to characterize the morphology of bacteria isolated from nodules of three Crotalaria species cultivated in organic farming areas. After collecting the nodules, we proceeded to the isolation and characterization. Statistical analysis of morphocultural parameters has resulted in a similarity dendrogram. The isolates were divided into 17 cultural groups, most of them different from the reference strains used. Most isolates were characterized as rapid growing and acid producing in culture medium. There was a relationship between morphocultural grouping and source of isolates, and isolates belonging to groups I, J, K, L and M were common to the three plant species.
The strain BR 3267 is a nitrogen-fixing symbiotic bacteria isolated from soil of semi-arid area o... more The strain BR 3267 is a nitrogen-fixing symbiotic bacteria isolated from soil of semi-arid area of Brazilian Northeast using cowpea as the trap plant. This strain is used as commercial inoculant for cowpea and presents high efficient in nitrogen fixation as consequence of its adaptation potential to semi-arid conditions. We report here the draft genome sequence of Bradyrhizobium sp. strain BR 3267, an elite bacterium used as inoculant for cowpea. Whole genome sequencing of BR 3267 using Illumina MiSeq sequencing technology has 55 scaffolds with a total genome size of 7,904,309bp and C+G 63%. Annotation was added by the RAST prokaryotic genome annotation service and has shown 7314 coding sequences and 52 RNA genes.
Resumo. Plantas leguminosas que formam simbioses com bactérias diazotróficas nodulíferas são comu... more Resumo. Plantas leguminosas que formam simbioses com bactérias diazotróficas nodulíferas são comumente utilizadas para adubação verde em alternativa a aplicação de fertilizantes nitrogenados. A elevada produção de biomassa por plantas do gênero Crotalaria, as torna uma das mais utilizadas na adubação verde. O objetivo deste trabalho foi avaliar a eficiência de bactérias isoladas de nódulos de Crotalaria ochroleuca para promover acumulo de biomassa seca em plantas desta espécie. Dez isolados com capacidade de nodular Crotalaria ochroleuca, anteriormente caracterizados foram avaliados. As massas de nódulos , raiz e parte aérea secas foram utilizadas para avaliar o desempenho dos isolados, que foram comparados com um tratamento nitrogenado. Um tratamento com a estirpe de Bradyrhizobium sp. BR 2003 e um tratamento sem inoculação nem adubação foram incluídos. Os isolados P4-4(6), P4-5(3), P4-5(7), P4-5(2) e P4-2(1) mostraram eficiência relativa maior que 100%, comparados ao tratamento nitrogenado para o parâmetro massa da parte aérea seca. O isolado P4-4(6) mostrou maior eficiência para os parâmetros massa de raiz seca, massa da parte aérea seca e massa seca total. Palavras-Chave: diversidade, eficiência simbiótica, adubação verde, crotalaria.
Microvirga vignae is a recently described species of root-nodule bacteria isolated from cowpeas g... more Microvirga vignae is a recently described species of root-nodule bacteria isolated from cowpeas grown in a Brazilian semiarid region. We report here the 6.4-Mb draft genome sequence and annotation of M. vignae type strain BR 3299. This genome information may help to understand the mechanisms underlying the ability of the organism to grow under drought and high-temperatures conditions.
The use of peanut as a trap-plant for obtaining rhizobia may result in a high diversity of effici... more The use of peanut as a trap-plant for obtaining rhizobia may result in a high diversity of efficient isolates. This study aimed to evaluate the diversity and symbiotic efficiency of peanut rhizobia from the Southeastern region of Brazil. The bacteria were isolated from nodules of two genotypes in soils from the States of São Paulo and Rio de Janeiro, Brazil. The bacteria were authenticated and evaluated regarding to their symbiotic capacity. The rhizobial diversity was evaluated through their culture characteristics on yeast mannitol agar (YMA) culture media and by polymerase chain reaction Box- (PCR). Two selected isolates were characterized phenotypically regarding their capacity to solubilize phosphate, to grow on media with different concentrations of NaCI, pH's and incubation temperatures. For these the 16S rRNA gene sequencing and symbiotic efficiency using non-autoclaved soils were conducted. The majority of the obtained isolates showed rapid growth and acidified the cult...
Objetivando verificar a diversidade de rizóbio associado a cunhã, foi montado um experimento para... more Objetivando verificar a diversidade de rizóbio associado a cunhã, foi montado um experimento para captura, isolamento e caracterização de isolados. Sementes de cunhã foram cultivadas em amostras de NEOSSOLO FLÚVICO e aos 45 dias a planta foram coletadas e os nódulos destacados da raiz e armazenados para posterior isolamento e caracterização em meio YMA (Yeast malt agar). As 63 estirpes de rizóbio, que foram isoladas e caracterizadas se agruparam em 14 grupos morfológicos, sendo os grupos um e quatro os que tiveram maior números de isolados. O seguinte trabalho nos mostrou que a cunhã é nodulada por uma alta diversidade de rizóbio analisada pelo perfil morfológico.
The biodiversity of rhizobium in soils of the São Francisco Valley is unknown and can be studied ... more The biodiversity of rhizobium in soils of the São Francisco Valley is unknown and can be studied using cowpea as trap plants. The objective of this study was to verify the diversity of diazotrophic bacteria that nodulate cowpea in soils of the lower half of the São Francisco River Valley ...
INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 2014
Microvirga vignae sp. nov., a root nodule symbiotic bacterium isolated from cowpea grown in semi-... more Microvirga vignae sp. nov., a root nodule symbiotic bacterium isolated from cowpea grown in semi-arid Brazil 16S rRNA gene sequence analysis of eight strains (BR 3299 T , BR 3296, BR 10192, BR 10193, BR 10194, BR 10195, BR 10196 and BR 10197) isolated from nodules of cowpea collected from a semi-arid region of Brazil showed 97 % similarity to sequences of recently described rhizobial species of the genus Microvirga. Phylogenetic analyses of four housekeeping genes (gyrB, recA, dnaK and rpoB), DNA-DNA relatedness and AFLP further indicated that these strains belong to a novel species within the genus Microvirga. Our data support the hypothesis that genes related to nitrogen fixation were obtained via horizontal gene transfer, as sequences of nifH genes were very similar to those found in members of the genera Rhizobium and Mesorhizobium, which are not immediate relatives of the genus Microvirga, as shown by 16S rRNA gene sequence analysis. Phenotypic traits, such as host range and carbon utilization, differentiate the novel strains from the most closely related species, Microvirga lotononidis, Microvirga zambiensis and Microvirga lupini. Therefore, these symbiotic nitrogen-fixing bacteria are proposed to be representatives of a novel species, for which the name Microvirga vignae sp. nov. is suggested. The type strain is BR3299 T (5HAMBI 3457 T ).
Brazilian sugarcane has been shown to obtain part of its nitrogen via biological nitrogen fixatio... more Brazilian sugarcane has been shown to obtain part of its nitrogen via biological nitrogen fixation (BNF). Recent reports, based on the culture independent sequencing of bacterial nifH complementary DNA (cDNA) from sugarcane tissues, have suggested that members of the Bradyrhizobium genus could play a role in sugarcane-associated BNF. Here we report on the isolation of Bradyrhizobium spp. isolates and a few other species from roots of sugarcane cultivar RB867515 by two cultivation strategies: direct isolation on culture media and capture of Bradyrhizobium spp. using the promiscuous legume Vigna unguiculata as trap-plant. Both strategies permitted the isolation of genetically diverse Bradyrhizobium spp. isolates, as concluded from enterobacterial repetitive intergenic consensus polymerase chain reaction (PCR) fingerprinting and 16S ribosomal RNA, nifH and nodC sequence analyses. Several isolates presented nifH phylotypes highly similar to nifH cDNA phylotypes detected in fieldgrown sugarcane by a culture-independent approach. Four isolates obtained by direct plate cultivation were unable to nodulate V. unguiculata and, based on PCR analysis, lacked a nodC gene homologue. Acetylene reduction assay showed in vitro nitrogenase activity for some Bradyrhizobium spp. isolates, suggesting that these bacteria do not require a nodule environment for BNF. Therefore, this study brings further evidence that Bradyrhizobium spp. may play a role in sugarcane-associated BNF under field conditions.
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