Métodos de esterilização de sementes de arroz para cultivo monoxênico com bactérias diazotróficas.

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Characterization of Herbaspirillum seropedicae gen. nov., sp. nov., a root-associated nitrogen-fixing bacterium.

During a survey of the occurrence of Azospirillum spp. in cereal roots, we obtained 119 isolates which could not be identified as members of one of the three previously described Azospirillum species. These strains formed a very homogeneous group of N2-fixing, microaerobic, motile, vibrioid, gram-negative rod-shaped organisms which formed a veillike pellicle in semisolid medium similar to that of Azospirillum spp. However, the new isolates differed from Azospirillum spp. by their smaller cell width (0.6 to 0.7 μm), variable flagellation (one to three flagella on one or both poles), moist brownish colonies, and broader pH and oxygen tolerance for nitrogenase activity. Organic acids were the preferred carbon sources, but glucose, galactose, L-arabinose, mannitol, sorbitol, and glycerol were also used. The guanine-plus-cytosine content of the deoxyribonucleic acid was slightly lower than the guanine-plus-cytosine contents of Azospirillum spp. (66 to 67 mol%). Deoxyribonucleic acid hybridization experiments with 17 strains of the group showed 50 to 100% complementarity, while the levels of hybridization with the type strains of Azospirillum brasilense, Azospirillum lipoferum, and Azospirillum amazonense were 23, 15, and 6%, respectively. For these new isolates we propose a new genus, Herbaspirillum (the name refers to the habitat of the organisms, the roots of cereals, which are herbaceous seed-bearing plants). The type species is named Herbaspirillum seropedicae after the place where it was first isolated. The type strain is strain Z67, which has been deposited in the American Type Culture Collection as strain ATCC 3589

Bactérias diazotróficas em abacaxizeiros e bananeiras: técnicas de inoculação e monitoramento.

As bacterias diazotroficas tem sido isoladas de varias culturas, alem de leguminosas e gramineas, que tem importancia economica e social; deplantas de tuberculos como a mandioca foram isoladas bacterias do genero Burkholderia, entre outras(Balota, 1994); ja em plantas de batata-doce tem sido detectadas especies de Azospirillum(Hill et al.,1983) e Acetobacter diazophicus(Paula, 1992). Esta ultima especie também tem sido isolada de plantas de cafe(Jimenez-Salgado et al., 1998); na rizosfera de fruteiras tropicais tem sido isoladas especies de Azospirillum(Subba Rao, 1983; Ghai & Thomas, 1989). Especies deste genero e bacterias diazotroficas do tipo Herbaspirillum e Burkholderia foram tambem isoladas de raizes...bitstream/CNPAT-2010/4782/1/Dc-035.pd

Fixação biológica de nitrogênio: Bactérias fixadoras de nitrogênio de importância para a agricultura tropical.

Diazotrofos de vida livre. Diazotrofos associativos. Endófiticos facultativos. Endofíticos obrigatórios. Diazotrofos simbióticos.bitstream/CNPAB-2010/27316/1/doc091.pd

Ensaio de atividade de B-galactosidase em Gluconacetobacter diazotrophicus para estudos de expressão gênica.

Este Comunicado Técnico mostra a repetitibilidade de ensaios de atividade de ?-galactosidase, que foram padronizados com G. diazotrophicus, ilustrando sua utilidade em estudos de expressão gênica que envolvem fusões com o gene repórter lacZ. Os resultados mostrados neste Comunicado Técnico ilustram que o meio, as condições de cultivo e o ensaio de atividade de ?-galactosidase estabelecidos para G. diazotrophicus são reprodutíveis, e, portanto, válidos, sendo de grande valia para quantificar níveis de expressão gênica nessa importante bactéria constituinte do inoculante para cana-de-açúcar da Embrapa.bitstream/item/42760/1/COT123-09.pd

Indução de substâncias antagônicas produzidas pela bactéria endofítica Gluconacetobacter diazotrophicus por raios ultravioleta.

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Genetic diversity and plant growth promoting traits of diazotrophic bacteria isolated two Pennisetum purpureum Schum. Genotypes grown in the field.

Background and aims Some elephant grass (Pennisetum purpureum) genotypes are able to produce large amounts of biomass and accumulate N derived from BNF when growing in soil with low N levels. However, information about the diazotrophic bacteria colonizing this C4 plant is still very scarce. This study aimed to characterize the plant growth promoting traits of a fraction of culturable diazotrophs colonizing the genotypes CNPGL F06-3 and Cameroon. Methods A total of 204 isolates were obtained from surface sterilized leaves, stems and roots after culturing on five different N-free semisolid media. These were then analyzed by BOX-PCR, and the 16S rRNA and nifH sequences of representative isolates were obtained. The functional ability of the isolates to reduce acetylene, produce indole and to solubilize phosphate was also determined. Results The diazotrophic bacterial population varied from 102 up to 106 bacteria g?1 fresh tissues of both genotypes. The BOX-PCR analysis suggested a trend in the genetic diversity among the 204 diazotrophic strains colonizing the different genotypes and plant tissues. Sequencing of 16S rRNA fragments confirmed the presence of Azospirillum brasilense and Gluconacetobacter diazotrophicus and revealed for the first time the occurrence of G. liquefaciens, G. sacchari, Burkholderia silvatlantica, Klebsiella sp., Enterobacter cloacae and E. oryzae in elephant grass. Interestingly, several nifH sequences from isolates identified as G. liquefaciens and G. sacchari showed homologies with nifH sequences of Enterobacter species. The majority of the isolates (97%) produced indole compounds, 22% solubilized phosphate and 6.4% possessed both characteristics