Abstract The main objective of this study was to optimize the fermentation process using Serratia sp. BR13816, a bacterial isolate from Amazonian soil, and to evaluate the formation of nanoemulsions. Submerged fermentation was carried out with different carbon and nitrogen sources. Based on the emulsification index and surface tension results, we selected a hydrophobic (corn oil) and a hydrophilic (glycerol) carbon source, and a nitrogen one (urea). For fermentation using corn oil/urea greater emulsification indexes and lower surface tensions were verified at pH 8, 25 °C, and 48 h, whereas for glycerol/urea-supplemented medium the best conditions were attained at pH 7, 30 °C, and 96 h. These pre-selected factors (pH, temperature, and time) were used in a central composite rotatable design (CCRD) for an additional fermentation optimization of the two carbon/nitrogen mediums, corn oil/urea and glycerol/urea. The two best nutritional systems based on corn oil/urea and glycerol/urea were selected using a central composite rotatable design (CCRD). The mathematical models using the response surface methodology showed adequate adjustment. The best run of the experimental design for corn oil/urea (6.00% /0.60%) and glycerol/urea (3.00% /1.40%) systems presented surface tension values of 35.70 mN/m and 37.10 mN/m, respectively. The nanoemulsions produced by a low-energy method presented average sizes by dynamic light scattering varying from 453.1 nm to 667.3 nm when 0.1% of the oil was employed. Therefore, Serratia sp. BR13816 showed promising biosurfactant-producing potential for future industrial applications. sp BR soil sources results glycerol (glycerol source urea. urea . (urea) oilurea 8 2 C °C 4 h glycerol/ureasupplemented glycerolureasupplemented supplemented 7 3 9 preselected pre pH, (pH temperature time CCRD (CCRD carbonnitrogen mediums glycerolurea CCRD. adjustment 6.00% 600 6 00 (6.00 /0.60% 060 0 60 3.00% 300 (3.00 /1.40% 140 1 40 3570 35 70 35.7 mNm mN m 3710 37 10 37.1 respectively lowenergy low energy 4531 453 453. 6673 667 667. 01 0.1 employed Therefore BR1381 biosurfactantproducing biosurfactant producing applications (urea ureasupplemented 6.00 (6.0 /0.60 06 3.00 (3.0 /1.40 14 357 35. 371 37. 45 66 0. BR138 6.0 (6. /0.6 3.0 (3. /1.4 BR13 6. (6 /0. 3. (3 /1. BR1 ( /0 /1 /

Resumo: O objetivo deste trabalho foi avaliar a resposta da cultivar BRS Tumucumaque de feijão-caupi (Vigna unguiculata) à calagem e à adubação com fósforo e potássio na ausência de inoculação ou adubação nitrogenada, bem como à inoculação com estirpes selecionadas de Bradyrhizobium, em área de floresta de terra firme no estado do Amapá, na Amazônia Oriental, Brasil. Foram conduzidos sete experimentos em condição de campo, para avaliar seis níveis de calcário, quatro de fósforo e quatro de potássio, além da inoculação com quatro estirpes de Bradyrhizobium. Foram avaliados teores foliares de nitrogênio, massa seca de vagens e de grãos por planta, produtividade de grãos, e pH, Al+3 e Ca+2 + Mg+2 no solo. Os dados obtidos foram submetidos à análise de variância, à análise de regressão ou a teste para comparação de médias. O solo apresentou alto poder tampão, mas a calagem reduziu as suas limitações químicas. Os teores foliares de nitrogênio se correlacionaram com a produtividade de grãos de feijão-caupi. No entanto, não há efeito da interação entre os níveis de potássio e fósforo sobre a produtividade de grãos. Além disso, a produtividade de grãos não é influenciada pela calagem e pela adubação com potássio, mas aumenta com a adubação com fósforo. A inoculação com as estirpes UFLA 3-84 e INPA 03-11B promove maior rendimento de grãos do que a com as BR 3262 e BR 3267, bem como produtividade de grãos semelhante à do controle sem inoculação.

Abstract: The objective of this work was to evaluate the response of the BRS Tumucumaque cowpea (Vigna unguiculata) cultivar to liming and to phosphorus and potassium fertilization in the absence of inoculation or nitrogen fertilization, as well as to inoculation with selected Bradyrhizobium strains, in an upland forest area in the state of Amapá, eastern Amazon, Brazil. Seven experiments were conducted in field conditions, in order to evaluate six limestone, four phosphorus, and four potassium rates, besides the inoculation with four Bradyrhizobium strains. Leaf nitrogen concentrations, pod and grain dry mass per plant, grain yield, and soil pH, Al+3, and Ca+2 + Mg+2 were evaluated. The obtained data were subjected to the analysis of variance, to the regression analysis, or to test to compare means. The soil presented a high buffer power, but liming reduced its chemical limitations. Leaf nitrogen concentrations were correlated to cowpea grain yield. However, there is no effect of the interaction between potassium and phosphorus rates on grain yield. In addition, grain yield is not influenced by liming and potassium fertilization, but is increased by phosphorus fertilization. Inoculation with the UFLA 3-84 and INPA 03-11B strains promotes a greater grain yield than that with BR 3262 and BR 3267, as well as a similar grain yield to that of the control without inoculation.

Abstract Little is known regarding how the increased diversity of nitrogen-fixing bacteria contributes to the productivity and diversity of plants in complex communities. However, some authors have shown that the presence of a diverse group of nodulating bacteria is required for different plant species to coexist. A better understanding of the plant symbiotic organism diversity role in natural ecosystems can be extremely useful to define recovery strategies of environments that were degraded by human activities. This study used ARDRA, BOX-PCR fingerprinting and sequencing of the 16S rDNA gene to assess the diversity of root nodule nitrogen-fixing bacteria in former bauxite mining areas that were replanted in 1981, 1985, 1993, 1998, 2004 and 2006 and in a native forest. Among the 12 isolates for which the 16S rDNA gene was partially sequenced, eight, three and one isolate(s) presented similarity with sequences of the genera Bradyrhizobium, Rhizobium and Mesorhizobium, respectively. The richness, Shannon and evenness indices were the highest in the area that was replanted the earliest (1981) and the lowest in the area that was replanted most recently (2006).

Entre os gêneros que exibem nodulação caulinar Aeschynomene e Discolobium são encontrados no Pantanal Mato-grossense (áreas inundáveis no Estado do Mato Grosso, Brasil). Isolados obtidos de nódulos de caule e raiz de D. pulchellum, D. psoraleaefolium, D. leptophyllum and A. fluminensis foram coletados em vários pontos no Pantanal de Poconé e caracterizados fenotípica e genotipicamente, pela análise de restrição do gene 16S rDNA. Dos 282 isolados obtidos de nódulos de caule e raiz 84,3% alcalinizaram o meio YMA e 74,1% apresentaram crescimento lento. Não se observou diferença fenotípica nem genotípica entre as populações de rizóbio isoladas de nódulos radiculares ou caulinares das espécies de Discolobium e de A. fluminensis. Entre os isolados obtidos da espécie Discolobium pulchellum obteve-se um grupo que não agrupou similaridade com nenhuma das estirpes de referência utilizadas e a maior parte dos isolados analisados pelo PCR\RFLP apresentou similaridade com o gênero Bradyrhizobium.

Among the genera that exhibit stem nodulation, Aeschynomene and Discolobium are found in the Pantanal Mato-grossense (wetlands in the state of Mato Grosso, Brazil). Isolates obtained from the stem and root nodules of D. pulchellum, D. psoraleaefolium, D. leptophyllum and A. fluminensis were collected from various locations in the Pantanal de Poconé sub-region and phenotypically characterized and genotyped by restriction analysis of the 16S rDNA gene. Of the 282 isolates obtained from the stem and root nodules, 84.3% alkalized YMA media and 74.1% showed slow growth. No differences in either the phenotype or the genotype among the rhizobial populations isolated from the root or stem nodules of the species Discolobium and A. fluminensis were observed. Among the isolates obtained from D. pulchellum, there was a group that was not similar to any of the reference strains used, and most of the isolates analyzed by PCR-RFLP were similar to the genus Bradyrhizobium.

The aim of this study was to characterize rhizobial isolates from Cratylia mollis Mart. ex Benth, Calliandra depauperata Benth. and Mimosa tenuiflora (Willd.) Poir. by means of rhizobial colonies morphology and restriction analysis of the 16S ribosomal gene (16S rDNA-ARDRA). Nodules were collected in the field and from plants cultivated in a greenhouse experiment using Caatinga soil samples. Sixty seven isolates were described by morphological analysis. Forty seven representative isolates were used for ARDRA analysis using seven restriction enzymes. We observed high diversity of both slow and fast-growing rhizobia that formed three morpho-physiological clusters. A few fast-growing isolates formed a group of strains of the Bradyrhizobium type; however, most of them diverged from the B. japonicum and B. elkanii species. Cratylia mollis nodule isolates were the most diverse, while all Mimosa tenuiflora isolates displayed fast growth with no pH change and were clustered into groups bearing 100% similarity, according to ARDRA results.

Em função das características nutricionais e de rusticidade, o feijão-caupi tornou-se importante fonte de proteína na Região Nordeste do Brasil. O caupi se beneficia da fixação biológica de nitrogênio e pode receber parte do nitrogênio necessário para a cultura via simbiose, o que reduz os custos de produção. Um experimento em condições de casa-de-vegetação foi conduzido com o objetivo de avaliar a diversidade de isolados de rizóbio de nódulos de caupi em solos do Estado do Rio Grande do Norte. Os nódulos foram coletados de raízes de Vigna unguiculata (L.) Walp., utilizada como planta-isca, sendo obtidos 304 isolados com características típicas de rizóbio. Embora todos os isolados tenham apresentado crescimento rápido e ácido em meio de cultivo, os isolados apresentaram elevada diversidade morfológica e foram agrupados em 18 grupos morfológicos. Não foi observada diferença de diversidade de isolados de rizóbio entre as diferentes amostras de solo analisadas.

As a result of it nutritional and rustic characteristics, cowpea has become an important source protein in the Northeast region of Brazil. Cowpea may benefit from biological nitrogen fixation and can receive part of the nitrogen needed for culture from symbiosis, which reduces the cost of production. An experiment in greenhouse conditions was carried out in order to assess the diversity of rhizobia isolates of the nodules of cowpea, in soils from Rio Grande do Norte State. The nodules were obtained from roots of Vigna unguiculata (L.) Walp., a species used as trap plant; 304 isolates with typical rhizobial features were obtained. Although all isolates showed rapid and acid growth in the medium, the isolates showed high morphological diversity, forming 18 clusters. No diversity differences of rhizobial isolates were observed among the different soil samples studied.

O objetivo deste trabalho foi avaliar a variabilidade genética entre 29 acessos de amendoim (Arachis hypogaea L.), por meio de marcadores moleculares randômicos (DNA polimórfico amplificado ao acaso - RAPD). O ensaio molecular foi realizado com 31 iniciadores, dos quais 12 (39%) mostraram polimorfismo. Observou-se o total de 145 fragmentos amplificados, dos quais 35 (24%) foram polimórficos, com média de 4,67 fragmentos por iniciador e 1,13 fragmento polimórfico por iniciador. Pelo dendrograma, observou-se que os acessos foram separados em dois grupos com 89% de similaridade. Esta distribuição mostra a variabilidade existente entre os acessos das diferentes variedades botânicas, uma vez que acessos da subespécie fastigiata estão presentes nos dois grupos principais, e os acessos da subespécie hypogaea estão distribuídos pelos subgrupos A e B do grupo II do dendograma.

The objective of this study was to evaluate the genetic variability among 29 accessions of peanut (Arachis hypogaea L.) by means of random molecular markers (random amplified polimorphic DNA - RAPD). The molecular assay was performed with 31 primers, of which 12 (39%) revealed polymorphism. It was observed a total of 145 amplified fragments, of which 35 (24%) were polymorphic, with an average of 4.67 fragments by primer and 1.13 polymorphic fragment by primer. It was observed through the dendrogram that the accessions were separated into two groups with 89% of similarity. This distribution shows the variability among the accessions of the different botanical varieties, since the accessions of subspecie fastigiata are present in two principal groups, and the accessions of subspecie hypogaea are distributed in subgroups A and B from dendrogram group II.