Crescimento de Bradyrhizobium elkanii estirpe Br 29 em meios de cultivo com diferentes valores de pH inicial

Barberi, Alexandre; Moreira, F. M. S.; Florentino, Ligiane Aparecida; Rodrigues, Maria Isabel

doi:10.1590/s1413-70542004000200021

Cited by 10 publications

(8 citation statements)

References 17 publications

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“…The strains BR 29 and SEMIA 587 of Bradyrhizobium elkanii, recommended as soybean inoculants, produce greater amount of EPS when grown in acidic conditions than when cultivated at a neutral pH (Barberi et al 2004;Miguel & Moreira, 2001). The same trend of increased production of EPS under acidic conditions and with limited Ca 2+ was observed in the strain USDA 3187 of Bradyrhizobium sp.…”

Section: Exopolysaccharides In the Process Of Rhizobia Adaptation To mentioning

confidence: 59%

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Exopolysaccharides produced by the symbiotic nitrogen-fixing bacteria of leguminosae

Bomfeti

Florentino

Guimarães³

et al. 2011

Rev. Bras. Ciênc. Solo

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SUMMARYThe process of biological nitrogen fixation (BNF), performed by symbiotic nitrogen fixing bacteria with legume species, commonly known as α and β rhizobia, provides high sustainability for the ecosystems. Its management as a biotechnology is well succeeded for improving crop yields. A remarkable example of this success is the inoculation of Brazilian soybeans with Bradyrhizobium strains. Rhizobia produce a wide diversity of chemical structures of exopolysaccharides (EPS). Although the role of EPS is relatively well studied in the process of BNF, their economic and environmental potential is not yet explored. These EPS are mostly species-specific heteropolysaccharides, which can vary according to the composition of sugars, their linkages in a single subunit, the repeating unit size and the degree of polymerization. Studies have showed that the EPS produced by rhizobia play an important role in the invasion process, infection threads formation, bacteroid and nodule development and plant defense response. These EPS also confer protection to these bacteria when exposed to environmental stresses. In general, strains of rhizobia that produce greater amounts of EPS are more tolerant to adverse conditions when compared with strains that produce less. Moreover, it is known that the EPS produced by microorganisms are widely used in various industrial activities. These compounds, also called biopolymers, provide a valid alternative for the commonly used in food industry through the development of products with identical properties or with better rheological characteristics, which can be used for new applications. The microbial EPS are also able to increase the adhesion of soil particles favoring the mechanical stability of aggregates, increasing levels of water retention and air flows in this environment. Due to the importance of EPS, in this review we discuss the role of these compounds in the process of BNF, in the adaptation of rhizobia to environmental stresses and in the process of soil aggregation. The possible applications of these biopolymers in industry are also discussed.Index terms: Exopolysaccharides, nodules, environmental stress, soil aggregation, rhizobia. RESUMO: EXOPOLISSACARÍDEOS PRODUZIDOS POR BACTÉRIAS FIXADORAS DE NITROGÊNIO SIMBIÓTICAS DE LEGUMINOSAE O processo de fixação biológica de nitrogênio (FBN), realizado por bactérias fixadoras de

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Section: Exopolysaccharides In the Process Of Rhizobia Adaptation To mentioning

confidence: 59%

“…In these cases, the increased EPS production is considered an adaptation mechanism of these bacteria (Barberi et al, 2004;Macció et al, 2002). Thus, the EPS synthesis by rhizobia can also be regulated by the culture conditions.…”

Section: Exopolysaccharides In the Process Of Rhizobia Adaptation To mentioning

confidence: 99%

Exopolysaccharides produced by the symbiotic nitrogen-fixing bacteria of leguminosae

Bomfeti

Florentino

Guimarães³

et al. 2011

Rev. Bras. Ciênc. Solo

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“…Reports published on the production of exopolymers show that the hydroaromatic acids shikimate and quinate, which may be available as carbon sources in the soil, supported production of only low levels of acidic exopolysaccharide by B. elkanii and B. japonicum [23]. Strains BR 29 and SEMIA 587 of B. elkanii produce greater amounts of EPS when grown in acidic conditions than when cultivated at a neutral pH [24]. However, previous results in our laboratory demonstrated that the culture medium of B. elkanii SEMIA 587 and mutant strains was unable to precipitate EPS using alcohol, although we observed biopolymers in the supernatant.…”

Section: Introductionmentioning

confidence: 99%

Emulsification Properties of Bioemulsifiers Produced by Wild-Type and Mutant Bradyrhizobium elkanii Strains

Lopes¹

2014

J Bioremed Biodeg

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The use of biosurfactant is a promising alternative over the chemical surfactant as they are better biodegradable and do not pollute the environment. To date, there is little information on the biosurfactant producing microorganisms belonging to different Rhizobium and Bradyrhizobium species. In this study, the emulsifying properties of both culture media and a substantially cell-free medium from bacterial cell cultures in which B. elkanii SEMIA 587 or mutant strains cultivated in defined media supplemented with sucrose were determined by measuring the emulsifying activity, which determined the ability of biosurfactant in forming oil-water emulsion, and emulsifying index (E 24 ), which determined the capacity of surfactant in forming emulsions on different hydrophobic substrates (soybean oil, sunflower oil or diesel oil). The performance of strains as bio emulsifier were very contrasting as shown by their specific emulsification indexes with different substrates, beginning at 24 hours. Regarding emulsifying index for cells, best result of E 24 was obtained by using sunflower oil for wild type and mutants with exception for 587::TnphoA31 that witch got better results in soybean oil. However, analysing using cell-free medium have shown higher E 24 values mostly in soybean oil except for 587::TnphoA31 and 587::TnphoA50 which have performed better in diesel oil. This finding indicates a probable production of bioemulsificants that adhere to the cell wall of this bacterium and are extracellular. The same E 24 value (79.17%) was observed in the case of soybean oil with culture medium from both the wild-type and the mutant strain 587::TnphoA50. The emulsification capacity was very sensitive to the temperature, pH and NaCl concentration changes. These results demonstrate that the Bradyrhizobium strains could be attractive for use in biosurfactants applications, these products is great due to growing demand for biodegradable and environmentally friendly analogues for synthetic chemicals. Journal of Bior emediation & Biodegradation

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“…Para Roraima, Zilli et al (2006;2011) sugerem as cepas BR 3267, BR 3262 e SEMIA 587 para inoculação de feijão-caupi, capazes de proporcionar rendimentos semelhantes à aplicação de 50 kg ha -1 de N no plantio ou 80 kg ha -1 de N parcelada em 2 vezes. No entanto, pouco tem sido investigado sobre o comportamento da estirpe em condições edáficas diversas, uma vez que há registro de efeitos do pH e presença de Al 3+ (BARBERI et al, 2004), disponibilidade de nutrientes, temperatura e umidade do solo (MARTINS et al, 2003) na eficiência da FBN.…”

Section: Introductionunclassified

Inoculação com Bradyrhizobium e adubação nitrogenada em feijão-caupi cultivado em diferentes solos

Santos¹,

Uchôa²,

Melo³

et al. 2014

Agro@mbiente

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Resumo -A fixação biológica do nitrogênio (FBN) pode ser limitada pela alta disponibilidade de nitrogênio (N). A fração argila e o teor de matéria orgânica do solo controlam a disponibilidade do N, sendo possível que esses atributos venham a interferir na fixação simbiótica em solos adubados com N. Com base nesse pressuposto, objetivou-se com o presente trabalho avaliar o efeito da adubação nitrogenada na fixação biológica do N em feijão-caupi cultivado em cinco solos, com ampla variação nos seus atributos físicos, químicos e mineralógicos, representativos das áreas de cultivo da Savana de Roraima. O experimento foi conduzido em casa de vegetação, utilizando-se vasos de polietileno rígido com 5 dm 3 de solo coletado na camada de 0-0,20 m. Empregou-se o delineamento experimental em blocos casualizados em esquema fatorial (5x5), sendo 5 classes de solos (LAdx; LVd; PAdx; PVAd; RYve), 4 doses de nitrogênio (0; 20; 40; 80 kg ha -1 ) em plantas inoculadas e uma testemunha (sem inoculação e sem adubação nitrogenada), com 4 repetições. Utilizaram-se sementes da cultivar de feijão-caupi BRS Guariba inoculadas com a estirpe de Bradyrhizobium BR 3262. Avaliaram-se: número, tamanho e massa da vagem, massa seca da raiz, número de nódulos e massa seca de nódulos. A FBN proporcionou aumento nas variáveis estudadas em todos os solos. As doses de N em plantas inoculadas proporcionaram incrementos significativos que variaram entre as classes de solo, sendo de 3 a 18% nos componentes de produção e de 8 a 70% para as demais variáveis. A adubação nitrogenada afeta a nodulação em feijão-caupi, sendo restritiva em alguns solos. Palavras-chave -Classes de solos. Fixação biológica de nitrogênio. Fertilidade do solo. Vigna unguiculata (L.) Walp.Abstract -Biological nitrogen fixation (BNF) can be limited by the high availability of nitrogen (N). The soil clay fraction and organic matter content control the availability of N, and it is possible that these attributes affect the symbiotic fixation in soils fertilized with N. Based in that assumption, the objective with this study was to evaluate the effect of N fertilization on biological fixation in cowpea grown in five soils, with wide variation in their physical, chemical and and mineralogical attributes, representative of the growing areas of savannah of Roraima. The experiment was carried out in polyethylene pots in randomized blocks design with factorial arrangement 5x5, 5 soils (LAdx; LVd; PAdx; PVAd; RYve), 4 doses of nitrogen (0, 20, 40, 80 kg ha -1 ) in inoculated plants and a control (without inoculation and nitrogen fertilization), with 4 replications. The seeds of BRS Guariba were inoculated with Bradyrhizobium strain BR 3262. The variables studied were: number, size and mass of the pod, root dry mass, nodule number and dry weight of nodules. The BNF provided an increase in the variables studied in all soils. N levels in inoculated plants provided significant increases varying between soil classes, 3-18% for yield components and 8-70% for the other variables. Nitrogen fertiliza...

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Crescimento de Bradyrhizobium elkanii estirpe Br 29 em meios de cultivo com diferentes valores de pH inicial

Cited by 10 publications

References 17 publications

Exopolysaccharides produced by the symbiotic nitrogen-fixing bacteria of leguminosae

Exopolysaccharides produced by the symbiotic nitrogen-fixing bacteria of leguminosae

Emulsification Properties of Bioemulsifiers Produced by Wild-Type and Mutant Bradyrhizobium elkanii Strains

Inoculação com Bradyrhizobium e adubação nitrogenada em feijão-caupi cultivado em diferentes solos

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