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Provedor de dados:  Rev. Bras. Ciênc. Solo
País:  Brazil
Título:  Exopolysaccharides produced by the symbiotic nitrogen-fixing bacteria of leguminosae
Autores:  Bomfeti,Cleide Aparecida
Florentino,Ligiane Aparecida
Guimarães,Ana Paula
Cardoso,Patrícia Gomes
Guerreiro,Mário César
Moreira,Fatima Maria de Souza
Data:  2011-06-01
Ano:  2011
Palavras-chave:  Exopolysaccharides
Nodules
Environmental stress
Soil aggregation
Rhizobia
Resumo:  The 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.
Tipo:  Info:eu-repo/semantics/article
Idioma:  Inglês
Identificador:  http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832011000300001
Editor:  Sociedade Brasileira de Ciência do Solo
Relação:  10.1590/S0100-06832011000300001
Formato:  text/html
Fonte:  Revista Brasileira de Ciência do Solo v.35 n.3 2011
Direitos:  info:eu-repo/semantics/openAccess
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