Produção e comportamento reológico de exopolissacarídeos sintetizados por rizóbios isolados de guandu

Abstract

Resumo -O objetivo deste trabalho foi avaliar a produção e o comportamento reológico de exopolissacarídeos (EPS) produzidos por rizóbios isolados de nódulos de guandu [Cajanus cajan (L.) Production and rheological behavior of exopolysaccharide synthesized by pigeonpea rhizobia isolatesAbstract -The objective of this work was to evaluate the production and the rheological behavior of exopolysaccharides (EPS) produced by pigeonpea [Cajanus cajan (L.) Millsp.] rhizobia isolates, as well as to evaluate the similarity of these isolates through amplified ribosomal DNA restriction analysis technique. The bacteria were cultured in YM liquid media and the EPS were precipited with cold ethanol from culture broth. After that, they were vacuum dried, weighted, stored and resuspended in water to rheological evaluations. The three evaluated isolates showed differences on the production and productivity of EPS, and the isolate 8.1c stood out, with higher relative efficiency. The evaluated EPS showed non-newtonian and pseudoplastic behavior, however they also presented differences as to the apparent viscosity at the same shear rate. At the shear rate of 1 s -1 all isolates were different, while at the shear rate of 40 s -1 the isolates 53.5 and 30.6a2 were the same, differing from the isolate 8.1c. Genetic similarity of the isolates was in agreement with the rheology results, where bacteria that synthesized EPS with lower apparent viscosity presented the higher similarity.

Phenotypic diversity and amylolytic activity of fast growing rhizobia from pigeonpea [Cajanus cajan (L.) Millsp.]

“…The main bacteria used industrially to the production of amylases belongs to Bacillus genus (25), but nodule forming bacteria has already demonstrated their potential for this purpose, being able to hydrolyze starch in culture medium supplemented with several starchy compounds (27). By the way, some strains evaluated, in the present study, present the capacity to produce some biopolymers industrially applied (EPS and PHB), using starch as sole carbon source (8,9). This result shows the potential to multiple biotechnological applications of rhizobia.…”

“…The metabolic characterization of Brazilian rhizobial strains has shown a great versatility of their potential to other biotechnological applications than inoculant production, such as production of microbial biopolymers (2,8,9), and enzymes with industrial application (19,20,21).…”

Cultivo De Bactérias Utilizando Glicerina Residual Para Obtenção De Exopolissacarídeos

“…Tempo ( De acordo com Figura 3, foi observado que as quatros soluções de EPSs produzidos pelos micro-organismos testado apresentaram comportamento não newtoniano, pseudoplástico. Um comportamento não newtoniano de fluido se caracteriza pela variação da viscosidade em função da taxa de cisalhamento e os fluidos pseudoplásticos são não newtoniano, em que o aumento da taxa de cisalhamento resulta em decréscimo da viscosidade (Fernandes et al, 2010). Essa característica reológica pseudoplástica tem sido observada por inúmeros autores no estudo de EPSs produzidos por Rhizobium sp (Kaci et al, 2005;Barreto, 2011;Aranda-Selverio et al, 2010;Fernandes et al, 2010) e em bactérias do gênero Xanthomonas (Rottava et al, 2009 …”

Phenotypic and molecular fingerprinting of fast growing rhizobia of field-grown pigeonpea from the eastern edge of the Brazilian Pantanal

“…The isolation and characterization of rhizobia from grain legumes such as soybean, cowpea, and common bean, have resulted in the identification of bacteria able to fix high amounts of N for use in improving crop nutrition and yield (Hungria et al, 2000;Martins et al, 2003). On the other hand, rhizobial isolation from other neglected crops, such as those used as green manure, is beginning in Brazil, and recent studies regarding the diversity and biotechnological applications of bacteria from green manure root nodules have shown great potential (Fernandes Jr. et al, 2010Lima et al, 2012).…”