Produção e caracterização do biopolimero produzido por Beijerinckia sp isolada do solo cultivado com cana-de-açucar da região de Ribeiro Preto-São Paulo-Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

1995

RESUMO

Two microorganisms were isolated and selecionated from a sugar cane plantation from the North-East region of the São Paulo. They were identified as Beijerinckia sp, strains 7070 and 9102AA . Sucrose solutions at concentrations from 0.1 to 5.0% in Yeast Malt medium were used to determine cellular growth of the 7070 strain. The 1 % sucrose medium showed the best result. The culture kinetic behavior of this strain was determinated in a 1 % sucrose medium, the optimal growth was obtained, at 27°C and 100 r.p.m. for 54 h. The logarithmical phase was completed at 18 h. The 7070 and 9102AA strains produced extracellular biopolymers in the following medium (g/l): K2HP04, 2.0; MgS04.7H20, 2.7; KH2P04 13.62; yeast extract, 0.2; tryptose, 2.0 and glucose or sucrose 20 or 50; pH 6.5. The fermentation conditions were 96 h, 200 r.p.m. at 15, 20, 24, 27 and 30°C. The larger yield of biopolymer was obtained from the medium containing 50 g/l sucrose, at 20°C, 200 r.p.m. during 96h. Under these conditions 17.02 g/l of biopolymer were obtained. Study of the composition of the B-27 biopolymer produced by the 7070 strain (5% sucrose, 27°C, 200 r.p.m., 96 h) revealed the presence of glucose, galactose, manose, galacturonic and glucuronic acids. B-27 aqueous solutions at 1, 3 and 6% concentration, had their apparent viscosity measured at 25°C and shear rate 0.3 S-I. The results were 160, 5.700 and 78.000 cP, respectively. Viscoelasticity analyses at OOC to 3% B-27 aqueous solution plus 0.6% guar gum and of 6% B-27 aqueous solution plus 50 mM CaC12, showed that both can form a gel. The CaC12 (0.5% and 1.0%) added to a 1 % B-27 aqueous solution increased the solution s viscosity at pH 3 and did not affect the viscosity at pH 7. The 7070 strain biopolymer showed good stability in a wide range, of 2.5 to 12.5 pH and under heating up to 100°C. Tests performed after one year showed that the biopolymer solutions are stable during that time.

ASSUNTO(S)

biopolimero cana-de-açucar - melhoramento genetico cana-de-açucar - ribeirão preto (sp)

ACESSO AO ARTIGO

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