18 production of glicosiltransferase of klebsiella sp and otimização of the process of conversion of sacarose in isomaltulose. / Produção de glicosiltransferase de Klebsiella sp 18 e otimização do processo de conversão de sacarose em isomaltulose.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The strain Klebsiella sp 18 produces glucosyltransferase, an enzyme that converts sucrose in isomaltulose. This sugar is not cariogenic and it is naturally found in small amounts in honey and sugar cane. Isomaltulose has been used as an alternative sugar in food production. The optimization of culture medium for the production of glucosyltransferase by Klebsiella sp 18, in shake flasks, was realized using experimental design methodology and surface response analysis. The medium components studied were sugar cane molasses, bacteriological peptone and yeast extract Prodex Lac SDÒ. The highest glucosyltransferase production was reached in culture medium composed of 80 g/L of sugar cane molasses, 7 g/L of bacteriological peptone and 20 g/L of yeast extract Prodex Lac SDÒ. The cultivation of Klebsiella sp 18 using the optimized medium showed an enzyme activity of 9,94 AU/mL, after 24 hours, at 30°C. The relationship between fermentation time, change of medium pH, growth of microorganism and glucosyltransferase production was studied using 5 liters fermentation vessel, with optimized culture medium, at different temperatures from 26°C to 35°C. The highest enzyme activity, 21,78 AU/mL, was reached after 8 hours, at 28°C. The immobilization of Klebsiella sp 18 cells in calcium alginate and the conversion from sucrose to isomaltulose was studied. The effects of cell and calcium alginate concentrations on cell immobilization were also verified. The best conversion rate of sucrose to isomaltulose was 62,1% after 24 hours, using 20% of cellular suspension and 2% of calcium alginate solution.

ASSUNTO(S)

otimização glicosiltransfera sacarose immobilization

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