Imobilização da enzima frutosiltransferase extracelular de Rhodotorula sp. e aplicação na produção de frutooligossacarideos. / Imobilization of extracellular enzyme fructosyltransferase from Rhodotorula sp. and application in fructooligosaccharides production.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Fructooligosaccharides (FOS) production by immobilized enzymes encloses two concepts that have faced great expansion in the last few years: industrial application of enzymes and functional foods. The option for enzyme immobilization is mainly induced by the easiness of controlling the reaction and the possibility of reusing the biocatalyst, besides the fact of allowing industrial scale-up. Amongst functional foods, there are the FOS for acting as a prebiotic inducing the growth of a desirable and beneficial microflora to our organism. Yeasts from the genre Rhodotorula has demonstrated a great transfructosilation potential and its extracellular enzyme recovered from fermented medium by alcohol precipitation were immobilized on different supports and by different methodologies in order to select the most adequate of them. The best results were achieved immobilizing the enzyme by adsorption on a solid acid support consisted of niobium ore and graphite, commercialized for Companhia Brasileira de Metalurgia e Mineração. The immobilization efficiency reached 97,76% at a rate of 164 Ui/g of support. Considering the immobilized enzyme, the pH profile changed to more basics values comparing to free enzyme, indicating an effect caused by negative charge of the support. Salt addition at 10 mM to incubation medium demonstrated to increase thermal stability, especially for CuSO4 salt. At pH 4,5 and 6,0 high activity and good stability were observed in different temperatures, and both were selected for system characterization. The half-life obtained at 50oC and pH 4,5 and 6,0 were respectively 24 and 48 days and the maximum activities for each pH were at temperature of 61oC and 63oC. Enzymatic kinetic for the immobilized enzyme presented inhibition by substrate concentration, effect not observed with free enzyme. FOS synthesis with sucrose at 50% as starting substrate were conducted in micro-reactors in both pH and the FOS conversion obtained were around 60%, similar to free enzyme. Based in these results it is possible to say that this methodology for enzyme immobilization is viable for application in large scale bioreactors for FOS production.

ASSUNTO(S)

alginatos adsorption transfrutosilação adsorção zirconium niobio niobium zirconio alginates trasnfructosylation

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