The glucosyltransferase of Erwinia sp D12 is able to convert sucrose into isomaltulose (6-0-alpha-D-glucopyranosyl-D-fructofuranose), an alternative sugar which presents low cariogenic potential, and can be used to produce chocolate, chewing gum and candy. The isomaltulose is also used to produce isomalt, a mixture of alcohol-sugar with a low caloric value and low cariogenicity power. In the study of the influence of the components of the culture medium in the glucosyltransferase production in flasks under shaking conditions, the highest activity (12.8 units of activity /mL of culture medium) was obtained in culture medium A, containing molasses 12% (p/v) of the total soluble solid, peptone 4% (p/v) and meat extract 0,4% (p/v). In the study of the effects of time and temperature on the fermentation of Erwinia sp D12 in a 3L New Brunswick fermentor containing culture medium A. the highest glucosyltransferase activity (15.6 units of activity /mL of culture medium) was obtained during the exponential growth phase after 8 hours of fermentation at 30ºC. In the production of isomaltulose from enzymatic transformation of sucrose by Erwinia sp D12 cells immobilized in calcium alginate, the effects of the temperature (25-35ºC) and substrate concentration (12,5-60%) were evaluated, the yield of isomaltulose was approximately 50%, from sucrose solutions ranging from 20 to 30% at 35ºC. Excess of sucrose affected the activity of the immobilized cell, decreasing conversion of sucrose into isomaltulose. The syrup obtained was purified through Ion Exchange Chromatography, and the crystallization of eluent by the decreasing temperature. The obtained crystals presented 91,39% of isomaltulose.
isomaltulose; glucosyltransferase; Erwinia sp; Cells Immobilization
