Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4036 | Biochemical Engineering Journal | 2010 | 7 Pages |
Erwinia sp. D12 is able to produce an isomaltulose synthase (EC 5.4.99.11) that converts sucrose into isomaltulose. The enzyme was partially purified using a two-step chromatographic process on DEAE-Sephadex A-50 and DEAE-Sepharose CL-6B. The molecular mass of 63 kDa was estimated by Sephadex G-200 gel filtration, and the Km and Vmax values determined for the enzyme were 138 mM and 9.81 μmol/min/mg protein with sucrose as the substrate, respectively. Enzyme activity was optimal at pH 6.0 and 40 °C. The glucosyltransferase was completely inhibited by Hg2+ and Ag+. An experimental design and response surface methodology were used to evaluate the influences of temperature, pH and substrate concentration on isomaltulose production from cells immobilized in chitosan. With the aid of a two-level full factorial design (23-FFD), the statistical analysis of the results showed that, in the range studied, the factors had a significant (p < 0.05) effect on isomaltulose production. The conditions that improved isomaltulose production were: temperature around 35 °C, pH 6.0 and sucrose concentration lower than 40%.