Characterization of a glucosyltransferase from Erwinia sp D12 and the conversion of sucrose into isomaltulose by immobilized cells

Abstract

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 oil 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 K(m) and V(max) values determined for the enzyme were 138 mM and 9.81 mu mol/min/mg protein with Sucrose as the substrate, respectively. Enzyme activity was optimal at pH 6.0 and 40 degrees C. The glucosyltransferase was completely inhibited by Hg(2+) and Ag(+). An experimental design and response Surface methodology were used to evaluate the influences of temperature, pH and substrate concentration oil isomaltulose production from cells immobilized in chitosan. With the aid of a two-level full factorial design (2(3)-FFD), the statistical analysis of the results showed that, in the range Studied. the factors had a significant (p<0.05) effect oil isomaltulose production. The conditions that improved isomaltulose production were: temperature around 35 degrees C, pH 6.0 and Sucrose concentration lower than 40%. (C) 2009 Elsevier B.V. All rights reserved.