Preparation and characterization of cross-linked enzyme aggregates of dextransucrase from Leuconostoc mesenteroides B-512F

Abstract

Abstract We describe the development of cross-linked enzyme aggregates (CLEA) of dextransucrase of Leuconostoc mesenteroides B-512 F. Treatments of enzyme preparation using dextranase were evaluated varying incubation time to remove the dextran layer involving the enzyme molecule, turning it suitable for immobilization. Results showed 21 days of treatment as the best outcome. Subsequently, we tested different water-miscible organic solvents as precipitants, the reaction and centrifugation times, and the concentration of cross-linker agent (glutaraldehyde) in the preparation of CLEA. Optimal conditions were: the use of isopropanol as solvent, 30 min of centrifugation time, 3 h of cross-linking time, and 100 mM of glutaraldehyde. A central composite design was carried out to optimize conditions to obtain the highest enzymatic activity, testing the pH (3.0–7.0) and temperature (20 °C-60 °C). Results showed that dextransucrase CLEA operate at optimal pH of 3.0 and temperature of 60 °C. The operational stability of the immobilized biocatalyst showed up to 30% of residual activity after 10 cycles of reuse, in a solution of 100 mM of sucrose and 600 mM of maltose. The preparation of dextransucrase CLEA is described for the first time and results suggest that this novel immobilized biocatalyst has potential in many industrial applications.