Entrapment of glutaraldehyde-crosslinked cells from Aspergillus oryzae IPT-301 in calcium alginate for high transfructosylation activity

Abstract

BACKGROUND: Fructooligosaccharides (FOS) are sweeteners produced through the use of enzymes called fructosyltransferases (FTases) (EC 2.4.1.9). However, FTase's reuse is meager and the cost of the enzyme production is high, which turns the FOS production economically unfeasible. In order to lessen these issues, the study aims the immobilization of cells from Aspergillus oryzae IPT301, containing FTase enzyme previously glutaraldehydecrosslinked, by means of entrapment in calcium alginate beads. The conditions to obtain the particles, such as alginate type, mycelium mechanical dispersion, degree of crosslinking, size of the beads, and their reflections on transfructosylation activity (AT) were previously evaluated.

RESULTS: The highest AT used low viscosity alginate solution (4.0% w/w) crosslinked with calcium chloride (0.2 molL1) and beads mean diameter of 2.15mm. The entrapment conditions were complemented by conducting the reaction under different temperatures, pH values, substrate concentrations and by reusing the beads. The highest transfructosylation activities were obtained under reaction conditions of 50 °C, pH 5.5, and substrate concentration of 400 gL1.

CONCLUSION: The AT levels found with the glutaraldehydecrosslinked and entrapped cells in calcium alginate were about 70% higher than the ones obtained with free cells, not glutaraldehydecrosslinked. Moreover, the immobilized cells (crosslinked+entrapped) retained their AT up to the third cycle of total sucrose depletion in the reaction medium, attesting the potential use of the beads in continuous FOS production.