Immobilization of Aspergillus oryzae IPT-301 Cells with High Transfructosylation Activity on Polyurethane Sponge for Fructooligosaccharide Production in Batch Mode

A stable and active biocatalyst for fructooligosaccharide (FOS) production was synthesized by immobilizing A. oryzae IPT-301 cells on a polyurethane sponge (PS) during submerged cultivation. Comparisons between immobilized and cross-linked immobilized cells revealed similar biochemical properties. The highest cell concentration immobilized in PS (11.89 ± 2.29 g cells g support^-1) was obtained after 32 h. Both biocatalysts performed optimally at 50 °C, pH 5.5, and 480.2 g L^-1 sucrose, showing a V _max of 3500 μmol g^-1 min^-1 and high selectivity for 1-kestose (28.23%). They exhibited a half-life of 300 min at 50 °C, retained 40% activity after 28 days of storage and 50% activity after 12 reaction cycles. FOS productivity reached 116 g L^-1 h^-1 with a 24% yield. Statistical analysis confirmed that cross-linking did not significantly influence performance. The results show that in situ immobilization on PS is a simple, efficient strategy for producing stable biocatalysts for FOS synthesis.