Recovery and properties of a fructooligosaccharides-producing beta-fructofuranosidase from Aspergillus japonicus CCRC 38011.

The fungus (Aspergillus japonicus CCRC 38011) was found to be able to produce beta-fructofuranosidase with high transfructosylating activity (Ut), a key enzyme involved in synthesis of fructooligosaccharides from sucrose. The Ut productivities of this microorganism were 191.5 units/ml broth in a 6-L jar-fermentor and 256.1 units/ml broth in a 1000-L pilot-fermentor in a modified medium containing 8% sucrose as a carbon source. Most of the Ut of this microorganism was found to be bound with mycelia. Incubation and sonication treatment extracted this enzyme from mycelia with maximum efficiencies of 66.3% and 44.3%, respectively. On the other hand, homogenization and freeze-thawing treatment had only a small effect on enzyme extraction. The soluble enzyme extracted from mycelia by incubation at pH 5.0 and 40 degrees C for 3 hours could be easily recovered and purified by acetone precipitation. The recovery of Ut from the crude enzyme solution was 99.5% by mixing the solution with an equal volume of acetone at 4 degrees C, followed by centrifugation. The purification factor of acetone precipitation was 15.8. The optimum pH and temperature of Ut was 5.0 and 65-70 degrees C, respectively. The enzyme was stable at a pH between 4.0 and 5.0 and at a temperature below 60 degrees C.