Aspergillus niger mutant 817 was grown in submerged culture with sucrose. Inulinase was partially purified from the culture filtrate by DEAE-Cellulofine A-500 chromatography. The complex enzyme preparation containing both exo- and endoinulinases was immobilized covalently onto a porous cellulose derivative, Amino-Cellulofine, by the carbodiimide method at pH 5.0. The immobilized enzyme had 160 U inulinase activity/g (wet wt.) of the support, with the immobilization yield of 96% on a protein basis and the activity yield of 15%. The maximum inulinase activity occurred at pH 5.2 and 50 degrees C. The immobilized enzyme was stable in the pH ranges of 4.5 to 6.5 at 30 degrees C and 5.0 to 6.0 at 50 degrees C. Enzyme stability was retained up to 60 degrees C. In a packed-bed column reactor containing 8 ml of the immobilized inulinase, a 5.0% (w/v) solution (pH 5.0) of pure dahlia inulin was completely hydrolyzed at a flow rate of 1.0 ml/min at 40 degrees C over a 45-d period of continuous operation. The volumetric productivity in the reactor was 410 g reducing sugars/l/h. The reaction product was a mixture of 97% D-fructose and 3% D-glucose.