Purification of inulin fructotransferase (DFA I-producing) from Arthrobacter sp. MCI2493 and production of DFA I from inulin by the enzyme

An extracellular enzyme that produces di-D-fructofuranose-2',1;2,1' dianhydride from inulin was purified from the culture broth of Arthrobacter sp. MC12493. The molecular weight of the enzyme was 40,000 by gel filtration and SDS polyacrylamide gel electrophoresis. The enzyme had maximum activity at pH 6.0 and 50 degrees C. Using this purified enzyme, 100 g/liter inulin was converted into 60 g/liter of DFA I, nystose, and 1-F-fructofuranosyl-nystose after incubation for 30 h.