Production of inulin fructotransferase (depolymerizing) by Arthrobacter sp. H65-7 and preparation of DFA III from inulin by the enzyme

Abstract

A bacterial strain H65-7 isolated from soil as an inulin-assimilating microorganism produces inulin fructotransferase (inulase II) which converts inulin into di- d-fructofuranose-1,2′:2,3′-dianhydride (DFA III). This strain was classified as Arthrobacter sp. The inulase II production was induced by inulin, and markedly enhanced by the addition of yeast extract. Under optimal conditions, the enzyme activity in the culture supernatant reached 90 units/ml after cultivation for 18 h. The optimum pH and temperature for the enzyme reaction were 5.5 and 60°C, respectively. The enzyme was stable within a pH range of 4.5 to 9.0 and at up to 75°C. Using this crude enzyme, 300 mg/ml of inulin was converted into 237 mg/ml of DFA III after incubation for 4 h.