DFA I (difructose dianhydride I) is a disaccharide composed of 2 molecules of fructose. DFA I is generated from inulin by the action of an enzyme produced by a bacterium Arthrobacter globiformis S14-3. The gene encoding the enzyme was cloned and the nucleotides sequenced, for the first time. The sequence indicated that the native enzyme is composed of 392 amino acid residues. The 1.5 kb DNA fragment encoding the gene was found to produce the active enzyme, under the control of the lac promoter of pUC 119.