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Fructans—fructose-based oligo- or polysaccharides—are de novo synthesized from sucrose by transfructosylating enzymes of microorganisms and plants. Fructan-producing enzymes belong to glycoside hydrolase families 32 and 68. Levansucrases, inulosucrases, some invertases, sucrose:sucrose 1-fructosyl transferases, fructan:fructan 1-fructosyl transferases, sucrose:fructan 6-fructosyl transferases and β-fructofuranosidases synthesize independently or in cascades a wide variety of fructose-containing saccharides. Fructans from different sources often differ in the linkage between the monosaccharide residues and the degree of polymerization. This chapter reviews the literature on fructan-metabolizing enzymes from bacteria, haloarchaea, yeasts, filamentous fungi, mono- and dicot plants. The focus is mostly on the product spectra of the enzymes, structure-function relationships that determine substrate …