Abstract: Inulin is a soluble dietary fiber that has been reported to show good physicochemical properties and significant physiological functions, enabling it to be applied widely in foods. Inulosucrase (ISase) can use sucrose as the sole substrate to synthesize high-molecular-mass microbial inulin in one step. Currently, 15 microbial ISases have been identified, and the crystal structure of one of them has been solved. There are few studies on Isase in China. This review comprehensively analyzes the crystal structure and catalytic mechanism of ISase. Special emphasis is put on discussing the modulation of inulin chain length and the applications of ISase in the production of inulin, oligosaccharides, novel oligosaccharides and inulin nanoparticles. Based on previous studies of ISase, future development trends are discussed.

Key words: inulosucrase; microbial inulin; crystal structure; catalytic mechanism; application