| 초록 |
The fructose homopolymer, levan, is found in plants and especially in bioproducts of microorganisms. Plant levans, graminans and phleins, have shorter residues (varies from 10 to approximately 200 fructose residues) than microbial levans of which molecular weights are up to several million daltons with multiple branches. Microbial levans are produced extracellularly from sucrose- and raffinose-based substrates by levansucrase (sucrose 6-fructosyltransferase, EC 2.4.1.10) from a wide range of taxa such as bacteria, yeasts, and fungi (Han, 1990; Hendry and Wallace, 1993). The production and utilization of levan in the industrial field have been strictly limited, and only a few papers have reported the production of levan using fermentation techniques (Elisashvili, 1984; Becker et al., 1990; Han, 1990; Keith et al., 1991; Uchiyama, 1993; Ohtsuka et al., 1992). Recently, great interest in this fructan has been renewed to discover applications for levan as a new industrial gum in the fields of cosmetics, foods like dietary fiber and pharmaceutical goods. |
