Fungal Inulinases: Enzymology, Molecular Biology and Biotechnology

Abstract

Abstract: Inulin is a fructan in which linear chains of ,8-(2--+1)-linked n-fructofuranose molecules are attached to sucrose at the reducing end. Inulinases have been encountered in higher plants and in microorgan- isms, including filamentous fungi, yeasts and bacteria. Exoinulinases exo- and endoinulinases from filamentous fungi have been purified and characterized as monomeric glycoproteins. The inulinase genes from Aspergillus and Penicillium spp. have been cloned and the deduced amino acid sequences included conserved sequences in the ,8-fructofuranosidase superfamily. A phylogenetic analysis showed that fungal exo- and endoinulinases have independently evolved the respective hydrolytic activities toward terminal and internal ,8-(2--+1)- fructofuranosidic linkages in inulin. Aspergillus niger inulinases in an immobilized form were applied to the continuous production of fructose syrup or inulo-oligosaccharides from inulin. High concentrations of ethanol were produced from pure inulin or Jerusalem artichoke tubers by a simultaneous saccharification and fermentation process using A. niger and Saccharomyces cerevisiae.