title: From inulin to fructose syrups using sol-gel immobilized inulinase.
abstract: The present work aims to provide the basic characterization of sol-gel immobilized inulinase, a biocatalyst configuration yet unexploited, using as model system the hydrolysis of inulin to fructose. Porous xerogel particles with dimensions in slight excess of 10 μm were obtained, yielding an immobilization efficiency of roughly 80%. The temperature- and pH-activity profiles displayed a broader bell-shaped pattern as a result of immobilization. In the latter case, a shift of the optimal pH of 0.5 pH units was observed towards a less acidic environment. The kinetic parameters estimated from the typical Michaelis-Menten kinetics suggest that immobilization in sol-gel did not tamper with the native enzyme conformation, but on the other hand, entrapment brought along mass transfer limitations. The sol-gel biocatalyst displayed a promising operational stability, since it was used in more than 20 consecutive 24-hour batch runs without noticeable decay in product yield. The performance of sol-gel biocatalyst particles doped with magnetite roughly matched the performance of simple sol-gel particles in a single batch run. However, the operational stability of the former proved poorer, since activity decay was evident after four consecutive 24-hour batch runs.
authors: IBB-Institute for Biotechnology and Bioengineering, Centre for Biological and Chemical Engineering, Instituto Superior Técnico, 1049-001, Lisbon, Portugal.
authors: Gonçalo L M
authors: GL
authors: Santa
authors: Susana M S A
authors: SM
authors: Bernardino
authors: Salomé
authors: S
authors: Magalhães
authors: Vanessa
authors: V
authors: Mendes
authors: Marco P C
authors: MP
authors: Marques
authors: Luís P
authors: LP
authors: Fonseca
authors: Pedro
authors: P
authors: Fernandes
mesh_terms: D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry* / Q000378:metabolism*; D005632:Fructose / Q000378:metabolism*; D005782:Gels / Q000737:chemistry*; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007444:Inulin / Q000378:metabolism*; D007700:Kinetics
chemical_list: D004800:Enzymes, Immobilized; D005782:Gels; D005632:Fructose; D007444:Inulin; D006026:Glycoside Hydrolases; C023086:inulinase