Coated-Wall Mini Reactor for Inulin Hydrolysis

Abstract

Miniaturized reactors and enzyme immobilization are tools that can contribute significantly for the implementation of efficient and cost effective bioprocesses. The present work fits within such scope, and focuses on the development of a continuous flow, low-cost mini reactor, aimed to provide a suitable platform for enzymatic bioconversion systems. In this particular case, inulin hydrolysis to fructose promoted by inulinase, was used as model system. Thus, the inner walls of a silicone tube were coated with amino groups and inulinase was subsequently immobilized through glutaraldehyde cross-linking. As an outcome of immobilization, the optimal temperature increased by 10ºC, and allowed operation up to 80ºC, at which temperature the free enzyme is totally inactive. Moreover, the activity of immobilized enzyme was enhanced at pH 4, as compared to the free form. Enzyme-substrate affinity was not affected by immobilization. A product yield of 80% was obtained during 5 days of continuous operation. Keywords: Coated-wall reactor, continuous flow operation, covalent binding, fructose syrup, enzyme immobilization, inulin hydrolysis, inulinase, mini reactors, miniaturization, silicone tubing