Immobilization of Cell-Associated Enzyme by Entrapping in Gluten Matrix

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Abstract
Gluten is advantageous for use as a new base material for cell and enzyme immobilization because it is biodegradable, cheaper than other natural polymers and readily available. In this work, a procedure for immobilization of cell-associated enzymes by entrapping within gluten matrices was developed. According to this method, cells of E. coli containing penicillin G acylase were mixed with gluten solution during the formation of gel, and the resultant gel was hardened by the addition of oxidized starch or glutaraldehyde. Scanning electron micrographs of the cell-immobilized preparations indicated that they were porous and the pore size decreased with increasing the dosage of cross-linking agent. Oxidized starch was superior to glutaraldehyde as the crosslinker, since the gel matrices hardened by the former were more accessible to the substrate and less harmful to the enzyme. The immobilized preparations in the form of either a single sheet or small pieces containing a biomass concentration up to 10%, w/w were effective for catalyzing the hydrolysis of penicillin G. Neither the optimal temperature nor optimal pH for the activity of cell-associated enzymes was changed by immobilization. In order to establish a membrane reactor for large-scale production, a stainless steel net could be used as the support for formulating a cell-immobilized gluten sheet.