engleski

Glucose biotransformation in a microreactor

Glucose oxidase (beta-D-glucose: oxygen-1- oxidoreductase, EC 1.1.3.4) is a dimeric glycoprotein consisting of two identical polypeptide chains that are covalently linked together via disulfide bonds. It is a naturally produced enzyme by some fungi and insects (e.g. Pleurotus ostreatus, Aspergillus niger, Penicillium pinophilum, honey bee (Apis mellifera L.)). This enzyme catalyses the oxidation of beta- D-glucose to D-glucono-delta-lactone and H2O2 using molecular oxygen as an electron acceptor. This reaction can be divided in to a reductive and an oxidative step. In the reductive reaction, glucose oxidase catalyzes the oxidation of beta-D- glucose to D-glucono-delta-lactone, which is non- enzymatically hydrolyzed to gluconic acid. Glucose oxidase is commercially used for the production of gluconic acid and as a preservative in the food industry. In this work application of glucose oxidase for biotransformation in a microreactor is studied. Prior to biotransformation experiments flow profile analysis for two phase aqueous system was performed. Glucose oxidase catalyzed glucose biotransformations were carried out in three different continuously operated tubular microreactors ; (i) microreactor with internal volume of 6 µL with two inflows (“Y” shaped) and one outflow (specific surface roughness of 1 µm), (ii) microreactor with internal volume of 6 µL with two inflows and two outflows (“Y” shaped) without surface roughness, and (iii) microreactor equipped with micromixers with internal volume of 2 µL with two inflows (“Y” shaped) and one outflow (specific surface roughness of 1 µm). The effects of two different inlet oxygen concentrations (ci, oxygen = 0.186 mmol dm-3, 0.271 mmol dm-3) on glucose conversion were investigated. The maximum conversion of X = 35.26 % was achieved at the higher oxygen concentration of ci, oxygen = 0.271 mmol dm-3 for residence time of 2.4 s in the 2 µL microreactor equipped with microcromixers.

glucose oxidase; biotransformation; microreactor

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