Production in Nicotiana benthamiana of a thermotolerant glucose oxidase that shows enzybiotic activity against Escherichia coli and Staphylococcus aureus

Abstract

Glucose oxidase (GOX) catalyzes the FAD-dependent oxidation of α-D-glucose to D-gluconolactone with production of hydrogen peroxide. This enzyme encounters many biotechnological applications from glucose sensors to applications in food, pharma and textile industries. For this purpose, recombinant GOX versions, usually derived from Aspergillus niger, are produced in fermentation systems, frequently in filamentous fungi because other production platforms such as bacteria or yeast have rendered meager results. We wondered whether A. niger GOX, more specifically a mutant version with superior thermotolerant properties, could be efficiently produced in Nicotiana benthamiana plants. To this aim, we used a tobacco mosaic virus-derived vector that is inoculated into plant tissues using Agrobacterium tumefaciens. Results exhibited the efficient production of the recombinant GOX in plants and the facile downstream purification when the recombinant protein is targeted to the apoplast, the space between plasma membranes and cell walls. The plant-made recombinant GOX displayed excellent catalytic properties in broad pH and temperature conditions. In addition to establishing a new strategy to produce recombinant GOX in plants as a green alternative to traditional fungal fermentation, we further investigated the potential application of this protein as an ezybiotic. Results exhibited a remarkable bacteriocide activity against Escherichia coli and Staphylococcus aureus.